JP2003251805A - Inkjet recording head and inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording head which can hold ink discharge characteristics good at all times and can be made compact, and an inkjet recorder. <P>SOLUTION: The inkjet recorder has a channel forming substrate where pressure generation chambers 12 are formed to communicate with nozzle openings, and piezoelectric elements 300 comprising lower electrodes 60 set via a diaphragm to one face of the channel forming substrate, a piezoelectric layer 70 set on the lower electrodes 60 and upper electrodes 80 set on the piezoelectric layer 70. The lower electrodes 60 and the upper electrodes 80 are set independently of each other to regions corresponding to respective pressure generation chambers 12, and wiring electrodes 90 connected to respective upper electrodes 80 are set on the diaphragm at a region opposite to peripheral walls of one end side in a longitudinal direction of the pressure generation chambers 12, thereby making the upper electrodes 80 a common electrode for each of the piezoelectric elements 300. A resistance value of the common electrode is thus lowered. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric element, in which a part of a pressure generating chamber communicating with a nozzle opening for ejecting ink droplets is composed of a vibrating plate, and a piezoelectric element is formed on the surface of the vibrating plate. The present invention relates to an inkjet recording head and an inkjet recording device that eject ink droplets by displacement.

[0002]

2. Description of the Related Art A part of a pressure generating chamber that communicates with a nozzle opening for ejecting ink droplets is composed of a vibrating plate, and the vibrating plate is deformed by a piezoelectric element to pressurize ink in the pressure generating chamber to eject it from the nozzle opening. Two types of inkjet recording heads that eject ink droplets have been put into practical use: one that uses a longitudinal vibration mode piezoelectric actuator that expands and contracts in the axial direction of a piezoelectric element, and one that uses a flexural vibration mode piezoelectric actuator. ing.

The former allows the volume of the pressure generating chamber to be changed by bringing the end face of the piezoelectric element into contact with the vibrating plate, and a head suitable for high-density printing can be manufactured. There is a problem in that the manufacturing process is complicated because a difficult process of matching the array pitch of the openings and cutting into comb teeth or a work of positioning and fixing the cut piezoelectric element in the pressure generating chamber are required.

On the other hand, in the latter, the piezoelectric element can be formed on the vibration plate by a relatively simple process of sticking a green sheet of a piezoelectric material in conformity with the shape of the pressure generating chamber and firing it. 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 eliminate the disadvantage of the latter 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 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 lithographic method and a piezoelectric element is formed so as to be independent for each pressure generating chamber.

According to this, the work of attaching the piezoelectric element to the diaphragm becomes unnecessary, and not only the piezoelectric element can be densely formed by a precise and simple method such as a lithography method, but also the piezoelectric element. The advantage is that the thickness can be reduced and high speed driving is possible.

[0007]

However, in the ink jet recording head in which the piezoelectric elements are arranged in high density, when a large number of piezoelectric elements are simultaneously driven to eject a large number of ink droplets, a voltage drop occurs. As a result, the amount of displacement of the piezoelectric element becomes unstable and the ink ejection characteristics deteriorate.

Although such a problem can be solved by increasing the thickness of the common electrode and lowering the resistance value of the common electrode, the displacement of the vibrating plate due to the driving of the piezoelectric element is hindered and the ink droplets are prevented. There is a problem that the discharge amount of

This can also be solved by widening the area of the common electrode to lower the resistance value of the common electrode. However, in order to widen the area of the common electrode, it is necessary to widen the area of the head itself. There is a problem that it becomes large.

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 always maintain good ink ejection characteristics and can be downsized.

[0011]

According to a first aspect of the present invention for solving the above-mentioned problems, there is provided a flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening is formed, and one surface side of the flow path forming substrate. An ink jet recording head comprising: a lower electrode provided via a vibration plate, a piezoelectric layer provided on the lower electrode, and a piezoelectric element comprising an upper electrode provided on the piezoelectric layer. A region in which the lower electrode and the upper electrode are independently provided in regions corresponding to the respective pressure generating chambers, and the wiring electrodes connected to the respective upper electrodes face the peripheral wall on the one end side in the longitudinal direction of the pressure generating chambers. The inkjet recording head is characterized in that it is provided on the vibration plate and the upper electrode is a common electrode for each piezoelectric element.

In the first aspect, the resistance value of the common electrode of the piezoelectric element can be easily reduced without increasing the size of the head, and the voltage drop caused by simultaneously driving a large number of piezoelectric elements is prevented. To be done.

A second aspect of the present invention is characterized in that, in the first aspect, at least the vibrating plate in a region facing one longitudinal end of the pressure generating chamber is covered with the wiring electrode. It is in an inkjet recording head.

In the second aspect, it is possible to prevent the stress due to the driving of the piezoelectric element from being concentrated on the vibration plate in the region facing the longitudinal end of the pressure generating chamber.

According to a third aspect of the present invention, in the first or second aspect, at least the diaphragm in a region facing the other end portion in the longitudinal direction of the pressure generating chamber is made of the same conductive layer as the wiring electrode. The inkjet recording head is characterized by being covered with a protective layer.

In the third aspect, it is possible to prevent the stress due to the driving of the piezoelectric element from concentrating on the vibration plate in the region facing the longitudinal end of the pressure generating chamber.

According to a fourth aspect of the present invention, in the third aspect, the lower electrode is extended from the other end side in the longitudinal direction of the pressure generating chamber to a region facing the peripheral wall and the pressure generating chamber is formed. The inkjet recording head is characterized in that a lower electrode removing portion is formed by removing the lower electrode in a region facing the other end portion in the longitudinal direction, and the protective layer is formed in the lower electrode removing portion.

In the fourth aspect, it is possible to increase the rigidity of the vibrating plate in the region facing the longitudinal end of the pressure generating chamber without short-circuiting the lower electrode and the upper electrode.

A fifth aspect of the present invention is the ink jet method according to any one of the first to fourth aspects, characterized in that the wiring electrode is formed of a metal having a smaller specific resistance than the lower electrode. It is on the recording head.

In the fifth aspect, the resistance of the common electrode is surely reduced, and the occurrence of voltage drop is more reliably prevented.

A sixth aspect of the present invention is the ink jet recording head according to any one of the first to fifth aspects, wherein the thickness of the wiring electrode is 1 μm or more.

In the sixth aspect, the resistance of the common electrode is surely reduced, and the occurrence of voltage drop is more reliably prevented.

In a seventh aspect of the present invention, in any one of the first to sixth aspects, the pressure generating chamber is formed in a silicon single crystal substrate by anisotropic etching, and each layer of the piezoelectric element is formed and formed. The inkjet recording head is characterized by being formed by a lithography method.

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

An eighth aspect of the present invention is an ink jet recording apparatus including the ink jet recording head according to any one of the first to seventh aspects.

According to the eighth aspect, it is possible to realize an ink jet recording apparatus with stable ink ejection characteristics and improved reliability.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on embodiments.

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

As shown in the figure, the flow path forming substrate 10 is made of a silicon single crystal substrate having a plane orientation (110) in this embodiment, and its surface is made of silicon dioxide previously formed by thermal oxidation. An elastic film 50 and a protective film 51 having a thickness of 2 μm are formed.

The flow path forming substrate 10 is anisotropically etched through the opening 51a of the protective film 51 provided on one surface of the flow path forming substrate 10 to divide the pressure generating chamber 12 into a plurality of partition walls 11. Are arranged side by side in the width direction.
Further, on the outside in the longitudinal direction, a communication portion 13 that forms a reservoir 100 by communicating with a reservoir portion 31 of a reservoir forming substrate 30 described later is formed. The communicating portion 13 is communicated with one end portion of each pressure generating chamber 12 in the longitudinal direction via the ink supply passage 14.

Here, the anisotropic etching is performed by utilizing the difference in etching rate of the silicon single crystal substrate. For example, in this embodiment, the silicon single crystal substrate is set to K.
When it is dipped in an alkaline solution such as OH, it is gradually eroded and the first (111) plane perpendicular to the (110) plane and the first (111) plane
Forms an angle of about 70 degrees with the (111) plane of
A second (111) plane that makes an angle of about 35 degrees with the (0) plane appears, and the etching rate of the (111) plane is about 1/180 of the etching rate of the (110) plane. Is done using. By such anisotropic etching, it is possible to perform precision machining based on the depth machining of the parallelogram shape formed by the two first (111) planes and the two diagonal second (111) planes. The pressure generating chambers 12 can be arranged in 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 in the flow path forming substrate 1
It is formed by etching through almost 0 to reach the elastic film 50. Here, the elastic film 50 is
The amount of the alkaline solution that etches the silicon single crystal substrate is extremely small. Further, each ink supply passage 14 communicating with one end of each pressure generation chamber 12 is formed shallower than the pressure generation chamber 12, and keeps the flow resistance of the ink flowing into the pressure generation chamber 12 constant. That is, the ink supply path 14 is formed by etching the silicon single crystal substrate halfway in the thickness direction (half etching). The half etching is performed by adjusting the etching time.

The thickness of the flow path forming substrate 10 in which the pressure generating chambers 12 and the like are formed is preferably selected in accordance with the density at which the pressure generating chambers 12 are arranged. For example, 180 per inch (180dp
When arranging the pressure generating chambers 12 to about i), the thickness of the flow path forming substrate 10 is preferably about 180 to 280 μm, and more preferably about 220 μm. Further, when the pressure generating chambers 12 are arranged at a relatively high density of, for example, about 360 dpi, the thickness of the flow path forming substrate 10 is preferably 100 μm or less. This is because the array density can be increased while maintaining the rigidity of the partition walls 11 between the adjacent pressure generating chambers 12.

A nozzle plate 20 having a nozzle opening 21 communicating with each pressure generating chamber 12 on the side opposite to the ink supply passage 14 is provided on the opening side of the flow path forming substrate 10 with an adhesive or heat welding. It is fixed via a film or the like. The nozzle plate 20 has a thickness of, for example, 0.1 to 1
mm, a coefficient of linear expansion of 300 ° C. or less, for example, 2.5 to
It is made of glass ceramics of 4.5 [× 10 ⁻⁶ / ° C.] or rust-free steel. The nozzle plate 20 entirely covers one surface of the flow path forming substrate 10 with one surface, and also serves as a reinforcing plate that protects the silicon single crystal substrate from impact and external force. Further, the nozzle plate 20 is used as the flow path forming substrate 10.
It may be made of a material having substantially the same thermal expansion coefficient. In this case, since the flow path forming substrate 10 and the nozzle plate 20 have substantially the same deformation due to heat, they can be easily joined using a thermosetting adhesive or the like.

Here, the size of the pressure generating chamber 12 that applies the ink droplet ejection pressure to the ink and the size of the nozzle opening 21 that ejects 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 drops per inch, it is necessary to accurately form the nozzle openings 21 with a diameter of several tens of μm.

On the other hand, on the elastic film 50 on the side opposite to the opening surface of the flow path forming substrate 10, in this embodiment, it is made of zirconium oxide (ZrO ₂ ) and has a thickness of, for example, 1 to 2 μm.
The insulating layer 52 is provided, and the elastic film 50 and the insulating layer 52 serve as a diaphragm.

On the insulating layer 52, a lower electrode film 60 having a thickness of, for example, about 0.2 μm, a piezoelectric layer 70 having a thickness of, for example, about 1 μm, and a thickness of, for example, about 0 μm. .1 μm
The upper electrode film 80 and the upper electrode film 80 are laminated and formed in a process described later to form the piezoelectric element 300. Here, the piezoelectric element 300 includes a lower electrode film 60, a piezoelectric layer 70, and an upper electrode film 8.
Refers to the part containing 0. Generally, the piezoelectric element 300 is
One of the electrodes is used as a common electrode, and the other electrode and the piezoelectric layer 70 are patterned and formed for each pressure generating chamber 12. In the present embodiment, as described below, the lower electrode film 60, the piezoelectric Each of the body layer 70 and the upper electrode film 80 is formed by patterning for each pressure generating chamber 12.

That is, as shown in FIG. 3, in this embodiment, the lower electrode film 60 constituting the piezoelectric element 300 has a width slightly wider than the pressure generating chambers 12 in the region corresponding to each pressure generating chamber 12. It is patterned so as to be independent, and serves as an individual electrode of each piezoelectric element 300. Also,
The end portion of the lower electrode film 60 on the communicating portion 13 side of the pressure generating chamber 12 extends from the longitudinal end portion of the pressure generating chamber 12 to the peripheral wall, and although not shown, the piezoelectric element 3 is provided near the end portion.
00 is connected to a drive circuit or the like. In addition,
Lower electrode film 60 on the side opposite to the communicating portion 13 of the pressure generating chamber 12
Is located in the region facing the pressure generating chamber 12.

On the other hand, the upper electrode film 80 is patterned together with the piezoelectric layer 70 in the region facing each pressure generating chamber 12, and is connected to the wiring electrode 90 by the connection wiring drawn from each upper electrode film 80 so that each piezoelectric film is formed. It constitutes the common electrode of the element 300. That is, the wiring electrode 90 made of a conductive material is provided along the direction in which the pressure generating chambers 12 are arranged side by side on the insulating layer 52 in the region facing the peripheral wall on the communication portion 13 side of each pressure generating chamber 12. . Then, the wiring electrode 90 and each upper electrode film 80 are electrically connected by a connection wiring, in the present embodiment, a lead-out portion 91 pulled out from each wiring electrode 90, and the upper electrode film 80 is each piezoelectric element 300. It is a common electrode.

As the material of the wiring electrode 90, it is preferable to use a metal having a specific resistance smaller than that of the lower electrode film 60 such as gold (Au), copper (Cu), aluminum (Al). In this embodiment, gold (Au) /
A titanium (Ti) multilayer film is used. In addition, the wiring electrode 9
The thickness of 0 is not particularly limited, but is preferably 1 μm or more.

In the present embodiment, the upper electrode film 80 and the wiring electrode 90 are electrically connected by the lead-out portion 91 drawn out from the wiring electrode 90, but of course they are formed separately from the wiring electrode 90. You may make it electrically connect by the connection wiring.

In such a configuration, since the wiring electrode 90 constitutes a part of the common electrode of each piezoelectric element 300, the resistance value of the common electrode of the piezoelectric element 300 can be substantially reduced, and a large number of piezoelectric elements can be formed. Even if the elements are driven simultaneously, no voltage drop occurs. Therefore, it is possible to always eject ink droplets of a predetermined size, and it is possible to always maintain good print quality.

Further, since the wiring electrode 90 is formed of a metal having a relatively small specific resistance, the resistance value of the common electrode of the piezoelectric element 300 can be reduced in a relatively small area, so that the head can be miniaturized. Can be achieved.

The piezoelectric element 300 of the flow path forming substrate 10
On the side, a reservoir section 31 that constitutes at least a part of the reservoir 100 that serves as a common ink chamber for each pressure generating chamber 12 is provided.
The reservoir forming substrate 30 having the is bonded. In the present embodiment, the reservoir portion 31 is formed so as to penetrate the reservoir forming substrate 30 in the thickness direction and extend in the width direction of the pressure generation chamber 12, and is provided so as to penetrate the elastic film 50 and the insulating layer 52. The reservoir 100, which is connected to the communication portion 13 of the flow path forming substrate 10 via the through hole 53, serves as a common ink chamber for the pressure generating chambers 12.

As the reservoir forming substrate 30, it is preferable to use a material having substantially the same coefficient of thermal expansion as that of the flow passage forming substrate 10, such as glass or a ceramic material. It was formed using a silicon single crystal substrate of the same material.

In addition, the piezoelectric element 3 of the reservoir forming substrate 30
In a region facing 00, a piezoelectric element holding portion 32 that can seal the space is provided in a state where a space that does not hinder the movement of the piezoelectric element 300 is secured, and the piezoelectric element 300 includes the piezoelectric element holding portion 32. It is sealed inside.

The reservoir forming substrate 30 is located between the reservoir portion 31 and the piezoelectric element holding portion 32 of the reservoir forming substrate 30, that is, in the region corresponding to the ink supply passage 14.
Is provided with a through hole 33 penetrating in the thickness direction. One end of the lower electrode film 60 of each piezoelectric element 300 extends to the through hole 33 and is connected to an external wiring (not shown) by wire bonding or the like.

A compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded onto the reservoir forming substrate 30. Here, the sealing film 41
Is a material having low rigidity and flexibility (for example, a thickness of 6
and a reservoir portion 31 made of a sealing film 41.
One side is sealed. The fixing plate 42 is formed of a hard material such as metal (for example, stainless steel (SUS) having a thickness of 30 μm). Since the region of the fixing plate 42 facing the reservoir 100 is the opening 43 that is completely removed in the thickness direction, one surface of the reservoir 100 is sealed with only the flexible sealing film 41. Has been done.

Although not shown, the reservoir forming substrate 3
0 and the compliance substrate 40 include a reservoir 100.
An ink introducing port that communicates with the outside is formed, and ink is supplied from the ink introducing port into the reservoir 100.

In such an ink jet recording head of this embodiment, the ink is taken in from the external ink supply means (not shown) through the ink introduction port, and the interior from the reservoir 100 to the nozzle opening 21 is filled with the ink. After that, according to the recording signal from the drive circuit (not shown),
A voltage is applied between the lower electrode film 60 and the upper electrode film 80 corresponding to the pressure generating chamber 12 via external wiring, and the elastic film 50, the insulating layer 52, the lower electrode film 60, and the piezoelectric layer 70.
By flexurally deforming the ink, the pressure in each pressure generating chamber 12 increases, and an ink droplet is ejected from the nozzle opening 21.

An example of the method for manufacturing the ink jet recording head of this embodiment will be described below with reference to FIGS. 4 and 5. 4 and 5 are cross-sectional views of the pressure generating chamber 12 in the longitudinal direction.

First, as shown in FIG. 4A, about 110 wafers of a silicon single crystal substrate to be the flow path forming substrate 10 are prepared.
An elastic film 50 and a protective film 51 made of silicon dioxide are formed by thermal oxidation in a diffusion furnace at 0 ° C.

Next, as shown in FIG. 4B, the elastic film 5
An insulating layer 52 is formed on the surface of the insulating film 52. Specifically, the elastic film 50
After forming a zirconium layer on the surface of, for example, 500-1
The zirconium layer is thermally oxidized in a diffusion furnace at 200 ° C. to form the insulating layer 52 made of zirconium oxide.

Next, as shown in FIG. 4C, after forming the lower electrode film 60 on the entire surface of the insulating layer 52 by sputtering, the lower electrode film 60 is patterned to form an overall pattern. Platinum (Pt) or the like is suitable as a material for the lower electrode film 60. This is because the piezoelectric layer 70 described later, which is formed by the sputtering method or the sol-gel method, needs to be crystallized by baking at a temperature of about 600 to 1000 ° C. in the air atmosphere or the oxygen atmosphere after the film formation. Because. That is, the material of the lower electrode film 60 must be able to maintain the conductivity under such a high temperature and oxidizing atmosphere, and especially when lead zirconate titanate (PZT) is used as the piezoelectric layer 70. It is desirable that the change in conductivity due to the diffusion of lead oxide is small, and platinum is preferable for these reasons.

Next, as shown in FIG. 4D, the piezoelectric layer 70 is formed. The piezoelectric layer 70 preferably has crystals oriented. For example, in the present embodiment, a so-called sol-gel method is used in which a so-called sol in which a metal organic material is dissolved and dispersed in a catalyst is applied, dried, gelled, and fired at a high temperature to obtain a piezoelectric layer 70 made of a metal oxide. To form a piezoelectric layer 70 in which crystals are oriented. As a material for the piezoelectric layer 70, a lead zirconate titanate-based material is suitable for use in an inkjet recording head. The method for forming the piezoelectric layer 70 is not particularly limited, and may be formed by, for example, a sputtering method.

Further, after forming a precursor film of lead zirconate titanate by a sol-gel method or a sputtering method,
A method of growing crystals at a low temperature by a high-pressure treatment method in an alkaline aqueous solution may be used.

In any case, in the piezoelectric body layer 70 thus formed, crystals are preferentially oriented unlike the bulk piezoelectric body, and in the present embodiment, the piezoelectric body layer 70 has crystals. It has a columnar shape. Note that the preferential orientation means that the crystal orientation direction is not disordered, and a specific crystal plane is oriented in a substantially constant direction. Further, a thin film having a columnar crystal means a state in which crystals having a substantially columnar body are aggregated in a plane direction with the central axes substantially aligned with the thickness direction to form a thin film. Of course, it may be a thin film formed of preferentially oriented granular crystals. The thickness of the piezoelectric layer manufactured in the thin film process is generally 0.2 to 5 μm.

Next, as shown in FIG. 5A, the upper electrode film 80 is formed. The upper electrode film 80 may be made of a material having high conductivity, and many metals such as aluminum, gold, nickel and platinum, and a conductive oxide can be used. In this embodiment, platinum is deposited by sputtering.

Next, as shown in FIG. 5B, only the piezoelectric layer 70 and the upper electrode film 80 are patterned by etching to form the piezoelectric element 3 in the region facing each pressure generating chamber 12.
00 is formed.

Next, as shown in FIG. 5C, the wiring electrode 90 is formed. That is, after forming the wiring electrode 90 over the entire surface of the flow path forming substrate 10, the wiring electrode 90 is patterned by etching, and each upper electrode film 8 is formed by the extraction portion 91.
A wiring electrode 90 electrically connected to 0 is formed. The wiring electrode 90 is formed on the lower electrode film 60 as described above.
Since it is preferable to use a metal having a smaller specific resistance than that, a gold (Au) / titanium (Ti) multilayer film is formed by sputtering in this embodiment.

The above is the film forming process. After forming the film in this manner, anisotropic etching of the silicon single crystal substrate is performed with the above-described alkaline solution. That is, as shown in FIG. 5D, the protective film 51 is patterned to form the pressure generating chamber 12, the communicating portion 13, and the ink supply path 1.
The openings 51a having a predetermined shape are formed in a region facing 4 and the like, and the pressure generating chambers 12 and the like are formed by anisotropically etching the flow path forming substrate 10 through the openings 51a. After that, the through hole 53 is formed by penetrating the elastic film 50 and the insulating layer 52.

Actually, a large number of chips are simultaneously formed on one wafer by the above-described series of film formation and anisotropic etching, and after the process, one chip size as shown in FIG. The flow path forming substrate 10 is divided. Then, the reservoir forming substrate 30 and the compliance substrate 40 are sequentially adhered to and integrated with the divided flow path forming substrate 10 to form an ink jet recording head.

(Second Embodiment) FIG. 6 is a plan view showing a wiring pattern of an ink jet recording head according to a second embodiment.

The present embodiment is another example of the pattern shape of the wiring electrode 90, and as shown in FIG.
The first embodiment is the same as the first embodiment except that the vibrating plate in the region facing the vicinity of the end in the longitudinal direction and the wiring electrode 90 (lead-out portion 91) are formed so as to cover the end in the longitudinal direction of the piezoelectric element 300.

As described above, by covering the vibrating plate in the region opposed to the end portion in the longitudinal direction of the pressure generating chamber 12 with the wiring electrode 90, the rigidity of the vibrating plate is improved and the pressure is generated by the repeated deformation due to the driving of the piezoelectric element 300. It is possible to prevent stress from concentrating in the vicinity of the longitudinal end portion of the chamber 12. Therefore, due to repeated driving of the piezoelectric element 300, cracks or the like do not occur in the diaphragm, and durability and reliability can be improved.

Further, in the present embodiment, since the vicinity of the end portion of the piezoelectric element 300 is covered with the wiring electrode 90 (lead-out portion 91), the rigidity of the vicinity of the end portion in the longitudinal direction of the piezoelectric element 300 is enhanced, and the piezoelectric element 300. Piezoelectric element 3 when driving 300
The stress applied to the vicinity of the longitudinal end portion of 00 is suppressed. Therefore, when the piezoelectric element 300 is driven, the piezoelectric element 3
Since the amount of displacement at the end portion of 00 in the longitudinal direction is reduced, it is possible to prevent the piezoelectric layer 70 from being broken due to repeated displacement.

(Third Embodiment) FIG. 7 is a plan view showing a wiring pattern of an ink jet recording head according to a third embodiment.

In the second embodiment, the vibrating plate in the region facing the one end in the longitudinal direction of the pressure generating chamber 12 and the vicinity of the end in the longitudinal direction of the piezoelectric element 300 are covered with the wiring electrode 90.
In the present embodiment, as shown in FIG.
The vibrating plate in the vicinity of the other end in the longitudinal direction of 00 and in the region facing the other end in the longitudinal direction of the pressure generating chamber 12 is covered with the protective layer 110 made of the same conductive layer as the wiring electrode 90.

That is, in the present embodiment, the lower electrode film 60
In a region facing the vicinity of the other end portion in the longitudinal direction of the pressure generating chamber 12, a lower electrode film removing portion 61 from which the lower electrode film 60 is removed is formed to expose the insulating layer 52. The protective layer 110 is patterned in the lower electrode film removal portion 61 so as not to contact the lower electrode film 60.

With such a structure, as in the second embodiment, the rigidity of the vibrating plates at both longitudinal ends of the pressure generating chamber 12 and the vicinities of both ends of the piezoelectric element are increased, and the piezoelectric element 300 is repeatedly deformed by driving. Vibration plate and piezoelectric layer 70
Can be more reliably prevented from being destroyed.

(Other Embodiments) Although one embodiment of the present invention has been described above, the configuration of the present invention is not limited to the above.

For example, in the above-described embodiment, the thin film type ink jet recording head manufactured by applying the film formation and the lithographic process is taken as an example. However, the present invention is not limited to this, for example, a green sheet. The present invention can be applied to a thick film type ink jet recording head formed by a method such as sticking.

The present invention can also be applied to a long head by changing the thickness, width, etc. of the wiring electrode.

The ink jet recording head of each of these embodiments 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. Figure 8
It is a schematic diagram showing an example of the ink jet type recording device.

As shown in FIG. 8, in the recording head units 1A and 1B having an ink jet recording head, the cartridges 2A and 2B constituting the ink supply means are detachably provided, and the recording head units 1A and 1B are provided.
The carriage 3 on which B is mounted is provided on a carriage shaft 5 attached to the apparatus body 4 so as to be movable in the axial direction. The recording head units 1A and 1B are, for example,
The black ink composition and the color ink composition are respectively discharged.

Then, the driving force of the drive motor 6 is transmitted to the carriage 3 via a plurality of gears (not shown) and the timing belt 7, so that the carriage 3 having the recording head units 1A and 1B mounted thereon follows the carriage shaft 5. Be moved. On the other hand, a platen 8 is provided on the apparatus body 4 along the carriage shaft 5, and a recording sheet S, which is a recording medium such as paper fed by a feed roller (not shown), is conveyed onto the platen 8. It is like this.

[0077]

As described above, in the present invention, the lower electrode and the upper electrode are independently provided in the regions corresponding to the respective pressure generating chambers, and the wiring electrodes provided on the peripheral wall are connected to the respective upper electrodes. As a result, the upper electrode is used as the common electrode of each piezoelectric element, so that the resistance value of the common electrode can be lowered relatively easily without increasing the size of the head. Therefore, even if a large number of piezoelectric elements are driven at the same time, a voltage drop does not occur, and stable ink ejection characteristics can always be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing an inkjet recording head according to a first embodiment of the invention.

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

FIG. 3 is a plan view showing a wiring pattern of the ink jet recording head according to the first embodiment of the invention.

FIG. 4 is a cross-sectional view showing the manufacturing process of the inkjet recording head according to the first embodiment of the invention.

FIG. 5 is a cross-sectional view showing the manufacturing process of the ink jet recording head according to the first embodiment of the invention.

FIG. 6 is a plan view showing a wiring pattern of an ink jet recording head according to a second embodiment of the invention.

FIG. 7 is a plan view showing a wiring pattern of an ink jet recording head according to a third embodiment of the invention.

FIG. 8 is a schematic diagram of an inkjet recording apparatus according to an embodiment of the present invention.

[Explanation of symbols]

10 Flow path forming substrate 12 Pressure generation chamber 20 nozzle plate 21 nozzle opening 30 Reservoir forming substrate 40 compliance board 50 elastic membrane 52 insulating layer 60 Lower electrode film 61 Lower electrode film removal section 70 Piezoelectric layer 80 Upper electrode film 90 wiring electrodes 91 Drawer 110 protective layer 300 Piezoelectric element

Claims (8)

[Claims] 1. A flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening is formed, a lower electrode provided on one surface side of the flow path forming substrate via a vibrating plate, and provided on the lower electrode. An ink jet recording head comprising a piezoelectric layer composed of a piezoelectric layer and an upper electrode provided on the piezoelectric layer, wherein the lower electrode and the upper electrode are independently provided in regions corresponding to the respective pressure generating chambers. And a wiring electrode connected to each upper electrode is provided on the diaphragm in a region facing the circumferential wall on the one end side in the longitudinal direction of the pressure generating chamber,
An ink jet recording head, wherein the upper electrode is a common electrode for each piezoelectric element. 2. The ink jet recording head according to claim 1, wherein at least the vibration plate in a region facing one longitudinal end of the pressure generating chamber is covered with the wiring electrode. 3. The pressure generating chamber according to claim 1, wherein at least the vibration plate in a region facing the other end in the longitudinal direction of the pressure generating chamber is covered with a protective layer made of the same conductive layer as the wiring electrode. An inkjet recording head characterized by: 4. The lower electrode according to claim 3, wherein the lower electrode extends from the other end in the longitudinal direction of the pressure generating chamber to a region facing the peripheral wall and faces the other end in the longitudinal direction of the pressure generating chamber. An ink jet recording head, characterized in that a lower electrode removal portion is formed by removing the lower electrode in a region, and the protective layer is formed in the lower electrode removal portion. 5. The ink jet recording head according to claim 1, wherein the wiring electrode is formed of a metal having a specific resistance smaller than that of the lower electrode. 6. The ink jet recording head according to claim 1, wherein the wiring electrode has a thickness of 1 μm or more. 7. The pressure generating chamber according to claim 1, wherein the pressure generating chamber is formed in a silicon single crystal substrate by anisotropic etching, and each layer of the piezoelectric element is formed by film formation and a lithography method. An ink jet recording head characterized by being present. 8. An ink jet recording apparatus comprising the ink jet recording head according to claim 1.