JPH06198877A - Ink jet printing head and its production - Google Patents

Abstract

PURPOSE:To obtain a multi-nozzle ink jet printing head having a high reliability and little variation in characteristics and realizing a high printing quality at a low cost. CONSTITUTION:In an ink jet printing head for delivering ink outside out of a nozzle opening 102 on a drive signal transmitted to a piezoelectric element 101, a plurality of nozzle openings 102 are arranged on a single continuous nozzle plate 105, piezoelectric elements 101 obtained by machining a plurality of bulk piezoelectric bodies are disposed correspondingly to the nozzle openings 102, and a machining area 303 is provided at a boundary 301 between adjacent bulk piezoelectric bodies. Furthermore, after the two or more bulk piezoelectric bodies are arranged in a nozzle arranging direction, nozzle surfaces of the bulk piezoelectric bodies are ground or lapped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head used in an ink jet printer and a method for manufacturing the print head.

[0002]

2. Description of the Related Art A conventional ink jet print head is
As shown in Japanese Examined Patent Publication No. 60-8953, a plurality of nozzle openings are formed on the wall surface of a container constituting an ink tank, and piezoelectric elements are arranged so that the expansion and contraction directions are aligned so as to face each nozzle opening. It is constructed and set up. This print head applies a drive signal to a piezoelectric element to expand and contract the piezoelectric element, and the dynamic pressure of ink generated at this time causes ink droplets to be ejected from nozzle openings to form dots on printing paper.

In a print head of this type,
It is desirable that droplet formation efficiency and flight force are large. However, since the unit length of the piezoelectric element and the expansion / contraction rate per unit voltage are extremely small, it is necessary to apply a high voltage in order to obtain the flying force required for printing, which complicates the drive circuit and electrical insulation measures. The problem is that

In order to solve such a problem, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Laid-Open No. 3-295269, there has been proposed a piezoelectric element for an inkjet print head in which electrodes and piezoelectric materials are alternately laminated in a sandwich shape. With this piezoelectric element, the distance between the electrodes can be made as small as possible, so that there is an effect that the voltage of the drive signal can be lowered.

However, any piezoelectric element is a fired body, and the length of the bulky piezoelectric body that can be fired is at most 30 to 30 in consideration of variations in characteristics, warpage of the bulky piezoelectric body during firing, and deformation such as waviness. The limit was 50 mm, and it was difficult to increase the size of the print head (line head) with one sheet of bulk piezoelectric material.

As a structure capable of avoiding such a problem, Japanese Patent Publication No. 3-58917 discloses a print head structure in which a line head is composed of a plurality of head units.

[0007]

However, when a plurality of head units are arranged to form a line head, it becomes difficult to secure the nozzle position accuracy between the head units, and the joints between the units make it possible to vertically print the printed matter. This was a factor causing unevenness such as stripes.

An object of the present invention is to provide at low cost an ink jet type print head of high print quality, in which piezoelectric elements can be easily arranged in high density and variation in characteristics is small.

[0009]

In order to solve the above-mentioned problems, in the present invention, an ink jet type print head in which ink is discharged to the outside from a nozzle opening by a drive signal to a piezoelectric element, A plurality of the nozzle openings are arranged on one continuous nozzle plate, and the piezoelectric elements are arranged so as to correspond to the nozzle openings by processing a plurality of bulk piezoelectric bodies. The boundary of the bulk piezoelectric body is a processed region.

Furthermore, in the method of manufacturing an ink jet type print head, the piezoelectric element is characterized in that a plurality of bulk piezoelectric bodies are arranged in a nozzle array direction and then the nozzle surface side of the bulk piezoelectric bodies is ground. Further, the piezoelectric element is characterized in that a plurality of bulk-shaped piezoelectric bodies are arranged in the nozzle arrangement direction and then the nozzle surface side of the bulk-shaped piezoelectric bodies is lapped.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a top view of an ink jet type print head according to the present invention, FIG. 2 is a sectional view taken along the line AA in FIG. 1, and FIG. 3 is an enlarged view of a portion C in FIG. FIG. 4 is a sectional view taken along the line BB in FIG.

In FIG. 1 to FIG. 4, the ink passes through the ink flow passage 110 from the ink supply hole 113 formed in the ink flow passage plate 106, and the partition plate 104 and the nozzle plate 105.
And is supplied to each ink chamber 302 constituted by the vibration plate 103.

A piezoelectric element 10 is provided corresponding to each ink chamber 302.
1 and the ink opening 102 are arranged, the piezoelectric element 101 is arranged on the base plate 107, and the ink is ejected from the nozzle opening 102 by repeating the expansion and contraction motion by the electric signal from the printer main body via the FPC 108.

First, a method of manufacturing a piezoelectric element will be described.

In FIG. 5, a piezoelectric material 50, such as a lead zirconate titanate-based composite perovskite ceramic, prepared in the form of a green sheet or a paste on a plate 501.
2 is applied, and as shown in FIG. 6, a first internal electrode material 601 to be one of the electrodes is formed on the surface of the same by using a thick film printing method with a conductive paste in which Ag, Pd, etc. are adjusted.
Further, in FIG. 7, the piezoelectric material 502 is applied to the surface of the internal electrode material layer 601, and the internal electrode material 701 to be the other electrode is applied to the upper surface by the above method as shown in FIG. After that, the internal electrode material layer and the piezoelectric material are repeatedly applied by the above-mentioned method by the required number of layers, and the layers are dried in FIG.

This is fired under pressure, and external electrodes 1001 are formed on the surface where the conductive layers 601 and 701 are exposed as shown in FIG. 10 and dried to form a rectangular parallelepiped bulk piezoelectric material. A body 1101 is formed. The external electrode may be formed by either a thick film process or a thin film process, but the thin film process is more suitable in terms of film thickness uniformity and adhesion strength. Further, here, since the thickness dimension at the time of printing shrinks at the time of firing, it is necessary to print each layer thicker than a desired dimension in consideration of the shrinkage rate in advance. This shrinkage rate is about 10 to 50%, although it depends on the selected internal electrode material, piezoelectric material, and firing conditions.

Here, the bulk piezoelectric body 1101 is deformed such as warped or undulated due to shrinkage variation during firing, etc., and causes cracks or cracks when pressing or adhering to the base plate 107 in the next step. Becomes Therefore, the length of the bulk piezoelectric body 1101 is limited to 30 to 50 mm. The present invention is characterized in that a line head is configured by arranging a plurality of bulk piezoelectric substances 1101 having a size of 30 to 50 mm.

The manufacturing process of the line head will be described below.

Bulk-shaped piezoelectric body 1 manufactured as described above
101 has variations in characteristics such as piezoelectric constants due to variations in printing accuracy and firing variations of the internal electrode material layers 601 and 701.
For this reason, the capacitance and the like are measured in advance and sorted by class. Then, as shown in FIG. 11 and FIG.
A bulk-shaped piezoelectric material 1101 is arranged and adhered and fixed on a base plate 107 in which a wiring pattern 1102 for giving a drive signal from the printer body to 1 is formed at the same pitch as the nozzle opening pitch. Here, the material of the base plate 107 is a material that does not deteriorate the vibration characteristics of the piezoelectric element 101, that is, the specific acoustic impedance (1/2) of the product of the Young's modulus E of the material and the density ρ of the material. It is desirable that ρ × E) ^ 1/2 be larger than the intrinsic acoustic impedance of the piezoelectric element.

Further, in this embodiment, the bulk piezoelectric bodies 1101 are arranged in a line on the base plate 107 in order to downsize the head and simplify the electric circuit (no need for a delay circuit or the like).

The length of the bulk piezoelectric material 1101 in the nozzle array direction at this time is determined by the boundary 1103 of the bulk piezoelectric material.
Is lost when the bulk piezoelectric body 1101 is pitch-processed, that is, the length L of the bulk piezoelectric body 1101 is
When the nozzle arrangement pitch is P and the number of nozzles is n, it is necessary to set L = P × n. This means that if the boundary when arranging the bulk-shaped piezoelectric bodies 1101 at the portion of the piezoelectric element 101 comes, variation in displacement characteristics occurs within one piezoelectric element. Furthermore, since the displacement characteristics are different, stress concentrates at the boundary and there is a risk of destruction.

In this embodiment, eight line heads each having a nozzle pitch of 8/300 inches and 512 nozzles are arranged with 64 nozzles each consisting of one bulk-shaped piezoelectric body. Therefore, the length L of one bulk-shaped piezoelectric body is as follows. And

L = 8/300 × 25.4 × 64 = 43.349 (mm) Here, the gap at the boundary 301 of the bulk piezoelectric body must be controlled by the processing region width 303 to be cut. If the side surface of the machined tooth slightly touches the side surface of the bulk piezoelectric body 1101, chipping occurs on the side surface of the bulk piezoelectric body 1101. For this reason, it is desirable to set the gap at the boundary 301 of the bulk piezoelectric material to be ¼ or less of the processing region width 303.

At this time, the bulk-shaped piezoelectric bodies 1101 on the base plate 107 have variations in height between the bulks due to variations in the thickness of the adhesive layer at the time of bonding and initial variations in the thickness of the bulk-shaped piezoelectric bodies 1101. . This height variation results in a variation in the gap between the nozzle opening 102 and the piezoelectric element 101, which affects the flight characteristics of the ink. In order to avoid this problem, in this embodiment, as shown in FIG. 11, the upper surface of the bulk piezoelectric element 1101 was ground with a dicing saw using a diamond blade 1104 to make the height uniform. In addition to top surface grinding, top surface lapping is effective as a method for making the height uniform.

Here, since the displacement amount of the laminated piezoelectric element is proportional to the electric field strength applied to one layer of the internal electrode, it is effective to reduce the thickness of the internal piezoelectric material layer in order to obtain a large displacement at a low voltage. is there. However, if the outermost layer is also thinned similarly to the internal electrode layer, the internal electrode is exposed during the top surface grinding unless the height variation of each bulk piezoelectric element is suppressed to the thickness of the outermost layer or less. Therefore, the bulk-shaped piezoelectric element 1101 at this time has a height of the bulk-shaped piezoelectric element 1101 as shown in FIG. 13 in order to prevent the internal electrodes 601 and 701 from being exposed during grinding or lapping. Nozzle opening side of piezoelectric body 1101 (uppermost outermost layer) 13
01 or, as shown in FIG. 14, a bulk piezoelectric body 11
01 outermost layer 1301 and piezoelectric element fixing portion side 140
It is desirable to make 1 (lower outermost layer) thicker than the internal piezoelectric material layer.

In this embodiment, the inner piezoelectric material 502 has a thickness of 35 μm, the outermost layer upper portion 1301 and the outermost layer lower portion 1
The thickness of 401 was 105 μm by stacking three green sheets having a thickness of 35 μm. Thus, in order to simplify the green sheet manufacturing process, the thickness of the outermost layers 1301 and 1401 may be set to an integral multiple of the thickness of the internal piezoelectric material layer so that the internal piezoelectric material 502 can be laminated. desirable.

Further, as shown in FIG. 2, the raw material 1501 of the pillar 114 which serves as a reference for alignment when laminating and adhering the vibrating plate 103, the partition plate 104 and the nozzle plate 105 to both ends of the base plate is shown in FIGS. Bond as shown in 16.
After that, as shown in FIGS. 17 and 18, a conductive material 1701 such as silver paste is applied to the external electrode 1001 of the bulk piezoelectric body 1101, the wiring pattern 1102 on the base plate 107, and the common electrode 1201 to establish conduction. . Thereafter, as shown in FIGS. 19 and 20, the bulk piezoelectric body is processed according to the wiring pattern 1102 to form the piezoelectric element 101, the dummy piezoelectric element 115, and the reference column 114, thereby obtaining the base plate unit 1901.

In the present embodiment, since the dicing saw using the diamond blade is used as the processing method, the piezoelectric element 101 with respect to the reference pillar 114 is raised by simultaneously performing the arrangement processing of the piezoelectric elements 101 and the formation processing of the reference pillar 114. I was able to arrange it with accuracy. In addition, the base plate 107 is 50 to 10
It was possible to completely electrically separate the conductive material 1701 by cutting with 0 μm.

Next, as shown in FIG. 21, the ink flow path plate 1
Insert the base plate unit 1901 into the adhesive
And the flow path plate unit 2102 is obtained. Here, in order to secure the flatness of the upper surface of the ink flow path plate 106 and the upper surface of the piezoelectric element 111, the base 2101 is used.

Next, as shown in FIG. 22, the flow path plate unit 2102 having the upper surface coated with an adhesive is fixed to the base 2201, and the reference holes formed in the diaphragm 103 are inserted into the reference columns 114 for alignment. To do. After that, the weight 2202 is applied with pressure to bond and fix in a high temperature atmosphere as needed. Here, the dummy piezoelectric element 115 is left as a receiver for the partition plate 104. This work is repeatedly laminated and adhered to the partition plate 104 and the nozzle plate 101 having the nozzle openings 102. Then, the FPC 108 is mounted to obtain the ink jet type print head shown in FIGS.

Here, in order to transmit the driver signal from the printer main body to each piezoelectric element through the FPC 108, the FPC mounting is required to have a high density mounting with a large number of pins.

As a method for avoiding this, as shown in FIG. 23, the driver IC 112 is mounted on the base plate. According to this, only the signal line for driving the driver IC is sufficient for the FPC, and the FPC mounting is dramatically facilitated.

In this embodiment, the piezoelectric element 101 is an example in which a laminated piezoelectric element in the d33 direction utilizing displacement in the same direction as the electric field direction is used, but as shown in FIG. D31 direction piezoelectric element 24 using displacement
01 may be used.

[0034]

As described above, in the ink jet type print head in which the ink is discharged from the nozzle opening by the drive signal to the piezoelectric element,
A plurality of the nozzle openings are arranged on one continuous nozzle plate, and the piezoelectric elements are arranged so as to correspond to the nozzle openings by processing a plurality of bulk piezoelectric bodies. At this time, by making the boundary between the adjacent bulk-shaped piezoelectric bodies a processing region, the joint is eliminated in the piezoelectric element, and after the plurality of bulk-shaped piezoelectric bodies are arranged in the nozzle array direction, the bulk-shaped piezoelectric body is formed. By grinding or lapping the nozzle surface side of the nozzle, and managing the gap between the nozzle opening and the piezoelectric element, an inkjet print head with high print quality that is highly reliable and has few characteristic variations even with multiple nozzles. Can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a top view showing the structure of an inkjet print head of the present invention.

FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1 showing the structure of the inkjet print head of the present invention.

FIG. 3 is an enlarged view of portion C in FIG. 2 showing the structure of the inkjet print head of the present invention.

FIG. 4 is a cross-sectional view taken along the line BB in FIG. 1 showing the structure of the inkjet print head of the present invention.

FIG. 5 is a cross-sectional view showing the manufacturing process of the inkjet print head of the present invention.

FIG. 6 is a cross-sectional view showing a manufacturing process of the inkjet print head of the present invention.

FIG. 7 is a cross-sectional view showing a manufacturing process of the inkjet print head of the present invention.

FIG. 8 is a cross-sectional view showing a manufacturing process of the ink jet print head of the present invention.

FIG. 9 is a cross-sectional view showing a manufacturing process of the ink jet print head of the present invention.

FIG. 10 is a cross-sectional view showing the manufacturing process of the inkjet print head of the present invention.

FIG. 11 is a view showing a manufacturing process of the ink jet print head of the present invention.

FIG. 12 is a cross-sectional view showing the manufacturing process of the inkjet print head of the present invention.

FIG. 13 is a cross-sectional view showing the manufacturing process of the inkjet print head of the present invention.

FIG. 14 is a cross-sectional view showing a manufacturing process of the ink jet print head of the present invention.

FIG. 15 is a diagram showing a manufacturing process of the inkjet print head of the present invention.

FIG. 16 is a cross-sectional view showing the manufacturing process of the inkjet print head of the present invention.

FIG. 17 is a diagram showing a manufacturing process of the inkjet print head of the present invention.

FIG. 18 is a cross-sectional view showing a manufacturing process of the ink jet print head of the present invention.

FIG. 19 is a diagram showing a manufacturing process of the ink jet type print head of the present invention.

FIG. 20 is a cross-sectional view showing the manufacturing process of the inkjet print head of the present invention.

FIG. 21 is a cross-sectional view showing the manufacturing process of the inkjet print head of the present invention.

FIG. 22 is a cross-sectional view showing the manufacturing process of the inkjet print head of the present invention.

FIG. 23 is a cross-sectional view showing an embodiment of the ink jet print head of the present invention.

FIG. 24 is a cross-sectional view showing an embodiment of the ink jet print head of the present invention.

[Explanation of symbols]

 101 Piezoelectric element 102 Nozzle opening 103 Vibrating plate 104 Partition plate 105 Nozzle plate 106 Ink flow channel plate 107 Base plate 108 FPC 109 Electrode 110 Ink flow channel 301 Bulk piezoelectric boundary 302 Ink chamber 303 Processing area

Claims (6)

[Claims] 1. An ink jet print head in which ink is ejected to the outside from a nozzle opening by a drive signal to a piezoelectric element, the plurality of nozzle openings are arranged on one continuous nozzle plate. Has been done,
An ink jet print head characterized in that the piezoelectric element is arranged so as to process a plurality of bulk-shaped piezoelectric bodies so as to correspond to a nozzle opening, and a boundary between adjacent bulk-shaped piezoelectric bodies is a processing region. . 2. The piezoelectric element is a laminated piezoelectric element,
The outermost layer piezoelectric material on the nozzle opening side, or the outermost layer piezoelectric material on both the nozzle opening side and the piezoelectric element fixing portion side, is thicker than the internal piezoelectric material layer thickness. 1. The inkjet print head according to 1. 3. The ink jet print head according to claim 2, wherein the outermost layer piezoelectric material thickness of the laminated piezoelectric element is an integral multiple of the inner piezoelectric material layer thickness. 4. A method for manufacturing an ink jet type print head, wherein ink is discharged to the outside from a nozzle opening by a drive signal to a piezoelectric element, wherein the nozzle opening is formed on one continuous nozzle plate. A method for manufacturing an ink jet print head, wherein a plurality of piezoelectric elements are arranged, and a plurality of bulk piezoelectric elements are arranged in a nozzle array direction, and then the nozzle surface side of the bulk piezoelectric elements is ground. . 5. The ink jet print head according to claim 4, wherein the piezoelectric element is formed by arranging a plurality of bulk piezoelectric elements in a nozzle array direction and then lapping the nozzle surface side of the bulk piezoelectric elements. Manufacturing method. 6. The ink jet print head according to claim 1, wherein the ink jet print head is a line head having a length substantially equal to a recording width of a recording medium.