JP2000158645A - Ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the responsiveness of ink with respect to an actuator in terms of an ink jet head that ejects ink in a pressurizing chamber as ink drops from a nozzle by displacing the actuator having a piezoelectric element by applying a voltage to the piezoelectric element. SOLUTION: This ink jet head comprises a thin actuator 30. A pressurizing chamber 12 is formed such that the length thereof in the longitudinal direction is shorter than a length of a common ink chamber 11 in the same direction. The common ink chamber 11 is demarcated to be formed by a rear plate 24 and a rear side face of a main plate 23. A recess section 21 for the pressurizing chamber is formed on the front side face of the main plate 23 and the pressurizing chamber 12 is demarcated to be formed by the recess section 21 and a diaphragm 26. A nozzle plate 25 is provided to the front side face of the main plate 23. The diaphragm 26 is provided to the front side face of the nozzle plate 25 and a piezoelectric element 27 and an individual electrode 28 are provided to the front side face of the diaphragm 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ink jet head used for an ink jet printer.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Unexamined Patent Application Publication No.
As disclosed in Japanese Patent Laid-Open No. 4 (1999) -104, there is known an ink jet head that performs recording by utilizing a piezoelectric effect of a piezoelectric element. The structure of the ink jet head disclosed in the above publication will be described with reference to FIG.

A plurality of pressure chambers 101 to which ink is supplied and a common ink chamber 102 communicated with the plurality of pressure chambers 101 through an ink supply path 105 are formed inside the ink jet head. . A nozzle 103 is formed on the front side (the lower side in FIG. 11) of the ink jet head.
Are connected through. The back side of each pressure chamber 101 (FIG. 11)
Is defined by the diaphragm 108. A reinforcing plate 109 is stacked on the back side of the diaphragm 108, and a common electrode 110 (lower electrode) is provided on the back side of the reinforcing plate 109. The piezoelectric element 106 is provided on the back side of the common electrode 110. On the back surface of the piezoelectric element 106, an individual electrode 111 (upper electrode) is provided.

The horizontal cross-sectional shape of the pressure chamber 101 is formed in an elongated strip shape. The plurality of pressure chambers 101 are arranged so as to be aligned in a direction perpendicular to the longitudinal direction of the pressure chambers (the L1 direction shown in FIG. 11).

[0005]

However, in the conventional ink jet head, the thickness of the actuator 107 including the vibration plate 108, the common electrode 110, the piezoelectric element 106, and the individual electrode 111 is large, and a sufficient amount of deflection displacement is required. Therefore, it was necessary to ensure that the length of the actuator 107 in the longitudinal direction was sufficiently large. Accordingly, the longitudinal length of the pressure chamber 101 was also large. As apparent from FIG. 11, the length of the pressure chamber 101 in the longitudinal direction (the L1 direction in the drawing) was longer than the length of the common ink chamber 102 in that direction. Therefore, the volume of the pressure chamber 101 was large, and it was difficult to say that the ink responsiveness in the pressure chamber 101 was sufficiently high.

Further, since the actuator 107 is provided on the back side of the head main body and the nozzle 103 is formed on the front side of the head main body, there is a structural limitation on improving the ink responsiveness. That is, the actuator
Pressure chamber 101 and common ink chamber 102 between 107 and nozzle 103
, It takes some time before the pressure applied by the actuator 107 is transmitted to the ink near the nozzle 103.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and an object of the present invention is to improve the responsiveness of ink to an actuator by reducing the size of a pressure chamber.

[0008]

In order to achieve the above object, the present invention reduces the length of the pressure chamber in the longitudinal direction to be shorter than the length of the common ink chamber in the same direction, thereby reducing the size of the pressure chamber. It was decided to.

Specifically, the present invention provides a common ink chamber,
A plurality of pressure chambers communicating with the common ink chamber, and an actuator having a piezoelectric element; applying a voltage to the piezoelectric element to displace the actuator to apply pressure to ink in the pressure chamber; In an inkjet head that ejects ink droplets from nozzles by pressure,
The length of the pressure chamber in the longitudinal direction is shorter than the length of the common ink chamber in the same direction as the length of the pressure chamber.

According to the above, the length of the pressure chamber in the longitudinal direction is shortened, so that the pressure chamber is downsized. Therefore, the responsiveness of ink droplets in the pressure chamber is improved, and the performance of printing and the like is improved.

The above-mentioned ink jet head is, for example, shown in FIG.
As shown in the figure, a back side, a back side opposed to the back plate at a predetermined interval so as to form a common ink chamber between the back plate and a plurality of pressure chamber recesses are formed. A main body plate having a plurality of ink supply passages connecting the common ink chamber and the respective pressure chamber recesses, and a plurality of nozzles corresponding to the respective pressure chamber recesses penetrating therethrough. And a nozzle plate provided on the front side of the main body plate so that each nozzle covers a part of each pressure chamber recess.
The actuator includes a vibrating plate that is provided on the front surface of the nozzle plate and covers each pressure chamber recess of the main body plate so as to form a pressure chamber together with each of the pressure chamber recesses. May be provided on the front surface of the diaphragm.

In this specification, the side on which the nozzle is provided is referred to as the front side.

According to the above, since the nozzle plate is provided so as to cover the recess for the pressure chamber, the nozzle and the pressure chamber are adjacent to each other, and the ink discharge path from the pressure chamber to the nozzle opening becomes very short. As a result, the responsiveness of the ink is improved, and the ejection of the ink droplet is performed smoothly. Further, since the common ink chamber is defined between the main body plate and the back plate, it is easy to form the common ink chamber large.

The front surface of the actuator may be covered with a water-repellent coating material.

According to the above, the front surface of the actuator has water repellency, and the adhesion of ink is prevented. Therefore, even when the actuator and the nozzle are located on the same surface side, the ejection of the ink droplet is performed favorably. In addition, the actuator is protected, and deterioration of characteristics due to adhesion of foreign matter or the like is prevented.

The above-mentioned ink jet head has a nozzle plate having nozzles formed thereon, for example, as shown in FIG.
An actuator comprising: a main body plate provided on the back surface side of the nozzle plate, having a plurality of pressure chamber recesses formed on the back side surface, and an ink ejection path connecting the pressure chamber recesses and the nozzles formed therethrough; A diaphragm provided on the back side of the main body plate so that an ink supply port is formed at a position corresponding to each of the pressure chamber recesses so as to define each pressure chamber together with each pressure chamber recess. The piezoelectric element of the actuator is provided on a back side surface of the diaphragm, has a drive circuit for applying a drive voltage to the piezoelectric element, and has a common ink chamber recess formed on a front side surface of the common ink chamber. And a substrate provided on the back side of the actuator.

According to the above, since the nozzle plate is located near the pressure chamber, the ink discharge path is shortened. Also, the distance between the actuator and the nozzle is reduced. As a result, the responsiveness of the ink is improved, and the ejection of the ink droplet is performed smoothly. In addition, since the substrate provided with the drive circuit forms the partition wall of the common ink chamber, the members can be integrated and the cost can be reduced.

The ink jet head is provided between the main body plate and the vibration plate, and has a plurality of central openings corresponding to the center of each pressure chamber recess and a plurality of ink openings corresponding to the ink supply ports of the vibration plate. An ink supply port is provided between the actuator and the substrate so as to define a common ink chamber between the intermediate plate formed through and the substrate, and corresponds to each of the central openings on a surface facing the actuator. And a partition plate in which openings are formed at positions corresponding to the ink supply ports of the vibration plate and the intermediate plate.

According to the above, since the partition plate is provided between the actuator and the substrate, the piezoelectric element of the actuator is prevented from coming into contact with the ink in the common ink chamber. In addition, since the concave portion is formed at a position corresponding to each of the central openings of the partition plate, the actuator deforms in the concave portion, and the deformation is facilitated. Therefore, the operation of the actuator is performed smoothly.

As shown in FIG. 8, for example, the ink jet head includes a main body plate having a front surface on which a plurality of pressure chamber recesses are formed, and an actuator is provided at a position corresponding to each of the pressure chamber recesses. A diaphragm provided on the back side of the main body plate so as to form an ink supply port therethrough so as to define each pressure chamber together with each of the pressure chamber recesses; A drive circuit for applying a drive voltage to the piezoelectric element is provided on the side surface, and is provided on the front side of the actuator and defines a common ink chamber and a front side surface on which a plurality of nozzles corresponding to each pressure chamber are formed. A back side surface in which a common ink chamber concave portion is formed, and a substrate in which an ink discharge path connected to each nozzle is formed.

According to the above, the distance between the actuator and the nozzle is shortened, and the responsiveness of the ink is improved.
Further, since the substrate provided with the drive circuit forms the partition wall and the nozzle of the common ink chamber, the members can be centralized,
Costs are reduced.

The ink jet head is provided between the main body plate and the vibration plate, and has a plurality of central openings corresponding to the center of each pressure chamber recess and a plurality of center openings corresponding to the end of each pressure chamber recess. An intermediate plate having an ink supply port and an ink discharge port formed therethrough, and a substrate provided between the actuator and the substrate so as to define a common ink chamber between the substrate and the above-described surface on the surface facing the actuator. A recess may be formed at a position corresponding to the central opening, and a partition plate may be provided in which the ink supply port and the ink discharge port corresponding to the ink supply port and the ink discharge port are formed.

According to the above, since the partition plate is provided between the actuator and the substrate, the piezoelectric element of the actuator is prevented from contacting the ink in the common ink chamber. In addition, since the concave portion is formed at a position corresponding to each of the central openings of the partition plate, the actuator deforms in the concave portion, and the deformation is facilitated. Therefore, the operation of the actuator is performed smoothly.

As shown in FIG. 3, for example, the ink jet head includes a plurality of pressure chamber rows in the main scanning direction in which pressure chambers are aligned in the sub-scanning direction. The pressure chambers may be arranged in a staggered manner at positions corresponding to adjacent pressure chambers in an adjacent pressure chamber row.

According to the above, the pressure chambers of each pressure chamber row are:
Since they are arranged in a staggered manner so as to be positioned at positions corresponding to adjacent pressure chambers in an adjacent pressure chamber row, the dot density is improved and the head is reduced in size.

[0026]

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

<First Embodiment> As shown in FIG. 1, an ink jet printer 6 includes an ink jet head 1 for performing recording by utilizing the piezoelectric effect of a piezoelectric element. Is recorded on the recording medium 4 by landing on the recording medium 4. The inkjet head 1 is mounted on a carriage 2 that reciprocates along a carriage shaft 3 and is configured to reciprocate in a main scanning direction X parallel to the carriage shaft 3.
The recording medium 4 is transported in the sub-scanning direction Y by the rollers 5.

The ink jet head 1 has a head body 10 in which a common ink chamber 11, a plurality of pressure chambers 12, and a plurality of nozzle openings (not shown in FIG. 2) are formed as shown in FIG. And a driver IC. The plurality of pressure chambers 12 are arranged in eight rows in the main scanning direction X,
It is arranged in zigzag. The connection terminals 15 connected to the individual electrodes of the actuator 30 are arranged along the sub scanning direction Y on both sides of the head main body 10 in the main scanning direction X. The connection terminal 15 is connected to a driver IC (not shown) by wire bonding or the like.
Is transmitted to the individual electrodes.

Next, referring to FIG.
The arrangement pattern of the pressure chambers 12 and the like will be described. FIG. 3 shows four rows on the left side in FIG. 1 among the eight rows of pressure chambers. Each of the pressure chambers 12 is formed such that its major axis L is orthogonal to the row direction Y. In addition, in the row group of the first row of pressure chambers 12a located at the left end in FIG. 3, the second row of pressure chambers 12b correspond to the first row of adjacent pressure chambers 12a, 12a. Pressure chambers 12b in the second row
The relationship between the arrangement of the pressure chambers 12c in the third row and the arrangement of the pressure chambers 12c in the third row and the arrangement of the pressure chambers 12d in the fourth row are also the same as those in the first row. The relationship between the arrangement of the pressure chambers 12a and the arrangement of the pressure chambers 12b in the second row is the same. That is, the multiple pressure chambers 12 are arranged in a plurality of rows, and are arranged such that the positions of the pressure chambers in the adjacent rows are staggered.

However, the pressure chambers 12 in each row are not aligned on the same straight line orthogonal to the row direction, but are slightly shifted from each other in the row direction. This is to shift the dot positions of each other in the sub-scanning direction.

The pressure chambers 12 on the right side in FIG. 1 as well as the four rows on the left side shown in FIG. 3 are also arranged in a staggered manner. The pressure chambers 12 are shifted from each other in the column direction so as not to be aligned on the same straight line in relation to any of the pressure chambers 12 in the four rows on the left side.

The piezoelectric element 27 and the individual electrode 28 (see FIG. 4) provided separately for each pressure chamber 12 draw the same pattern on the surface of the vibration plate 26 while overlapping each other, and displace the actuator 30. A driving section 35 for causing the driving section 35 is formed. The driving section 35 and the connection terminal 15 are connected by a wiring section 31 formed by extending the individual electrode 28.

The wiring section 31 extending from the drive section 35 of each row of pressure chambers 12b, 12c, 12d located inside the row of the leftmost pressure chambers 12a is connected to the adjacent pressure chamber 12a of another row. , 12b, 12
Passing between c.

That is, in the ink jet head 1, a large number of pressure chambers 12 are arranged in a plurality of rows, and the pressure chambers in adjacent rows are arranged in a staggered manner and arranged so as to be the densest. The head surface side portion of the partition wall separating the adjacent pressure chambers 12, 12 is used as a space for disposing the wiring portion 31. Since three pressure chamber rows are provided inside the adjacent pressure chamber row, three wiring portions 31 pass between adjacent pressure chambers 12a, 12a of the leftmost pressure chamber row. .

The above-described patterns of the piezoelectric elements 27 and the individual electrodes 28 are the same in the four rows of pressure chambers 12 on the right side.

Next, the detailed configuration of the head body 10 will be described. As shown in FIG. 4, the main body plate 23 is opposed to the back plate 24 forming the back side surface of the head main body 10 at a predetermined interval, and is located between the back side surface of the main body plate 23 and the front side surface of the back plate 24. Common ink chamber 11
Are formed. As shown in FIG. 2, the common ink chamber 11 extends over substantially the entire area of the head body 10 in the main scanning direction X, and is formed across a plurality of pressure chambers 12 arranged in the main scanning direction X. In particular, in the present embodiment, the common ink chamber 11 is formed in a single space.

As shown in FIG. 4, a concave portion 21 for a pressure chamber is formed on the front surface of the main body plate 23. In the main body plate 23, an ink supply path 22 continuous with the pressure chamber concave portion 21 is provided.
Penetration is formed from the front side to the back side. The ink supply passage 22 is provided at one end of the pressure chamber concave portion 21 in the major diameter direction, and is formed by two-stage through holes 22a and 22b such that the opening area decreases from the back side to the front side. The through hole 22a located on the back side has a larger diameter than the through hole 22b located on the front side.

On the front side of the main body plate 23, a nozzle plate 25 in which the nozzle 14 is formed is provided so as to cover a part (the right end part in FIG. 3) of the concave portion 21 for the pressure chamber. The nozzle 14 is provided so as to be located on the opposite side of the ink supply path 22 in the long diameter direction of the pressure chamber 12. The nozzle 14 is formed in a tapered nozzle shape such that the cross-sectional area of the flow path decreases in the discharge direction.

A vibration plate 26 is provided on the surface of the nozzle plate 25 so as to cover the recess 21 for the pressure chamber of the main body plate 23. The pressure chamber concave portion 21 and the diaphragm 26 of the main body plate 23 are mainly
Thereby, the pressure chamber 12 is defined. The diaphragm 26 has a nozzle opening at a position corresponding to the nozzle 14 of the nozzle plate 25.
13 are provided. That is, the vibration plate 26 is configured to form a partition wall of the pressure chamber 12 and to allow ink droplets ejected from the nozzle 14 to pass therethrough. The diaphragm 26 is
It is made of Cr or a Cr-based material and also functions as a common electrode for applying a voltage to the following piezoelectric element 27. The thickness of diaphragm 26 is preferably 0.5 μm or more and 5 μm or less, more preferably 1 μm or more and 3 μm or less, and even more preferably 1.5 μm or more and 2.5 μm or less.

The piezoelectric element 27 made of PZT is joined to a portion of the front surface of the diaphragm 26 where the nozzle opening 13 is not provided. As shown in FIG. 3, the portion of the piezoelectric element 27 located at the upper center of the pressure chamber 12 (the portion corresponding to the drive unit 35) is formed in a so-called oval shape whose major axis direction coincides with the main scanning direction. The major axis L of the piezoelectric element 27
It is particularly preferable that the ratio L / S between the diameter and the minor axis S be 1 or more and 3 or less. The thickness of the piezoelectric element 27 is preferably 0.3 μm or more and 8 μm or less, more preferably 1 μm or more and 5 μm or less, and even more preferably 2 μm or more and 3 μm or less.

An individual electrode 28 having substantially the same shape as the piezoelectric element 27 is joined to the front surface of the piezoelectric element 27. The individual electrodes 28
Thickness of 0.05 μm or more and 1 μm or less, for example, 0.1 μm
m of Pt or a Pt-based material.

While the vibration plate 26 is formed over the entire surface of the nozzle plate 25, the piezoelectric elements 27 and the individual electrodes 28 are provided for each of the pressure chambers 12 in pairs. The vibration plate 26, the piezoelectric element 27, and the individual electrode 28 constitute an actuator 30 for applying pressure to the ink in the pressure chamber 12.

The actuator 30 is a thinned actuator. The thickness of the actuator 30 is preferably 0.1 μm or more and 30 μm or less, more preferably 0.1 μm or more and 25 μm or less, and more preferably 0.1 μm or more and 25 μm or less.
1 μm or more and 20 μm or less, more preferably 0.1 μm
m or more and 15 μm or less, more preferably 0.1 μm or more and 10 μm or less, more preferably 0.5 μm or more and 9 μm or less, more preferably 1 μm or more and 8 μm or less, more preferably 2 μm or more and 7 μm or less, more preferably 2 μm or less. Not less than 6 μm, more preferably not more than 3 μm.
The thickness is preferably from μm to 6 μm, more preferably from 4 μm to 6 μm.

The front surface around the nozzle opening 13 of the diaphragm 26 and the front surface of the actuator 30 (more specifically, the surface of the individual electrode 28) are covered with a water-repellent coating material 29 having an insulating property.

Next, a method of manufacturing the head body 10 will be described with reference to FIGS.

First, as shown in FIG. 5A, a substrate 32 for patterning is prepared. As the substrate 32, for example, a substrate having a thickness of 20 mm is used.

Next, as shown in FIG. 5B, a Pt film 33 for an individual electrode is formed on the surface of the substrate 32. The formation is performed by, for example, sputtering. The thickness of the Pt film 33 is, for example, 0.1 μm.

Next, as shown in FIG. 5C, a PZT film 34 for a piezoelectric element is formed on the surface of the Pt film 33. The formation is performed by, for example, sputtering. PZT film
The film thickness of 34 is, for example, 2-3 μm.

Next, as shown in FIG.
Divided patterning is performed on the film 33 and the PZT film 34.
This is a step of forming a pattern of the piezoelectric elements 27 and the individual electrodes 28. This patterning is performed by, for example, chemical etching or ion milling. After the etching, the surface is flattened.

Next, as shown in FIG. 5E, plastic coating is performed. This is a step of filling the portion removed by the patterning with an insulating material (plastic) 36 to insulate the individual electrodes 28 from each other. As this plastic, for example, polyimide is used.

Next, as shown in FIG. 5F, a vibration plate 26 is formed on the surface of the piezoelectric element 27 and the insulating material 36. This formation is performed by, for example, sputtering of Cr. The thickness of the diaphragm 26 is, for example, 2 μm.

Next, as shown in FIG. 5G, a nozzle plate 25 made of plastic is formed on the surface of the vibration plate 26. This formation is performed by, for example, excimer laser processing. As the plastic, for example, polyimide is used. The thickness of the nozzle plate 25 is, for example, 25 μm.

Next, as shown in FIG. 5 (h), the main body plate 23 in which the pressure chamber recess 21 and the ink supply passage 22 are formed is joined to the surface of the nozzle plate 25. This joining is performed using, for example, a thermosetting adhesive.

After this joining step, the back plate 24 is joined to the surface of the main plate 23 via a spacer (not shown) to form the common ink chamber 11 between the main plate 23 and the back plate 24. I do. After that, the substrate 32 is removed.

As described above, according to the first embodiment, since the pressure chamber 12 is miniaturized, the responsiveness of the ink is improved.

Further, since the pressure chamber 12 and the nozzle 14 are adjacent to each other, the flow resistance of the ink at the time of ejection is significantly reduced. For this reason, the ink droplets are smoothly ejected, and printing such as printing is preferably performed.

The common ink chamber 11 is provided between the main body plate 23 and the back plate 24.
Are formed so that the common ink chamber 11 can be made large. Therefore, the pressure fluctuation of the ink in the common ink chamber 11 is small, the mutual interference of the pressure fluctuation between the different pressure chambers 12 is reduced, and the responsiveness of the ink is improved.
Further, since it is not necessary to form a recess for the common ink chamber 11 in the main body plate 23, it is possible to reduce the manufacturing cost.

Since the ink supply passage 22 between the common ink chamber 11 and the pressure chamber 12 is formed to penetrate the main body plate 23 in the front and rear directions,
The ink supply path 22 does not meander. Moreover, the length can be shortened. Accordingly, the flow resistance of the ink from the common ink chamber 11 to the pressure chamber 12 is reduced, and the responsiveness of the ink is improved.

Since the pressure chambers 12 are arranged in a staggered manner, the head density is high. Therefore, high-density ink dots can be formed on the recording medium. Further, the size of the head body can be reduced. Therefore, the head body can be significantly reduced in size, in combination with the effect of reducing the size of the pressure chamber 12 described above.

Since the surface of the actuator 30 is covered with the water-repellent coating material 29, even if the actuator 30 and the nozzle 14 are located on the same side of the head main body 10, the ejected ink adheres to the actuator 30. Is suppressed. Therefore, the ink is ejected favorably. In addition, the actuator 30 is protected from foreign substances such as dust, and deterioration of its characteristics is prevented.

Since the actuator 30 is provided on the surface of the nozzle plate 25, the nozzle plate 25 can be patterned on the surface of the actuator 30 after the formation of the actuator 30 in manufacturing, and the manufacturing cost can be reduced. .

<Second Embodiment> An ink jet head 1 according to a second embodiment is a driver IC having a drive circuit.
The (substrate) 43 is joined to the main body plate 23, and the driver IC 43 also functions as a partition wall for partitioning the common ink chamber 11.

As shown in FIG. 6, a nozzle plate 25 in which the nozzles 14 are formed is provided on the front side surface of the main body plate 23. On the rear side surface of the main body plate 23, a concave portion 21 for a pressure chamber is formed. At a position corresponding to the nozzle 14 on the front side surface of the main body plate 23, an ink discharge path 47 continuous with the pressure chamber concave portion 21 is formed so as to penetrate therethrough. The ink discharge path 47 is formed in a tapered shape from the back side to the front side, and the opening on the front side is a nozzle.
The opening area is larger than the back end of 14.

On the back side of the main body plate 23, an intermediate plate 40 having a central opening 39 slightly smaller than the pressure chamber 12 is provided at a position corresponding to the center of the pressure chamber 12. ing. The intermediate plate 40 has an ink supply port 38 formed continuously therethrough at an end of the pressure chamber 12 opposite to the nozzle 14.

The diaphragm 26 is provided on the back side of the intermediate plate 40. A portion of the vibration plate 26 corresponding to the central opening 39 of the intermediate plate 40 is in contact with the ink in the pressure chamber 12. That is, a part of the diaphragm 26 defines the pressure chamber 12. An opening similar to the ink supply port 38 is formed in the diaphragm 26 at a position corresponding to the ink supply port 38.

A piezoelectric element 27 is formed on the back side of the diaphragm 26. An individual electrode 28 is formed on the back surface of the piezoelectric element 27. Pressure chamber in piezoelectric element 27 and individual electrode 28
The portion corresponding to 12 is a drive unit 35 that performs flexural deformation together with the diaphragm 26 to apply pressure to the ink in the pressure chamber 12. The piezoelectric element 27 and the individual electrode 28 also have openings corresponding to the ink supply ports 38.

On the rear side of the individual electrode 28, a partition plate 41 is provided. The partitioning plate 41 partitions the piezoelectric element 27 and the individual electrode 28 from the common ink chamber 11 so that the piezoelectric element 27 and the individual electrode 28 do not come into contact with the ink. A position corresponding to the central opening 39, that is, a driving unit
A displacement chamber concave portion 46 is formed at a position corresponding to 35.
The displacement chamber concave portion 46 is provided for partitioning a displacement chamber 50 for facilitating the bending deformation of the actuator 30 between the actuator 30 including the drive unit 35. The displacement chamber concave portion 46 is formed at a depth equal to or greater than the maximum displacement of the actuator 30. The rear side surface of the partition plate 41 is formed flush. An opening corresponding to the ink supply port 38 is also formed in the partition plate 41. The ink in the common ink chamber 11 is supplied to the pressure chamber by the opening of the vibration plate 26, the piezoelectric element 27, the individual electrode 28,
An ink supply path 51 leading to 12 is formed.

A driver IC 43 is joined to the rear side surface of the partition plate 41. On the front surface of the driver IC 43, a common ink chamber concave portion 44 is formed. The common ink chamber 11 is defined between the bottom of the common ink chamber concave portion 44 and the rear surface of the partition plate 41. A drive circuit (not shown) is formed on the back surface of the driver IC 43. That is, in the present embodiment, the driver IC 43 not only includes a drive circuit but also functions as a partition wall that partitions the common ink chamber 11.

The patterns of the piezoelectric elements 27 and the individual electrodes 28
This is the same as the first embodiment.

Next, a method for manufacturing the ink-jet head 1 will be described with reference to FIGS.

First, as shown in FIG. 7A, a substrate 32 for patterning is prepared. As the substrate 32, for example, a substrate having a thickness of 20 mm is used.

Next, as shown in FIG. 7B, a Pt film 33 for an individual electrode is formed on the surface of the substrate 32. The formation is performed by, for example, sputtering. The thickness of the Pt film 33 is, for example, 0.1 μm.

Next, as shown in FIG. 7C, a PZT film 34 for a piezoelectric element is formed on the surface of the Pt film 33. The formation is performed by, for example, sputtering. PZT film
The film thickness of 34 is, for example, 2-3 μm.

Next, as shown in FIG.
Divided patterning is performed on the film 33 and the PZT film 34.
This is a step of forming a pattern of the piezoelectric elements 27 and the individual electrodes 28. This patterning is performed by, for example, chemical etching or ion milling. After the etching, the surface is flattened.

Next, as shown in FIG. 7E, plastic coating is performed. This is a step of filling the portion removed by the patterning with an insulating material (plastic) 36 to insulate the individual electrodes. As this plastic, for example, polyimide is used.

Next, as shown in FIG. 7F, a vibration plate 26 is formed on the surface of the piezoelectric element 27 and the insulating material 36. This formation is performed by, for example, sputtering of Cr. The thickness of the diaphragm 26 is, for example, 2 μm.

Next, an intermediate plate 40 is provided on the surface of the diaphragm 26,
As shown in FIG. 7G, the main body plate 23 provided with the nozzle plate 25 is joined to the surface of the intermediate plate 40. This bonding is performed, for example, by transferring an adhesive or using a thermosetting adhesive. After that, the substrate 32 is removed.

Next, a through hole for the ink supply path 51 is formed in the insulating material 36, the vibration plate 26, and the intermediate plate 40. The formation of the through holes is performed by, for example, excimer laser processing.

Next, as shown in FIG.
The partition plate 41 is joined to 28 and the insulating material 36. The thickness of the partition plate 41 is, for example, 23 μm. Thereafter, the driver IC 43 is bonded to the partition plate 41 so as to partition the common ink chamber 11 between the partition plate 41 and the partition plate 41.

As described above, according to the second embodiment, the common ink chamber 11 is divided by the driver IC 43, so that the members can be integrated and the cost can be reduced. Also, since the members can be integrated,
The head can be made smaller.

Since the ejection path from the pressure chamber 12 to the nozzle 14 is short, the flow resistance of the ink is reduced. In addition, the ink supply path 51 between the common ink chamber 11 and the pressure chamber 12 is short, and the flow resistance when supplying ink to the pressure chamber 12 is small. Therefore, ejection of ink droplets can be performed favorably.

<Third Embodiment> In an ink jet head 1 according to a third embodiment, a driver IC (substrate) 43 is joined to a main body plate 23, and a partition wall and a nozzle for partitioning the common ink chamber 11 into the driver IC 43 are provided. The function is also used.

As shown in FIGS. 8 and 9, a pressure chamber recess 21 is formed on the front surface of the main body plate 23, and the back side surface of the main body plate 23 is formed flush. In the third embodiment, the main body plate 23
However, the ink supply path 22 is not formed as in the first embodiment. As shown in FIG. 9, similarly to the first embodiment, the pressure chamber recess 21 has a substantially elliptical cross-sectional shape.

On the front side surface of the main body plate 23, an intermediate plate 40 is formed so as to cover a part of the concave portion 21 for the pressure chamber. Intermediate plate 40
Includes an ink discharge port 37 which forms a part of an ink discharge path 45 extending from the pressure chamber 12 to the nozzle 14, and an ink supply port 38 which forms a part of an ink supply path 51 which extends from the common ink chamber 11 to the pressure chamber 12. , And a central opening 39 slightly smaller than the pressure chamber 12
Are formed. The ink discharge port 37 and the ink supply port 38 are formed at both ends in the longitudinal direction of the pressure chamber 12, and the central opening 39 is located between the ink discharge port 37 and the ink supply port 38 so as to correspond to the center of the pressure chamber 12. Is formed.

On the front side of the intermediate plate 40, the diaphragm 26 is
The pressure chamber recess 21 is provided so as to cover the pressure chamber recess 23. The diaphragm 26 forms a part of a partition wall of the pressure chamber 12. Diaphragm
In the 26, openings having the same diameter are formed at positions corresponding to the ink supply ports 38 and the ink discharge ports 37, respectively.

A piezoelectric element 27 is formed on the front surface of the diaphragm 26. Individual electrodes 28 are formed on the front surface of the piezoelectric element 27. Pressure chamber in piezoelectric element 27 and individual electrode 28
The portion corresponding to 12 is a drive unit 35 that performs flexural deformation together with the diaphragm 26 to apply pressure to the ink in the pressure chamber 12. The piezoelectric element 27 and the individual electrodes 28 also have ink supply ports.
An opening corresponding to 38 is formed.

On the front side of the individual electrode 28, a partition plate 41 is provided. At a position corresponding to the central opening 39 in the partition plate 41, that is, a position corresponding to the drive unit 35, a concave displacement chamber concave portion 46 is formed on the back side. Note that the partition plate 41 also has openings corresponding to the ink supply ports 38 and the ink discharge ports 37, respectively.

A driver IC 43 having a drive circuit is joined to the front surface of the common ink chamber partition plate 41. On the back side of the driver IC 43, there is a recess for the common ink chamber.
44 are formed. In addition, at a position corresponding to the ink ejection port 37, an ink ejection path 45 extending from the back side to the front side is provided.
Are formed through. A tapered nozzle 14 is formed on the front side of the ink discharge path 45. That is, the driver IC 43 defines the common ink chamber 11 and includes the nozzles 14 for ejecting ink droplets.

The patterns of the piezoelectric elements 27 and the individual electrodes 28
This is the same as the first embodiment.

Next, a method for manufacturing the ink-jet head 1 will be described with reference to FIGS.

First, as shown in FIG. 10A, a substrate 32 for patterning is prepared. As the substrate 32, for example, a substrate having a thickness of 20 mm is used.

Next, as shown in FIG. 10B, a Pt film 33 for an individual electrode is formed on the surface of the substrate 32. The formation is performed by, for example, sputtering. The thickness of the Pt film 33 is, for example, 0.1 μm.

Next, as shown in FIG. 10C, a PZT film 34 for a piezoelectric element is formed on the surface of the Pt film 33. The formation is performed by, for example, sputtering. PZT
The thickness of the film 34 is, for example, 2 to 3 μm.

Next, as shown in FIG.
Divided patterning is performed on the t film 33 and the PZT film 34. This is a step of forming a pattern of the piezoelectric elements 27 and the individual electrodes 28. This patterning is performed by, for example, chemical etching or ion milling. After the etching, the surface is flattened.

Next, as shown in FIG. 10E, a plastic coating step is performed. This is a step of filling the portion removed by the patterning with an insulating material (plastic) 36 to insulate the individual electrodes. As this plastic, for example, polyimide is used.

Next, as shown in FIG. 10F, a vibration plate 26 is formed on the surface of the piezoelectric element 27 and the insulating material 36. This formation is performed by, for example, sputtering of Cr.
The thickness of the diaphragm 26 is, for example, 2 μm.

Next, as shown in FIG.
Patterning is performed by providing 40, and a through hole 52 for the ink discharge path 45 is formed. The thickness of the intermediate plate 40 is, for example, 25
μm. The formation of the through holes 52 is performed by, for example, excimer laser processing.

Next, as shown in FIG.
The main body plate 23 is bonded to 40, and the substrate 32 is removed. This bonding is performed using, for example, an adhesive transfer or a thermosetting adhesive.
Thereafter, the partition plate 41 is joined to the insulating material 36 and the individual electrodes 28,
The driver IC 43 is joined to the partition plate 41.

As described above, according to the third embodiment, the driver IC 43 controls the common ink chamber 11 and the ink ejection path.
Since 45 is formed, the members can be integrated, and the cost is reduced. In addition, the members can be integrated, and the size of the head can be further reduced.

[0100]

As described above, according to the present invention, the length of the pressure chamber in the longitudinal direction is made shorter than the length of the common ink chamber in the direction, so that the pressure chamber can be downsized. Thus, the responsiveness of the ink droplets in the pressure chamber can be improved. Therefore, the accuracy of recording such as printing is improved.

By positioning the actuator and the nozzle on the same surface side of the head main body, a large common ink chamber can be secured.

Further, the manufacturing cost can be reduced by forming the actuator on the nozzle plate.

By covering the actuator with a water-repellent coating material, the actuator can be protected and ink can be prevented from adhering to the actuator.

The driver IC is integrated with the head body,
By providing the function of the partition wall or nozzle of the common ink chamber, the members can be integrated and integrated, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of an ink jet printer.

FIG. 2 is a perspective view of a part of the inkjet head according to the first embodiment.

FIG. 3 is a front view of a part of the inkjet head according to the first embodiment.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIGS. 5A to 5H are manufacturing process diagrams of the inkjet head according to the first embodiment.

FIG. 6 is a diagram corresponding to FIG. 4 of an inkjet head according to a second embodiment.

FIGS. 7A to 7H are manufacturing process diagrams of an inkjet head according to a second embodiment.

FIG. 8 is a diagram corresponding to FIG. 4 of an inkjet head according to a third embodiment.

FIG. 9 is a diagram illustrating a front view shape of a pressure chamber and the like of an inkjet head according to a third embodiment.

FIGS. 10A to 10H are manufacturing process diagrams of an inkjet head according to a third embodiment.

FIG. 11 is a longitudinal sectional view of a part of a conventional inkjet head.

[Explanation of symbols]

 11 Common ink chamber 12 Pressure chamber 14 Nozzle 21 Recess for pressure chamber 22 Ink supply path 23 Main plate 24 Back plate 25 Nozzle plate 26 Vibration plate 27 Piezoelectric element 28 Individual electrode 29 Water-repellent coating material 30 Actuator 40 Intermediate plate 41 Partition plate

Claims (8)

[Claims] An actuator having a common ink chamber, a plurality of pressure chambers communicating with the common ink chamber, and a piezoelectric element, wherein the actuator is displaced by applying a voltage to the piezoelectric element, and the pressure is increased by applying a voltage to the piezoelectric element. In an ink jet head that applies pressure to ink in a chamber and ejects ink droplets from a nozzle by the pressure, the pressure chamber has a longitudinal length that is the same as the longitudinal direction of the pressure chamber in the common ink chamber. An ink jet head characterized in that it is formed shorter than the length. 2. The ink-jet head according to claim 1, wherein the back surface faces the back plate at a predetermined interval so as to define a common ink chamber between the back plate and the back plate. And a main body plate having a front surface on which a plurality of pressure chamber recesses are formed, and through which a plurality of ink supply paths connecting the common ink chamber and the pressure chamber recesses are formed; and And a nozzle plate provided on the front side of the main body plate so that a plurality of nozzles corresponding to the recesses are formed through the plurality of nozzles, and each nozzle covers a part of each of the recesses for the pressure chambers. A diaphragm provided on the front surface of the nozzle plate and covering each pressure chamber recess of the main body plate so as to define a pressure chamber together with the pressure chamber recess, wherein the piezoelectric element of the actuator is It is characterized by being provided on the front side of The ink-jet head to be. 3. The ink jet head according to claim 2, wherein the front surface of the actuator is covered with a water repellent coating material. 4. The ink-jet head according to claim 1, wherein a nozzle plate on which a nozzle is formed, a plurality of pressure chamber recesses are formed on a back surface of the nozzle plate, and the pressure is formed on a back surface of the nozzle plate. A main body plate having an ink discharge passage connecting the chamber concave portion and the nozzle formed therethrough; and the actuator has an ink supply port formed at a position corresponding to the pressure chamber concave portion so as to penetrate therethrough. A diaphragm provided on the back side of the main body plate so as to define each pressure chamber together with the recess; a piezoelectric element of the actuator is provided on a back side surface of the diaphragm; and a drive voltage is applied to the piezoelectric element. And a substrate provided on the back side of the actuator, the common ink chamber having a concave portion for partitioning the common ink chamber on the front surface. Ettoheddo. 5. The ink jet head according to claim 4, wherein a plurality of central openings provided between the main body plate and the vibration plate and corresponding to the center of each pressure chamber recess, and an ink supply port of the vibration plate. And an intermediate plate formed with a plurality of ink supply ports corresponding thereto, and provided between the actuator and the substrate so as to define a common ink chamber between the substrate and the substrate. An ink jet head, comprising: a recess formed at a position corresponding to each central opening; and a partition plate having openings formed through the openings corresponding to the ink supply ports of the vibration plate and the intermediate plate. 6. The ink-jet head according to claim 1, further comprising a main body plate having a front surface on which a plurality of pressure chamber recesses are formed, wherein the actuator supplies ink to a position corresponding to each of the pressure chamber recesses. A diaphragm is provided on the back side of the main body plate so that a mouth is formed therethrough so as to define each pressure chamber together with the concave portion for each pressure chamber, and the piezoelectric element of the actuator is provided on a front side surface of the vibration plate. A common ink that is provided on a front side of the actuator and includes a driving circuit that applies a driving voltage to the piezoelectric element, and a front surface on which a plurality of nozzles corresponding to each pressure chamber are formed, and a common ink chamber. An ink jet head comprising: a back side surface on which a chamber recess is formed; and a substrate through which an ink discharge path connected to each nozzle is formed. 7. The ink-jet head according to claim 6, wherein a plurality of central openings provided between the main body plate and the vibration plate and corresponding to the central portion of each pressure chamber recess, and the plurality of pressure chamber recesses are provided. An intermediate plate in which a plurality of ink supply ports and ink discharge ports corresponding to the end portions are formed through; and an intermediate plate provided between the actuator and the substrate so as to define a common ink chamber between the substrate and the substrate. A concave portion is formed at a position corresponding to the central opening on a surface facing the actuator, and a partition plate is formed through which the ink supply port and the ink discharge port corresponding to the ink supply port and the ink discharge port are formed. An ink jet head characterized by the following. 8. The ink jet head according to claim 1, wherein a plurality of pressure chamber rows in which pressure chambers are arranged in the sub-scanning direction are provided in the main scanning direction. The pressure chambers are arranged in a staggered manner at positions corresponding to adjacent pressure chambers in an adjacent pressure chamber row.