JPH0781070A - Production of ink jet head - Google Patents

Abstract

PURPOSE:To produce an ink jet head enhanced in capacity by eliminating the adhesive layer present between a vibration plate and a piezoelectric element. CONSTITUTION:In the production of an ink jet head having a passage plate 21, the vibration plate 25 composed of a Si-based material bonded to the passage plate 1 and an electromechanical conversion element having upper and lower electrodes 27, 28 provided to the upper and rear surfaces thereof and attached on the vibration plate 25, the lower electrode 28, the electromechanical conversion element 26 and the upper electrode 27 are formed by printing. The thickness of the lower electrode 28 is set to 0.5-20mum and the surface roughness thereof is set to the thickness thereof or thinner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head applied to an ink jet printer, and more particularly to a method of manufacturing an ink jet head in which Si having excellent workability is selected as a member of the head.

[0002]

2. Description of the Related Art Ink jet printers are of a type in which fine particles of ink are directly blown onto a print medium from a head which is not in contact with the print medium for recording, and there are few restrictions on the print medium and colorization is easily realized. It has the feature of being capable of recording, and has the features of high-speed recording and low noise.

FIG. 7 shows the structure of a general ink jet printer which has been put into practical use. In the figure, 1 is an inkjet head, 2 is a platen, and 3 is an ink tank. The inkjet head 1 is mounted on a carrier 6 which is guided by guides 4 and 5 and reciprocates in a direction perpendicular to the plane of the drawing, faces the platen 2, and moves along with the carrier 6 along the platen 2. Ink is supplied to the inkjet head 1 from an ink tank 3 which is connected to the inkjet head 1 via an ink tube 7.

The structure of the ink jet head 1 is as shown in the side view of FIG. 8, and the ink jet head 1 is a piezoelectric device having a flow path plate 8, a vibration plate 9, and an upper electrode 10 and a lower electrode 11 on the front and back surfaces. Element (electromechanical conversion element) 12
It consists of and.

The flow path plate 8 includes a pressure chamber 13 and the pressure chamber 13.
A nozzle 14 that communicates with the head substrate surface (the lower surface in FIG. 8) and that communicates with the pressure chamber 13, and an ink supply path 15 that receives ink through the ink tube 7. The vibration plate 9 is joined to the back surface of the flow path plate 8 to cover the pressure chamber 13 and the ink supply path 15. Piezoelectric element 12
Is the pressure chamber 13 on the vibration plate 9 with the lower electrode 11 facing downward.
It is joined to the position opposite to. The conventional manufacturing method of the inkjet head 1 is as follows.

As a method of forming a pressure chamber or the like on the flow path plate, a method of engraving grooves by etching on a substrate such as stainless steel or glass is used. Then, the flow path plate 8 thus formed by etching is overlapped with the vibration plate 9 made of stainless steel or the like, and bonded by a method such as diffusion bonding. Furthermore, the nozzle surface is wrapped to ensure the smoothness of the nozzle surface.

Next, the piezoelectric element 12 is bonded to the portion of the upper surface of the vibrating plate 9 facing the pressure chamber 13 with an adhesive as a drive unit for generating pressure in the pressure chamber. The signal line for applying a voltage to the piezoelectric element 12 is connected by a technique such as soldering or electrode crimping.

Printing by the ink jet head 1 is performed in the following procedure. That is, upon printing, a voltage is applied for a predetermined time to a predetermined piezoelectric element 12 of the inkjet head 1 that moves along the platen as described above. As a result, the piezoelectric element 12 contracts in the width direction, and as a result, the diaphragm 9 bends toward the pressure chamber 13.

Due to this bending, pressure is generated inside the pressure chamber, and the particles are ejected from the nozzle 14. The particle velocity in this case is usually 3 to 10 m / s, and the applied voltage required therefor is 40 to 100V.

[0010]

As described above, conventionally, the piezoelectric element is mounted on the diaphragm by bonding with an adhesive. Therefore, there is a problem that the manufacturing cost is high and the efficiency of particle formation is low because the adhesive layer is interposed between the piezoelectric element and the vibration plate. Moreover, in the conventional method,
Due to handling problems, there are limitations on the thickness and dimensions of the piezoelectric element, and there is also the problem that the thickness and dimensions required to increase the particle formation efficiency cannot be freely selected.

Furthermore, in the conventional method, in the case of a multi-nozzle head having a plurality of nozzles, the number of piezoelectric elements is 24 to 24.
Since 64 piezoelectric elements need to be bonded one by one, the manufacturing cost and yield are poor, and there are problems such as large variations in characteristics between nozzles.

It is an object of the present invention to provide a method of manufacturing an ink jet head which can solve various problems due to the influence of an adhesive layer existing between a vibration plate and a piezoelectric element.

[0013]

In order to achieve the above object, the present invention provides a flow channel plate having one or more nozzles, a pressure chamber communicating with the nozzle, and an ink passage for supplying ink to the pressure chamber. And a vibration plate made of a Si-based material bonded on the flow path plate so as to cover the pressure chamber and the ink supply path, an upper electrode and a lower electrode on the front and back surfaces, and the lower electrode on the vibration plate. An attached electromechanical conversion element,
In the method of manufacturing an ink jet head having the above-mentioned, the lower electrode is formed by printing a paste-like material having a thickness of 0.5 to 20 μm, and then an electromechanical conversion element of the electromechanical conversion element and the upper electrode formed thereon is formed. A constitution (first constitution) is characterized in that the element is formed by printing a paste-like material and then firing it at a temperature suitable for obtaining a piezoelectric effect.

In the ink jet head having the first structure, the surface roughness of the lower electrode is equal to or less than the thickness of the lower electrode (second structure).

In the method of manufacturing an ink jet head having the above-mentioned first structure or second structure, the lower electrode is printed and dried on the first lower electrode, and then the second lower electrode is printed and baked. It is configured to be formed by superimposing two layers obtained by (3rd configuration).

[0016]

Since the electromechanical conversion element is formed on the Si-based diaphragm by printing, it can be easily formed at low cost. Further, the desired thickness, size, and shape can be formed with high reliability, and a piezoelectric element layer having a thickness suitable for the thickness of the diaphragm can be realized. The head can be realized. Further, the vibrating plate and the electrode, and the electrode and the electromechanical conversion element are directly joined by printing and firing, and the conventional adhesive layer is eliminated.

If the lower electrode is thin, or if the surface roughness of the lower electrode is rough, the lead oxide component in the piezoelectric element layer moves to the Si diaphragm side, and becomes a vitrified lead on the Si surface to form the piezoelectric element. Will be a problem in securing the characteristics. By setting the surface roughness of the lower electrode to be equal to or less than its thickness, the crystallinity of the piezoelectric element could be secured. Further, when the thickness of the lower electrode is 0.5 to 20 μm, the driving voltage can be effectively reduced.

[0018]

Embodiments of the present invention will be described below with reference to FIGS.

Prior to the description of specific embodiments, the outline of the present invention will be described first. In the present invention, the lower electrode is formed by printing a paste material having a thickness of 0.5 to 20 μm, and the electromechanical conversion element and the electromechanical conversion element of the upper electrode formed on the lower electrode are formed by the paste material. Is printed and then baked at a temperature suitable for obtaining a piezoelectric effect.

As this printing method, there is a method of applying the above-mentioned paste material containing a binder necessary for printing by screen printing or applying with a dispenser. Another method is to use letterpress and intaglio. FIG. 1 is an explanatory view of the principle of the printing method of the present invention, showing a procedure of forming a lower electrode 102, a piezoelectric element 103 which is an electromechanical conversion element, and an upper electrode 104 on a vibration plate 101 by screen printing.

FIG. 1A shows a lower electrode 1 on a vibrating plate 101.
02 shows a state in which the piezoelectric element 103 is formed thereon, and FIG. 1C shows a state in which the upper electrode 104 is further formed thereon. In addition, FIG. 1D shows the printing plate 105 and the squeegee 10.
6 shows a paste-like material application process using No. 6.

The electrode and the piezoelectric element layer are then fired by heating at a high temperature, whereby the piezoelectric element layer becomes a perovskite structure having a piezoelectric internal crystal structure,
Further, the lower electrode on the side of the vibration plate can have a function as an electrode and a function of joining the piezoelectric element layer and the vibration plate.

In the screen printing method, a printing plate 105 having a shape required as a piezoelectric element is formed, and the printing plate 10 is formed.
5 is overlaid on the vibration plate 101, and a paste-like material is printed and fired. Further, the electrodes can be formed by the same method for both the lower electrode and the upper electrode. Piezoelectric materials include PMN-PT, PNN-, which is a titanate value-based ceramic, PZT (lead zirconate titanate), and a compound having a perovskite structure added to this system.
Materials such as PTPZ can also be used. The electrode material is Ag, P
A metal material such as t is suitable.

As described above, according to this method, since the electrodes and the piezoelectric layer are directly formed on the diaphragm, the manufacturability is excellent, and the desired thickness, size, and shape can be formed with high reliability. You can Moreover, since the thickness of the piezoelectric element layer formed by controlling the thickness of the printing plate can be freely set within the range of 2 to 200 μm, a piezoelectric element layer suitable for the thickness of the diaphragm can be obtained. . Therefore, particles can be ejected from the nozzle with high particle formation efficiency and low driving voltage.

Further, since the vibrating plate and the electrode and the electrode and the piezoelectric element are directly joined by printing and firing, the conventional adhesive layer is eliminated, and the particle formation efficiency is further improved.

When the piezoelectric element is formed by screen printing, the thickness of the piezoelectric layer that can be favorably formed is 5 to 100 μm.
The range of m is most suitable. Further, when the piezoelectric element layer is formed on the Si vibration plate, if the lower electrode is thin, the crystallinity of the piezoelectric element is poor and desired characteristics cannot be obtained. Therefore, it is necessary to set the thickness of the lower electrode appropriately. .

Next, various embodiments of the present invention will be described.

2 to 4 show a first embodiment.

FIG. 2 is an explanatory view of the manufacturing process of the ink jet head of this embodiment. As shown in FIG. 2 (C) showing the head completed state, the ink jet head 20 has a pressure chamber 22, nozzles 23 and inks as in the conventional case. A flow path plate 21 provided with a supply path 24, a pressure chamber 22, a nozzle 23, and
Si vibrating plate 25 bonded to cover the ink supply path 24
And a piezoelectric element (electromechanical conversion element) 26 provided with an upper electrode 27 and a lower electrode 28 on the front surface and the back surface and attached at a position facing the pressure chamber 22 on the vibration plate 25.

The size of the outlet of the nozzle 23 is 50 μm in width.
m, depth 30 μm, size of pressure chamber 22 is 1 × 2 mm
Is. The flow path plate 21 and the diaphragm 25 are joined by an adhesive. The lower electrode 28, the piezoelectric element 26, and the upper electrode 27 are formed on the vibrating plate 25 by the following procedure.

A vibrating plate 25 is overlaid with a printing plate having an opening mesh of 1 × 2 mm, and an electrode material containing Ag as a main component is mixed with an organic resin binder and an organic solvent to have a viscosity of 2000 cP.
The paste prepared in step 1 was printed with a squeegee to a thickness of 5 μm and left at room temperature for 10 minutes to reduce the surface roughness P _max . As a result, the lower electrode 28 is formed as shown in FIG.

Further, a paste containing a piezoelectric material is printed thereon with a thickness of 50 μm using a printing plate of the same shape to form a piezoelectric element 26 as shown in FIG. 2 (B). The piezoelectric material used was one in which PZT was powdered and mixed with an organic resin binder to adjust the viscosity to 3000 cP.
Further, the same material as the lower electrode is printed thereon by 3 μm, dried and processed to form the inkjet head 20 shown in FIG. 2C. FIG. 3 is a block diagram showing these processes.

The entire head manufactured in this way is
Heat in a heating furnace at 100 ° C for 10 minutes, then 1000 ° C
The crystallinity of the piezoelectric element obtained by firing for 1 hour in the above heating furnace was evaluated by XRD, and as a result, 97% of perovskite was obtained. FIG. 4 shows this result in comparison with the conventional one. FIG. 4 (A) shows the case of the conventional method, and FIG. 4 (B) shows the case of the present invention.

As a result of injecting ink into this prototype head and applying a voltage of 50 V to the electrodes, it was possible to stably eject the ink from the nozzle at a speed of 7 m / s. For comparison, when a similar piezoelectric element was formed with a lower electrode having a thickness of 0.4 μm, the crystallinity was 20% or less, and the driving voltage required to obtain the characteristics was 250V or more. .

FIG. 5 shows a second embodiment.

In this example, as shown in FIG. 5, the first lower electrode 32 is formed on the Si vibration plate 31 by printing the Ag / Pd mixed material of the lower electrode material to a thickness of 4 μm and drying it. Then, a second lower electrode 33 having a thickness of 4 μm was formed by printing and drying to form a lower electrode. PNN-PTPZ was printed on the lower electrode to a thickness of 20 μm by a screen printing method to form a piezoelectric element (electromechanical conversion element) 34.

This head was heated at 100 ° C. for 10 minutes and then baked at 900 ° C. for 1 hour. Then, the piezoelectric element 34
An upper electrode 35 of aluminum was formed on the surface of by using a sputtering method. As a result of evaluating the crystallinity of the piezoelectric element thus constituted by XRD, a crystallinity of 98% was obtained. When the characteristics of the head were examined, a particle velocity of 7 m / s was obtained at 60V.

FIG. 6 shows a third embodiment.

6A and 6B are structural explanatory views of the ink jet head of this example, FIG. 6A is a front view seen from the piezoelectric element side, and FIG. 6B is a side view. This inkjet head 4
Reference numeral 0 denotes a nozzle plate 42 having a plurality of nozzles 41, a pressure chamber 43 for each nozzle 41, and an ink supply path (not shown).
Flow path plate 44 in which the diaphragm is formed, and diaphragm 4 made of Si material
5, piezoelectric elements (electromechanical conversion elements) 46 corresponding to the pressure chambers 43 are formed on the vibration plate 45 by printing.

The number of nozzles 41 is 64, and the corresponding number of pressure chambers 43 are also arranged. The size of one of the pressure chambers 43 is 0.5 × 1.0 mm. In forming the piezoelectric element, first, a screen printing plate having an opening mesh corresponding to the entire 64 pressure chambers is used on the vibrating plate 45, and an electrode material containing Ag and Pd as a main component is combined with an organic resin binder. A paste adjusted to a viscosity of 2000 cP mixed with an organic solvent was printed with a squeegee to a thickness of 5 μm to form a lower electrode 47.

Then, the surface roughness is left to stand and dried to 1 μm.
Then, the piezoelectric element layer is printed with a thickness of 40 μm using a printing plate having a plurality of opening meshes corresponding to the pressure chambers. Further, an electrode material similar to the lower electrode was printed on each piezoelectric element layer with a thickness of 3 μm. The head manufactured in this manner was heated at 100 ° C. for 10 minutes and then baked at 1000 ° C. for 2 hours. As a result of evaluating the crystallinity of this piezoelectric element, a crystallinity of 97% was obtained.

As a result of injecting ink into this head and applying a voltage pulse to each electrode, ink particles were ejected from each nozzle 41 at an average speed of 7 m / s at a drive voltage of 40V. The variation in particle velocity of each nozzle was ± 10% or less.

For comparison, according to the conventional method, a size of 0.5 is used.
A head was manufactured by adhering piezoelectric elements each having a size of × 1 mm and a thickness of 100 μm one by one with an epoxy adhesive, and as a result of investigating the characteristics of the head, a high driving voltage of 150 V resulted in an average particle velocity of 7 m s was obtained. Also,
The variation in the speed of each nozzle was ± 30% or more.

Further, when the thickness of the lower electrode is 25 μm or more, 97% or more of crystallinity can be obtained, but since it becomes difficult to transmit the displacement of the piezoelectric element to the vibration plate, the efficiency of particle formation is lowered, which is necessary. There is a problem that the driving voltage becomes high. As a result of examination, it was found that the lower electrode thickness is preferably 0.5 to 20 μm. Further, the surface roughness of the lower electrode needs to be equal to or less than the thickness of the lower electrode.

[0045]

As described above, according to the present invention, S
Since a good piezoelectric element can be easily formed on the i diaphragm, a low-cost inkjet head with excellent manufacturability can be provided. Further, the desired thickness, size, and shape can be formed with high reliability, and a piezoelectric element having a thickness suitable for the thickness of the diaphragm can be formed.
It is possible to realize an inkjet head having high particle formation efficiency and low driving voltage.

Further, since the vibrating plate and the electrode and the electrode and the piezoelectric element are directly joined by printing and firing, there can be provided an ink jet head which does not have an adhesive layer as in the prior art and which has a high particle formation efficiency. Further, when the thickness of the lower electrode is 0.5 to 20 μm, the driving voltage can be effectively reduced, and when the surface roughness of the lower electrode is equal to or less than that thickness, it is effective in securing the crystallinity of the piezoelectric element.

In the above description, the case where Si is used as the material of the vibrating plate has been described, but a material other than Si that moves the components in the piezoelectric material by contact with the piezoelectric material, such as glass. , that there are equally effective also SiO ₂ film or the like is not even mentioned.

[Brief description of drawings]

1A and 1B are explanatory views of the principle of the printing method of the present invention. FIG. 1A shows a lower electrode formation state, FIG. 1B shows a piezoelectric element formation state, and FIG. 1C shows an upper electrode formation state. 1D shows the printing procedure.

2A and 2B are explanatory views of the manufacturing process of the inkjet head according to the first embodiment of the present invention, in which FIG. 2A shows a lower electrode formation state, FIG. 2B shows a piezoelectric element formation state, and FIG. C) shows the completed state of each head.

FIG. 3 is a processing block diagram of the inkjet head according to the first embodiment of the present invention.

4A and 4B are explanatory diagrams of crystallinity of the piezoelectric element according to the first embodiment of the present invention. FIG. 4A shows the conventional one and FIG. 4B shows the present invention.

FIG. 5 is a structural explanatory view of an inkjet head according to a second embodiment of the present invention.

6A and 6B are structural explanatory views of an ink jet head of a third embodiment of the present invention, FIG. 6A is a front view and FIG. 6B is a side view.

FIG. 7 is a side view showing an outline of the structure of an inkjet printer.

8 is a side view showing the details of the structure of the inkjet head of FIG. 7. FIG.

[Explanation of symbols]

20, 40 Inkjet head 21, 44 Flow path plate 22, 43 Pressure chamber 23, 41 Nozzle 24 Ink supply path 25, 45, 101 Vibration plate 26, 34, 46, 103 Piezoelectric element (electromechanical conversion element) 27, 35, 104 upper electrode 28, 47, 102 lower electrode 32 first lower electrode 33 second lower electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroki Kitagawa, 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa, Fujitsu Limited Fujitsu Limited (72) Yuko Miyake 1015, Kamedota, Nakahara-ku, Kawasaki, Kanagawa Prefecture, Fujitsu Limited

Claims (3)

[Claims] 1. A flow channel plate having one or more nozzles, a pressure chamber communicating with the nozzle, and an ink supply path for supplying ink to the pressure chamber, and the pressure chamber and the ink on the flow channel plate. An ink jet having a vibration plate made of a Si-based material bonded to cover a supply path, and an electromechanical conversion element having an upper electrode and a lower electrode on a front surface and a back surface and attached on the vibration plate via the lower electrode. In the method of manufacturing a head, the lower electrode is formed by printing a paste-like material having a thickness of 0.5 to 20 μm, and an electromechanical conversion element formed on the lower electrode and an electromechanical conversion element of the upper electrode are A method for manufacturing an inkjet head, which is formed by printing a paste-like material and then firing it at a temperature suitable for obtaining a piezoelectric effect. 2. The method for manufacturing an inkjet head according to claim 1, wherein the surface roughness of the lower electrode is not more than the thickness of the lower electrode. 3. The lower electrode is formed by superposing two layers obtained by printing and drying the first lower electrode and then printing and firing the second lower electrode. The method for manufacturing an inkjet head according to claim 1 or 2.