JPH10109422A - INK JET HEAD AND INK JET RECORDING APPARATUS HAVING THE SAME - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the stability and reliability of an ink landing point by making it possible to reduce the voltage for generating and flying ink microdroplets, to increase the density of an ink jet head, and to reduce the cost. . The inkjet head has a plurality of channels and a piezoelectric element provided for each channel. An intermediate transfer belt is provided near the ink ejection port 48. The intermediate transfer belt has an ink ejection port 4
8, the voltage required for generating and flying the ink can be reduced, and the stability and reliability of the ink landing point can be improved. Since the piezoelectric elements 44 are provided for each channel 45, the density of the ink jet head 41 can be increased. Since the common electrode 50 shares the channel selection electrode portion and the elastic wave generation electrode portion, the number of wires per channel 45 can be reduced, and the cost of the circuit can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet head and an ink-jet recording apparatus having the same, and more particularly, to a method for generating and flying fine ink droplets at a low voltage and increasing the density of the head to achieve high definition. The present invention relates to an ink jet head capable of recording and an ink jet recording apparatus including the same.

[0002]

2. Description of the Related Art Conventionally, the following are known as an electrostatic suction type ink jet head and an ink jet recording apparatus having the same. FIG.
FIG. 1 is a front view illustrating a configuration of an inkjet recording head 1 disclosed in Japanese Patent No. 9189. The ink jet recording head 1 includes a pair of plate members 2 and 3, a recording electrode array 4, a control electrode array 5, a plurality of recording power supplies 6, and a plurality of control signal sources 7.

A pair of plate members 2 and 3 are provided at an interval from each other, and a slit plate interval 8 is formed. The ink 9 fills the gap 8 between the slits. The ink 9 in the slit plate interval 8 is subjected to static pressure by the ink in an ink container (not shown), and a half-moon-shaped convex surface, that is, a meniscus is formed at the ink ejection port. A recording electrode array 4 is disposed at an end of the inner surface of the plate member 2 which is in contact with the outside. At a position facing the recording electrode array 4, a recording paper (not shown) and an installed counter electrode are arranged via a space.
A control electrode row 5 is arranged at an end of the plate-shaped member 3 which is in contact with the outside. Each control electrode of the control electrode row 5 is provided to face each of the four recording electrodes of the recording electrode row 4.
Each recording power source 6 is connected to each recording electrode of the recording electrode array 4, and each control signal source 7 is connected to each control electrode of the control electrode array 5.

A recording power supply 6a applies a voltage equal to or higher than a threshold value to each one of the recording electrode rows 4 of the recording electrode array 4.
In addition, a voltage lower than the threshold voltage from the recording power supplies 6b, 6c, 6d is applied to the remaining recording electrodes of each recording electrode array 4. A voltage equal to or higher than the threshold voltage is applied to one of the control electrodes 5 from the control signal source 7a. Voltages lower than the threshold voltage are applied to the remaining control electrodes of the control electrode row 5 from the other control signal sources 7b to 7n. At this time, only the ink 9 near the recording electrode at the left end in FIG. 18 has a voltage equal to or higher than the threshold voltage, and the ink 9 is more easily ejected than the other ink surface portions. In this way, the ink 9 near the recording electrode is ejected from the ink ejection port by the electrostatic attraction force generated between the counter electrode and the meniscus, and ink droplets are formed on the recording paper provided between the counter electrode and the meniscus. The recording is performed by forming the recording pixels by adhering.

FIG. 19 is a diagram showing the configuration of an ink jet recording apparatus 11 disclosed in Japanese Patent Laid-Open Publication No. Hei 3-5150. The ink jet recording apparatus 11 includes a recording head 16 having an ink container 13 for accommodating ink 12, a needle-shaped recording electrode 14, and ultrasonic vibrating means 15, and a counter electrode 1
7 and voltage application control means 18.

The recording head 16 has an ink container 13 formed in a container shape having a U-shaped cross section with an open upper end. The ink container 13 contains ink 12. A small insertion hole 19 through which a needle-shaped recording electrode 14 is inserted is formed at the center of the bottom of the ink storage unit 13, and the recording electrode 14 is inserted into the ink storage unit 13 through the insertion hole 19. It is disposed in the ink 12, and its tip slightly projects from the surface of the ink 12.

The lower end of the recording electrode 14 is fixed to the ultrasonic vibrating means 15. This ultrasonic vibration means 15
It has a laminated piezoelectric vibrator.

At a position facing the recording head 16,
At a predetermined interval, a roll-shaped counter electrode 17 which also functions as a support surface of the recording sheet is arranged. The counter electrode 17 is driven to rotate at a constant speed or intermittently by a drive motor (not shown) or the like. Further, between the recording electrode 14 and the counter electrode 17, a voltage application control means 18 for applying a voltage for forming an electric field between the electrodes 14, 17 is provided.

In the above-described configuration, the ink 12 is supplied to the ink container 13 and the counter electrode 17 is driven to rotate while the recording sheet is wound around the counter electrode 17. In this state, ultrasonic vibration is applied to the recording electrode 14 by the ultrasonic vibration means 15, and the ink 12 is transported by the ultrasonic vibration to form a film of the ink 12 along the tip of the recording electrode 14. Is formed. Voltage application control means 1 between recording electrode 14 and counter electrode 17
By applying a pulse voltage according to the image information by 8, an electric field is formed between the recording electrode 14 and the counter electrode 17. Since the ink 12 has conductivity, charges are given to the surface of the ink 12 from the recording electrodes 14, the charges are concentrated on the tips of the convex meniscus, and the electrostatic force between the recording electrodes 14 and the counter electrode 17 is increased. The ink 12 at the tip of the meniscus flies due to the suction force. In this way, the flying ink 12 adheres to the recording sheet and recording is performed.

FIG. 20 is a diagram showing a configuration of an ink jet printer disclosed in Japanese Patent Laid-Open No. 2-198853, and FIG. 21 is a perspective view of a part of FIG.

The ink jet recording head 21 has a head main body 26 made of a square material made of metal such as stainless steel. In the head main body 26, an ink flow path 27 having a circular cross section is formed in a penetrating manner. I have. On one side surface of the head main body 26, a slit-shaped ink discharge port 28 having a predetermined interval is formed along the longitudinal direction of the head main body 26.
It communicates with the ink flow path 27.

The head main body 26 is horizontally disposed such that the ink discharge ports 28 face upward.
Pass over the ink ejection port 28. The discharge holes 25 are provided for discharging ink as needed. Ink is introduced from an ink supply device 22 through an ink supply port 23 into an ink flow path 27 in the head main body 26. The ink is supplied to the ink discharge port 28 communicating with the ink flow path 27 at a predetermined ink meniscus. Is formed and held.

A temperature control device 29 is provided on the back of the head main body 26. At both ends of the head body 26,
An ultrasonic exciter 30 and an ultrasonic absorber 31 are provided.
At a position facing the ink ejection port 28, an electric field forming electrode (not shown) for causing ink to fly is provided. Ultrasonic waves are generated by the ultrasonic exciter 30 and the traveling waves of the ultrasonic waves are transmitted to the ink flow path 27 and the ink ejection port 2.
8, the ultrasonic vibration is a compression wave as shown in FIG. 22 and the density of the ink is constant, so that the surface of the ink held at the opening end of the ink discharge port 28 has A ridge 32 corresponding to a dense portion of the ultrasonic vibration is formed. The raised portion 32 of the ink moves along the longitudinal direction of the ink discharge port 28 with the progress of the ultrasonic vibration. Ultrasonic waves propagating in the ink flow path 27 and the ink discharge ports 28 are absorbed by an ultrasonic absorber 31 provided at an end of the head main body 26, and reflected by the ink flow path 27 and the ink discharge ports 28. Does not occur.

FIG. 23 is a diagram showing a raised portion 32 of the ink generated by applying a pulse-like voltage to the ultrasonic exciter 30, and FIG. 24 is a diagram showing the generation of a sine wave-like voltage to the ultrasonic exciter. FIG. 4 is a diagram illustrating a raised portion 32 of ink to be printed. When a pulsed voltage is applied, the raised portion 32 on the ink surface advances independently. When a sinusoidal voltage is applied, raised portions 32 are formed on the surface of the ink at a constant period, and the raised portions 32 travel.

As described above, when a voltage is applied to the above-mentioned electric field forming electrode in accordance with an image signal, an electrostatic field is generated in the raised portion 32 of the ink caused by the propagation of the ultrasonic wave, and the tip of the raised portion 32 is formed. The charge is concentrated at the
An electrostatic attraction force acts on 2. Then, the ink in the raised portions 32 flies toward the electric field forming electrodes, adheres to the recording sheet 24, and performs recording.

[0016]

However, in the prior art in which the ejection channel is selected by controlling the meniscus shape in the electrostatic suction system, the density of the head is reduced, the cost is reduced, and the stability and reliability of the ink droplet landing point are improved. There is a problem that it is difficult to secure the quality. That is, in the ink jet recording head 1 shown in FIG. 18, recording power supplies 6 a to 6 d are individually provided for each recording electrode of the recording electrode row 4, and the control electrode row 5 is provided.
Since the control signal sources 7a to 7n are individually provided, large power is required for the ink 9 to fly, and there is a problem that the driving cost increases.

In the ink jet recording apparatus shown in FIG. 19, in order to increase the density of the head, it is necessary to provide needle-like recording electrodes 14 at a high density. Since each is required,
It is necessary to reduce the size of the ultrasonic vibration means 15 and perform high-density mounting, and it is difficult to increase the density of the head.

In the ink jet printer shown in FIGS. 20 to 24, since the ink discharge port 28 has a slit shape and the ink raised portion 32 is always moving, it is necessary to fly the ink accurately and to a specific position depending on the temperature or the like. There is a problem that it is difficult due to a change in the propagation speed of the wave, and the attenuation of the wave due to the viscosity of the ink is also a problem, and it is difficult to ensure the stability and reliability of the ink droplet landing point.

An object of the present invention is to generate and fly ink microdroplets at a low voltage, to increase the density and cost of an ink jet head, and to improve the stability of ink droplet landing points and An object of the present invention is to provide an ink jet head capable of improving reliability and an ink jet recording apparatus including the same.

[0020]

SUMMARY OF THE INVENTION According to the present invention, a plurality of ink passages having ink discharge ports which open toward an ink droplet deposition medium are separately formed, and each ink passage is a storage in which ink is stored. The ink is guided to each ink passage in common with the ink passage, and a channel selection voltage is applied between the ink droplet application medium and the ink interface facing the ink droplet application medium from the ink ejection port, and the ink is applied from the ink interface. In an ink jet head that causes ink droplets to fly onto an ink droplet-attached medium by electrostatic attraction, elastic wave generating means for applying an elastic wave to ink in each ink passage is provided in each ink passage individually for each ink passage. An inkjet head characterized by being provided. According to the present invention, in each ink passage, an elastic wave generating means for applying an elastic wave to the ink in each ink passage is provided individually for each ink passage. The interface can be formed in a convex shape, a minute droplet of ink can be generated and fly for each ink passage, and an elastic wave generating means is provided for each ink passage to increase the density of the ink jet head. And the stability and reliability of the landing point of the ink droplet can be improved.

The elastic wave generating means according to the present invention is characterized in that the elastic wave generating means is a piezoelectric element for generating a pressure wave having a frequency of 1 to 16 kHz to the ink in each ink passage. According to the present invention, since the elastic wave generating means is a piezoelectric element for generating a pressure wave having a frequency of 1 to 16 kHz to the ink in each ink passage, the generated pressure wave is generated at the ink interface of the ink discharge port. The shape can be projected in a convex shape toward the ink droplet application medium at a cycle based on the frequency.

Further, the elastic wave generating means of the present invention is a piezoelectric element for generating a surface acoustic wave that gives a surface acoustic wave having a frequency of 1 to 300 MHz traveling toward the ink interface to the ink in each ink passage. Features. According to the present invention, the elastic wave generating means may apply a frequency of 1 to 300 MHz to the ink in each ink passage toward the ink interface.
The surface acoustic wave is a piezoelectric element for generating surface acoustic waves, and the generated surface acoustic waves form minute protrusions at the ink interface of the ink ejection ports at a cycle based on the frequency, and the ink is easily ejected by electrostatic attraction. Drops can fly.

Further, the elastic wave generating means of the present invention is characterized in that a pressure wave having a frequency of 1 to 16 kHz and a frequency of 1 to 300 M
It is a piezoelectric element for generating a superimposed elastic wave which superimposes a surface acoustic wave of 1 Hz. According to the present invention, since the elastic wave generating means is a piezoelectric element for generating a superposed elastic wave that superimposes a pressure wave and a surface acoustic wave on ink in each ink passage, the generated superposed elastic wave is The ink interface of the ejection port is made to have a convex shape with a cycle based on the frequency of the pressure wave, and fine projections are formed on the surface with a cycle based on the cycle of the surface acoustic wave, so that the ink can easily fly by electrostatic attraction. .

Further, the piezoelectric element according to the present invention has a common electrode formed on one surface of the substrate facing the ink passage, and a remaining area near the ink discharge port on the common electrode except for a channel selection electrode portion. And a separate electrode formed on the piezoelectric film. According to the invention, the piezoelectric element has a common electrode formed on the substrate, a piezoelectric film formed on the common electrode, and an individual electrode formed on the piezoelectric film. Since the common electrode includes an electrode portion for forming an electric field between an electrode portion for channel selection near the ink ejection port and an individual electrode for generating an elastic wave on the piezoelectric film, the electrode portion is divided. Thus, the number of wirings can be reduced as compared with the case where a circuit is configured, and the cost of the circuit can be reduced.

Further, the piezoelectric element according to the present invention has a common electrode formed on one surface of the substrate facing the ink passage, and a remaining area excluding the channel selection electrode portion near the ink discharge port on the common electrode. And a pressure wave generating individual electrode formed in a planar shape on the piezoelectric film. According to the present invention, the individual electrodes formed on the piezoelectric film are planar, and a voltage is applied between the common electrode and the individual electrodes. Waves can be generated.

Further, the piezoelectric element of the present invention has a common electrode formed on one surface of the substrate facing the ink passage, and a remaining area excluding the channel selection electrode portion near the ink ejection port on the common electrode. And two individual electrodes for generating surface acoustic waves formed on the piezoelectric film in a comb-like shape at intervals in the longitudinal direction of the piezoelectric film. According to the present invention, the two individual electrodes formed on the piezoelectric film are formed in a comb-like shape at intervals in the longitudinal direction of the piezoelectric film, and a voltage is applied between the individual electrodes. The piezoelectric element can generate a surface acoustic wave that forms minute projections at the ink interface.

Further, the piezoelectric element of the present invention has a common electrode formed on one surface of the substrate facing the ink passage, and a remaining area excluding the channel selection electrode portion near the ink ejection port on the common electrode. A piezoelectric film to be formed, an individual electrode for pressure wave generation formed in a planar shape on the piezoelectric film, and a longitudinal direction of the piezoelectric film closer to the ink ejection port than the individual electrode for pressure wave generation on the piezoelectric film. And two comb-shaped individual electrodes for generating surface acoustic waves which are spaced apart from each other in the direction. According to the present invention, the individual electrode formed on the piezoelectric film has an individual electrode formed in a planar shape and two individual electrodes formed in a comb shape, and has a common electrode and a planar individual electrode. Since the voltage is applied between the individual electrodes and between the comb-shaped individual electrodes, the piezoelectric element can generate a superimposed elastic wave that forms the entire surface of the ink interface in a convex shape and forms minute projections on the surface. .

Further, one end of an individual electrode is connected to the common electrode of the present invention, and an elastic wave is generated between the electrodes in order to cause the ink droplet to fly from the ink interface to the ink droplet applying medium by electrostatic attraction. A channel selection voltage on which a voltage for generating an elastic wave is superimposed is applied. According to the invention, one end of the individual electrode is connected to the common electrode. That is, since the common electrode shares the electrodes facing the individual electrodes, the number of wires per channel can be reduced. Further, since the channel selection voltage is applied between the electrodes, an elastic wave can be generated by the piezoelectric element when a channel is selected.

Further, according to the present invention, an ink droplet-adhering medium and a plurality of ink passages each having an ink discharge port opening toward the ink-drop-adhering surface of the ink droplet-adhering medium are formed by being individually partitioned. The ink is guided to each ink passage in common communication with the storage unit where the ink is stored, and in each ink passage, elastic wave generating means for applying an elastic wave to the ink in each ink passage is provided for each ink passage. The channel is selectively provided between the ink droplet application medium and the ink interface of the ink ejection port while applying an elastic wave to the ink in the ink passage by the elastic wave generating means to generate an electrostatic attraction force. And an ink jet head for causing ink droplets to fly from the ink interface to the ink droplet adhering surface of the ink droplet adhering medium, and a recording area of the recording paper provided in a predetermined transfer area of the ink droplet adhering medium. Facing the ink-dropping surface of the ink-dropping medium, intermittently moving the recording paper at a predetermined feed speed, and sequentially updating the recording area; When the area where the ink droplets have adhered on the ink droplet adhering surface is disposed in the transfer area, the ink adhering medium is pressed in a direction approaching the recording area of the recording paper, and the area where the ink droplets adhere is recorded on the recording paper. And a transfer unit for transferring the image in contact with a recording area. According to the present invention, since the ink droplets are arranged close to the ink discharge ports of the ink jet head, the voltage required for generating and flying the ink droplets can be reduced. In addition, in the ink jet head recording apparatus, minute droplets of the ink fly from the ink jet head toward the ink-attached medium, and the minute droplets of the attached ink are transferred to the recording area of the recording paper via the ink droplet-attached medium and recorded. High resolution, quality and print or print image can be obtained.

[0030]

FIG. 1 is an exploded perspective view showing an ink jet head 41 according to an embodiment of the present invention. The inkjet head 41 includes a cover plate 42
, A substrate 43, and a plurality of piezoelectric elements 44 for generating surface acoustic waves, which are elastic wave generating means. The cover plate 42 is a rectangular plate.
A channel 45 serving as an ink passage, an ink storage section 46, and an ink supply pipe 47 are provided. Each channel 45 is a concave groove provided in the cover plate 42 which is continuous with one end of a pair of opposing surfaces and is formed of a surface perpendicular to each inner surface. Each channel 45 is provided in parallel with a space between each other. One end of each channel 45 is opened to face an ink droplet deposition medium (not shown) to form an ink discharge port 48. The other end of each channel 45 is commonly connected to an ink storage unit 46 that stores conductive ink (hereinafter simply referred to as ink). An ink supply pipe 47 having a through hole 49 extending toward the ink storage section 46 is provided to protrude from one side of the cover plate 41 near the ink storage section 46.

The substrate 43 is a rectangular plate made of silicon. A plurality of surface acoustic wave generating piezoelectric elements 44 are provided on the substrate 43. Each piezoelectric element 44 has a common electrode 5
0, the piezoelectric film 51, and the individual electrodes 52.
Each common electrode 50 is formed on one surface facing each channel 45 of the substrate 43, has the same interval as the interval between the channels 45, and is provided in a comb shape over the entire longitudinal direction of the substrate 43. The piezoelectric film 51 is formed in a predetermined region on the common electrode 50 except for the vicinity of the ink discharge port 48 by a hydrothermal method.

The individual electrode 52 is provided on the piezoelectric film 51. This individual electrode 52 is formed by a first extension 53 extending in the longitudinal direction from the common electrode 50 near one end of the piezoelectric film 51.
A plurality of first electrodes 54 formed perpendicularly to the first extending portion 53 and at a predetermined interval from each other,
A first electrode portion 55 provided in parallel with the common electrode 50 at an interval; a second electrode portion 56 extending over the piezoelectric film 51 from one end of the first electrode portion 55; A second extending portion 57 extending in parallel with the first extending portion 53 at a distance from each other, and a second extending portion 57 extending from the second extending portion toward the first extending portion and having the same interval as each first electrode 54. And a second electrode 58 formed in the form of a comb.

The cover plate 42 and the substrate 43 are fixed so that each piezoelectric element 44 is accommodated in each channel 45.

In each channel 45, each piezoelectric element 44 for giving an elastic wave to the ink in each channel 45 is individually provided for each channel 45. (Hereinafter, also referred to as a meniscus), which can generate and fly a fine droplet of ink for each channel. Also, the piezoelectric element is provided for each channel so that the height of the inkjet head 41 can be increased. Density can be increased. One end of the individual electrode 52 is connected to the common electrode 50, and the common electrode 50 is connected between the channel selection electrode portion near the ink ejection port 48 and the individual electrode 52 for generating an elastic wave on the piezoelectric film 51. And an electrode portion for forming an electric field, the number of wirings per channel 45 can be reduced as compared with the case where a circuit is formed by dividing the two electrode portions, thereby reducing the cost of the circuit. Can be. Further, since the elastic wave travels toward the ink ejection port 48 and ejects the ink droplet from the ink ejection port 48, the ink droplet is ejected from the selected channel 45, and the ink droplet is ejected regardless of disturbance such as temperature. Can land at the desired position,
It is possible to improve the stability and reliability of the ink dropping point.

Here, the dimensions of the ink jet head 41 are such that the channel width b is, for example, about 50 μm, the channel height h is, for example, about 60 μm, the channel length L is, for example, about 30 mm, and the channel interval p1 is, for example, 80 μm.
m. The lengths L1, L2 of the first and second extending portions 53, 57 are, for example, about 4 mm, respectively, and the pitch p2 between the first and second electrodes 54, 58 is, for example, 20.
The distance d between the first and second extending portions 53 and 57 is, for example, about 60 μm.

In the above embodiment of the present invention, the shape of the individual electrode 52 is a comb-shaped electrode, but the shape of the electrode is a plane or a combination of the plane and the comb. You may.

FIG. 2 is a perspective view showing the structure of the recording section 61 of the ink jet recording apparatus. The recording unit 61 includes an intermediate transfer belt 63 serving as an ink droplet adhesion medium, a recording power source 64, and a channel selecting unit 65 for the four inkjet heads 41 and the opposing electrodes 62. Each inkjet head 41 is filled with ink colored black (black), cyan (blue), magenta (red), and yellow (yellow), respectively. Each ink jet head 41 is arranged with an ink discharge port array 59 aligned in a direction perpendicular to the longitudinal direction of the intermediate transfer belt 63, and the intermediate transfer belt 63 and the counter electrode 62 face the ink discharge port 48. They are spaced in order. The intermediate transfer belt 63 is a dielectric, for example, an endless belt made of a material in which tin fine particles are dispersed in polyetherimide. Distance D between each inkjet head 41 and counter electrode 62
Is, for example, about 0.2 to 1 mm. Counter electrode 62
A recording power supply 64 is provided between the
And the channel selection means 65 are connected in series, and the voltage Vb of the recording power supply 64 is applied between the common electrode and the counter electrode 62.
Is applied. The applied voltage Vb of the recording power supply 64 is, for example, 1 to 2.5 kV. The channel selection means 65 applies a channel selection voltage Vc to the piezoelectric element of each channel 45 according to the recording information. This channel selection voltage Vc
Is a pulsed voltage of 200 to 300 V, for example.

Here, the above-described piezoelectric element 4 for generating surface acoustic waves.
4 is applied with a channel selection voltage Vc on which a voltage for generating a surface acoustic wave having a frequency of x to 300 MHz is superimposed, a surface acoustic wave described later is generated due to distortion between the comb-shaped electrodes, and the comb-shaped electrodes A pressure wave is generated by the distortion of the piezoelectric film between the electrode and the common electrode. This pressure wave has a smaller strain than the strain generated by a planar electrode in place of the above-mentioned comb-shaped electrode.

Therefore, the meniscus when a pressure wave is generated using the comb-shaped electrode is smaller than the convex shape of the meniscus generated by the planar electrode. Can also protrude to form minute projections described later. The electric charge concentrates on the minute projections, and the electrostatic attraction force causes the ink to be ejected from the ink ejection port 48 toward the intermediate transfer belt 63.
The minute droplets of the ink fly and adhere to the ink droplet adhering surface of the intermediate transfer belt 63. The size of the recording head including the four inkjet heads 41 is, for example, 20
The height H is, for example, about 40 mm, and the length L3 is, for example, about 50 mm.

FIG. 3 shows an ink jet head 4 according to the present invention.
1 is a configuration diagram of a color serial printer 71 provided with a printer 1; A color serial printer 71, which is an ink jet recording apparatus, includes a plurality of ink jet heads 41, an intermediate transfer belt 63, a pair of pulleys 72, a transfer roller 73, which is a transfer unit, and a platen 75, which is a recording paper feed unit. .

As described above, each of the ink jet heads 41 is provided for each of the four colors, and the ink ejection port arrays are arranged in a direction perpendicular to the longitudinal direction of the intermediate transfer belt 63. The intermediate transfer belt 63 is arranged near the ink ejection port of the ink jet head 41 in an ink droplet attachment area D1 where an ink droplet attachment surface 77 is provided with a counter electrode (not shown).

The pair of pulleys 72a and 72b are spaced apart in the main scanning direction from the driving pulley 72a and the driving pulley 72a rotatably provided by a pulley driving means (not shown) around a rotation axis perpendicular to the main scanning direction. And a driven pulley 72b rotatably provided about a rotation axis perpendicular to the main scanning direction. A beltless intermediate transfer belt 63 is wound and stretched between the pulleys 72a and 72b. Here, the dimensions of the intermediate transfer belt 63 are, for example, 1/2 inch in width, 60 μm in thickness, and 66 cm in circumference.

One tension portion 80 of the intermediate transfer belt 63
a and the other tension portion 80b and each pulley 72a,
A transfer roller 73 is provided between 72b.

The transfer roller 73 is rotatably and movably provided, and is provided at a position where the intermediate transfer belt 63 can be pressed over the recording area of the recording paper 74 on the recording paper 74 supported by the platen 75 during recording. . The platen 75 is rotatably provided around an axis longer than the width of the recording paper 74, and is made of a resilient and flexible material such as rubber. 78, and a shaft 79 having a length longer than the axial length. The rotation axis of the platen 75 is provided in a direction parallel to the main scanning direction. The platen 75 is provided in a predetermined transfer area of the intermediate transfer belt 63, and
2 has a platen driving means (not shown) for intermittently moving the recording paper 74 at a predetermined feed speed while facing the ink droplet adhering surface 77 of the intermediate transfer belt 63 to sequentially update the recording area D2. ing. By rotating the platen 75 in the feed direction, the recording paper 74 is rotated.
Can move in the sub-scanning direction. Cleaner 7
Reference numeral 6 is provided for removing the remaining ink droplets after the transfer of the ink droplets to the recording paper 74.

The recording operation on the recording paper 74 will be described. Ink droplets adhere from the ink ejection ports of the ink jet head 41 to the ink droplet attaching surface 77 of the ink droplet attaching area D1 according to the recording information. At this time, the transfer roller 73 is located at a position where the intermediate transfer belt 63 cannot be pressed. Next, the pulleys 72a and 72b are rotated in the direction of arrow A to move the area of the intermediate transfer belt 63 where the ink droplets adhere to the ink droplet adhering surface 77 to a predetermined transfer area.
At a predetermined speed in the direction of arrow B. Next, the transfer roller 73 moves to a position where the intermediate transfer belt 63 can be pressed, and then presses the intermediate transfer belt 63 in a direction approaching the recording area D2 of the recording paper 74 to record the area where the ink droplets adhere. The recording paper 74 is brought into contact with the recording area of the paper
Transfer ink droplets to Next, the pressing state of the pressing roller 73 against the intermediate transfer belt 63 is released, and the intermediate transfer belt 6 is released.
3 and the recording paper 74 are moved in the directions of arrows A and B, and the remaining ink droplets on the ink droplet adhering surface 77 are removed by the cleaner 76.

The ink adhesion surface 77 of the intermediate transfer belt 63
Is arranged close to the ink ejection port of the inkjet head 41, so that it is possible to generate and fly ink droplets at a low voltage. Also, a color serial printer 7
Reference numeral 1 denotes a minute droplet of ink flying from the ink ejection port of the ink jet 41 toward the intermediate transfer belt 63 and attaching to a predetermined position on the ink droplet attaching surface 77 of the intermediate transfer belt 63. The area where the ink droplets are attached is moved to a predetermined transfer area, and the recording paper 74 is intermittently moved by a platen 75. When the recording paper is placed in the transfer area, the intermediate transfer belt 63 is moved by the transfer roller 73 to the recording paper 74. Is pressed in a direction approaching the recording area D2, and the area to which the ink droplets are attached is brought into contact with the recording area D2 of the recording paper 74 to transfer and record. The height of the ink droplets can be increased by stabilizing the ink droplet landing points caused by the ejection of the ink droplets from the channel of the selected inkjet head 41. It is possible to improve the quality of the printing or indicia image Te.

FIG. 4 is a cross-sectional view of the channel 45 when the elastic wave generating means according to another embodiment of the present invention is a pressure wave generating piezoelectric element 81, and FIG. −
FIG. 6 is a sectional view taken along line V-V of FIG.
It is sectional drawing seen from VI. In the present embodiment, portions corresponding to the configuration of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. The pressure wave generating piezoelectric element 81 includes a common electrode 50, a piezoelectric film 51, and an individual electrode 82 for generating a pressure wave.
It is comprised including. Individual electrode 82 for pressure wave generation
Is formed in a planar shape on one surface of the piezoelectric film facing the cover plate 42, and one end thereof is connected to the common electrode 50.
Further, the bottom of the substrate 83 is provided thinner than the portion where the piezoelectric film 51 is provided. This is provided to facilitate the unimorph deformation described later and to reduce the influence of the unimorph deformation on the adjacent channel.

Here, the principle of generating a pressure wave in the ink 84 using the piezoelectric element 81 for generating a pressure wave will be described.
The shape of the meniscus 85 of the ink 84 in the ink ejection port 48 is concave due to the surface tension at the ink ejection port 48 when the back pressure of the ink 48 is a weak negative pressure. At this time, when a voltage is applied between the common electrode 50 and the individual electrode 82 for generating a pressure wave, the piezoelectric film 51 is distorted in the thickness direction due to a lateral effect, and the distortion amount of the upper and lower surfaces of the piezoelectric film 51 is reduced. The difference results in a unimorph deformation shown by the phantom line in FIG. Due to this unimorph deformation, a sharp positive pressure is generated in the ink 84, and the meniscus 85 of the ink discharge port 48 becomes convex.

When the voltage application state between the electrodes 50 and 82 is released, the unimorph deformation of the piezoelectric element 82 is released, and the shape of the meniscus 85 of the ink discharge port 48 returns to a concave shape due to the surface tension of the meniscus. The electrode 5
By making the voltage applied between 0 and 82 into a pulse-like voltage, a continuous pressure wave is generated in the ink 48 by rapid repetition of positive pressure and weak negative pressure, and this pressure wave causes the meniscus of the ink ejection port 48 to change. The shape 85 repeats irregularities. The frequency of the pulse voltage is, for example, 1 to 16 k
Hz. When the frequency is 16 kHz, the print dot diameter of the ink droplet ejected from the ink ejection port 48 is, for example, about 40 μm. The frequency is selected in this range because if the frequency exceeds 16 kHz, the meniscus 85
When the position of is not restored, the meniscus 85 rises due to the next pressure wave, and the next ink droplet is ejected in a state where the shape of the meniscus 85 is not stable. Inconveniences such as a failure to obtain an ink droplet speed occur. When the frequency is less than 1 kHz, a problem arises in that the droplet generation rate is low, which is not practical. For this reason, the frequency is chosen between 1 and 16 kHz.

FIG. 7 is a sectional view of a channel when an elastic wave generating means according to still another embodiment of the present invention is a superposed elastic wave generating piezoelectric element 91, and FIG. 8 is a plan view of FIG. FIG. 9 is a cross-sectional view taken along section line IX-IX in FIG. In the present embodiment, portions corresponding to the configuration of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. The superposed elastic wave generation piezoelectric element 91 includes the common electrode 50, the piezoelectric film 51, and the individual electrode 92 for superposed elastic wave generation. The individual electrode 92 for generating a superposed elastic wave is composed of an individual electrode 93 for generating a pressure wave formed in a plane on the piezoelectric film 51 and an individual electrode 9 for generating the pressure wave on the piezoelectric film 51.
Two individual electrodes 94a and 94b for generating a surface acoustic wave are formed closer to the ink discharge port 48 than in 3 and are formed in a comb shape at intervals in the longitudinal direction of the piezoelectric film 51. Further, the individual electrode 93 for generating pressure waves and one individual electrode 94a for generating surface acoustic waves are integrally formed,
One end of the individual electrode 93 for generating a pressure wave is connected to the common electrode 50.

FIG. 10 is a model diagram for explaining the principle of generation of surface acoustic waves, and FIG. 11 is a model diagram for explaining the principle of generation of a fluid flow by surface acoustic waves.
Referring to FIG. 7 as well, when a voltage is applied and released between the electrodes 94a and 94b in the pair of comb electrodes 94a and 94b of the two comb electrodes 94 provided on the piezoelectric film 51, A Rayleigh wave, which is a surface acoustic wave, is generated on the surface of the piezoelectric film 51 by the distortion caused by the lateral effect and the release thereof. The motion of the mass point on the surface of the piezoelectric film 51 by the Rayleigh wave performs an elliptical motion in a plane parallel to the traveling direction of the wave and perpendicular to the surface. Due to this elliptical motion, the Rayleigh wave travels in the direction opposite to the elliptical motion direction of the mass point as shown by the imaginary line in FIG.

A Rayleigh wave is generated on the surface of the piezoelectric film 51,
When the fluid 84 is in contact with the surface, the elliptical motion occurs on the surface of the piezoelectric film 51, and the Rayleigh wave proceeds. Since the ink 84, which is a fluid, tends to stop at the spot, the ink 84 generates an elliptical motion in the opposite direction to cancel the elliptical motion of the surface of the piezoelectric film 51. That is, the ink 84 flows out in the direction opposite to the traveling direction of the Rayleigh wave.

Therefore, when a pulse-like voltage is applied between the comb electrodes 94a and 94b, the comb electrodes 94a and 94b
b, the piezoelectric film 5 due to Rayleigh waves on the surface of the piezoelectric film 51
1 has a portion where the flow of the ink 84 is flowing and a portion where the flow is not generated, that is, a dense portion and a rough portion of the ink 84 are generated in the ink 84, whereby the ink ejection is performed. A compression wave is generated that travels toward the outlet 48. This compression wave is generated by the meniscus 8 of the ink discharge port 48.
5, a minute projection 95 corresponding to the wavelength λ of the Rayleigh wave is formed on the surface. Here, the frequency of the pulse voltage is selected, for example, from 1 to 300 MHz. If it is less than 1 MHz, there is a problem that fine projections are not formed on the meniscus, and if it exceeds 300 MHz, there is a problem that fine projections are not formed. Therefore, 1-3
00 MHz is selected. Where the frequency is 300 MHz
At this time, since the sound velocity in the ink 84 is 1500 m / s, a minute projection 95 of 5 μm is formed on the meniscus 85 of the ink discharge port 48.

Therefore, in order to generate a superimposed elastic wave using the piezoelectric element 91, the frequency is 1 to 16 kHz between the common electrode 50 and the individual electrode 93 for pressure wave generation.
And a pulse-like voltage having a frequency of 1 to 300 MHz is applied between the comb-like electrodes 94. As a result, the pressure wave and the surface acoustic wave are
The meniscus 85 of the ink ejection port 48 has a convex ridge having a period based on the frequency of the pressure wave over the entire surface of the meniscus 85 due to the pressure wave and a period having a period based on the frequency of the surface acoustic wave on the meniscus 85 due to the surface acoustic wave. A minute projection 95 is generated.

FIG. 12 is a cross-sectional view for explaining ink droplet generation and flying operations when the elastic wave generating means is the superposed elastic wave generating piezoelectric element 91. When an applied voltage Vb of the recording power supply 64 is applied between the counter electrode 62 and the common electrode 50, an electric field is generated between the electrodes 50 and 62, and the intermediate transfer belt 63 disposed in the electric field is dielectrically polarized, and the ink is discharged. One surface of the intermediate transfer belt 63 facing the outlet 48 is positively charged. When the channel 45 is selected according to the recording information, the channel selection voltage Vc, which is a pulse-like voltage, is applied between the common electrode 50 and the individual electrode 92 for generating the superposed elastic wave, and the ink is discharged from the common electrode 50 and the common electrode 50. It is applied between the channel selecting electrode portion 96 near the outlet 48. At this time, the pulse waveform of the channel selection voltage Vc is a waveform in which a pulse waveform for generating an elastic wave is superimposed. The details of the superimposed waveform will be described later.

When the voltage Vc is applied between the electrodes 50 and 92, the piezoelectric element 91 generates a superposed elastic wave,
By propagating the ink 84, a convex protrusion having a period based on the frequency of the pressure wave due to the pressure wave and a minute projection 95 having a period based on the frequency of the surface acoustic wave due to the surface acoustic wave are formed on the meniscus 85 of the ink ejection port 48. . When the entire surface of the meniscus 85 has a convex shape and the minute protrusions 95 are formed on the surface thereof, the electric charges are concentrated on the minute protrusions 95, and the minute protrusions 95 are negatively charged, and the minute protrusions protruding from the minute protrusions 95 are formed. The droplet flies by electrostatic attraction and adheres to a desired position on the intermediate transfer belt 63.

When the entire surface of the meniscus 85 is concave and the minute projections 95 are formed on the surface thereof, the electric field does not concentrate on the minute projections 95. This is the electrode portion 96
Since the electrostatic attraction force acts on the ink 84 near the ink ejection port 48 closest to the small projection 95, only a small electrostatic attraction force acts on the minute projections 95. In addition, since the pulling motion on the entire surface of the meniscus 85 acts on the ink 84 as a force in the direction opposite to the ink droplet ejection direction, the ink droplet
Does not discharge from

FIG. 13 shows a piezoelectric element 91 for generating a superposed elastic wave.
FIG. 9 is a diagram illustrating a relationship between the frequency of surface acoustic waves and the print dot diameter of ink droplets when using. For high-definition recording, one method is to reduce the print dot diameter. Therefore, when the frequency of the surface acoustic wave is increased, FIG.
As shown in FIG. 3, at 300 MHz, the print dot diameter of the ink droplet is minimum, and its size is about 10 μm. Even if a surface acoustic wave having a frequency exceeding 300 MHz is generated, an ink droplet having a diameter of 10 μm or less cannot be stably generated. ~ 300
MHz. Therefore, by adopting such a method, fine ink droplets can be generated, and high-definition recording can be performed. Here, various conditions for obtaining the result of FIG. 13 are as follows: the recording voltage Vb is 1.5 kV, the distance between the ink ejection port and the counter electrode is 400 μm, the pressure wave frequency is 2 kHz, the ink viscosity is 10 cps, and the ink surface tension is 30 dyn / cm.

In the above-described embodiment of the present invention, the generation and flying operation of the ink droplet by the superposed elastic wave generating piezoelectric element 91 have been described.
Also, in the case of the surface acoustic wave generating piezoelectric element 44, an elastic wave is generated to generate a bulge or a minute protrusion of the meniscus 85, and the generation and flying of the ink droplet can be performed by the electrostatic attraction force from the tip. .

Here, the recording voltage Vb is about 1.5 kV for the superposed elastic wave and about 2 kV for the pressure wave when the superposed elastic wave is applied and when the pressure wave is applied as the elastic wave. This difference is due to the difference in the meniscus shape in each case. In other words, in the case of a pressure wave, the entire surface of the meniscus is protruded into a convex shape, and the electric field is concentrated near the vertex to eject ink droplets. Since the ink droplets are ejected from the minute protrusions as described above, the distance between the leading end of the ink and the intermediate transfer belt 63 is reduced by the minute protrusions.

Further, the electrostatic attraction increases in inverse proportion to the square of the distance between the positive and negative charges, so that the voltage required to form an electric field can be reduced. Therefore, the voltage for generating the electrostatic attraction necessary to generate and fly the ink droplet can be reduced.

FIG. 14 is a flowchart for explaining the procedure for forming the piezoelectric element, and FIG. 15 is a cross-sectional view for explaining the procedure for forming the piezoelectric element. Here, the procedure for forming the superposed elastic wave generating piezoelectric element 91 will be described. The process moves from step n1 to step n2. In step n2,
After the surface of the silicon substrate 43 shown in FIG. 15 (1) is subjected to nitriding treatment to increase the alkali resistance, a common electrode is provided on the surface of the silicon substrate 43 at intervals as shown in FIG. 15 (2). A plurality of titanium electrodes 50 are formed by sputtering. Proceeding to step n3, the piezoelectric film 5
1 is formed. After a photoresist is applied on each titanium electrode 50, pattern exposure and development are performed, the film formation region D2 of the PZT (lead zirconate titanate) thick film 51 which is a piezoelectric film is removed by etching, and FIG. As shown in FIG. 1), the film formation region D2 has a thickness of 1 by a hydrothermal method.
A PZT thick film 51 of 0 μm is formed. First, P
bNO ₃ aqueous solution 200 mmol / l, ZrOCl ₂ aqueous solution ₂₀₀ mmol / l and KOH aqueous solution 2 mol / l
The silicon substrate 43 is immersed in a mixed solution of
For 10 hours to form a crystal nucleus. Next, in order to grow the crystal, a Pb (NO ₃ ) ₂ aqueous solution 200 mmol / l, a ZrOCl ₂ aqueous solution 200 m
The silicon substrate 43 on which the crystal nuclei are formed is immersed in a mixed solution of 200 mol / l of a TiCl ₄ aqueous solution and 2 mol / l of a KOH aqueous solution, and subjected to a hydrothermal treatment at a temperature of 120 ° C. for 48 hours. Then, ultrasonic cleaning is performed in an acetic acid aqueous solution.

PZT thick film 51 formed by hydrothermal method
In the case of PZT, the crystal structure of PZT is determined by the influence of Ti atoms in titanium oxide (TiO ₂ ) as a base. That is,
Depending on the position of the Ti atom in the crystal structure, the polarization direction is determined in the direction perpendicular to the silicon substrate 43, and the ceramic PZ
There is no need for the polarization treatment required for T.

In step n4, individual electrodes 92 for generating superposed elastic waves are formed. The formation of the individual electrodes 92 is performed by electroless plating of Ni. That is, the surface of the PZT thick film 51 is immersed in a plating bath to form a 5 μm Ni film on the entire surface. Thereafter, a photoresist is spin-coated on the plating surface, the individual electrodes 92 are subjected to pattern exposure and development, and then unnecessary portions are removed by etching to form the individual electrodes 92. The process proceeds from step n4 to step n5, where the piezoelectric element 91 is formed.

In step n4, by changing the pattern of the individual electrodes to the pattern of the individual electrodes for generating pressure waves or surface acoustic waves, the piezoelectric elements 81 and 84 for generating pressure waves or surface acoustic waves can be easily formed. Can be formed.

In the above embodiment of the present invention, the electroless plating of Ni is used for forming the individual electrodes.
After a film is formed over the entire surface by vacuum evaporation, a method of forming an electrode pattern by photolithography may be used.

FIG. 16 is an electric circuit diagram showing an example of a channel selection voltage generation circuit 101 for superposing a pulse wave of an elastic wave generation voltage on a pulse waveform of a channel selection voltage Vc.
FIG. 17 is a pulse waveform diagram of the channel selection voltage Vc.

The channel selection voltage generating circuit 101 is formed by connecting three transistors Tr1, Tr2, Tr3, a Zener diode ZD and a resistor R. The transistor Tr1 is an NPN transistor, and the transistors Tr2 and Tr3 are PNP transistors. The transistors Tr1 and Tr2 are connected in series. A resistor R is connected in parallel with the transistor Tr1, and a Zener diode ZD is connected between the resistor R and the transistor Tr1 in the reverse voltage direction. The transistor Tr3 is connected to the Zener diode ZD in parallel. And 250 between the collectors of the transistors Tr1 and Tr2.
A voltage of V is applied.

When an input signal s1 as a channel selection signal is input to the bases of transistors Tr1 and Tr2,
Tr1 is OFF and Tr2 is ON. The output B at this time is -250V. The Zener voltage of the Zener diode ZD is set to 50 V, and a voltage of 250 V is applied between BD. Then, Zener diode ZD causes Zener breakdown, and the voltage between B and C becomes 50
Since it is held at V, the output becomes -200V. When the application state of the base voltage by the input signal s1 is released, T
r1 is ON, Tr2 is OFF, and the output B is 0V.

When the input signal s2, which is a signal for generating an elastic wave, is not input to the base of the transistor Tr3, the waveform of the channel selection voltage Vc, which is the output waveform, is as shown in FIG.
Is similar to the input signal s1.

When the input signal s1 is inputted to the bases of the transistors Tr1 and Tr2 and the comb-shaped input signal s2 is inputted to the base of the transistor Tr3, only one cycle of the comb-shaped waveform is considered.
When no voltage is applied to the base of r3, A '
The voltage between -B remains at 200V. On the other hand, when a voltage is applied to the base of the transistor Tr3,
The transistor Tr3 becomes conductive between the emitter and collector, and rises by the Zener voltage, and the voltage between A ′ and B becomes 250V. Therefore, since the above-described voltage change occurs by the frequency of the input signal s2, the waveform of the channel selection voltage Vc, which is the output waveform, is similar to the waveform in which the input signal s1 and the input signal s2 are superimposed as shown in FIG. Waveform.

Therefore, since the channel selection voltage Vc is applied between the common electrode and the individual electrode, when a channel is selected, an elastic wave can be generated by the piezoelectric element.

[0073]

As described above, according to the present invention, an elastic wave generating means for applying an elastic wave to the ink in each ink passage is provided in each ink passage individually for each ink passage. An ink interface can be individually formed in a convex shape at the ink discharge port of the passage, and a minute droplet of ink can be generated and fly for each ink passage. Can be achieved.

Further, since the common electrode includes a channel selection electrode portion and an elastic wave generation electrode portion, the number of wires per ink passage is smaller than when a circuit is formed by dividing the two electrode portions. Thus, the cost of the circuit can be reduced.

Further, since the elastic wave travels toward the ink discharge port and discharges an ink droplet from the ink discharge port,
Ink droplets can be ejected from the selected ink passage to land at a desired position regardless of disturbance such as temperature, and the stability and reliability of the ink droplet landing point can be improved.

According to the present invention, since the elastic wave generating means is a piezoelectric element for generating a pressure wave having a frequency of 1 to 16 kHz to the ink in each ink passage, the generated pressure wave is generated at the ink discharge port. The shape of the ink interface can be made to protrude in a convex shape toward the ink droplet deposition medium at a cycle based on the cycle of the pressure wave. Therefore, when the ink interface becomes convex, the ink droplet can be easily caused to fly from the vertex by electrostatic attraction.

According to the present invention, the elastic wave generating means is a piezoelectric element for generating a surface acoustic wave which gives a surface acoustic wave having a frequency of 1 to 300 MHz traveling toward the ink interface to the ink in each ink passage. The generated surface acoustic wave generates a compression wave corresponding to the wavelength of the surface acoustic wave in the ink, forms minute protrusions at the ink interface of the ink discharge port, and easily causes the ink droplets to fly by electrostatic attraction. be able to.

According to the present invention, since the elastic wave generating means is a piezoelectric element for generating a superposed elastic wave which superimposes a pressure wave and a surface acoustic wave on the ink in each ink passage, the generated superposed elastic wave is generated. Has a convex shape at the ink interface of the ink ejection port with a cycle based on the frequency of the pressure wave, and forms fine protrusions on the surface with a cycle based on the frequency of the surface acoustic wave, so that ink droplets can easily fly by electrostatic attraction Can be done.
Therefore, since the distance between the tip of the ink portion and the ink droplet-adhering medium is shorter than that in the case of the pressure wave, the voltage that generates the electrostatic attraction required for generating and flying the ink droplets should be reduced. Can be.

According to the present invention, the common electrode includes a channel selecting electrode portion near the ink ejection port and an electrode portion for forming an electric field between the individual electrodes for generating an elastic wave on the piezoelectric film. Therefore, the number of wirings can be reduced as compared with the case where a circuit is formed by dividing the electrode portion, and the cost of the circuit can be reduced.

According to the present invention, the individual electrodes formed on the piezoelectric film are planar, and a voltage is applied between the common electrode and the individual electrodes. As a result, a pressure wave is generated in the ink due to a rapid repetition of a positive pressure and a weak negative pressure, and the entire surface of the ink interface can be formed in a convex shape with a period based on the frequency of the pressure wave. The ink can easily fly by electrostatic attraction.

According to the present invention, the two layers formed on the piezoelectric film
The two individual electrodes are formed in a comb shape at intervals in the longitudinal direction of the piezoelectric film, and a voltage is applied between the individual electrodes, so that a surface acoustic wave is generated in the piezoelectric element, and this is generated. The compression wave caused by the flow of the ink propagates in the ink, and forms minute projections at the ink interface corresponding to the wavelength of the surface acoustic wave with a period based on the frequency of the surface acoustic wave, and easily flies by electrostatic attraction. be able to.

According to the present invention, since a voltage is applied between the common electrode and the planar individual electrode and between the individual comb-shaped individual electrodes, the piezoelectric element is subjected to unimorph deformation in the planar electrode portion. The generated pressure wave and the surface elastic wave at the comb-shaped electrode portion can be superimposed and generated, and the entire ink interface of the ink ejection port is formed in a convex shape at intervals based on the frequency of the pressure wave, and is formed on the surface thereof. The minute protrusions can be formed at a cycle based on the frequency of the surface acoustic wave, and the minute droplets of the ink can be easily ejected from the minute protrusions by electrostatic attraction.

According to the present invention, since the common electrode shares the electrodes facing the individual electrodes, the number of wires per channel can be reduced. Further, since the channel selection voltage is applied between the electrodes, an elastic wave can be generated by the piezoelectric element when a channel is selected.

According to the present invention, since the ink droplet adhering surface is arranged close to the ink ejection port of the ink jet head, the voltage required for generating and flying the ink droplet can be reduced. In addition, the ink jet recording apparatus adheres minute droplets of ink to the ink droplet adhering surface of the ink droplet adhering medium and transfers the ink droplet to the recording area of the recording paper via the ink droplet adhering medium for recording. The resolution of a printed or printed image can be increased, and a high quality printed or printed image can be obtained by stabilizing an ink droplet landing point caused by ejection of an ink droplet from an ink passage of a selected inkjet head. .

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an inkjet head 41 according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating a configuration of a recording unit 61 of the inkjet recording apparatus.

FIG. 3 is a configuration diagram of a color serial printer 71 including the inkjet head 41 of the present invention.

FIG. 4 shows a channel 45 when an elastic wave generating means according to another embodiment of the present invention is a pressure wave generating piezoelectric element 81;
FIG.

FIG. 5 is a cross-sectional view taken along the line VV of FIG. 4;

FIG. 6 is a sectional view taken along section line VI-VI in FIG. 4;

FIG. 7 is a cross-sectional view of a channel 45 when an elastic wave generating means according to still another embodiment of the present invention is a superposed elastic wave generating piezoelectric element 91;

FIG. 8 is a plan view of FIG. 7;

FIG. 9 is a cross-sectional view as viewed from the section line IX-IX of FIG. 8;

FIG. 10 is a model diagram for explaining the principle of generation of surface acoustic waves.

FIG. 11 is a model diagram for explaining the principle of generation of a fluid flow by surface acoustic waves.

FIG. 12 is a cross-sectional view for explaining ink droplet generation and flying operations when the elastic wave generating means is a superposed elastic wave generating piezoelectric element 91.

FIG. 13 is a diagram showing the relationship between the frequency of surface acoustic waves and the print dot diameter of ink droplets.

FIG. 14 is a flowchart for explaining a procedure for forming a piezoelectric element.

FIG. 15 is a cross-sectional view for explaining a procedure for forming a piezoelectric element.

FIG. 16 is an electric circuit diagram showing an example of a channel selection voltage generation circuit 101 for superposing a pulse waveform of an elastic wave generation voltage on a pulse waveform of a channel selection voltage Vc.

FIG. 17 is a pulse waveform diagram of a channel selection voltage Vc.

FIG. 18 is a front view showing a configuration of an ink jet recording head 1 disclosed in Japanese Patent Publication No. Sho 58-49189.

FIG. 19 is a diagram showing a configuration of an ink jet recording apparatus 11 disclosed in Japanese Patent Application Laid-Open No. 3-5150.

FIG. 20 is a diagram showing a configuration of an ink jet printer 21 disclosed in Japanese Patent Application Laid-Open No. 2-198853.

21 is a perspective view of a part of FIG.

FIG. 22 is a configuration diagram showing a traveling state of an ultrasonic wave.

FIG. 23 is a diagram showing a raised portion of ink generated by applying a pulsed voltage to the ultrasonic exciter.

FIG. 24 is a diagram showing a ridge 32 of ink generated by applying a sinusoidal voltage to the ultrasonic exciter 30.

[Explanation of symbols]

 41 Inkjet head 42 Cover plate 43 Substrate 44 Piezoelectric element for generating surface acoustic waves 45 Channel 46 Ink storing section 48 Ink ejection port 50 Common electrode 51 Piezoelectric film 52 Individual electrode 62 Counter electrode 63 Intermediate transfer belt 64 Recording power supply 65 Channel selection means 73 Transfer roller 74 Recording paper 75 Platen 77 Ink droplet adhering surface 81 Piezoelectric element for generating pressure wave 82 Individual electrode for generating pressure wave 84 Ink 85 Meniscus 91 Piezoelectric element for generating superimposed elastic wave 92 Individual electrode for generating superposed elastic wave 95 Micro Protrusion

Claims (10)

[Claims] A plurality of ink passages each having an ink discharge port that opens to face an ink droplet deposition medium are separately formed, and each ink passage communicates in common with a storage section in which ink is stored. Ink is guided to the ink passage, and a channel selection voltage is applied between the ink droplet application medium and the ink interface facing the ink droplet application medium from the ink ejection port, and the ink droplet is applied from the ink interface to the ink droplet application medium. An ink jet head which flies by an electrostatic attraction force, wherein an elastic wave generating means for applying an elastic wave to the ink in each ink passage is individually provided in each ink passage. head. 2. An ink jet head according to claim 1, wherein said elastic wave generating means is a piezoelectric element for generating a pressure wave having a frequency of 1 to 16 kHz to ink in each ink passage. 3. An elastic wave generating means for applying a frequency of 1 to 3 to ink in each ink passage toward an ink interface.
2. The ink jet head according to claim 1, which is a piezoelectric element for generating a surface acoustic wave that gives a surface acoustic wave of 00 MHz. 4. The elastic wave generating means superimposes a pressure wave having a frequency of 1 to 16 kHz and a surface acoustic wave having a frequency of 1 to 300 MHz traveling toward an ink interface on ink in each ink passage. 2. The ink jet head according to claim 1, wherein the ink jet head is a piezoelectric element for generating a superposed elastic wave. 5. The piezoelectric element is formed in a common electrode formed on one surface of the substrate facing the ink passage, and in a region near the ink discharge port on the common electrode except for a channel selection electrode portion. The inkjet head according to any one of claims 2 to 4, comprising a piezoelectric film and an individual electrode formed on the piezoelectric film. 6. The piezoelectric element is formed in a common electrode formed on one surface of the substrate facing the ink passage, and in a region near the ink discharge port on the common electrode except for a channel selection electrode portion. 3. The ink jet head according to claim 2, further comprising: a piezoelectric film; and individual electrodes for generating pressure waves formed on the piezoelectric film in a planar shape. 7. The piezoelectric element is formed in a common electrode formed on one surface of the substrate facing the ink passage, and in a region near the ink ejection port on the common electrode except for a channel selection electrode portion. 4. A piezoelectric film comprising: a piezoelectric film; and two individual electrodes for generating surface acoustic waves, each of which is formed in a comb-like shape at intervals in the longitudinal direction of the piezoelectric film. The inkjet head according to the above. 8. The piezoelectric element is formed in a common electrode formed on one surface of the substrate facing the ink passage, and in a region near the ink discharge port on the common electrode except for a channel selection electrode portion. A piezoelectric film, an individual electrode for pressure wave generation formed in a planar shape on the piezoelectric film, and an ink discharge port closer to the ink ejection port than the individual electrode for pressure wave generation on the piezoelectric film, in the longitudinal direction of the piezoelectric film. 5. The ink jet head according to claim 4, comprising two comb-shaped individual electrodes for generating surface acoustic waves, each of which is formed in a comb-tooth shape at a distance from each other. 9. An end of an individual electrode is connected to the common electrode, and an interval between the electrodes is used to generate an elastic wave for causing an ink droplet to fly from an ink interface to an ink droplet applying medium by electrostatic attraction. 9. The ink jet head according to claim 6, wherein a channel selection voltage superimposed with the elastic wave generation voltage is applied. 10. An ink droplet application medium, and a plurality of ink passages each having an ink ejection port opening toward the ink droplet application surface of the ink droplet application medium are formed by being individually partitioned, and each ink passage stores ink. Ink is guided to each ink passage in common communication with the storage portion to be formed, and elastic wave generating means for applying an elastic wave to the ink in each ink passage is provided in each ink passage individually for each ink passage. The elastic wave generating means applies an elastic wave to the ink in the ink passage while applying a channel selection voltage between the ink droplet deposition medium and the ink interface of the ink ejection port to generate an electrostatic attraction force, An ink jet head that causes ink droplets to fly from the interface to the ink droplet adhering surface of the ink droplet adhering medium; Recording paper feeding means for intermittently moving the recording paper at a predetermined feed speed so as to face the ink droplet adhesion surface of the adhesion medium and sequentially updating the recording area; When the area where the ink droplets adhere to the surface is arranged in the transfer area, the ink-adhered medium is pressed in a direction approaching the recording area of the recording paper, and the area where the ink droplets adhere to the recording area of the recording paper. An ink-jet recording apparatus, comprising: a transfer unit for transferring by contact.