JP2000263781A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance reliability while reducing the size and cost by providing a pattern connecting with a printed board in a region other than a region where means for connecting a pressure generating means with a plane other than that provided with the pressure generating means is formed. SOLUTION: Discrete end face terminal on the side of end face not facing each piezoelectric element in each array of piezoelectric elements is connected with discrete lead-out electrode on a substrate 3 through a conduction processing material. Each discrete lead-out electrode and a common electrode are conducted with a connection pattern, i.e., a rear surface discrete electrode pattern 33 and a rear surface common electrode pattern 35, through through-hole electrodes 23, 25, respectively. A printed board, i.e., an FPC, is connected at a connection region (connecting part, contact part) with a flexible print cable FPC and applied with a drive voltage. Consequently, a field is generated in the laminating direction and an elongation is induced in the piezoelectric element in the laminating direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly to a connection structure between an ink jet head and a printed circuit board.

[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 uses a piezoelectric element (piezo type), a heating resistor (bubble type), an actuator means (pressure generating means) such as a diaphragm and a counter electrode (electrostatic type) to record a signal. And prints an image on a recording medium by ejecting and flying ink droplets from the nozzles.

For example, as an ink jet head using a piezoelectric element, as described in Japanese Patent Application Laid-Open No. 8-142324, a plurality of stacked piezoelectric elements are joined on a head substrate and arranged in a plurality of rows. At the same time, a frame member located around the piezoelectric element is joined, a diaphragm having a diaphragm is laminated on the piezoelectric element and the frame member, and a diaphragm is formed on the diaphragm by a laminated piezoelectric element. A pressurized liquid chamber that is pressurized through the liquid chamber and a liquid chamber partition member that forms an ink supply path that supplies ink to the liquid chamber are stacked, and a nozzle plate having a nozzle formed on the liquid chamber partition member is further stacked. In addition, there is an example in which an ink droplet is ejected from a nozzle by a displacement of a laminated piezoelectric element in a d33 direction.

In an ink jet head using such a piezoelectric element, it is necessary to electrically connect the piezoelectric element to a printed circuit board on which a driver (drive IC) for applying a required driving waveform to the piezoelectric element is mounted. Conventionally, a wire bonding method has been used (Japanese Unexamined Patent Publication No.
-320721).

However, in the case of the wire bonding method, it is necessary to select an electrode material for the head-side substrate and the printed-board-side electrode, for example, to use gold plating. In addition, in the case of a highly integrated nozzle (for example, 100 nozzles or more) for sequentially connecting one by one, the number of wire bondings increases, the work time is long, and the cost is high. Furthermore, the wire bonding portion has many problems, such as a need to seal the wire bonding portion to protect it from disconnection due to contact between wires, impact, or the intrusion of foreign matter.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 6-320721, there is a method in which the electrodes of the piezoelectric element and the flexible printed cable (FPC) are directly connected by solder or anisotropic conductive tape.

As a method of connecting a flexible wiring board, as disclosed in Japanese Utility Model Application Laid-Open No. 5-28673, a plate-like piezoelectric body having electrodes disposed therearound is sandwiched between a lower substrate and an upper substrate. A method is known in which a plurality of through-hole electrodes are formed around each of a substrate and a plate-shaped piezoelectric body, and a drive electrode and a flexible substrate are connected through the through-holes.

[0008]

However, in the above-described structure in which the piezoelectric element and the FPC are directly connected, the FP
Since the connection portion with C (also referred to as a contact portion or a contact region) is in the same direction as the nozzle on the substrate surface, it is necessary to provide thorough protection to prevent ink from adhering and leaking between the electrodes. No. Also, since the contact portion with the FPC does not have a flow path plate, a common liquid chamber plate, and a nozzle plate and needs to have an exposed surface, it is necessary to extend an extra piezoelectric element at least longer than the length of the contact portion. Thus, the size of the piezoelectric body increases.

In a structure using a through-hole, since connection to a flexible substrate can be made on the substrate surface opposite to the piezoelectric body, thorough protection for preventing contamination by ink and the like and a large piezoelectric body are required. Although there is no need to perform this process, the substrate becomes considerably uneven in order to form a through-hole. Therefore, it is unknown as to the connection with the flexible substrate with high reliability and high yield as long as it is disclosed in the above publication.

The present invention has been made in view of the above points, and has as its object to provide an ink jet recording apparatus capable of realizing high density, small size, low cost, and high reliability of a mounted ink jet head. I do.

[0011]

In order to solve the above-mentioned problems, an ink jet recording apparatus according to the first aspect of the present invention changes a nozzle for discharging ink droplets, a liquid chamber communicating with the nozzle, and a volume of the liquid chamber. Ink jet having a pressure generating means for generating pressure and an ink jet head having the pressure generating means provided on a substrate, and a printed circuit board on which a pattern for applying a drive waveform to the pressure generating means of the ink jet head is formed. In the recording apparatus, the substrate is provided with connecting means for connecting the surface other than the surface on which the pressure generating means is provided and the pressure generating means, and further connected to the printed board in an area other than the area where the connecting means is formed. The connection pattern is provided. The “printed board” is used to include a printed board (PCB), a flexible printed cable (FPC), a conductive film, and the like.

According to a second aspect of the present invention, in the inkjet recording apparatus of the first aspect, the connecting means is connected to a surface other than the surface on which the pressure generating means is provided through a through hole formed in the substrate. The connection means was connected to a generating means, and the connection pattern was provided on the back surface of the substrate.

According to a third aspect of the present invention, there is provided the ink jet recording apparatus according to the first or second aspect, wherein
At least a part of a region excluding a region for connecting the pattern of the printed circuit board is covered with an insulating material.

According to a fourth aspect of the present invention, in the ink jet recording apparatus of any one of the first to third aspects, the maximum arrangement pitch of the connection patterns is equal to or greater than the arrangement pitch of the connection means.

According to a fifth aspect of the present invention, there is provided an ink jet recording apparatus according to any one of the first to fourth aspects, wherein the connecting means are arranged in a plurality of rows.

According to a sixth aspect of the present invention, there is provided the ink jet recording apparatus according to any one of the first to fifth aspects, wherein a plurality of connecting portions of the connection pattern with the printed circuit board are arranged.

According to a seventh aspect of the present invention, in the ink jet recording apparatus of the first aspect, the pressure generating means is arranged in two or more rows, and two or more rows of connecting means corresponding to each of the pressure generating means are provided. The connection part with the substrate was provided inside the connection means.

An ink jet recording apparatus according to an eighth aspect of the present invention is the ink jet recording apparatus according to any one of the first to seventh aspects, wherein connection portions of the connection pattern to the printed circuit board are arranged on both sides of the connection means. did.

According to a ninth aspect of the present invention, in the ink jet recording apparatus of any one of the first to eighth aspects, the connection pattern and the printed circuit board are connected by an anisotropic conductive material.

[0020] The ink jet recording apparatus of claim 10 is
The inkjet recording apparatus according to any one of claims 1 to 9, further comprising a plurality of inkjet heads, wherein at least two or more
It is configured to be provided on one printed circuit board.

[0021]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an external perspective view showing an example of an ink jet head section of the ink jet recording apparatus according to the first embodiment of the present invention, FIG. 2 is an exploded perspective view of the ink jet head, and FIG. 3 is along the line AA in FIG. FIG. 4 is an enlarged cross-sectional view of a main part along line BB in FIG. 1, FIG. 5 is an enlarged cross-sectional view of a main part of FIG. 3, and FIG. 6 is a rear view of the substrate.

This ink jet head comprises an actuator unit 1 and a liquid chamber unit 2 joined on the actuator unit 1. The actuator unit 1 includes two piezoelectric element rows 4 and 4 in which a plurality of laminated piezoelectric elements are arranged (arranged) in a row on an insulating substrate 3.
Further, a frame member 5 surrounding the periphery of these two piezoelectric element rows 4 is joined by an adhesive 6. The piezoelectric element array 4 is composed of a plurality of piezoelectric elements 7 to which a driving pulse for making ink droplets fly.

The liquid chamber unit 2 is made of a photosensitive resin film (dry film resist) or a metal plate such as SUS forming a pressurized liquid chamber, a common ink flow path, etc. on a diaphragm 12 having a diaphragm 11 formed thereon. The flow path partition member 13 is bonded by thermocompression bonding of a dry film resist or an adhesive, and a nozzle plate 15 having a plurality of nozzles 14 formed on the flow path partition member 13 is bonded.

A plurality of substantially independent pressurized liquid chambers 16 each having a diaphragm portion 11 facing the piezoelectric element 7 of each piezoelectric element row 4 by the vibration plate 12, the flow path partition member 13 and the nozzle plate 15, The common liquid chamber 17 arranged on both sides of the pressurized liquid chamber 16 and the common liquid chamber 17
Fluid resistance portion 1 serving as an ink supply path for supplying ink to ink 6
Nozzles 14 are formed, and the nozzles 14 communicating with the pressurized liquid chamber 16 are arranged to face each piezoelectric element 7. The diaphragm 12 of the liquid chamber unit 2 is joined to the actuator unit 1 with high rigidity by an adhesive.

The substrate 3 of the actuator unit 1 has a thickness of about 0.5 to 5 mm and is made of a material similar to a piezoelectric element, and can be cut together with the piezoelectric element by, for example, a diamond grindstone. Preferably,
It is preferable that through holes can be formed at a high density corresponding to the piezoelectric elements 7.

Each end of the substrate 3 in the direction perpendicular to the direction in which the piezoelectric elements 7 are arranged is divided by slit grooves 21 connecting the end faces of the individual piezoelectric elements 7 of each piezoelectric element row 4 that do not face each other. Individual extraction electrodes 22 for giving a selection signal to the piezoelectric element 7 are formed, and each individual extraction electrode 22 is connected to the back surface of the substrate 3 via a through-hole electrode 23 as connection means. Further, a common electrode 24 for giving a drive waveform to each piezoelectric element is formed between the piezoelectric element rows 4 and 4, and the common electrode 24 is a through-hole electrode
5 is connected to the back side of the substrate 3.

Here, the positional relationship between the piezoelectric element 7 and the individual extraction electrodes 22 and the common electrode 24 is slightly spaced, as shown in FIG. This is because the piezoelectric element 7 is
This is because if the electrodes 22 and 24 are placed on the piezoelectric elements 2 and 24, the thickness and the error of the electrodes 22 and 24 affect the joining quality of the piezoelectric element 7, that is, the uniformity of the joining and the plane parallel accuracy after the joining. However, as long as the piezoelectric element 7 slightly overlaps the individual extraction electrode 22 and the common electrode 24, there is little adverse effect.

As shown in FIGS. 3 and 5, the piezoelectric element 4 is composed of a laminated piezoelectric element having ten or more layers and has a thickness of 20.
~50μm / 1 layer of PZT (= Pb (Zr · Ti ) O 3) 2
6 and silver / paradium (AgPd) with a thickness of several μm / 1 layer
And the internal electrodes 27 made of aluminum.
Then, an electrode corresponding to the internal electrode 26 is not formed on the upper surface of the uppermost layer 26a of the piezoelectric element 7 so as to be an inactive layer. The material used for the piezoelectric element is not limited to the above, and Ba, which is generally used as a piezoelectric element material, may be used.
A ferroelectric material such as TiO ₃ , PbTiO ₃ , and (NaK) NbO ₃ can also be used.

Then, a large number of internal electrodes 27 of the piezoelectric elements 7 of each piezoelectric element row 4 are alternately taken out on both end faces alternately and connected to individual end face electrodes 28 and 29 made of, for example, AgPd formed on both end faces. And each piezoelectric element 7 in each piezoelectric element row 4
Are connected to the common electrode 24 on the substrate 3 via a conduction processing material 30 having a Young's modulus of 200 kgf / mm ² or more, so that the piezoelectric elements 7 in each piezoelectric element row 4 do not face each other. The individual end face electrode 29 on the end face side is connected to the individual extraction electrode 22 on the substrate 3 via the conduction processing material 31.

Each of the individual extraction electrodes 22 and the common electrode 24
As shown in FIG. 6, through-hole electrodes 23, 2 are respectively provided.
5 is a back side individual electrode pattern 3 which is a connection pattern via
3 and the back surface common electrode pattern 35, and the FPC 37 which is a printed circuit board is connected in the connection region (connection portion, contact portion) with each FPC 37 (see FIG. 1).
When the driving voltage is applied, an electric field is generated in the stacking direction, and a displacement in the piezoelectric element 7 is caused to expand in the stacking direction (displacement in the direction d33 in the same direction as the electric field).

The frame member 5 has a green expansion coefficient of 2 × 10
^A plate-shaped member made of an epoxy resin thermosetting molding material having a temperature of ^-6 / ° C. or less,
8 and 39 are drilled to form fixing portions 40 and 41 on one side in a direction orthogonal to the direction in which the piezoelectric elements 7 are arranged. A fixing portion 42 is formed, and bridging portions 43 are formed at both ends of the fixing portions 40 to 42 in the direction in which the piezoelectric elements 7 are arranged. In addition, an ink supply hole 5 a corresponding to the ink supply hole 3 a of the substrate 3 is formed in one bridge portion 43 of the frame member 5.

The fixing portion 42 of the frame member 5
As shown in FIG. 3, a conductive paste (conductive bonding agent) 44 is applied to the entire lower surface, and the common electrode 2 divided for each piezoelectric element 7 (each channel) by the slit groove 21.
4 are connected to each other to form an integral common electrode 24.

Next, as shown in FIG. 3, the diaphragm 12 of the liquid chamber unit 2 has a flat surface on the side of the pressurized liquid chamber 16 and a diaphragm region 12 having a different thickness on the side of the piezoelectric element row 4.
a, a bonding region 12b is formed, and a diaphragm portion 11 is formed corresponding to the piezoelectric element 7 of the piezoelectric element row 4. The diaphragm 12 is made of a Ni (nickel) metal plate, and is manufactured by an electroforming method. Note that the diaphragm 12 also has an ink supply hole 12d.

The flow path partition member 13 is located between the upper surface of the vibration plate 12 and the nozzle plate 15 to form a flow path of the pressurized liquid chamber 16 and the like. It comprises a member 51 and an upper channel partition member 52.

The lower flow path partition member 51 is made of a photosensitive resin film or a SUS substrate adhered to the upper surface of the vibration plate 12, and as shown in FIG. Independent flow paths such as a pressurized liquid chamber 16 are formed corresponding to each of the piezoelectric elements 7, and each pressurized liquid chamber 1 is formed.
The pressurized liquid chamber 16 includes a large number of inner partition walls 53 forming a fluid resistance portion 18 also serving as an ink supply path, and an outer peripheral partition wall 54 forming a common liquid chamber 17 around the pressurized liquid chamber 16. The upper flow path partition member 52 has substantially the same configuration as the lower flow path partition member 51, except that there is no portion corresponding to the fluid resistance portion 18 of the lower flow path partition member 51.

The nozzle plate 15 is provided with a number of nozzles 14 which are fine holes for ejecting ink droplets. The diameter of the nozzles 14 is 5 at the ink droplet outlet side.
The nozzle 14 is formed at a position corresponding to the vicinity of the center of the pressurized liquid chamber 16. The nozzle plate 15 is also made of a Ni metal plate like the diaphragm 12, and is manufactured by an electroforming method.

In this embodiment, an example has been described in which the common liquid chamber 17 is provided on both sides of the pressurized liquid chamber 16 and ink is supplied from both sides. However, the common liquid chamber and the fluid resistance section are provided only on one side. A configuration in which ink is supplied from one side may be used. The position of the nozzle is not particularly limited to the center, and may be provided near the end of the pressurized liquid chamber.

Next, the manufacturing process of the ink jet head will be described. This ink jet head is manufactured by separately assembling the actuator unit 1 and the liquid chamber unit 2 in advance, and then bonding the two units 1 and 2 together. By adopting such a manufacturing process, it is possible to select and assemble non-defective products of both units 1 and 2 to improve the yield, and to reduce the possibility that dust and the like are likely to be generated in the processing and assembling process. Can be assembled in a separate step with the liquid chamber unit 2 where it is desired to completely avoid the adhesion of the ink jet head, etc., so that the quality itself of the completed inkjet head is improved.

Hereinafter, a specific description will be given. First, the processing and assembling steps of the actuator unit 1 are as follows. That is, as shown in FIG.
An ink supply hole 3a is formed in advance on a substrate 3 made of an electrically insulating material such as a highly rigid resin. Further, through holes 23a and 25a are formed in a part of a position to be an individual extraction electrode and a part of a position to form a common electrode.

Then, an individual extraction electrode pattern 61 made of a conductive material for forming the individual extraction electrodes 22 is formed on both sides of the substrate 3, and bypasses the center of the substrate 3 and the individual extraction electrode pattern 61. Electrode pattern 6 made of a conductive material so as to face both ends of the substrate 3
2 is formed, and a portion between the individual extraction electrode pattern 61 and the common electrode pattern 62 is defined as a piezoelectric element bonding region 63. Further, simultaneously with or after forming the individual extraction electrode pattern 61 and the common electrode pattern 62,
A layer made of a conductive material may be formed on the inner walls of the through holes 23a and 25a.

As shown in FIG. 6, on the back surface of the substrate 3, the back surface individual electrode pattern 33 extends from the through-hole electrode 23 of the individual lead electrode 22 to the connection with the FPC 37.
From the through-hole electrode 25 of the common electrode 25 to the FPC3
The back surface common electrode pattern 35 is formed up to the connection portion with No. 7. After that, the through holes 23a and 25a are filled with a material having good conductivity such as Ag, and the through hole electrodes 23 and 25a are filled.
5 is formed. Filling method is to make Ag into paste,
Injection into the through holes 23a, 25a, drying and solidification can be easily performed.

Further, at least the FP of the back surface individual electrode pattern 33 on the back surface of the substrate 3 and the back surface common electrode pattern 35
It is preferable that a portion other than a connection portion with C37 is covered with an insulating material such as a photosensitive resin and easy to form a pattern. This is to prevent the electrodes from coming into contact with each other due to the protrusion or scattering of the solder at the time of connection of the FPC 37, and to perform more reliable FPC mounting.

For example, as the coating pattern with the photosensitive resin 69, as shown in FIG. 8, the entire area other than the area excluding the connection areas 33a and 35a with the FPC 37 may be covered.
As shown in FIG. 9, connection areas 33a, 3
The portion other than the portion 5a may be covered, or only the portion between the adjacent FPC connection regions 33a and 35a may be covered as shown in FIG.

The FPC of the individual back electrode pattern 33 and the common electrode pattern 35 as connection patterns
The connection regions 33a and 35a are formed inside the substrate 3 from the positions of the through holes 23a and 25a as shown in FIG. Thus, the size of the head can be reduced without increasing the size of the substrate 3 for forming the connection portion with the FPC 37.

Each of these electrodes (electrode patterns) 22, 2
4, 33, and 35 are, for example, metal deposition of Ni, Au, Cu, or the like, or electrolysis, electroless plating, or Ag of the same metal.
It is formed by a method such as printing of a thick film conductor paste such as Pd, AgPt, or Au paste, and is adhered to the surface of the substrate 3.

Then, as shown in FIG. 11, a piezoelectric element plate 64 in which a laminated piezoelectric element is formed in a plate shape (or sheet shape) in the piezoelectric element bonding region 63 on the substrate 3.
Are bonded together using an adhesive (see FIG. 3). The adhesive used for bonding the piezoelectric element plate 64 to the substrate 3 is preferably one having a Young's modulus of 200 kgf / mm ² or more, and a heat-curable epoxy adhesive is used here.
As the form of the adhesive, one-pack type, two-pack type,
Any of a film type and the like can be used.

The individual end face electrodes (individual external electrodes) 2 are previously provided on the short side end faces of these piezoelectric element plates 64.
After the end face electrodes for forming the electrodes 8 and 29 are formed and bonded to the substrate 3 by bonding, the end face electrodes on the opposite sides of the two piezoelectric element plates 64 are connected to the common electrode pattern on the substrate 3. 62 and electrically connected to the individual lead electrode patterns 61 on the substrate 3 with the conduction processing material 31. I do. As the conduction processing materials 30 and 31, those having a Young's modulus of 200 kgf / mm ² or more are used. Further, as the conduction treatment material, for example, a conductive adhesive, sputtering of Au or the like, vapor deposition of Au or the like, dipping of AgPd or the like can be used.

Next, the surface portions of the two piezoelectric element plates 64 and the substrate 3 are set at a predetermined pitch in a direction orthogonal to the end face electrodes, for example, with a width of about 100 μm per pitch by a dicer or the like in which a diamond grindstone is set. A plurality of laminated piezoelectric elements 7 are divided and formed at the same time by performing slit processing for cutting at a pitch at which the piezoelectric elements 7 are formed. At the same time, the end electrodes are divided into individual end electrodes 28 and 29 corresponding to the individual piezoelectric elements 7. .

At this time, as shown in FIG. 5, by cutting the substrate 3 to a predetermined depth and cutting it by inserting the slit grooves 21, the individual piezoelectric elements 7 can be completely independent and the individual extraction electrodes can be formed. The pattern 61 is connected to each piezoelectric element 7
Are individually divided into individual extraction electrodes 22 respectively corresponding to the respective electrodes. In this case, a part of the common electrode pattern 62 on the substrate 3 is also divided corresponding to each piezoelectric element 7.

It should be noted that the separately formed individual extraction electrodes 22
Remain connected to the individual end face electrodes 29 on the end faces of the individual piezoelectric elements 7 that do not face each other via the conductive material 31. Further, the common electrode pattern 62 is still connected to the individual end face electrode 28 on the end face side of the piezoelectric element row 4 facing the piezoelectric element 7 via the conductive material 30.

As described above, the lead-out electrode pattern 61 is formed on the insulating substrate 3, and the internal electrodes 27 are alternately taken out in advance on both end faces and are electrically connected to the end face electrodes formed on each end face. After bonding the elements 64 and connecting the extraction electrode pattern 61 and the end face electrodes of the multilayer piezoelectric element 64 by conducting the connection processing, the slit processing is simultaneously performed on the surface of the multilayer piezoelectric element 64 and the surface of the substrate 3. Is formed, and the extraction electrode pattern 61 and the end face electrode are individually divided into the individual extraction electrodes 28 and the individual end face electrodes 29 which individually correspond to the plurality of piezoelectric elements 7, respectively. The high-density integration can be achieved, the electrode can be easily taken out from the internal electrode 27, and the bonding strength between the piezoelectric element and the substrate is high, so that the piezoelectric element during slit processing can be used. By reducing damage of the child, and yield is improved, it is possible to reduce the cost.

By using materials having a Young's modulus of 200 kgf / mm ² or more as the conduction treatment materials 30 and 31 for conducting the end face electrodes of the laminated piezoelectric element and the extraction electrodes on the substrate, the vibration between the piezoelectric element and the substrate can be improved. Can be reduced, and breakage of the laminated piezoelectric element during slit processing can be further reduced. Further, by using an adhesive having a Young's modulus of 200 kgf / mm ² or more as an adhesive between the substrate 3 and the piezoelectric element 7, vibration between the laminated piezoelectric element and the substrate can be reduced, and the piezoelectric element during slit processing can be reduced. Breakage can be reduced, and the efficiency of the head can be improved by preventing a decrease in displacement efficiency when the piezoelectric element 7 is driven.

In this manner, the frame member 5 is bonded onto the substrate 3 on which slit processing such as the piezoelectric element plate 64 has been completed, using an adhesive made of a thermosetting epoxy adhesive having a Young's modulus of 200 kgf / mm ² or more. Join. At this time, by applying a conductive paste 44 to the back surface of the fixing portion 42 of the frame member 5, the common electrode forming patterns 62 divided by slitting are connected to each other,
The common electrode 24 is formed.

Here, it is necessary that the upper surface of the frame member 5 and the upper surface of the piezoelectric element 7 after the bonding of the frame member 5 are accurately and coplanar. This is because the diaphragm 12 of the liquid chamber unit 2 is joined to this portion as described later, and if the surface accuracy is poor, the diaphragm portion 11 that is not bonded is generated.

Therefore, the surface processing can be performed as an inactive layer without forming an electrode on the upper surface of the uppermost layer 26a of the piezoelectric element 7, and the frame member 5 slightly higher than the height of the piezoelectric element 7 can be formed.
After bonding, the surface of the piezoelectric element 7 is ground.
Grinding is performed until the upper surface is slightly ground and becomes the same plane, thereby eliminating the dimensional accuracy of both parts and the difficulty of the bonding method.

Then, on the actuator unit 1 completed in this way, the liquid chamber unit 2 separately processed and assembled is placed with its diaphragm 12 side (joining surface) downward.
Adhesively bond while aligning.

Thereafter, as shown in FIG. 12, the back surface individual electrode pattern 33 and the back surface common electrode pattern 35 on the back surface of the substrate 3 are partially connected to the connection regions 33a, 3b except for the through holes.
As 5a, the electrode pattern 37a of the FPC 37 is joined by heat and pressure. Note that the FPC 37 has a pattern that can selectively drive the piezoelectric elements 7 of the piezoelectric element row 4, and the joints thereof are plated with solder in advance. In this case, FPC
The temperature at the time of thermocompression bonding of 37 is required to be higher than the melting temperature of the solder, and is usually 200 ° C. or higher.

Here, the through-hole electrodes 23 and 25 are
For example, a material with good electrical conductivity such as a metal wire can be made by arranging it in ceramics in advance and firing it. However, this method is difficult to process and achieves the desired arrangement with high precision. Is difficult.

Therefore, a method of making a hole in the substrate 3 with a drill or the like is used. This is achieved by forming through holes (through holes) 23a and 25a in the substrate 3 with a drill and forming a material having good electrical conductivity such as metal on the inner wall of the through hole, or filling the material with the material. . This method is excellent in that a through hole of a desired size can be formed at a desired position with relatively high accuracy, and the cost is low.

However, in this method, a lot of burrs are generated around the through-hole, so that the through-hole portion becomes significantly uneven on the substrate, and when the solder is thermocompression-bonded at this portion, poor contact is likely to occur. . Therefore, in the present invention,
By forming an electrode pattern from the through hole and avoiding the through hole and performing thermocompression bonding on a relatively flat substrate portion, a highly reliable FPC mounting becomes possible.

As an electrical connection method between the FPC and the back surface individual electrode pattern and the back surface common electrode pattern, an anisotropic conductive film can be used instead of solder.
The anisotropic conductive film is a thermosetting or thermoplastic resin film in which conductive particles (metal particles and carbon particles) called fillers are dispersed, and the back surface individual electrode pattern and the individual common electrode pattern By heating and pressing the anisotropic conductive film between the FPCs, the back surface individual electrode pattern and the back surface common electrode pattern and the electrodes of the FPC are conducted through the filler. Even in the case of an anisotropic conductive film, the reliability is similarly improved by thermocompression bonding at a flat portion other than the through hole.

Further, the solder connection method fixes the substrate 3 and the FPC only by the solder of the electrode portion, whereas the anisotropic conductive film forms the electrode portion as well as the electrode portion. Even in the non-existing portion, the resin of the anisotropic conductive film serves as an adhesive to fix the substrate and the FPC, so that it is more preferable to obtain an adhesive strength. Further, since thermocompression bonding can be performed at 150 ° C. or less, generation of stress caused by thermal expansion or contraction of the resin substrate of the FPC by heating and pressing the FPC is reduced, and there is no peeling of the electrode. preferable.

After mounting the FPC in this manner, finally, the ink supply pipe 4 is inserted into the ink supply hole 3a of the substrate 3.
8 is inserted, an adhesive is applied, cured, and fixed.

Here, since the frame member 5 of the actuator unit 1 is formed of an epoxy resin-based thermosetting molding material having a linear expansion coefficient of 2 × 100 ⁻⁶ / ° C. or less,
When the diaphragm 12 of the liquid chamber unit 2 is bonded to the frame member 5 by bonding, the diaphragm 12 is not deformed even by heat bonding. Thus, the frame member 5 and the liquid chamber unit 2
Can be bonded by heating, improving the assemblability,
Costs are also reduced.

As described above, the substrate 3 and the frame member 5, the actuator unit 1 and the liquid chamber unit 2,
The cost is reduced by using the same epoxy-based heat-curable adhesive having a Young's modulus of 200 kgf / mm ² or more as the adhesive for bonding the piezoelectric element 7 and the substrate 3.

Next, the operation of the ink jet head configured as described above will be described. The pulse voltage is applied by selectively applying a drive pulse voltage of 20 to 50 V to the piezoelectric element 7 in accordance with a recording signal. The moved piezoelectric element 7 is displaced and the corresponding diaphragm portion 1 of the diaphragm 12 is moved.
1 is deformed in the direction of the nozzle 14, the ink in the pressurized liquid chamber 16 is pressurized by the change in the volume (volume) of the pressurized liquid chamber 16, and the ink is ejected from the nozzle 14 of the nozzle plate 15 as droplets, Records can be made.

Then, the ink pressure in the pressurized liquid chamber 16 decreases as the ink droplets are ejected, and a slight negative pressure is generated in the pressurized liquid chamber 16 due to the inertia of the ink flow at this time. In this state, by turning off the application of the voltage to the piezoelectric element 7, the diaphragm portion 11 of the diaphragm 12 returns to the original position and the pressurized liquid chamber 16 returns to the original shape. Negative pressure is generated. At this time, ink that has entered from an ink supply pipe 48 that leads to an ink tank (not shown) passes through the common liquid chamber 27 and is filled into the pressurized liquid chamber 16 from the fluid resistance unit 28. Then, after the vibration of the ink meniscus surface of the nozzle 14 is attenuated and stabilized, a pulse voltage is applied to the piezoelectric element 7 for discharging the next ink droplet.

In the above embodiment, the individual end electrodes 28 and 29 on both end surfaces of the piezoelectric element 7 and the common electrode 24,
A conduction treatment material 30 for conducting treatment with the individual extraction electrodes 22;
31 is attached to a part of the outer surface of the individual end face electrodes 28 and 29, but the conduction processing materials 30 and 31 are attached to the individual end face electrodes 2 and 29.
By performing a conduction process by adhering to the entire surface of each of the piezoelectric elements 8 and 29, the bonding strength between the piezoelectric element plate 64 and the substrate 3 before slitting with respect to the piezoelectric element plate 64 before the piezoelectric element 7 is dramatically improved. This can further reduce damage to the laminated piezoelectric element during slit processing.

Further, in the above embodiment, an example was described in which the opening direction of the nozzle was coaxial with the displacement direction of the piezoelectric element, and the invention was applied to a side shooter type ink jet head. The present invention can also be applied to an edge shooter type ink jet head which is set in a direction perpendicular to the direction. Further, in this embodiment, the FPC is used as the printed circuit board, but the same effect can be obtained by using a rigid board having no flexibility (a so-called PCB board). However, in the case of the rigid board, the connection is made on the piezoelectric element side. Then, since the thickness of the substrate is large, there is a problem that the substrate is higher than the nozzle surface, so that the present invention is further effective.

Next, a second embodiment of the present invention will be described with reference to FIG.
3 will be described. This figure is an explanatory view of the back side of the substrate. With the head of the first embodiment described above, 100 dp
In the case where the density is increased to i or more, when thermocompression bonding is performed using, for example, solder, solder protrudes from the edge of the electrode, and may come into contact with an adjacent electrode to conduct electricity.

That is, the nozzle array density of one row is 100
In the case of dpi or more, the arrangement pitch of the nozzles is 254 μm, and the through-holes correspond to it, so that the arrangement pitch of the through-holes is also 254 μm. For example, when the back surface individual electrode pattern 33 is formed with line / space = 127 μm / 127 μm, the interval between the electrodes is only 127 μm, whereas the amount of solder is about 80 μm at the maximum and 160 μm for both electrodes. To some extent, adjacent electrodes may come into contact with each other.

Therefore, in the present embodiment, the back surface individual electrode pattern 33 has the individual electrode through-hole 23a as the narrowest part and has a wide area, and the front end is provided with a contact area 33a with the FPC 37.

Therefore, the pitch d1 of the back surface individual electrode pattern in the contact region 33a is larger than the pitch d2 of the individual electrode through hole 23a (d1> d).
2). As a result, even if solder protrudes, the adjacent electrodes do not come into contact with each other, and a reliable FP
C mounting becomes possible.

Next, a different example of the third embodiment of the present invention will be described with reference to FIGS. Both figures are explanatory diagrams on the back surface side of the substrate. In the head according to the first embodiment described above, when the density is increased to 100 dpi or more, if the through holes are formed in one row, there is a limit in reducing the diameter of the through holes, and the wall between the through holes is small. When a through hole is formed, cracks may occur in the wall portion, or in the worst case, the wall may be lost and the through holes may be connected.

Therefore, in this embodiment, the through holes 23a for the back surface individual electrode pattern are formed in a staggered arrangement. As a result, it is possible to secure a sufficient distance between the through-holes, so that a large wall thickness can be ensured, and the occurrence of cracks and communication between the through-holes can be prevented. The performance is improved.

Here, the contact area 33a with the FPC 37
May be formed in one row as shown in FIG. 14, or may be arranged in a zigzag like the through holes as shown in FIG.

When the contact areas are formed in one line, the contact areas can be collectively thermocompression-bonded to the FPC.
The width of the heating / pressing head of the crimping device for heating and pressing can be reduced, and the temperature unevenness of the heating / pressing head is reduced, so that highly reliable connection with little variation can be performed in all contact areas. it can. Further, since the pressing area is reduced, the pressing force of the crimping device for obtaining the pressure required for thermocompression bonding can be reduced, and the thermocompression bonding device itself can be reduced in size and cost.

On the other hand, when the contact areas are arranged in a staggered pattern similar to the through holes, the lengths of the individual back electrode patterns between the through holes and the contact areas can be made substantially the same. The wiring resistance of the electrode pattern can be made substantially the same, the driving voltage waveform of the piezoelectric element does not vary due to the wiring resistance, ink droplets can be ejected without variation, and the image quality is improved.

Next, a fourth embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. This figure is also an explanatory view of the back side of the substrate. With the head of the first embodiment described above, 100 dp
In the case where the density is increased to i or more, when thermocompression bonding is performed using, for example, solder, solder protrudes from the edge of the electrode, and may come into contact with an adjacent electrode to conduct electricity.

That is, the nozzle array density of one row is 100
In the case of dpi or more, the arrangement pitch of the nozzles is 254 μm, and the through-holes correspond to it, so that the arrangement pitch of the through-holes is also 254 μm. For example, when the back surface individual electrode pattern 33 is formed with line / space = 127 μm / 127 μm, the interval between the electrodes is only 127 μm, whereas the amount of solder is about 80 μm at the maximum and 160 μm for both electrodes. To some extent, adjacent electrodes may come into contact with each other.

Therefore, in the present embodiment, the back surface individual electrode patterns 33 are alternately made to have different lengths,
The contact areas 33a with the 37 are arranged in a staggered manner. Therefore, it is possible to secure a sufficient distance between the contact regions 33a. As a result, even if the hang protrudes, there is no contact with the adjacent electrode, and a reliable FPC
Implementation becomes possible.

In this case, as shown in the figure, the back surface individual electrode pattern 33 adjacent to the adjacent contact region 33a is covered with an insulating resist 69, so that a high-density such that there is only a space less than the protruding amount of the hang. (300
(dpi or more), contact between the electrodes does not occur.

Next, a fifth embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. This figure is also an explanatory view of the back side of the substrate. As described above, in the head according to the first embodiment, when the density is increased to 100 dpi or more, when thermocompression bonding is performed using, for example, solder, solder protrudes from the edge of the electrode, and contacts the adjacent electrode. Conduction may occur.

That is, the nozzle array density of one row is 100
In the case of dpi or more, the arrangement pitch of the nozzles is 254 μm, and the through-holes correspond to it, so that the arrangement pitch of the through-holes is also 254 μm. For example, when the back surface individual electrode pattern 33 is formed with line / space = 127 μm / 127 μm, the interval between the electrodes is only 127 μm, whereas the amount of solder is about 80 μm at the maximum and 160 μm for both electrodes. To some extent, adjacent electrodes may come into contact with each other.

On the other hand, if the amount of solder for connection is small (the thickness of the solder layer is small), sufficient connection is not performed, and poor contact is likely to occur. On the other hand, if the amount of solder is too large (the thickness of the solder layer is large), the solder will largely protrude from the electrode portion due to pressure during thermocompression bonding. Therefore, although there is an optimum value for the thickness of the solder, in order to connect with high reliability, the amount of solder protruding is about 80 μm at the maximum and about 160 μm on both side electrodes as described above. Contact may occur.

Therefore, in the present embodiment, the extraction direction of the back surface individual electrode pattern 33 is changed every other through hole. Therefore, it is possible to secure a sufficient distance between the contact regions 33a. This allows
Even if the hang protrudes, it does not come into contact with the adjacent electrode, and a highly reliable FPC can be mounted.

In this case, as shown in FIG.
By covering the portions other than 3a and 35a with the insulating resist 69, even in the case of high density (300 dpi or more) where there is only a space less than the amount of solder protruding,
Contact between the electrodes does not occur.

Next, a sixth embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. When an ink jet recording apparatus (including an image forming apparatus) such as a printer is speeded up or colored, for example, printing is performed by using a plurality of heads of black ink, yellow (Y), magenta (M), cyan (C). ), Black (K) four colors, or light magenta, cyan plus six colors, and red (R), green (G), and blue (B) plus seven colors. Become.

In this embodiment, the two heads 81
Are mounted on one FPC 82. Each head 81
As described above, the through hole is formed and the rear surface is connected to the FPC 82. In this way, F
FPC connection becomes easy by connecting with PC,
Further, since the width of the head may be as small as necessary, downsizing in the case of a multi-head can be realized. Of course 2
Not only one head but also three or more heads can be formed on the same FPC.

In each of the embodiments described above, the present invention is applied to a piezo-type ink-jet head using a piezoelectric element as an actuator. However, the present invention is also applied to a bubble-type ink-jet head using a heating resistor. Alternatively, the present invention can be applied to an electrostatic ink jet head using electrostatic force between a diaphragm and an electrode facing the diaphragm.

[0091]

As described above, according to the ink jet recording apparatus of the first aspect, the substrate on which the pressure generating means of the ink jet head is provided has a surface other than the surface on which the pressure generating means is provided and the pressure generating means. A connection means for connecting is provided, and a connection pattern for connecting to the printed circuit board is provided in an area other than the area where the connection means is formed, so that the reliability is improved, the extraction electrode portion is shortened, and the size is reduced. Cost reduction can be achieved.

According to the ink jet recording apparatus of claim 2, in the ink jet recording apparatus of claim 1,
The connection means is configured to connect the surface other than the surface on which the pressure generating means is provided and the pressure generating means via a through hole formed in the substrate, and to provide a connection pattern on the back surface of the substrate, thereby improving reliability. In addition, the length of the extraction electrode is shortened, so that downsizing and cost reduction can be achieved.

According to the ink jet recording apparatus of the third aspect, in the ink jet recording apparatus of the first or second aspect, at least a part of a region excluding a region for connecting a pattern of a printed board is coated with a material having an insulating property. With this configuration, it is possible to prevent short-circuiting between electrodes when mounting the printed circuit board, thereby improving reliability, and improving yield and cost reduction.

According to the ink jet recording apparatus of the fourth aspect, in the ink jet recording apparatus of any one of the first to third aspects, the maximum arrangement pitch of the connection patterns is equal to or larger than the arrangement pitch of the connection means. A short circuit between electrodes can be prevented during mounting on a substrate, reliability can be improved, and miniaturization can be achieved.

According to the fifth aspect of the present invention, in the ink jet recording apparatus according to any one of the first to fourth aspects, the connecting means is arranged in a plurality of rows, so that reliable mounting can be performed. And the density can be increased.

According to the ink jet recording apparatus of the sixth aspect, in the ink jet recording apparatus of any one of the first to fifth aspects, the connection portions of the printed circuit board of the connection pattern are arranged in a plurality of rows. Mounting can be performed, and high density can be achieved.

According to the ink jet recording apparatus of claim 7, in the ink jet recording apparatus of claim 1,
At least two rows of pressure generating means are arranged, and two
Since the connection means of the rows or more is provided and the connection portion with the printed circuit board is provided inside the connection means, the head can be miniaturized.

According to the ink jet recording apparatus of the eighth aspect, in the ink jet recording apparatus of any one of the first to seventh aspects, the connection portion between the connection pattern and the printed board is arranged on both sides of the connection means. Because
Reliable mounting can be performed, and high density can be achieved.

According to the ink jet recording apparatus of the ninth aspect, in the ink jet recording apparatus of any one of the first to eighth aspects, the connection pattern and the printed board are connected by an anisotropic conductive material. Can be achieved.

According to a tenth aspect of the present invention, in the ink jet recording apparatus according to any one of the first to ninth aspects, a plurality of ink jet heads are mounted, and at least two of the ink jet heads are on a single printed circuit board. With the configuration provided above, the size of the multi-head can be reduced.

[Brief description of the drawings]

FIG. 1 is an external perspective view illustrating an example of an inkjet head unit of an inkjet recording apparatus according to a first embodiment of the present invention.

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

FIG. 3 is an enlarged sectional view of a main part along the line AA in FIG. 1;

FIG. 4 is an enlarged sectional view of a main part along the line BB in FIG. 1;

FIG. 5 is an enlarged view of a main part of FIG. 3;

FIG. 6 is an explanatory view of the back surface of the substrate of the head.

FIG. 7 is a perspective explanatory view for explaining a manufacturing process of the actuator unit of the head.

FIG. 8 is an explanatory view showing another first example of the back surface of the substrate of the head.

FIG. 9 is an explanatory view showing another second example of the back surface of the substrate of the head.

FIG. 10 is an explanatory view showing another third example of the back surface of the substrate of the head.

FIG. 11 is an explanatory perspective view for explaining a manufacturing process of the actuator unit of the head.

FIG. 12 is an explanatory perspective view for explaining a manufacturing process of the actuator unit of the head.

FIG. 13 is a back surface explanatory view of a substrate used for describing a second embodiment of the present invention;

FIG. 14 is a back surface explanatory view of a substrate used for describing a third embodiment of the present invention;

FIG. 15 is a back surface explanatory view of a substrate used for describing another example of the embodiment;

FIG. 16 is a back surface explanatory view of a substrate used for describing a fourth embodiment of the present invention;

FIG. 17 is a back surface explanatory view of a substrate used for describing a fifth embodiment of the present invention;

FIG. 18 is a back surface explanatory view of a substrate used for describing another example of the embodiment.

FIG. 19 is a perspective explanatory view for explaining a sixth embodiment of the present invention;

[Explanation of symbols]

1. Actuator unit, 2. Liquid chamber unit, 3.
Substrate, 4 ... piezoelectric element row, 5 ... frame member, 7 ... piezoelectric element, 12 ... diaphragm, 13 ... flow path partition member, 14 ... nozzle, 15 ... nozzle plate, 22 ... individual extraction electrode, 23
... through-hole electrodes, 24 ... common electrodes, 25 ... through-hole electrodes, 33 ... back surface individual electrode patterns, 35 ... back surface common electrode patterns, 37 ... FPC.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ryo Aoki 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2C057 AF35 AF65 AF93 AG15 AG16 AG82 AG92 AG93 AP02 AP14 AP22 AP25 AP47 BA04 BA14

Claims (10)

[Claims] A nozzle for discharging ink droplets, a liquid chamber communicating with the nozzle, pressure generating means for generating a pressure for changing the volume of the liquid chamber, and an ink jet head provided with the pressure generating means on a substrate. In an ink jet recording apparatus having a printed circuit board mounted thereon and having a pattern for applying a drive waveform to the pressure generating means of the ink jet head, the substrate has a surface other than the surface on which the pressure generating means is provided, and An ink jet recording apparatus, comprising: connecting means for connecting to pressure generating means; and a connecting pattern for connecting to the printed circuit board in a region other than a region where the connecting means is formed. 2. The ink jet recording apparatus according to claim 1, wherein the connection unit connects a surface other than the surface on which the pressure generation unit is provided and the pressure generation unit via a through hole formed in the substrate. An ink jet recording apparatus, wherein the connection pattern is provided on a back surface of the substrate. 3. The ink jet recording apparatus according to claim 1, wherein at least a part of a region except a region for connecting a pattern of the printed circuit board is coated with a material having an insulating property. apparatus. 4. The ink jet recording apparatus according to claim 1, wherein a maximum arrangement pitch of the connection patterns is equal to or larger than an arrangement pitch of the connection means. 5. The ink jet recording apparatus according to claim 1, wherein said connecting means are arranged in a plurality of rows. 6. The ink jet recording apparatus according to claim 1, wherein a plurality of connecting portions of the connection pattern with the printed board are arranged. 7. The ink jet recording apparatus according to claim 1, wherein the pressure generating means is arranged in two or more rows, and two or more rows of connecting means corresponding to each of the pressure generating means are provided. An ink jet recording apparatus provided inside the connection means. 8. An ink jet recording apparatus according to claim 1, wherein connection portions of said connection pattern to a printed circuit board are arranged on both sides of said connection means. . 9. The ink jet recording apparatus according to claim 1, wherein the connection pattern and the printed board are connected by an anisotropic conductive material. 10. The ink jet recording apparatus according to claim 1, wherein a plurality of ink jet heads are mounted, and at least two or more of the ink jet heads are provided on one printed circuit board. Characteristic inkjet recording device.