JP2000085124A - Ink jet head and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance various strengths at the actuator part by providing a piezoelectric element in which the actuator part has trapezoidal cross-section in the direction orthogonal to a piezoelectric element film, i.e., the oscillating direction of the actuator part, enlarged to the pressure chamber electrode side. SOLUTION: A piezoelectric element 2 at the actuator part has trapezoidal cross-section in the direction orthogonal to the film face thereof, i.e., the oscillating direction of an actuator part, enlarged to the diaphragm/pressure chamber electrode 1 side. Consequently, the side face inclines against the film face of the diaphragm/pressure chamber electrode 1. Since the joint to the pressure chamber electrode 1 composed of a substance having high Young's modulus is not steep at the time of deformation incident to ink ejection, undue concentration of stress is prevented. Furthermore, stress generated at the side wall part due to some cause of production, or the like, can be dispersed. According to the structure, various strengths can be enhanced at the actuator part including the pressure chamber electrode 1 and the counter-pressure chamber electrode 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer, and more particularly, to a shape and a structure of a piezoelectric element of an actuator portion of a head and a manufacturing method therefor.

[0002]

2. Description of the Related Art With the development of OA in recent years, ink jet printers are widely used in offices and homes.

[0003] By the way, several types of ink jet heads used in ink jet printers have been proposed under recent demands for low noise, high print quality and the like, but they are generally divided into two types. be able to.

In the first method, a part of an ink flow path (ink chamber) is formed of a piezoelectric material or the like, and an electric pulse is applied to the piezoelectric material to deform the piezoelectric material, thereby forming a part of the ink flow path. And a pressure pulse is generated in the ink flow path, and an ink droplet is ejected from the nozzle by the pressure pulse.

In the second method, a heating resistor is formed in an ink flow path, and an electric pulse is applied to the heating resistor to generate heat, thereby causing the ink in the ink flow path to boil, thereby generating a vapor bubble. Then, an ink droplet is ejected from the nozzle by the vapor bubble.

The present invention relates to an ink jet printer of the first type in which a portion called an actuator forming a part of a pressure chamber is vibrated to generate pressure in the pressure chamber to discharge ink. For,
Hereinafter, this type of ink jet printer and related technologies (however, for convenience of the present invention, those described in the "conventional technology" section, not all of which are known)
Will be described in some detail with reference to the drawings.

FIG. 2 shows a basic cross section in the vibration direction of one element (an ink jet head composed of a set of actuators, ink chambers, nozzles, etc.) of a head of this type of ink jet printer and a direction perpendicular to the paper surface to be printed. It is shown.

In FIG. 1, reference numeral 1 denotes a C having a thickness of about 2 μm.
It is a diaphragm and pressure chamber side electrode made of an r plate (film). 2
Stands for lead zirconate titanate (hereinafter referred to as PZT)
This is a piezoelectric element composed of Reference numeral 3 denotes an anti-pressure chamber side electrode made of Pt having a thickness of about 0.1 μm. 4 is 200μ
A pressure chamber component made of photosensitive glass having a thickness of about m. Reference numeral 5 denotes an ink flow path component formed by bonding a number of SUS thin plates. Reference numeral 6 denotes a nozzle plate made of polyimide having a thickness of about 20 μm. 7 is a nozzle hole. 8
Is a pressure chamber (ink chamber) in which pressure for discharging ink from the nozzle is generated.

In the above configuration, when a predetermined pulse-like voltage is applied to the Cr diaphragm and the Pt electrode, the piezoelectric element made of PZT contracts in the plane direction, and as a result, the actuator section is pressurized by the bimetal effect. Deforms to protrude toward the room.

[0010] With the pressure generated by this, a predetermined amount of ink in the pressure chamber passes from the nozzle 9 provided on the nozzle plate to the outside (on paper) through the projecting ink flow path 9 in the ink flow path component. The ink protrudes, and the ink adheres to the paper in a dot shape.

FIG. 3 shows an example of the head of an actual ink jet printer viewed from the top. However, a number of elements of the ink jet head are arranged in a predetermined pattern (however, in FIG. 3, the elements are complicated). Therefore, only three of the elements of the ink-jet head on the strip arranged in parallel in a large number are shown.) According to a program linked with paper feed, these elements are moved in the main scanning direction and / or on the paper. In the sub-scanning direction, printing is performed by discharging ink at a predetermined position at a predetermined position.

Furthermore, for example, by installing an ink jet head for discharging ink of each color of black, cyan, magenta, and yellow, and discharging ink by a dedicated program, not only characters but also pictures and the like can be obtained. Color printing is also done.

Next, a description will be given of a method of manufacturing the conventional ink-jet head, focusing on the actuator section, with reference to FIG.

(A) A substrate made of ceramic such as SiO ₂ or photosensitive glass, a diaphragm, a pressure chamber component, etc.
The lower electrode made of PZT, the piezoelectric element film made of PZT, and the Pt thin film are formed in the same order (in the case of a substrate which also serves as a pressure chamber made of photosensitive glass or the like as shown in FIG. .

(B) Then, unnecessary portions of the Pt thin film and the piezoelectric element film made of PZT are removed by laser, other mechanical means such as ions or ultrasonic waves to separate them, and the upper portions corresponding to the respective nozzles and pressure chambers are removed. Electrodes and piezoelectric elements.

Further, necessary processing such as connection of each part is performed, and an ink jet head is manufactured.

[0017]

However, in recent years, particularly in recent years, it has been attempted to form a diaphragm, a piezoelectric element or the like as a thin film which can be finely processed (small and precise) with the aim of further miniaturization and higher performance. However, simply doing so by the conventional material, shape and structure of the actuator part and the manufacturing method therefor and the technology of extension thereof,
It decreases various strength just each part for miniaturization, not thus lowering the like product life can be avoided.

In addition, productivity at the time of device fabrication may be reduced.

For this reason, not only the miniaturization, the cost, and the controllability of the ink discharge amount and the like become high performance, but also the ink jet head which can cope with these, has excellent strength of each part, and is easy to manufacture. Further, there has been a demand for the development of an ink jet printer having a small size, low cost, a long product life, and excellent performance.

[0020]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made in consideration of the shape and structure of an actuator portion of an ink-jet head, particularly, a piezoelectric element portion, and furthermore, has such a shape and structure. Is an ingenuity in the manufacturing method.

Specifically, the configuration is as follows.

According to the first aspect of the present invention, in principle, the electrodes on the pressure chamber side provided corresponding to the patterns of the plurality of actuator portions and the piezoelectric element film (PZT for forming the piezoelectric element of the actuator portion) A piezoelectric element having a trapezoidal cross section extending in a direction orthogonal to the membrane (the direction of vibration of the actuator section, in the direction of ejecting ink in FIG. 2) on the electrode side on the pressure chamber side; And characterized in that:

With the above configuration, the following operation is performed.

Since the cross section of the piezoelectric element is trapezoidal, which expands toward the common electrode side, when the piezoelectric element is deformed due to the ejection of ink, the joint with the electrode on the pressure chamber side made of a substance having a high Young's modulus is not steep, and as a result, Various strengths are improved because excessive concentration of stress does not occur and stress generated in the side wall portion for some reason such as manufacturing is dispersed because the area is increased. Also,
At the same time, various strengths of the actuator section (including the electrode on the pressure chamber side and the electrode on the counter pressure chamber side) are improved.

According to the second aspect of the present invention, in the piezoelectric element, the inclination angle of the oblique side of the trapezoidal cross section with respect to the pressure chamber side electrode, or the peripheral (wall) surface is formed with respect to the pressure chamber side electrode. The present invention is characterized in that the piezoelectric element is an appropriate inclination angle cross-sectional type piezoelectric element having an inclination angle of 20 degrees or more and 60 degrees or less.

With the above configuration, the following operation is performed.

The piezoelectric element is an appropriate tilt angle cross-sectional type piezoelectric element in which the inclination angle of the trapezoidal oblique side of the cross section with respect to the pressure chamber side common electrode is not less than 20 degrees and not more than 60 degrees. Not only is the service life improved, but also the amount of ink projected toward the ink chamber due to a predetermined electric pulse, the amount of distortion and the responsiveness, and hence the amount of ink discharged are appropriate.

According to the third aspect of the present invention, a protective film made of a material having a Young's modulus lower than that of the piezoelectric element, such as polyimide, is provided on the outer peripheral portion of the piezoelectric element opposite to the electrode on the pressure chamber side. It is characterized by doing.

With the above configuration, the following operation is performed.

The protective film not only protects the piezoelectric element from a mechanical external force or a foreign substance applied for some reason such as an error at the time of manufacturing, but also, depending on the manufacturing method, the upper surface (the anti-earth side) of the piezoelectric element which is individualized at the time of manufacturing. For example, when forming or attaching a thin metal film for the (anti) pressure chamber side electrode, the film material hangs down from the top surfaces of the individualized piezoelectric elements, or such a state occurs. To prevent For this reason, when forming the metal film for the pressure chamber side electrode, the thin Cr film is flattened (flat) without sagging from the upper surface of the individualized piezoelectric element, and a secondary stress is generated during vibration. Also does not occur.

Since the Young's modulus of the piezoelectric element is smaller than that of the piezoelectric element, the piezoelectric element does not not only exert an excessive force upon deformation for ink discharge, but also has a mechanical connection between the pressure chamber side electrode and the side surface of the piezoelectric element. By continuously transmitting the force, the lower peripheral portion of the piezoelectric element is less likely to receive excessive stress from the pressure chamber side electrode having high strength such as Cr.

In the invention according to claim 4, the protective film has a Young's modulus of 1/20 or less 1/50 or more of the piezoelectric element, preferably 1/25 or less 1/40 or more, more preferably about 1/33. Characterized in that it is a suitable Young's modulus protective film made of the following materials.

With the above configuration, the following operation is performed.

Since it is an appropriate Young's modulus protective film, it is easy to select a material (for example, a resist or polyimide may be used), and the stress concentration applied to the pressure chamber side (lower part) around the piezoelectric element during deformation is further relaxed. .

According to the fifth aspect of the present invention, the cross section of the electrode on the pressure chamber side and the direction perpendicular to the piezoelectric element film has a trapezoidal shape in which the electrode side on the pressure chamber side is narrowed within a range of 120 to 160 degrees. A piezoelectric element, an electrode on the side opposite to the pressure chamber, and a protective film made of a substance having a Young's modulus lower than that of the piezoelectric element existing on the outer side of the piezoelectric element on the side opposite to the pressure chamber of the electrode on the side of the pressure chamber. It is characterized by having.

With the above configuration, the following operation is performed.

As with the third aspect, the protective film exhibits various technical effects. For this reason, various strengths of the piezoelectric element and the actuator part are improved even though the joint between the side surface of the piezoelectric element and the electrode on the pressure chamber side is steep (at an angle of 90 degrees or more).

In the invention according to claim 6, the protective film has a Young's modulus of 1/20 or less / 1/50 or more of the piezoelectric element, preferably 1/25 or less / 1/40 or more, more preferably about 1/33 or less. Characterized in that it is a suitable Young's modulus protective film made of the following materials.

With the above configuration, the following operation is performed.

The same operation as that of the fourth aspect of the invention is performed, and the effect is obtained.

According to the seventh aspect of the present invention, an electrode on the pressure chamber side, a piezoelectric element having a trapezoidal cross section in a direction perpendicular to the piezoelectric element film extending toward the pressure chamber side, an electrode on the opposite pressure chamber side, or an electrode on the opposite side. In addition to the above, a method for manufacturing an ink jet head having a protective film made of a substance having a Young's modulus lower than the piezoelectric element around the piezoelectric element opposite to the pressure chamber side of the electrode on the pressure chamber side, In order to form a trapezoid in which the cross section in the direction perpendicular to the film surface is inclined toward the pressure chamber side by tilting the side surface of the piezoelectric element, from the counter pressure chamber side with a strong acid such as a solution containing hydrofluoric acid and nitric acid, The method is characterized by having a strong acid use base forming step of melting and processing the inclined side surface by etching.

With the above configuration, the following operation is performed.
An electrode on the pressure chamber side, a piezoelectric element having a trapezoidal cross section in a direction perpendicular to the piezoelectric element film extending toward the pressure chamber side, and an electrode on the counter pressure chamber side or, in addition thereto, a counter pressure on the electrode on the pressure chamber side. In a step of forming a strong acid using base in a method of manufacturing an ink jet head having a protective layer made of a substance having a lower Young's modulus than the piezoelectric element on the chamber side and around the piezoelectric element, the side surface of the piezoelectric element is inclined. In order to make the cross section in the direction perpendicular to the piezoelectric element film into a trapezoid that spreads to the pressure chamber side (with the piezoelectric element attached to the pressure chamber parts, etc.), a resist having certain properties such as acid resistance is used. The attached piezoelectric element is melted with a strong acid such as a solution containing hydrofluoric acid and nitric acid by etching from between the resists, and the side surface thereof is inclined so as to be narrower toward the mask side.

Thereafter, an ink jet head is manufactured by taking steps such as formation of a protective film.

According to the present invention, the electrode on the pressure chamber side and its cross section in a direction perpendicular to the surface of the piezoelectric element film have a trapezoidal shape narrowed in the range of 120 to 160 degrees toward the pressure chamber. Inkjet having a piezoelectric element, an electrode on the side opposite to the pressure chamber, and a protective film made of a substance having a Young's modulus lower than that of the piezoelectric element on the side of the electrode opposite to the pressure chamber and on the outer periphery of the piezoelectric element. A method of manufacturing a head, in which a side surface of the piezoelectric element is inclined to form a trapezoidal cross section,
A strong acid use platform forming type step of performing a process of forming a side surface inclined by a strong acid such as a solution containing hydrofluoric acid and nitric acid by etching (in a state where the piezoelectric element is not fixed to the electrode on the pressure chamber side); A trapezoidal inversion step of attaching the trapezoidal piezoelectric element formed in the strong acid trapezoid forming step to the electrode on the pressure chamber side by transferring or joining the narrowed surface thereof.

With the above configuration, the following operation is performed.

In the step of forming a platform using a strong acid, the step (7)
The same processing as that of the invention is performed.

In the trapezoid reversal step, the trapezoidal piezoelectric element molded in the strong acid trap forming step is attached to the electrode on the pressure chamber side by transferring or joining the narrowed surface.

Thus, the piezoelectric element is joined to the electrode on the pressure chamber side in such a manner that the side surface is inclined so that the common electrode side becomes narrower.

It should be noted that a protective film forming step is also performed between or after these two steps.

According to the ninth aspect of the present invention, the Young's modulus of the material of the protective film is 1/20 that of the piezoelectric element.
The method is characterized in that it has a protective film substance selection step of selecting a substance of 1/50 or more, preferably 1/25 or less, 1/40 or more, more preferably about 1/33.

With the above configuration, the following operation is performed.

In the step of selecting a material for the protective film, the Young's modulus of the material for the protective film is set to be の of that of the piezoelectric element.
A substance having a value of 0 or less and 1/50 or more is selected, and this material is applied around the piezoelectric element whose side surface is inclined, thereby forming a protective film.

[0053]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on its embodiments.

(First Embodiment) FIG. 1 conceptually shows the structure of an actuator section of an ink jet head according to a first embodiment of the present invention.

It should be noted that the actuator portion of the ink jet head of the present embodiment, in particular, each portion except for the piezoelectric element is basically the same as the respective portions of the ink jet head shown in FIG. For this reason, also in FIG. 1, those parts are denoted by the same reference numerals as those in FIG. 2, and the description thereof is omitted.

The joining of the glass plate forming the pressure chamber with the diaphragm and lower electrode is not directly related to the gist of the present invention, and there are a number of known techniques. .

The following description focuses on matters that are closely related to the present invention. These are the same in the other embodiments.

Reference numeral 1 in the figure denotes a diaphragm / pressure chamber side (lower) electrode. 102 is a piezoelectric element. Reference numeral 3 denotes an individual electrode on the opposite side (upper side) of the pressure chamber.

As shown in this figure, the cross section of the piezoelectric element of the actuator section of this embodiment in the direction perpendicular to the film surface and in the direction in which the actuator vibrates expands toward the diaphragm / pressure chamber side electrode. It is trapezoidal. For this reason, the surface of the side (wall) is configured to be inclined with respect to the film surface of the diaphragm / pressure chamber side electrode.

Hereinafter, a method of manufacturing the ink-jet head of this embodiment, focusing on the actuator section, will be described with reference to FIG. 5 showing a schematic manufacturing procedure.

(A) On the pressure chamber parts, lower (on the pressure chamber side)
From the top to the uppermost Pt film of the inkjet component in which the Cr film 44, the PZT film 43, and the Pt film 42 are formed in order.
To individualize the upper electrode according to the pattern of the pressure chamber,
A mask 51 slightly smaller than the pressure chamber is applied to the resist. The production of the pressure chamber components in this state is a so-called well-known technique, and therefore, the description thereof is omitted. Further, in practice, for example, a very thin base (media) film is formed between the Cr film and the PZT film in order to improve the bondability between the two films.
These are not directly related to the spirit of the present invention. For this reason,
Illustration and explanation of these are also omitted.

(B) In the state of (a), the upper electrode 3 corresponding to the pressure chamber is formed (individualized) by RIE (reactive ion etching). After that, the above-mentioned resist is removed.

(C) In order to remove unnecessary portions of PZT by etching, the upper and side surfaces of the upper electrode and the PZT are removed.
An acid-resistant resist 52 is applied to a portion of the upper surface of the T film that slightly protrudes from the outer periphery of the upper electrode.

(D) The PZT 53 where the resist is not applied is removed by etching using a strong acid.

(E) In correspondence with the pressure chamber, a piezoelectric element is formed in which the upper electrode and the side face are inclined toward the pressure chamber.

Next, the contents of the inclination of the side wall surface of the piezoelectric element in (d) and (e) will be described with reference to FIG.

In FIG. 6, reference numeral 44 denotes a Cr film serving as a pressure side electrode. Reference numeral 43 denotes a PZT film serving as a piezoelectric element. Reference numeral 3 denotes an upper electrode already individualized in the step (d). 52 is a resist.

Then, the surface of the PZT film between the resists is exposed to a solution containing hydrofluoric acid and nitric acid to remove unnecessary PZT film.
Is melted and removed.

At this time, as shown by the three isochronous erosion lines in this figure, the portion to be melted and removed is related to the time of exposure to the liquid or to the course of the reaction. Wider and narrower at the bottom.

For this reason, the side surface of the piezoelectric element necessarily has a shape expanding downward, and is inclined. (Note that, in reality, the cross section of the piezoelectric element is not a perfect trapezoid, and may often have a somewhat complicated shape as shown in, for example, FIGS. 7A and 7B. In the case of, the inclination angle is the narrow part 2 near the upper and lower horizontal planes.
It refers to the corner of the main part 23 at the center of the inclined side surface excluding 1, 22. That is, deviations and irregularities from some uniformity are ignored. Next, the strength in this case will be described.

Table 1 shows the results of a high-speed vibration (1 million Hz) test on the relationship between the angle formed by the side substrate and the life. Here, the life was defined as the number of vibrations at which a voltage of 50 V was applied to the PZT thin film having a thickness of 3 μm and the vibration displacement became 80% of the initial value.

[Table 1]

From Table 1, it can be seen that the life is increased by making the inclination angle smaller than 90 degrees, and the life is greatly increased especially from 60 degrees or more. (Note that, although this is strictly different from the actual use condition, it is needless to say that there is not much difference from the actual use based on experience and common technical knowledge.) For this reason, FIG. As shown in (1), when the connection between the Cr diaphragm and the piezoelectric element is steep (around 90 degrees),
The lower portion 24 of the outer peripheral portion of the piezoelectric element receives a large tensile force from the Cr diaphragm at the time of vibration, while the upper surface portion 25 contracts, and therefore receives a large stress. (At this time, since the upper electrode is made of Pt or Ag, which is much thinner than the piezoelectric element and whose Young's modulus is smaller than Cr, this effect can be neglected in practice.) As shown in the figure, if the side surface is inclined, the lower part of the outer peripheral part receives a force due to the contraction of the upper part, and the distance L may be large, and the distance L is relatively small. As a result, the force applied to the entire piezoelectric element is moderate. It is considered that the stress concentration is reduced because the change in the geometrical shape is also reduced.

In addition, a large residual stress may be present on the side surface of the piezoelectric element or a stress may be generated due to transfer from the substrate during the manufacturing process, sputtering, or other interaction between the films. If the area is large due to the inclination, it is considered that the stress is relieved.

On the other hand, the initial value of the amplitude of the vibration when the inclination angle is given becomes smaller as the inclination angle becomes smaller than 90 degrees.

That is, in the experiment, as compared with the amplitude at the inclination angle of 90 degrees, the decrease in the amplitude is less than 20 degrees until the angle is 20 degrees.
%, But when the angle became 10 degrees, the amplitude decreased to about 55%.

For this reason, as shown in FIG.
The vibration of the diaphragm is hindered by the fact that the piezoelectric element is thinner than the diaphragm made of r and there is no electrode on the upper side, and the lower part of the inclined portion on the side which seems not to contribute (smallly) to the bimetal effect is wide. Seems to be from.

Further, since the Cr diaphragm on the side wall of the pressure chamber is constrained by the side wall, it is unlikely or hardly deformed, and the presence of the piezoelectric element in this part does not have much significance.

As a result, it has been found that it is effective to incline the side surface in the range of 20 to 60 degrees in order to obtain a large amplitude and increase the life.

(Second Embodiment) Hereinafter, the present invention will be described based on a second embodiment.

This embodiment is basically the same as the first embodiment. However, on the side wall surface of the piezoelectric element, there is a protective substance film having a lower Young's modulus than the piezoelectric thin film, that is, a film 11 of a polyimide resin, for example, a polyimide resin film around the piezoelectric thin film processed as shown in FIG. Are different.

The space between the piezoelectric elements formed individually by the trapezoidal cross section of the actuator section is filled with a polyimide resin by spin coating in the state shown in FIG. 5 (e). Manufactured.

Thus, the piezoelectric element is mechanically and physically protected in the event of contact with foreign matter due to some cause during manufacturing or the like.

It has also been found that the strength of the actuator can be increased to extend the product life. Table 2 shows the test results. The test conditions are the same as in the first embodiment.

[Table 2]

For the reason, when the actuator section is distorted as shown in FIG. 11, the contraction and stress f are transmitted to the outer peripheral portion of the Cr diaphragm through the upper and middle portions of the PZT side wall portion. It is considered that the relaxation of the large stress generated at the lower portion of the side wall portion and the like contributes.

Further, a sudden stress is applied from the Cr diaphragm or a sudden stress is generated inside due to the vibration. By making the Cr diaphragm and other piezoelectric elements continuous, these forces are generated. It seems to alleviate this.

Further, during these operations, the contact area is increased correspondingly because the side wall of the piezoelectric element is inclined, and this is considered to be effective for reasonably contracting and transmitting stress.

In this embodiment, as shown in the figure, the polyimide resin is applied to the upper surface near the outer peripheral portion of the piezoelectric element. However, it is preferable from the viewpoint of preventing contact of foreign substances and increasing the contact area. Of course.

This polyimide resin has a Young's modulus of about 3 × 10 ¹¹ N / m ^{2 of} PZT.
Since it is 10 ⁹ N / m ² and 1/33, the vibration of the actuator is of course not adversely affected.

Furthermore, even if it is not exactly 1/33 or its vicinity (± 5%), it is roughly 2/3 to 3 /
If it is within the range of 2 (1/20 or less and 1/50 or more), more surely within the range of 3/4 to 4/3 (1/25 or less 1/40 or more), the vibration of the actuator is adversely affected. It seems to have no effect and can provide a protective effect.

(Third Embodiment) Hereinafter, the present invention will be described with reference to the third embodiment.
A description will be given based on examples.

In this embodiment, the piezoelectric element having a trapezoidal cross section is inverted upside down, ie, the long side is up and the short side is down (pressure chamber side), as in the first and second embodiments. Different.

As shown in FIG. 12, the piezoelectric element 1021 is
The inclination angle of the side wall surface is 90 degrees or more, that is, the surface on the pressure chamber side is smaller (narrower) than the surface on the opposite pressure chamber side. Also in this case, when the space between the piezoelectric elements on the lower electrode film was filled with the polyimide resin, the same effects as those of the second embodiment were obtained in terms of improvement in strength, product life, and the like.

In particular, the angle between the side wall surfaces is 120 degrees to 1 degree.
By filling the periphery with a polyimide resin within the range of 60 degrees, damage to the piezoelectric element was prevented, and good vibration characteristics and good life could be obtained.

Table 3 shows the test results. The test conditions are the same as in the first and second embodiments.

[Table 3]

For the reason, as in the second embodiment, the polyimide resin causes a large shrinkage of the upper and middle portions of the piezoelectric element by Cr.
Probably because of the smooth transmission to the diaphragm.

In the current process, it is not easy to make the inclination of the side surface more than 90 degrees.
It was manufactured by transferring and joining microfabricated material to the pressure chamber side with an angle of up to degrees.

Hereinafter, this schematic manufacturing method will be described with reference to FIG.
This will be described with reference to FIG.

(A) First, a Pt thin film 42 is formed on the entire surface of the MgO substrate 41 by sputtering or the like (opposite the pressure chamber).
Attached for electrode formation.

(B) The upper electrode 3 is formed by individualizing the Pt thin film on the MgO substrate according to the pressure chamber pattern by etching or the like.

(C) A PZT film layer 43 is deposited on the entire surface of the MgO substrate and the upper electrode thereon by sputtering or the like.

(D) P formed on MgO substrate 41
By applying and etching a resist 52 along the pressure chamber pattern on the ZT film 43, the piezoelectric element 102 is individualized and its side surface is inclined.

(E) The polyimide resin 11 is filled by spin coating between the individualized space between the piezoelectric elements having inclined side surfaces and between the upper individual electrodes.

(F) In this state, on the photosensitive glass 4 on which the Cr film 44 is formed, the piezoelectric element and the polyimide resin are fixed to the Cr film together with the MgO substrate. Thereafter, the MgO substrate is removed by melting with hot phosphoric acid.

(Accordingly, in this case, the polyimide resin is flush with the upper electrode.) Then, after exposure with an ultraviolet exposure device, the polyimide resin is melted and removed with a 3% HF solution to remove the pressure chamber of the photosensitive glass. No processing such as removing the part corresponding to
Finally, the printer head was completed.

Although the present invention has been described based on the embodiments and examples, it is needless to say that the present invention is not limited to these.

That is, for example, the following may be performed.

1) Each part is made of a material different from that of the embodiments and the like, for example, the diaphragm and the lower electrode are made of Ti.

Alternatively, each part has a structure different from that of the embodiment or the like, for example, a lower electrode is formed on a ceramic diaphragm.

2) The diaphragm and lower electrode are individually provided for each pressure chamber so that distortion and stress due to vibration become independent.

3) The upper individual electrode is not smaller than the piezoelectric element but has the same area.

Further, the side portions are inclined or the corners of the thin film surface are rounded.

4) Similarly, it is manufactured (formed) by using another manufacturing method or solution.

5) The dimensions and the like are made larger or smaller depending on the use of the printer employing the ink jet head.

Similarly, the film thickness of each part is appropriately different from that of the embodiment according to the material and the like.

6) In the third embodiment, after the treatment (e), the surface smoothed by the polyimide resin and PZT
An r film is formed by sputtering or bonding. That is,
Other manufacturing methods.

[0116]

As described above, according to the present description, it is possible to provide a piezoelectric element having excellent strength and life (fatigue resistance) simply by the shape of the piezoelectric element and the presence of the polyimide resin film, and furthermore, an ink jet head. Not only is it possible to provide a piezoelectric / electrostrictive element, an ink jet head, and a printer that are not only small but easy to drive and control the amount of ink ejected, and consume low power and low noise.

Also, naturally, a piezoelectric element which is inexpensive,
An ink jet head and, consequently, a printer can be provided.

[Brief description of the drawings]

FIG. 1 is a view conceptually showing a trapezoidal cross section of a piezoelectric element according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram centering on a pressure chamber and a piezoelectric element portion of an ink jet head according to the related art.

FIG. 3 is a diagram illustrating an example of a state in which a large number of elements are patterned and arranged in an inkjet head.

FIG. 4 is a diagram illustrating a method of manufacturing an ink jet head according to the related art.

FIG. 5 is a first view of the ink jet head according to the present invention.
It is a figure showing the manufacturing method of an example.

FIG. 6 shows a first example of the inkjet head according to the present invention.
FIG. 6 is a diagram illustrating the principle of a process for making a peripheral side wall surface of a piezoelectric element inclined in a manufacturing method according to an embodiment.

FIG. 7 is a diagram showing the contents of the inclination angle of the peripheral side wall of the piezoelectric element.

FIG. 8 is a diagram for explaining the reason that the presence of the inclination angle of the peripheral side wall improves the strength of the piezoelectric element and the actuator.

FIG. 9 is a diagram for explaining the reason that the presence of the inclination angle of the peripheral side wall affects the vibration characteristics of the actuator.

FIG. 10 is a diagram conceptually showing a state in which the periphery is surrounded by a protective film in a second embodiment of the piezoelectric element according to the present invention.

FIG. 11 is a diagram conceptually showing a state in which the protective film transmits distortion and stress between the piezoelectric element and the Cr diaphragm in the above embodiment.

FIG. 12 is a view conceptually showing a piezoelectric element having an inverted trapezoidal cross section and a protective film around the piezoelectric element in a third embodiment of the piezoelectric element according to the present invention.

FIG. 13 is a diagram illustrating a schematic method for manufacturing the ink jet head of the embodiment.

[Description of sign]

 DESCRIPTION OF SYMBOLS 1 Vibration plate and pressure chamber side electrode 2 Piezoelectric element 3 Individualized anti-pressure chamber side electrode 4 Pressure chamber part 5 Ink flow path part 6 Nozzle plate 7 Nozzle hole 8 Pressure chamber (ink chamber) 9 Ink flow path 11 Polyimide resin Film 31 Substrate 32 Inkjet head element 41 MgO substrate 42 Pt film 43 PZT film 44 Cr film 51 Mask 52 Resist 53 Removed portion of PZT film 102 Piezoelectric element according to the present invention 1021 Piezoelectric element according to the present invention

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Osamu Watanabe 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd.

Claims (9)

[Claims] An electrode on the pressure chamber side, a piezoelectric element having a trapezoidal cross section in a direction perpendicular to the membrane surface extending toward the electrode on the pressure chamber side, and an electrode on the opposite pressure chamber side. An ink jet head, characterized in that: 2. The piezoelectric element has a trapezoidal cross section having an oblique side with an inclination angle of 20 with respect to the pressure chamber side electrode.
2. The ink jet head according to claim 1, wherein the piezoelectric element is a piezoelectric element having an appropriate inclination angle cross section of not less than 60 degrees and not more than 60 degrees. 3. A protection film made of a substance having a Young's modulus lower than that of the piezoelectric element is provided on the pressure chamber side opposite to the pressure chamber side and on the outer periphery of the piezoelectric element. The inkjet head according to claim 1 or 2. 4. The ink-jet head according to claim 3, wherein said protective film is an appropriate Young's modulus protective film made of a substance whose Young's modulus is 1/20 or less and 1/50 or more of the piezoelectric element. 5. An electrode on the pressure chamber side, a trapezoidal piezoelectric element whose cross section in a direction perpendicular to the membrane surface narrows in the range of 120 to 160 degrees on the electrode side on the pressure chamber side, An electrode on the pressure chamber side, and a protective film made of a material having a Young's modulus lower than that of the piezoelectric element, which is present on the outer peripheral portion of the piezoelectric element opposite to the pressure chamber side of the electrode on the pressure chamber side. Characteristic inkjet head. 6. The ink-jet head according to claim 5, wherein said protective film is an appropriate Young's modulus protective film made of a substance whose Young's modulus is not more than 1/20 and not more than 1/50 of the piezoelectric element. 7. An electrode on the pressure chamber side, a piezoelectric element having a trapezoidal cross section in a direction perpendicular to the membrane surface extending toward the pressure chamber side, an electrode on the counter pressure chamber side, or in addition to the electrodes on the counter pressure chamber side, A method of manufacturing an ink jet head having a protective film made of a substance having a Young's modulus lower than that of the piezoelectric element on the side opposite to the pressure chamber of the side electrode and around the piezoelectric element, wherein a side surface of the piezoelectric element is inclined. In order to make the cross section in the direction orthogonal to the film surface into a trapezoid that spreads to the pressure chamber side, it is inclined by etching from the direction opposite to the pressure chamber side with a strong acid such as a solution containing hydrofluoric acid and nitric acid. A method for manufacturing an ink jet head, comprising a step of forming a platform using a strong acid for forming a side surface. 8. A common electrode on the pressure chamber side, a piezoelectric element having a trapezoidal shape whose cross section in a direction perpendicular to the membrane surface narrows in the range of 120 ° to 160 ° on the pressure chamber side, An electrode and a method for manufacturing an ink jet head having a protective film made of a substance having a Young's modulus lower than that of the piezoelectric element on the side opposite to the pressure chamber of the electrode on the pressure chamber side and on the outer periphery of the piezoelectric element, Etching with a strong acid such as a solution containing hydrofluoric acid and nitric acid in order to make the side surface of the piezoelectric element inclined and make the cross section in the direction perpendicular to the film surface trapezoidal,
A step of forming a platform using a strong acid to form an inclined side surface,
A trapezoidal inversion step of attaching the piezoelectric element having a trapezoidal cross section formed in the strong acid use base forming mold step to a surface corresponding to the narrowed side of the piezoelectric element by transfer or bonding to the electrode on the pressure chamber side. A method for manufacturing an ink jet head. 9. A protective film material selecting step for selecting a material having a Young's modulus of 1/20 or less and 1/50 or more of the piezoelectric element as a material of the protective film. 9. The method for manufacturing an ink jet head according to claim 7.