WO2025249451A1 - Multi-step type needleless syringe or needleless injection system, and driving method and control program thereof - Google Patents

Abstract

[PROBLEM] An objective of the present invention is to develop a multi-step type needleless syringe in which an injection liquid in a single ampule can be repeatedly injected over multiple steps. [SOLUTION] The present invention provides a needleless syringe or a needleless injection system in which an elastic body energy storage unit for storing energy in an elastic body for pressing a piston and a piston head stop position adjustment unit for adjusting the stop position of a piston head are each driven by actuators, and the actuators thereof can be controlled by a control unit to repeatedly A) store energy in the elastic body by means of the elastic body storage unit, B) change the stop position of the piston head in the forward direction by means of the piston head stop position adjustment unit, and C) drive the piston in the forward direction by releasing the energy in the elastic body, and thereby gradually press using the piston head and advance a plunger for pushing out an injection liquid in the ampule, and repeatedly inject the injection liquid in a single ampule over multiple steps.

Description

Multi-step needle-free syringe or needle-free injection system, and their driving method and control program

The present invention relates to a needle-free syringe or needle-free injection system that uses the force of an elastic body such as a spring to eject an injection solution at high speed, allowing the injection solution to be injected subcutaneously or into the skin without the use of a needle. It provides a multi-step needle-free syringe or needle-free injection system that can repeatedly eject the injection solution from a single ampule in multiple doses. The present invention also provides a drive method and control program for a needle-free syringe or needle-free injection system that can repeatedly eject the injection solution from a single ampule in multiple doses.

A needleless syringe is a medical device that can inject an injection solution into the subcutaneous or intracutaneous cavity without using a needle by ejecting the injection solution at high speed from a nozzle with a minute diameter.
Needle-free syringes have the advantage of being less painful than syringes that use needles because they do not pierce the skin with a needle, and also of being able to prevent infections such as viruses and injuries caused by needlestick injuries.

These advantages of needle-free syringes are particularly beneficial in medical care for children who fear needle injections and patients with acrophobia (apophobia). Following the needle-free syringe developed by the applicant becoming the first in Japan to receive approval for the manufacture and sale of medical devices, sales of the needle-free syringe Injex50 began in 2020, and at the time of filing this application, its use is particularly expanding in pediatric dentistry.

The most common driving principle for needle-free syringes is the elastic force of a spring, although other methods include gas pressure, electromagnetic force, and gunpowder. However, gas pressure and electromagnetic force methods have difficulty ejecting the injection liquid at high speed. Therefore, while small amounts of injection liquid can be injected into the skin (epidermis and dermis), they are unable to be injected subcutaneously (tissues deeper than the dermis). Gunpowder methods also have problems with adjusting the explosive force and safety. On the other hand, methods that use the elastic force of a spring or other elastic material apply stress to an elastic body such as a spring to deform it and accumulate elastic energy (storing the elastic body), and then release the deformed elastic body to suddenly release the accumulated elastic energy (discharging the elastic body). This allows the injection liquid to be ejected at high speed, and the elastic energy used for ejection is constant. Due to these characteristics, methods that use the elastic force of a spring or other elastic material can reliably and safely inject even small amounts of injection liquid subcutaneously, making them ideal for needle-free syringes.

The driving principle of a conventional needle-free syringe that utilizes the elastic force of a spring or the like is explained below using the diagrams shown in Patent Document 1, which was previously filed by one of the inventors of the present application.
FIG. 8 is a diagram in which new reference numerals have been added to FIGS. 23 and 24 of Patent Document 1 in accordance with the reference numerals used in this application.
FIG. 8(A) shows a state in which a spring in a conventional needleless syringe is compressed and charged, and FIG. 8(B) shows a state in which the compressed spring is released and the injection liquid is ejected.
As shown in FIG. 8(A), an ampoule 3A can be attached to the front of the needle-free syringe 1A. The ampoule 3A has a cylinder-like structure and contains an injection solution therein. By pushing a plunger 304A into the cylinder-like structure, the injection solution inside can be ejected. A piston 5A that can slide back and forth is housed inside the body of the needle-free syringe 1A, and a piston head 522A is provided at the front end of the piston 5A. Furthermore, a spring 6A that applies a forward force to the piston 5A is installed inside the needle-free syringe 1A. By manually moving the piston 5A backward, the spring 6A is compressed, as shown in FIG. 8(A). Here, a trigger finger 1211A prevents the piston 5A from moving forward, and the spring 6A remains in a compressed, "energized" state. Trigger finger 1211A is provided at the front end of trigger 1210A, and push end 1212A provided at the rear end of trigger 1210A is raised by the force of another spring, which pushes down trigger finger 1211A using the principle of leverage, preventing piston 5A from moving forward. To maintain the raised state of push end 1212A, safety lock 1220A, which can move back and forth, is pressed under push end 1212A to lock it.
8(B), the safety lock 1220A is moved backward to release the lock, and the push end 1212A is pushed downward to lift the trigger finger 1211A using the principle of leverage, allowing the force of the spring 6A to freely drive the piston 5A forward. By releasing the spring 6A in this way and driving the piston 5A forward at high speed, the piston head 522A presses the plunger 304A, and the injection liquid in the ampoule 3A can be injected at high speed from the minute-diameter discharge port 303A.

In the fields of skin disease treatment and cosmetic and hair growth medicine, medicinal liquids are sometimes injected into multiple locations on the skin. However, if a multi-step needle-free injector that dispenses the injection liquid from a single ampoule in multiple doses were developed, more efficient treatment would become possible in these medical fields as well.

Needle-free syringes that utilize the elastic force of a spring or other such material inject liquid by storing and releasing energy in an elastic body such as a spring. Therefore, it has been conventionally understood by those skilled in the art that continuous injections within a predetermined time are not possible, and that the amount of injection per injection cannot be set (paragraphs [0010] and [00011] of Patent Document 2). Therefore, the inventors of Patent Document 2 have succeeded in developing a needle-free injection system that utilizes gas pressure, making it possible to set the number of continuous injections, the time interval between continuous injections, the amount of injection per injection, etc. (paragraph [0001] of Patent Document 2).

However, as mentioned above, a system that utilizes the elastic force of a spring or the like is most suitable for a needle-free syringe, and therefore attempts have been made to develop a multi-step needle-free syringe that utilizes the elastic force of a spring or the like (Patent Documents 3 to 5).
Patent Document 3 discloses a needleless syringe that can inject a syringe in several divided doses by gradually releasing the energy of a charged spring in multiple steps, thereby pressing the plunger in multiple steps.
Patent Documents 4 and 5 disclose needleless syringes capable of multiple injections by transmitting the driving force of a piston by the force of a deenergized spring to a plunger via a cylindrical stepped barrel (revolver) having multiple spiral staircase-like steps. Specifically, the lowest step of the stepped barrel (revolver) is initially placed in contact with the plunger, and the pressure of the piston, driven by the charging and discharging of the spring, is transmitted to the plunger via the stepped barrel (revolver), causing the plunger to move forward and perform the first injection. Next, the stepped barrel (revolver) is rotated so that the next step, located further forward, is placed in contact with the plunger. Then, the pressure of the piston, driven by the charging and discharging of the spring, is transmitted to the plunger via the stepped barrel (revolver), causing the plunger to move further forward and perform the second injection. By repeating this operation, multiple injections are performed.

International Publication No. WO2014/042930 JP 2015-036108 A JP 2012-055641 A Special Publication No. 2022-527712 Japanese Patent Application Laid-Open No. 2020-179038

As mentioned above, among needle-free syringes that utilize the elastic force of a spring or the like, attempts have been made to develop a multi-step needle-free syringe that injects the injection liquid from a single ampule in multiple steps (Patent Documents 3 to 5). However, the needle-free syringe described in Patent Document 3 injects the injection liquid by gradually releasing the energized spring in multiple steps. Therefore, although the spring is sufficiently compressed and the elastic stress is large when it is first released, repeated stepwise releases of the energization spring stretch and the elastic stress decreases, resulting in a weakening of the injection force and an inability to obtain a constant injection force.
Furthermore, the needleless syringes described in Patent Documents 4 and 5 utilize a cylindrical stepped barrel (revolver) having multiple spiral staircase-like steps, and by rotating the stepped barrel (revolver) to change the position of the step that contacts the plunger, multiple injections are possible. However, because the amount of injection per injection is determined by the steps of the stepped barrel (revolver), the amount of injection per injection and the injection pressure are physically fixed, and there is a problem in that the injection amount and injection pressure of the injection liquid cannot be adjusted. Furthermore, the needleless syringes described in Patent Documents 4 and 5 require manual simultaneous compression of the spring and rotation of the stepped barrel (revolver), which forces the force of the spring to be weak, making it difficult to deliver the medicinal liquid subcutaneously.

The objective of this invention is to develop a multi-step needleless syringe with a new drive mechanism that can repeatedly inject the injection liquid from a single ampule in multiple doses, while maintaining a constant injection force even when injected repeatedly, allowing the injection volume and injection pressure to be adjusted, and further enabling automatic, continuous injection without manual operation.

In order to solve this problem, the inventors conducted extensive research and found that by using a piston connected to a piston base so that the relative forward and backward position of a piston rod equipped with a piston head with respect to the piston base can be changed, it is possible to arbitrarily adjust the stop position of the piston head that presses the plunger forward or backward. The inventors also found that by driving a piston head stop position adjustment unit that adjusts the stop position of the piston head and an elastic body energy storage unit that stores energy in the elastic body that presses the piston with actuators and controlling these actuators with a control unit, repeating the following: (a) energy storage of the elastic body by the elastic body energy storage unit, (b) forward position change of the piston head stop position adjustment unit with respect to the piston head, and (c) forward drive of the piston by deenergizing the elastic body, the plunger that pushes out the injection liquid in the ampule is advanced by the piston head in stages, and the injection liquid in a single ampule can be repeatedly injected in multiple divided doses. Furthermore, the inventors discovered that the elastic body can be charged each time an injection is made, resulting in a constant injection force, and that the injection volume and injection pressure can be adjusted by adjusting the distance at which the piston head stopping position is changed, and that automatic continuous injection is possible because an actuator is used instead of manual operation, leading to the completion of the present invention.
That is, the present invention provides the following invention [1] of a needle-free syringe or needle-free injection system.
[1] A needle-free syringe or needle-free injection system comprising: a machine case main body to the front of which an ampoule having a plunger for pushing out an injection liquid therein; a piston provided on the machine case main body so as to be slidable back and forth; and an elastic body for applying a forward force to the piston, wherein the piston head of the piston presses the plunger by releasing the stored energy of the elastic body to drive the piston forward, thereby injecting the injection liquid in the ampoule,
an elastic body energy storing unit that stores energy in the elastic body by moving the piston rearward;
a first actuator that drives the elastic energy storage portion;
a piston head stop position adjustment unit that adjusts a piston head stop position where the piston head stops when the stored energy of the elastic body is released to drive the piston forward;
a second actuator that drives the piston head stop position adjustment unit;
a control unit that controls the first actuator and the second actuator,
the piston has a piston base to which a forward force is applied by the elastic body, and a piston rod having the piston head,
the piston rod is connected to the piston base so that it can receive a forward force from the piston base and can change its front-to-rear position relative to the piston base,
the piston head stop position adjustment unit can adjust the piston head stop position by changing the relative position of the piston rod with respect to the piston base back and forth using the driving force of the second actuator,
a needle-free syringe or needle-free injection system, characterized in that the control unit controls the driving of the first actuator and the second actuator, and repeatedly charges the elastic body by the elastic body charging unit, changes the piston head stop position in the forward direction by the piston head stop position adjustment unit, and drives the piston in the forward direction by releasing the elastic body.

The needle-free syringe or needle-free injection system of the present invention has a piston head stop position adjustment unit that can adjust the stop position of the piston head, so that the number of injections per ampoule or the amount of injection liquid per injection can be changed or set by adjusting the distance by which the piston head stop position is moved forward.The inventors have discovered that by providing a needle-free syringe or needle-free injection system with an interface that sets the number of injections per ampoule or the amount of injection liquid per injection, and controlling the actuator that drives the piston head stop position adjustment unit in accordance with the user's settings via that interface, the user can change or set the number of injections per ampoule or the amount of injection liquid per injection.
That is, the present invention provides the following invention [2] of a needle-free syringe or needle-free injection system.
[2] The device further has an interface for setting the number of injections per ampoule or the amount of injection solution per injection,
The needle-free syringe or needle-free injection system described in [1] above, characterized in that the control unit controls the distance by which the piston head stop position is changed forward by controlling the drive amount of the second actuator according to the number of injections per ampoule or the amount of injection liquid per injection set by the user via the interface.

The needle-free syringe or needle-free injection system of the present invention is characterized by using a piston rod that is connected to the piston base so that it can receive a forward force from the piston base and can change its forward/backward position relative to the piston base. The connection structure between the piston rod and the piston base is not particularly limited and can take various structures, as will be described later, but a structure in which the piston rod is connected by a male and female thread is the simplest and can be easily manufactured.
That is, the present invention provides the following invention [3] of a needle-free syringe or needle-free injection system.
[3] The piston rod and the piston base are connected to each other by a male and female thread structure,
The needle-free syringe or needle-free injection system according to [1] or [2], wherein the piston head stop position adjustment unit changes the position of the piston rod relative to the piston base back and forth by rotating the piston rod and the piston base relatively with the driving force of the second actuator.

When the connecting structure of [3] above is adopted, it is necessary to rotate the piston rod and the piston base relatively by the driving force of the actuator. When rotating the piston rod, it is preferable that the structure of the piston rod and the piston head stop position adjustment part be as shown in the following [4].
That is, the present invention provides the following invention [4] of a needle-free syringe or needle-free injection system.
[4] A spur gear having a plurality of teeth extending linearly in the front-rear direction is formed on the outer periphery of a part of the piston rod,
The piston head stop position adjustment unit has a cylindrical internal gear that is slidable back and forth relative to the spur gear and has a plurality of teeth on its inner circumference that extend linearly in the back and forth direction,
The needle-free syringe or needle-free injection system described in [3] above, characterized in that the rotational driving force of the second actuator can be transmitted to the spur gear via the internal gear to rotate the piston rod, regardless of the position of the piston rod sliding back and forth.

As will be described later, the elastic body energy storage unit of the needle-free syringe or needle-free injection system of the present invention is not particularly limited and can take various mechanisms. However, a cam mechanism such as the following [5] is preferred because it can easily convert the rotational driving force of the actuator into driving force in the forward and backward directions of the piston.
That is, the present invention provides the following invention [5] of a needle-free syringe or needle-free injection system.
[5] The elastic energy storage unit has a cam that can convert the rotational motion of the first actuator into a forward-backward motion of the piston,
The needle-free syringe or needle-free injection system according to any one of [1] to [4] above, characterized in that the cam is provided rotatably around an axis in the front-rear direction along which the piston slides, and the cam has a shape in which the thickness in the front-rear direction of the part where it abuts against the piston changes with the rotation of the cam, thereby converting the rotational movement of the first actuator into movement in the front-rear direction of the piston and storing energy in the elastic body.

When the cam mechanism of the above [5] is adopted, it is preferable to further adopt the shape of the cam as shown in the following [6], since this allows the elastic body to be continuously energized and deenergized.
That is, the present invention provides the following invention [6] of a needle-free syringe or needle-free injection system.
[6] A portion in which the cam is shaped so that the thickness in the front-rear direction of the portion in contact with the piston gradually increases with the rotation of the cam, thereby enabling the elastic body to store energy;
The needle-free syringe or needle-free injection system according to [5] above, characterized in that it has a portion in which the thickness of the portion that comes into contact with the piston has a stepped shape that rapidly decreases as the cam rotates, thereby enabling the elastic body to be released.

The needle-free syringe or needle-free injection system of the present invention further includes a sensor that detects the front-rear position of the piston rod and a sensor that detects the front-rear position of the piston base, thereby making it possible to prevent excessive force from being applied to components such as the piston, elastic body, and ampoule, and to more accurately control the position of the piston head.
That is, the present invention provides the following invention [7] of a needle-free syringe or needle-free injection system.
[7] The needle-free syringe or needle-free injection system according to any one of [1] to [6] above, further comprising a piston rod position sensor capable of detecting the position of the piston rod in the forward/backward direction and transmitting the detection result to a control unit, or a piston base position sensor capable of detecting the position of the piston base in the forward/backward direction and transmitting the detection result to a control unit.

Although needleless syringes have difficulty penetrating loose skin when injecting an injection solution, they can easily penetrate the skin and inject subcutaneously when injecting an injection solution into taut skin. Therefore, it is preferable to attach an attachment to the front end of the needleless syringe, press the attachment against the skin to taut the skin, and then inject the injection solution into the skin. However, pressing the attachment against the skin causes pressure pain, which is particularly problematic when performing needleless injections into facial skin for cosmetic medical purposes. Even molding the attachment out of a flexible material did not solve this problem. Therefore, the inventors developed a vacuum attachment that can taut the skin by adsorbing the skin to the attachment using negative pressure generated by suction, without forcing the skin against the attachment.
That is, the present invention provides the following invention [8] of a needle-free syringe or needle-free injection system.
[8] A vacuum attachment having a cylindrical shape with two open ends, one of which can be attached to the plunger or the front of the machine body to which the plunger is attached, and the other of which can be brought into contact with the skin;
The needle-free syringe or needle-free injection system according to any one of [1] to [7] above, further comprising an aspirator that can bring the skin into close contact with the attachment by sucking air from within the vacuum attachment.

The present invention also provides the following inventions [9] and [10], which are methods for driving a needle-free syringe or a needle-free injection system.
[9] A method for driving a needle-free syringe or a needle-free injection system that has a machine case main body to the front of which an ampoule having a plunger for pushing out an injection liquid therein can be attached, a piston provided on the machine case main body so as to be slidable back and forth, and an elastic body that applies a forward force to the piston, and that can inject the injection liquid in the ampoule by pressing the plunger with a piston head of the piston by releasing the stored energy of the elastic body to drive the piston forward,
A) a step of energizing the elastic body using an elastic body energizing unit that energizes the elastic body by moving the piston rearward and a first actuator that drives the elastic body energizing unit;
B) changing the piston head stop position to a position in the forward direction by using a piston head stop position adjustment unit that adjusts a piston head stop position where the piston head stops when the stored energy in the elastic body is released to drive the piston forward, and a second actuator that drives the piston head stop position adjustment unit;
C) releasing the elastic body to drive the piston forward, causing the piston head of the piston to press the plunger, thereby injecting the injection liquid from the ampoule.

[10] The method for driving the needle-free syringe or needle-free injection system described in [9] above, characterized in that in step B), the distance by which the piston head stopping position is moved forward is controlled by controlling the drive amount of the second actuator in accordance with the number of injections of the injection liquid or the amount of injection liquid per injection set by the user.

In the method for driving the needle-free syringe or needle-free injection system of the present invention, if the steps of A) storing energy in the elastic body and B) changing the piston head stop position to a forward position are carried out simultaneously, the operating time for injecting the injection liquid can be shortened, which is a preferable driving method.
That is, the present invention provides the following invention [11], which is a method for driving a needle-free syringe or a needle-free injection system.
[11] The method for driving the needle-free syringe or needle-free injection system according to [9] or [10], characterized in that step A) and step B) are carried out simultaneously.

In the method for driving the needle-free syringe or needle-free injection system of the present invention, a sensor is used to detect the position of the piston rod, and when it is detected that the position of the piston rod has moved forward beyond a predetermined position, the driving of the second actuator is stopped, thereby preventing excessive force from being applied to parts such as the piston and the ampule, and making it possible to more accurately control the position of the piston head. Furthermore, when A) the step of storing energy in the elastic body and B) the step of changing the piston head stop position to a forward position are performed simultaneously, if the piston rod advances faster than the speed at which the piston base retreats, the piston head will press the plunger, causing leakage of the injection liquid. However, by stopping the actuator based on the sensor that detects the position of the piston rod, such leakage can be prevented.
That is, the present invention provides the following invention [11], which is a method for driving a needle-free syringe or a needle-free injection system.
[12] The method for driving a needle-free syringe or a needle-free injection system according to any one of [9] to [11] above, wherein in step B), a piston rod position sensor is used to detect the position of the piston rod in the forward/backward direction, and when it is detected that the position of the piston rod has moved forward beyond a predetermined position, driving of the second actuator is stopped.

In the method for driving the needle-free syringe or needle-free injection system of the present invention, if the steps of A) energizing the elastic body, B) changing the piston head stop position to a forward position, and C) deenergizing the elastic body to inject the injection liquid are carried out successively in a short period of time immediately before injecting the injection liquid, there is no need to maintain the energized state of the elastic body for a long period of time, and it is possible to prevent accidental injection of the injection liquid when the user does not intend, which is a preferable driving method.
That is, the present invention provides the following invention [13], which is a method for driving a needle-free syringe or a needle-free injection system.
[13] The method for driving the needle-free syringe or needle-free injection system according to any one of [9] to [12] above, characterized in that steps A) to C) are performed immediately before the injection of the injection liquid.

The present invention further provides a control program for a needle-free injector or needle-free injection system according to the following [14] to [17].
[14] A step of generating a command signal to drive the first actuator by a predetermined amount in order to energize the elastic body in the control unit of the needle-free syringe or needle-free injection system described in [1] above;
B') generating a command signal to drive the second actuator a predetermined amount to change the piston head stop position to a forward position;
C') generating a command signal to release the stored energy of the elastic body in order to release the energy of the elastic body.

[15] The control program described in [14], further comprising causing the control unit to execute information processing to determine the predetermined amount by which the second actuator is driven in step B') based on the number of injections of the injection liquid or the amount of injection liquid per injection set by the user.

[16] The control program described in [14] or [15], characterized in that it causes the control unit to simultaneously generate signals in step A') and step B').

[17] A control program according to any one of [14] to [16], characterized in that it causes the control unit to execute the information processing of A') to C') immediately after receiving a firing instruction signal from a user via an interface.

The needle-free syringe or needle-free injection system, and drive method and control program for the needle-free syringe or needle-free injection system of the present invention use an actuator to drive an elastic body energy storage unit that stores energy in the elastic body, and also use an actuator to drive a piston head stop position adjustment unit that adjusts the stop position of the piston head. The drive of these actuators is controlled by a control unit, and the elastic body energy storage unit repeatedly charges the elastic body, the piston head stop position adjustment unit changes the piston head stop position forward, and the piston is driven forward by releasing the elastic body. This has the effect of gradually pressing and advancing the plunger that pushes out the injection liquid in the ampule, making it possible to repeatedly inject the injection liquid in a single ampule in multiple doses.

1 is a schematic diagram showing the internal structure of a needle-free syringe according to a first embodiment of the present invention. FIG. 2A and 2B are cross-sectional views of the needle-free syringe of the first embodiment shown in Fig. 1. Fig. 2A shows a cross-sectional view taken along a plane including dashed line C1-C2 in Fig. 1, and Fig. 2B shows a cross-sectional view taken along a plane including dashed line C3-C4 in Fig. 1. 3A is a schematic diagram showing the state in which the cam and the piston follower are in contact with each other in the needle-free syringe of the first embodiment, and the change in the thickness of the cam. Fig. 3(A) is a schematic diagram showing the state in which the cam and the piston follower are in contact with each other, as viewed from the rear along the axis on which the piston in Fig. 1 slides. Fig. 3(B) is a graph showing the change in the thickness of the cam at the point where the cam and the piston follower are in contact with each other when the gearwheel rotates. 4A and 4B are schematic diagrams showing the operation of the internal structure of the needle-free syringe of the first embodiment when the piston head stop position is changed and the elastic body is released. Fig. 4(A) shows the state in which the piston head has moved forward from the state in Fig. 1. Fig. 4(B) shows the state in which the piston has stopped after being driven forward by releasing the elastic body (coil spring) from the state in Fig. 4(A). 5 is a flowchart showing information processing that an injection control program, which is part of the control program for the needle-free syringe of the first embodiment, causes an information processing device to execute. FIG. 2 is a schematic diagram showing a needle-free injection system according to a second embodiment of the present invention. Figure 7 is a schematic diagram showing the cross-sectional structure of the front end of a multi-step injector with a vacuum attachment attached, and how to use it. Figure 7(A) shows the state before the skin is attached to the vacuum attachment, and Figure 7(B) shows the state after the skin is attached to the vacuum attachment. 1 is a diagram illustrating the driving principle of a conventional needleless syringe that utilizes the elastic force of a spring or the like.

1. Needle-free syringe or needle-free injection system
1-1. Overview of the needle-free syringe or needle-free injection system The needle-free syringe or needle-free injection system of the present invention is a needle-free syringe that utilizes the elastic force of an elastic body such as a spring, and uses a piston that is slidable back and forth, and an elastic body that applies a forward force to the piston. By releasing the stored energy of the elastic body to drive the piston forward, the piston head presses the plunger of the ampule, and the injection liquid inside the ampule is injected at high speed.
In the present invention, an "elastic body" refers to a member that deforms when stress is applied and returns to its original shape when the stress is removed. The "elastic body" is not limited to, but examples of the elastic body that can be used include, but are not limited to, coil springs, leaf springs, compression springs, tension springs, rubber, etc.
In the present invention, "energy storage" refers to the accumulation of elastic energy in an elastic body by continuously applying stress to the elastic body to cause deformation, and "energy release" refers to the conversion of accumulated elastic energy into kinetic energy by releasing the stress and returning the deformed elastic body to its original shape.

The ampoule used in the needle-free syringe or needle-free injection system of the present invention can be attached to the front of the needle-free syringe housing. An ampoule typically has a cylinder that contains an injection solution, a minute-diameter nozzle at the front end of the cylinder, and a plunger that can be inserted into the cylinder and pushes out the injection solution inside. Since the injection solution to be injected into the body must be sterile, an ampoule is used by filling a sterilized injection solution into a sterilized ampoule, or an ampoule pre-filled with an injection solution is purchased and used. Once the injection solution has been completely injected, the used ampoule is usually disposable, and repeated injections can be performed by removing the ampoule attached to the front of the needle-free syringe housing and replacing it with a new ampoule.
In this way, the ampoule may be a separate component from the needle-free syringe of the present invention, and the needle-free syringe of the present invention may be sold with the ampoule removed.
Furthermore, the ampoule may be reused repeatedly. For example, by providing an injection port for injecting an injection solution into the ampoule and attaching an injection solution injector to the needleless syringe of the present invention, the injection solution in the ampoule can be repeatedly ejected and injected, allowing the ampoule to be used continuously without replacing it.

The needle-free syringe or needle-free injection system of the present invention is characterized by including, in addition to a machine casing main body to the front of which an ampoule can be attached, a piston provided on the machine casing main body so as to be slidable back and forth, and an elastic body that applies a forward force to the piston, an elastic body storage unit that stores energy in the elastic body by moving the piston rearward, a first actuator that drives the elastic body storage unit, a piston head stop position adjustment unit that adjusts the position at which the piston head stops when the stored elastic body is released to drive the piston forward, a second actuator that drives the piston head stop position adjustment unit, and a control unit that controls the first actuator and the second actuator.
The needle-free syringe or needle-free injection system of the present invention may further have a configuration other than that described above.
In the present invention, the above configuration may be divided among multiple devices, in which case it becomes a needle-free injection system. For example, but not limited to, the control unit may be a control device separate from the needle-free syringe main body, and the needle-free injection system may be one in which the needle-free syringe main body and the control device are connected by wire or wireless communication.

The "elastic body energy storage unit" provided in the needle-free syringe or needle-free injection system of the present invention is not particularly limited, and any mechanism may be used as long as it is capable of moving the piston rearward using the driving force of the actuator. Because the elastic body applies a forward force to the piston, moving the piston rearward causes the elastic body to deform (compress or expand in the case of a coil spring), thereby storing elastic energy.
In the present invention, "forward" means the direction in which the piston presses the plunger of the ampule on the axis along which the piston slides back and forth. Also, "rear" means the opposite direction to "forward."
The mechanism that can move the piston backward using the driving force of the actuator can be, for example, a mechanism that can convert the rotational motion of the actuator into linear motion, such as, but not limited to, a cam mechanism, a ball screw mechanism, a timing belt mechanism, a rack and pinion mechanism, etc.

The "elastic body energy storage unit" included in the needle-free syringe or needle-free injection system of the present invention can be given the function of releasing the force moving the piston backward, thereby releasing the energy of the elastic body. Alternatively, a mechanism separate from the "elastic body energy storage unit" can be used to hold the piston in position after it has moved backward, and then release the force to release the energy of the elastic body. Such a mechanism could include, but is not limited to, a trigger or safety lock mechanism such as that disclosed in Patent Document 1. However, if the piston that has moved backward is held by a trigger or safety lock mechanism, there is a risk that the trigger may be activated unexpectedly due to a malfunction, causing the injection liquid to be ejected, resulting in injury to the human body. Therefore, in the needle-free syringe or needle-free injection system of the present invention, it is preferable that, immediately after the user performs the injection operation, the elastic body energy storage unit move the piston backward, and then release the force to release the energy, successively within a short period of time.

The "piston head stop position adjustment unit" provided in the needle-free syringe or needle-free injection system of the present invention is a mechanism that adjusts the position at which the piston head stops when the stored elastic body is released to drive the piston forward (referred to as the "piston head stop position" in this invention). When the piston head presses the plunger to inject the injection liquid from the ampule, the plunger is pushed up to the position at which the piston head stops, injecting the injection liquid. Therefore, by adjusting the piston head stop position, it is possible to adjust the amount of injection liquid to be injected. The piston head stop position can be adjusted by using a piston with the following mechanism.
The piston used in the needle-free syringe or needle-free injection system of the present invention has a piston base to which a forward force is applied by an elastic body, and a piston rod equipped with a piston head. Here, the piston rod is connected so as to be able to receive a forward force from the piston base, so that the forward force received by the piston base from the elastic body can be transmitted to the piston rod, and the piston head equipped on the piston rod can press the plunger. At the same time, because the piston rod is connected to the piston base so that its forward/backward position relative to the piston base can be changed, it is possible to adjust the stop position of the piston head.
The method of connecting the piston rod and piston base is not particularly limited, and examples that can be used include, but are not limited to, a method of connecting using a male and female thread structure, or a method of connecting using a hydraulic cylinder structure.

The "actuator" included in the needle-free syringe or needle-free injection system of the present invention is not particularly limited, and any component or device capable of generating a driving force can be used as the actuator. Examples of actuators that can be used include, but are not limited to, servo motors, stepping motors, linear motors, hydraulic actuators, pneumatic actuators, ultrasonic motors, etc.
In the present invention, the elastic body storage unit is driven by the first actuator, and the piston head stop position adjustment unit is driven by the second actuator, but if a mechanism is used in which a single actuator can transmit driving force to both the elastic body storage unit and the piston head stop position adjustment unit, the first actuator and the second actuator may be the same actuator.

In the needle-free syringe or needle-free injection system of the present invention, the elastic body is charged by the elastic body charging unit and the piston head stop position is controlled by the piston head stop position adjustment unit. However, when continuously injecting injection liquid, manually repeatedly driving the elastic body charging unit places a heavy burden on the user. Furthermore, it is difficult to accurately control the piston head stop position by manually driving the piston head stop position adjustment unit. To prevent accidental injection of injection liquid when the user does not intend, it is preferable to perform a series of operations in a short period of time immediately after the user performs the injection operation, including moving the piston backward by the elastic body charging unit, adjusting the piston head stop position by the piston head stop position adjustment unit, and driving the piston forward by releasing the elastic body. However, it is impossible to perform these operations manually in a short period of time.
Therefore, the needle-free syringe or needle-free injection system of the present invention essentially comprises a first actuator that drives the elastic body energy storage unit, a second actuator that drives the piston head stop position adjustment unit, and a control unit that controls these, and these repeatedly charge the elastic body by the elastic body energy storage unit, change the piston head stop position forward by the piston head stop position adjustment unit, and drive the piston forward by releasing the elastic body.This makes it possible to gradually press and advance the plunger that pushes out the injection liquid in the ampule, and repeatedly inject the injection liquid in a single ampule in multiple doses.

1-2. First Embodiment Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.
FIG. 1 is a schematic diagram showing the internal structure of a needleless syringe according to a first embodiment of the present invention.
1, the needle-free syringe 1 of the present invention has a structure in which a machine casing main body 2 serves as the housing of the device, and various parts are attached inside the machine casing main body 2, such as a piston 5, an elastic body (coil spring) 6, an elastic body energy storage unit 7, a first actuator (motor) 8, a piston head stop position adjustment unit 9, a second actuator (motor) 10, and a control unit 11. An ampoule 3 can be attached to the front of the machine casing main body 2.
The machine frame main body 2 has a generally cylindrical shape overall, and has a plurality of steps at the front, giving it a shape similar to a plurality of stacked cylinders of different diameters.
In the first embodiment, the machine frame main body serves as the housing, but the present invention is not limited to this form and may be any machine frame main body as long as it can accommodate an ampoule at the front and has a piston attached thereto so as to be able to slide back and forth.

1-2-1. Ampoule As shown in FIG. 1, the front of the machine casing main body 2 is configured to allow attachment of an ampoule 3. The ampoule 3 is a disposable consumable item separate from the needleless syringe 1, and users purchase the ampoule 3 sealed in a sterilized package and use it by attaching it to the opening at the front of the machine casing main body 2. The ampoule 3 has a cylindrical cylinder 302 that contains an injection solution 301, and a discharge nozzle 303 with a small diameter is provided at its front end. A plunger 304 is inserted into the cylinder 302, and by pushing the plunger 304 in, the injection solution 301 contained inside the cylinder 302 can be ejected from the discharge nozzle 303.
A male thread 305 is formed at the rear of the cylinder 302, and is shaped to fit into the female thread 201 formed in the front opening of the machine casing main body 2. The ampoule 3 can be attached to the front opening of the machine casing main body 2 by fitting the male thread and the female thread together. The ampoule 3 is provided with an annular stopper 306. When the male thread 305 of the cylinder 302 is turned into the female thread 201, the stopper 306 abuts against the front of the machine casing main body 2. When the cylinder 302 is turned with even greater force, the stopper 306 generates an elastic force, increasing the frictional force and preventing the male thread 305 from rotating relative to the female thread 201. This prevents the ampoule 3 from loosening and also prevents the ampoule 3 from flying out due to the driving force of the piston.

1 , a cylindrical piston syringe 4 is attached to the machine casing main body 2, and a piston 5 is provided inside the piston syringe 4 so as to be able to slide back and forth. The piston 5 consists of a piston base 510 and a piston rod 520.
The piston base 510 has a cylindrical shape with its outer circumferential surface in contact with the inner circumferential surface of the piston syringe 4, and can slide back and forth inside the piston syringe 4. A groove in the front-rear direction (not shown) is provided on the inner circumferential surface of the piston syringe 4 as a piston guide, and a protrusion provided on the outer circumferential surface of the piston base 510 slides along the piston guide, preventing the piston base 510 from rotating.
A protruding piston follower 511 is provided on the piston base 510, and the piston follower 511 can receive a forward force from the elastic body (coil spring) 6. The piston follower 511 can also receive a rearward force from the cam 750 of the elastic body energy storage unit 7, which moves the piston base 510 rearward.
A plurality of washers 512 can be attached to the piston base 510 adjacent to the piston follower 511, and the injection force (injection pressure) can be adjusted by changing the length of the elastic body (coil spring) 6 when the piston base is moved rearward. The elastic body (coil spring) 6 is compressed between the washers 512 and the machine casing main body 2, so when the piston base is moved rearward a certain distance, the more washers 512 there are, the more the elastic body (coil spring) 6 is compressed and the shorter its length becomes, and therefore, a larger amount of elastic energy can be stored, and the injection force (injection pressure) can be increased.

The piston base 510 and the piston rod 520 are connected to each other by threading a female thread 513 of the piston base 510 into a male thread 521 of the piston rod 520. As a result, the piston rod 520 can receive a forward force from the piston base 510, which receives force from the elastic body (coil spring) 6. Because a piston head 522 is provided at the front end of the piston rod 520, the forward force applied by the elastic body (coil spring) 6 is also transmitted to the piston head 522. In FIG. 1, the "forward direction" is indicated by the direction of the arrow.
Therefore, when the piston base 510 is driven forward by the force of the elastic body (coil spring) 6, the piston head 522 presses the plunger 304, causing the injection liquid 301 in the ampoule 3 to be ejected from the discharge nozzle 303.

The piston base 510 and the piston rod 520 are connected to each other by a structure of the female thread 513 and the male thread 521, so that the relative positions of the piston base 510 and the piston rod 520 can be changed forward and backward by rotating them relative to each other, thereby adjusting the position of the piston head 522 forward and backward.
In the first embodiment, the piston base 510 is provided with a piston guide (not shown) to prevent the piston base 510 from rotating, while the piston rod 520 can rotate by the driving force of the second actuator (motor) 10. However, the present invention is not limited to this configuration, and a structure in which the piston rod does not rotate and the piston base rotates instead may be used. Also, as described above, the present invention may have any structure as long as the piston rod can receive a forward force from the piston base and is connected to the piston base so that its forward/backward position relative to the piston base can be changed.

As shown in Fig. 1, the needle-free syringe 1 of the present invention is provided with the elastic body energy storage unit 7, and the cam 750 of the elastic body energy storage unit 7 presses the piston follower 511 to move the piston base 510 rearward, compressing and storing the elastic body (coil spring) 6.
The elastic energy storage unit 7 includes a rod 710 , a ball bearing 720 , a gear wheel 730 , a base 740 and a cam 750 .
The rod 710 is a cylindrical part that serves as the axis of rotation for rotating the gear wheel 730. The rod 710 is hollow, allowing the piston rod 520 to move freely back and forth within the hollow space. The rod 710 is inserted into a cylindrical ball bearing 720 and contacts the inner surface of the ball bearing 720 via balls, allowing for smooth rotation. The gear wheel 730 is connected to the rod 710, and the gear wheel 730 rotates around the rod 710 as its axis of rotation. The rod 710 and the gear wheel 730 rotate around the axis of the front-rear direction along which the piston slides. The ball bearing 720 contacts the gear wheel 730 via balls, allowing the gear wheel 730 to rotate smoothly without being subjected to large frictional forces. The gear wheel 730 is provided with an annular base 740, and a cam 750 is provided on the surface of the base 740. As a result, the cam 750 also rotates around the axis of the front-rear direction.

The large gear 730 can rotate by receiving the driving force of the first actuator (motor) 8. That is, the rotational driving force of the first actuator (motor) 8 is transmitted to the large gear 730 by a gear 810 provided on the shaft 820 of the first actuator (motor) 8.

In order to explain the transmission of driving force by gears, a cross-sectional view taken along the plane including the dashed line C1-C2 in FIG. 1 is shown in FIG. 2(A).
2A, rod 710 is cylindrical and has a space inside that allows free movement of piston rod 520. A large gear 730 is connected to rod 710, and a large number of teeth 731 are provided on the outer periphery of large gear 730.
A gear 810 for rotating the large gear 730 is installed on the upper part of the large gear 730, and rotates around a shaft 820 by the driving force of the first actuator (motor) 8. A large number of teeth 811 are provided on the outer periphery of the gear 810.
When gear 810 rotates clockwise, at the portion where gear 810 and large gear 730 mesh, teeth 811 of gear 810 moving leftward press teeth 731 of large gear 730 leftward, causing large gear 730 to rotate counterclockwise. Conversely, when gear 810 rotates counterclockwise, large gear 730 rotates clockwise. The drive of first actuator (motor) 8 is controlled by control unit 11, making it possible to freely control the rotation of large gear 730.

As shown in FIG. 2A, the large gear 730 and the gear 810 are housed inside the cylindrical machine casing main body 2, which can prevent accidents such as being caught between the gears.
The lower part of the machine casing main body 2 has a flat shape, allowing the needle-free syringe 1 to be placed stably on a workbench, etc. The machine casing main body 2 has two left and right parts joined together by fastening screws (not shown), and internal parts can be replaced or repaired by removing the fastening screws.

The cam 750 shown in FIG. 1 is a mechanism that can convert the rotational movement of the large gear 730 into the back-and-forth movement of the piston.
As shown in FIG. 1 , cam 750 abuts against piston follower 511 of piston base 510. Cam 750 has a semicircular, three-dimensional shape with thickness varying depending on the location. Because piston follower 511 abuts against cam 750 via a ball, cam 750 can rotate smoothly. Because piston base 510 is prevented from rotating by a piston guide (not shown), the point where cam 750 abuts against piston follower 511 moves on cam 750. As cam 750 rotates, the thickness of cam 750 in the front-to-rear direction at the point where it abuts against piston follower 511 changes, so that rotational motion can be converted into front-to-rear motion.

FIG. 3 shows the state in which the cam 750 and the piston follower 511 are in contact with each other, and the change in the thickness of the cam.
3A is a schematic diagram showing the state in which the cam 750 and the piston follower 511 are in contact with each other, as viewed from behind along the axis along which the piston in FIG. 1 slides.
3A, a circular base 740 is provided on the large gear 730, and a cam 750 is provided on the surface of the base 740. The cam 750 has a semicircular, three-dimensional shape with a variable thickness, and a pair of cams 750 of the same shape are formed on the base 740 at 180° angle from each other.
A pair of piston followers 511 provided at the tip of the piston base 510 each abut against a cam 750, and the piston followers 511 are pressed against the cam 750 by an elastic body (coil spring) 6. Therefore, the piston base 510 moves back and forth depending on the thickness of the cam at the point where the cam 750 and the piston followers 511 abut. When the piston base 510 moves back and forth, the piston rod 520 connected to the piston base 510 also moves back and forth.
There are two points where the cam 750 and the piston follower 511 come into contact, but since the two cams 750 have the same three-dimensional shape, the thickness of the cam 750 at the points where the cam 750 and the piston follower 511 come into contact is the same at both points.
The thickness of the cam 750 at the point where the cam 750 and the piston follower 511 contact each other varies with the rotation of the gear wheel 730. The angle by which the gear wheel 730 has rotated is indicated by the symbol θ.

FIG. 3B is a graph showing the change in thickness of the cam 750 at the point where the cam 750 and the piston follower 511 come into contact when the large gear 730 rotates.
As shown in Figure 3(B), when the rotation angle θ of the gear 730 is 0°, the thickness of the cam 750 is 0, and the piston follower 511 abuts against the base 740. When the gear 730 rotates and the rotation angle θ becomes 15°, the piston follower 511 first abuts against the cam 750, and as the rotation angle increases further, the thickness of the cam 750 at the point where the cam 750 and the piston follower 511 abut increases. Then, when the rotation angle θ becomes 150°, the thickness of the cam 750 reaches its maximum value, G. Figure 3(A) shows the state when the rotation angle θ of the gear 730 is 150°.
As the thickness of the cam increases in this way, the piston base 510 moves rearward, compressing the elastic body (coil spring) 6 and allowing the elastic body energy storage section 7 to store energy in the elastic body.

3(B), as the rotation angle is further increased, the thickness of cam 750 suddenly decreases to 0 when rotation angle θ=165°. In this way, cam 750 has a stepped shape, and piston follower 511 suddenly drops from this step, receives a force that causes elastic body (coil spring) 6 to return to its original shape, accelerates, and is driven forward at high speed, before stopping when it reaches base 740. In this way, elastic body energy storage unit 7 can also release energy from elastic body (coil spring) 6, thereby allowing piston 5 to be driven forward at high speed.
As described above, the elastic body energy storage unit 7 included in the needle-free syringe 1 of the first embodiment is a cam mechanism that can convert the rotational motion of the first actuator (motor) 8 into forward and backward motion of the piston, and by continuing the rotational motion, the elastic body (coil spring) 6 can be continuously charged and released.

1-2-4. Piston head stop position adjustment unit As shown in Fig. 1, the needle-free syringe 1 of the present invention is equipped with a piston head stop position adjustment unit 9, which rotates the piston rod 520 using the driving force of the second actuator (motor) 10 to change the relative position of the piston rod 520 with respect to the piston base 510 back and forth, thereby adjusting the piston head stop position.
As shown in FIG. 1 , the piston head stop position adjustment unit 9 is a mechanism including an internal gear 910 and a ball bearing 920. The internal gear 910 is cylindrical and has multiple teeth 911 that extend linearly in the front-to-rear direction and are provided facing inward to form an internal gear. In contrast, the rear end of the piston rod 520 has multiple teeth 523 that extend linearly in the front-to-rear direction and are provided facing outward to form a spur gear that meshes with the teeth 911 of the internal gear 910. The internal gear 910 is inserted into the ball bearing 920 to enable smooth rotation, and is further connected to the shaft 1001 of the second actuator 10 so that it can rotate using the driving force of the second actuator 10. With this structure, the rotational driving force of the second actuator (motor) 10 can be transmitted to the spur gear of the piston rod 520 via the internal gear 910, thereby rotating the piston rod 520. The drive of the second actuator (motor) 10 is controlled by the control unit 11, and the rotation of the internal gear 910 can be freely controlled in either direction.

In order to explain the transmission of driving force by the gears, a cross-sectional view taken along the plane including the dashed line C3-C4 in FIG. 1 is shown in FIG. 2(B).
2(B), the internal gear 910 has a cylindrical shape and houses the piston rod 520 therein. A plurality of teeth 911 are provided on the inside of the internal gear 910, and are configured to mesh with teeth 523 provided on the outside of the piston rod 520. Therefore, when the internal gear 910 is rotated clockwise by the second actuator (motor) 10, the piston rod 520 also rotates clockwise. Conversely, when the internal gear 910 is rotated counterclockwise, the piston rod 520 also rotates counterclockwise.
The teeth 911 of the internal gear 910 and the teeth 523 of the piston rod 520 both have tooth traces that extend linearly in the front-to-rear direction, so that the piston rod 520 can slide back and forth relative to the internal gear 910 .

1 , the male thread 521 provided on the piston rod 520 is cut to be a right-handed thread, so when the internal gear 910 is rotated clockwise, the piston rod 520 also rotates clockwise and moves forward relative to the piston base 510. Conversely, when the internal gear 910 is rotated counterclockwise, the piston rod 520 also rotates counterclockwise and moves backward relative to the piston base 510.
In the first embodiment, the male thread 521 is cut to be a right-handed thread, but in the needle-free syringe of the present invention, it may be cut to be a left-handed thread. In this case, when the piston rod 520 is rotated counterclockwise, it moves forward relative to the piston base 510, and when it is rotated clockwise, it moves backward.

1 shows a state in which the piston base 510 has moved rearward by the cam 750, storing energy in the elastic body (coil spring) 6, and FIG. 3B shows a state in which the rotation angle θ of the gear wheel 730 is 150°. If the gear wheel 730 is further rotated and the rotation angle θ exceeds 165°, as described above, the piston follower 511 suddenly drops from the step of the cam 750, releasing the energy of the elastic body (coil spring) 6, and the piston 5 is driven forward at high speed, after which it stops when the piston follower 511 reaches the base 740. The position of the piston head 522 at this point of stop is the "piston head stop position."
In the case of FIG. 1, the distance (gap) between the piston head 522 and the plunger 304 is G, but the height of the cam 750 is also G. Therefore, even if the elastic body (coil spring) 6 is released, the piston head stops at the end position of the plunger 304, and the piston head 522 cannot press the plunger 304.

Therefore, in order to press the plunger 304 and inject the injection liquid 301, it is necessary to change the piston head stop position to a position in the forward direction.
This position change can be performed by the piston head stop position adjustment unit 9. That is, the control unit 11 shown in Fig. 1 controls the second actuator (motor) 10 to rotate the internal gear 910 clockwise a predetermined amount (a predetermined number of rotations) and move the piston rod 520 forward by a distance x. This allows the piston head stop position to be changed to a position moved forward by the distance x compared to the case of Fig. 1.
When the piston rod 520 is moved forward by the distance x, the position of the piston head 522 is measured in real time by a piston rod position sensor 1301 connected to the control unit 11 via an electric communication line (not shown) by detecting the approach of the piston head 522. When the control unit 11 measures that the piston head 522 has moved forward beyond a predetermined position, it immediately stops driving the second actuator (motor) 10 to stop the movement of the piston rod 520. This prevents the piston rod 520 from moving forward beyond the distance x, thereby injecting an excessive amount of liquid, and also prevents an accident in which the piston rod 520 moves too far forward and the piston head 522 jumps out forward during injection, damaging the ampoule 3 or the front end of the machine housing main body 2.

FIG. 4 shows the operation of the internal structure of the needle-free syringe 1 when the piston head stop position is changed and the elastic body is released.
FIG. 4A shows a state in which the piston head has moved forward from the state shown in FIG. 1 . As shown in FIG. 4A , compared to FIG. 1 , the piston head 522 has moved forward by a distance x, and the distance (gap) between the piston head 522 and the plunger 304 has changed from G to G-x. Meanwhile, the position of the piston base 510 has not changed, and the relative position of the piston rod 520 with respect to the piston base 510 has moved forward by a distance x. Because FIG. 4A shows a state before the elastic body (coil spring) 6 is released, the position of the piston head 522 shown in FIG. 4A is not the "piston head stop position" according to the present invention. However, because the piston head 522 has moved forward by a distance x, the position at which the piston head stops when the elastic body (coil spring) 6 is released and the piston is driven forward (the "piston head stop position") has also moved forward by a distance x.

FIG. 4B shows a state in which the piston 5 has stopped after being driven forward by releasing the elastic body (coil spring) 6 from the state shown in FIG. 4A.
As shown in FIG. 4(B), the thickness of the cam at the point where the piston follower 511 abuts disappears, and the piston follower 511 abuts against the base 740. This corresponds to the state in FIG. 3(B) where the rotation angle θ of the gear wheel 730 is 180°. As described above, when the rotation angle θ of the gear wheel 730 exceeds 165°, the piston follower 511 suddenly drops from the step of the cam 750, the elastic body (coil spring) 6 is released, the piston 5 is driven forward at high speed, and then the piston follower 511 stops when it reaches the base 740. At this time, as shown in FIG. 4(B), the piston head 522 collides with the plunger 304 at high speed, and the injection solution 301 can be ejected from the discharge nozzle 303 at high speed.

As shown in Figure 4 (B), the needle-free syringe 1 is equipped with a piston base position sensor 1302 connected to the control unit 11 via an electrical communication line (not shown). The piston base position sensor 1302 measures the position of the piston follower 511 in real time by detecting the approach of the piston follower 511. Then, when it measures that the piston base 510 has moved forward to a position where the piston follower 511 abuts the base 740, the control unit 11 immediately stops driving the first actuator (motor) 8. This makes it possible to stop the rotation of the large gear 730 at the correct position after injection is completed, and also prevents the accident of an unintended next injection.

4A, because a gap exists between the piston head 522 and the plunger 304, in the initial stage of the release of the elastic body (coil spring) 6, the piston 5 is accelerated by the elastic body (coil spring) 6 without resistance and can collide with the plunger 304 at high speed. As a result, the plunger 304 also moves at high speed, and the piston head 522 pushes the plunger 304 in one go until the piston follower 511 reaches the base 740 and stops, thereby injecting the injection solution 301. In this way, because of the existence of the gap, the piston head 522 acts like a hammer hitting the plunger 304, allowing the injection solution to be injected at high speed, making it possible to inject the injection solution subcutaneously.
The gap distance in Figure 4(A) is G-x, but the piston head 522 moves forward by the cam thickness G and stops, so that the plunger 304 can be pushed in by a distance x, as shown in Figure 4(B). Therefore, by controlling the distance x by which the piston head 522 is moved forward by the control unit 11, the amount of injection liquid per injection (x x cross-sectional area of the injection liquid 301 in the ampule 3) can be controlled. Furthermore, by determining the amount of injection liquid per injection, the number of times that the injection liquid 301 in a single ampule 3 can be injected (the length of the injection liquid 301 in the ampule 3 in the front-to-rear direction/x) is also determined.

The larger the value of the distance x by which the piston head 522 is moved forward, the larger the amount of injection liquid per injection, but the shorter the gap distance (G-x), the shorter the distance over which the piston head 522 is accelerated, and the weaker the initial impact force (injection pressure). Conversely, when the value of x is small, the amount of injection liquid per injection decreases, but the longer the gap distance (G-x), the longer the distance over which the piston head 522 is accelerated, and the stronger the initial impact force (injection pressure).
In areas where the skin is elastic and prone to bending (flexing), even if the initial impact force (injection pressure) is strong, if the amount of injection liquid is small, the amount of injection liquid will run out before the skin bends, and the skin will not be able to be penetrated. Therefore, it is effective to increase the value of x to increase the amount of injection liquid, and to further push the injection liquid into the bent skin, thereby penetrating the skin.
Conversely, in areas where the skin is taut and hard, even if the amount of injection solution is large, if the initial impact force (injection pressure) is weak, the hard skin cannot be penetrated. Therefore, it is effective to increase the initial impact force (injection pressure) by decreasing the value of x, thereby breaking through the hard skin and allowing the injection solution to penetrate.

The elastic body (coil spring) 6, which was compressed as shown in Figure 4(A) due to the energy storage of the elastic body, returns to its original state and becomes longer as shown in Figure 4(B) when the elastic body is released. As shown in Figure 4(B), the piston follower 511 is stopped in contact with the base 740, so the piston 5 does not move forward any further, and the plunger 304 is not pushed any further by the piston head 522. Therefore, after a single injection of the injection liquid has been completed, the needle-free syringe 1 can be safely placed on standby without the risk of accidental injection by maintaining the state shown in Figure 4(B).

When the injection liquid is next to be injected, the second injection can be performed by successively performing in a short time the step of energizing the elastic body as shown in Fig. 1, the step of changing the piston head stop position as shown in Fig. 4(A), and the step of deenergizing the elastic body as shown in Fig. 4(B). Note that in the second injection, each step is performed with the position of the piston head 522 further moved forward by x compared to Fig. 1 and Figs. 4(A) and (B).
The third and subsequent injections can also be performed using this series of steps. By repeating this series of steps multiple times, it is possible to repeatedly inject the injection liquid in a single ampoule in multiple doses.

After the injection liquid in the ampoule 3 has been completely injected, the second actuator (motor) 10 is driven in the reverse direction to rotate the internal gear 910 counterclockwise a predetermined amount (a predetermined number of rotations), and the piston rod 520 moves backward and returns to its initial position. Thereafter, the empty ampoule 3 is removed and a new ampoule 3 filled with the injection liquid 301 is attached, making it possible to inject the injection liquid again.
When moving the piston rod 520 rearward to return it to its initial position, the position of the piston rod 520 is measured in real time by the piston rod position sensor 1301, and when it is determined that the piston rod 520 has moved rearward from its initial position, the control unit 11 immediately stops driving the second actuator (motor) 10 to stop the rearward movement of the piston rod 520. This prevents an accident in which the piston rod 520 moves too far rearward and the rear end of the piston rod 520 collides with the bottom of the internal gear 910 when storing energy in the elastic body (coil spring) 6, resulting in damage to parts.

1 , the needle-free syringe 1 of the first embodiment includes a control unit 11, which controls the driving of the first actuator (motor) 8 and the second actuator (motor) 10. From the control unit 11 to the first actuator (motor) 8, power and a command signal for controlling the actuator are supplied via a cable 1101. Similarly, from the control unit 11 to the second actuator (motor) 10, power and a command signal for controlling the actuator are supplied via a cable 1102. Power is supplied to the control unit 11 from the outside via a power cable 14, and the control unit 11 uses the power from the outside to process information and supply power to the first actuator (motor) 8 and the second actuator (motor) 10.

The first actuator (motor) 8 and the second actuator (motor) 10 each include a drive circuit, a control circuit, and a rotation speed detector (not shown). Based on a command signal supplied from the control unit 11 and a detection signal measured by the rotation speed detector, the control circuit calculates the voltage required to change the current motor rotation speed per unit time, as determined by the detection signal, to the rotation speed per unit time specified by the command signal, thereby generating a drive voltage signal and supplying it to the drive circuit. Based on the drive voltage signal received from the control circuit, the drive circuit applies voltage to the actuator to drive the actuator.
The control unit 11 generates a command signal using an information processing device (not shown). The information processing device performs predetermined information processing according to commands of a control program stored in a storage device (not shown), and generates the command signal.

In the first embodiment, the control unit 11 supplies command signals to the first actuator (motor) 8 and the second actuator 10 to control the drive of these actuators, but the needle-free syringe or needle-free injection system, and drive method and control program of the present invention are not limited to this aspect, and for example, the drive of the actuators may be controlled by supplying a voltage-controlled current from the control unit 11 to the actuators. Furthermore, in the first embodiment, the command signals are generated by the information processing device and control program possessed by the control unit 11, but the needle-free syringe or needle-free injection system and drive method of the present invention are not limited to this aspect, and for example, the actuators may be controlled by only a control circuit and drive circuit, without using an information processing device or control program.

As shown in FIG. 1, the control unit 11 is provided with an ejection button 1201 and an ejection liquid amount changeover switch 1202 as an interface that allows the user to operate and set the needle-free syringe 1.
When the user presses the ejection button 1201, the control unit 11 receives the signal and drives the first actuator (motor) 8 and the second actuator (motor) 10 to perform the following steps 1A) to 1C) consecutively in a short period of time.
1A) A step of driving the first actuator (motor) 8 to move the piston base 510 rearward by the elastic body energy storage unit 7, thereby storing energy in the elastic body (coil spring) 6;
1B) A step of driving the second actuator (motor) 10 to move the relative position of the piston rod 520 with respect to the piston base 510 forward by a distance x using the piston head stop position adjustment unit 8;
1C) A step of further driving the first actuator (motor) 8, discharging the elastic body (coil spring) 6 by the elastic body energy storage unit 7, driving the piston 5 forward, and pressing the plunger 304 with the piston head 522, thereby injecting the injection liquid 301 in the ampoule 3;
In this way, the user can automatically inject the injection liquid with the simple operation of pressing the injection button 1201 of the needle-free syringe 1.
The user can then repeatedly inject the injection liquid from a single ampule by pressing the injection button 1201 multiple times, thereby enabling the injection liquid to be injected in multiple separate doses. Also, if the user presses the injection button 1201 multiple times in succession each time the injection liquid is to be injected, the user can easily and automatically shoot the injection liquid in rapid succession using the driving force of the actuator, without having to repeatedly compress the elastic body (coil spring) 6 manually (by hand).

The control unit 11 can simultaneously execute the above-mentioned steps 1A) and 1B) upon receiving a signal that the user has pressed the injection button 1201. This can shorten the injection time.
1, the piston base 510 is moved rearward, while in step 1B), the piston head stop position adjustment unit 8 moves the position of the piston rod 520 forward relative to the piston base 510. Therefore, if the speed at which the piston rod 520 moves forward relative to the piston base 510 in step 1B) is made faster than the speed at which the piston base 510 moves rearward in step 1A, when steps 1A) and 1B) are performed simultaneously, the piston head 522 moves forward and presses the plunger 304, which may cause the injection solution 301 to leak before injection.
To prevent this, the control unit 11 drives the first actuator (motor) 8 and the second actuator (motor) 10 so that the speed at which the piston rod 520 moves forward relative to the piston base 510 in step 1B) is slower than the speed at which the piston base 510 moves backward in step 1A).
Alternatively, the position of the piston rod 520 may be measured in real time by the piston rod position sensor 1301, and when it is determined that the piston rod 520 has moved forward from a predetermined position, the control unit 11 may immediately stop driving the second actuator 10.

The user can use the injection volume changeover switch 1202 to set the volume of injection liquid per injection to either "0.05 ml" or "0.1 ml."
If the amount of injection liquid per injection is set to "0.05 ml," the distance x by which the piston head stop position is moved forward in step 1B) is set to "x (cm) = 0.05 ml (cm ³ ) / cross-sectional area of injection liquid 301 (cm ² )." The drive amount of the second actuator (motor) 10 is controlled to move the piston head stop position forward so as to achieve the set distance x. As a result, when the elastic body (coil spring) 6 is released, the piston head 522 pushes the plunger 304 into the ampoule 3 by the distance x, and the amount of injection liquid injected is 0.05 ml (= x × cross-sectional area of injection liquid 301). Since the amount of injection liquid filled in the ampoule is 0.4 ml, eight injections can be performed.
When the amount of injection liquid per injection is set to "0.1 ml", the distance x is set to "x (cm) = 0.1 ml (cm ³ ) / cross-sectional area of injection liquid 301 (cm ² )", which means that the plunger 304 is pushed in twice as far as when the amount of injection liquid is set to "0.05 ml", and the amount of injection liquid injected is "0.1 ml". The number of times that the injection liquid can be injected is four, which is half the number of times compared to when the amount of injection liquid per injection is set to "0.05 ml".

1-2-6. Control Program In the control unit 11 provided in the needle-free syringe 1 of the first embodiment, as explained in the section " 1-2-5. Control Unit ", the information processing device performs predetermined information processing in response to commands from the control program and generates a command signal.
Specifically, the control program causes the information processing device to execute information processing including the following steps 1A') to 1C') as essential steps.
1A') A step of generating a command signal to drive the first actuator (motor) 8 by a predetermined amount (predetermined number of rotations) in order to store energy in the elastic body (coil spring) 6;
1B') generating a command signal to drive the second actuator (motor) 10 by a predetermined amount (predetermined number of rotations) to change the piston head stop position to a predetermined distance x in the forward direction;
1C') A step of generating a command signal to drive the first actuator (motor) 8 by a predetermined amount (predetermined number of rotations) in order to release the elastic body (coil spring) 6;

The control program in the first embodiment includes an injection control program that controls the operation of injecting an injection solution in response to the user's operation of an injection button. More specifically, this injection control program causes an information processing device to execute the information processing shown in the flowchart of FIG.
As shown in Fig. 5, the flow of information processing by the injection control program in the first embodiment begins with "Start." When the power cable 14 of the needle-free syringe 1 shown in Fig. 1 is inserted into a power outlet (not shown) and a start button (not shown) is pressed, the information processing device provided in the control unit 11 starts up and starts information processing by the injection control program.

5 is a step of performing information processing to detect a user's operation of the ejection button 1201. In the information processing of step S01, if a signal indicating that the ejection button 1201 has been pressed is not received (in the case of "No"), the process waits by repeating detection, and if a signal indicating that the ejection button 1201 has been pressed is received (in the case of "Yes"), the process proceeds to the next step S02A.
Step S02A is an essential step corresponding to the above-mentioned step 1A'), and is a step for performing information processing to generate a command signal for driving the first actuator (motor) 8 by a predetermined amount (predetermined number of rotations) in order to store energy in the elastic body (coil spring) 6.
Here, the predetermined amount (predetermined number of rotations) for driving the first actuator (motor) 8 is the number of rotations of gear 810 required to rotate large gear 731 shown in Fig. 2A by 180°. The command signal is a signal that commands the number of rotations of the motor per unit time, and by generating this command signal for a predetermined time and sending it to first actuator (motor) 8, it becomes possible to drive the first actuator (motor) 8 by the predetermined amount (predetermined number of rotations).
5, a command signal is generated and transmission of the command signal to the first actuator (motor) 8 is started, thereby starting the driving of the first actuator (motor) 8. After the command signal is generated and transmission of the command signal is started in step S02A, the process proceeds to the next step S03B.

Step S03B shown in FIG. 5 is a necessary step corresponding to step 1B') described above, and is a step for performing information processing to generate a command signal for driving the second actuator (motor) 10 by a predetermined amount (predetermined number of rotations) in order to change the piston head stop position forward by a predetermined distance x.
As explained in the section " 1-2-5. Control Unit ," the distance x is determined to a different value depending on whether the injection volume per injection is set to "0.05 ml" or "0.1 ml." When the internal gear 910 shown in FIG. 1 is rotated clockwise, the piston rod 520 also rotates clockwise, causing the piston rod 520 to move forward relative to the piston base 510. The number of rotations of the internal gear 910 required to move the piston rod 520 forward by the distance x is the "predetermined amount (predetermined number of rotations)" in step S03B. Therefore, in step S03B, the set value for the injection volume per injection is read from the storage device, and information processing is performed to determine the required number of rotations of the internal gear 910 corresponding to the set value, followed by information processing to generate a command signal.
The command signal is a signal that commands the number of rotations of the motor per unit time, and in step S03B, the command signal is generated for a predetermined time and sent to the second actuator (motor) 10, thereby enabling it to be driven by a predetermined amount (predetermined number of rotations).
When a command signal is generated in step S03B shown in FIG. 5 and transmission of the command signal to the second actuator (motor) 10 is started, the second actuator (motor) 10 is also driven in addition to the first actuator (motor) 8, and the elastic body (coil spring) 6 is charged with energy and the piston head stop position is shifted forward simultaneously.
After generating a command signal in step S03B and starting transmission of the command signal, the process proceeds to the next step S041.

Steps S041, S051, S042 and S052 shown in FIG. 5 are steps for performing information processing to determine the timing to stop driving the first actuator (motor) 8 and the second actuator (motor) 10.
In step S041, information processing is performed to determine whether the first actuator (motor) 8 has been driven a predetermined amount (predetermined number of rotations). Specifically, the information processing determines whether a predetermined time has elapsed since the command signal generated in step S02A was sent to the first actuator (motor) 8. If the predetermined time has not elapsed, the first actuator (motor) 8 has not been driven a predetermined amount (predetermined number of rotations), resulting in a "Yes" determination, and the process proceeds to step S051. Conversely, if the predetermined time has elapsed, the first actuator (motor) 8 has been driven a predetermined amount (predetermined number of rotations), resulting in a "No" determination, and the process proceeds to step S061, where generation of the command signal for driving the first actuator (motor) 8 is stopped. This stops the driving of the first actuator (motor) 8.
Step S051 is a step of performing information processing to determine whether the second actuator (motor) 10 has been driven a predetermined amount (predetermined number of rotations) or whether the piston head 522 has moved forward a distance x. Specifically, the information processing determines whether a predetermined time has elapsed since the command signal generated in step S03B was transmitted to the second actuator (motor) 10. At the same time, based on position information of the piston head 522 measured by the piston rod position sensor 1301 shown in FIG. 1 , the distance the piston head 522 has moved forward is calculated compared to the distance before the command signal for driving the second actuator (motor) 10 was generated, and the information processing determines whether this value has reached x. Then, as shown in FIG. 5 , if it is determined that the second actuator (motor) 10 has not been driven a predetermined amount (predetermined number of rotations) and the piston head 522 has not moved forward a distance x, the determination is made "No" and the process returns to step S041. Otherwise, that is, if it is determined that the second actuator (motor) 10 has been driven a predetermined amount (a predetermined number of rotations) or that the piston head 522 has moved forward by the distance x, the determination is "Yes," and the process proceeds to step S071, where the generation of the command signal for driving the second actuator (motor) 10 is stopped. As a result, the driving of the second actuator (motor) 10 is stopped.
As described above, the information processing of steps S041 and S051 is repeated until either the first actuator (motor) 8 or the second actuator (motor) 10 is stopped.

5, if the drive of the first actuator (motor) 8 is stopped, the process proceeds to the next step S052, where a determination is made by information processing similar to that of step S051. If the determination in step S052 is "Yes," the process proceeds to step S072, where the generation of a command signal for driving the second actuator (motor) 10 is stopped. This stops the drive of the second actuator (motor) 10, and the drive of both the first actuator (motor) 8 and the second actuator (motor) 10 is stopped.
On the other hand, if the drive of the second actuator (motor) 10 is stopped first in step S071, the process proceeds to the next step S042, where a determination is made by information processing similar to that in step S041. If the determination in step S042 is "Yes," the process proceeds to step S062, where the generation of a command signal for driving the first actuator (motor) 8 is stopped. This causes the drive of both the first actuator (motor) 8 and the second actuator (motor) 10 to be stopped.

As described above, steps S041, S051, S042, and S052 make it possible to appropriately determine the timing to stop driving the first actuator (motor) 8 and the second actuator (motor) 10. This makes it possible to stop driving the first actuator (motor) 8 at the timing when energy storage of the elastic body (coil spring) 6 is completed, and also makes it possible to stop driving the second actuator (motor) 8 at the timing when shifting of the piston head stop position to a position in the forward direction by the predetermined distance x is completed.
In the injection control program of the first embodiment, as in steps S051 and S052, it is determined whether the piston head 522 has moved forward by the distance x based on the position information of the piston head 522 measured by the piston rod position sensor 1301. However, this determination is not essential, and the timing to stop the second actuator (motor) 10 can be appropriately determined simply by determining whether the second actuator (motor) 10 has driven a predetermined amount (predetermined number of rotations). In addition to this determination, the injection control program of the first embodiment performs a double determination, which also includes a determination based on the position information measured by the piston rod position sensor 1301. This prevents an accident in which the piston head 522 jumps forward during injection and damages the ampoule 3 or the front end of the machine casing main body 1, thereby improving the safety of the needleless syringe 1.

After the driving of both the first actuator (motor) 8 and the second actuator (motor) 10 has been stopped in step S062 or step S072 shown in FIG. 5, the process proceeds to step S08C.
Step S08C is an essential step corresponding to the above-mentioned step 1C'), and is a step for generating a command signal for driving the first actuator (motor) 8 by a predetermined amount (predetermined number of rotations) in order to release the energy of the elastic body (coil spring) 6.
Here, the predetermined amount (predetermined number of rotations) for driving first actuator (motor) 8 is the number of rotations of gear 810 required to rotate large gear 730 shown in Fig. 2A by 180°. The command signal is a signal that commands the number of rotations of the motor per unit time, and by generating this command signal for a predetermined period of time and transmitting it to first actuator (motor) 8, it becomes possible to drive the first actuator (motor) 8 by the predetermined amount (predetermined number of rotations). After generating the command signal and starting transmission of the command signal in step S08C, the process proceeds to the next step S09.

5 is a step for performing information processing to determine the timing to stop driving the first actuator (motor) 8. In step S09, information processing is performed to determine whether the first actuator (motor) 8 has been driven a predetermined amount (predetermined number of rotations) or whether the piston follower 511 has come into contact with the base.
Specifically, the information processing determines whether a predetermined time has elapsed since the command signal generated in step S08C was transmitted to the first actuator (motor) 8. At the same time, the information processing determines whether the piston follower 511 has reached a position where it contacts the pedestal 740, based on position information of the piston follower 511 measured by the piston base position sensor 1302 shown in FIG. 1. Then, if the information processing in step S09 determines that the first actuator (motor) 8 has not been driven by a predetermined amount (predetermined number of rotations) and that the piston follower 511 has not reached a position where it contacts the pedestal 740 (if the determination is "No"), the information processing of step S09 is repeated. In other cases, that is, when it is determined that the first actuator (motor) 8 has been driven a predetermined amount (a predetermined number of rotations) or when it is determined that the piston follower 511 has reached a position where it abuts against the pedestal 740, the determination is "Yes" and the process proceeds to step S10, where the generation of a command signal for driving the first actuator (motor) 8 is stopped. This makes it possible to stop driving the first actuator (motor) 8 at an appropriate timing when the ejection of the injection solution 301 due to the release of the elastic body (coil spring) 6 is completed.

In the injection control program of the first embodiment, as described above, in step S09, it is determined whether the piston follower 511 has reached a position where it abuts the base 740, based on the position information of the piston follower 511 measured by the piston base position sensor 1302. However, this determination is not essential, and the timing to stop the first actuator (motor) 8 can be appropriately determined simply by determining whether the first actuator (motor) 8 has been driven a predetermined amount (predetermined number of rotations). In addition to this determination, the injection control program of the first embodiment also makes a determination based on the position information measured by the piston base position sensor 1302, making a double determination. This prevents the large gear 730 shown in FIG. 4 from continuing to rotate after injection is completed, which could lead to an unintended next injection, and improves the safety of the needle-free syringe 1.

After the driving of the first actuator (motor) 8 is stopped in step S10 shown in FIG. 5, the process proceeds to the next step S11, where information processing is performed to add 1 to the value of variable s that counts the number of injections.
The variable s that counts the number of injections is recorded in an information storage device provided in the control unit 11. The variable s is used to count and display the number of injections. Specifically, an injection count display program that is part of the control program reads out the variable s and displays the number of injections that have been made since a new ampoule was set up to the present time, together with the number of injections that can be made with a single ampoule ("8 times" or "4 times"), on a liquid crystal display device (not shown) provided in the needle-free syringe 1. This allows the user to know the number of injections that have been given to patients and the number of injections that can be made remaining with the same ampoule.
The variable s is also used for information processing required for operations after injection. Specifically, when the information processing in step S11 shown in Figure 5 is completed and "END" is reached, if the variable s has not reached the number of times that can be injected with a single ampoule, the injection control program returns to "START" in the flowchart and restarts the information processing flow.
On the other hand, when the variable s reaches the number of times that can be injected with a single ampoule, an initialization program that is part of the control program drives the second actuator (motor) 10 shown in Figure 1 in reverse rotation to move the piston rod 520 backward and return it to its initial position, and performs information processing to set the value of the variable s to 0.
By driving the needle-free syringe 1 through the above information processing, it becomes possible to repeatedly inject the injection liquid 301 in a single ampoule 3 in multiple doses.

1-3. Second Embodiment Figure 6 is a schematic diagram showing a needle-free injection system according to a second embodiment of the present invention.
As shown in FIG. 6, the needle-free injection system 1S of the second embodiment is a system made up of a combination of multiple devices such as a multi-step injector 1U, a control box 11B, and a foot switch 15, and parts that connect them.

1, the multi-step injector 1U has a piston, an elastic body (coil spring), an elastic body energy storage unit, a first actuator (motor), a piston head stop position adjustment unit, and a second actuator (motor) within the machine casing body, and an ampoule can be attached to the front of the machine casing body. However, the multi-step injector 1U does not have a control unit inside, and a control unit is provided inside a control box 11B, which is a separate device.
A cord 1103 connecting the control box 11B and the multi-step injector 1U supplies power to the multi-step injector 1U and enables electrical communication between the first and second actuators (motors) and various sensors inside the multi-step injector 1U and a control unit inside the control box 11B. Similar to the control unit of the needleless syringe of the first embodiment, the control unit inside the control box 11B controls the driving of the first and second actuators (motors) to operate the multi-step injector 1U, thereby enabling the injection liquid in a single ampule to be repeatedly injected in multiple divided doses.
A cord 1104 connecting the control box 11B and the foot switch 15 enables electrical communication between a control unit inside the control box 11B and the foot switch 15. In the needle-free syringe of the first embodiment, the injection liquid is automatically injected when the user presses the injection button, but in the needle-free injection system 1S of the second embodiment, the injection liquid is automatically injected from the multi-step injector 1U when the user steps on the foot switch 15. The multi-step injector 1U is heavy and needs to be lifted with both hands, but using the foot switch 15 makes the injection operation easier.

As shown in FIG. 6, the control box 11B is provided with a power switch 1105, and by switching this to ON, power can be supplied to the multi-step injector 1U and the control unit inside the control box 11B.
The control box 11B also includes a touch panel 1106, which displays various information required by the user and allows the user to perform operations via the touch panel 1106.
The touch panel 1106 displays the number of times that injection liquid can be injected from a single ampule as the “set number,” and the number of times that injection liquid has been injected after the ampule has been replaced as the “operation number.” This allows the user to grasp the number of injections that have been administered to patients and the number of times that can be injected from the same ampule.

6, the setting condition "0.4 ml 8 shots" is displayed in the upper left portion of the touch panel 1106. Here, "0.4 ml" indicates that the initial volume of injection liquid in the ampule is 0.4 ml, and "8 shots" indicates that the injection liquid in one ampule can be injected 8 times.
The setting conditions can be changed by the user pressing a "Settings" button in the lower left portion of touch panel 1106. When the user presses the "Settings" button, the screen of touch panel 1106 switches to a setting conditions selection screen (not shown), and the user can change the setting conditions by touching an option for the setting conditions displayed on the setting conditions selection screen.
If the initial value of the injection volume in the ampule is different, the initial position of the plunger that pushes out the injection volume in the ampule will also be different, and unless the position of the piston rod (piston head) is initialized to match this position, a "blank shot" may occur, in which the injection volume is not injected even when the injection operation is performed, and problems such as the injection volume leaking when the plunger is pressed by the piston head when the ampule is attached to the front end of the multi-step injector 1U may occur. Therefore, the control unit inside the control box 11B initializes the position of the piston rod (piston head) according to the initial value of the injection volume in the ampule set by the user.
In addition, the control unit inside the control box 11B adjusts the amount of injection liquid per injection by changing the distance by which the piston head stop position is moved forward after each injection, depending on the number of times the injection liquid can be injected as set by the user, thereby enabling the injection liquid to be injected the number of times set by the user.

As shown in FIG. 6, a vacuum attachment 1610 is attached to the front end of the multi-step injector 1U. One end of a suction tube 1621 is attached to the vacuum attachment 1610, and the other end of the suction tube 1621 is attached to an aspirator 1620. The aspirator 1620 is located on top of the control box 11B and is equipped with a vacuum pump inside. It can suck air from inside the vacuum attachment 1610 through the suction tube 1621 to create a negative pressure lower than atmospheric pressure. To generate negative pressure using the aspirator 1620, touch the "Suction" button displayed on the touch panel 1106 and turn it "ON," which will start suction using the vacuum pump of the aspirator 1620.

Figure 7 is a schematic diagram showing the cross-sectional structure of the front end of a multi-step injector with a vacuum attachment attached, and how to use it. Figure 7(A) shows the state before the skin is attached to the vacuum attachment, and Figure 7(B) shows the state after the skin is attached to the vacuum attachment.
7(A), the vacuum attachment 1610 has a cylindrical shape with two open ends, and the inner diameter of the rear open end is slightly larger than the outer diameter of the front end of the machine casing main body 2 of the multi-step injector 1U. This allows the rear open end of the vacuum attachment 1610 to be fitted into the front end of the machine casing main body 2 of the multi-step injector 1U and detachably attached. The ampoule 3 is attached to the front end of the machine casing main body 2, and a space is formed around the ampoule 3 by surrounding it with the vacuum attachment 1610.

Conventional attachments for needle-free syringes also have a similar shape, and by attaching them to the front end of the needle-free syringe and pressing the open end of the attachment firmly against the skin, loose skin can be made taut, making it easier to inject the injection solution subcutaneously. However, pressing the attachment too hard against the skin can cause pressure pain for the patient, which is a major problem, especially when injecting into the delicate facial area.

7A, the vacuum attachment 1610 used in the needle-free injection system 1S of the second embodiment has an attachment port to which a suction tube 1621 can be attached. The suction tube 1621 is connected to an aspirator 1620, and the air can be sucked in by a vacuum pump provided in the aspirator 1620, thereby reducing the pressure in the internal space surrounded by the vacuum attachment 1610.
As shown in Figure 7 (A), the surface of the skin 17 into which the injection liquid 301 is to be injected is in a loose state, and even if the injection liquid 301 is ejected at high speed toward the skin 17, the loose skin 17 absorbs the injection liquid 301 while significantly deforming, thereby absorbing the kinetic energy of the injection liquid 301, and it may not be possible to inject the injection liquid 301 subcutaneously.

7(B), by bringing the open end of vacuum attachment 1610, the interior of which has been decompressed, closer to the skin, skin 17 is adsorbed to the vacuum attachment, and skin 17 is further sucked into the decompressed interior of vacuum attachment 1610, thereby pulling loose skin 17 and making the surface of skin 17 tightly taut. Skin 17 with a tightly taut surface is less likely to deform and is therefore unable to absorb the kinetic energy of injection solution 301, and because skin 17 is pulled and stretched, the epidermis and dermis become thinner.
Therefore, when the plunger 304 is pressed by the piston head 522 to eject the injection liquid 301 at high speed, the injection liquid 301 can be injected subcutaneously and can be diffused subcutaneously.

As shown in Figure 7(B), the vacuum attachment 1610 has an air hole 1611. This air hole 1611 can be used to adjust the reduced pressure inside the vacuum attachment 1610. As shown in Figure 7(B), when the air hole 1611 is blocked with the finger 18, the pressure inside the vacuum attachment 1610 can be strongly reduced, and the skin 17 can be sucked into the vacuum attachment 1610. After the subcutaneous injection of the injection solution 301 is complete, the finger 18 can be removed from the air hole 1611 to ease the reduced pressure inside the vacuum attachment 1610 and release the skin 17 from being adsorbed to the vacuum attachment 1610.

In the second embodiment of the needle-free injection system 1S, the control unit is not located in the multi-step injector 1U shown in FIG. 6, but in the control box 11B, which is a separate device. The present invention is not limited to this embodiment, and the first actuator and/or second actuator may also be located in the control box 11B. In this case, the first actuator and/or second actuator may be a hydraulic actuator, a pneumatic actuator, or an actuator that transmits power via a wire, and a path for oil, air, or wire is provided in the cord 1103 to transmit the power generated by driving the actuator in the control box 11B to the elastic body energy storage unit and/or piston head stop position adjustment unit in the multi-step injector 1U. This configuration further reduces the weight of the multi-step injector 1U held by the user.

2. Method for Driving Needle-Free Syringe or Needle-Free Injection System The method for driving a needle-free syringe or needle-free injection system of the present invention is the driving method according to [9] to [13] described in [Summary of the Invention] above.
The driving method of the present invention involves driving a needle-free syringe or needle-free injection system that utilizes an elastic body such as a spring, and includes the steps of:
A) a step of energizing an elastic body by using an elastic body energizing unit that energizes an elastic body by moving a piston rearward and a first actuator that drives the elastic body energizing unit;
B) changing the piston head stop position to a position in the forward direction by using a piston head stop position adjustment unit that adjusts the piston head stop position where the piston head stops when the stored elastic body is released to drive the piston forward, and a second actuator that drives the piston head stop position adjustment unit;
C) The elastic body is released to drive the piston forward, causing the piston head of the piston to press the plunger, thereby injecting the injection liquid from the ampoule.
By driving the needle-free syringe or needle-free injection system in this manner, the plunger that pushes out the injection liquid in the ampule is gradually pressed forward by the piston head, making it possible to repeatedly inject the injection liquid in a single ampule in multiple doses.

In the driving method of the present invention, "repeated" means performing steps A) to C) multiple times until all of the injection liquid in the ampoule is injected. Therefore, steps A) to C) may be performed multiple times consecutively within a short period of time, or multiple injections may be performed with a long interval between each injection.
Details of the driving method of the present invention are as described in detail in the chapter " 1. Needle-free syringe or needle-free injection system " above, where the operation of each part of the needle-free syringe or needle-free injection system is explained in detail.

3. Control Program The control program of the present invention is the control program according to the above items [14] to [17] described in [Summary of the Invention].
The control program of the present invention is a program that causes a control unit included in the needle-free syringe or needle-free injection system of the present invention to execute specific information processing. The control program of the present invention may be stored in a storage device included in the needle-free syringe or needle-free injection system, and by reading out the control program, the specific information processing described in the control program may be executed by an information processing device included in the control unit. Furthermore, the control program of the present invention may be stored in a storage device of a server and downloaded to a mobile terminal or the like via the Internet, causing the mobile terminal or the like to function as the control unit of the needle-free injection system.
The control program of the present invention is not limited to this, but may be, for example, a program that includes as a part thereof an injection control program that executes information processing of the flow as shown in the above section " 1-2-6 . Control program" and in Fig. 5. Furthermore, as an example of the control program of the present invention explained in the section "1-2-6. Control program," in addition to the injection control program that controls the operation of injecting the injection liquid, the control program of the present invention may also include a program that realizes other functions, such as an injection count display program.

The needle-free syringe or needle-free injection system, as well as the drive method and control program for the needle-free syringe or needle-free injection system of the present invention, are inventions relating to medical, veterinary, or experimental equipment, as well as the drive method and control program for said equipment. They are not inventions relating to methods for treating or diagnosing humans, and are therefore inventions that can be used industrially.

1, 1A Needle-free syringe 1S Needle-free injection system 1U Multi-step injector 2 Machine frame body 201 Female screw 3, 3A Ampoule 301 Injection solution 302 Cylinder 303 Discharge nozzle 303A Discharge port 304, 304A Plunger 305 Male screw 306 Stopper 4 Piston syringe 5, 5A Piston 510 Piston base 511 Piston follower 512 Washer 513 Female screw 520 Piston rod 521 Male screw 522, 522A Piston head 523 Teeth 6 Elastic body (coil spring)
6A Spring
7 Elastic energy storage unit 710 Rod 720 Ball bearing 730 Gear 731 Teeth 740 Base 750 Cam 8 First actuator (motor)
810 Gear 811 Teeth 820 Shaft 9 Piston head stop position adjustment portion 910 Internal gear 911 Teeth 920 Ball bearing 10 Second actuator (motor)
11 Control unit 11B Control box 1101 Cable 1102 Cable 1103 Cord 1104 Cord 1105 Power switch 1106 Touch panel 1201 Injection button 1202 Injection liquid amount changeover switch 1210A Trigger 1211A Trigger finger 1212A Push end 1220A Safety lock 1301 Piston rod position sensor 1302 Piston base position sensor 14 Power cable 15 Foot switch 1610 Vacuum attachment 1611 Air hole 1620 Aspirator 1621 Suction tube 17 Skin 18 Finger

Claims (15)

A needleless syringe or needleless injection system comprising: a housing body to the front of which an ampoule having a plunger for pushing out an injection liquid therein; a piston provided on the housing body so as to be slidable back and forth; and an elastic body for applying a forward force to the piston, wherein the piston head of the piston presses the plunger by releasing the stored energy of the elastic body to drive the piston forward, thereby injecting the injection liquid in the ampoule,
an elastic body energy storing unit that stores energy in the elastic body by moving the piston rearward;
a first actuator that drives the elastic energy storage portion;
a piston head stop position adjustment unit that adjusts a piston head stop position where the piston head stops when the stored energy of the elastic body is released to drive the piston forward;
a second actuator that drives the piston head stop position adjustment unit;
a control unit that controls the first actuator and the second actuator,
the piston has a piston base to which a forward force is applied by the elastic body, and a piston rod having the piston head,
the piston rod is connected to the piston base so that it can receive a forward force from the piston base and can change its front-to-rear position relative to the piston base,
the piston head stop position adjustment unit can adjust the piston head stop position by changing the relative position of the piston rod with respect to the piston base back and forth using the driving force of the second actuator,
a needle-free syringe or needle-free injection system, characterized in that the control unit controls the driving of the first actuator and the second actuator, and repeatedly charges the elastic body by the elastic body charging unit, changes the piston head stop position in the forward direction by the piston head stop position adjustment unit, and drives the piston in the forward direction by releasing the elastic body. The device further has an interface for setting the number of injections per ampoule or the amount of injection liquid per injection;
2. The needle-free syringe or needle-free injection system according to claim 1, wherein the control unit controls the distance of forward displacement of the piston head stop position by controlling the drive amount of the second actuator according to the number of injections per ampoule or the amount of injection liquid per injection set by a user via the interface. The piston rod and the piston base are connected to each other by a male and female thread structure,
3. The needle-free syringe or needle-free injection system according to claim 1, wherein the piston head stop position adjustment unit changes the position of the piston rod relative to the piston base by rotating the piston rod and the piston base relative to each other using the driving force of the second actuator. a spur gear having a plurality of teeth extending linearly in the front-rear direction is formed on the outer periphery of a portion of the piston rod,
The piston head stop position adjustment unit has a cylindrical internal gear that is slidable back and forth relative to the spur gear and has a plurality of teeth on its inner circumference that extend linearly in the back and forth direction,
4. The needle-free syringe or needle-free injection system according to claim 3, wherein the rotational driving force of the second actuator can be transmitted to the spur gear via the internal gear to rotate the piston rod, regardless of the position of the piston rod sliding back and forth. the elastic energy storage unit has a cam that can convert the rotational movement of the first actuator into a forward and backward movement of the piston,
3. The needle-free syringe or needle-free injection system according to claim 1 or 2, wherein the cam is rotatable around an axis in the front-rear direction along which the piston slides, and the cam has a shape in which the thickness in the front-rear direction of the portion where it abuts against the piston changes with the rotation of the cam, thereby converting the rotational movement of the first actuator into movement in the front-rear direction of the piston to store energy in the elastic body. a portion in which the cam is shaped so that the thickness in the front-rear direction of the portion that abuts against the piston gradually increases as the cam rotates, thereby enabling the elastic body to store energy;
6. The needle-free syringe or needle-free injection system according to claim 5, further comprising a portion in which the thickness of the portion that comes into contact with the piston is formed into a stepped shape that rapidly decreases as the cam rotates, thereby enabling the elastic body to be released. 3. The needle-free syringe or needle-free injection system according to claim 1 or 2, further comprising a piston rod position sensor capable of detecting the position of the piston rod in the forward/backward direction and transmitting the detection result to a control unit, or a piston base position sensor capable of detecting the position of the piston base in the forward/backward direction and transmitting the detection result to a control unit. a vacuum attachment having a cylindrical shape with two open ends, one of which can be attached to the plunger or to the front of the machine body to which the plunger is attached, and the other of which can be brought into contact with the skin;
3. The needle-free syringe or needle-free injection system according to claim 1, further comprising an aspirator that can bring the skin into close contact with the attachment by sucking air from within the vacuum attachment. A method for driving a needleless syringe or a needleless injection system, comprising: a machine case main body to the front of which an ampoule having a plunger for pushing out an injection liquid therein; a piston provided on the machine case main body so as to be slidable back and forth; and an elastic body for applying a forward force to the piston, wherein the piston head of the piston presses the plunger by releasing the stored energy of the elastic body to drive the piston forward, thereby injecting the injection liquid in the ampoule,
A) a step of energizing the elastic body using an elastic body energizing unit that energizes the elastic body by moving the piston rearward and a first actuator that drives the elastic body energizing unit;
B) changing the piston head stop position to a position in the forward direction by using a piston head stop position adjustment unit that adjusts a piston head stop position where the piston head stops when the stored energy in the elastic body is released to drive the piston forward, and a second actuator that drives the piston head stop position adjustment unit;
C) releasing the elastic body to drive the piston forward, causing the piston head of the piston to press the plunger, thereby injecting the injection liquid from the ampoule. The method for driving a needle-free syringe or needle-free injection system according to claim 9, characterized in that in step B), the distance by which the piston head stop position is moved forward is controlled by controlling the drive amount of the second actuator in accordance with the number of injections of the injection liquid or the amount of injection liquid per injection set by the user. The method for driving a needle-free syringe or needle-free injection system according to claim 9, characterized in that step A) and step B) are performed simultaneously. The method for driving a needle-free syringe or needle-free injection system according to claim 9 or 11, characterized in that in step B), a piston rod position sensor is used to detect the position of the piston rod in the forward and backward directions, and when it is detected that the position of the piston rod has moved forward beyond a predetermined position, driving of the second actuator is stopped. The method for driving a needle-free syringe or needle-free injection system described in claim 9 or 11, characterized in that steps A) to C) are performed immediately before the injection of the injection liquid. A') generating a command signal to drive the first actuator by a predetermined amount in order to energize the elastic body in the control unit of the needle-free syringe or needle-free injection system according to claim 1;
B') generating a command signal to drive the second actuator a predetermined amount to change the piston head stop position to a forward position;
C') generating a command signal to release the stored energy of the elastic body in order to release the energy of the elastic body. 15. The control program according to claim 14, further comprising causing the control unit to execute information processing for specifying a predetermined amount for driving the second actuator in step B') based on the number of injections of the injection solution or the amount of injection solution per injection set by a user.