JPH10100401A - Inkjet head - Google Patents

Abstract

(57) [Summary] [PROBLEMS] The cost is high and the reliability of the electrical connection is not sufficiently ensured. SOLUTION: A driver 60 is mounted on the back side of a substrate 13 to which a piezoelectric element 14 is bonded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head, and more particularly, to an ink jet head which discharges ink droplets by displacement of a piezoelectric element.

[0002]

2. Description of the Related Art An ink jet recording apparatus has almost no vibration and noise during recording, and is particularly easy to colorize.
In addition to a printer that outputs data from a digital processing device such as a computer, it is also used for facsimile machines, copiers, and the like. An ink jet head used in such an ink jet recording apparatus records an image on a recording medium by driving an actuator element such as a piezoelectric element or a heating resistor in accordance with a recording signal to eject and fly an ink droplet from a nozzle. Things.

[0003] As such an ink jet head,
For example, as described in Japanese Patent Application Laid-Open No. 8-142324, a plurality of laminated piezoelectric elements are joined and arranged in a plurality of rows on a substrate, and a frame member located around the piezoelectric elements is joined. A diaphragm having a diaphragm is laminated on these piezoelectric elements and the frame member, and a pressurized liquid chamber and a liquid chamber which are pressurized on the diaphragm by a laminated piezoelectric element through the diaphragm are provided. A liquid chamber forming member forming an ink supply path for supplying ink is laminated, and a nozzle plate having a nozzle formed thereon is further laminated on the liquid chamber forming member, and ink droplets are ejected from the nozzles by displacement of the laminated piezoelectric element. There are things that let me do that.

In such an ink-jet head, an end face electrode at both end faces of alternately connected internal electrodes of the laminated piezoelectric element and a driver (driving IC) for applying a required driving waveform to the laminated piezoelectric element. ) Must be electrically connected. Therefore, for example, in the ink jet head described in the above-mentioned publication, a common electrode pattern and an individual electrode (selection electrode) pattern are formed on a substrate on which a multilayer piezoelectric element is fixed, and the multilayer piezoelectric element and each electrode pattern are electrically conductive. Electrical connection with a conductive adhesive or the like, a flexible printed cable (hereinafter referred to as "FPC cable") is soldered to each electrode pattern of the board, and the FPC cable is connected to a driver to establish electrical connection. I am taking it.

[0005] As an ink jet head in which the FPC cable is used to electrically connect the piezoelectric element and the driver, for example, a head unit structure as shown in FIGS. 10 to 12 can be considered.

[0006] In brief, the ink jet head 101 has a plurality of laminated piezoelectric elements 103 arranged in two rows on a substrate 102 and a frame member 104 surrounding the periphery of the piezoelectric elements 103 joined thereto. The liquid chamber unit 105 is joined to the piezoelectric element 103 and the frame member 104 described above. Then, the substrate 102
Is mounted on a spacer member 106, and a PCB (driver IC) 107 is mounted on the spacer member 106.
Substrate 108 is incorporated, and PCB substrate 108 and substrate 1
The FPC cable 109 made of polyimide or the like is connected to the electrode pattern No. 02 by thermocompression bonding with solder.

[0007]

However, in order to connect the piezoelectric element of the ink jet head to the driving IC (driver) in this manner, an FPC cable and a PCB board on which the driver is mounted are required, and the FPC is required.
Since both ends of the cable must be connected to the electrode patterns of the PCB substrate and the head substrate, the number of connection points increases, and in addition, the FPC cable must be bent while assembling. It is difficult to obtain sufficient reliability of the dynamic connection, resulting in a large increase in cost.

The present invention has been made in view of the above points, and has as its object to reduce the cost and improve the reliability of the electrical connection of the head.

[0009]

In order to solve the above-mentioned problems, an ink jet head according to a first aspect of the present invention has a configuration in which a driver for driving the piezoelectric element is mounted on a substrate to which the piezoelectric element is bonded.

According to a second aspect of the present invention, in the inkjet head of the first aspect, the substrate is a glass epoxy substrate.

According to a third aspect of the present invention, in the inkjet head of the first aspect, the substrate is a ceramic substrate.

According to a fourth aspect of the present invention, there is provided an ink jet head according to any one of the first to third aspects, wherein the head is connected to the outside via a card edge type connecting portion provided on the substrate. .

According to a fifth aspect of the present invention, there is provided an ink jet head according to any one of the first to third aspects, wherein the head is connected to the outside via a flexible print cable.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic perspective view showing an example of an ink jet recording apparatus equipped with an ink jet head to which the present invention is applied.

In this ink jet recording apparatus, a carriage 4 is movably mounted on guide rails 2 and 3 laid horizontally on a frame 1, and a recording head 5 is mounted on the carriage 4 and driven by a driving source such as a motor (not shown). The carriage 4 can be moved in a direction indicated by an arrow A, and a sheet P, which is a recording medium (to which ink droplets are attached) set on a guide plate 6, is driven by a drive gear (not shown).
And a feed knob 9 rotated via a sprocket gear 8
The sheet is taken in by the platen 9 provided with a, and can be conveyed in the direction of arrow B by the peripheral surface of the platen 9 and the pressure roller 10 pressed against the platen 9.

In this ink jet recording apparatus, the paper P is conveyed in the sub-scanning direction (arrow B direction) while the recording head 5 (carriage 4) is moved and scanned in the main scanning direction (arrow A direction). Then, an image is printed on the paper P by ejecting ink droplets from the recording head 5.

Next, the ink jet head constituting the recording head 5 will be described with reference to FIGS. 2 is an exploded perspective view of the ink jet head, FIG. 3 is an enlarged cross-sectional view of a main part of the head, and FIG. 4 is an enlarged cross-sectional view of a main part of the head in a direction orthogonal to FIG.

This ink jet head has a drive unit 11 and a liquid chamber unit 12. The drive unit 11 arranges a plurality of laminated piezoelectric elements 14 in a row on an insulating substrate 13 made of ceramic, glass epoxy resin or the like, and surrounds the periphery of the plurality of piezoelectric elements 14. Two holes 15a, 15a
Are formed and joined. The plurality of piezoelectric elements 14 of the driving unit 1 include a driving unit 17 for applying a driving waveform and a non-driving unit 18 for not applying a driving waveform.
Are alternately configured.

Here, the piezoelectric element 14 is a laminated piezoelectric element as shown in FIGS. 3 and 4 and has a thickness of 20 to 50 μm.
An m / 1 layer of PZT (= Pb (Zr.Ti) O ₃ ) 20 and an internal electrode 21 made of silver / paradium (AgPd) having a thickness of several μm / 1 layer are alternately laminated. The drive voltage can be reduced by making the piezoelectric element a stacked type having a thickness of 20 to 50 μm / 1 layer. For example, an electric field strength of 1000 V / mm can be obtained with a pulse voltage of 20 to 50 V. The material used for the piezoelectric element is not limited to the above.

Each internal electrode 20 of the piezoelectric element 14 is connected to left and right external electrodes 22 and 23 made of AgPd or the like every other layer. On the other hand, as shown in FIG. 2, a common electrode pattern 24 for applying a drive waveform to the drive unit 17 is formed on the substrate 13 between the multilayer piezoelectric elements 14, 14. 17 is provided with an individual electrode pattern 25 for giving a selection signal.

Then, the end face electrodes 22 of each drive section 17 are connected to the common electrode pattern 24 via a conductive adhesive 26 such as silver paste, and the end face electrodes 23 are similarly connected to the conductive adhesive 2.
6, and is connected to an individual electrode (channel electrode) pattern 25. Note that the common electrode pattern 24 is
Is formed on the surface of the groove 33 formed at the center of the drive section 17 so as to establish conduction with each drive section 17.

The liquid chamber unit 12 includes a diaphragm 30 made of a metal or resin thin film, and photosensitive resin layers 31, 32, and 33 made of a three-layer photoresist film constituting a liquid chamber partition member. Metal forming the nozzle 34,
A nozzle plate 35 made of resin or the like is sequentially laminated,
It is formed by heat fusion. A pressurized liquid chamber 36 to which the nozzle 34 communicates with each of these members, common ink chambers 37, 37 located on both sides of the pressurized liquid chamber 36, and a common liquid chamber 3
Ink supply paths 38, 38 serving as fluid resistance portions for supplying ink from 7 to the pressurized liquid chamber 36 are formed.

The vibration plate 30 is composed of the laminated piezoelectric element 14 and the frame member 15 positioned or ground on the same plane.
The upper part is joined with an adhesive 39. The diaphragm 30 is formed of a diaphragm portion 41 serving as a displacement portion, a beam 42 joined to the non-driving portion 18 of the piezoelectric element 14, and a base 43 joined to the frame member 13.
Is an island-shaped convex portion 44 joined to the driving portion 17 of the multilayer piezoelectric element 14, and a thin film portion 4 formed around the convex portion 44.
5

The nozzle plate 35 has a large number of nozzles 34, which are fine holes for ejecting ink droplets. The diameter of the nozzles 34 is 35 μm or less at the ink droplet outlet side. I have. This nozzle plate 3
For example, Ni (nickel) metal plate 5 is manufactured by an electron forming method (electroforming), but Si or another metal material may be used. The quality of the nozzle plate 35 determines the shape of the ink droplet and the flight characteristics, and has a great influence on the image quality. In order to obtain higher-quality image quality, a surface uniformization process is indispensable. Water repellent layer 35a on ink ejection side
Is formed.

Further, ink supply holes 47, 48, and 49 for supplying ink supplied from the outside to the common liquid chamber 37 are formed in the substrate 13, the frame member 15, and the vibration plate 30, respectively. Ink is supplied via an ink supply pipe 50 connected to the ink supply hole 47.

In this ink jet, a drive waveform is applied to the drive section 17 via the common electrode pattern 24,
By applying a selection signal corresponding to the recorded image to the driving unit 17 via the individual electrode pattern 25, a displacement in the stacking direction occurs in the selected driving unit 17 and the corresponding pressurized liquid chamber 36 is moved to the diaphragm 30. Pressurized through the diaphragm 41 of
As a result, the ink in the pressurized liquid chamber 36 is pressurized and ejected from the nozzles 24 as ink droplets, so that an image can be recorded on paper.

In this ink jet head, after the drive unit 11 and the liquid chamber unit 12 are separately assembled in advance, the two units 11 and
12 are manufactured by adhesive bonding. That is, as shown in FIG. 5, an ink supply hole 47 and a groove 33 are formed in the substrate 13, and the electrode pattern 51 for the common electrode and the electrode patterns 52a and 52b for the individual electrodes are formed in advance including the groove 33.
Is formed by printing. These electrode patterns 51, 52a,
The material 52b is obtained by printing and sintering a printing material of an alloy such as Ni-Ag or Ag-Pt, but is not limited to this.

Next, as shown in FIG. 6, two plate-shaped independent piezoelectric elements 53a and 53b having electrodes to be end face electrodes 22 and 23 (see FIG. 3) formed on both end faces are mounted on a substrate using a positioning jig. The electrodes on the end faces of the piezoelectric elements 53a, 53b are connected to the electrode patterns 51, 52a, 52b of the substrate 13 and the conductive adhesives 26, 26 (see FIG. 3). Make an electrical connection.

Thereafter, using a dicer or a wire saw on which a diamond grindstone is set, for example, with a width of about 100 μm per pitch and a depth of about 5 μm from the surface of the substrate 13.
The cuts are made with 0 μm as a guide, and the piezoelectric elements 53a, 53b
To form the driving part 17 and the non-driving part 18 separately. At this time, a slit groove 54 (see FIG. 2) having a depth of about 50 μm is inserted into the substrate 13 and cut, so that the individual driving unit 17 and the non-driving unit 18 are completely independent, and the electrode patterns 51 and 52a, 52
b is also divided so that the electrode patterns 52a and 52b become individual independent individual electrodes 25. The groove 33 of the substrate 13
The slit groove 54 does not reach the electrode pattern 5
1 is connected to all the end face electrodes on the end face side facing each piezoelectric element 14 through the groove 33, and the common electrode 2
It becomes 4.

Thereafter, the frame member 15 is bonded and bonded to the substrate 13 on which the slit processing of the piezoelectric element has been completed to complete the drive unit 11, and the liquid chamber unit 12 separately processed and assembled to the drive unit 1 is bonded and bonded. I do.

A configuration relating to the electrical connection between the piezoelectric element and the driving IC (driver) in such an ink jet head will be described with reference to FIGS. FIG. 7 shows the surface of the substrate 13 (the surface to which the piezoelectric element is bonded).
FIG. 8 is a perspective view of the substrate 13 seen from the back side.

As shown in FIG. 8, a driver (drive IC) 60 for applying a drive waveform to the drive section 17 of each piezoelectric element 14 is mounted on the back side of the substrate 13. In addition, a through hole 61 for electrically connecting the channel electrode (individual electrode) 25 of the substrate 13 to the back surface side is formed. Plug 6 for electrical connection with
2 to provide a card edge type joint portion 65. Further, a connection pattern 63 for connecting the driver 60 to the through hole 61 of the individual electrode 25 and a connection pattern 64 for connecting the driver 60 and the plug contact 62 of the joint 65 are formed on the substrate 13.

As described above, the driver 60 is directly attached to the substrate 13.
By mounting the driver 60 and the piezoelectric element 14
In this case, the number of components and the ease of assembly can be reduced when the electrical connection is made, the configuration can be simplified, the cost can be reduced, and the reliability of the electrical connection section can be improved. The driver can be mounted on the surface of the substrate.

In this case, the cost can be further reduced by using a glass epoxy substrate as the substrate 13, and the strength can be ensured by using a ceramic substrate. Furthermore, the cost can be reduced by connecting the end of the substrate 13 as a card-edge type joint to an external connector for electrical connection.

It is to be noted that the electrical connection between the driver of the board 13 and the outside can be made by using an FPC cable 66 as shown in FIG. 9, thereby effectively utilizing a small space or the like. Can be.

[0036]

As described above, according to the ink-jet head of the first aspect, since the driver for driving the piezoelectric element is mounted on the substrate to which the piezoelectric element is bonded, the number of parts is reduced. Assembling work becomes easy,
The cost can be reduced and the reliability of the electrical connection of the head can be improved.

According to the ink jet head of the second aspect, since the substrate is a glass epoxy substrate in the ink jet head of the first aspect, the cost can be further reduced.

According to the ink jet head of the third aspect, in the ink jet head of the first aspect, the substrate is made of a ceramic substrate, so that sufficient substrate strength can be ensured.

According to a fourth aspect of the present invention, in the ink jet head of any one of the first to third aspects, the head is connected to the outside via a card edge type connecting portion provided on the substrate. Because
Further cost reduction can be achieved.

According to the ink jet head of the fifth aspect, in the ink jet head of any one of the first to third aspects, the head is configured to be connected to the outside via a flexible print cable, so that a small space or the like is required. It can be used effectively.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an example of an ink jet recording apparatus provided with an ink jet head to which the present invention is applied.

FIG. 2 is an exploded perspective view of the inkjet head.

FIG. 3 is an enlarged sectional view of a main part of the inkjet head.

FIG. 4 is an enlarged cross-sectional view of a main part of the inkjet head in a direction orthogonal to FIG.

FIG. 5 is a perspective view for explaining a process of assembling the drive unit.

FIG. 6 is a perspective view for explaining a process for assembling the drive unit.

FIG. 7 is a perspective view of a substrate showing a specific example of the present invention, as viewed from the front surface side.

FIG. 8 is a perspective view of the same substrate viewed from the back side.

FIG. 9 is a perspective view showing another example of the specific embodiment of the present invention.

FIG. 10 is a perspective view illustrating a conventional head unit.

FIG. 11 is a side view of the same.

FIG. 12 is an explanatory diagram illustrating a PCB of the head unit.

[Explanation of symbols]

4 carriage, 5 recording head, 11 drive unit, 12 liquid chamber unit, 13 substrate, 14 piezoelectric element, 15 frame member, 24 common electrode pattern, 2
5 Individual electrode pattern, 60 Driver, 61 Through hole, 62 Plug connection, 63, 64 Connection pattern, 65
... card edge type joint, 66 ... FPC cable.

Claims (5)

[Claims] 1. An ink jet head in which a piezoelectric element is bonded on a substrate and an ink droplet is ejected from a nozzle by displacement of the piezoelectric element, a driver for driving the piezoelectric element is mounted on the substrate. Inkjet head. 2. The ink jet head according to claim 1, wherein said substrate is a glass epoxy substrate. 3. The ink jet head according to claim 1, wherein said substrate is a ceramic substrate. 4. The ink-jet head according to claim 1, wherein said head is connected to the outside via a card-edge connection provided on said substrate. 5. The ink jet head according to claim 1, wherein the head is connected to the outside via a flexible print cable.