JPH0431059A - Manufacture of ink jet head - Google Patents

Abstract

PURPOSE:To form an opening part having a highly dimensionally accurate diameter and prevent nozzle forming members from being vibrated and deformed due to the pressure of an ink upon discharge by a method wherein the nozzle forming members are made up by applying resin membranes to the plate members having an opening part larger in diameter than that on the resin membrane. CONSTITUTION:A nozzle forming member 22 is formed through the lamination of plate members 45 having an opening part 46 and resin members 41 having an opening part 23 smaller in diameter than the opening part 46. An ink 28 is supplied from the opening part 46 on the side of the plate member 45 of the nozzle forming member 22 and discharged from a nozzle 23 on the side of the resin membrane 41. By the laminate formation of the plate members 45 for enhancing the mechanical strength and the resin membranes 41 capable of forming the diameter of the opening pat with a good dimensional accuracy, the requirements for both the mechanical strength and the dimensional accuracy of the diameter of the opening part can be satisfied. The opening part 23 of the resin membrane 41 is made smaller in shape than the hole on the ink supply side and the opening part of the plate member 45 on the ink supply side is made larger in diameter than the opening part 23 on the ink discharge side, whereby the nozzle forming members 22 can be made up without increasing resistance to an ink passage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of manufacturing an inkjet head used in a printer or the like that forms an ink image on a recording medium such as recording paper by ejecting ink droplets.

[Conventional technology]

An example of the structure of a conventional inkjet head disclosed in Japanese Patent Publication No. 60-8953 is shown in No. 6M. The above structure includes a nozzle forming member 102 having a plurality of nozzles 103.
and a piezoelectric transducer 101 placed behind it and in direct contact with the recording ink 109. Piezoelectric transducer 1
01 is formed by joining a rod-shaped metal member 105 and a rod-shaped piezoelectric ceramic member 104, and is fixed to the nozzle forming member 102 with a screw 108 via a spacer 107. This structural example has an impact bar piece 106 made of metal to improve the impact characteristics of the piezoelectric transducer. The piezoelectric transducer 101 vibrates so as to be displaced in a direction generally perpendicular to the nozzle forming member 102. The shape of the nozzle 103 is
It is formed into a conical shape so that its cross-sectional area decreases as it approaches the ink 109 discharge opening.

Conventionally, as methods for manufacturing the nozzle forming member 102, electroforming methods, etching methods, wire discharge methods, and the like have been proposed. Further, the electroforming method includes a photoelectroforming method in which a plate-like member is formed after selectively applying a resist on a conductor plate;
There is a master electroforming method in which a mask shape is created and then the shape is transferred. However, no matter which of the above manufacturing methods is used, they are all made of a single metal member.

[Problem to be solved by the invention]

In the prior art photoelectroforming method or etching method described above, the shapes of the front and back sides of the nozzle openings are similar, making it difficult to arrange the nozzle intervals closely. Also, the nozzle could not be made into a conical shape. In the master electroforming method, a huge amount of cost is required to manufacture the mask, and furthermore, the mask has a short lifespan, and productivity is low, making it extremely expensive. Products manufactured using the wire discharge method also had the drawback of being expensive because the manufacturing time was extremely long.

[Means to solve the problem]

The method for manufacturing an inkjet head of the present invention includes a step of forming a photosensitive resin into a film, a step of exposing both sides of the photosensitive resin film, and forming an opening by removing either the exposed or unexposed region. and a step of attaching the resin film to a plate-like member having an opening having a hole diameter larger than that of the resin film to form a nozzle forming member.

〔Example〕

Embodiments of the present invention will be described based on the drawings.

FIG. 1 is a perspective view of a printer using an inkjet head according to the present invention. In the figure, a recording medium 1 is wound around a platen 4 and is pressed by a feed roller 2.about.3. Guided by the guide shaft 6.7 and parallel to the platen axis 10
An inkjet head 9 is mounted on a carriage 8 that can be moved to
is installed and configured. The inkjet head 9 has a plurality of nozzle openings that can be controlled to eject ink droplets independently by applying an external driving voltage, and is scanned in the platen axis direction 10 and selectively ejects ink droplets from the nozzles to the recording medium. An ink image is formed on 1. Recording medium 1
is Graten 4. The recording medium 1 is conveyed in the sub-scanning direction 5 perpendicular to the scanning direction by the rotation of the feed roller 2.degree. 3, and printing is performed on the recording medium 1.

FIG. 2 is a sectional view showing an embodiment of an inkjet head according to the present invention. FIG. 3 is a sectional perspective view of the main part. However, the present invention is not limited thereto. A piezoelectric transducer 2 is connected to the frame 20 via a base material 25.
1 and a nozzle forming member 22 are stacked and fixed.

The piezoelectric transducer 21 has a multilayer structure including a piezoelectric material 32 made of piezoelectric ceramic, an electrode layer 33 made of at least a thin gold layer on one side, and a metal layer 31 made of an alloy of iron and nickel on the opposite side. In this embodiment, a lead zirconate titanate (PbTiO2-PbZr03 solid solution) thin plate is used for the piezoelectric material 32, but barium titanate (BaTi03) and lithium niobate (LiNb03) are also used.
, mononotium tantalate (LiTa0a), etc. may be used. The electrode layer 33 is formed using methods such as vapor deposition, sputtering, and plating. In the configuration of this embodiment, chromium 0. 1μm, nickel 0.
It was formed by vapor deposition in the order of 1 μm and gold 0.1 μm. The nozzle forming member 22 is composed of a metal thin film having a plurality of nozzles 23.

The vicinity of the piezoelectric transducer 21 and nozzle 23 is filled with ink. The piezoelectric transducer 21 is displaced by a driving voltage applied from the flexible substrate 27, and the recording ink 2 near the nozzle is
8 is increased to cause ink droplets to be ejected from the nozzle 23.

FIG. 4 shows a sectional view of the nozzle forming member 22 formed according to this embodiment. A plate-like member 45 having an opening 46 and an opening 23 (with a hole diameter smaller than the opening 46).
A resin film 41 having a nozzle) is laminated.

The ink 28 is supplied from the opening 46 of the nozzle forming member 22 on the plate member 45 side, and is ejected from the nozzle 23 on the resin film 41 side. The diameter of the opening on the surface from which the ink 28 is ejected has a large effect on print quality, and therefore requires highly accurate dimensions. For this purpose, it is necessary to make the nozzle forming member 22 as thin as possible and form the opening hole diameter with high precision.

On the other hand, vibration and deformation of the nozzle forming member 22 due to the pressure of the ink 28 during ejection, deformation when the nozzle forming member 22 is joined,
Also, deformation due to external forces such as contact with paper must not occur. For this purpose, the nozzle forming member 22 must be made thicker. In conventional manufacturing methods, the nozzle forming member 22 is made thicker to increase its mechanical strength at the expense of dimensional accuracy of the opening hole diameter. In the present invention, a plate-like member 45 that increases mechanical strength and a resin film 41 that can form an opening with good dimensional accuracy are laminated. This makes it possible to simultaneously satisfy mechanical strength and opening hole diameter dimensional accuracy.

Further, the shape of the opening 23 in the resin film 41 was made smaller than that on the ink supply side, and the diameter of the opening in the plate member 45 at the opening on the ink supply side was made larger than that of the opening 23 on the ink discharge side. Therefore, the nozzle forming member 22 can be configured without increasing the ink flow path resistance.

The method for manufacturing an inkjet head according to the present invention will be explained step by step with reference to FIGS. 5(a) to 5(e), which roughly show the manufacturing steps.

(a) Liquid photosensitive resin is dropped onto a planar substrate and rotated at high speed to form a film to form a photosensitive resin film 41.

The membrane pressure can be adjusted by changing the polyimide resin concentration, rotation speed, and rotation time. In this example, a methacrylic acid ester solution of polyamic acid was used as the liquid photosensitive resin, but the present invention is not limited to this, and a hexapolyimide resin solution or the like may be used by introducing an acrylic photosensitive group. After film formation, prebaking is performed at 80°C to 100°C for 140 to 70 minutes. Solvent is removed by pre-baking. If the prebaking is insufficient, there will be a problem of decreased photosensitivity due to residual solvent. Furthermore, excessive prebaking may cause minute cracks in the resin film or cause changes in developability in subsequent steps.

(b) A mask substrate 42a is brought into close contact with one side of the photosensitive resin film 41, and ultraviolet (UV) exposure is performed using a high-pressure mercury lamp. The exposure amount was 70-500 mJ/cm2.

(C) A mask substrate 42b is brought into close contact with the surface opposite to the exposure surface, and UV exposure is performed using a high-pressure mercury lamp. The photosensitive resin is crosslinked by photopolymerization reaction by UV exposure. The exposed area becomes insolubilized by crosslinking.

(d) After exposure, the resin film is developed and the unexposed areas are removed.

At this time, since the photosensitive resin has a relatively high viscosity, the rate of diffusion into the developer in the unexposed area is slow.

Therefore, in this example, development was performed while applying ultrasonic waves. For this reason, there was no residue in the unexposed areas, and good development could be performed. After development, cleaning was performed while applying ultrasonic waves, and good results were obtained. In this embodiment, a negative type photosensitive resin is used, but the present invention is not limited to this, and a positive type photosensitive resin may be used.

After development and cleaning, the resin film 41 is cured by heating.

Curing was performed at r180-350'C for 1-3 hours while open. In this example, a methacrylic acid ester solution of polyamic acid was used as the liquid photosensitive resin, so when heated, an imide ring was formed through a dehydration condensation reaction, resulting in a stable polyimide resin film. Through the above steps, the opening 43a and the opening 43b having a larger hole diameter are formed.

In this example, N-methyl-2-pyrrolidone (NMP) and N are used as solvents for the photosensitive resin.

A mixture of the same amount of N-dimethylacetamide (DMAC) was used. However, in addition to these, N, N dimethylformamide, methyl cellosolve, ethylene glycol dimethyl ether, tetrahydrofuran, etc., and the above-mentioned NM
P and DMAC may be used alone or in combination.

(e) The resin film 41 is attached and bonded to the plate member 45 having the opening 46 to obtain the nozzle forming member 22. The opening 46 has a larger hole diameter than the opening 43b of the resin film 41, and is attached so that the opening 46 and the opening 43b are substantially concentric. The plate member 45 and the resin film 41 are bonded together using a bonding material that is compatible with the liquid photosensitive resin. In this example, a polyamic acid solution was used in which tetracarboxylic dianhydride and diisocyanate were subjected to a ring-opening polymerization reaction in NMP. In addition to this, bonding may be performed using epoxy, acrylic resin, or the like.

In this embodiment, an alloy of iron and nickel is used for the plate-shaped member, but other metals, ceramics, etc. can be arbitrarily selected. Although the opening 46 was formed by press working, it may also be formed by drilling, laser processing, or the like.

If openings are formed in the resin film by an etching removal method without using a photosensitive resin as in this embodiment, more complicated steps are required. Moreover, the side wall of the nozzle opening is scraped and becomes tapered. This makes it difficult to arrange the nozzles 23 in a high density. Further, when a polyimide resin having good heat resistance and chemical resistance is used for the resin film, hydrazine or the like is used as an etching liquid. This hydrazine has higher reactivity than other etching solutions and is extremely harmful to the human body. Therefore, sufficient safety measures must be taken when using it. In other words, compared to forming a nozzle forming member using the conventional method or etching removal method,
Can be formed at low cost with fewer steps. Furthermore, since an appropriate solvent can be selected and used, safety measures can be easily taken.

The nozzle forming member formed as described above is bonded to a plurality of piezoelectric transducers 21 aligned and fixed on a base material 25 using a bonding material 24. Since the thickness of the bonding material 24 is a factor that determines the ejection characteristics of recording ink droplets,
1 and the nozzle opening 23 must be defined.

Therefore, in this embodiment, this is achieved by mixing spherical, long spherical, or 8M-shaped interval regulating members made of glass, metal, etc. of uniform size into the bonding material 24.

〔Effect of the invention〕

According to the present invention, the nozzle forming member is formed by laminating two members, and since the resin film on the ink ejection side is thinner than the opening, the diameter of the opening can be formed with high precision. Since a resin film with a nozzle is formed on the surface of a plate-like member such as a highly rigid metal plate, the nozzle forming member may vibrate and deform due to the pressure of ink during ejection.

Deformation when joining the nozzle plate or deformation due to external forces such as contact with paper no longer occurs. Furthermore, by providing an opening on the recording ink supply side with an opening having a diameter larger than that of the opening on the ink discharge side, pressure applied by the piezoelectric transducer can be efficiently converted into ink droplet velocity. Further, since a resin film having nozzles is formed by exposing, developing and curing the photosensitive resin, the number of bending coefficients can be significantly reduced compared to the conventional method. Therefore, an inkjet head with excellent print quality can be provided at a low cost.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of a recording apparatus equipped with an inkjet head of the present invention. FIG. 2 is a sectional view of the inkjet head of this embodiment. FIG. 3 is a cross-sectional perspective view of the inkjet head of this embodiment. FIG. 4 is a detailed sectional view of the nozzle opening of the nozzle forming substrate according to this embodiment. FIG. 5 is a process diagram showing the approximate manufacturing process of the inkjet head according to this embodiment. FIG. 6 is a plan view and a sectional view of a conventional inkjet head.・Recording medium ・Platen ・Inkjet spatula ・Piezoelectric transducer ・Nozzle forming member ・Nozzle ・Ink ・Piezoelectric material ・Resin film ・Mask substrate ・Opening in resin film ・Plate member ・Opening on the side of plate member Seiko Epson Co., Ltd. Attorney Kizo Suzuki (and 1 other person) Figure 2 Figure 3 Figure 2 4/ Figure 4 46: M0 dinner (b) (C) 85 Figure 10/: Piezoelectric conversion Vessel (a) (b) Figure 6

Claims (1)

[Scope of Claims] A nozzle forming member having a plurality of nozzles arranged to face a recording medium, and a piezoelectric transducer, and configured such that ink is filled between the nozzle forming member and the piezoelectric transducer. A method for manufacturing an inkjet head, comprising: forming a photosensitive resin into a film; exposing both sides of the photosensitive resin film; and removing either the exposed or unexposed part to form an opening. A method for manufacturing an inkjet head, comprising: a step of attaching the resin film to a plate-like member having an opening having a hole diameter larger than an opening of the resin film to form a nozzle forming member.