JP2000334968A - Manufacture of ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture suitably to form in a large size or a multi-nozzle capable of preventing a warp, a crack or the like when a piezoelectric element is baked by connecting a green sheet containing a piezoelectric material as a main component on a main flat surface of a ceramic board after finally baking. SOLUTION: A green sheet 60 in which a green sheet containing a lead zirconate-titanate as a main component and an inner electrode layer are alternately laminated is manufactured. Two green sheets 60 are positioned at predetermined positions of a main flat surface 61a of a ceramic board 61 after finally baking as a head board and adhered. Then, the board 61 and the sheets 60 are baked in a integral state to obtain a piezoelectric element 63. Thereafter, the element 63 is slit to form a slit groove 64 arriving at the board 61 and divided into a plurality of the piezoelectric elements 12. Thus, the sheet 60 is connected and integrally baked with the board 61 to supplement an insufficiency in a mechanical strength of the element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an ink jet head, and more particularly to a method of manufacturing an ink jet head having a piezoelectric element bonded to a head substrate.

[0002]

2. Description of the Related Art As an ink jet head for an ink jet recording apparatus (including an image forming apparatus) used in a printer, a facsimile, a copying machine, etc., for example, as described in Japanese Patent Application Laid-Open No. 8-108540, An actuator unit in which a stacked piezoelectric element is joined to a liquid chamber unit that ejects ink droplets by displacement of the piezoelectric element is known.

As a method of manufacturing such an ink jet head, for example, the above-mentioned publication and Japanese Patent Application Laid-Open No. 9-156114
There are those described in Japanese Patent Application Laid-open No. This method will be described with reference to FIG. 6 and FIG.
As shown in FIG. 3, the baked piezoelectric elements 100, 100 are positioned at predetermined positions on the main plane 101a of the head substrate 101, and two piezoelectric elements are placed on the main plane 101a of the head substrate 101, as shown in FIG. The piezoelectric elements 100 are bonded to each other, slit processing is performed until reaching the head substrate 101 as shown in FIG. 3C, and the piezoelectric elements 100 are divided into a plurality of piezoelectric elements 102 by slit grooves 104. As shown, a frame 1 as a component is placed on a head substrate 101.
05 are joined.

[0004] Then, in order to make the heights of the bonded piezoelectric element 102 and the component 105 equal, as shown in FIG.
The upper surface 105a of the piezoelectric element 102 and the upper surface 105a of the component 105 are adjusted to have a plane accuracy of 0. As shown in FIG. 005 or less.

In order to increase the printing speed of the inkjet recording apparatus, it is necessary to increase the driving frequency of the head or to increase the number of nozzles of the head. Of these, increasing the driving frequency of the head requires a change in the basic configuration of the head, and therefore increasing the number of nozzles is easier to increase the printing speed.

However, in the above-described inkjet head, the piezoelectric element has a long and thin plate shape. In order to increase the number of nozzles, it is necessary to further lengthen the piezoelectric element. However, when the piezoelectric element, which is usually formed of ceramics, is elongated in such a manner, the mechanical strength is extremely reduced, which causes a problem in mass productivity. Further, when the piezoelectric element is fired, warpage or the like occurs, and the yield of the piezoelectric element itself is reduced.

Therefore, as described in, for example, JP-A-7-23708 and JP-A-10-100403, prior to firing the piezoelectric element, the piezoelectric element is bonded to a diaphragm as a head component and then integrally fired. Has been proposed.

[0008]

However, in an ink jet head using a piezoelectric element, the vibrating plate is an important component for determining the ink droplet ejection characteristics. As described above, when the piezoelectric element and the vibrating plate are integrally fired, In addition, the material of the diaphragm is limited, and the degree of freedom in design is reduced. Also,
Although this method utilizes the d31 displacement of the piezoelectric element, it is preferable to use the d33 displacement of the piezoelectric element from the viewpoint of increasing the speed and the density of the head.

The present invention has been made in view of the above points, and has as its object to provide a method of manufacturing an ink jet head suitable for increasing the number of nozzles.

[0010]

In order to solve the above-mentioned problems, a method of manufacturing an ink jet head according to the present invention comprises:
A green sheet containing a piezoelectric material as a main component is joined to the main surface of the ceramic substrate after the final firing to integrally fire. In this case, after the layer material of the same material as the ceramic substrate is joined to the green sheet, it can be integrally fired. Further, an adhesive layer may be formed between the ceramic substrate and / or a layer member made of the same material as the ceramic substrate and the green sheet, and the adhesive layer is made of a paste-like material mainly composed of the same material as the piezoelectric element. It is preferable to use

Further, after integrally firing the ceramic substrate and the green sheet, an electrode layer can be formed on a surface of the exposed surface of the piezoelectric element that is perpendicular to the main plane of the ceramic substrate. Furthermore, after forming the electrode layer, the surface of the exposed surface of the piezoelectric element parallel to the main plane of the ceramic substrate may be ground to remove the electrode layer on the parallel surface.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an exploded perspective view of an ink jet head to which the present invention is applied, FIG. 2 is an enlarged cross-sectional view of a main part in a direction orthogonal to a channel direction (nozzle arrangement direction) of the head, and FIG. It is an expanded sectional view.

The ink jet head includes a drive unit 1 as an actuator unit, a liquid chamber unit 2
And a head cover 3. Drive unit 1
Is a ceramic substrate, for example, an insulating head substrate 11 made of barium titanate, alumina, forsterite or the like.
A plurality of laminated piezoelectric elements 12 as energy generating elements are arranged in two rows and joined together, and a frame is a component made of resin, ceramic, or the like surrounding the periphery of each of the two rows of piezoelectric elements 12. The members 13 are joined by an adhesive 14.

The plurality of piezoelectric elements 12 are provided between piezoelectric elements 17 (to be referred to as “driving sections”) to which driving pulses for causing ink to be formed into droplets and to fly are formed. A piezoelectric element (hereinafter, referred to as a “non-driving unit”) serving as a liquid chamber support member that is located and receives a driving pulse and simply fixes the liquid chamber unit 2 to the substrate 11.
... are alternately configured.

Here, as the piezoelectric element 12, a laminated piezoelectric element having ten or more layers is used. This laminated piezoelectric element has a thickness of 10 to 50 μm / 1, for example, as shown in FIG.
Layer of lead zirconate titanate (PZT) 20 and a thickness of several μ
An internal electrode 21 made of silver / paradium (AgPd) of m / 1 layer is alternately laminated, but the material used for the piezoelectric element is not limited to the above, and other electromechanical conversion elements may be used. Can also.

The internal electrodes 21 of each piezoelectric element 12 are left and right end face electrodes 22 and 23 made of AgPd every other layer (the opposing face sides of the two piezoelectric element rows are end face electrodes 22, and the non-opposing face sides are end face electrodes). 23). On the other hand, as shown in FIG.
Each pattern of the common electrode 24 and the individual electrode 25 is provided by Au plating, AgPt paste printing, AgPd paste printing, or the like.

The opposite end electrodes 22 of the piezoelectric elements 12 in each row are connected to the common electrode 24 via a conductive adhesive 26.
On the other hand, the non-opposing end surface electrodes 23 of the piezoelectric elements 12 in each row are connected to the individual electrodes 25 via the conductive adhesive 26 in the same manner. Thereby, the driving unit 17
When a drive voltage is applied to the drive unit 17, an electric field is generated in the stacking direction, and the driving unit 17 is displaced in the stacking direction (d 33).
Direction displacement) occurs. As shown in FIG. 2, the common electrode 24 has a hole 13a formed in the frame member 13.
By filling the inside with the conductive adhesive 26, the pattern connected to each piezoelectric element is conducted.

On the other hand, the liquid chamber unit 2 comprises a diaphragm 31 having a multilayer structure composed of a laminate of metal thin films and a liquid chamber partition member having a two-layer structure composed of a photosensitive resin layer composed of dry film resist (DFR). 32 and a nozzle plate 33 made of metal, resin, or the like, are sequentially laminated, and are formed by heat fusion. By each of these members, one piezoelectric element 12
(Driving unit 17), a diaphragm 34 corresponding to the one piezoelectric element 12, a pressurized liquid chamber 35 pressurized via each diaphragm 34, and both sides of the pressurized liquid chamber 35. Common liquid chambers 36, 36 for introducing ink to be supplied to the pressurized liquid chamber 35, and a pressurized liquid chamber 35 and common liquid chambers 36, 36.
Ink supply paths 37, 37 communicating with the pressure liquid chamber 35.
One channel is formed by the nozzle 38 communicating with the nozzle, and a plurality of channels are provided in two rows.

The diaphragm 31 is made of a nickel plating film having a two-layer structure, and is formed integrally with the diaphragm portion 34 corresponding to the driving portion 17 and at the center of the diaphragm portion 34 for joining with the driving portion 17. Corresponding to the island-shaped convex portion 40, the partition wall portion 41 which becomes a beam to be joined to the non-driving portion 18 and makes each channel (nozzle) independent, the peripheral thick portion 42 to be joined to the frame member 13, and the common liquid chamber 36. An elastic body portion (damper portion) 43 that absorbs the pressure applied is formed.

The liquid chamber partition member 32 is formed by applying a dry film resist on the diaphragm 31 in advance, exposing it using a required mask, and developing it to form a first liquid chamber pattern.
The photosensitive resin layer 45 and the second photosensitive resin layer 46 on which a dry film resist is applied in advance on the nozzle plate 33 side, exposed using a required mask, and developed to form a predetermined liquid chamber pattern are heated. It is joined by crimping.

The nozzle plate 33 has a large number of nozzles 38, which are fine discharge ports for flying ink droplets. The internal shape (inner shape) of this nozzle 38 is
It is formed in a substantially cylindrical shape (or a substantially truncated cone shape). The diameter of the nozzle 38 is about 25 to 35 μm on the ink droplet outlet side.

The ink ejection surface (nozzle surface side) of the nozzle plate 33 is a water-repellent surface 47 which has been subjected to a water-repellent surface treatment as shown in FIG. For example, PTF
Ink physical properties such as E-Ni eutectoid plating, electrodeposition coating of fluororesin, vapor-deposited evaporative fluororesin (for example, pitch fluoride), baking after solvent application of silicon resin or fluorine resin The water-repellent treatment film selected according to the above is provided to stabilize the ink droplet shape and the flying characteristics so that high-quality image quality can be obtained.

The drive unit 1 and the liquid chamber unit 2
After processing and assembling separately, the vibration plate 31 of the liquid chamber unit 2 and the piezoelectric element 12 and the frame member 13 of the drive unit 1 are joined with an adhesive 49.

Then, the substrate 11 is supported and held on a spacer member (head holder) 50 as a head support member, and a head driving I disposed in the spacer member 50 is provided.
C and the electrodes 24 and 25 connected to the piezoelectric elements 12 (drive unit 17) of the drive unit 1
They are connected via PC cables 51,51.

The nozzle cover (head cover) 3
Is formed in a box shape that covers the periphery of the nozzle plate 33 and the side surface of the head, and is bonded to the periphery of the nozzle plate 33 with an adhesive. Further, in order to supply ink from an ink cartridge (not shown) to the liquid chamber, a spacer member 50,
The substrate 11, the frame member 13, and the vibration plate 31 are provided with ink supply holes 52 to 55, respectively.

In the ink jet head thus configured, by applying a drive waveform (pulse voltage of 10 to 50 V) to the drive unit 17 according to the recording signal, a displacement in the stacking direction occurs in the drive unit 17, Diaphragm 31
The pressurized liquid chamber 35 is pressurized through the diaphragm section 34 of the above, and the pressure rises, and ink droplets are ejected from the nozzle 38. At this time, ink flows also in the direction of the ink supply passages 37, 37 leading from the pressurized liquid chamber 35 to the common liquid chamber 36. However, by reducing the cross-sectional area of the ink supply passages 37, 37, the fluid resistance portion is reduced. Function to reduce the flow of ink toward the common liquid chambers 36, 36, thereby preventing a drop in ink ejection efficiency.

Then, with the end of the ejection of the ink droplets, the ink pressure in the pressurized liquid chamber 35 decreases, and a negative pressure is generated in the pressurized liquid chamber 34 due to the inertia of the ink flow and the discharge process of the drive pulse. To the ink filling process. At this time, the ink supplied from the ink tank flows into the common liquid chambers 36, 36, and from the common liquid chambers 36, 36 to the ink supply paths 37, 3.
After that, it is filled into the pressurized liquid chamber 35. Then, the vibration of the ink meniscus surface near the outlet of the nozzle 38 is attenuated,
When the ink is returned to the vicinity of the outlet of the nozzle 38 due to surface tension (refill) and reaches a stable state, the operation shifts to the next ink droplet ejection operation.

Next, a first embodiment of the manufacturing process of the actuator unit according to the present invention will be described with reference to FIG. FIG. 3 is a perspective view for explaining the manufacturing process.

First, a green sheet 60 in which green sheets mainly composed of lead zirconate titanate (PZT), which is a piezoelectric material, and internal electrode layers shown in FIG. As shown in FIG. 2B, two green sheets 60 are positioned at predetermined positions on the main plane 61a of the fired ceramic substrate 61 which will become the head substrate 11, and as shown in FIG. Adhere on 61.

At this time, by forming an adhesive layer on the ceramic substrate 61 in advance, the adhesive force can be increased, and the yield of the process can be improved. Further, by using a paste material containing PZT as a main component as the adhesive layer, it is possible to more easily improve the adhesive strength. Note that the adhesive layer mentioned here is different from the adhesive 14 for joining the frame members 13 shown in FIGS.

Next, as shown in FIG. 4D, the piezoelectric element 63 is obtained by firing the ceramic substrate 61 and the green sheet 60 integrally. After that, the slit processing is performed on the piezoelectric element 63 to form a slit groove 64 reaching the ceramic substrate 61, and the piezoelectric element 12 is divided into a plurality of piezoelectric elements 12.

As described above, by bonding the green sheet as the piezoelectric element to the ceramic substrate after the final firing as the head substrate and integrally firing the same, the insufficient mechanical strength of the piezoelectric element can be compensated by the bonding with the substrate. As a result, warpage during firing of the piezoelectric element and cracking after firing do not occur, and the size of the piezoelectric element can be increased, thereby increasing the speed of the recording apparatus by increasing the number of nozzles.

Here, in the first embodiment described above,
After the ceramic substrate 61 and the green sheet 60 are integrally fired to obtain the piezoelectric element 63 and before slitting (grooving), an electrode layer serving as an end surface electrode can be formed on the side surface of the piezoelectric element 63. . Since the formation of the electrode layer is performed in a state where the electrode layer is bonded to the ceramic substrate, a simple forming method such as printing can be applied, and the working efficiency is improved.

In this case, the main plane 6 of the ceramic substrate 61
After forming an electrode layer on the exposed surfaces (end surface and upper surface) of 1a and the piezoelectric element 63, of the exposed surfaces of the piezoelectric element 63,
Surface parallel to main plane 61a of ceramic substrate 61 (upper surface)
By mechanically grinding, individual electrodes on the ceramic substrate 61 and end electrodes on the side surfaces of the piezoelectric element 63 can be formed more easily.

Next, a second embodiment of the manufacturing process of the actuator unit according to the present invention will be described with reference to FIG. FIG. 3 is a perspective view for explaining the manufacturing process. In this embodiment, a green sheet 6 in which lead zirconate titanate (PZT-based) -based green sheets and internal electrode layers shown in FIG.
And a fired plate material 71 composed of the same main components as the ceramic substrate 61 is formed on the green sheet 60.
Then, as shown in FIG. 3B, the laminate 72 is positioned at a predetermined position on the main plane 61a of the ceramic substrate 61 after the final firing as the head substrate 11, and as shown in FIG. On the ceramic substrate 61. afterwards,
Ceramic substrate 61, green sheet 60 and plate material 72
Is fired integrally. The subsequent steps are the same as in the first embodiment described above.

As described above, the same material (the ceramic substrate 6) is formed on the upper and lower surfaces of the green sheet 60 mainly composed of the piezoelectric material.
1 and the plate material 71) are bonded together, so that the shrinkage of the green sheet 60 in the direction parallel to the main plane of the ceramic substrate 61 is suppressed at the time of firing, and variation in the dimensional accuracy of the piezoelectric element 63 is reduced. I do.

[0037]

As described above, according to the method of manufacturing an ink jet head according to the present invention, a green sheet containing a piezoelectric material as a main component is bonded onto a main plane of a ceramic substrate after final firing to integrally fire. So that
It is possible to prevent the piezoelectric element from being warped or cracked at the time of firing and to increase the size.

In this case, by bonding a layer member made of the same material as the ceramic substrate on the green sheet and then integrally firing the same, it is possible to reduce variations in dimensional accuracy. Further, by forming an adhesive layer between the ceramic substrate and / or the green sheet and the layer member made of the same material as the ceramic substrate, the adhesive force is increased and the yield is improved. By using a paste-like material mainly composed of the same material as the piezoelectric element as the adhesive layer, the adhesive strength can be more easily improved.

Further, after the ceramic substrate and the green sheet are integrally fired, an electrode layer is formed on the surface of the exposed surface of the piezoelectric element perpendicular to the main plane of the ceramic substrate, so that the end surface electrode can be formed by a simple method such as printing. Can be formed,
Furthermore, after forming the electrode layer, by grinding a surface parallel to the main plane of the ceramic substrate in the exposed surface of the piezoelectric element and removing the electrode layer on the parallel surface, the individual electrodes can be easily formed. Can be formed.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an inkjet head to which the present invention has been applied.

FIG. 2 is an enlarged sectional view of a main part of the head in a direction orthogonal to a channel direction.

FIG. 3 is an enlarged cross-sectional view of a main part of the head in a channel direction.

FIG. 4 shows a first step of the manufacturing process of the actuator according to the present invention.
Explanatory perspective view for explaining an embodiment

FIG. 5 shows a second step of the manufacturing process of the actuator according to the present invention.
Explanatory perspective view for explaining an embodiment

FIG. 6 is an explanatory perspective view illustrating a manufacturing process of a conventional inkjet head.

FIG. 7 is an explanatory view illustrating a manufacturing process of a conventional inkjet head.

[Explanation of symbols]

1 drive unit, 2 liquid chamber unit, 3 frame
11: head substrate, 12: piezoelectric element, 17: drive unit, 1
8 non-driving part, 31 diaphragm, 33 nozzle plate,
34 ... diaphragm part, 40 ... island-shaped convex part, 41 ... beam part,
Reference numeral 42 denotes a peripheral thick portion, 43 denotes a damper portion, 60 denotes a green sheet, 61 denotes a ceramic substrate, 63 denotes a piezoelectric element after firing, 64 denotes a slit groove, and 71 denotes a plate material.

Claims (6)

[Claims] 1. A method of manufacturing an ink jet head for dividing a piezoelectric element bonded to a ceramic substrate into a plurality of piezoelectric elements by subjecting the piezoelectric element to slitting, wherein the piezoelectric material is mainly contained on a main plane of the ceramic substrate after final firing. A method of manufacturing an ink jet head, comprising: bonding green sheets to be integrally fired. 2. The method for manufacturing an ink jet head according to claim 1, wherein a layer member made of the same material as that of the ceramic substrate is bonded onto the green sheet and then integrally fired. 3. The method for manufacturing an ink jet head according to claim 1, wherein the ceramic substrate and / or
Alternatively, a method for manufacturing an ink jet head, comprising forming an adhesive layer between a layer member made of the same material as a ceramic substrate and a green sheet. 4. The method for manufacturing an ink jet head according to claim 3, wherein the adhesive layer is made of a paste-like material mainly composed of the same material as the piezoelectric element. 5. The method for manufacturing an ink jet head according to claim 1, wherein the ceramic substrate and the green sheet are integrally fired, and the main surface of the ceramic substrate among the exposed surfaces of the piezoelectric element is formed. A method for manufacturing an ink jet head, comprising forming an electrode layer on a vertical surface. 6. The method of manufacturing an ink jet head according to claim 5, wherein after forming the electrode layer, a surface parallel to a main plane of the ceramic substrate is ground out of an exposed surface of the piezoelectric element. A method for manufacturing an ink jet head, comprising: removing an electrode layer on a flat surface.