JPH06198876A - INKJET PRINT HEAD AND METHOD OF MANUFACTURING THE SAME - Google Patents

Abstract

(57) [Summary] [Purpose] To provide, at low cost, an inkjet printhead of high printing quality, which has high reliability even with a large number of nozzles and has little characteristic variation. In an ink jet type print head in which ink is discharged to the outside from a nozzle opening portion 102 by a drive signal to a piezoelectric element 101, the nozzle opening portions 102 are provided on a single continuous nozzle plate 105. The piezoelectric elements 101 are arranged in a row and the nozzle openings 102 are arranged.
Piezoelectric element 1 processed by processing bulk piezoelectric material to correspond to
01 and the driver IC 202 are mounted on the base plate unit after the displacement characteristic classification is performed and a plurality of the base plate units are arranged. The manufacturing method uses the bulk piezoelectric body as the base plate 1.
No. 07, the nozzle surface side of the bulk piezoelectric body is 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 element is such that a bulk piezoelectric body corresponds to the nozzle openings on a base plate on which a piezoelectric element driver IC is mounted. And processed and arranged, the piezoelectric element,
A plurality of base plate units including the driver IC and the base plate are arranged.

Further, the base plate unit is characterized in that the displacement characteristics of the piezoelectric element are classified for each unit, and a plurality of base plate units having equivalent displacement characteristics are arranged.

Further, the piezoelectric element is a laminated piezoelectric element, and 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 has a thickness of It is characterized in that it is thicker than the internal piezoelectric material layer thickness. Further, the outermost layer piezoelectric material thickness of the laminated piezoelectric element is an integral multiple of the internal piezoelectric material layer thickness. Further, the piezoelectric element is characterized in that the bulk piezoelectric body is arranged on the base plate and then the nozzle surface side of the bulk piezoelectric body is ground or lapped.

[0012]

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 FIGS. 1 to 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.

The piezoelectric element 10 is provided in correspondence with 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.

Referring to 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 conductive paste in which Ag, Pd, etc. are adjusted by a thick film printing method. 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 surfaces 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 variations 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 the line head is configured by arranging a plurality of base plate units in which the bulk piezoelectric body 1101 of 30 to 50 mm is arranged.

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

First, as shown in FIG. 11 and FIG. 12 which is a cross-sectional view of FIG. 11, piezoelectric element drive wiring for applying a drive signal to the piezoelectric element 101 from the driver IC formed at the same pitch as the nozzle opening pitch. A pattern 1102, an IC driving wiring pattern 1103 for giving a driving signal from the printer body to the driver IC, and a common electrode 1201.
13 and the driver IC 202 is mounted on the IC mounting portion 1101 on the base plate 107 by the wire bonding method, the flip chip method or the like as shown in FIG. 13 and the sectional view of FIG. do.

After that, as shown in FIG. 15 and FIG. 16 which is a cross-sectional view of FIG. 15, a bulk piezoelectric body 1101 is disposed on the base plate 107, and is adhered and fixed, and then the bulk piezoelectric body 110.
A conductive material 1502 is applied to electrically connect 1 to the wiring pattern on the base plate.

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 natural acoustic represented by the product of the Young's modulus E of the material and the density ρ of the material to the power of 1/2. It is desirable that the impedance (ρ × E) ̂1 / 2 be larger than the specific acoustic impedance of the piezoelectric element.

The length L of the bulk piezoelectric body 1101 in the nozzle array direction at this time is the number of output bits n of one driver IC, the number m of driver ICs, and the piezoelectric element 1.
If the arrangement pitch is 01, it is desirable that L = P × n × m.

This is because if the number n of driver IC output bits on one base plate is different from the number of piezoelectric elements, it is necessary to secure electrical continuity between the base plates to each piezoelectric element. Electrical conduction between the two becomes difficult because the wiring has a high density. Therefore, in this embodiment, eight line heads each having a nozzle pitch of 8/300 inches and 512 nozzles are arranged by 64 bits in one driver IC.

Here, in consideration of the bonding accuracy of the base plate 107 and the bulk piezoelectric body 1101, the length L of one bulk piezoelectric body is L> 8/300 × 25.4 × 64 = 43.349 (mm ) Is satisfied, and both ends of the base plate 107 and the bulk piezoelectric body 1101 are simultaneously cut at the time of forming the piezoelectric element array in the subsequent process as shown in FIG.
The positional accuracy of the piezoelectric element 101 from the end face of 7 is secured. That is, the length L after cutting is L = 43.349 mm
Has become.

Further, when the bulk-shaped piezoelectric bodies 1101 on the base plate 107 are obliquely bonded due to variations in the thickness of the bonding layer at the time of bonding, the initial shape of the bulk-shaped piezoelectric bodies 1101, etc., when the piezoelectric element 101 is formed. There is a risk of height variations (steps). This height variation affects the ink ejection characteristics and the nozzle opening 102 and the piezoelectric element 1.
This causes the gap with 01 to vary.

In order to avoid this problem, in this embodiment, the upper surface of the bulk piezoelectric element 1101 was ground by a dicing saw using a diamond blade to make the height uniform. In addition to top surface grinding, top surface lapping is effective as a method for making the height uniform.

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 bulk-shaped piezoelectric element 1101 in consideration of height variation or more in advance so that the internal electrodes 601 and 701 are not exposed during grinding or lapping. Nozzle opening side of piezoelectric body 1101 (uppermost outermost layer) 17
01 or, as shown in FIG. 18, a bulk piezoelectric body 11
01 outermost layer 1701 and piezoelectric element fixing portion side 180
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 1701 and the outermost layer lower portion 1
The thickness of 801 was 105 μm by laminating three 35 μm green sheets. Thus, in order to simplify the green sheet manufacturing process, the thickness of the outermost layers 1701 and 1801 is set to an integral multiple of the thickness of the internal piezoelectric material layer so that the internal piezoelectric material 502 can be laminated. Things are desirable.

Then, as shown in FIG. 19 and FIG. 20 which is an enlarged view of the D portion of FIG. 19, the bulk piezoelectric body is processed according to the wiring pattern 1102 to form the piezoelectric element 101 and the dummy piezoelectric element 115. By the base plate unit 1901
To get Also, the conductive material 1502 could be completely electrically separated by cutting the base plate 107 by 50 to 100 μm. Here, in the present embodiment, as described above, in order to secure the positional accuracy of each piezoelectric element 101 from the end face of the base plate 107, a dicing saw using a diamond blade is used as a processing method and the end face of the base plate and the bulk piezoelectric material are used. The body end surface was processed at the same time to provide a reference surface 1902. Here, since there is a limit to the dipable depth L2 of the dicing process, both ends of the base plate forming the reference surface 1902 are formed in a convex shape as shown in FIG.

In this embodiment, a line head having a nozzle pitch of 8/300 inches and 512 nozzles is used as a single driver IC.
It was decided to arrange 64 bits each, that is, 8 base plate units. Here, in order to secure the positional accuracy of the vibrating plate 103, the partition plate 104, the nozzle plate 105, and each piezoelectric element 101 in the subsequent process, units arranged at both ends of the base plate unit arranged in eight as shown in FIG. 2101,
As shown in FIG. 21 and FIG. 22, the reference pillar 114 is formed in 2201 by processing the bulk piezoelectric material and the reference pillar material at the same time when the base plate is processed.

As shown in FIG. 23, the base plate units 1901, 2101, and 2201 obtained as described above are inserted into the ink flow path plate 106 while the reference surfaces formed on the respective units are in contact with each other. After that, as shown in FIG. 24, it is pressed against the base 2401 and adhered so that the upper surface of the ink flow path plate 106 and the upper surface of the piezoelectric element 101 become uniform.
A flow path plate unit 2402 as shown in FIG. 25 is obtained.

Here, as described above, since the piezoelectric element 101 is a fired body in which the internal electrodes are thick-film printed, the characteristics vary depending on the internal electrode printing accuracy, firing state, and manufacturing lot. Therefore, the displacement characteristic of each piezoelectric element 101 after processing the bulk piezoelectric body was measured for each base plate unit and classified into several preset classes according to the displacement characteristic. After that, one head was constructed by arranging base plate units of the same class. In this way, the preliminary inspection, which was conventionally performed with a substitute value such as capacitance, can be managed by a direct factor that influences the ink ejection characteristics, that is, the displacement of the piezoelectric element fixed to the base plate.

As a result, the displacement characteristics between the units can be made uniform with high precision, so that an ink jet type print head having stable ink ejection characteristics and excellent print quality can be obtained.

Next, as shown in FIG. 26, a flow path plate unit 2102 having an adhesive applied on the upper surface is fixed to a base 2601, and a reference hole previously provided in the vibration plate 103 is inserted into the reference column 114 for alignment. To do. After that, pressure is applied with a weight 2602, and if necessary, adhesive bonding is performed in a high temperature atmosphere. 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.

Further, in this embodiment, the nozzle row 2701 is arranged in one row as shown in FIG. 27 in order to miniaturize the head and simplify the electric circuit (no need for a delay circuit etc.). As shown in FIG. 28, the first nozzle row 2801 and the second nozzle row 2802 can be arranged in a staggered arrangement for each base plate unit. Even with this structure, since the present invention is configured with a single nozzle plate, the nozzle position accuracy at the boundary of the base plate unit is guaranteed at the time of manufacturing the nozzle plate, so that high print quality with no vertical stripes is generated. You can get an inkjet head.

In this embodiment, an example in which one driver IC is mounted on one base plate is shown.

However, the number of output bits of the driver IC,
Depending on the manufacturable length of the bulk piezoelectric body, a plurality of drivers I can be mounted on one base plate as long as the variation in characteristics can be tolerated.
It is also possible to implement C.

In this embodiment, the wire bonding method and the flip chip method are introduced as the IC mounting method on the base plate, but as shown in FIGS. 29 and 30, TAB is used.
The TAB unit 2901 mounted by the (Tape Automated Bonding) method is mounted on the base plate 107.
You may take the structure connected to. Since the TAB method is easy to inspect at the time of mounting the IC, it can be expected to improve the manufacturing yield.

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 31 utilizing displacement
01 may be used.

[0041]

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 element is formed by processing a bulk piezoelectric body on the base plate on which the piezoelectric element driver IC is mounted so as to correspond to the nozzle openings. The piezoelectric element,
A plurality of base plate units including the driver IC and the base plate were arranged after performing characteristic classification.

Furthermore, the piezoelectric element is a laminated piezoelectric element, and the thickness of the outermost layer piezoelectric material on the nozzle opening side or both the outermost layer piezoelectric material on both the nozzle opening side and the piezoelectric element fixing portion side is small. The thickness is made thicker than the thickness of the internal piezoelectric material layer, and the thickness of the outermost layer piezoelectric material of the laminated piezoelectric element is an integral multiple of the thickness of the internal piezoelectric material layer. After arranging the bulk piezoelectric body on the base plate, the nozzle surface side of the bulk piezoelectric body is ground or lapped. As a result, even with multiple nozzles, it was possible to provide an inkjet print head with high reliability and high print quality with little characteristic variation 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 cross-sectional view showing an embodiment of the ink jet print head of the present invention.

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

FIG. 21 is a diagram showing a manufacturing process of the ink jet print head of the present invention.

FIG. 22 is a diagram showing a manufacturing process of the ink jet print head of the present invention.

FIG. 23 is a perspective view showing a manufacturing process of the ink jet print head of the present invention.

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

FIG. 25 is a diagram showing a manufacturing process of the ink jet print head of the present invention.

FIG. 26 is a cross-sectional view showing the manufacturing process of the inkjet print head of the present invention.

FIG. 27 is a diagram showing an example of an ink jet print head of the present invention.

FIG. 28 is a diagram showing an example of an ink jet print head of the present invention.

FIG. 29 is a diagram showing an example of an ink jet print head of the present invention.

FIG. 30 is a cross-sectional view showing an embodiment of the ink jet print head of the present invention.

FIG. 31 is a cross-sectional view showing an embodiment of the inkjet 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 path plate 107 base plate 108 FPC 109 electrode 110 ink flow path

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication H01L 41/08 9274-4M H01L 41/08 D

Claims (7)

[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,
The piezoelectric element is divided and arranged so as to correspond to a nozzle opening on a base plate on which a piezoelectric element driving IC is mounted, and a base formed by the piezoelectric element, the driving IC, and the base plate. An ink jet type print head characterized by arranging a plurality of plate units. 2. The base plate unit according to claim 1, wherein displacement characteristics of the piezoelectric element are classified into units, and a plurality of base plate units having equivalent displacement characteristics are arranged. Inkjet print head. 3. 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. 4. The ink jet print head according to claim 3, wherein the thickness of the outermost layer piezoelectric material of the laminated piezoelectric element is an integral multiple of the thickness of the inner piezoelectric material layer. 5. A method of manufacturing an ink jet type print head, wherein ink is ejected 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 inkjet print head, wherein a plurality of piezoelectric elements are arranged, and a bulk piezoelectric body is arranged on the base plate, and then the nozzle surface side of the bulk piezoelectric body is ground. 6. The ink jet print head according to claim 5, wherein the piezoelectric element is formed by arranging the bulk piezoelectric body on the base plate and lapping the nozzle surface side of the bulk piezoelectric body. Manufacturing method. 7. 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.