JPH1178009A - Ink-jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent cross talk and poor ink droplet discharge in a state recording density is improved. SOLUTION: The recording head comprises a channel forming substrate 100 having at least two rows 13 of a pressure generating room 12 sectioned by a plurality of partition walls and communicating with a nozzle opening on one side, a vibrating plate comprising a part of the pressure generating room 12 on the other side, and a piezoelectric oscillator comprising a piezoelectric active part formed in a region facing with the pressure generating room 12. A reinforcing member 20, which is a member different from the channel forming substrate 10, is adhered onto the one side of the channel forming substrate 10, at least at the position corresponding with the part between the row 13 and the row 13 of the pressure generating room 12 so that the reinforcing member 20 can receive the displacement generated by the drive of the piezoelectric oscillator for restraining the distortion of the channel forming substrate 10 and preventing the cross talk.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure generating chamber communicating with a nozzle opening for discharging ink droplets, wherein the pressure generating chamber is partially constituted by a vibrating plate, and a piezoelectric layer on the surface of the vibrating plate is formed. The present invention relates to an ink jet recording head that ejects ink droplets by displacement of a layer.

[0002]

2. Description of the Related Art A part of a pressure generating chamber which communicates with a nozzle opening for discharging ink droplets is constituted by a vibrating plate. There are two types of ink-jet recording heads that eject ink droplets from a piezoelectric vibrator, which uses a longitudinal vibration mode piezoelectric vibrator, in which a piezoelectric vibrator expands and contracts in the axial direction, and a flexural vibration mode piezoelectric vibrator. Has been put to practical use.

In the former method, the volume of the pressure generating chamber can be changed by bringing the end face of the piezoelectric vibrator into contact with the vibrating plate, so that a head suitable for high-density printing can be manufactured. A complicated process of cutting the piezoelectric vibrators into a comb-tooth shape in accordance with the arrangement pitch of the nozzle openings, and a work of positioning and fixing the separated piezoelectric vibrators in the pressure generating chambers, which complicates the manufacturing process. There is.

On the other hand, in the latter, a piezoelectric vibrator can be formed on a diaphragm by a relatively simple process of sticking a green sheet of a piezoelectric material according to the shape of a pressure generating chamber and firing the green sheet. However, due to the use of flexural vibration, a certain area is required, and there is a problem that high-density arrangement is difficult.

On the other hand, in order to solve the latter disadvantage of the recording head, a uniform piezoelectric material layer is formed over the entire surface of the diaphragm by a film forming technique as disclosed in Japanese Patent Application Laid-Open No. 5-286131. It has been proposed that the piezoelectric material layer is cut into a shape corresponding to the pressure generating chamber by a lithography method, and a piezoelectric vibrator is formed so as to be independent for each pressure generating chamber.

[0006] According to this, the work of attaching the piezoelectric vibrator to the diaphragm is not required, and the precision of the lithography method is used.
In addition to the fact that the piezoelectric vibrator can be manufactured by a simple and simple method, there is an advantage that the thickness of the piezoelectric vibrator can be reduced and high-speed driving is possible.

Further, in this case, for example, a silicon single crystal substrate is used as a substrate, and flow paths such as a pressure generation chamber and a reservoir are formed by anisotropic etching to reduce the opening area of the pressure generation chamber as much as possible. Thus, the recording density can be improved.

[0008]

However, in order to increase the recording density, it is necessary to reduce the wall thickness of the partition which divides the pressure generating chamber, thereby decreasing the rigidity of the partition which divides the pressure generating chamber. However, there are problems such as crosstalk and defective ejection of ink droplets.

In view of such circumstances, an object of the present invention is to provide an ink jet recording head capable of preventing crosstalk and defective ink droplet ejection in a state where recording density is improved.

[0010]

According to a first aspect of the present invention, there is provided at least two rows of pressure generating chambers which communicate with a nozzle opening on one surface and are partitioned by a plurality of partition walls. Ink jet recording comprising a flow path forming substrate provided on the other surface with a vibrating plate constituting a part of the pressure generating chamber and a piezoelectric vibrator formed of a piezoelectric active portion formed in a region facing the pressure generating chamber. In the head, on the other surface of the flow path forming substrate, a reinforcing member that is a member separate from the flow path forming substrate is fixed at a position corresponding to at least a row between the rows of the pressure generating chambers. The ink jet recording head is characterized in that:

In the first aspect, since the reinforcing member receives the displacement caused by the driving of the piezoelectric vibrator, the deflection of the flow path forming substrate is suppressed, and the crosstalk is prevented.

According to a second aspect of the present invention, in the first aspect, the reinforcing member is a rod-shaped member extending along the direction in which the pressure generating chambers are arranged. It is in.

In the second aspect, the bending of the flow path forming substrate is suppressed by the rod-shaped member.

According to a third aspect of the present invention, in the first or second aspect, the nozzle openings are arranged in two rows at positions corresponding to respective inner ends of the at least two rows of pressure generating chambers, The reinforcing member is provided between the two nozzle rows, in the ink jet recording head.

In the third aspect, since the reinforcing member is provided at a position corresponding to the vicinity of the nozzle opening, crosstalk is prevented.

According to a fourth aspect of the present invention, in the third aspect, the at least two rows of the pressure generating chambers of the flow path forming substrate have an outer end opposite to a position corresponding to the nozzle opening. An ink jet printer, wherein an adjacent position is provided with a reservoir for receiving ink supply from the outside, and the reservoir and each of the outer ends of the pressure generating chamber are communicated with each other via an ink supply port. In the recording head.

In the fourth aspect, since the reservoir is formed together with the pressure generating chamber in the flow path forming substrate, the strength of the flow path forming substrate is reduced. However, the bending is suppressed by the reinforcing member, and the crosstalk is reduced. Is prevented.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the pressure generating chamber is formed by anisotropic etching on a silicon single crystal substrate, and each layer of the piezoelectric vibrator is formed by film formation. And an ink jet recording head formed by a lithography method.

According to the fifth aspect, an ink jet recording head having high-density nozzle openings can be manufactured in a large amount and relatively easily.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on one embodiment.

(Embodiment 1) FIG. 1 is an assembly perspective view showing an ink jet recording head according to an embodiment of the present invention, and FIG. 2 shows a cross-sectional structure of one of the pressure generating chambers in the longitudinal direction. FIG.

As shown in the figure, the flow path forming substrate 10 is formed of a silicon single crystal substrate having a plane orientation (110) in this embodiment. As the flow path forming substrate 10, usually 150 to 3
A thickness of about 00 μm is used.
Those having a thickness of about 0 to 280 μm, more preferably about 220 μm are suitable. This is because the arrangement density can be increased while maintaining the rigidity of the partition wall between the adjacent pressure generating chambers.

One surface of the flow path forming substrate 10 is an opening surface, and the other surface is formed with an elastic film 50 having a thickness of 1 to 2 μm and made of silicon dioxide previously formed by thermal oxidation.

On the other hand, a silicon single crystal substrate is anisotropically etched on the opening surface of the flow path forming substrate
Row 1 of pressure generating chambers 12 partitioned by a plurality of partition walls 11
3 are arranged in a substantially U-shape so as to surround three rows of the two rows of pressure generating chambers 12, and each of the pressure generating chambers 1.
An ink supply port 15 for communicating the reservoir 2 with the reservoir 14 at a constant fluid resistance is formed. In addition, an ink introduction hole 16 for supplying ink to the reservoir 14 from outside is formed at a substantially central portion of the reservoir 14.

Here, in the anisotropic etching, when a silicon single crystal substrate is immersed in an alkaline solution such as KOH, the substrate is gradually eroded and the first (111) plane perpendicular to the (110) plane is formed. The second (11) which forms an angle of about 70 degrees with the (111) plane and forms an angle of about 35 degrees with the above (110).
1) plane appears, and the etching rate of the (111) plane is about 1/18 as compared with the etching rate of the (110) plane.
This is performed using the property of being 0. By such anisotropic etching, two first (111)
Precision processing can be performed based on the depth processing of a parallelogram formed by two surfaces and two oblique second (111) surfaces, and the pressure generating chambers 12 can be arranged at high density.

In this embodiment, the long side of each pressure generating chamber 12 is formed by the first (111) plane, and the short side is formed by the second (111) plane. The pressure generating chamber 12 is provided on the flow path forming substrate 1.
It is formed by etching until it reaches the elastic film 50 almost through 0. Here, the elastic film 50 is
The amount attacked by the alkaline solution for etching the silicon single crystal substrate is extremely small. Further, each ink supply port 15 communicating with one end of each pressure generating chamber 12 is connected to one of the pressure generating chambers 12.
It is formed shallower. That is, the ink supply port 15
Is formed by etching (half-etching) the silicon single crystal substrate halfway in the thickness direction. Note that the half etching is performed by adjusting the etching time.

Further, on the opening side of the flow path forming substrate 10,
A nozzle plate 18 in which a nozzle opening 17 communicating with the ink supply port 15 of each pressure generating chamber 12 on the opposite side is formed is fixed via an adhesive or a heat welding film. The thickness of the nozzle plate 18 is, for example, 0.1 to 1
mm, the coefficient of linear expansion is 300 ° C. or less, for example, 2.5
It is made of glass ceramics having a density of up to 4.5 [× 10 ⁻⁶ / ° C.] or non-rusting steel. The nozzle plate 18
One surface completely covers one surface of the flow path forming substrate 10 and also serves as a reinforcing plate for protecting the silicon single crystal substrate from impact and external force.

Here, the size of the pressure generating chamber 12 for applying the ink droplet ejection pressure to the ink and the size of the nozzle opening 17 for ejecting the ink droplet depend on the amount of the ejected ink droplet, the ejection speed, and the ejection frequency. Optimized. For example,
When recording 360 ink droplets per inch, the nozzle openings 17 need to be formed with a groove width of several tens of μm with high accuracy.

On the other hand, the thickness of the elastic film 50 on the opposite side of the opening surface of the flow path forming substrate 10 is, for example, about 0.5 μm.
A lower electrode film 60, a piezoelectric film 70 having a thickness of, for example, about 1 μm, and an upper electrode film 80 having a thickness of, for example, about 0.1 μm are formed by lamination in a process to be described later. (Piezoelectric element). Thus, the elastic film 50
In the area facing each pressure generating chamber 12, a piezoelectric vibrator is provided independently for each pressure generating chamber 12, but in the present embodiment, the lower electrode film 60 is a common electrode of the piezoelectric vibrator. Although the upper electrode film 80 is used as an individual electrode of the piezoelectric vibrator, there is no problem even if the upper electrode film 80 is reversed for convenience of a drive circuit and wiring. In any case, a piezoelectric active portion is formed for each pressure generating chamber 12. In the present embodiment, as described in detail below, the piezoelectric film 70 and the upper electrode film 80 are formed for each pressure generating chamber 12.

In this embodiment, on the surface opposite to the opening surface of the flow path forming substrate 10, a reinforcing member extending along the direction in which the rows 13 are arranged is provided at a position facing between the rows 13 of the pressure generating chambers 12. The member 20 is fixed. Here, the reinforcing member 20 is
This is for reinforcing the strength of the flow path forming substrate 10 along the direction in which the rows 13 of the pressure generating chambers 12 are arranged, and may be fixed via an adhesive or a heat welding film. Also, the reinforcing member 2
The material of 0 is not particularly limited, and may be a material having high rigidity such as a metal, and a material having a linear expansion coefficient similar to that of the flow path forming substrate 10 may be used to prevent generation of stress due to a temperature change. .

Here, a process for forming the piezoelectric film 70 and the like on the flow path forming substrate 10 made of a silicon single crystal substrate will be described with reference to FIGS.

As shown in FIG. 3A, first, a wafer of a silicon single crystal substrate serving as the flow path forming substrate 10 is
Thermal oxidation is performed in a diffusion furnace at 0 ° C. to form an elastic film 50 made of silicon dioxide.

Next, as shown in FIG. 3B, a lower electrode film 60 is formed by sputtering. Pt or the like is preferable as the material of the lower electrode film 60. This is because a piezoelectric film 70 to be described later, which is formed by sputtering or a sol-gel method, has a thickness of 600 to 100 in an air atmosphere or an oxygen atmosphere after the film formation.
This is because it is necessary to perform crystallization by firing at a temperature of about 0 ° C. That is, the material of the lower electrode film 70 must be able to maintain conductivity at such a high temperature and in an oxidizing atmosphere. In particular, when PZT is used as the piezoelectric film 70, the conductivity due to the diffusion of PbO It is desirable that there is little change in sex, and Pt is preferred for these reasons.

Next, as shown in FIG. 3C, a piezoelectric film 70 is formed. The piezoelectric film 70 can be formed by sputtering, but in this embodiment, a so-called sol in which a metal organic substance is dissolved and dispersed in a solvent is applied, dried and gelled, and further baked at a high temperature. A so-called sol-gel method for obtaining a piezoelectric film 70 made of an oxide is used. As a material for the piezoelectric film 70, a lead zirconate titanate (PZT) -based material is suitable when used in an ink jet recording head.

Next, as shown in FIG. 3D, an upper electrode film 80 is formed. The upper electrode film 80 only needs to be a material having high conductivity, and many metals such as Al, Au, Ni, and Pt, and a conductive oxide can be used. In the present embodiment, P
t is formed by sputtering.

Next, as shown in FIG. 3E, the upper electrode film 80 and the piezoelectric film 70 are patterned so that a piezoelectric vibrator is provided for each pressure generating chamber 12. FIG. 3E shows a case where the piezoelectric film 70 is patterned with the same pattern as the upper electrode film 80. However, as described above, the piezoelectric film 70 does not necessarily need to be patterned. This is because, when a voltage is applied using the pattern of the upper electrode film 80 as an individual electrode, an electric field is applied only between each upper electrode film 80 and the lower electrode film 60 which is a common electrode. This has no effect. However, in this case, it is necessary to apply a large voltage to obtain the same excluded volume. Therefore, it is preferable to pattern the piezoelectric film 70 as well. Thereafter, the lower electrode film 60 is patterned to remove unnecessary portions.

Here, the patterning is performed by forming a resist pattern and then performing etching or the like.

The resist pattern is formed, for example, by applying a negative resist by spin coating or the like and performing exposure, development, and baking using a mask having a predetermined shape. Of course, a positive resist may be used instead of the negative resist.

The etching is performed using a dry etching apparatus, for example, an ion milling apparatus until the silicon dioxide film is exposed. After the etching, the resist pattern is removed using an ashing device or the like.

As the dry etching method, a reactive etching method or the like may be used in addition to the ion milling method. It is also possible to use wet etching instead of dry etching, but the patterning accuracy is somewhat inferior to the dry etching method, and the upper electrode film 8
Since the material of 0 is also limited, it is preferable to use dry etching.

Next, as shown in FIG. 4A, an insulator layer 90 is formed so as to cover the periphery of the upper electrode film 80 and the side surfaces of the piezoelectric film 70. Suitable materials for the insulator layer 90 are as described above, but in the present embodiment, a negative photosensitive polyimide is used.

Next, as shown in FIG. 4B, a window 90a is formed in a portion facing each communication portion 14 by patterning the insulator layer 90. The window 90 a is for connecting a conductor pattern 100 described later and the upper electrode film 80.

Next, for example, a conductor such as Cr-Au is formed on the entire surface and then patterned to form a conductor pattern 100.

The above is the film forming process. After forming the film in this manner, as shown in FIG. 4C, the silicon single crystal substrate is subjected to anisotropic etching with the above-described alkali solution to form the pressure generating chamber 12 and the like. In addition,
The series of film formation and anisotropic etching described above
A large number of chips are simultaneously formed on one wafer, and after completion of the process, the wafer is divided into flow path forming substrates 10 having one chip size as shown in FIG. Further, the divided flow path forming substrate 10 is sequentially bonded and integrated with the nozzle plate 18 and the reinforcing member 20 to form an ink jet recording head.

The ink jet head thus configured takes in ink from an ink inlet 16 connected to an external ink supply means (not shown), fills the inside from the reservoir 14 to the nozzle opening 17 with ink, and then supplies the external ink (not shown). Pressure is generated by applying a voltage between the lower electrode film 60 and the upper electrode film 80 via the conductive pattern 100 in accordance with a recording signal from the drive circuit to cause the elastic film 50 and the piezoelectric film 60 to bend and deform. The pressure in the chamber 12 increases, and ink droplets are ejected from the nozzle openings 17.

At this time, in this embodiment, the reinforcing member 20
A diaphragm made of an elastic film 50 and a lower electrode film 60;
The deflection of the piezoelectric film 70 is received, the deflection of the flow path forming substrate 10 is suppressed, and crosstalk is prevented.

The reinforcing member 20 may be provided not only between the rows 13 of the pressure generating chambers 20 but also outside the row 13.

(Embodiment 2) FIG. 5 is an assembly perspective view of an ink jet recording head according to Embodiment 2.

This embodiment is the same as the above-described embodiment in that the reinforcing members 20 are fixed between the rows 13, but in this embodiment, a plurality of flow members to which the reinforcing members 20 are fixed are fixed. The path forming substrate 10 is fixed to a fixing member 25. The fixing member 25 has a concave portion 25a into which the flow path forming substrate 10 is fitted. The illustrated fixing member 25 is a fixing member 25 having a shape capable of fitting the three flow path forming substrates 10.

(Other Embodiments) One embodiment of the present invention has been described above, but the basic configuration of the ink jet recording head is not limited to the above.

In the above-described embodiment, the reservoir 14 is formed together with the pressure generating chamber 12 in the flow path forming substrate 10, but a member forming the common ink chamber may be provided so as to overlap the flow path forming substrate. .

FIG. 6 is an exploded perspective view of the embodiment configured as described above. In this embodiment, the sealing plate 110, the common ink chamber forming plate 120, the thin plate 130, and the ink chamber side plate 140 are sandwiched between the nozzle substrate 18A having the nozzle openings 17A formed therein and the flow path forming substrate 10A. , The pressure generating chamber 12A and the nozzle opening 17A so as to penetrate them.
And a nozzle communication port 31 that communicates with. That is, the common ink chamber 32 is defined by the sealing plate 110, the common ink chamber forming plate 120, and the thin plate 130, and each pressure generating chamber 12A and the common ink chamber 32 are formed in the sealing plate 110. The ink is communicated via the ink communication hole 33. The sealing plate 110 is also provided with an ink introduction hole 34 for introducing ink from outside into the supply ink chamber 32. A penetrating portion 35 is formed in the ink chamber side plate 140 located between the thin plate 130 and the nozzle substrate 18A at a position facing each of the supply ink chambers 32, and a nozzle opening generated when ink droplets are ejected. The thin wall 130 is allowed to absorb the pressure directed to the opposite side to 11A, so that the other pressure generating chambers 12A can use the common ink chamber 32 to generate unnecessary positive or negative pressure. Pressure can be prevented from being applied. Note that the thin plate 130 and the ink chamber side plate 140 may be formed integrally.

In this embodiment as well, the reinforcing member 20 is provided at a position opposite to the opening 13 of the flow path forming substrate 10A and between the rows 13 of the pressure generating chambers 12A.
Is fixed, crosstalk can be prevented.

In each of the embodiments described above, a thin-film type ink jet recording head which can be manufactured by applying a film forming and lithography process is described as an example.
Of course, the present invention is not limited to this. For example, a piezoelectric film is formed by laminating substrates to form a pressure generating chamber, or a piezoelectric film is formed by attaching a green sheet or by screen printing, or a piezoelectric film formed by crystal growth. The present invention can be applied to ink jet recording heads having various structures, such as those that form a recording medium.

Further, in each of the above-described embodiments, the connection portion between the upper electrode film and the lead electrode may be provided at any place, and may be at any end or the center of the pressure generating chamber. .

Further, the example in which the insulator layer is provided between the piezoelectric vibrator and the lead electrode has been described. However, the present invention is not limited to this. The conductive film may be thermally welded, and the anisotropic conductive film may be connected to the lead electrode, or may be connected using various bonding techniques such as wire bonding.

As described above, the present invention can be applied to ink-jet recording heads having various structures, as long as the gist of the present invention is not contradicted.

[0058]

As described above, in the present invention,
By fixing the reinforcing member at a position facing between the rows of the pressure generating chambers on the side opposite to the pressure generating chamber forming surface of the flow path forming substrate, the deflection of the flow path forming substrate is suppressed, and the crosstalk is suppressed. The effect that it can prevent is produced.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an ink jet recording head according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the ink jet recording head according to the first embodiment of the present invention.

FIG. 3 is a view showing a thin film manufacturing process according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a thin film manufacturing process according to the first embodiment of the present invention.

FIG. 5 is an assembled perspective view of an ink jet recording head according to Embodiment 2 of the present invention.

FIG. 6 is an exploded perspective view of an ink jet recording head according to another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 flow path forming substrate 12 pressure generating chamber 14 reservoir 15 ink supply port 16 ink introduction port 17 nozzle opening 18 nozzle plate 50 elastic film 60 lower electrode film 70 piezoelectric film 80 upper electrode film 90 insulator layer 90a contact hole 100 conductor pattern

Claims (5)

[Claims] 1. A vibrating plate having at least two rows of pressure generating chambers which are communicated with a nozzle opening on one surface and are divided by a plurality of partitions, and a diaphragm which constitutes a part of the pressure generating chambers on the other surface. In an ink jet recording head including a flow path forming substrate provided with a piezoelectric vibrator formed of a piezoelectric active portion formed in a region opposed to the generation chamber, at least on the other surface of the flow path forming substrate, An ink jet recording head, wherein a reinforcing member, which is a separate member from the flow path forming substrate, is fixed at a position corresponding to between the rows of the pressure generating chambers. 2. The ink jet recording head according to claim 1, wherein the reinforcing member is a rod-shaped member extending along the direction in which the pressure generating chambers are arranged. 3. The at least two rows of pressure generating chambers according to claim 1, wherein the nozzle openings are arranged in two rows at positions corresponding to respective inner ends of the at least two rows of pressure generating chambers. An ink jet recording head provided between nozzle rows. 4. The external device according to claim 3, wherein a position adjacent to an outer end of the at least two rows of pressure generating chambers of the flow path forming substrate opposite to a position corresponding to the nozzle opening is externally provided. An ink-jet recording head, wherein a reservoir for receiving the ink supply is provided, and the reservoir and each of the outer ends of the pressure generating chamber are communicated via an ink supply port. 5. The pressure generating chamber according to claim 1, wherein the pressure generating chamber is formed on a silicon single crystal substrate by anisotropic etching, and each layer of the piezoelectric vibrator is formed by film formation and lithography. An ink jet recording head, characterized in that: