JPH11179905A - Ink jet head and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of ink jet characteristics or fracture of a piezoelectric element part due to contact of an electrode film and ink caused by a void part existing on the surface of the piezoelectric element part or irregularities on the surface. SOLUTION: An impregnating material 18 is applied to the surface of a piezoelectric element 13 constituting the piezoelectric element part 14 of an ink head and the material 18 is hardened thus flattening the surface. An electrode film 16 and a protective film 17 are then formed on the flattened surface. Since uniform electrode film 16 and protective film 17 can be formed on the surface at the piezoelectric element part 14, the electrode film 16 is prevented from being exposed and fracture of the piezoelectric element part due to contact of ink and the electrode is prevented thus realizing a highly reliable ink jet head.

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 for printing on recording paper or the like by discharging ink, and more particularly to a structure of a piezoelectric element of an ink jet printer head and a method of manufacturing the same.

[0002]

2. Description of the Related Art As an ink jet head constituting an ink jet print, a piezoelectric element such as a piezo element (hereinafter, referred to as a PZT element) and an electrode film for applying a voltage for generating a pressure to the piezoelectric element are formed. An ink jet head that has a pressure generating section composed of an insulating film for maintaining insulation between ink and electrodes and an ink discharge nozzle, generates pressure by an applied voltage, and discharges ink from the nozzle is disclosed in 173339 and JP-A-4-163050.

For example, FIG. 2 is a sectional view showing an example of this type of ink jet head. PZT by supporting material 15 facing ink liquid chamber 11 having ink nozzle 12
An element 13 is disposed, and a piezoelectric element portion 14 configured by a part of the PZT element 13 projects into the ink liquid chamber 11. Then, by applying a voltage through an electrode film 16 provided on the piezoelectric element section 14, pressure is generated in the ink in the ink liquid chamber 11 in the piezoelectric element section 14, and the ink is ejected from the nozzle 12. Have been.

FIG. 3 is an enlarged sectional view of a piezoelectric element used in such an ink jet head. An electrode film 16 is formed on the surface of the piezoelectric element portion 14 of the PZT element 13 which is a piezoelectric element material, and a protective film 17 made of an insulating material is formed on the electrode film 16.

[0005]

However, in the structure of the piezoelectric element section shown in FIG.
Since irregularities such as irregularities due to grain boundary voids of a piezoelectric element material such as ZT and irregularities X generated during processing for forming an ink liquid chamber in the piezoelectric element part are present on the surface of the PZT element 13, the irregularities X The electrode film 16 and the protective film 17 are formed unevenly. In particular, in the deep recess, the electrode film 16 and the protective film 17 become incomplete films, and the surface of the electrode film 16 or the surface of the PZT element 13 is exposed in the ink liquid chamber at this portion. For this reason, contact between the ink and the electrode film 16 occurs, and when a voltage is applied to the piezoelectric element 13 through the electrode film 16, a short circuit or a short circuit may occur, and an ink ejection effect as designed may not be obtained. The above-mentioned voltage is applied, and the piezoelectric element is broken.

SUMMARY OF THE INVENTION An object of the present invention is to form a uniform electrode film and a protective film on the surface of a piezoelectric element portion, and to prevent a deterioration in ink discharge characteristics and a breakage of the piezoelectric element portion due to contact between the ink and the electrode film, and to provide a highly reliable piezoelectric element. An object of the present invention is to provide an ink jet head and a method of manufacturing the same.

[0007]

According to the present invention, there is provided an ink discharge nozzle formed in communication with an ink liquid chamber, a piezoelectric element for applying pressure to the ink to discharge the ink from the ink discharge nozzle, An electrode film formed on the surface of the piezoelectric element portion to apply a voltage for generating a pressure to the piezoelectric element portion, and a protective film made of an insulating material covering the electrode film, for printing on recording paper or the like. In the ink jet head for discharging ink to be performed, a surface of the piezoelectric element portion is flattened.
Here, the piezoelectric element section is configured such that voids and irregularities on the surface are filled with an impregnating material and cured. Further, the impregnating material is made of a liquid organic material having a high insulating property such as an epoxy resin, a polyester resin, or water glass, or a gel inorganic material.

According to the manufacturing method of the present invention, the electrode forming surface of the piezoelectric element formed of a piezoelectric material formed in a required shape is vacuum impregnated or impregnated with an impregnating material formed of a liquid organic material or a gel inorganic material having a high insulating property. A step of filling and curing by pressure impregnation, a step of forming an electrode film on a surface of a required area of the impregnated piezoelectric element portion, and a step of forming a protective film in a region including the electrode film. It is characterized by the following.

According to the ink jet head of the present invention,
The surface exposed voids and the surface generated in the piezoelectric element are sealed or flattened, and an electrode film and a protective film are formed thereon, so that a uniform electrode film and a uniform protective film can be formed. Contact between the ink and the electrode film is prevented, and a design characteristic is observed, and a highly reliable inkjet head can be configured.

[0010]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view for explaining an embodiment of the present invention, and is an enlarged cross-sectional view of a piezoelectric element portion of the ink jet head shown in FIG. That is, as shown in FIG. 2, the ink liquid chamber 1 having the ink nozzle 12 is provided.
The PZT element 13 is arranged by a support member 15 facing 1, and a piezoelectric element portion 14 formed by a part of the PZT element 13 projects into the ink liquid chamber 11.
The surface of the required area of the piezoelectric element section 14 is Au
And the like, and the electrode film 16 is formed.
Over the entire surface of the PZT element, a protective film 17 made of an insulating material such as epoxy, silicone, silicon oxide, or silicon nitride is formed.

Here, the surface of the piezoelectric element portion 14, that is, the surface before the electrode film 16 is formed, is made of PZT.
There are irregularities due to grain boundary voids peculiar to the material of the element and irregularities X when the ink liquid chamber is formed and processed. The impregnating material 18 made of a liquid organic material or a gel inorganic material having high properties is filled and cured by vacuum impregnation or vacuum pressure impregnation, whereby the concave portion is sealed with PZ.
The surface of the T element 13 is flattened. As the impregnating material 18 to be filled and cured, epoxy resin,
A material having high insulation properties such as polyester resin and water glass is desirable.

[0012] Then, the piezoelectric element portion 14 is flattened by filling and hardening the impregnating material 18 so that unevenness is eliminated.
The electrode film 16 is formed by forming an Au film on the surface by sputtering, and the protective film 17 is formed by further forming an insulating material on the electrode film 16 by sputtering or coating. For this reason, especially when the electrode film 16 is formed,
Since there is no concave portion on the surface of the piezoelectric element portion 14,
The electrode film 16 having excellent coverage is formed, and the coverage of the protective film 17 formed thereon is also improved. Thereby, the uniformity of the protective film 17 is improved, and the electrode film 16 is not exposed.

Therefore, by applying a required voltage through the electrode film 16, the piezoelectric element section 14 generates a pressure on the ink in the ink liquid chamber 11, and
2 to eject ink. At this time, the electrode film 16 is not exposed in the ink liquid chamber 11 due to the uniformity of the protective film 17, and the ink does not come into contact with the electrode film at all, so that the designed pressure is generated. At the same time, breakage of the piezoelectric element is prevented.

The present invention is not limited to the ink jet head having the above-described structure as long as the ink jet head has a piezoelectric element portion in which an electrode film formed on the surface may come into contact with ink. The same can be applied to the inkjet head having the configuration described above.

[0015]

As described above, according to the present invention, the sealing process and the flattening process are performed on the exposed voids and the surface irregularities generated on the surface of the piezoelectric element constituting the ink jet head. A uniform electrode film and protective film can be formed on the surface. Therefore, a highly reliable ink jet without breakage of the piezoelectric element due to contact between the ink and the electrode can be obtained. Further, since the sealing treatment is performed on the voids exposed on the surface of the piezoelectric element member, the piezoelectric element portion itself is reinforced, and an ink jet head having excellent durability can be obtained. As a result, the ink ejection operation is excellent, and the ink can always be ejected stably. This makes it possible to obtain a clear print image without unevenness in print quality over a long period of time.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a piezoelectric element according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of an inkjet head to which the present invention is applied.

FIG. 3 is an enlarged sectional view of a conventional piezoelectric element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Ink liquid chamber 12 Ink nozzle 13 PZT element 14 Piezoelectric element part 15 Support material 16 Electrode film 17 Protective film 18 Impregnation material X Void (unevenness)

Claims (4)

[Claims] An ink discharge nozzle formed in communication with an ink liquid chamber; a piezoelectric element for applying pressure to the ink to discharge the ink from the ink discharge nozzle;
An electrode film formed on the surface of the piezoelectric element portion to apply a voltage for generating a pressure to the piezoelectric element portion, and a protective film made of an insulating material covering the electrode film, for printing on recording paper or the like. In the ink jet head for discharging ink to be performed, the surface of the piezoelectric element portion is subjected to a flattening process. 2. The piezoelectric element portion according to claim 1, wherein voids and irregularities existing on the surface are filled with an impregnating material and cured.
2. The inkjet head according to item 1. 3. The ink jet head according to claim 2, wherein the impregnating material is made of a liquid organic material having high insulating properties such as an epoxy resin, a polyester resin, or water glass, or a gel inorganic material. 4. An electrode forming surface of a piezoelectric element portion made of a piezoelectric material formed in a required shape is filled with an impregnating material made of a highly insulating liquid organic material or a gel inorganic material by vacuum impregnation or vacuum pressure impregnation. And curing, a step of forming an electrode film on a surface of a required area of the impregnated piezoelectric element portion, and a step of forming a protective film in a region including the electrode film. A method for manufacturing an ink jet head.