JP3385935B2 - Ink jet recording head and method of manufacturing the same - Google Patents

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 used in an ink jet recording apparatus such as an ink jet printer for obtaining a visible image by selectively flying and fixing ink droplets on a recording paper according to input print data. Recording head.

More specifically, the present invention relates to an on-demand ink jet recording head in which a nozzle plate and an ink pressurizing chamber substrate are laminated and a piezoelectric film formed on the surface of the ink pressurizing chamber substrate is pressurized to cause ink droplets to fly to cause ink droplets to fly. .

[0003]

2. Description of the Related Art As a prior art relating to the present invention, there is Japanese Patent Publication No. 5-504740.

In this conventional example, a piezoelectric film is integrally formed on a substrate containing an ink pressurizing chamber by a so-called thin film manufacturing method such as sputtering or a sol-gel method, so that an on-demand type ink jet recording having a simple structure and high definition is formed. The head is realized. In particular, a highly accurate ink pressurizing chamber can be formed by using a silicon single crystal substrate as a base material and performing anisotropic etching.

FIG. 7 shows a cross-sectional view in the arrangement direction of an ink jet type recording head actuator using a conventional thin film PZT and a silicon single crystal substrate. Reference numeral 20 is a silicon single crystal substrate, 2 is a pressure chamber formed by anisotropic etching on the silicon single crystal substrate, 18 is a partition wall separating the pressure chambers, 21 is a silicon dioxide film, 10 is a lower drive electrode, Reference numeral 11 is a piezoelectric thin film, 12 is an upper drive electrode, and each thin film has a thickness of several 100 nm to several μm. Reference numeral 30 denotes a piezoelectric strain generating portion, and reference numeral 31 denotes a support portion which is interposed between the piezoelectric strain generating portion and the partition wall to support the piezoelectric strain generating portion.

When a voltage is applied between the lower drive electrode 10 and the upper drive electrode 12, the piezoelectric film 11 tends to contract in the film surface direction, but the silicon dioxide film 21 which is an elastic film on the lower surface of the piezoelectric film 11 contracts. The contraction is hindered and the contraction force becomes a deflection to the lower surface.

[0007]

Focusing on the deformation efficiency of such a unimorph type actuator and the structure of the elastic film and the supporting portion, the elastic film preferably has a high Young's modulus in the film surface direction, and the supporting portion is In order not to disturb the bending stress of the piezoelectric strained portion, it is better that it is easily stretched and has a low bending rigidity. However, in the conventional thin film type actuator, since the respective thin films are integrally formed, the elastic film and the film forming the supporting portion must use the same material.

The present invention is intended to solve such a problem. An object of the present invention is to propose a means for reducing manufacturing defects and improving reliability while increasing actuator displacement efficiency, and to achieve high density. It is to provide a high-performance inkjet recording head.

[0009]

An ink jet recording head according to the present invention comprises an ink pressurizing chamber arranged in a row on a silicon single crystal substrate through a partition, and one side of the pressurizing chamber is covered to cover the partition. A pressure generating film which is suspended and fixed by the pressure generating film and which is arranged so as to form one wall surface of the pressure chamber, and an ink discharge nozzle which communicates with each of the pressure chambers. An ink jet recording head that ejects ink by generated pressure, wherein the pressure generating film includes a piezoelectric film, lower and upper drive electrodes with the piezoelectric film interposed therebetween, and lower and upper drive electrodes. A piezoelectric strain generating section having an elastic film laminated on either side,
And a support portion that supports the piezoelectric strain generating portion on the partition wall, the support portion is made of a polymer resin film, and the elastic film is made of a material different from that of the support portion.

Further, in the method of manufacturing the ink jet recording head of the present invention, the piezoelectric film and the lower and upper drive electrodes and the lower and upper drive electrodes having the piezoelectric film interposed therebetween are formed on one surface of the silicon single crystal substrate. A step of forming a film forming a piezoelectric strain generating portion having an elastic film laminated on either side, a step of forming the piezoelectric strain generating portion by photoetching after that, and a partition wall of the piezoelectric strain generating portion thereafter. And a step of forming a film forming a supporting portion for supporting on the silicon single crystal substrate, and then forming a pressure chamber on the silicon single crystal substrate by etching the silicon single crystal substrate in rows through the partition walls. It is characterized by comprising a step of forming.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on an embodiment.

The structure of the ink jet recording head of the present invention will be described with reference to FIGS.

FIG. 1 is a schematic perspective view of an ink jet recording head according to an embodiment of the present invention.

Reference numeral 1 denotes an ink pressurizing chamber substrate, pressurizing chambers 2 arranged in a zigzag pattern in two rows, and ink (not shown) in each pressurizing chamber.
Has a common flow path 3 for supplying the pressure chamber 2 and a supply path 9 that connects the respective pressurizing chambers 2 with the common flow path 3. Array pitch is 180
1 inch, about 141 microns, 64 per row
By arranging the elements, it has realized a type recording head having a printing density of 360 dots / inch and 128 nozzles in two rows. 8
Is a wiring board for supplying a signal to the displacement element.

Reference numeral 6 denotes a nozzle plate having a plurality of ink ejection nozzles 7 corresponding to the pressurizing chamber 2. After the pressure chamber substrate 1 and the nozzle plate 6 are adhered, they are fitted on the base body 90 to form an ink jet recording head.

FIG. 2 is a cross-sectional view taken along the dashed-dotted line AA 'of FIG. 1 in the direction in which the pressure chambers are arranged. Silicon dioxide is formed on the lower surface of the pressure chamber substrate 1 to form a substantially rectangular pressure generating film 5. The film 21, the lower drive electrode 10, the piezoelectric film 11, and the upper drive electrode 12 are sequentially stacked to form the piezoelectric strain generating section 30. In this example, the lower drive electrode 10 is made thick and has the function of an elastic film together with the silicon dioxide film 21.

In this example, the pressure chamber pitch was 141 μm, the pressure chamber width was 50 μm, the length (in the depth direction in the figure) was 1.2 mm, and the partition wall width was 91 μm.

Reference numeral 32 denotes a resin film, which is adhered to the upper surface of the partition wall 18 and at least the end portion of the piezoelectric strain generating portion 30, and the strain generating portion 30
The pressure generating film 5 including the supporting portion 31 and the strain generating portion 30 is integrally formed with the pressurizing chamber substrate 1.

If the resin film 32 forming the support portion 31 is continuously covered up to the end face of the piezoelectric film 11 and the upper surface of the piezoelectric strained portion 30 as shown in FIG. You can also

Further, by covering only the end face of the piezoelectric film 11 as shown in FIG. 6, the end discharge between the upper and lower drive electrodes can be suppressed, and the upper surface of the piezoelectric strained portion 30 is restrained by the resin film to reduce the displacement. I won't let you.

A method of manufacturing the ink jet recording head of the present invention will be described with reference to FIGS. 3, 4 and 5. FIG. 3 shows a cross section taken along the line AA ′ of FIG. FIG. 4 shows a cross section taken along the line AA ′ of FIG. 1, like FIG. FIG. 5 is a sectional view in the flow path direction corresponding to each step of FIG.

In this example, the diameter is 100 mm and the thickness is 220 μm.
As shown in FIG. 3I, an etching protection layer 2 made of silicon dioxide is formed on the entire surface of the silicon single crystal substrate 20 which is a pressure chamber substrate having a (110) surface by a thermal oxidation method.
1 is formed to a thickness of 1 μm, and platinum for the lower drive electrode 10 is formed on the upper surface by a thin film forming method such as a sputtering film forming method.
A film is formed with a thickness of 00 nm. At this time, ultrathin titanium, chromium or the like may be interposed as an intermediate layer in order to increase the adhesion between the platinum layer and the upper and lower layers thereof. Further, if the lower drive electrode has heat resistance to the subsequent heating temperature, a conductive material such as iridium, rubidium, or an oxide thereof may be used for the lower drive electrode. The lower drive electrode 10 also serves as an elastic film together with the silicon dioxide film 21.

A piezoelectric film precursor 24 is laminated thereon. In this example, lead titanate and lead zirconate PZT-based piezoelectric film precursors having a molar composition ratio of 55% and 45% were prepared by the sol-gel method 8 times until the final thickness was 0.9 μm. Coating, drying, and degreasing were repeated to form a film. As a result of various trial experiments, the chemical formula of this piezoelectric film is Pb _C Ti _A Zr
_B O ₃ [A + B = 1], and A and C in the above chemical formula
However, if it is selected within the range of 0.5 ≦ A ≦ 0.6 and 0.85 ≦ C ≦ 1.10, it is possible to obtain the piezoelectricity that can be practically used. The film formation method is not limited to this method, and high frequency sputter film formation or
You may use CVD etc.

Next, as shown in FIG. 3 (II), the entire substrate is heated to crystallize the piezoelectric film precursor. In this example, the infrared radiant light source 29 is used to remove 70
The piezoelectric film was crystallized by heating for 5 minutes at 0 ° C. and allowing the temperature to fall naturally. By this step, the piezoelectric film precursor 2
No. 4 was crystallized and sintered with the composition as intended to form the piezoelectric film 11.

Thereafter, as shown in FIG. 3 (III), the upper drive electrode film 12 is formed on the piezoelectric film 11. In this example, the upper drive electrode 12 is formed of 100 nm-thick platinum by a sputtering film forming method.

Next, as shown in FIG. 4 (I) and FIG. 5 (I), an appropriate etching mask (not shown) is used to match the upper drive electrode 12 and the piezoelectric film 11 to the position where the pressure chamber 2 is formed. ) Is performed, etching is formed into a predetermined separation shape.

Next, after the lower drive electrode 10 and the silicon dioxide film 21 are similarly subjected to an appropriate etching mask (not shown),
It was formed in a predetermined shape (such as a connection terminal with an external drive circuit).
These etchings were performed by vapor phase etching using argon gas.

As shown in FIGS. 4 (II) and 5 (II), a resin film is applied to the entire surface after patterning, and then openings such as contact holes 34 are formed and wiring electrodes are arranged. . Fluorine resin is used for the resin film by solvent coating method
It was applied to a thickness of m. Gold was used for the wiring electrode 33.

After forming a protective film (not shown because it is complicated) against various chemicals to be dipped in a later step on the side of the substrate 20 on which the piezoelectric film is formed, at least the pressure chamber or pressure on the opposite surface is formed. A window 22 is formed by etching the silicon dioxide film 21 with hydrogen fluoride in a region including the chamber partition wall. After that, an anisotropic etching solution, for example, a concentration of 17 kept at 80 ° C.
Anisotropy etching is performed using an aqueous solution of potassium hydroxide of about 10% so that the silicon single crystal substrate 20 penetrates to the upper surface of the substrate. Since the fluorine-based resin film 32 is sparingly soluble in this potassium hydroxide, the supporting portion is not affected by the etching solution from the pressurizing chamber side. Alternatively, the pressure chamber may be formed by using an anisotropic etching method using an active gas such as parallel plate reactive ion etching. A flow path such as the ink pressurizing chamber is formed by this process (FIGS. 4 (III) and 5 (III)).

In consideration of resistance to potassium hydroxide, resin such as polysulfone is also suitable for the resin film 32.

An ink jet recording head is completed by bonding and assembling a separate nozzle plate or the like to the pressure chamber substrate formed by the above steps.

When the ink jet recording head formed as described above is compared with that of the conventional structure, the conventional product is
The maximum deflection amount was 200 nm when a voltage of 20 V was applied, whereas the product of the present invention could obtain a large deformation amount of 300 nm.

Further, as shown in FIG. 6, when the cross section of the piezoelectric film 11 is covered with the resin film 32, the dielectric breakdown electric field of the piezoelectric strain generating portion 30 was 90 V / μm in the conventional case of 60 V / μm.
Improved to μm.

In addition, as shown in FIG. 2, when the cross section of the piezoelectric film 11 and the upper driving electrode 12 were covered with the resin film 32, the durability life in a high humidity environment was improved by 40%.
It is considered that this is because the upper drive electrode 12 was as thin as 100 nm and moisture in the environment had penetrated to the piezoelectric film, but was blocked by the resin film.

By using the manufacturing method as in this example, it is possible to select different materials for the elastic film forming the piezoelectric strain generating section 30 and the material for the supporting section 31, and thus the degree of freedom in design according to the purpose of the actuator. Can be expanded. In particular, since the support member material is formed after the piezoelectric film baking step, high temperature heat resistance is not required.

In this example, the PZT-based material is used as the piezoelectric film, but other metal oxides such as niobium oxide, nickel oxide, and magnesium oxide may be added to this system, or materials other than the PZT-based material may be used. The present invention is effective.

Although the application example of the ink jet recording head has been described in the present embodiment, the displacement or pressure generator or the detector of the minute other element applying the characteristics of the thin film piezoelectric material such as the minute optical device, the minute pressure detector, etc. The present invention is effective for all.

[0038]

According to the present invention, a resin film is used for the support portion of the pressure generating chamber, and a material different from that of the support portion is used for the elastic film, so that the displacement characteristics and the reliability are prevented from being lowered and the reliability is improved. It is possible to realize an ink jet recording head with high characteristics.

[Brief description of drawings]

FIG. 1 is a perspective view of an inkjet recording head according to an embodiment of the present invention.

FIG. 2 is a sectional view of an ink jet recording head according to an embodiment of the present invention.

FIG. 3 is a diagram showing a manufacturing process of the ink jet recording head in the embodiment of the present invention.

FIG. 4 is a diagram showing a manufacturing process of the ink jet recording head in the embodiment of the present invention.

FIG. 5 is a diagram showing a manufacturing process of the ink jet recording head in the embodiment of the present invention.

FIG. 6 is a sectional view of an ink jet recording head according to an embodiment of the present invention.

FIG. 7 is a diagram illustrating a structure of a conventional ink jet recording head.

[Explanation of symbols]

1 Pressurized chamber substrate 2 Pressurization chamber 3 common channels 5 Pressure generation membrane 6 nozzle plate 7 Ink ejection nozzle 8 wiring board 9 supply routes 10 Lower drive electrode 11 Piezoelectric film 12 Upper drive electrode 14 Drive voltage source 18 Pressure chamber partition 20 Silicon single crystal substrate 21 Silicon dioxide film 24 Piezoelectric film precursor 29 Radiation source 30 Piezoelectric strain generator 31 Piezoelectric strain generator support 32 resin film 33 wiring electrode 34 contact holes 90 base

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41J 2/045 B41J 2/055 B41J 2/16 H01L 41/09

Claims (8)

(57) [Claims] 1. An ink pressurizing chamber arranged in a row on a silicon single crystal substrate through a partition wall, and one wall of the pressurizing chamber, which covers and covers one side of the pressurizing chamber and is suspended and fixed by the partition wall. An ink jet recording head having a pressure generating film arranged in a line and an ink discharge nozzle communicating with each of the pressurizing chambers, and discharging ink by pressure generated by flexural deformation of the pressure generating film. Wherein the pressure generating film includes a piezoelectric film, a lower and upper drive electrode with the piezoelectric film interposed therebetween, and an elastic film laminated on either the lower or upper drive electrode. A strain generating part and a supporting part for supporting the piezoelectric strain generating part on the partition wall, the supporting part being made of a polymer resin film, and the elastic film being made of a material different from that of the supporting part. Inkjet recording Head. 2. The ink jet recording head according to claim 1, wherein at least one of the lower drive electrode and the upper drive electrode has the performance of an elastic film together with an elastic film. 3. The ink jet recording head according to claim 1, wherein the supporting portion is made of a fluororesin film. 4. The ink jet recording head according to claim 1, wherein the supporting portion is made of a polysulfone film. 5. The support section is formed by sandwiching at least the piezoelectric film of the piezoelectric strain generating section between the lower and upper drive electrodes and covering the exposed cross section. The inkjet recording head according to any one of 1. 6. The support portion is formed by sandwiching at least the piezoelectric film of the piezoelectric strain generating portion between the lower and upper drive electrodes and covering the exposed section and the surface of the upper electrode. The inkjet recording head according to any one of claims 1 to 4. 7. The support portion covers at least a part of a cross section of the piezoelectric film of the piezoelectric strain generating portion which is sandwiched between the lower and upper drive electrodes of the piezoelectric film and covers a part of the exposed cross section, and the upper surface of the support portion and the external portion The ink jet recording head according to any one of claims 1 to 6, wherein a wiring electrode for connection with a drive circuit is arranged. 8. A piezoelectric film, a lower and upper drive electrode with the piezoelectric film interposed therebetween, and an elastic film laminated on either the lower or upper drive electrode, on one surface of a silicon single crystal substrate. A step of forming a film forming the piezoelectric strain generating part having, a step of forming the piezoelectric strain generating part by photoetching thereafter, and a step of forming a film forming a supporting part supporting the piezoelectric strain generating part on a partition wall. An ink jet comprising: a step of forming a film and forming it into a predetermined shape; and a step of forming a pressurization chamber arranged in a row in the silicon single crystal substrate through the partition wall by etching on the silicon single crystal substrate. Method of manufacturing a recording head.