JP2001270125A - Ink-jet recording head and ink-jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink-jet recording head and an ink-jet recording device capable of preventing breakage of a channel forming substrate. SOLUTION: In an ink-jet recording head comprising a channel forming substrate 10 with a pressure generating chamber 12 communicating with a nozzle opening partitioned by a plurality of partition walls 11, and a piezoelectric element 300 disposed one on side surface side of the channel forming substrate 10 via a vibration plate, comprising a lower electrode 60, a piezoelectric layer 70 and an upper electrode 80, a driving circuit 110 for driving the piezoelectric element 300 is provided on the piezoelectric element 300 side of the channel forming substrate 10 as well as the piezoelectric element 300 and the driving circuit 110 are connected via a driving wiring 120 made of a bonding wire, with the connection part 90a of the piezoelectric element 300 and the driving wiring 120 disposed in a region facing the partition walls 11 for preventing breakage of the channel forming substrate 10 at the time of connecting the driving wiring 120.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric element formed in a part of a pressure generating chamber communicating with a nozzle opening for discharging an ink drop via a vibration plate, and the ink drop is discharged by displacement of the piezoelectric element. The present invention relates to an ink jet recording head and an ink jet recording apparatus.

[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 the nozzle opening. Two types of ink jet recording heads that eject ink droplets have been put into practical use, one using a longitudinal vibration mode piezoelectric actuator in which a piezoelectric element expands and contracts in the axial direction, 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.

This eliminates the need for attaching the piezoelectric element to the vibration plate, which not only allows the piezoelectric element to be manufactured by a precise and simple method such as lithography, but also reduces the thickness of the piezoelectric element. There is an advantage that it can be made thin and can be driven at high speed.

In any case, such an ink jet recording head requires a driving circuit such as a semiconductor integrated circuit (IC) for driving the piezoelectric element, and this driving circuit is located near the ink jet recording head. It is installed. By connecting the electrode wiring extending from the piezoelectric element on the flow path forming substrate to an external wiring such as a bonding wire extending from the driving circuit, the piezoelectric element and the driving circuit are electrically connected. Connected.

[0008]

However, in such a configuration, an ink flow path formed in the flow path forming substrate exists below the connection between the electrode wiring and the external wiring. Therefore, there is a problem that the flow path forming substrate is broken by adding the bonding wire when bonding.

In view of such circumstances, an object of the present invention is to provide an ink jet type recording head and an ink jet type recording apparatus which prevent the flow path forming substrate from being destroyed.

[0010]

According to a first aspect of the present invention, there is provided a flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening is defined by a plurality of partition walls. In an ink jet recording head comprising a lower electrode provided on one surface side of the substrate via a vibration plate, a piezoelectric element composed of a piezoelectric layer and an upper electrode, the piezoelectric element side of the flow path forming substrate has A drive circuit for driving the piezoelectric element is provided, and the piezoelectric element and the drive circuit are connected via a drive wire made of a bonding wire, and a connecting portion between the piezoelectric element and the drive wire faces the partition. The ink jet recording head is provided in a region where the ink jet recording head is operated.

In the first aspect, since the ink flow path does not exist below the connection portion, when the drive wiring composed of the bonding wire is connected, the load causes the flow path forming substrate to crack or the like. Can be prevented.

According to a second aspect of the present invention, in the first aspect, a lead electrode extends from an upper electrode of the piezoelectric element to a region facing the partition wall, and the vicinity of the leading end of the lead electrode is the connecting portion. An ink jet recording head is characterized in that:

In the second aspect, by extending the lead electrode, a connection portion can be easily formed in a region facing the partition.

According to a third aspect of the present invention, in the first or second aspect, the connection portion is provided outside a longitudinal end of the pressure generating chamber. In the head.

In the third aspect, by disposing the connecting portion outside the longitudinal end of the pressure generating chamber, the connecting portion is easily exposed, and the connection of the drive wiring is facilitated.

According to a fourth aspect of the present invention, in any one of the first to third aspects, further comprising a bonding substrate bonded to the piezoelectric element side of the flow path forming substrate, wherein the drive circuit is provided with the bonding member. An ink jet recording head is provided above.

According to the fourth aspect, the drive circuit can be easily arranged on the piezoelectric element side of the flow path forming substrate.

According to a fifth aspect of the present invention, in the fourth aspect, the bonding substrate can seal the space in a region facing the piezoelectric element in such a manner that a space is secured so as not to hinder its movement. An ink jet type recording head having a piezoelectric element holding portion.

In the fifth aspect, destruction of the piezoelectric element due to the external environment is prevented.

A sixth aspect of the present invention is the ink jet recording head according to the fourth or fifth aspect, wherein the drive circuit is formed directly on the joining member.

In the sixth aspect, the drive circuit can be formed relatively easily.

According to a seventh aspect of the present invention, there is provided an ink jet recording head according to the sixth aspect, wherein the driving circuit is a semiconductor integrated circuit.

In the seventh aspect, the drive circuit can be formed relatively easily.

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

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

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

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

[0028]

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 made 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 a 1-2 μm thick elastic film 50 made of silicon dioxide previously formed by thermal oxidation.

On the other hand, the opening surface of the flow path forming substrate 10 is anisotropically etched on a silicon single crystal 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. The ink supply path 14 is also partitioned by the partition 11 like the pressure generating chamber 12.

Here, in the anisotropic etching, when a silicon single crystal substrate is immersed in an alkaline solution such as KOH, it is gradually eroded, and the first (111) plane perpendicular to the (110) plane and the first (111) plane 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.

A nozzle plate 20 having a nozzle opening 21 communicating with the pressure supply chamber 12 on the opposite side of the ink supply path 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, 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 plate 20 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. Further, the nozzle plate 20 is connected to the flow path 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 plate 20 due to heat become substantially the same, it is possible to easily join them 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 21 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 21 need to be formed with a diameter 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 layer 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 laminated and formed by a process described later, and the piezoelectric element 30 is formed.
0. Here, the piezoelectric element 300 refers to a portion including the lower electrode film 60, the piezoelectric layer 70, and the upper electrode film 80. In general, one of the electrodes of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric layer 70 are patterned for each of the pressure generating chambers 12. Here, a portion which is constituted by one of the patterned electrodes and the piezoelectric layer 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. However, there is no problem even if the upper electrode film 80 is reversed for convenience of a drive circuit and wiring. 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 diaphragm whose displacement is generated by driving the piezoelectric element 300 is referred to as a piezoelectric actuator.

The piezoelectric element 300 of the flow path forming substrate 10
On the side, a reservoir forming substrate 30 having a reservoir part 31 constituting at least a part of the reservoir 100 is joined. In this embodiment, the reservoir portion 31 penetrates the reservoir forming substrate 30 in the thickness direction, and
Are formed over the width direction. Then, as described above, the reservoir 100 which is communicated with the communication portion 13 of the flow path forming substrate 10 through the through hole 51 formed in the elastic film 50 and serves as a common ink chamber of each pressure generating chamber 12 is configured. I have.

As the reservoir forming substrate 30, for example, it is preferable to use a material having substantially the same thermal expansion coefficient as that of the flow path forming substrate 10, such as glass or a ceramic material. It was formed using a silicon single crystal substrate of the same material. As a result, as in the case of the nozzle plate 20 described above, both can be securely bonded to each other even at a high temperature using a thermosetting adhesive. Therefore, the manufacturing process can be simplified.

Further, the reservoir forming substrate 30 includes:
The compliance substrate 40 including the sealing film 41 and the fixing plate 42 is joined. Here, the sealing film 41 is made of a material having low rigidity and flexibility (for example, a polyphenylene sulfide (PPS) film having a thickness of 6 μm), and the sealing film 41 seals one surface of the reservoir 31. Has been stopped. The fixing plate 42 is made of a hard material such as metal (for example, stainless steel (SU) having a thickness of 30 μm.
S) etc.). The reservoir 10 of the fixing plate 42
Since the region opposing to 0 is the opening 43 completely removed in the thickness direction, one surface of the reservoir 100 is sealed only with the sealing film 41 having flexibility, and the internal pressure changes. Thus, the flexible portion 32 is deformable.

An ink inlet 35 for supplying ink to the reservoir 100 is formed on the compliance substrate 40 substantially outside the central portion in the longitudinal direction of the reservoir 100. Further, the reservoir forming substrate 30 is provided with an ink introduction path 36 that communicates the ink introduction port 35 with the side wall of the reservoir 100. In the present embodiment, the ink is supplied to the reservoir 100 by one ink introduction port 35 and the ink introduction path 36. 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 reservoir forming substrate 30 also serves as a sealing plate that blocks the piezoelectric element 300 from the external environment. In a region facing the piezoelectric element 300, a space that does not hinder the movement of the piezoelectric element 300 is provided. A piezoelectric element holding portion 33 capable of sealing the space in a secured state is provided. Then, at least the piezoelectric active part 320 of the piezoelectric element 300
Are sealed in the piezoelectric element holding portion 33.

On such a reservoir forming substrate 30,
A driving circuit 110 for driving the piezoelectric element 300 is mounted, and is electrically connected to the piezoelectric element 300 via a driving wire 120 made of a bonding wire. In addition,
The drive circuit 110 may be a circuit board or a semiconductor integrated circuit (IC) including the drive circuit.

Here, the piezoelectric element 300 and the driving circuit 110
Will be described in detail.

As shown in FIG. 2A, the piezoelectric element 300
From the vicinity of one end of the upper electrode film 80 in the longitudinal direction.
A lead electrode 90 extends in a region opposed to the peripheral wall of the partition wall 2, and a distal end thereof has a partition wall 11 for partitioning the pressure generating chamber 12 and the like.
Above, for example, in the present embodiment, it is located on the partition 11 in a region corresponding to the ink supply path 14.

In the reservoir forming substrate 30, a through groove 37 penetrating in the thickness direction is provided in a region facing the tip of the lead electrode 90 over the rows of the pressure generating chambers 12. The wiring 120 has one end connected to the drive circuit 110 and the other end connected to the tip of the lead electrode 90 via the through groove 37. That is, the connecting portion 90 a between the lead electrode 90 extended from the piezoelectric element 300 and the drive wiring 120 is provided in a region facing the partition 11.

As described above, by providing the connection portion 90a between the lead electrode 90 extended from the piezoelectric element 300 and the drive wiring 120 in the area facing the partition 11, the drive electrode 120 made of a bonding wire is provided on the lead electrode 90. This can prevent the flow path forming substrate 10 from being broken due to a load applied when connecting them, thereby improving the yield and realizing a head with improved reliability.

In this embodiment, the connecting portion 90a is
The connection portion 90a can be easily exposed by the through groove 37 because the connection portion 90a is provided on the partition 11 in a region corresponding to the ink supply path 14, that is, outside the longitudinal end of the pressure generating chamber 12. The drive wiring 120 can be connected relatively easily.

The ink jet recording head of this embodiment takes in ink from an ink inlet 35 connected to an external ink supply means (not shown), and fills the inside from the reservoir 100 to the nozzle opening 21 with ink. After that, a voltage is applied between the lower electrode film 60 and the upper electrode film 80 corresponding to the pressure generating chamber 12 in accordance with a recording signal from an external drive circuit (not shown), and the elastic film 5
0, the lower electrode film 60 and the piezoelectric layer 70 are flexibly deformed, whereby the pressure in each pressure generating chamber 12 is increased, and ink droplets are ejected from the nozzle openings 21.

In this embodiment, the connecting portion 90 a between the lead electrode 90 extended from the piezoelectric element 300 and the drive wiring 120 is connected to the partition 11 in the region corresponding to the ink supply path 14.
Although it was provided above, it may of course be on the partition 11 in a region corresponding to the pressure generating chamber 12.

In the present embodiment, the lead electrode 90 extends from the longitudinal end of the piezoelectric element 300 to a region facing the partition 11, but the arrangement of the lead electrode is not particularly limited. For example, as shown in FIG. 3, the piezoelectric element 300 may extend from a substantially central portion in the width direction end surface to a region facing the partition 11. In this case, it is necessary to remove the lower electrode film 60 in a region where the lead electrode 90 extends.

In any case, by providing the connecting portion 90a between the piezoelectric element 300 and the drive wiring 120 on the partition wall 11, that is, in a region other than the portion opposed to the ink flow path, the flow path is formed as described above. Destruction of the substrate 10 can be prevented.

(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-described embodiment, the reservoir forming substrate 30 is joined to the flow path forming substrate 10, and the driving circuit 110 is provided on the reservoir forming substrate 30.
However, the present invention is not limited to this.
Any structure may be used as long as the drive circuit 110 is provided on the side.

In the above embodiment, a thin-film type ink jet recording head manufactured by applying a film forming and lithography process has been 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.

Further, the ink jet recording head of each of the 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. FIG.
FIG. 2 is a schematic diagram illustrating an example of the ink jet recording apparatus.

As shown in FIG. 4, 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.

[0059]

As described above, according to the present invention, the piezoelectric element and the driving circuit are connected by the driving wiring composed of the bonding wire, and the connection between the driving wiring and the piezoelectric element is provided on the partition wall. . Accordingly, when the drive wiring is connected to the piezoelectric element, it is possible to prevent the flow path forming substrate from cracking or the like due to the load, and it is possible to manufacture a head with improved yield and improved reliability.

[0060]

[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 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 main part plan view showing another example of the ink jet recording head according to the first embodiment of the present invention.

FIG. 4 is a schematic perspective view showing an ink jet recording apparatus according to one embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 flow path forming substrate 11 partition 12 pressure generating chamber 20 nozzle plate 30 reservoir forming substrate 40 compliance substrate 50 elastic film 60 lower electrode film 70 piezoelectric layer 80 upper electrode film 90 lead electrode 110 drive circuit 120 drive wiring 300 piezoelectric element

Claims (9)

[Claims] 1. A flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening is defined by a plurality of partition walls, a lower electrode provided on one surface side of the flow path forming substrate via a diaphragm, and a piezoelectric element. In an ink jet recording head including a piezoelectric element including a body layer and an upper electrode, a drive circuit for driving the piezoelectric element is provided on the piezoelectric element side of the flow path forming substrate, and the piezoelectric element and An ink jet recording head, wherein a drive circuit is connected via a drive wire made of a bonding wire, and a connection portion between the piezoelectric element and the drive wire is provided in a region facing the partition. 2. The device according to claim 1, wherein a lead electrode extends from an upper electrode of the piezoelectric element to a region facing the partition, and a portion near a tip end of the lead electrode serves as the connection portion. Inkjet recording head. 3. The ink jet recording head according to claim 1, wherein the connecting portion is provided outside a longitudinal end of the pressure generating chamber. 4. The method according to claim 1, further comprising a bonding substrate bonded to the piezoelectric element side of the flow path forming substrate, wherein the drive circuit is provided on the bonding member. Characteristic inkjet recording head. 5. The method according to claim 4, wherein the bonding substrate has a piezoelectric element holding portion capable of sealing a space in a region facing the piezoelectric element in a state in which a space that does not hinder the movement is secured. Characteristic inkjet recording head. 6. The ink jet recording head according to claim 4, wherein the drive circuit is formed directly on the joining member. 7. An ink jet recording head according to claim 6, wherein said drive circuit is a semiconductor integrated circuit. 8. 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: 9. An ink jet recording apparatus comprising the ink jet recording head according to claim 1.