JP2002127407A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording head in which evaporation of solvent in the ink can be suppressed without sacrifice of the compliance of a reservoir. SOLUTION: Since a recess 12 forming a part of a reservoir communicates with the atmosphere through a hole 14 open to the atmosphere having a fluid resistance, vapor of ink solvent permeated a film for sealing the reservoir 3 and intruded into a recess forming a compliance part is prevented from being diffused without sacrifice of the compliance and thickening of ink is suppressed in the reservoir.

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 which supplies ink to a pressure chamber via a reservoir and pressurizes the pressure chamber by a pressure generating means.

[0002]

2. Description of the Related Art In an ink jet recording head, a piezoelectric vibrator is provided in a partial area of an elastic plate constituting a pressure chamber.
The deformation of the elastic plate of the pressure chamber due to the displacement of the piezoelectric vibrator causes a pressure change to generate ink droplets. Since the pressure change generated in the pressure chamber during ink discharge is transmitted to the reservoir through the ink supply port, this pressure change is absorbed and mitigated by providing a compliance section in the reservoir,
Stable ink ejection and ink supply are realized. For example, in Japanese Patent Application Laid-Open No. H11-129467, the concave portion forming the reservoir is sealed with a film which is easily elastically deformed such as a polymer film, and this region is opened to the atmosphere to change the pressure of the reservoir during ink ejection. Is absorbed by the deformation of the film.

[0003]

The ink in the reservoir is isolated from the atmosphere through an elastic film made of a polymer or the like having a relatively low air-shielding property. Is thickened or solidified, which causes printing failure and nozzle clogging. In order to solve such a problem, it is conceivable to form a highly air-permeable layer such as a metal on the elastic film, but there is a problem that the compliance of the reservoir 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 ink jet recording head capable of suppressing evaporation of an ink solvent without lowering the compliance of a reservoir. It is to be.

[0005]

In order to achieve the above object, according to the present invention, a reservoir, an ink supply port,
And a flow path forming substrate that partitions the pressure generating chamber, an elastic plate that seals one surface of the flow path forming substrate and receives displacement of the piezoelectric vibrator, and a nozzle opening that communicates with the pressure chamber, An ink jet that is formed of a nozzle plate that seals the other surface of the flow path forming substrate, has a compliance portion adjacent to the reservoir with the elastic plate interposed therebetween, and the compliance portion is opened to the atmosphere by one or more air opening holes. An ink jet recording head, wherein the air opening hole is longer than the shortest straight line connecting the opening surfaces at both ends and is open to the atmosphere through a long hole.

The concave portion is communicated with the atmosphere through the elongated pores, so that there is no reduction in compliance, and the diffusion of the vapor of the ink solvent that has penetrated the concave portion forming the compliance portion through the film sealing the reservoir. Is prevented, and the viscosity of the ink in the reservoir is suppressed.

[0006]

Embodiments of the present invention will be described below. FIG. 1 is a sectional view of the inkjet head. In the ink jet recording head, ink droplets are ejected from nozzle openings 1 of a nozzle plate 15 which constitutes a part of a flow path unit by driving a piezoelectric vibrator 7 housed in a plastic head holder 6 as a pressure generating means. Is discharged.

The flow path unit 5 has a structure in which a nozzle plate 15, a spacer 16, and an elastic plate 10 are bonded and laminated, and the spacer 16 is provided with an ink flow path and a space serving as a pressure chamber in a predetermined pattern. The nozzle plate 15 and the vibrating plate 10 are vertically adhered and integrated to maintain airtightness.

The nozzle plate 15 is provided with a plurality of nozzle openings 1 in a row. Correspondingly, strip-shaped elongated openings are formed in the head holder 6 in parallel with the joint surface with the flow path unit 5, and the comb-like tips of the piezoelectric vibrator 7 face from these openings. The tip (output portion) of the book is joined to the island portion 9 of the elastic plate 10.

The spacers 16 are formed from a silicon wafer or the like, and each of the cavities is partitioned into a predetermined pattern by etching the silicon wafers, and as shown in FIG. Pressure chamber 4, reservoir 3, ink supply path 2 leading from reservoir 3 to pressure chamber 4
Are appropriately formed.

The elastic plate 10 has a double structure in which a highly elastic resin film such as a PPS film is laminated on a metal plate, for example, a stainless steel plate, and a portion corresponding to each pressure chamber has an island portion on the center line on the stainless steel plate side. Each of the piezoelectric vibrators 7 is bonded to each of the island portions 9 by etching in an annular shape so as to leave 9. The region of the elastic plate 10 facing the reservoir 3 is processed so that the metal plate is removed by etching to leave only the resin film. Thereby, the pressure fluctuation of the reservoir 3 can be absorbed by the deformation of the film.

The piezoelectric vibrator 7 has a plurality of tips (output portions) arranged corresponding to the respective pressure chambers 4, and these are arranged on a single large piezoelectric vibrator in a comb-shaped slit portion at a predetermined pitch. Are formed, and the base of the array is fixed to the fixing plate 17 to form the vibrator unit 8. The ink pressure in the pressure chamber 4 changes with the expansion and contraction of the piezoelectric vibrator 7 to discharge ink droplets from the nozzle opening 1, and the ink in the reservoir 3 is supplied to the pressure chamber 4 via the ink supply path 2. 4. Fill.

[0012] As shown in FIG.
An accommodation space 18 for accommodating the vibrator unit 8 is formed, and the accommodation space 18 penetrates from the opening 13 on the joint surface with the flow path unit 5 to the opposite side.
Are inserted in such a manner that the ends of the piezoelectric vibrator 7 face the opening 13, and the fixing plate 17
Is fixed to the inner wall of the storage space 18. Then, as shown in FIG. 2, the elastic plate 1 is located at a position facing the reservoir 3 of the flow path forming unit 5 of the head holder 6.
A concave portion 12 is formed to make the elastic film 0 elastically deformable. The concave portion 12 is opened to the atmosphere through an air opening hole 14 to form a compliance portion 11.

In this embodiment, the atmosphere opening hole 14 has a surface on which the opening of the opening hole of the head holder is provided so that the resin film can respond to the ink pressure fluctuation of the reservoir 3 and can exhibit the highest possible fluid resistance. It is configured as a long hole longer than the shortest straight line connecting the concave portion 12.

According to this embodiment, when the ink in the pressure chamber 4 is pressurized by the extension of the piezoelectric vibrator 7, a part of the ink is ejected from the nozzle opening 1 as an ink droplet, and a part of the ink is supplied. Backflow from road 2 to reservoir 3. Although the pressure of the reservoir 3 tends to rise due to the backflow, the resin film elastically deforms while expelling the air in the recess 12 from the air opening hole 14 to absorb the pressure fluctuation. On the other hand, in the non-printing state, the solvent of the ink in the reservoir penetrates the resin film and diffuses as vapor into the concave portion, but since the long hole having a large fluid resistance functions as a capillary, the solvent diffuses into the atmosphere. Is alleviated. Thereby, the concave portion is maintained at a high ink vapor pressure, and therefore, the amount of vapor transmitted through the resin film is suppressed.

FIG. 2 shows a second embodiment of the recording head according to the present invention, wherein a hole 12 from the recess 12 formed in the head holder to the atmosphere is spirally extended from the surface opposite to the head holder. It is formed and penetrates. The elastic plate 10, the spacer 16,
An ink jet recording head is formed by laminating the nozzle plates 15 in this order.

According to this embodiment, a desired evaporation mitigation mechanism can be provided without changing the basic manufacturing method of the parts including the head holder 6.

FIG. 3 shows a third embodiment of the present invention, in which a part of the air opening hole 14 is formed as a mesh portion 14 '. The mesh portion 14 'can be formed by changing the manufacturing method of the head holder 6. That is, as shown in FIG. 4, the shape of the atmosphere opening hole 14 is formed to be plane-symmetrical in the joined cross section of the three parts cut at the center of the concave portion 12 constituting a part of the compliance part. This is welded or bonded to form the head holder 6. An elastic plate 10, a spacer 16, a nozzle plate 1
By stacking in the order of 5, an ink jet recording head is formed. By forming the mesh portion 14 ', the solvent vapor can be trapped in the open hole, and the diffusion of the solvent vapor of the ink can be effectively prevented.

FIG. 5 shows a fourth embodiment of the present invention, in which a zigzag or long meandering pattern is formed on the surface 23 of the air opening hole on the head holder side regardless of the shape of the air opening hole 14. A plate 20 provided with a gas flow path pattern 19 is attached, and the gas flow path pattern 19 is connected to the opening of the atmosphere opening hole 14. One end 24 of the gas flow path pattern 19 is connected to the atmosphere opening hole opening 23, and the other end 25 is open to the atmosphere. According to this embodiment, the diameter of the air opening hole 14 can be increased, and the manufacture of the head holder 6 becomes easy.

In the above-described embodiment, the formation method for ensuring the compliance of the reservoir with the elastic plate forming a part of the pressure generating chamber has been described. However, only the reservoir is sealed with another elastic plate to ensure the compliance. Obviously, a similar effect can be obtained by applying to the type to be provided.

[0020]

As described above, according to the present invention, it is possible to increase the amount of ink without forming a special air-blocking layer on the elastic film constituting the elastic plate, and ensuring a sufficiently large reservoir compliance. Stickiness can be prevented.

[Brief description of the drawings]

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

FIG. 2 shows a second example of the ink jet recording head of the present invention.
It is an assembly perspective view showing an example.

FIG. 3 shows a third example of the ink jet recording head of the present invention.
It is sectional drawing which shows Example of (a).

FIG. 4 shows a third example of the ink jet recording head of the present invention.
FIG. 3 is an assembled perspective view showing the embodiment of FIG.

FIG. 5 shows a fourth example of the ink jet recording head of the present invention.
FIG. 3 is an assembled perspective view showing the embodiment of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle opening 2 Ink supply path 3 Reservoir 4 Pressure chamber 5 Flow path unit 6 Head holder 7 Piezoelectric vibrator 8 Vibrator unit 9 Island part 10 Elastic plate 11 Compliance part 12 Recess 13 Opening 14 Air opening hole 15 Nozzle plate 16 Spacer 17 Fixing plate 18 Storage space 19 Gas flow path pattern 20 Plate 21 Electrode hole 22 Ink supply port 23 Open end of atmosphere opening hole 24 Connection hole between gas passage and atmosphere opening hole 25 Gas passage opening

Claims (4)

[Claims] A flow path forming substrate that partitions a reservoir, an ink supply port, and a pressure generating chamber; an elastic plate that seals one surface of the flow path forming substrate and receives displacement of a piezoelectric vibrator; A nozzle plate communicating with the pressure chamber, comprising a nozzle plate for sealing the other surface of the flow path forming substrate, and a compliance portion adjacent to the reservoir with the elastic plate interposed therebetween; In the above-described ink jet recording head, which is opened to the atmosphere through the air opening hole, the air opening hole is open to the atmosphere through a long hole longer than a shortest straight line connecting the opening surfaces at both ends. 2. An ink jet recording head according to claim 1, wherein the air opening hole is formed in a spiral shape. 3. An ink jet recording head according to claim 1, wherein a part of the air opening hole is formed in a mesh. 4. The recording head according to claim 1, wherein
An ink jet recording head, wherein a plate having a zigzag meandering gas flow path is attached to an opening surface on the head holder side, and one end of the air opening hole is connected to the gas flow path.