JP2000117999A - Recorder and recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide nozzleless recorder and recording method in which high speed recording can be effected through a relatively simple structure while eliminating the effect of mutual interference of waves propagating on the liquid surface and residual oscillation at a recording section after recording. SOLUTION: An ink chamber 3 communicates with an ink layer 1 having an ink free surface 1a through an aperture 2. A liquid column forming piezoelectric element 4 and a recording piezoelectric element 5 are disposed in the ink chamber 3. A stabilized liquid column 1b is formed by starting and stopping driving of the liquid column forming piezoelectric element 4 repeatedly (B). When an external force is applied under that state, top of the liquid column 1b is constricted (C) and an ink drop flies (D) to adhere an image recording medium thus effecting recording.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording method in which a liquid column for maintaining a constant height is formed on a free surface of a liquid, and the liquid in the liquid column is moved to and adhered to an image recording medium to perform recording. The present invention relates to an apparatus and a recording method.

[0002]

2. Description of the Related Art Heretofore, an apparatus for recording an image by forming dots by making ink into droplets and flying on an image recording medium has been practically used as an ink jet printer. A general inkjet recording apparatus has a problem that clogging occurs because ink droplets fly from fine nozzles corresponding to the resolution. For example, in the case where a pressure generated by a bubble using a heating element is used, clogging occurs due to the insoluble matter due to a thermal or chemical reaction with ink adhering to the inner wall of the nozzle. When the pressure by the piezoelectric element is used, there is a problem that clogging occurs due to a complicated structure such as an ink flow path.
Usually, various measures are taken to prevent clogging. However, in a line scanning type head in which nozzles are arranged in the main scanning direction, the frequency of clogging becomes extremely high, and the reliability of the ink jet apparatus is significantly reduced. . Further, when high resolution is required to record a high-definition image, it is necessary to process the nozzle diameter to a small diameter of several tens μm. When thousands of nozzles are required as in the case of a line type head, a technique for processing this recording head is required, and it is extremely difficult in manufacturing to increase the resolution with the line type head.

[0003] In order to overcome these problems, an apparatus that uses an ultrasonic beam to eject ink droplets from the ink liquid surface has been proposed as a method that does not require a nozzle.
No. 943, JP-A-63-162253, JP-A-63-166545, and JP-A-8-238764.
JP, JP-A-8-290587, JP-A-9-3
No. 9224, JP-A-9-94957, JP-A-2-175157, JP-A-2-55139, JP-A-2-103152, JP-A-2-164
546 and JP-A-7-276622. Since all of these systems have a nozzleless configuration, the above-described problems such as clogging are unlikely to occur.

[0004] Such a nozzleless type ink jet printer can easily arrange the printing sections in the main scanning direction as compared with a nozzle type ink jet printer, and is effective for high speed printing. However, since the nozzles are nozzleless, there is a new problem that mutual interference between adjacent printing units occurs largely. For example, the vibration of the ink liquid surface that occurs after printing propagates to other printing units,
This hinders the flight of the ink droplets, causing the ejection direction to become unstable, and also causes obstacles such as the occurrence of idle hits in which the ink droplets do not fly.

As a configuration for preventing mutual interference, for example, there is JP-A-6-238884. In the printing method described in this publication, a porous cover having a large diameter is attached to each free surface on the ink free surface, the free surface area is partitioned by the large diameter portion of the printing portion, and waves propagating to other printing portions are separated. Preventing. However, the ink wave blocked by the cover is reflected by the cover and returns to the original printing section. Therefore, although mutual interference with other printing units can be prevented, the wave reflected by the cover has the same adverse effect as the mutual interference.

Normally, printing is performed until the influence of the above-described obstacle is substantially eliminated. This is disadvantageous for high-speed printing, and degrades the performance as a recording device. In addition, partitioning with a cover or the like has a disadvantage in supplying ink to the printing unit because the contact resistance between the ink and the supply path is increased, so that ink is supplied at high speed.

[0007] In addition to the waves propagating to the surroundings, there are residual vibrations remaining in the printing portion after printing, in addition to the waves propagating around the ink surface. Mutual interference due to propagating waves is a problem unique to the nozzleless system, but residual vibration also exists in a nozzle type ink jet recording apparatus. If you try to print again while the residual vibration is occurring,
As in the case of mutual interference, it hinders the flight of the ink droplets, causing the ejection direction to become unstable and the occurrence of idle hits in which the ink droplets do not fly.

One example of a system for reducing the influence of residual vibration is disclosed in JP-A-9-226106 and JP-A-2-506.
JP-A-5-338150, JP-A-10-338150
24570 and the like. For example, JP-A-9
In the method described in Japanese Patent No. 226106, erroneous ejection caused by the influence of residual vibration is prevented by setting parameters of a driving waveform so that vibration of the liquid surface is minimized. However, since this is not a method for suppressing residual vibration, the effect of reducing the effect of residual vibration is limited. Further, the methods described in JP-A-2-506 and JP-A-5-338150 disclose a method in which a sub-pulse is applied after application of a driving pulse for ejecting ink so as to cancel a reflected pressure wave which causes residual vibration. (Additional pulse) is applied. However, in these methods, it is important to control the timing of the drive pulse with high accuracy, and furthermore, the pulse timing for effectively canceling the reflected pressure wave is fixed because it changes depending on ink physical properties, environmental temperature, etc. At the timing, the residual vibration cannot be effectively suppressed. In the method described in Japanese Patent Application Laid-Open No. H10-24570, a drive pulse control means for controlling the pulse timing according to the environmental temperature is installed. In this method, too, there is a technique for controlling the timing of the drive pulse with high accuracy. This is necessary and is difficult to achieve with a small, inexpensive desktop inkjet printer. Also,
In any of the above-described methods, a nozzle-type printing apparatus is premised, so that it is difficult to apply the present invention to a nozzle-free printing apparatus.

The nozzleless ink jet recording apparatus capable of high-speed printing has the above-mentioned major problems. These are summarized in the following two points. (1) Fluctuations in the flying direction of ink droplets due to the influence of waves propagating on the ink surface after printing and blank hitting. (2) Fluctuations in the flying direction of ink droplets due to the influence of residual vibration remaining in the printing portion after printing, and blank hitting. The problem (1) does not exist in the nozzle type ink jet recording apparatus, and is a problem peculiar to the nozzleless system. (2)
The problem described above also exists in the nozzle type ink jet recording apparatus.
Attempts are being made to solve the problem by using a control technique such as that disclosed in Japanese Patent Publication No. 50.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a relatively simple structure.
Mutual interference by waves propagating on the liquid surface as described above,
Further, it is to solve various problems due to residual vibration remaining in the recording section after recording. By solving these problems, a recording apparatus and a recording method capable of adopting a nozzleless method that is advantageous for high-speed printing and achieving high-speed recording that could not be performed by the conventional nozzleless method due to vibration of the ink liquid surface. It is intended to provide.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a recording apparatus for performing recording by moving a liquid from a free surface of the liquid and attaching the liquid to an image recording medium at a position facing the free surface of the liquid. A liquid layer forming a free surface of the liquid layer, a liquid chamber communicating with the liquid layer via an aperture,
A volume changing element provided in the liquid chamber and capable of changing the volume in the liquid chamber; and driving the volume changing element to change the volume of the liquid chamber to move toward the free surface of the liquid via the aperture. It is characterized by having driving means for forming a liquid column having a certain height on the free surface of the liquid by repeatedly generating the generated ink flow, and moving means for moving the liquid from the liquid column to the image recording medium. is there.

In a recording method for performing recording by moving a liquid from a free surface of a liquid and attaching the liquid to an image recording medium at a position facing the free surface of the liquid, a liquid layer forming a free surface of the liquid is provided. And a liquid chamber communicating with the liquid layer via an aperture, and by changing the volume of the liquid chamber to repeatedly generate an ink flow generated toward the free surface of the liquid through the aperture, thereby forming a liquid. A liquid column having a certain height is formed on the free surface of the recording medium, and recording is performed by moving the liquid from the liquid column to the image recording medium.

As the volume changing element forming the liquid column, for example, a piezoelectric element can be used, and a volume change in the liquid chamber caused by driving the piezoelectric element is used to form a bulge as a liquid column on the free surface of the liquid. Can be formed.
Since the liquid column is always obtained by driving the volume changing element, even if the physical property of the liquid changes due to an environmental change, the liquid column is hardly affected. Therefore, in comparison with the conventional method in which the sub-pulse is provided with the counter effect of the residual vibration, the present invention does not require the management of the change in the physical properties of the liquid caused by the environmental change and the high-precision timing control, and enables stable recording. .

The liquid can be arbitrarily moved to the image recording medium by applying some external force to the formed liquid column. As a moving means for moving the liquid droplet to the image recording medium, various means such as changing the volume of the liquid chamber by a piezoelectric element, generating a bubble by a heat generating mechanism, or using an electrostatic attraction force are used. Can be. Further, the same piezoelectric element as the volume changing element may be used.

Further, when the liquid in the liquid column is moved to the image recording medium, the liquid in the liquid column can be formed into droplets, fly, adhere to the image recording medium, and perform recording. Of course, the liquid may be moved in such a manner that the tip of the liquid column is attached to the image recording medium in a string form.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 3 are explanatory views of the principle configuration of the present invention. In the figure, 1 is an ink layer, 1a is an ink free surface, 1b is a liquid column, 1c is a concave portion, 2 is an aperture, 3 is an ink chamber, 4 is a liquid column forming piezoelectric element, and 5 is a recording piezoelectric element. In this example, ink is used as a liquid that is attached to an image recording medium (not shown) to form an image. The liquid column forming piezoelectric element 4 is used as the volume changing element, and the recording piezoelectric element 5 is used as the moving means. Although the drive means for driving the volume changing element is not shown here, it is assumed that electric energy is supplied to the liquid column forming piezoelectric element 4. Also, the recording piezoelectric element 5
Are not shown in the figure.

As shown in FIG. 1 (A), an ink chamber 3 is provided on an ink layer 1 on which an ink free surface 1a is formed. The ink chamber 3 is provided with a liquid column forming piezoelectric element 4 and a recording piezoelectric element 5.

When, for example, a piezoelectric element 4 for forming a liquid column provided in the ink chamber 3 is driven, the ink chamber 3 is compressed and the ink in the ink chamber 3 passes through the aperture 2 as shown in FIG. , Flowing toward the free ink surface 1a. Due to this flow of ink, a liquid column 1b is formed on the free ink surface 1a as shown in FIG. Then, liquid column 1
b is crushed by its own weight and surface tension, and returns to the original ink free surface 1a.

As shown in FIG. 1D, after the ink free surface 1a is flattened while the liquid column forming piezoelectric element 4 is driven, the driving of the liquid column forming piezoelectric element 4 is stopped. Then, as shown in FIG. 1E, ink flows from the ink layer 1 forming the ink free surface 1b through the aperture 2 to the ink chamber 3. Then, as shown in FIG. 1F, a concave portion 1c is formed on the ink free surface 1a.

When the driving of the above-described liquid column forming piezoelectric element 4 is started, the ink passing through the aperture 2 flows toward the ink free surface 1a with inertia. Further, the ink flow when the driving of the liquid column forming piezoelectric element 4 is stopped is as follows.
Unlike when the driving of the liquid column forming piezoelectric element 4 is started,
As shown in FIG. 1E, the ink flows into the ink chamber 3 from the entire area including the area above and around the aperture 2.

As described above, when the ink flows from the aperture 2 toward the free ink surface 1a, the ink passing through the aperture 2 flows toward the free surface with inertia and forms a liquid column in a narrow area. When the ink is drawn into the ink chamber 3, the ink is drawn from a wide area on the ink layer 1 side to form a depression (recess).

Next, as shown in FIG. 2A, the piezoelectric element 4 for forming a liquid column is driven, and the driving is immediately stopped. When such driving is performed, the phenomenon is different between when the driving of the liquid column forming piezoelectric element 4 is started and when the driving is stopped, as described above. 2 and the phenomena shown in FIGS. 1D to 1F simultaneously occur, and FIG.
As shown in (B), a liquid column 1b is formed on the ink free surface 1a, and a recess 1c is formed around the liquid column 1b.
Thereafter, due to the surface tension acting on the free ink surface 1a, the liquid column 1b and the concave portion 1c gradually become smaller as shown in FIGS. 2C and 2D, and after a while, as shown in FIG.
Return to the flat liquid level as shown in FIG.

FIG. 3 shows a case where the driving of the liquid column forming piezoelectric element 4 is started and stopped not only once as shown in FIG. 2 but also repeatedly. In this case, FIG.
The liquid column 1b is formed as shown in FIG. 3B by starting and stopping the driving of the liquid column forming piezoelectric element 4 from the state where the ink free surface 1a is flat as shown in FIG. By starting and stopping the driving of the liquid column forming piezoelectric element 4 again before the ink free surface 1a becomes flat, the liquid column 1b is always formed. At this time, the liquid column 1b grows in each period of the driving start and the driving stop of the liquid column forming piezoelectric element 4. Therefore, the liquid column 1b does not become infinitely high, but actually settles at a height that balances the surface tension.

The time from when the liquid column forming piezoelectric element 4 is driven once and when the driving is stopped to when the liquid surface rises and the liquid column 1b is formed and returns to a flat state, and then the liquid column forming piezoelectric element 4 If the repetition interval before driving is short, FIG.
As shown in (C), the liquid column 1b
Are formed continuously. By continuously driving the liquid column forming piezoelectric elements 4 at shorter intervals, FIG.
As shown in (D) to (F), the vibration of the liquid column 1b is almost eliminated, and a constant height can be maintained. In order to form the liquid column 1b without vibration as described above, a repetition interval of 50 kHz or more is desirable, and more preferably, a repetition interval of 100 kHz or more is more desirable.

FIG. 4 is an explanatory diagram of the process of flying ink droplets. As described above, a stable liquid column 1b could be formed on the flat ink free surface 1a as shown in FIG. 4A, as shown in FIG. 4B. Some external force is applied to the liquid column 1b in this state. For example, the recording piezoelectric element 5 is driven to move the ink in the ink chamber 3 through the aperture 2. The force at this time can further push up the top of the liquid column 1b as shown in FIG. When the external force stops, the vicinity of the top of the liquid column 1b rises as it is due to the inertial force, but the lower portion of the liquid column 1b returns to the original liquid column 1b due to its own weight and surface tension.
The top of the pushed liquid column 1b is narrowed. Further, the vicinity of the upper portion of the liquid column 1b continues to move due to the inertial force, and the constricted portion is cut off as shown in FIG. Then, as shown in FIG. 4E, the ink droplet flies as it is due to the inertial force, and the liquid column 1b returns to its original stable shape.

The external force applied to the liquid column 1b is not limited to the above-described recording piezoelectric element, but may be generated by various means such as generating bubbles by a heat generating mechanism or using electrostatic attraction. Can be used. Further, a larger electric energy may be applied to the liquid column forming piezoelectric element 4.

The external force for causing the ink droplets to fly may be smaller than when the ink droplets are caused to fly from a state where the ink liquid level is flat as shown in FIG. That is, the external force is smaller when the ink droplet is formed in the state where the liquid column 1b is formed in advance as in the present invention than when the liquid column 1b is formed and the external force that causes the ink droplet to fly from the state where the liquid column 1b is not formed. May be. If the liquid column is formed in advance, for example, the ink droplet can be made to fly with about one-third of the energy (force) when the ink droplet is made to fly from a flat liquid surface.

FIG. 5 is a graph showing an example of the relationship between the energy of the external force and the vibration amplitude and vibration time of the liquid surface. FIG.
As shown in (A), the larger the energy of the external force applied when the ink droplet flies, the larger the vibration amplitude of the liquid surface after the ink droplet flies. Similarly, FIG.
As shown in (B), the greater the energy of the external force applied when the ink droplet flies, the longer the time required for the vibration of the liquid surface to converge after the ink droplet flies. As described above, by forming the liquid column in advance, the energy of the external force required to cause the ink droplet to fly can be reduced to about の of the energy required to cause the ink droplet to fly from a flat liquid surface. Degree is fine. As shown in FIG. 5 (A),
As shown in (B), the vibration amplitude and the vibration time after the ink droplet is caused to fly are also reduced to about 1/2 to 1/3. Therefore, the waiting time from the time when the ink droplet flies to the time when the next ink droplet flies can be significantly reduced. For this reason, it is possible to perform printing at a higher speed than before, without having to worry about ejection instability due to residual vibration or mutual interference after printing.

Further, in the conventional nozzleless system, the vibration generated on the ink free surface 1a after the ink droplet is caused to fly is large, and this vibration has a great influence on the next recording and the adjacent printing portion. On the other hand, in the present invention, since the liquid column 1b is formed by the flow of the ink, the vibration generated on the free surface of the ink after the ink droplet flies is small, and propagates from another printing portion. The vibration wave is a wave having a lower height than the liquid column which is always formed. Therefore, even though the liquid column may be slightly shaken by the propagating wave, the liquid column top portion is maintained at a considerably stable state, and the influence is small. Therefore, compared with the effect of the vibration wave that propagates the ink free surface without the liquid column, the present invention
The effect of the vibration wave is sufficiently small.

For example, assuming that recording is performed at a resolution of 600 dpi or more, as shown in FIG.
An ink droplet having a diameter of about 0 μm is caused to fly.
In this case, in order to form the liquid column 1b without vibration, it is desirable that the frequency be 50 kHz or more, more desirably, 10 kHz as described above.
It is preferable to perform the process at a repetition interval of 0 kHz or more. When flying fine droplets, the amount of ink moved as a fluid may be smaller than when flying large droplets, but the frequency at which the ink liquid surface oscillates must be high. In general, the natural frequency for a moving mass m changes by √ (1 / m). In the case of the present invention, since the contact resistance of the liquid and the like also change, it cannot be simply expressed by this equation. The pulse given must also be fast. 10
In the case of continuous driving at 0 kHz or more, the action of radiation pressure by ultrasonic waves is taken into consideration, but a driving frequency of several MHz or more is required to form a liquid column only by radiation pressure. At such a high frequency, the load on the driving device is increased. Therefore, it is desirable to form a liquid column by the flow of ink as in the present invention in terms of driving power.

The flow rate of the ink can be adjusted by the voltage value applied to the liquid column forming piezoelectric element 4. Thereby, the driving frequency and the driving voltage given to the liquid column forming piezoelectric element 4
A liquid column 1b of an arbitrary height can be formed on the free ink surface 1a.

FIG. 6 is a schematic configuration diagram of an example of an embodiment of the ink recording apparatus of the present invention. In the figure, 11, 13, 1
4, 15 and 16 are recording heads, 12 is a liquid column forming part, 17
Is an image recording medium. 1b is the liquid column described in FIGS. 1 to 4, and is formed by the liquid column forming portion 12. Of course, the above-described piezoelectric element can be used for the liquid column forming portion 12, and in addition, a configuration using thermal energy or electrostatic force may be used. In the following description, the liquid column forming part 12 will be described using a piezoelectric element.

FIG. 6A is an explanatory diagram of a recording head having a liquid column forming portion 12 provided therein. By applying a predetermined voltage at a predetermined frequency to the piezoelectric element, which is the liquid column forming section 12, the liquid columns 1b corresponding to the recording pixels are formed in a line. In addition, moving means for applying an external force for causing ink droplets to fly is also arranged corresponding to each liquid column forming section 12.

FIG. 6B is a schematic configuration diagram for performing full-color printing. The recording head 13 is Y (yellow), the recording head 14 is M (magenta), the recording head 1
Reference numeral 5 denotes recording using C (cyan) ink, and the recording head 16 performs recording using K (black) ink. Recording head 13, 1
4, 15 and 16 are arranged in tandem type for four colors. However, the present invention relates to the arrangement of the recording head,
The present invention is not limited to the configuration of FIG. 6 but is applied to various device layouts.

The image recording medium 17 is conveyed to a recording head by a conveying means (not shown). Image recording medium 17
Before reaching the recording head unit, the liquid column 1 having a predetermined height for each pixel in the recording head of each ink color is used.
b is formed. The ink is moved to the image recording medium 17 to form a desired image on the image recording medium 17 as shown in FIG. The operation of recording each pixel is performed by the flight of the ink droplet described with reference to FIG. When the image recording is completed, as shown in FIG. 6D, it is preferable from the viewpoint of energy loss that the formation of the liquid column 1b is stopped and the original flat ink free surface is obtained. However, when forming an image on an image recording medium conveyed intermittently,
The image may be recorded on the next image recording medium while the liquid column is formed. If the image recording medium 17 is always conveyed to the recording head unit, such as continuous paper,
A liquid column may be formed on a recording head of a required color only when a required image recording area passes through the recording head of each color. When the image recording area is intermittent, the liquid column may be continuously formed.

FIG. 7 is an explanatory view of another method of forming a liquid column in the recording head described in FIG. FIG. 6 has described the method of forming the liquid columns on all the print heads for each print head and the method of forming the liquid columns only on the print heads of the required colors. Therefore, the method of forming all the liquid columns in the recording head in which the liquid columns are formed has been described.

However, depending on the recorded image, it is not always necessary to form all the liquid columns for a recording head of one color. In FIG. 7, liquid columns corresponding to all pixels are not always formed during image recording, but only liquid columns corresponding to necessary pixels are selectively formed. Explaining with reference to FIGS. 6B and 6C, for example, when the recording in the transport direction (sub-scanning direction) of the image recording medium 17 is set as a column, the recorded image data is read in advance and is in a certain column. If the color record is not longer than a predetermined length, the liquid column in the row is prevented from being formed therebetween. This method can reduce the energy as compared with FIG. 6 and can freely control the wave on the entire free surface of the ink. Therefore, it is also possible to control the generated vibration wave to cancel by forming a liquid column. It becomes possible. Therefore, by selectively forming the liquid column, there is an advantage that it is possible to efficiently suppress the mutual interference between the printing portions corresponding to the adjacent pixels.

FIGS. 6 and 7 show a configuration in which the printing sections of each recording head are arranged in a line in the main scanning direction.
A configuration of a dimensional printing unit may be adopted. FIG. 8 is an example of a two-dimensional array. The formation of the liquid column is indicated by a circle. The aperture 2 is formed at the position of the circle, the ink chamber 3 and the liquid column forming section 12 are arranged below the aperture 2, and a moving means for applying an external force for causing ink droplets to fly is arranged. . FIG. 8A is a perspective view, and shows a state where a plurality of rows are arranged in the sub-scanning direction in the liquid column forming portions arranged in the main scanning direction. FIG. 8B illustrates the positional relationship in a plan view. For the first row,
The four rows are arranged such that the phase is shifted by １ ／ of the pitch P between pixels. The pitch in the sub-scanning direction was also set to P.
By moving the image recording medium by 1 / 4P,
Image recording with a pixel density four times P is possible. In addition,
In FIG. 8, the arrangement of four rows is illustrated, but the arrangement is not limited to four rows, and a two-dimensional arrangement can be performed with an arrangement of two or more rows.

FIG. 9 is an explanatory view of a first embodiment of the moving means for applying an external force to the formed liquid column. In the figures, FIGS.
The same parts as those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted. 21 is an ink support, and 22 is a top plate. In this embodiment, as in FIGS. 1 to 4, a pressure change caused by driving a piezoelectric element is used as an external force applying unit. As shown in FIG. 9 (A), the ink chamber 3 is provided in the ink support 21 and includes a substantially conical space and a cylindrical space below the space. A recording piezoelectric element 5 is provided around the cylindrical space of the ink chamber 3 so as to surround the cylindrical space. A liquid column forming piezoelectric element 4 is provided at a position corresponding to the bottom of the cylindrical space of the ink chamber 3.

A top plate 22 on which the aperture 2 is accurately formed is attached to the upper surface of the ink support 21. The upper ink layer 1 and the ink chamber 3 communicate with each other via an aperture 2 provided on the top plate 22.
As shown in FIG. 9A, by driving the liquid column forming piezoelectric element 4 at a predetermined frequency and a predetermined voltage, the liquid column forming piezoelectric element 4 is moved in the central axis direction of the cylindrical ink chamber 3. Vibrate. This causes a flow of ink from the ink chamber 3 through the aperture 2 to the free ink surface 1a,
The liquid column 1b is formed.

As shown in FIG. 9B, the recording piezoelectric element 5 vibrates in the radial direction of the cylindrical ink chamber 3 according to a recording signal. Thereby, the ink in the ink chamber 3 is
Since the volume in the ink chamber 3 is reduced, the ink is compressed in the radial direction of the cylinder, and a flow is generated toward the aperture 2. This ink flow is amplified by the conical space and the aperture 2 in the ink chamber 3 and tends to flow toward the ink free surface 1a, so that the liquid column 1b is further lifted. Since the top of the liquid column 1b is formed into droplets by a small external force and flies, the recording piezoelectric element 5 only needs to generate a smaller force than when a normal piezoelectric element is driven. The ejected ink droplets adhere to an image recording medium (not shown) to perform recording.

FIG. 9C shows an example in which the configuration shown in FIG. 9A is arranged in one line in the main scanning direction. Basically, the intervals between the ink chambers 3 need to be determined according to the resolution required for image recording. However, as described with reference to FIG. 8, the two-dimensional arrangement is arranged in a staggered arrangement. By arranging, each row may be arranged in one row at a pitch wider than the resolution required for image recording.

FIG. 10 is a modification of the first embodiment described with reference to FIG. In the figure, the same parts as those in FIG. 9 are denoted by the same reference numerals, and the description is omitted. In the above-described first embodiment, the recording piezoelectric element 5 is wound around the cylindrical ink chamber 3, but in this modified example, the recording piezoelectric element 5 is attached to a part of the wall surface inside the tube in a beam shape. That is, as shown in FIG. 10A, an ink chamber 3 having a rectangular cross section is formed in an ink support 21, a piezoelectric element 4 for forming a liquid column is provided at the bottom, and a piezoelectric element 5 for recording is provided on a side wall. Provided. The recording piezoelectric element 5 may be provided on four surfaces of the side wall, or may be provided partially, for example, on one side wall. FIG.
0 shows an example in which the recording piezoelectric element 5 is provided only on one surface. In this case as well, by driving the liquid column forming piezoelectric element 4 and forming a liquid column 1b, a recording signal is applied to the recording piezoelectric element 5 to form an ink chamber as shown in FIG. 3, the ink in the ink chamber 3 is caused to flow in the direction of the free ink surface 1a. As a result, the top of the liquid column 1b is turned into a droplet, and the ink droplet can be caused to fly to an image recording medium (not shown).

FIG. 11 is an explanatory view of a second embodiment of the moving means for applying an external force to the formed liquid column. In the figure, FIG.
The same parts as those described above are denoted by the same reference numerals and description thereof will be omitted. 2
3 is a heating element, and 24 is a bubble. In this example,
As a moving means, a bubble generated by driving the heating element 23 is used, and a pressure change due to bubble growth is used. The heating element 23 generates heat by receiving an electric signal. When an electronic signal is applied to the heating element 23 in a state where the liquid column 1b is formed as shown in FIG. 11A, the heating element 23 generates heat, and a film is formed on the surface where the heating element 23 and the ink are in contact. Boiling occurs, and bubbles (bubbles) 24 are generated. This phenomenon is a phenomenon applied to a general bubble jet type printer. Due to the growth of the generated bubbles 24, the volume in the ink chamber 3 is reduced, and the ink in the ink chamber 3 flows toward the ink free surface 1a. As a result, the top of the liquid column 1b is turned into droplets, and the ink droplets are allowed to fly and adhere to an image recording medium (not shown) to perform recording.

In the configuration using the heating element 23, the heating resistor serving as the heating element 23 is patterned to form the ink chamber 3.
, The density can be relatively easily realized.

FIG. 12 is an explanatory view of a third embodiment of the moving means for applying an external force to the formed liquid column. In the figure, the same parts as those in FIGS. 25 is a photothermal conversion layer. Also in this embodiment, an external force is applied by utilizing bubbles generated by heat. As shown in FIG. 12A, a photothermal conversion layer 25 is provided on the side wall of the ink chamber 3. In addition, the ink support 21 on the light-to-heat conversion layer 25 side can transmit light.
It is formed of a transparent material. The light-to-heat conversion layer 25 used in this embodiment is formed of a thin aluminum layer having a thickness of several μm to several tens μm, for example.

As shown in FIG. 12B, a part of the light-to-heat conversion layer 25 irradiated with light from the outside absorbs light energy and rapidly generates heat. Due to the heat generation, bubbles 24 are generated at the interface between the light-to-heat conversion layer 25 and the ink in the same manner as shown in FIG. This causes the ink in the ink chamber 3 to flow toward the free ink surface 1a. Thus, the top of the liquid column 1b can be turned into droplets, and the ink droplets can fly to an image recording medium (not shown).

FIG. 12C shows an example in which the configurations shown in FIGS. 12A and 12B are arranged in one line in the main scanning direction. In accordance with the recording signal, a spotlight-like light is applied to a position on the light-to-heat conversion layer 25 corresponding to the pixel that causes the ink droplet to fly. Then, as described above, the light-heat conversion layer 25 generates heat in the light-irradiated portion, and generates bubbles in the ink chamber 3 at the heat generation position. Thus, the ink droplet can be selectively caused to fly.

FIG. 13 is an explanatory view of a fourth embodiment of the moving means for applying an external force to the formed liquid column. In the figure, FIG.
The same reference numerals are given to the same parts as 0, and the description is omitted.
In this embodiment, as shown in FIG. 13A, an example is shown in which the liquid column forming piezoelectric element 4 is also used as the recording piezoelectric element 5. A drive signal for forming a liquid column and a drive signal based on a recording signal are applied to the piezoelectric element 4 for forming a liquid column in a superimposed manner. In this case, by modulating the pulse signal for driving the liquid column forming piezoelectric element 4, the ink droplet can be made to fly by changing the volume of the ink chamber 3 only when recording. For example, as shown in FIG. 13D, the liquid column forming piezoelectric element 4 is constantly driven by a low voltage driving signal for forming a liquid column. In this state, as shown in FIGS. 13A and 13C, only the liquid column 1b is formed, and the ink droplet does not fly. When recording,
A high-voltage recording signal is superimposed on a driving signal for forming a liquid column.
Thus, as shown in FIG. 13B, ink droplets can be made to fly onto an image recording medium (not shown) to perform recording. In such a configuration, the liquid column 1b
Formation and movement of ink droplets,
The apparatus can be manufactured at a low cost by simplifying the configuration.

In the configuration in which the recording piezoelectric element 5 is provided separately from the liquid column forming piezoelectric element 4 as shown in FIGS. 9 and 10 described above, regardless of the driving of the liquid column forming piezoelectric element 4,
The recording piezoelectric element 5 can be driven at an arbitrary timing to cause ink droplets to fly, which is advantageous for high-speed recording.

FIG. 14 is an explanatory view of a fifth embodiment of the moving means for applying an external force to the formed liquid column. In the figure, FIG.
The same reference numerals are given to the same parts as 0, and the description is omitted.
17 is an image recording medium, 26 and 27 are electrodes, and 28 is a recording signal. In this embodiment, an electrostatic attraction force is used as the external force applying means. As shown in FIG. 14A, one electrode 26 is disposed on a top plate 22 supporting the ink layer 1, and the other electrode 26 is disposed on the back side of the image recording medium 17 transported to a position facing the free ink surface 1a. Electrodes 27 are arranged. By applying a recording signal 28 between the two electrodes to form an electric field, the liquid column 1b formed on the free surface of the ink is formed.
Is configured to give an electric charge to. The electrode 26 on the ink support 21 side used here may be ring-shaped or may be separated symmetrically. The electrodes 27 arranged on the back side of the image recording medium 17 are independently arranged so as to be paired with the electrodes 26 on the ink support 21 side. Note that any one of the electrodes may be provided in common for a plurality of printing units.

As shown in FIG. 14B, the recording signal 28
Is applied between the electrodes 26 and 27, the ink support 21
If the electrode 26 on the side is a negative electrode, a positive charge accumulates below the ink in contact with the negative electrode. Conversely, on the free ink surface 1a side,-electric charges are accumulated, and-on the top of the liquid column 1b-
The electric charges are sucked toward the + electrode disposed on the back side of the image recording medium 17, and the liquid column 1 b extends toward the image recording medium 17. Further, the ink at the top of the liquid column 1b is
Torn off, it flies over the image forming medium 17. When the recording signal is extinguished and the electric field between the two electrodes is eliminated, the liquid column 1b extending by the external force in the direction of the image recording medium 17 becomes the original liquid column formed by the liquid column forming piezoelectric element 4 due to the ink surface tension. Return to height column.

In the method using such an electrostatic attraction force,
It is possible to fly ink droplets with less energy as compared with the above-described method in which the piezoelectric element or the heating element is driven. Further, since the intensity of the electric field can be controlled by controlling the voltage applied between the two electrodes, the amount of the ink droplet to be jetted can be changed. By using this, it is easy to control the gradation of the recorded image,
It is possible to record a multi-tone high-definition image.

FIG. 15 is an explanatory view of a sixth embodiment of the moving means for applying an external force to the formed liquid column. In the figure, FIG.
The same parts as in FIG. 4 are denoted by the same reference numerals, and description thereof is omitted.
In this embodiment, the basic configuration shown in FIG.
This is the same as the fifth embodiment described with reference to FIG.

When the recording signal 28 shown in FIG. 15B is applied, the top of the liquid column 1b extends due to the electrostatic attraction force.
The liquid column was allowed to adhere to the image recording medium 17 without forming a liquid droplet. This can be realized by adjusting the height of the liquid column 1b constantly formed by the liquid column forming piezoelectric element 4, the height of the image recording medium 17, and the like.

When the print signal is extinguished and the electric field between both electrodes is eliminated, as shown in FIG.
The liquid column 1b extended by the external force in the direction of 7 returns due to the surface tension of the ink, and the ink adhered on the image recording medium 17 and the liquid column 1b are cut using the returning force. The cut liquid column 1b returns to the original liquid column 1b formed by the liquid column forming piezoelectric element 4.

The method of adding the tip of the liquid column to the image recording medium without forming droplets as in this embodiment is not limited to the sixth embodiment, but can be applied to the above-described embodiments. Therefore, "moving" in the claims means that the tip of the liquid column is formed into droplets and attached to the image recording medium, or that the tip of the liquid column is attached to the image recording medium and then cut. Is included.

As described above, in the present invention, the volume changing element for changing the volume of the ink chamber 3 to always form the liquid column is used. In the above example, as this volume changing element,
An example using a piezoelectric element has been described. However, other elements may be used as long as the liquid column 1b can be formed on the free ink surface 1a by periodically changing the volume in the ink chamber 3.

As described above, in the present invention, since the liquid column 1b is always formed by using the volume changing element, the liquid column 1b propagates along the ink free surface 1a even in a configuration in which a plurality of ink chambers and the volume changing element are arranged. The effect of the interfering waves can also be reduced. Further, since energy is given to the liquid column 1b in advance, the force (energy) required to move the ink from the liquid column 1b to the image recording medium is a conventional nozzleless method for ejecting ink droplets from a state where there is no liquid column. It may be less than the method. Therefore, the force of the waves coming from the other printing units is weaker than before, and the mutual interference of the printing units is further reduced. The fact that the force for moving the ink to the image recording medium may be smaller than before, which also reduces the residual vibration remaining in the printing unit after recording. That is, according to the present invention, two types of mutual interference due to the wave propagating on the ink surface and residual vibration remaining in the printing portion after recording.
It is possible to obtain a significant improvement effect on the two issues.
In the present invention, liquids other than ink can be used in the same manner.

[0060]

As is apparent from the above description, according to the present invention, when printing is performed in a printing apparatus having a nozzleless configuration, the problem of mutual interference between adjacent printing sections and the residual vibration after printing are reduced. The residual vibration amplitude and the residual vibration convergence time are about 1/2 to 1/3 of the conventional one.
It is possible to reduce to the extent. Therefore, it is possible to provide a high-speed recording apparatus capable of performing stable recording without providing a time delay for each recording.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a principle configuration of the present invention, and is an explanatory view of a behavior of an ink free surface when a volume of an ink chamber is changed.

FIG. 2 is an explanatory view of a principle configuration of the present invention, and is an explanatory view of a behavior of an ink free surface when the volume of an ink chamber is increased immediately after the volume is reduced.

FIG. 3 is an explanatory diagram of a principle configuration of the present invention, and is an explanatory diagram of a behavior of an ink free surface when a volume of an ink chamber is continuously increased and decreased.

FIG. 4 is an explanatory diagram of a process of flying ink droplets.

FIG. 5 is a graph showing an example of the relationship between the energy of external force and the vibration amplitude and vibration time of the liquid surface.

FIG. 6 is a schematic configuration diagram illustrating an example of an embodiment of an ink recording apparatus according to the invention.

FIG. 7 is an explanatory diagram of another method of forming a liquid column in the recording head described in FIG.

FIG. 8 is an explanatory diagram of another configuration example of the recording head.

FIG. 9 is an explanatory view of a first embodiment of a moving means for applying an external force to the formed liquid column.

FIG. 10 is a modification of the first embodiment described with reference to FIG.

FIG. 11 is an explanatory view of a second embodiment of the moving means for applying an external force to the formed liquid column.

FIG. 12 is an explanatory view of a third embodiment of the moving means for applying an external force to the formed liquid column.

FIG. 13 is an explanatory view of a fourth embodiment of the moving means for applying an external force to the formed liquid column.

FIG. 14 is an explanatory view of a fifth embodiment of the moving means for applying an external force to the formed liquid column.

FIG. 15 is an explanatory view of a sixth embodiment of the moving means for applying an external force to the formed liquid column.

[Explanation of symbols]

1 ... ink layer, 1a ... free surface of ink, 1b ... liquid column, 1
c: concave portion, 2: aperture, 3: ink chamber, 4: piezoelectric element for forming a liquid column, 5: piezoelectric element for recording, 11, 13, 1
4, 15, 16: recording head, 12: liquid column forming part, 17
... image recording medium, 21 ... ink support, 22 ... top plate, 2
3 heating element, 24 bubble, 25 light-to-heat conversion layer, 2
6, 27 ... electrodes, 28 ... recording signals.

Continued on the front page F term (reference) 2C056 EA01 FA02 FA03 FA04 FA07 HA05 HA19 2C057 AF01 AG21 AR12 BA13 BD05 BF06

Claims (16)

[Claims] 1. A recording apparatus for moving a liquid from a free surface of the liquid and attaching the liquid to an image recording medium at a position facing the free surface of the liquid to perform recording, wherein the free surface of the liquid is formed. A liquid layer, a liquid chamber communicating with the liquid layer via an aperture, a volume changing element provided in the liquid chamber and capable of changing the volume in the liquid chamber, and driving the volume changing element. By changing the volume of the liquid chamber to repeatedly generate an ink flow generated toward the free surface of the liquid through the aperture, a liquid column having a constant height is formed on the free surface of the liquid. A recording apparatus comprising: a driving unit; and a moving unit that moves a liquid from the liquid column to the image recording medium. 2. The recording apparatus according to claim 1, wherein a plurality of the liquid chambers are provided, and the volume changing element and the moving unit are provided corresponding to each of the liquid chambers. 3. The recording apparatus according to claim 1, wherein the volume changing element is a piezoelectric element. 4. The apparatus according to claim 1, wherein the moving means is a piezoelectric element, and moves the liquid to the image recording medium by using a volume change generated by driving the piezoelectric element. Item 4. The recording device according to any one of Items 3. 5. The moving means is a heat generating mechanism, which generates bubbles in the liquid by the heat generating mechanism, and moves the liquid to the image recording medium using pressure received from the bubbles. The recording apparatus according to claim 1, wherein: 6. The driving means uses the same piezoelectric element as the volume changing element as the moving means, and the driving means superimposes a recording signal for moving a liquid to the image recording medium on a driving signal for forming the liquid column. The recording apparatus according to claim 3, wherein the piezoelectric element is driven by driving the piezoelectric element. 7. The moving means is arranged on a first electrode disposed on a substrate supporting the liquid layer, and on a surface of the image recording medium opposite to a surface facing the free surface of the liquid. A liquid electrode formed on a free surface of the liquid by transmitting an image recording signal between the first electrode and the second electrode, thereby providing an electrostatic attraction force; The recording apparatus according to any one of claims 1 to 3, wherein the liquid is moved to the image recording medium by utilizing the liquid. 8. The image forming apparatus according to claim 1, wherein the moving unit changes the liquid in the liquid column into droplets, causes the liquid to fly, and attaches the liquid to the image recording medium. Recording device. 9. A recording method in which a liquid is moved from a free surface of a liquid and the liquid is attached to an image recording medium at a position facing the free surface of the liquid to perform recording, wherein the free surface of the liquid is formed. A liquid layer that communicates with the liquid layer via an aperture, the ink chamber flowing toward the free surface of the liquid through the aperture by changing the volume of the liquid chamber. A recording method comprising: forming a liquid column having a predetermined height on a free surface of the liquid by repeatedly generating the liquid; and moving the liquid from the liquid column to the image recording medium to perform recording. 10. The recording method according to claim 9, wherein a plurality of the liquid chambers are provided, a liquid column is formed for each liquid chamber, and the liquid is independently moved to the image recording medium. 11. The recording method according to claim 9, wherein the liquid column is formed by changing a volume of the liquid chamber by driving a piezoelectric element. 12. The liquid ejecting apparatus according to claim 9, wherein a liquid is moved from the liquid column to the image recording medium by a pressure change generated by driving a piezoelectric element. Recording method. 13. The method according to claim 9, wherein a bubble is generated in the liquid using a heat generating mechanism, and the liquid is moved to the image recording medium by utilizing a pressure received from the bubble. Or the recording method according to item 1. 14. The piezoelectric element is further distorted by superimposing another recording signal on a drive signal applied to the piezoelectric element for forming the liquid column, thereby further changing the volume of the liquid chamber. The recording method according to claim 11, wherein the liquid is moved to the image recording medium. 15. The liquid column formed on a free surface of the liquid is provided with an electric charge, and the liquid is moved to the image recording medium using an electrostatic attraction force. 12. The recording method according to any one of items 11 to 11. 16. The method according to claim 9, wherein when the liquid is moved from the liquid column to the image recording medium, the liquid in the liquid column is formed into liquid droplets, flies, and moves to the image recording medium. The recording method according to claim 15.