JP3444257B2 - Inkjet recording head - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head, and more particularly to an ink jet recording head that applies a voltage to a piezoelectric element to eject ink from a nozzle.

[0002]

2. Description of the Related Art Conventionally, various types of ink jet recording heads have been proposed. Among them, the piezoelectric type has been widely put into practical use. Problems in this piezoelectric ink jet recording head will be described.

FIG. 12 is a sectional view of a conventional ink jet recording head. In the ink jet recording head, the piezoelectric element 33 and the laminated flow path plate 36 are joined by an adhesive 39. 37 is a stress concentration portion, and 38 is a column break portion.

When the piezoelectric element and the laminated flow path plate are joined by a thermosetting adhesive as shown in FIG. 12, a problem with the thermosetting adhesive is that the linear expansion coefficient differs between both members. With the metal member forming the laminated flow channel plate and the piezoelectric element,
The laminated flow path plate was made of stainless steel at 11.8 × 10 ⁻⁶ , the nickel material was made at 13.4 × 10 ⁻⁶ , and the piezoelectric element was formed at 1.4 × 10 ⁻⁶ .
^-6 . Since pressure force is applied when the adhesive is heated and cured to obtain a close contact, the piezoelectric element is pulled by the laminated flow path plate with a large amount of deformation due to frictional force, and is formed by groove processing. Forced deformation in the shear direction occurs in the column of the piezoelectric element. Actually, as shown in FIG. 12, it is considered that an adhesive agent is present at the joint surface between the laminated flow channel plate and the piezoelectric element, so that the laminated flow channel plate and the piezoelectric element are not completely deformed together with the laminated flow channel plate. However, since the curing reaction of the adhesive has started, it cannot be considered that the adhesive deforms completely independently, and the state is considered to be in the intermediate state between integral deformation and independent deformation. As a result of this deformation, as shown in FIG. 12, the joint surface and the bottom of the pillar of the piezoelectric element are deformed, and the stress concentrates near the base of the pillar. The piezoelectric element is configured by laminating a piezoelectric material layer and an electrode layer, and has a weak laminated interface portion, so that the laminated interface near the stress concentrated portion is destroyed.

[0005]

As described above, in the conventional ink jet recording head of this kind, since the linear expansion coefficient of the laminated flow path plate and the piezoelectric element are greatly different, stress is generated near the base of the column of the piezoelectric element. There is a problem of being concentrated and destroyed.

An object of the present invention is to provide an ink jet recording head which prevents the pillar of the piezoelectric element from being destroyed.

[0007]

The ink jet recording head of the present invention is an ink jet recording head constituted by joining a piezoelectric element and a laminated flow path plate forming a pressure chamber, wherein the piezoelectric element is formed by groove processing. A driving column is formed, and the laminated flow path plate is formed by laminating plates in which punched holes are provided on an extension line in the groove processing pitch direction of the piezoelectric element.
It is characterized by being joined .

[0008]

[0009]

In the ink jet recording head of the present invention, the laminated flow path plate has a diaphragm having a diaphragm portion for pressurizing the pressure chamber, a chamber plate constituting the pressure chamber, and an ink pool which is a common ink reservoir. From a supply plate for supplying ink from the pressure chamber to the pressure chamber, an ink pool plate having the ink pool, a damper plate having a damper part for absorbing vibration, and a nozzle plate having nozzles for ejecting ink droplets are laminated and joined. It may be characterized by having done.

The ink jet recording head of the present invention may be characterized in that the plates of the laminated flow path plate are bonded by adhesion.

The ink jet recording head of the present invention may be characterized in that the piezoelectric element and the laminated flow path plate are bonded by adhesion.

The ink jet recording head of the present invention may further be characterized in that a nozzle plate cover is mounted on the nozzle plate side so as to close the hole.

[0014]

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a front view from the piezoelectric element side of an inkjet recording head according to a first embodiment of the present invention. FIG. 2 is a sectional view taken along the line AA of FIG. 1 showing the basic configuration of the inkjet recording head. 1 is an inkjet recording head, 2 is a hole for each plate, 3 is a piezoelectric element,
Reference numeral 4 is an ink supply port, 5 is an external individual electrode on the piezoelectric element 3, 6 is a laminated flow path plate forming a pressure chamber, 7 is a vibration plate, and 8
Is a chamber plate, 9 is a supply plate, 10 is an ink pool plate, 11 is a damper plate, 12 is a nozzle plate, and 13 is an external common electrode.

The piezoelectric element 3 constitutes a driving column corresponding to each nozzle of the nozzle plate 12 to be described later, and a laminated piezoelectric element grooved at a pitch at which dummy columns are formed at both ends of the driving column. There is. In addition, external electrodes (external individual electrode 5 and external common electrode 1) are provided on the back surface and the side surface of the piezoelectric element 3.
3) is printed and is soldered to a printed circuit board (not shown), and the piezoelectric element 3 is driven by transmitting an electric signal from the printed circuit board.

3 is a front view of the diaphragm 7, FIG. 4 is a front view of the chamber plate 8, FIG. 5 is a front view of the supply plate 9, FIG. 6 is a front view of the ink pool plate 10, and FIG. 7 is a damper plate 11. FIG. 8 is a front view of the nozzle plate 12. The configuration of the inkjet recording head 1 will be described in detail with reference to FIGS.

As a constitution of the laminated flow path plate 6 which supplies ink, pressurizes the ink filled in the pressure chamber described later, and performs ejection operation, an electric signal based on print data is transmitted to the piezoelectric element 3. As a result, when the piezoelectric element 3 is displaced,
A diaphragm 7 having a diaphragm portion 14 that pressurizes the pressure chamber in accordance therewith is provided. Furthermore, its upper surface (lower surface in FIG. 2)
In addition, a chamber plate 8 that constitutes a pressure chamber is provided, and an ink having a supply plate 9 that supplies ink from the ink pool 15 to each pressure chamber and an ink pool 15 that is a common ink pool are provided on the upper surface (lower surface in FIG. 2) of the chamber plate 8. A pool plate 10, a damper plate 11 having a damper portion 16 for absorbing vibration, and a nozzle plate 12 having a nozzle 17 for ejecting ink droplets on the uppermost surface (the lowermost surface in FIG. 2) are laminated and joined.

The vibrating plate 7 is made of stainless steel, nickel or the like, and a plate is formed by etching or electroforming to form the diaphragm portion 14. As another member, a resin such as polyimide and a metal member are attached to each other, and etching is performed so as to leave the metal member at the joint portion with the piezoelectric element 3. The chamber plate 8 is a metal plate obtained by etching a metal member such as stainless steel or nickel, or
An injection molded member made of a resin material, a member obtained by etching an inorganic material such as silicon or glass, or a photosensitive resin material such as a dry film is used. The supply plate 9 is etched using a metal member such as stainless steel or nickel. Similarly, the ink pool plate 10 and the damper plate 11 are also formed by etching using a metal member.

In the nozzle plate 12, it is necessary to process the nozzles 17 by a fine processing technique. As a method therefor, when a stainless material is used for a member, press working is used, and when a nickel material is used, an electroforming technique is used, and a polyimide is used. The nozzle 17 is formed in the resin material such as by laser processing using an excimer laser.

As a method for joining the plates, an adhesive is applied to each plate by a method such as screen printing.
Alternatively, a method in which a photosensitive resin such as a dry film used as a member for forming the chamber plate 8 is laminated on each plate, and the plates are laminated and pressure-heated and bonded.
Alternatively, a method of joining the chamber plate 8, the supply plate 9, and the ink pool plate 10 by thermal diffusion joining is used. When a resin plate is used for the nozzle plate 12, it is necessary to use a thermoplastic or thermosetting adhesive in advance.
A resin plate coated with μm to 10 μm can be used. Furthermore, when a resin plate is also used as the diaphragm, the same method can be used for bonding.

Among the holes 2 formed in each plate, the ink pool 15 is formed for the holes 2 on one side of the ink pool plate 10 and the damper plate 11 shown in FIGS. 6 and 7. , The shape is different from the other punched holes 2.

FIG. 9 is an enlarged sectional view of the piezoelectric element 3 and the vibrating plate 7 of the ink jet recording head 1 of FIG. As shown in FIG. 9, 18 is a pillar formed by grooving the piezoelectric element 3, 19 is an adhesive agent that joins the piezoelectric element 3 and the laminated flow path plate 6, and 20 is an adhesive piece that joins the vibration plate 7 and the chamber plate 8. The pressure chamber 21 is an internal electrode layer. The adhesive 19 is applied to the adhesive surface of the piezoelectric element 3 facing the diaphragm portion 14, and as the selected adhesive 19,
A two-component room temperature curing type adhesive or a thermosetting type epoxy adhesive is used, and the hardness after curing is as high as 80 to 95 (Shore A), and the diaphragm portion 14 moves when the driven piezoelectric element 3 moves.
And the displacement of the piezoelectric element 3 is preferably transmitted to the diaphragm portion 14 without loss, and the film thickness after curing is 3 μm to 5 μm. Adhesive 1
As the coating method of 9, a method such as screen printing, transfer, roller printing or the like is used.

Here, the two-component room temperature curing type adhesive described above is a mixed type having a short potting life, and therefore it is difficult to handle because of the need to control the compounding ratio and it is relatively used. It is a thermosetting adhesive. If the thermosetting adhesive is a one-component type, it does not need to control the compounding ratio and has a long potting life, so it is easy to handle. However, the problem with the thermosetting adhesive is that it is cured by applying heat during joining. A metal member that constitutes the laminated flow channel plate 6,
In the piezoelectric element 3, the laminated flow path plate 6 is made of stainless steel.
The linear expansion coefficient is 1.8 × 10 ⁻⁶ , the nickel material is 13.4 × 10 ⁻⁶ , and the piezoelectric element 3 is 1.4 × 10 ^−6, which is different from the linear expansion coefficient. Since pressure is applied when the adhesive 19 is pressed and heated and cured in order to obtain close contact, the piezoelectric element 3 is pulled by the laminated flow path plate 6 having a large amount of deformation due to a frictional force, and by the groove processing. The columns 18 of the formed piezoelectric element 3 are forcibly deformed in the shearing direction. Actually, as shown in FIG.
Although the adhesive 19 is present on the joint surface between the laminated flow channel plate 6 and the piezoelectric element 3, it is considered that the adhesive 19 is not completely deformed integrally with the laminated flow channel plate 6. Since the curing reaction has started, it is unlikely that they will deform completely independently, and it is considered that they are in an intermediate state between integral deformation and independent deformation. By this transformation,
Deformation occurs at the joint surface and bottom of the pillar of the piezoelectric element 3
May be destroyed.

In the first embodiment shown in FIG. 1, the vibrating plate 7, the chamber plate 8, and the vibrating plate 7, which constitute the laminated flow path plate 6,
Each of the supply plate 9, the ink pool plate 10, the damper plate 11, and the nozzle plate 12 has a hole 2 formed on an extension line of the piezoelectric element 3 in the groove processing pitch direction. The punched holes 2 serve to reduce the amount of thermal deformation of the laminated flow channel plate 6 due to linear expansion that occurs when the laminated flow channel plate 6 and the piezoelectric element 3 are bonded with a thermosetting adhesive, whereby the piezoelectric element 3 is formed. It is possible to reduce the shearing force applied to the pillar 18 and prevent the piezoelectric element 3 from being broken.

FIG. 10 is a perspective view of the ink jet recording head 1 of FIG. 1 joined to a head case. Reference numeral 22 is a head case, and 23 is a nozzle plate cover. An ink cartridge (not shown) is attached to the head case 22, and ink is filled in the ink supply port 4 of the inkjet recording head 1 via the head case 22. The inkjet recording head 1 and the head case 22 are joined by an adhesive, and the application range of the adhesive at this time is that the head case 22 is applied outside the punched hole 2.
Is joined with. Further, a nozzle plate cover 23 is attached to the nozzle plate 12 side in a shape that closes the punched holes 2 at both ends. This prevents the ink from adhering to the piezoelectric element 3 through the drain hole 2 and being short-circuited by wiping the ink during the wiping operation.

Next, a second embodiment of the present invention will be described. FIG. 11 is a sectional view of the second embodiment (a sectional view taken along the line AA in FIG. 1). Referring to FIG. 11, a slit 24 is provided on the surface of the piezoelectric element 3 opposite to the grooved surface. By processing the slits 24, when the laminated flow channel plate 6 and the piezoelectric element 3 are joined, the piezoelectric element 3 is shaped to follow the thermal deformation of the laminated flow channel plate 6, and the pillars 18 of the piezoelectric element 3 are formed. It has the effect of reducing the shearing force applied to.

In the second embodiment of the present invention shown in FIG. 11, at least one slit 24 is machined on the surface opposite to the groove machined surface of the piezoelectric element 3, but the number of slits 24 is not limited. .

[0029]

As described above, according to the present invention, since holes are formed in each of the plates constituting the laminated flow channel plate, the holes can thermoset the laminated flow channel plate and the piezoelectric element. The adhesive serves to reduce the amount of thermal deformation of the laminated flow path plate due to the linear expansion that occurs at the time of joining, thereby reducing the shearing force applied to the columns of the piezoelectric element and preventing the piezoelectric element from being destroyed.

Further, since the nozzle plate cover is mounted on the nozzle plate side so as to close the holes at both ends, the ink adheres to the piezoelectric element through the holes when the ink is wiped off during the wiping operation. It has the effect of preventing short circuit.

Further, as in the second embodiment, providing a slit on the surface opposite to the grooved surface of the piezoelectric element also has the effect of reducing the shearing force applied to the column of the piezoelectric element.

[Brief description of drawings]

FIG. 1 is a front view from the piezoelectric element side of an inkjet recording head according to a first embodiment.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a front view of a diaphragm.

FIG. 4 is a front view of a chamber plate.

FIG. 5 is a front view of a supply plate.

FIG. 6 is a front view of an ink pool plate.

FIG. 7 is a front view of a damper plate.

FIG. 8 is a front view of a nozzle plate.

9 is a sectional view taken along line BB of FIG.

FIG. 10 is a perspective view in which an inkjet recording head is joined to a head case.

FIG. 11 is a cross-sectional view taken along the line AA of FIG. 1 in the second embodiment.

FIG. 12 is a cross-sectional view of a conventional inkjet recording head.

[Explanation of symbols]

1 Inkjet recording head 2 punch holes 3 Piezoelectric element 4 Ink supply port 5 External individual electrode 6 laminated flow board 7 diaphragm 8 chamber plates 9 Supply plate 10 ink pool plate 11 damper plate 12 nozzle plate 13 External common electrode 14 Diaphragm part 15 ink pool 18 pillars 19 adhesive 20 pressure chamber 21 Internal electrode layer 22 head case 23 Nozzle plate cover

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41J 2/045 B41J 2/055 B41J 2/16

Claims (5)

(57) [Claims] 1. An ink jet recording head configured by joining a piezoelectric element and a laminated flow channel plate forming a nozzle and a pressure chamber, wherein the piezoelectric element has a drive column formed by groove processing, and the laminated flow channel is formed. The plate is each plate in which a punched hole is provided on an extension line in the groove processing pitch direction of the piezoelectric element.
An ink jet recording head comprising a plurality of laminated and joined layers . 2. The laminated flow path plate includes a diaphragm having a diaphragm portion that pressurizes the pressure chamber, a chamber plate that forms the pressure chamber, and an ink pool that is a common ink reservoir, and ink is transferred from the ink pool to the pressure chamber. And a nozzle plate having a nozzle portion for ejecting ink droplets are laminated and joined. The inkjet recording head according to claim 1. 3. The ink jet recording head according to claim 2, wherein the plates of the laminated flow path plate are bonded by adhesion. 4. The ink jet recording head according to claim 1, 2 or 3, wherein the piezoelectric element and the laminated flow path plate are bonded by adhesion. 5. Before SL nozzle plate side, claim 2, 3 or 4 ink jet recording head wherein a wearing the nozzle plate cover in a shape closing the drain hole.