JP2009023251A - Inkjet recording device - Google Patents

Abstract

Disclosed is an off-carriage inkjet recording apparatus that reduces waste ink with a simple configuration, and that is small in size and has little deterioration in ink quality.
The apparatus includes a carriage 5 on which a recording head 4 is mounted, a main tank 1 installed in the apparatus main body, and a carriage 5 together with the recording head 4, and a liquid is placed between the main tank 1 and the recording head 4. Are temporarily stored, an air chamber 8 formed in the sub-tank 14, and a decompression pump 11 that is disposed in the apparatus main body and depressurizes the air chamber 8. The sub tank 14 is constituted by a tank case made of a flexible film on one side, and the pressure chamber 6 is formed inside the tank case. The tank case includes an air chamber 8 that communicates with the pressure chamber 6 through an opening, a gas-liquid separation film 7 disposed in the opening, and an urging force that urges the flexible film to the outside of the tank case. And a valve 3 that opens and closes the liquid inlet to the pressure chamber 6 in conjunction with the flexible film.
[Selection] Figure 1

Description

  The present invention relates to an ink jet recording apparatus that performs recording by discharging droplets.

  Ink jet recording apparatuses include a so-called serial type in which a recording head is reciprocally scanned in a predetermined direction with respect to a recording medium, and an image is formed by conveying the recording medium in a direction orthogonal thereto. The ink supply method applied to such an ink jet recording apparatus is referred to as an on-carriage method in which an ink tank is attached to a recording head mounted on a carriage or the like and reciprocally moved (main scanning) so as to be integrated or separable to supply ink There is something to be done.

  In recent years, an ink jet recording apparatus (hereinafter also referred to as a printer) is required to be miniaturized and has a strong demand for performance of recording high-quality images at high speed. In order to realize these, the carriage is required to move stably at high speed. For this purpose, it is advantageous that the carriage or the ink tank mounted thereon is small and light. However, if the ink tank is reduced in size and weight, the volume of ink held in the ink tank must be reduced, and the user is forced to frequently replace the ink tank.

  Therefore, recently, an in-tank is provided separately from the print head mounted on the carriage, and it is fixedly installed on a part other than the carriage, and an off-carriage method is adopted in which the ink tank and print head are connected to supply ink. The benefits of doing so have been reviewed. Among them, there is a recording head or carriage provided with a storage portion (hereinafter referred to as a sub tank) that temporarily stores a relatively small amount of ink, and ink is intermittently supplied to the sub tank from the ink tank at an appropriate timing. In particular, a pipe in which the sub tank of the recording head and the main tank fixed to the ink jet recording apparatus main body are in fluid communication at a predetermined position of the carriage does not require piping or the like for following the movement of the carriage. Therefore, it is advantageous for realizing a reduction in the size of the printer and a stable movement of the carriage.

  The sub-tank is required to maintain a negative pressure for properly supplying ink to the recording head and to have a substantial ink holding amount (net ink amount: Net) that can cover the ink flow rate consumed by the recording head. . However, if air enters into the sub tank due to gas permeation from the outside, fluid connection between the sub tank and main tank, ink tank installation, etc., the air expands due to a decrease in the net amount of ink in the sub tank or changes in the outside air temperature and pressure. Ink dripping occurs from the recording head. Therefore, it is necessary to estimate the amount of air mixed in the sub tank and provide an air buffer, and the sub tank is enlarged. Further, when the air in the sub tank reaches the recording head, it causes a printing failure, so that a lot of ink is wasted by performing the operation of removing the air.

  Patent Document 1 proposes an ink jet recording apparatus configured to supply ink from a main tank to a recording head via a buffer tank mounted on a carriage via an ink supply pipe. In this configuration, the negative pressure is generated by the water head difference between the recording head and the buffer tank, and the ink is supplied by the water head difference. The air mixed in the buffer tank is separated from the ink by the buffer tank and removed by sucking the air discharge passage. This reduces the amount of ink consumed when air is discharged.

  In Patent Document 2, an ink container provided on a carriage and capable of generating a negative pressure inside by a volume change, opening and closing of an air release valve provided in the ink container, and pressure-feeding ink from the main tank to the ink container A configuration having an ink replenishing device is disclosed. In this configuration, a negative pressure is generated by the ink container, the ink flow path is pressurized during ink supply, and the ink supply amount is controlled by using a liquid level detection sensor. By removing air while supplying ink, it is possible to remove air mixed in the ink container without increasing the amount of ink to be discarded.

  Patent Document 3 proposes a liquid ejecting apparatus configured such that a valve unit mounted on a carriage and having a self-sealing function receives liquid from a main tank. The valve unit includes a pressure chamber, a film member that displaces as the liquid in the pressure chamber decreases, and a movable valve that opens and closes the supply path in conjunction with the film member. In this configuration, the negative pressure is generated by the pressure chamber, the ink flow path is pressurized during ink supply, and the ink supply amount is automatically controlled by the movable valve.

  The operation of the movable valve will be described below. 10A and 10B are cross-sectional views of the valve unit. When there is sufficient ink in the pressure chamber 134, the movable valve 138 is closed as shown in FIG. As the ink in the pressure chamber 134 is consumed, the film member 122 is displaced. Eventually, as shown in FIG. 9B, the film member 122 and the movable valve 138 come into contact with each other, the movable valve 138 is released, and the ink flows into the pressure chamber 134. As the ink flows into the pressure chamber 134, the film member 122 is displaced. When a predetermined amount of ink flows into the pressure chamber 134, the film member 122 and the movable valve 138 are brought into a non-contact state. This makes it possible to automatically keep the ink in the valve unit constant. Air mixed in the sub tank is removed by deaeration ink. According to the above configuration, the reliability of liquid supply can be improved with a small size and low cost.

  Patent Document 4 proposes a printing system including a replaceable print cartridge on a carriage. According to this, the valve unit having a self-sealing function mounted on the carriage is configured to receive the liquid from the main tank. In this configuration, the negative pressure is generated by the valve unit, the ink flow path is pressurized when ink is supplied, and the ink supply amount is automatically controlled by the movable valve. Since the air generated in the print cartridge is accumulated in an air buffer provided in the print cartridge, it is not necessary to remove the air.

Patent Document 5 proposes a printing system in which a sub tank and a main tank are connected by two tubes, and ink supply and air bleeding are performed by circulating ink. In this configuration, negative pressure is generated by the sub-tank, and when supplying ink, first the ink in the sub-tank is returned to the main tank and the sub-tank is emptied, and then the ink flow path is pressurized to supply a certain amount of ink. Yes. The air generated in the sub tank can be removed without causing waste ink by circulating the ink.
JP 2004-255862 A JP 2003-237108 A Special Registration No. 03606282 Japanese Patent Laid-Open No. 10-128992 JP 2006-199040

  The background art described above has the following problems.

  In the invention described in Patent Document 1, it is necessary to discard the entire ink for air removal.

  In the invention described in Patent Document 2, it is necessary to press the film with a regulating member when ink is supplied. At that time, the ink supply path is in a pressurized state, which causes a problem of ink dripping from the recording head. Further, there is a need for a displacement detecting means comprising a displacement member for detecting a change in the volume of the ink container and a transmissive photosensor for detecting the displacement of the displacement member for replenishment detection, and a detection electrode for detecting the ink liquid level. Was complicated. In addition, since the ink level must be detected, the ink container becomes higher in the direction of gravity, and there is a concern that the pigment contained in the ink may settle and affect printing.

  In the invention described in Patent Document 3, when air is contained in the valve unit, there is a problem that the net amount of ink is reduced due to the movable valve closing when the ink in the valve unit is not sufficient. Furthermore, there is a problem that the internal pressure in the valve unit changes due to a change in the environmental temperature, causing ink leakage from the nozzles. A buffer was needed to solve these problems. The air that cannot be absorbed by the deaerated ink needs to be vented, and when the air is vented, the recording head needs to be discharged together with the ink by cleaning.

  In the invention described in Patent Document 4, since air generated in the ink flow path is accumulated in an air buffer provided in the print cartridge, the air buffer needs to have a capacity for storing air for the lifetime of the print cartridge. For this reason, the carriage has become larger.

  In the invention described in Patent Document 5, two valves are required for each color, and a control device for controlling each valve is required. Also, an air / ink sensor is required to supply an appropriate amount of ink to the sub tank. The device was complicated. In addition, since the ink must be reciprocated between the main tank and the sub tank, it takes a long maintenance time, and the ink stays in contact with the air, so the ink density changes due to evaporation, which may affect the print quality. was there.

  As described above, in order to supply ink to the sub-tank in the off-carriage system and perform air bleeding without waste ink, the ink quality is reduced, and the apparatus is increased in size and complexity.

  An object of the present invention is to eliminate at least one of the problems of the background art.

To achieve the above object, the present invention comprises a carriage on which a recording head is mounted,
A main tank installed in the recording apparatus main body, a sub tank mounted on the carriage together with the recording head, temporarily storing liquid between the main tank and the recording head, and generating a negative pressure against the recording head; A pressure reducing mechanism that is disposed in the apparatus main body and depressurizes the inside of the sub-tank to remove air in the sub-tank,
The sub tank is
A tank case at least partially made of a flexible film;
An opening formed in the tank case;
An air chamber communicating with the inside of the tank case through the opening;
A gas-liquid separation member that is disposed in the opening and allows passage of air but restricts passage of liquid;
A biasing member that biases the flexible film outward of the tank case;
A valve that opens and closes the liquid inlet into the tank case in conjunction with the movement of the flexible film;
It is characterized by having.

  According to the present invention, it is possible to reduce the air buffer in the sub tank, and it is possible to realize an off-carriage ink jet recording apparatus that reduces waste ink with a simple configuration, and that is small in size and has little deterioration in ink quality.

  Embodiments of the present invention will be described below with reference to the drawings.

"Example"
FIG. 1 shows a basic configuration of an ink supply system when the present invention is implemented. The main tank 1 is disposed in the printer main body other than the carriage 5, and is connected to a pressure chamber 6 inside a sub tank 14, which will be described later, via a tube constituting the ink supply path 2. The sub tank 14 is disposed in the sub tank box 13. The ink in the main tank 1 is supplied to the ink jet recording head 4 mounted on the carriage 5 through the pressure chamber 6. An ink valve 3 is provided at a connection portion of the pressure chamber 8 with the ink supply path 2.

  A decompression pump 11 that is a decompression mechanism used for venting the sub tank 14 is disposed in the printer main body, and an air chamber 8 provided in the sub tank 14 described later via a tube constituting the air flow path 10. It is connected to the. An air valve 9 that opens and closes the air flow path 10 is provided between the air chamber 8 and the decompression pump 11. The decompression pump 11 may also serve as a pump that performs suction recovery of the recording head 4.

  FIG. 2 shows the inside of the carriage 5 and the sub tank box 13 of the ink jet recording apparatus adopting the ink supply system shown in FIG. The carriage 5 includes a sub tank box 13 in which a plurality of sub tanks 14 are disposed, and a recording head 4. Further, the carriage 5 is supported so as to be movable along a shaft 12 fixed to the printer body. The moving direction of the carriage 5 is a direction that intersects the direction in which the recording sheet that faces the ink droplet discharge portion of the recording head 4 is conveyed.

  In the sub-tank box 13, sub-tanks 14 are stored and arranged at least as many as the number of colors of the recording head 4 (four in FIG. 2B). Moreover, each sub tank 14 is arrange | positioned so that the surface in which the flexible film 15 is provided may become a gravity direction downward. That is, the surface with the largest area of the tank case constituting the sub tank 14 is disposed substantially perpendicular to the direction of gravity. The sub tank box 13 has a communication hole for communicating the inside with outside air.

  3A, 3B, and 3C are perspective views of the sub tank 14 when the present invention is implemented.

  As shown in FIG. 3A, one surface of the outer shell of the sub-tank 14 is formed of a molded flexible film 15 and constitutes a part of the pressure chamber 6 described in detail later. The shape of the flexible film 15 may be an oval shape as shown in FIG. An ink introduction port (liquid introduction port) 17 and an ink supply port 16 are formed in the outer shell (sub tank case 22) of the sub tank 14 and communicate with the pressure chamber 6. The ink flowing from the main tank 1 through the ink supply path 2 enters the pressure chamber 6 from the ink introduction port 17 and is supplied from the ink supply port 16 to the recording head 4.

  FIG. 3B is a view showing the sub tank 14 with the flexible film removed. A negative pressure spring 19 and a pressure plate 21 are disposed in the pressure chamber 6 of the sub tank 14. The negative pressure spring (biasing member) 19 urges the flexible film 15 to the outside via the pressure plate 21 to generate a negative pressure in the pressure chamber 6.

  An ink valve 18 and a valve spring 20 are further arranged in the pressure chamber 6. The ink valve 18 is urged against the wall surface of the pressure chamber 6 by a valve spring 20 to close the ink introduction port 17. The ink valve 18 corresponds to the ink valve 3 schematically shown in FIG.

  FIG. 5 is a perspective view of the ink valve. The ink valve 18 includes an elastic member 28 for closing the ink introduction port 17 and a lever portion 29 for moving the elastic member 28. The elastic member 28 is an elastic member such as an elastomer, and is disposed corresponding to a portion of the wall surface in the pressure chamber 6 where the ink introduction port 17 is formed. The elastic member 28 is urged against the wall surface in the pressure chamber 6 by the valve spring 20 to close the ink introduction port 17. The lever portion 29 is provided in the pressure chamber 6 so as to be rotatable about the rotation shaft 27, and the elastic member 28 moves so as to open and close the ink introduction port 17 in conjunction with the rotation of the lever portion 29.

  FIG. 3C is a view showing a sub tank case 22 which is an outer shell of the sub tank 14. The inside of the sub tank case 22 corresponds to the pressure chamber 6 shown in FIG. 1, and an opening 23 is formed on at least one surface of the sub tank case 22. A gas-liquid separation membrane (gas-liquid separation member) 7 is disposed in the opening 23. One side of the sub tank case 22 is a ceiling of the pressure chamber 6, and an opening 23 is formed on the ceiling (top) in order to efficiently collect the air in the pressure chamber 6 in the gas-liquid separation film 7. An inclined structure 24 is provided.

  Furthermore, the inclined structure 24 includes a groove 26 that extends from one or more corners 25 in the opening 23 to the outside of the opening 23. Thereby, when the air approaches the opening 23, the ink in the opening 23 flows out along the groove 26, and it becomes easy to bring the air closer to the gas-liquid separation film 7.

  Next, the movement of the ink valve 18 will be described with reference to FIGS. 6 (a), 6 (b) and 6 (c).

  Hereinafter, the surface of the sub tank 14 on which the flexible film 15 is provided is referred to as the sub tank lower surface, and the surface opposite to the surface on which the flexible film 15 is provided is referred to as the sub tank upper surface.

  FIG. 6A is a bottom view of the sub tank corresponding to FIG. FIGS. 6B and 6C are views showing states when the ink valve is released and closed in the AA cross section of FIG. 6A. In order to make the movement of the ink valve 18 easy to see, these drawings in which the flexible film 15 is not shown are used.

  In the state of FIG. 6B, the ink in the pressure chamber 6 is sufficient, and the lever portion 29 and the pressure plate 21 are in non-contact state or in contact with each other, so that almost no force is applied to the lever portion 27. The introduction port 17 is closed.

  When the ink in the pressure chamber 6 decreases, the flexible film 15 is crushed and the lever portion 29 of the ink valve 18 is pushed through the pressure plate 21. When the lever portion 29 is pushed, it rotates about the rotation shaft 27 (FIG. 5), and the ink inlet 17 is opened as shown in FIG. 6 (b). Since the ink introduction port 17 is connected to the main tank 1 (FIG. 1), the ink flows into the pressure chamber 6 due to the negative pressure in the pressure chamber 6, and the flexible film 15 swells. As the flexible film 15 swells outward from the sub tank case, the lever portion 29 rotates, and the ink inlet 17 is closed when a predetermined amount is supplied. Note that the spring constants of the negative pressure spring 19 and the valve spring 20 are set so that such an operation is possible.

  Next, air venting in the sub tank 14 will be described with reference to FIGS. 7 (a), (b) and (c).

  7A, 7B, and 7C are perspective views of the upper surface of the sub tank.

  As shown in FIG. 7C, a concave groove 321 serving as an air chamber 32 is formed on one surface of the sub tank case 22 in which the opening 23 is formed. The gas-liquid separation membrane 7 is disposed in the opening 23 as shown in FIG. Then, as shown in FIG. 7A, the air chamber 32 is formed by adhering the channel film 30 to one surface of the sub tank case 22 and sealing the groove 321. The air chamber 32 is connected to the pressure chamber 6 in the sub tank case 22 through the gas-liquid separation membrane 7. By using the gas-liquid separation membrane 7, only air is allowed to pass from the pressure chamber 6 to the air chamber 30, and the passage of ink is restricted. The air chamber 32 corresponds to the air chamber 8 shown in FIG.

  The air chamber 32 is connected to the decompression pump 11 from the air discharge port 31 through a tube forming the air flow path 10 (see FIG. 1). An air valve 9 is provided between the air chamber 32 and the decompression pump 11, and the air valve 9 is closed except when performing air bleeding. When performing air bleeding, the air valve 9 is opened, and the air chamber 32 and the decompression pump 11 communicate with each other. Then, the air chamber 32 is decompressed by the decompression pump 11 so that the air in the pressure chamber 6 is removed. After air bleeding, the air valve 9 is closed.

  By such air venting using the gas-liquid separation membrane 7, it is possible to discard only air without discarding ink. Since waste ink does not occur due to air bleeding, it is possible to perform air bleeding frequently, and it is possible to reduce the air buffer volume of the sub tank and reduce the size of the sub tank.

  With the above configuration, an off-carriage ink jet recording apparatus can be realized with a simple configuration that is small and does not generate waste ink when bubbles are removed.

  The ink supply path 2 is not limited to a flexible tube. For example, the carriage 5 and the printer main body may each have a joint mechanism, and the flow path connection may be intermittent instead of the constant connection. Further, not only the ink supply path 2 but also the air flow path 10 may have a joint mechanism and intermittently connect the flow paths.

  Further, in order to increase the ink supply speed to the sub tank 14, it is desirable to have an ink supply speed acceleration mechanism. This is because it is effective when a large amount of ink in the pressure chamber 6 is consumed at once by the recording head 5 for solid printing or the like.

  An example of the ink supply speed promotion mechanism described above will be described below with reference to the drawings.

  As shown in FIG. 8, the sub tank box 13 is formed in an airtight state, and a supply decompression pump (second decompression mechanism) 34 is installed in the printer main body, and the interior of the sub tank box 13 and the supply decompression pump 34 are connected. Connect by tube 33. Then, the ink supply speed from the main tank 1 to the pressure chamber 6 can be increased by reducing the pressure inside the sub tank box 13 to a pressure lower than the internal pressure of the pressure chamber 6 by the supply decompression pump 34. The supply decompression pump 34 may serve as at least one of the decompression pump 11 and a pump that performs suction recovery of the recording head 4.

  Instead of the above-described type in which the sub tank side is depressurized to increase the ink supply speed, a type in which the main tank side is pressurized with air as shown in FIG. 9 may be used. In FIG. 9, the main tank includes an ink pack 38 made of a flexible material enclosing ink, and an outer case 36 formed in an airtight state around the ink pack 38 via a space 35. The The space 35 formed between the ink pack 38 and the outer case 36 is pressurized by the supply pressure pump 39, whereby the inside of the ink pack 38 is pressurized, and the ink supply speed to the pressure chamber 6 is increased. Can be raised.

  Although the present invention has been described with reference to the embodiments, it is needless to say that the present invention is not limited to the illustrated embodiments and can be appropriately modified without departing from the spirit of the present invention.

1 is a schematic diagram illustrating a basic configuration of an ink supply system of the present invention. (A) And (b) is a perspective view of the carriage in the Example of this invention, (c) is the figure which showed the inside of the sub tank box mounted in the carriage. (A) is a perspective view of the sub tank of FIG. 2 (b), and (b) and (c) are perspective views showing the internal structure of the sub tank. It is a perspective view which shows another example of a shape of the subtank of FIG.2 (b). It is a perspective view which shows the component of the ink valve of FIG.3 (b). (A), (b) and (c) is explanatory drawing for demonstrating a motion of an ink valve. (A), (b) and (c) is a perspective view for demonstrating the structure of an air chamber. It is the model which showed the basic composition of the ink supply system which performs pressure reduction supply. It is the model which showed the basic composition of the ink supply system which performs pressure supply. (A) And (b) is sectional drawing which shows the subtank (valve unit) mounted in the carriage of the printer which concerns on background art.

Explanation of symbols

1 Main tank 3, 18 Ink valve (valve)
4 Recording head 5 Carriage 7 Gas-liquid separation membrane (gas-liquid separation member)
8 Air chamber 11 Pressure reduction pump (pressure reduction mechanism)
14 Sub tank 15 Flexible film 17 Ink introduction port (liquid introduction port)
19 Negative pressure spring (biasing member)
22 Sub tank case (tank case)
23 opening

Claims (10)

A carriage for mounting the recording head;
A main tank installed in the recording device body;
A sub tank that is mounted on the carriage together with the recording head, temporarily stores liquid between the main tank and the recording head, and generates a negative pressure against the recording head;
A decompression mechanism that is disposed in the recording apparatus main body and depressurizes the sub-tank to remove air in the sub-tank;
An ink jet recording apparatus comprising:
The sub tank is
A tank case at least partially made of a flexible film;
An opening formed in the tank case;
An air chamber communicating with the inside of the tank case through the opening;
A gas-liquid separation member that is disposed in the opening and allows passage of air but restricts passage of liquid;
A biasing member that biases the flexible film outward of the tank case;
A valve that opens and closes the liquid inlet into the tank case in conjunction with the movement of the flexible film;
An ink jet recording apparatus.   2. The ink jet recording apparatus according to claim 1, wherein a surface of the tank case constituting the sub tank having the widest area is disposed substantially perpendicular to the direction of gravity.   The inkjet recording apparatus according to claim 1, wherein the gas-liquid separation member is provided on an upper surface of the tank case.   4. The ink jet recording apparatus according to claim 1, wherein an inclined structure having the opening as a vertex is provided inside the tank case.   The inkjet recording apparatus according to claim 4, wherein the opening has at least one corner, and a groove connected to the corner is provided inside the tank case.   The ink jet recording apparatus according to claim 1, wherein the pressure reducing mechanism also serves as a pump that performs suction recovery of the recording head.   7. The ink jet recording apparatus according to claim 1, wherein the carriage includes a sub tank box that houses a plurality of the sub tanks and has a communication hole that communicates the inside with outside air.   The inkjet recording apparatus according to claim 7, further comprising a second pressure reducing mechanism for reducing the pressure in the sub tank box.   9. The ink jet recording apparatus according to claim 8, wherein the second decompression mechanism serves as at least one of the decompression mechanism and a pump that performs suction recovery of the recording head.   The ink jet recording apparatus according to claim 1, further comprising a pressurizing unit that pressurizes the main tank.

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