JP2000108348A - Ink jet recording head and imaging apparatus employing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cross talk caused by residual vibration of a piezoelectric oscillator after ejecting an ink drop. SOLUTION: The ink jet recording head comprises a piezoelectric oscillator unit 15 including a plurality of piezoelectric oscillators 9 operating in longitudinal oscillation mode secured to a fixed substrate 13 through an adhesive layer 14, and a channel unit 1 for ejecting an ink drop upon receiving a displacement of the piezoelectric oscillator 9 being secured by a head holder 16 wherein the thickness t of the adhesive layer 14 is managed to absorb the eigen period oscillation of the piezoelectric oscillator 9 by means of a spacer material.

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 structure for fixing a vibrator and a fixed substrate that integrates the vibrator into a unit.

[0002]

2. Description of the Related Art A part of a pressure generating chamber communicating with a nozzle opening and a reservoir is formed of an elastic plate, and the pressure generating chamber is expanded by elastically deforming the elastic plate by a piezoelectric vibrator which expands and contracts in an axial direction. An ink jet recording head that contracts is characterized in that it can be reduced in size and can be driven at high speed, compared to a recording head that uses flexural vibration that deforms in the plane direction.

However, if piezoelectric vibrators are arranged on a fixed substrate at high density in order to cope with high-density printing, residual vibrations of the pressure generating chamber after ink droplet ejection are caused by other pressures via the piezoelectric vibrators and the fixed substrate. There is a problem that the cross talk occurs due to unnecessary propagation of the meniscus that propagates to the generation chamber and is formed at the nozzle opening.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to prevent the residual vibration of a pressure generating chamber from being propagated to another pressure generating chamber. To provide an ink jet recording head that enables printing with high print quality.

A second object of the present invention is to provide an image forming apparatus using the same ink jet recording head.

[0006]

According to the present invention, there is provided a piezoelectric vibrator unit comprising a plurality of piezoelectric vibrators operating in a longitudinal vibration mode fixed to a fixed substrate via an adhesive layer. And a flow path unit that ejects ink droplets by receiving the displacement of the piezoelectric vibrator, in an ink jet recording head fixed by a head holder, wherein the adhesive layer has a vibration having a natural vibration period of the piezoelectric vibrator. The thickness of the layer is controlled by the spacer material so as to absorb the heat.

[0007]

The thickness of the adhesive layer is adjusted in accordance with the period of the residual vibration of the piezoelectric vibrator, and the residual vibration of the piezoelectric vibrator is absorbed by the adhesive layer to prevent propagation to other pressure generating chambers.

[0008]

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 used in the present invention.
Each surface of the pressure generating chamber 2 for pressurizing the ink, the reservoir 3 receiving the supply of ink from the outside, and the spacer 5 having the ink supply port 4 connecting the pressure generating chamber 2 and the reservoir 3 is provided with a nozzle opening 6. A nozzle plate 7 and an elastic plate 8 that changes the volume of the pressure generating chamber 2 in response to displacement of a piezoelectric vibrator described later are laminated.

The piezoelectric vibrator 9 is configured such that internal electrodes 10 and 11 having different poles in parallel with the direction of expansion and contraction have a piezoelectric constant d31 laminated with a piezoelectric material 12 interposed therebetween. As shown in FIG. 13 is fixed via an adhesive layer 14 so that one end is a free end in accordance with the arrangement pitch of the pressure generating chambers 2 and is integrated into a piezoelectric vibrator unit 15.

The flow path unit 1 and the piezoelectric vibrator unit 15 are fixed to the head holder 16 with the tip of the piezoelectric vibrator 9 abutting on the island portion 8a of the elastic plate 8 to constitute a recording head. Then, the adhesive layer 14 for joining the piezoelectric vibrator 9 and the fixed substrate 13 is formed by kneading an electrically insulating adhesive such as glass having a diameter t or beads of a polymer material with an electrically insulating adhesive. The thickness t is controlled using a material prepared by the above method. In addition,
Reference numeral 18 in the figure denotes a dummy piezoelectric vibrator that functions as a positioning member.

In this embodiment, when a drive signal is applied to the piezoelectric vibrator 9 via the flexible cable 19,
After the piezoelectric vibrator 9 contracts and expands to expand and contract the pressure generating chamber 2 and fill the pressure generating chamber 2 with ink from the reservoir 3, the pressure generating chamber 2 is pressurized and ink droplets are discharged from the nozzle opening 6. Is discharged.

After the ejection of the ink droplets, the pressure generating chamber 2 expands,
Residual vibration having a period Ta occurs with the contraction. This vibration is transmitted to the piezoelectric vibrator 9 via the elastic plate 8, but the adhesive layer 14 that selectively absorbs the vibration of the cycle Ta is interposed between the piezoelectric substrate 9 and the fixed substrate 13. Fixed substrate 1
3 is minimized. As a result, the residual vibration of the piezoelectric vibrator 9 driven to eject ink droplets does not propagate to the adjacent non-driven piezoelectric vibrator, and the cross vibration caused by the unnecessary vibration of the piezoelectric vibrator 9 is prevented. Talk can be prevented.

That is, as shown in FIG.
When the thickness t of the piezoelectric vibrator 4 increases, the period of vibration that can be absorbed tends to increase, and the amount of displacement of the piezoelectric vibrator 2 transmitted to the elastic plate 8 also decreases. Therefore, by controlling the thickness of the adhesive layer 14, the residual vibration of the pressure generating chamber 2 can be effectively attenuated.

Accordingly, it is possible to prevent the residual vibration of the piezoelectric vibrator 9 for ejecting ink droplets from propagating through the piezoelectric vibrator 9 and the fixed substrate 13 and acting on the other adjacent pressure generating chambers 2. Talk can be effectively prevented.

Next, the above-described piezoelectric vibrator unit 15
A method of manufacturing the device will be described. An internal electrode 20, 21 and a piezoelectric material 22 are alternately laminated to prepare a piezoelectric vibrating plate 23 having a piezoelectric constant d31 having a unit size and a fixed substrate 24, and an adhesive in which a gap material 25 is kneaded. 26 is applied to the fixed substrate 24 and the fixed area of the piezoelectric vibrating plate 23 (FIG. 4I). At this time, depending on the material of the fixed substrate 24, it is desirable to secure the adhesiveness by rubbing the adhesive area or applying an adhesiveness improving agent.

One internal electrode 20 of the piezoelectric vibrating plate 23
When the piezoelectric vibrating plate 23 and the fixed substrate 24 are fixed via the adhesive layer 27 having the thickness t determined by the gap material 25 when the positioning and pressing are performed so that the region in which only the ridge is formed is the fixed region (FIG. 4). (II)).

Next, slits 29, 2 from the free end side are cut by a dicing saw or wire saw cutting tool 28.
When 9, 29 and ‥‥ are formed and divided, the piezoelectric vibrator unit is completed (FIG. 4 (III)).

In the above-described embodiment, a description has been given of the piezoelectric vibrator unit in which the piezoelectric vibrator 9 and the fixed substrate 13 are fixed with their side faces facing each other. However, as shown in FIG. The same effect can be obtained even when the end face of the child 9 and the end face of the fixed substrate 13 are opposed to each other and fixed by the adhesive layer 14 in which the spacer material is kneaded.

In the above-described embodiment, the piezoelectric vibrator 9 having a piezoelectric constant d31 in which internal electrodes are laminated in parallel with the direction of expansion and contraction.
Although the piezoelectric vibrator unit using the above has been described, FIG.
(B) perpendicularly to the direction of expansion and contraction as shown in FIG.
A similar effect can be obtained by applying the present invention to a piezoelectric vibrator unit using a piezoelectric vibrator 34 having a piezoelectric constant d33 by laminating the piezoelectric material 31 with a piezoelectric material 32 interposed therebetween.

The ink jet type recording head 40 thus constructed is connected to a drive motor 42 via a timing belt 41 as shown in FIG.
The ink jet type image forming apparatus is finished by being fixed to the side of the carriage 44 that reciprocates by the surface of the carriage 44 facing the recording paper 45, and receives ink supplied from the ink cartridge 46 to eject ink droplets onto the recording paper 45. Thus, an image can be formed by a dot pattern.

[0021]

As described above, according to the present invention, a piezoelectric vibrator unit in which a plurality of piezoelectric vibrators operating in a longitudinal vibration mode are fixed to a fixed substrate via an adhesive layer,
In an ink jet recording head in which a flow path unit that ejects ink droplets by receiving a displacement of a piezoelectric vibrator is fixed by a head holder, an adhesive layer absorbs vibration of a natural vibration cycle of the piezoelectric vibrator. Since the thickness of the piezoelectric vibrator is controlled by the spacer material, the residual vibration of the piezoelectric vibrator is absorbed by the adhesive layer, and the propagation to the adjacent pressure generating chamber is eliminated, so that crosstalk can be prevented.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing one embodiment of a piezoelectric vibrator unit used in the recording head.

FIG. 3 is a diagram showing the relationship between the thickness of an adhesive layer, the period of vibration that can be absorbed, and the amount of displacement transmitted to an elastic plate.

FIGS. 4 (I) to (III) are views showing one embodiment of a method of manufacturing the above piezoelectric vibrator unit.

FIGS. 5A and 5B are diagrams showing another embodiment of the present invention.

FIG. 6 is a diagram showing an embodiment of an image forming apparatus using the ink jet recording head of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flow path unit 9 Piezoelectric vibrator of longitudinal vibration mode 13 Fixed substrate 14 Adhesive layer 17 Spacer material

Claims (8)

[Claims] 1. A piezoelectric vibrator unit comprising a plurality of piezoelectric vibrators operating in a longitudinal vibration mode fixed to a fixed substrate via an adhesive layer, and a flow path for ejecting ink droplets when the piezoelectric vibrators are displaced. An ink jet recording head comprising a unit and a head holder, wherein the adhesive layer has a layer thickness controlled by a spacer material so as to absorb a vibration of a natural vibration cycle of the piezoelectric vibrator. head. 2. The ink jet recording head according to claim 1, wherein the adhesive layer is made of a low elastic adhesive. 3. The ink jet recording head according to claim 1, wherein the adhesive layer is an electric insulating layer. 4. The ink jet recording head according to claim 1, wherein said spacer material is made of an electrically insulating material. 5. The ink jet recording head according to claim 1, wherein a side surface of the piezoelectric vibrator is fixed to the fixed substrate via the adhesive layer. 6. The ink jet recording head according to claim 1, wherein an end face of the piezoelectric vibrator is fixed to the fixed substrate via the adhesive layer. 7. The ink jet recording head according to claim 1, wherein an adhesion improving process is performed on an adhesion region of the fixed substrate. 8. A piezoelectric vibrator operating in a longitudinal vibration mode,
A plurality of piezoelectric vibrator units fixed to a fixed substrate via an adhesive layer whose thickness is controlled by a spacer material so as to absorb the vibration of the natural vibration cycle of the piezoelectric vibrator; and a displacement of the piezoelectric vibrator. An ink jet image forming apparatus in which an ink jet recording head in which a flow path unit for receiving and ejecting ink droplets is fixed by a head holder is arranged to face a recording medium, and supplies ink to the recording head from outside.