JP2990479B2 - Ink jet head and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ink jet head applied to an inkjet printer, more particularly to a method of manufacturing an ink jet head and its selected the Si which is excellent in workability as members of the head.

[0002]

2. Description of the Related Art An ink jet printer is a system in which fine particles of ink are directly sprayed onto a print medium from a head which is not in contact with the print medium and recording is performed. It has the features of being able to do so, and has the features of high-speed recording and low noise.

FIG. 7 shows the structure of a general inkjet printer which has been put to practical use. In the figure, 1 is an inkjet head, 2 is a platen, and 3 is an ink tank. The ink jet head 1 is mounted on a carrier 6 that 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. The ink supply to the inkjet head 1 is performed from an ink tank 3 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 has a flow path plate 8, a vibration plate 9, and a piezoelectric plate having an upper electrode 10 and a lower electrode 11 on the front and back surfaces. Element (electromechanical conversion element) 12
It is composed of

The flow path plate 8 includes a pressure chamber 13 and the pressure chamber 13.
A nozzle 14 that communicates with the nozzle and opens on the surface of the head substrate (the lower surface in FIG. 8), and an ink supply passage 15 that communicates with the pressure chamber 13 and receives supply of ink via the ink tube 7. The vibration plate 9 is joined to the back surface of the flow path plate 8 and covers the pressure chamber 13 and the ink supply path 15. Piezoelectric element 12
Are the pressure chambers 13 on the diaphragm 9 with the lower electrode 11 on the lower side.
Are joined at a position opposite to. The conventional manufacturing method of the ink jet head 1 is as follows.

As a method of forming a pressure chamber or the like in a flow path plate, a method of forming a groove by etching a substrate of stainless steel, glass, or the like is used. Then, the flow path plate 8 formed by etching as described above is overlapped with the vibration plate 9 formed of stainless steel or the like, and joined by a technique such as diffusion bonding. Further, the nozzle surface is wrapped to ensure smoothness of the nozzle surface.

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

The printing by the ink jet head 1 is performed in the following procedure. That is, at the time of printing, a voltage is applied to the predetermined piezoelectric element 12 of the inkjet head 1 that moves along the platen at a predetermined time as described above for a predetermined time. 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 particles are ejected from the nozzle 14. In this case, the speed of the particles is usually required to be 3 to 10 m / s, and the applied voltage required for that is 40 to 100 V.

[0010]

As described above, conventionally, the attachment of the piezoelectric element to the vibration plate has been performed 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. Also, in the conventional method,
Due to handling problems, the thickness and dimensions of the piezoelectric element are limited, and there has been a problem that the thickness and dimensions required for increasing the particleization 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
Since it is necessary to bond these piezoelectric elements one by one to 64 pieces, there are problems such as a low manufacturing cost and a low yield, and large variations in characteristics among the nozzles.

[0012] The present invention aims at providing a method of fabricating an ink jet head and its capable of solving various problems due to the influence of the adhesive layer between the vibration plate and the piezoelectric element.

[0013]

In order to achieve the above object, the present invention provides one or more nozzles, a pressure chamber connected to the nozzle, and an ink supply path for supplying ink to the pressure chamber. a channel plate having the pressure chamber in the flow path plate, a diaphragm of Si material bonded over the ink supply path,
An upper electrode and a lower electrode on the front surface and the rear surface, including a lead-based mounted via the bottom electrode on said diaphragm pressure
In the ink jet head, the thickness of the lower electrode is formed by printing a paste-like material of which has a photoelectric element
Consisting of 0.5 to 20 μm electrodes and provided on it
Piezoelectric element containing lead-based, lead-based piezoelectric element in upper electrode
The piezoelectric element prints the paste-like material and fires it.
And a perovskite structure (first configuration).

Further, in the ink jet head having the first configuration, the surface roughness of the lower electrode is equal to or less than the thickness of the lower electrode (second configuration). In addition, the ink-jet recording device according to the first configuration or the second configuration.
In the jet head, the lower electrode is connected to the first lower electrode.
That the second lower electrode has a two-layer superposed structure.
This is a characteristic configuration (third configuration).

In the present invention, one or more nozzles,
Pressure chamber with which nozzle communicates, and ink supply to this pressure chamber
A flow path plate having an ink supply path,
Si material bonded to cover the pressure chamber and the ink supply path
And upper and lower electrodes on the front and back surfaces
Mounted on the diaphragm via the lower electrode
Ink jet head having lead-based piezoelectric element
In the manufacturing method, the lower electrode may have a thickness of 0.5 to 20.
μm paste-like material is printed and then
Lead-containing piezoelectric element formed on the top electrode
A piezoelectric element containing lead is printed on a paste-like material.
Afterwards, by firing at a temperature suitable for obtaining the piezoelectric effect
(Fourth configuration)
You. Further, the production of the ink jet head of the fourth configuration described above.
In the fabrication method, the surface roughness of the lower electrode is
A configuration (fifth configuration) characterized in that the thickness is not more than
I do. In addition, the ink of the above-described fourth configuration or the fifth configuration may be used.
In the jet head, the lower electrode is a first lower electrode
After printing and drying, the second lower electrode is printed and fired.
Formed by superposition of two layers obtained by
(Sixth configuration).

[0016]

[Function] Piezoelectric element containing lead on a diaphragm made of Si material
Since the child is formed by printing, it can be easily formed at low cost. In addition, 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. A head can be realized. further,
The diaphragm and the electrode, and the electrode and the electromechanical transducer are directly joined by printing and baking, eliminating the conventional adhesive layer, so that the particle formation efficiency is further improved.

When the lower electrode is thin or 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 lead vitrified on the Si surface to form the piezoelectric element. Problem in securing the characteristics of 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. When the thickness of the lower electrode is 0.5 to 20 μm, the driving voltage can be effectively reduced.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment 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-like material having a thickness of 0.5 to 20 μm, and then the electromechanical transducer formed thereon and the electromechanical transducer in the upper electrode are replaced with the paste-like material. Is formed by firing at a temperature suitable for obtaining a piezoelectric effect after printing.

As a printing method, there is a method of applying the above paste-like material containing a binder necessary for printing by screen printing or by using a dispenser. There are other methods that use letterpress and intaglio. FIG. 1 is a view for explaining the principle of the printing method of the present invention, and shows a procedure for forming a lower electrode 102, a piezoelectric element 103 serving as an electromechanical transducer, and an upper electrode 104 on a vibration plate 101 by screen printing.

FIG. 1A shows a lower electrode 1 on a diaphragm 101.
FIG. 1B 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. FIG. 1D shows the printing plate 105 and the squeegee 10.
6 shows a paste-like material application step using No. 6.

The electrodes and the piezoelectric element layer are then fired by heating at a high temperature. As a result, the piezoelectric element layer has a perovskite structure in which the internal crystal structure has piezoelectricity.
Further, the lower electrode on the vibration plate side can have a function as an electrode and a function of bonding the piezoelectric element layer and the vibration plate.

In the screen printing method, a printing plate 105 corresponding to a shape required as a piezoelectric element is formed, and the printing plate 105 is formed.
5 is superimposed on the vibration plate 101, and the paste material is printed and fired. In addition, both the lower electrode and the upper electrode can be formed by the same method. Examples of the piezoelectric material include PMN-PT, PNN-, which include a titanate-based ceramic, PZT (lead zirconate titanate), and a perovskite structure compound added to this system.
Materials such as PTPZ can also be used. The material of the electrode is Ag, P
Metal materials such as t are suitable.

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

Further, since the vibration plate and the electrode, and the electrode and the piezoelectric element are directly bonded 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 formed well is 5 to 100 μm.
The range of m is most suitable. When a piezoelectric element layer is formed on a Si diaphragm, 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 appropriately set the thickness and the like of the lower electrode. .

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

FIGS. 2 to 4 show a first embodiment.

FIG. 2 is an explanatory view of a manufacturing process of the ink jet head of this embodiment. As shown in FIG. 2C showing a completed state of the ink jet head, the ink jet head 20 has a pressure chamber 22, a nozzle 23, an ink A flow path plate 21 having a supply path 24, and a pressure chamber 22, a nozzle 23,
Si diaphragm 25 bonded over ink supply path 24
And a piezoelectric element (electromechanical transducer) 26 provided with an upper electrode 27 and a lower electrode 28 on the front and back surfaces and mounted 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
It is. The joining of the flow path plate 21 and the vibration plate 25 is performed with an adhesive. The formation of the lower electrode 28, the piezoelectric element 26, and the upper electrode 27 on the diaphragm 25 is performed in the following procedure.

A printing plate having an opening mesh of 1 × 2 mm is overlapped on the vibration plate 25, and an electrode material containing Ag as a main component is mixed with an organic resin binder and an organic solvent to give a viscosity of 2,000 cP.
Was adjusted to a thickness of 5 μm using a squeegee, and left at room temperature for 10 minutes so that the surface roughness P _max was reduced. Thus, 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 by using a printing plate of the same shape to form a piezoelectric element 26 as shown in FIG. 2B. As the piezoelectric material, a material in which PZT was powdered and an organic resin binder was mixed to adjust the viscosity to 3000 cP was used.
Further, the same material as that of the lower electrode is printed thereon at 3 μm, dried and processed to form the ink jet head 20 shown in FIG. 2C. FIG. 3 is a block diagram showing these processes.

The whole prototype head thus manufactured is
Heat in a heating furnace at 100 ° C for 10 minutes, and further heat at 1000 ° C.
As a result of evaluating the crystallinity of the piezoelectric element obtained by baking in a heating furnace for 1 hour by XRD, a perovskite of 97% was obtained. FIG. 4 shows this result in comparison with the conventional case. FIG. 4A shows the case of the conventional method, and FIG. 4B shows the case of the present invention.

The ink was injected into this prototype head, and a voltage of 50 V was applied to the electrodes. As a result, the ink could be stably ejected 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 250 V or more. .

FIG. 5 shows a second embodiment.

In this embodiment, as shown in FIG. 5, a first lower electrode 32 is formed by printing and drying a 4 μm thick Ag / Pd mixed material of a lower electrode material on a Si diaphragm 31. 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 transducer) 34.

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

FIG. 6 shows a third embodiment.

FIG. 6 is an explanatory view of the structure of the ink jet head of this embodiment. FIG. 6 (A) is a front view as seen from the piezoelectric element side, and FIG. 6 (B) is a side view. This inkjet head 4
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).
Plate 44 in which is formed, and diaphragm 4 made of Si material
The piezoelectric element (electromechanical conversion element) 46 corresponding to each pressure chamber 43 is formed on the vibration plate 45 by printing.

The number of the nozzles 41 is 64, and the pressure chambers 43 corresponding thereto are arranged in the same number. One size of the pressure chamber 43 is 0.5 × 1.0 mm. In forming the piezoelectric element, first, a screen printing plate having an opening mesh corresponding to the entirety of the 64 pressure chambers is used on the vibration plate 45, and an electrode material mainly composed of Ag and Pd is combined with an organic resin binder. A paste mixed with an organic solvent and adjusted to a viscosity of 2000 cP was printed with a squeegee to a thickness of 5 μm to form a lower electrode 47.

Then, the surface roughness was allowed to stand and dried to 1 μm.
m, and a piezoelectric element layer is printed thereon with a thickness of 40 μm using a printing plate having a plurality of opening meshes corresponding to the respective pressure chambers. Further, the same electrode material as the lower electrode was printed on each piezoelectric element layer at a thickness of 3 μm. The head thus manufactured was heated at 100 ° C. for 10 minutes, and further baked at 1000 ° C. for 2 hours. As a result of evaluating the crystallinity of this piezoelectric element, 97% crystallinity 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 a driving voltage of 40 V at an average speed of 7 m / s. The variation in the particle velocity of each nozzle was ± 10% or less.

For comparison, according to the conventional method, a size of 0.5
A piezoelectric element having a size of 1 mm and a thickness of 100 μm was bonded one by one with an epoxy-based adhesive to produce a head, and the characteristics of the head were examined. s was obtained. Also,
The variation in the speed of each nozzle was ± 30% or more.

When the thickness of the lower electrode is 25 μm or more, crystallinity of 97% or more can be obtained. However, since it is difficult to transmit the displacement of the piezoelectric element to the vibration plate, the particle formation efficiency is reduced, and There is a problem that the driving voltage becomes high. As a result of the study, it was found that the thickness of the lower electrode is preferably 0.5 to 20 μm. Further, it is necessary that the surface roughness of the lower electrode is not more 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-vibration plate, a low-cost inkjet head with excellent manufacturability can be provided. In addition, a 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.
An ink jet head having a high particleization efficiency and a low driving voltage can be realized.

Further, since the vibration 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 has a high particle formation efficiency. 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 the thickness, it is effective in securing the crystallinity of the piezoelectric element.

[0047]

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams illustrating the principle of a printing method according to the present invention. FIG. 1A shows a state in which a lower electrode is formed, FIG. 1B shows a state in which a piezoelectric element is formed, and FIG. 1 (D) shows a printing procedure.

FIGS. 2A and 2B are explanatory diagrams of a manufacturing process of the ink jet head according to the first embodiment of the present invention. FIG. 2A shows a state of forming a lower electrode, FIG. C) shows the completed state of the head, respectively.

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

FIGS. 4A and 4B are explanatory diagrams of the 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 one according to the present invention.

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

FIG. 6 is a structural explanatory view of an ink jet head according to a third embodiment of the present invention, wherein FIG. 6 (A) is a front view and FIG. 6 (B) is a side view.

FIG. 7 is a side view showing the outline of the structure of the ink jet printer.

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

[Explanation of symbols]

20, 40 Ink jet 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

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroki Kitagawa 1015 Uedanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Yuko 1015 Kamikodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited ( 56) References JP-A-5-286131 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2/16 B41J 2/045 B41J 2/055

Claims (6)

(57) [Claims] 1. A flow path plate having one or more nozzles, a pressure chamber connected to the nozzles, and an ink supply path for supplying ink to the pressure chambers, and the pressure chamber and the ink on the flow path plate. A diaphragm made of a Si material joined to cover the supply path, and a pressure containing a lead-based material provided with an upper electrode and a lower electrode on the front and back surfaces, and mounted on the diaphragm via the lower electrode .
In the ink-jet head having a conductive element, the thickness of the lower electrode is formed by printing a paste-like material
Consisting of 0.5 to 20 μm electrodes.
Containing lead-based piezoelectric element, including lead-based upper electrode
The piezoelectric element is fired after printing the paste-like material
Characterized by having a perovskite structure
Inkjet head. Wherein the surface roughness of the lower electrode, according to claim 1-in, wherein a is less than the thickness of the lower electrode
Jet head. Wherein the lower electrode comprises a first lower electrode and the second
Characterized by a two-layer superposed structure of lower electrodes
The ink jet printer according to claim 1 or 2,
Good. 4. One or more nozzles, said nozzles communicating with each other
Pressure chamber and ink supply path for supplying ink to the pressure chamber
A flow path plate having the pressure chamber and the ink supply path on the flow path plate.
A vibration plate made of a bonded Si material , an upper electrode and a lower electrode
Pressure containing lead system mounted on the plate via the lower electrode
And a method of manufacturing an ink jet head having the same.
The lower electrode may be a paste-like material having a thickness of 0.5 to 20 μm.
Formed by printing, and then the lead system formed on it
Piezoelectric element, lead-containing piezoelectric element in the upper electrode
After printing the paste-like material, to obtain the piezoelectric effect
It is characterized by being formed by firing at a suitable temperature
Of manufacturing an inkjet head. 5. A method according to claim 1, wherein the lower electrode has a surface roughness
In according to claim 4 wherein the the thickness is less than this, wherein
Method for manufacturing a jet head. 6. The lower electrode has a first lower electrode.
Printing and firing the second lower electrode after printing and drying
Is formed by the superposition of two layers obtained by
The inkjet according to claim 4 or 5, wherein
Head manufacturing method.