JP2000296617A - Ink jet recording head and ink jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording head and an ink jet recording apparatus capable of preventing the deformation and crack of a reservoir forming substrate. SOLUTION: In an ink jet recording head equipped with a nozzle forming member 16 having a plurality of nozzle orifices 15, a flow channel forming substrate 10 wherein pressure generating chambers 12 communicating with the nozzle orifices are demarcated and the piezoelectric element 300 provided to the surface opposite to the surface to which the nozzle forming member 16 is bonded of the flow channel forming substrate 10 to generate a pressure change in the pressure generating chambers 12, a reservoir forming substrate 20 having a reservoir part 21 constituting at least a part of a reservoir 100 communicating with the pressure generating chambers 12 to supply ink to the pressure generating chambers 12 is bonded to the surface on the side wherein the piezoelectric element 300 is formed of the flow channel forming substrate 10 and at least one beam-shaped reinforcing part 22 demarcating the reservoir part 21 is provided to the reservoir part 21 of the reservoir forming substrate 20 over the space between side walls opposed to each other to enhance the rigidity of the reservoir part 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a part of a pressure generating chamber which communicates with a nozzle opening for discharging ink droplets, which is constituted by a vibrating plate. The present invention relates to an ink jet recording head and an ink jet recording apparatus that eject ink droplets by displacement.

[0002]

2. Description of the Related Art A part of a pressure generating chamber communicating with a nozzle opening for discharging ink droplets is constituted by a vibrating plate, and the vibrating plate is deformed by a piezoelectric element to pressurize the ink in the pressure generating chamber to pass through the nozzle opening. Two types of ink jet recording heads that eject ink droplets have been commercialized, one using a longitudinal vibration mode piezoelectric actuator that expands and contracts in the axial direction of the piezoelectric element, and the other using a flexural vibration mode piezoelectric actuator. ing.

In the former method, the volume of the pressure generating chamber can be changed by bringing the end face of the piezoelectric element into contact with the diaphragm, so that a head suitable for high-density printing can be manufactured. There is a problem in that a difficult process of cutting into a comb shape in accordance with the arrangement pitch of the openings and an operation of positioning and fixing the cut piezoelectric element in the pressure generating chamber are required, and the manufacturing process is complicated.

On the other hand, in the latter, a piezoelectric element 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. In addition, there is a problem that a certain area is required due to the use of flexural vibration, and 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 by a film forming technique over the entire surface of the diaphragm as disclosed in Japanese Patent Application Laid-Open No. 5-286131. A proposal has been made in which the piezoelectric material layer is cut into a shape corresponding to the pressure generating chambers by a lithography method, and a piezoelectric element is formed so as to be independent for each pressure generating chamber.

According to this, the operation of attaching the piezoelectric element to the diaphragm becomes unnecessary, and not only can the piezoelectric element be manufactured by a precise and simple method such as lithography, but also the thickness of the piezoelectric actuator can be reduced. There is an advantage that it can be made thin and can be driven at high speed. In this case,
By providing at least only the upper electrode for each pressure generating chamber while keeping the piezoelectric material layer on the entire surface of the diaphragm, the piezoelectric actuator corresponding to each pressure generating chamber can be driven.

[0007] In such an ink jet recording head, ink is generally supplied to each pressure generating chamber from a reservoir serving as a common ink chamber for each pressure generating chamber. Further, the reservoir is provided with a compliance section for absorbing a pressure change at the time of driving the piezoelectric element in order to keep the internal pressure of the reservoir constant.

[0008]

However, in such an ink jet recording head, since the number of nozzles is increased, the size of the reservoir must be large enough to supply ink to each pressure generating chamber. Therefore, there is a problem that the strength of the reservoir forming substrate is necessarily reduced. Therefore, when heat is applied to the reservoir forming substrate in the mounting process, there is a problem that the substrate warps due to thermal expansion and cracks occur.

In view of such circumstances, it is an object of the present invention to provide an ink jet recording head and an ink jet recording apparatus which can prevent deformation and cracking of a reservoir forming substrate.

[0010]

According to a first aspect of the present invention, there is provided a nozzle forming member having a plurality of nozzle openings for discharging ink, the nozzle forming member being joined to the nozzle forming member and being provided with the nozzle opening. A flow channel forming substrate defining a pressure generating chamber communicating with the nozzle, and a pressure change chamber provided on a surface of the flow channel forming substrate opposite to a surface to which the nozzle forming member is joined, to change pressure in the pressure generating chamber. In the ink jet type recording head having a piezoelectric element to be generated, ink is supplied to each pressure generating chamber by communicating with the pressure generating chamber on a surface of the flow path forming substrate on which the piezoelectric element is formed. A reservoir forming substrate having a reservoir portion constituting at least a part of the reservoir is joined, and the reservoir portion of the reservoir forming substrate has an inner surface of a side wall defining the reservoir portion and facing each other. In an ink jet recording head, wherein a reinforcing portion of the at least one beam-like is provided over the.

In the first aspect, the rigidity of the reservoir portion is improved by the reinforcing portion, and cracking of the reservoir forming substrate due to thermal stress during mounting is prevented.

According to a second aspect of the present invention, in the first aspect, at least a part of the reinforcing portion is thinner than other portions of the reservoir forming substrate. It is in.

According to the second aspect, the rigidity of the reservoir is improved without deteriorating the function of the reservoir.

According to a third aspect of the present invention, in the second aspect, the reinforcing portion has a thickness smaller than that of the other portion by removing at least a part of the reinforcing member on the side of the flow path forming substrate. Ink-jet recording head.

According to the third aspect, the function of the reservoir can be reliably maintained, and the rigidity of the reservoir is improved.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the reinforcing portion is formed along a longitudinal direction of the piezoelectric element. It is in.

According to the fourth aspect, cracks due to thermal stress during mounting of the reservoir forming board are reliably prevented.

A fifth aspect of the present invention is the ink jet recording head according to any one of the first to fourth aspects, wherein the reservoir forming substrate is made of silicon.

In the fifth aspect, the reinforcing portion can be formed relatively easily by forming the reservoir forming substrate with a specific material.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the pressure generating chamber is formed on a silicon single crystal substrate by anisotropic etching, and each layer of the piezoelectric element is formed by a thin film and a lithography method. An ink jet recording head is characterized in that it is formed.

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

According to a seventh aspect of the present invention, there is provided an ink jet recording apparatus including the ink jet recording head according to any one of the first to sixth aspects.

According to the seventh aspect, it is possible to realize an ink jet recording apparatus with improved head reliability.

[0024]

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

(Embodiment 1) FIG. 1 is an exploded view showing an ink jet recording head according to Embodiment 1 of the present invention, and FIG. 2 is a plan view and a sectional view of FIG.

As shown in the figure, the flow path forming substrate 10 is 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 a 1-2 μm thick elastic film 50 of silicon dioxide formed by thermal oxidation in advance.

On the other hand, a silicon single crystal substrate is anisotropically etched on the opening surface of the flow path forming substrate
The pressure generating chambers 12 divided by the plurality of partition walls 11 are provided in parallel in the width direction, and on the outside in the longitudinal direction, a common ink chamber of each pressure generating chamber 12 communicates with a reservoir portion of a reservoir forming substrate described later. A communication portion 13 forming a part of the reservoir 100 is formed, and is communicated with one end of each pressure generating chamber 12 in the longitudinal direction via an ink supply path 14.

Here, in the anisotropic etching, when the 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. A second (1) which forms an angle of about 70 degrees with the (111) plane and forms an angle of about 35 degrees with the (110) plane.
11) plane, and the etching rate of the (111) plane is about 1/1 compared to the etching rate of the (110) plane.
This is performed using the property of being 80.
By such anisotropic etching, two first (11
Precision processing can be performed based on depth processing of a parallelogram formed by the 1) plane and two oblique second (111) planes, and the pressure generating chambers 12 can be arranged at high density. it can.

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. Each of the ink supply passages 14 communicating with one end of each of the pressure generating chambers 12 is formed shallower than the pressure generating chambers 12 and maintains a constant flow resistance of the ink flowing into the pressure generating chambers 12. That is, the ink supply path 14 is formed by partially etching (half-etching) the silicon single crystal substrate in the thickness direction. Note that the half etching is performed by adjusting the etching time.

On the opening side of the flow path forming substrate 10,
A nozzle forming member 16 provided with a nozzle opening 15 communicating with the pressure supply chamber 12 on the side opposite to the ink supply path 14 is fixed via an adhesive or a heat welding film. The thickness of the nozzle forming member 16 is, for example, 0.1 to 1
mm, the coefficient of linear expansion is 300 ° C. or less, for example, 2.5 to
It is made of 4.5 [× 10 ⁻⁶ / ° C.] glass ceramic or non-rusting steel. The nozzle forming member 16 entirely covers one surface of the flow path forming substrate 10 on one surface, and also serves as a reinforcing plate for protecting the silicon single crystal substrate from impact and external force. In addition, the nozzle forming member 16 is connected to the passage forming substrate 10.
May be formed of a material having substantially the same thermal expansion coefficient as that of the material. In this case, since the deformation of the flow path forming substrate 10 and the nozzle forming member 16 due to heat become substantially the same, the joining can be easily performed using a thermosetting adhesive or the like.

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 15 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 15 need to be formed with a groove width of several tens of μm with high accuracy.

On the other hand, on the elastic film 50 on the side opposite to the opening surface of the flow path forming substrate 10, for example, a thickness of about 0.2 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.
0. Here, the piezoelectric element 300 refers to a portion including the lower electrode film 60, the piezoelectric film 70, and the upper electrode film 80. Generally, one of the electrodes of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric film 70 are patterned for each pressure generating chamber 12. Here, a portion which is constituted by one of the patterned electrodes and the piezoelectric film 70 and in which a piezoelectric strain is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion 320. In the present embodiment, the lower electrode film 60 is used as a common electrode of the piezoelectric element 300 and the upper electrode film 80 is used as an individual electrode of the piezoelectric element 300. In any case, the piezoelectric active portion is formed for each pressure generating chamber. Also, here
The combination of the piezoelectric element 300 and the vibration plate whose displacement is generated by driving the piezoelectric element 300 is referred to as a piezoelectric actuator. In the example described above, the elastic film 50 and the lower electrode film 6
Although 0 functions as a diaphragm, the lower electrode film may also serve as an elastic film.

The piezoelectric element 300 of the flow path forming substrate 10
On the side, a reservoir forming substrate 20 having a reservoir portion 21 constituting at least a part of the reservoir 100 is joined. This reservoir portion 21 is basically formed in the width direction of the pressure generating chamber 12 so as to penetrate the reservoir forming substrate 20 in the thickness direction, and as described above, the communication portion of the flow path forming substrate 10. The reservoir 100 communicates with the pressure generating chamber 13 and serves as a common ink chamber for each of the pressure generating chambers 12.

At least one, for example, in the present embodiment, two beam-shaped reinforcing portions 22 are provided between the opposing side walls that define the reservoir portion 21.
In the present embodiment, the reinforcing portion 22 is formed on the surface of the reservoir portion 21 opposite to the joint surface with the flow path forming substrate 10 along the longitudinal direction of the piezoelectric element 300. Also,
In the present embodiment, the reinforcing portion 22 is formed of the reservoir forming substrate 20.
Is formed by half-etching from the side of the joint surface with the flow path forming substrate 10, and has a smaller thickness than other portions. Such a reinforcing portion 22 includes a flexible portion 2 described later.
It is preferable that the area be as large as possible within a range in which the area 3 can maintain the internal pressure of the reservoir 100 uniformly.

As described above, in the present embodiment, the reservoir 10
Since the beam-shaped reinforcing portions 22 are provided between the side walls defining 0, the rigidity of the reservoir portion 21 is improved, and deformation such as warpage of the reservoir forming substrate due to thermal stress during mounting can be prevented. In addition, it is possible to prevent the reservoir forming substrate from being cracked due to the deformation. Therefore, the durability and reliability of the head can be improved.

As the reservoir forming substrate 20, it is preferable to use a material having substantially the same coefficient of thermal expansion as that of the flow path forming substrate 10, such as glass or ceramic material. It was formed using a silicon single crystal substrate of the same material as that of No. 10. As a result, as in the case of the nozzle forming member 16 described above, even when both are bonded at a high temperature using a thermosetting adhesive, both can be securely bonded, and the manufacturing process is simplified. be able to.

Further, the sealing film 3 is provided on the surface of the reservoir forming substrate 20 opposite to the surface joined to the flow path forming substrate 10.
1 and a fixed board 32, a compliance board 30
Are joined. Here, the sealing film 31 is made of a material having low rigidity and flexibility (for example, a polyphenylene sulfide (PPS) film having a thickness of 6 μm), and one side of the reservoir 21 is sealed by the sealing film 31. Has been stopped. The fixing plate 32 is formed of a hard material such as a metal (for example, stainless steel (SUS) having a thickness of 30 μm). Since the region of the fixing plate 32 facing the reservoir 100 is an opening 33 completely removed in the thickness direction, one surface of the reservoir 100 is sealed only with the sealing film 31 having flexibility. The flexible portion 23 is deformable by a change in internal pressure, and the flexible portion 23 maintains the internal pressure of the reservoir 100 uniformly.

An ink inlet 25 for supplying ink to the reservoir 100 is formed on the compliance substrate 30 substantially outside the central portion in the longitudinal direction of the reservoir 100. Further, the reservoir forming substrate 20 is provided with an ink introduction path 26 that communicates the ink introduction port 25 with the side wall of the reservoir 100. In the present embodiment, the ink is supplied to the reservoir 100 by one ink inlet 25 and the ink inlet path 26. However, the present invention is not limited to this. For example, according to a desired ink supply amount, A plurality of ink introduction ports and ink introduction paths may be provided, or the opening area of the ink introduction ports may be increased to enlarge the ink flow path.

The ink jet type recording head of this embodiment takes in ink from the ink inlet 25 connected to external ink supply means (not shown),
After filling the inside with ink from 00 to the nozzle opening 15, each lower electrode film 60 corresponding to the pressure generating chamber 12 is made according to a recording signal from an external driving circuit (not shown).
A voltage is applied between the pressure generating chamber 12 and the upper electrode film 80 to deflect and deform the elastic film 50, the lower electrode film 60, and the piezoelectric film 70.
5 ejects ink droplets.

In this embodiment, the area of the reservoir forming substrate 20 facing the piezoelectric element 300 is
With enough space not to interfere with the movement of 00,
A piezoelectric element holding portion 24 capable of sealing the space is provided,
At least the piezoelectric active part 320 of the piezoelectric element 300 is sealed in the piezoelectric element holding part 24. In the present embodiment, the piezoelectric element holding section 24 is formed to have a size that covers the plurality of piezoelectric elements 300 arranged in parallel in the width direction.

As described above, the reservoir forming substrate 20 constitutes the reservoir 100 and also serves as a cap member for isolating the piezoelectric element 300 from the external environment, thereby preventing the piezoelectric element 300 from being broken by the external environment such as moisture. can do. In the present embodiment, the piezoelectric element holding section 24
Is merely sealed, but the inside of the piezoelectric element holding section 24 is kept at a low humidity by, for example, evacuating the space inside the piezoelectric element holding section 24 or setting it to a nitrogen or argon atmosphere. The piezoelectric element 300
Can be more reliably prevented.

In this embodiment, the piezoelectric film 70 and the upper electrode film 80 of the piezoelectric element 300 sealed by the piezoelectric element holding portion 24 are connected to the flow path from one end of the pressure generating chamber 12 in the longitudinal direction. An exposed portion 10 extending on the formation substrate 10 to the outside of the reservoir formation substrate 20 and exposing a surface of the flow path formation substrate 10 on the joining side with the reservoir formation substrate
a, an external wiring 4 such as a flexible cable
0 is connected.

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

For example, in the above embodiment, the reinforcing portion 22
Is provided on the surface of the reservoir forming substrate 20 opposite to the joining surface of the flow path forming substrate 10, but is not limited to this. For example, as shown in FIG.
May be provided on the joint surface side with the flow path forming substrate 10.

Further, for example, in the above-described embodiment, the entire reinforcing portion 22 is formed to be thinner than other portions.
For example, as shown in FIG. 4, for example, as shown in FIG. 4, the reinforcing portion 22 is formed to have basically the same thickness as the reservoir forming substrate 20, and a part of the joint surface side with the flow path forming substrate 10 is formed. May be a removal portion 22a from which a part in the thickness direction is removed. With such a structure, the strength of the reservoir forming substrate 20 can be further improved without lowering the function of the reservoir 100, and deformation due to heat during mounting can be reliably prevented.

In the above embodiment, two reinforcing portions 22 are provided. However, the present invention is not limited to this. For example, one reinforcing portion 22 or three or more reinforcing portions 22 may be provided. In any case, the shape of the reinforcing portion 22 is
What is necessary is just to be able to maintain the compliance of 3 so that the change in the internal pressure of the reservoir 100 can be absorbed.

In the embodiment described above, a thin-film type ink jet recording head manufactured by applying a film forming and lithography process is described as an example. However, the present invention is not limited to this. The present invention can also be applied to a thick film type ink jet recording head formed by a method such as sticking.

The ink jet recording head according to the above-described embodiment constitutes a part of a recording head unit having an ink flow path communicating with an ink cartridge or the like, and is mounted on an ink jet recording apparatus. FIG.
FIG. 2 is a schematic diagram illustrating an example of the ink jet recording apparatus.

As shown in FIG. 5, the recording head units 1A and 1B having the ink jet recording heads are provided with detachable cartridges 2A and 2B constituting ink supply means.
The carriage 3 on which B is mounted is provided movably in the axial direction on a carriage shaft 5 attached to the apparatus main body 4. The recording head units 1A and 1B are, for example,
Each of them ejects a black ink composition and a color ink composition.

The driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and a timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted moves along the carriage shaft 5. Moved. On the other hand, a platen 8 is provided on the apparatus main body 4 along the carriage shaft 5, and a recording sheet S, which is a recording medium such as paper fed by a paper feed roller (not shown), is wound around the platen 8. It is designed to be transported.

[0052]

As described above, according to the present invention, since the reinforcing portion for suppressing the deformation is provided in the reservoir portion of the reservoir forming substrate, the deformation due to heat at the time of mounting the flow path forming substrate is reduced. Can be suppressed. Therefore, it is possible to prevent cracks due to this deformation and to achieve an ink jet recording head with improved reliability.

[Brief description of the drawings]

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

FIG. 2 is a plan view and a cross-sectional view of the inkjet recording head according to the first embodiment of the present invention.

FIG. 3 is a partial perspective view of an ink jet recording head according to another embodiment of the present invention.

FIG. 4 is a partial perspective view of a reservoir forming substrate according to another embodiment of the present invention.

FIG. 5 is a schematic diagram of an ink jet recording apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 flow path forming substrate 12 pressure generating chamber 13 communication part 14 ink supply path 15 nozzle opening 16 nozzle forming member 20 reservoir forming substrate 21 reservoir part 22 reinforcing part 23 flexible part 24 piezoelectric element holding part 30 compliance substrate 31 sealing film 32 Fixing plate 60 Lower electrode film 70 Piezoelectric film 80 Upper electrode film 100 Reservoir 300 Piezoelectric element

Claims (7)

[Claims] A nozzle forming member having a plurality of nozzle openings for discharging ink; a flow passage forming substrate joined to the nozzle forming member and defining a pressure generating chamber communicating with the nozzle openings, respectively; A piezoelectric element provided on a surface of the flow path forming substrate opposite to a surface to which the nozzle forming member is joined and causing a pressure change in the pressure generating chamber; A reservoir forming substrate having a reservoir portion that forms at least a part of a reservoir that communicates with the pressure generation chambers and supplies ink to each pressure generation chamber is joined to a surface of the substrate on which the piezoelectric element is formed. Wherein the reservoir portion of the reservoir forming substrate is provided with at least one beam-shaped reinforcement portion between the side walls that define the reservoir portion and oppose each other. An ink jet recording head according to symptoms. 2. The ink jet recording head according to claim 1, wherein at least a part of the reinforcing portion is thinner than another portion of the reservoir forming substrate. 3. The ink jet recording head according to claim 2, wherein at least a part of the reinforcing portion on the side of the flow path forming substrate is removed and the thickness is smaller than other portions. 4. The ink jet recording head according to claim 1, wherein the reinforcing portion is formed along a longitudinal direction of the piezoelectric element. 5. The ink jet recording head according to claim 1, wherein the reservoir forming substrate is made of silicon. 6. 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 element is formed by a thin film and a lithography method. An ink jet recording head, characterized in that: 7. An ink jet recording apparatus comprising the ink jet recording head according to claim 1.