JP2000108346A - Ink jet recording head and piezoelectric oscillator unit suitable therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bond a piezoelectric oscillator and a flexible cable through an anisotropic conductive film while ensuring sufficient reliability by flowing a polymer material into a recess made at the joint of a flexible cable and solidifying the polymer material thereby bonding the flexible cable and the piezoelectric oscillator. SOLUTION: An anisotropic conductive film 40 is mounted on the segment electrode 24 of an oscillator unit and the joint 34 of a flexible cable 13 is located. When a specified pressure is applied from the surface of the cable 13 while heating by means of a heater tool 41 and then the heater tool 41 is removed upon elapsing a specified time, conductive particles are concentrated with high density at a part where the electrode 24 faces the flexible cable 13 except the region of a hole 35 at the joint 34 and conductivity is exhibited. In the region of the hole 35 at the joint 34, polymer material flowing into the hole 35 is solidified to bond the cable 13 and the piezoelectric oscillator 9 rigidly and to bond the piezoelectric oscillators 9 integrally in a nonoscillatory region thus enhancing mechanical strength.

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 for recording images and characters on recording paper by discharging ink droplets from nozzle openings by expansion and contraction of a piezoelectric vibrator in a longitudinal vibration mode. The present invention relates to a connection structure between a vibrator unit configured by fixing a piezoelectric vibrator at a fixed pitch on a fixed substrate and a flexible cable for supplying a drive signal to the vibrator unit.

[0002]

2. Description of the Related Art Among ink jet recording heads,
A print head using a piezoelectric vibrator in the vertical vibration mode that can be driven at high speed has a nozzle opening and a part of the pressure generating chamber communicating with the reservoir formed with an ink ejection part by an elastic plate, and expands and contracts in the axial direction. The piezoelectric vibrator to be driven is driven by a vibrator unit having one end fixed to a fixed substrate at a constant pitch.

In such a vibrator unit, the rear end of the piezoelectric vibrator is connected to a connection pattern of a flexible cable by soldering so as to receive a drive signal from the outside.

[0004]

The piezoelectric vibrator is:
Since the length is at most several millimeters and the width is about 0.05 mm, which is extremely small, and the gap between them is small, there is a problem that a short circuit occurs due to melting of solder. In order to solve such a problem, a paste prepared by kneading conductive particles into a heat-sealable polymer material, which is widely used for joining work between a semiconductor element and a printed circuit board, and shaping the paste into a film shape. It is also conceivable to use an anisotropic conductive member such as an anisotropic conductive film. However, since the anisotropic conductive film has a lower bonding force than solder, it is not possible to secure sufficient strength for bonding with a piezoelectric vibrator accompanied by mechanical displacement. There is a problem that reliability is reduced.
The present invention has been made in view of such a problem, and an object of the present invention is to provide an inkjet recording method in which a piezoelectric vibrator and a flexible cable are joined by an anisotropic conductive film while securing sufficient reliability. Is to provide a head.

[0005]

According to the present invention, there is provided a pressure generating device which is connected to a reservoir through a nozzle opening and an ink supply port and is pressurized by a driving piezoelectric vibrator. In an ink jet recording head comprising a plurality of chambers and supplying a driving signal to the piezoelectric vibrator through a flexible cable, the piezoelectric vibrator is fixed to a fixed substrate, and the flexible cable is formed on a base material by a conductive layer forming material. Are laminated to form a conductive pattern, and a connection portion corresponding to an arrangement pitch of the pressure generating chambers is formed by exposing the conductive layer forming material at a tip of the conductive pattern, and the connection portion and the piezoelectric vibrator are formed. The flexible cable is conductively connected to the connection region through an anisotropic conductive film, and the anisotropic conductive material that has flowed into a recess near the connection portion. Is joined to the piezoelectric vibrator by the polymer bonding agent constituting the.

[0006]

[Function] At the connection between the piezoelectric vibrator and the flexible cable, conductive particles are present at a high density to generate conductivity, and the polymer material flows into the recess and solidifies, and the flexible cable and the piezoelectric vibrator are connected to each other. Is firmly joined.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a first embodiment of the present invention. FIGS. 1 and 2 show an embodiment of an ink jet recording head according to the present invention. A passage unit 1 communicates with a nozzle plate 3 in which nozzle openings 2 are formed at a constant pitch and a nozzle opening 2. A pressure generating chamber 4, a flow path forming substrate 7 having a reservoir 6 for supplying ink to the pressure generating chamber 4 through an ink supply port 5, and a pressure generating chamber 4 in contact with the tip of each piezoelectric vibrator 9 of the vibrator unit 8. An elastic plate 10 for expanding and reducing the volume of the chamber 4 is integrally laminated.

The flow path unit 1 is provided on an opening surface 12 of a holder 11 formed by injection molding of a polymer material or the like. The vibrator unit 8 is provided with a flexible cable 13 for transmitting a drive signal from the outside. After being connected with the conductive film 40 interposed therebetween, the frame 15 is housed in the housing chamber 14, the contact surfaces with the respective holders 11 are fixed with an adhesive, and the frame 15 which also serves as an electrostatic shielding material is provided on the nozzle plate side. Into the recording head.

FIG. 3 shows an embodiment of the vibrator unit 8 according to the present invention, in which an electrode serving as one pole and an electrode serving as the other pole are laminated in a sandwich shape via a piezoelectric material. The other end of the formed piezoelectric material plate is fixed to a fixed substrate 20 so that one end is a free end, and wire saws or the like are equally spaced so as to leave dummy vibrators 21 and 22 slightly wider at both ends. Thus, the piezoelectric vibrators 9, 9, 9 are mechanically cut into comb teeth at regular intervals so as to form a continuous portion at the rear end serving as a fixed region.

Each piezoelectric vibrator 9 is provided at the free end of the piezoelectric vibrator 9.
A segment electrode 24 as an external electrode connected to one of the internal electrodes, and a common electrode as an external electrode connected to the flexible cable 13 while being connected to the other internal electrode of each piezoelectric vibrator 9 on the fixed substrate side. 25 are formed. The common electrode 25 includes conductive layers 27 and 28 formed on the dummy piezoelectric vibrators 21 and 22 via the continuous region.
It is connected to the.

As shown in FIGS. 4A and 4B, the flexible cable 13 for supplying a drive signal to the vibrator unit 8 includes a base material 30 made of a heat-resistant electrical insulating film such as polyimide and a surface of the base material 30. And a conductive layer 31 formed by attaching a copper foil or the like to the piezoelectric vibrator 9.
Conductive pattern 3 suitable for supplying signals to 9, 9 °
2, 32, 32,... Are etched.

The conductive layer 31 has a conductive pattern 3 connected to a print signal output means such as a host at the other end.
3, 33, 33,... Are formed in a similar manner.

The conductive patterns 32, 32, 32,.
On the tip side of ‥, the connecting portions 3 are arranged at pitches corresponding to the segment electrodes 24, 24, ‥‥ of the piezoelectric vibrators 9, 9, 9 ‥‥.
4, 34, 34 ‥‥ are formed, and holes 35, 35, 35, ‥‥, or recesses formed by half-etching to the extent that the conductivity of the connection portions 34, 34, 34 維持 is maintained as shown in FIG. Are formed.

The whole of the conductive pattern 32 and the area other than the connection portion 36 of the conductive pattern 33 are covered with a flexible cover coat 37 having electrical insulation as required.

Reference numeral 38 in the figure denotes a semiconductor integrated circuit that generates a signal for selecting and driving the piezoelectric vibrators 9, 9, 9,... Based on a print signal supplied from the outside. Further, reference numeral 39 in the figure denotes a dummy piezoelectric vibrator 2.
Connection portions connected to the first and second conductive layers 27 and 28 are connected to the ground of an external drive circuit by the conductive layer 40.

Next, the connection between the flexible cable 13 and the piezoelectric vibrator unit will be described. Fig. 6 (a)
The anisotropic conductive film 40 is mounted on the segment electrodes 24, 24, 24 # of the vibrator unit 8 fixed to the jig with the segment electrodes 24, 24, 24 # facing upward as shown in FIG. Connection part 3 of the flexible cable 13
4, 34, 34 ° are positioned.

Next, as shown in FIG. 6 (b), when a constant pressure is applied from the surface of the flexible cable 13 while heating with the heater tool 41, the anisotropic conductive film becomes segment electrodes 24, 24, High pressure is applied in the region of 24 °.

The polymer material constituting the anisotropic conductive film 40 is softened, and the holes 35 of the connection portions 34 of the segment electrodes 24 are softened.
Excluded from other areas, conductive particles (black dots in the figure)
Remains and develops conductivity only in the thickness direction.

On the other hand, connecting portions 34, 34, 34 # of the segment electrodes 24, 24, 24 and the flexible cable 13
In the region opposing the holes 35, 35, and 35, the polymer material flows into the hole 35 because the pressure on the anisotropic conductive film 40 is low, so that the polymer material is not so much removed in this region.

When the heater tool 41 is removed after a lapse of a predetermined time, the holes 3 in the connection portions 34, 34, 34 # of the segment electrodes 24, 24, 24 and the flexible cable 13 are removed.
Conductive particles (black dots in the figure) exist at a high density in a portion where the region other than region 5 is opposed to generate conductivity.

On the other hand, in the area of the holes 35, 35, 35 of the connecting portions 34, 34, 34 # of the flexible cable 13, the polymer material which has flowed into the hole 35 and solidified connects the flexible cable 13 and the piezoelectric vibrator. The piezoelectric vibrators 9 are firmly joined to such a degree that they are not peeled off by displacement, and the piezoelectric vibrators are integrally joined in a non-vibration region to increase the mechanical strength.

Thus, the flexible cable 13
When a drive signal is applied to each of the piezoelectric vibrators 9 of the piezoelectric vibrator unit 8 connected to the piezoelectric vibrator unit 10, the piezoelectric vibrator 9 contracts and expands to displace the elastic plate 10. As a result, the volume of the pressure generation chamber 4 expands and contracts, and the ink in the reservoir 6 flows into the pressure generation chamber 4 via the ink supply port 5, and the ink in the pressure generation chamber 4 is pressurized and flows through the nozzle opening 2. Ink droplets are ejected.

In the above-described embodiment, the recess near the piezoelectric vibrator is formed by the hole 35 provided in the connecting portions 34, 34, 34,..., But as shown in FIG. The portions 34, 34, 34 are formed in a triangular zigzag pattern, in an arabesque pattern as shown in FIG. 8, or as part of an arabesque pattern as shown in FIG. A similar effect can be obtained even if is formed as a curved surface.

In the above embodiment, the connecting portion 3
4, 34, 34,..., A concave portion for polymer inflow is formed, but as shown in FIG. Project
A gap G about the thickness of the conductive layer 31 may be formed between the piezoelectric vibrator 9 and the piezoelectric vibrator 9.

According to this embodiment, since the pressure by the heater tool 41 is low in a region where the conductive layer 31 does not exist,
Since the polymer material of the anisotropic conductive film 40 shown in FIG. 10B sufficiently remains, bonding with high strength is possible.

In the above embodiment, the anisotropic conductive member formed into a film is used. However, an anisotropic conductive paste obtained by kneading conductive particles into a heat-welding polymer material is used. It is clear that the same action is exerted even if the agent is applied in a layered manner to the joining region and adhered by the same method.

[0027]

As described above, according to the present invention, the piezoelectric vibrator is fixed to the fixed substrate, and the flexible cable is formed by laminating a conductive layer forming material on a base material to form a conductive pattern. A connection portion corresponding to the arrangement pitch of the pressure generating chambers is formed by exposing the conductive layer forming material at the end of the pattern, and a flexible cable is provided between the connection portion and the connection region of the piezoelectric vibrator via an anisotropic conductive member. Is electrically conductively connected to the piezoelectric vibrator by the polymer bonding agent constituting the anisotropic conductive member flowing into the recess near the connection portion, so that the connection between the piezoelectric vibrator and the connection portion of the flexible cable is performed. In the region, conductive connection can be made by the presence of conductive particles at high density, and the flexible cable and piezoelectric vibrator are made of a polymer material that has flowed into the recess near the piezoelectric vibrator and solidified. It can be joined to a solid.

[Brief description of the drawings]

FIG. 1 is an assembled perspective view showing one embodiment of an ink jet recording head of the present invention.

FIG. 2 is a diagram showing a cross-sectional structure of the recording head.

FIG. 3 is a perspective view showing one embodiment of a unit used for the recording head.

FIGS. 4A and 4B are plan views showing an embodiment of a flexible cable of a recording head according to the embodiment, and FIGS.
It is sectional drawing in the -A line.

FIGS. 5A and 5B are a top view and a cross-sectional view, respectively, showing the connection region of the flexible cable in the same manner as above, in an enlarged manner.

FIGS. 6 (a) and 6 (b) are views showing a joining process of the flexible cable and the piezoelectric vibrator unit, respectively.

FIG. 7 is a top view showing another embodiment of the flexible cable in which a connection region is enlarged.

FIG. 8 is a top view showing another embodiment of the flexible cable in which a connection region is enlarged.

FIG. 9 is a top view showing another embodiment of the flexible cable in which a connection region is enlarged.

FIGS. 10A and 10B are diagrams showing another embodiment of the present invention, respectively, in a joining step of a flexible cable and a piezoelectric vibrator unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flow-path unit 8 Vibrator unit 9 Piezoelectric vibrator 13 Flexible cable 24 Segment electrode 25 Common electrode 30 Base material 31 Conductive layer 32 Conductive pattern 34 Connection part 35 hole 41 Anisotropic conductive film

Claims (26)

[Claims] A plurality of pressure generating chambers that communicate with a reservoir via a nozzle opening and an ink supply port and are pressurized by a driving piezoelectric vibrator, wherein a driving signal is supplied to the piezoelectric vibrator via a flexible cable. In the ink jet recording head to be supplied, the piezoelectric vibrator is fixed to a fixed substrate, and the flexible cable is formed by laminating a conductive layer forming material on a base material to form a conductive pattern, and the tip of the conductive pattern is A connection portion corresponding to the arrangement pitch of the pressure generating chambers is formed by exposing the conductive layer forming material, and the flexible cable is connected between the connection portion and a connection region of the piezoelectric vibrator via an anisotropic conductive member. Are conductively connected to each other, and are bonded to the piezoelectric vibrator by a polymer bonding agent constituting the anisotropic conductive member flowing into the recess near the connection portion. An ink jet recording head. 2. The ink jet recording head according to claim 1, wherein the anisotropic conductive member is made of a film material or a paste. 3. The ink jet recording head according to claim 1, wherein a connection portion of the flexible cable and a connection region of the piezoelectric vibrator are conductively connected by conductive particles constituting the anisotropic conductive member. . 4. The ink jet recording head according to claim 1, wherein a connection region between the piezoelectric vibrator and the flexible cable is a surface of the piezoelectric vibrator facing the fixed substrate. 5. The ink jet recording head according to claim 1, wherein the recess is formed by a hole formed in the connection portion. 6. The ink jet recording head according to claim 5, wherein the holes are formed by half-etching the conductive pattern. 7. The ink jet recording head according to claim 1, wherein the recess has a zigzag shape at the connection portion. 8. The ink jet recording head according to claim 1, wherein the concave portion is formed by projecting the base member toward the distal end side from the connection portion. 9. The ink jet recording head according to claim 1, wherein a plurality of the piezoelectric vibrators are fixed at a fixed pitch, and a non-vibration region is fixed to the fixed substrate. 10. The ink jet type recording head according to claim 1, wherein said piezoelectric vibrator is formed by mechanically separating a piezoelectric material plate at a predetermined interval into a comb-like shape. 11. An external electrode which has a conductive relationship with an internal electrode of the piezoelectric vibrator and is exposed on a surface of the piezoelectric vibrator in a connection region of the piezoelectric vibrator. Inkjet recording head. 12. The ink jet recording head according to claim 1, wherein the flexible cable interconnects the piezoelectric vibrators in a non-vibration region of the piezoelectric vibrator. 13. The piezoelectric vibrator according to claim 1, wherein the piezoelectric vibrator is formed by laminating a plurality of piezoelectric materials and conductive materials.
3. The ink jet recording head according to item 1. 14. A piezoelectric vibrator unit in which a piezoelectric vibrator is fixed to a fixed substrate and receives a drive signal from a flexible cable, wherein the piezoelectric vibrator is fixed to the fixed substrate, and the flexible cable is fixed to a base material. While forming a conductive pattern by laminating a conductive layer forming material, a connection portion corresponding to an arrangement pitch of the pressure generating chambers is formed by exposing the conductive layer forming material at a tip of the conductive pattern, and the connection portion is formed. The flexible cable is conductively connected to a connection region of the piezoelectric vibrator via an anisotropic conductive member, and a polymer junction forming the anisotropic conductive member flowing into a recess near the connection portion A piezoelectric vibrator unit joined to the piezoelectric vibrator by an agent. 15. The piezoelectric vibrator unit according to claim 14, wherein the anisotropic conductive member is made of a film material or a paste. 16. The connection portion of the flexible cable and the connection region of the piezoelectric vibrator are conductively connected by conductive particles constituting the anisotropic conductive member.
5. The piezoelectric vibrator unit according to 4. 17. The piezoelectric vibrator unit according to claim 14, wherein a connection region between the piezoelectric vibrator and the flexible cable is a surface of the piezoelectric vibrator facing the fixed substrate. 18. The piezoelectric vibrator unit according to claim 14, wherein the recess is formed by a hole formed in the connection portion. 19. The piezoelectric vibrator unit according to claim 18, wherein the holes are formed by half-etching the conductive pattern. 20. The piezoelectric vibrator unit according to claim 14, wherein the recess forms the connection portion in a zigzag shape. 21. The piezoelectric vibrator unit according to claim 14, wherein the concave portion is formed by projecting the base member toward the distal end side from the connection portion. 22. The piezoelectric vibrator unit according to claim 14, wherein a plurality of said piezoelectric vibrators are fixed at a fixed pitch, and a non-vibration region is fixed to said fixed substrate. 23. The piezoelectric vibrator unit according to claim 14, wherein the piezoelectric vibrator is formed in a comb shape by mechanically dividing a piezoelectric material plate at regular intervals. 24. The external electrode which has a conductive relationship with an internal electrode of the piezoelectric vibrator and is exposed on a surface of the piezoelectric vibrator in a connection region of the piezoelectric vibrator. Piezoelectric vibrator unit. 25. The piezoelectric vibrator unit according to claim 14, wherein the flexible cable interconnects the piezoelectric vibrators in a non-vibration region of the piezoelectric vibrator. 26. The piezoelectric vibrator according to claim 1, wherein a plurality of piezoelectric materials and conductive materials are laminated.
5. The piezoelectric vibrator unit according to 4.