JP2915494B2 - Inkjet recording head - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ink jet printer head.

[Prior art] An ink jet recording method in which a liquid ink is ejected from a nozzle to record an image is capable of printing on plain paper, being easily compatible with colorization, having a high printing speed, and the like. Due to the advantages described above, printers based on various ejection principles have been marketed in recent years. The specific method of the ink jet method conventionally used is described in, for example, the Journal of the Institute of Television Engineers of Japan 37 (7) 540 (1983).

Typical examples of the method include applying a pulse voltage according to an image to a piezoelectric element such as PZT, or applying heat to the ink in the ink chamber to form air bubbles, thereby forming a bubble in the ink chamber. A pulse-on-demand method in which pressure is applied to extrude ink from a nozzle, an electrostatic suction method in which electric charges are induced in ink by applying a pulse voltage according to an image to an electrode, and ink is suctioned from a nozzle to a recording paper side, There is a method in which ink droplets are continuously formed, and the amount of charge is controlled to selectively fly the ink droplets toward the recording paper.

As a drawback of these conventional techniques, for example, a head using a piezoelectric element is described in, for example, Japanese Utility Model Laid-Open Publication No. 56-14305, but such a head is manufactured by mechanical processing such as cutting and joining. However, there is a drawback that a desired resolution cannot be obtained or the cost increases. Also, in the method using bubbles by heat, a high-resolution and low-cost head is easily obtained, but the applied temperature is 30 ° C.
Hot melt inks where the heater is apt to be destroyed due to the high temperature of 0 ° C. or higher, the dye in the ink is decomposed because the ink is directly heated, and a dye having high water resistance cannot be used. However, there is a disadvantage that the ink that can be used is restricted, for example, the ejection becomes difficult.

The electrostatic suction method is, for example, a method disclosed in U.S. Pat.No. 3,060,429, but a high-resolution, low-cost head is easy to obtain, but a special ink is required because the ink needs to have a specific electric conductivity. Only ink can be used. There are drawbacks such as a high driving voltage and a high driving circuit cost.

A method for continuously ejecting ink drops is, for example, US
P3596275, the method disclosed in USP3298030, etc., requires a pump in the ink supply system,
Although the apparatus tends to be large, and the response frequency per nozzle can be increased, it is difficult to perform recording with a head having nozzles arranged at high density, and it is difficult to perform high-speed recording.

[Problems to be Solved by the Invention] The present invention can solve the problems of the conventionally used inkjet recording method as described above.
It is an object of the present invention to provide an inkjet recording head based on a new ejection method. In other words, it is possible to implement a recording method that enables low-cost, high-density, high-speed recording, low-energy recording, and has few restrictions on inks that can be used, and enables printing on plain paper. An object of the present invention is to provide an inkjet recording head.

[Means for Solving the Problems] In order to achieve the above object, at least a part of a wall which substantially seals an electrically conductive filler containing a substance which undergoes a phase change by a temperature change and shows a volume change is elastically deformed. An ink jet recording head having a container formed by walls and electrodes for supplying electricity to the filler and heating the filler is used.

The present applicant has previously formed at least a part of the wall with an elastic wall, and provided a closed container filled with paraffin, and provided a heating means for the paraffin in the closed container, and heated the paraffin to form the paraffin. The present inventors have applied for an ink jet recording head that changes the volume of an ink liquid chamber due to thermal expansion accompanying a phase change from a solid state to a liquid state, raises the pressure of ink, and ejects ink from nozzles. It has been confirmed that the use of the ink jet recording head configured as described above can achieve a low cost, a high density, and an expanded range of acceptable ink usable. However,
In this ink jet recording head, in order to eject ink droplets of a target size, it is necessary to change the volume of the ink chamber by a certain value or more. For this reason, the paraffin layer is thickened to about 2 μm or more. There is a need to.
The present inventor has found that the low thermal conductivity of paraffin filled in a closed container in such an ink jet recording head is a major obstacle to increasing the recording speed. Using an electrically conductive material as a filler containing a substance that changes, and by directly heating the filler by energization, it has been confirmed that the drive frequency and the droplet speed can be improved. It is.

Hereinafter, a description will be given based on examples of the present invention. FIG. 1 is a main part configuration diagram for explaining an embodiment of an ink jet recording head according to the present invention. In the figure, 1 is a substrate for the head, 2 is the intermediate insulating layer, 3 and 4 electrodes, 7 _1, 7 ₂ closed vessel walls, the closed container elastic wall 8, 10 ink chamber forming wall,
Reference numeral 16 denotes a nozzle plate, which has a discharge port 11 for jetting toward a recording material. Reference numeral 14 denotes an ink inlet, which communicates with the ink tank, and ink is supplied through this opening. The hermetically sealed container formed by 7 ₁ , 7 ₂ , 3 and 4 is filled with an electrically conductive filler 13 containing a substance which undergoes a phase change by heating and changes in volume. 15 ₁ , 1
5 _2, the electrodes 3 and 4 are in contact when a voltage is applied, an insulator for preventing a short circuit.

More specifically, the material and manufacturing method used for the ink jet recording head of the present invention are, for example, as the substrate 1, ceramics such as alumina, glass, plastic such as phenolic resin, single crystal wafers such as silicon, stainless steel, and brass. , Aluminum, and metals such as duralumin can be used. In the present invention, it is particularly preferable to use, as the substrate, a material having a large thermal conductivity in order to improve heat radiation efficiency. Further, projections such as fins for improving heat radiation efficiency can be provided outside the substrate.

As the intermediate insulator layer 2, silicon oxide, nitride, carbide, glazed glass, epoxy resin, or the like can be used. This intermediate layer is for the purpose of breaking down the electrode due to heating caused by the difference in thermal expansion coefficient between the substrate and the electrode layer, improving the adhesion of the electrode material to the substrate, and the like. Therefore, the intermediate layer is not an essential component of the present invention.For example, in the case where a metal is used for the substrate and the metal is used as an electrode for directly supplying the filler, the intermediate layer is not necessarily required. It is clear.

As the electrodes 3 and 4, Al, Ag, Au, Pt, Cu, Ni, and alloys of these metals can be used. Electrodes are vacuum deposited,
It can be provided or patterned by a method such as sputtering, plating, bonding, lamination, and etching. A preferable manufacturing method for providing the electrode 4 on the elastic wall 8 side is to provide an electrode on the elastic wall 8 in advance by the above-described method, and the elastic wall provided with the electrode is connected to the closed container wall 7 ₁ , 7 ₂ of the formed substrate, by bonding or crimping, the manufacture of the head becomes easy.

The closed container walls 7 ₁ and 7 ₂ are made of a method of perforating or grooving a film of polyimide, polyamide, polyfluoroethylene, or the like by etching with an excimer laser, a carbon dioxide gas laser, or the like. A method of etching after exposure, using a member such as glass or metal, further applying a photosensitive polymer layer on the vessel wall layer, exposing with a mask, and etching the photosensitive polymer layer and the member After forming a layer of polyimide, polyamide, polyfluorinated ethylene, glass, metal, or the like, it can be formed by a cutting method using a dicing saw or the like.

The elastic wall 8 can be formed of a polymer such as polyimide, polyamide, polyethylene, polypropylene, polyvinyl chloride, or polyvinylidene chloride, or a metal such as stainless steel, nickel, or gold. As a method of providing the elastic wall, there are a method of bonding a film made of the above material, a method of filling the filler 13, and then applying, vacuum depositing, or sputtering.

Ink chamber forming wall 10 can be produced by processing methods and materials similar to the closed container wall 7 _1, 7 _2.

In the closed container formed by 7 ₁ , 7 ₂ and 3, 4
An electrically conductive filler 13 containing a substance that undergoes a phase change by heating and changes in volume is filled.

The substances used here that change volume by phase change by heating include natural waxes such as beeswax, carnauba wax, rice wax, wood wax, jojoba oil, whale wax, candelilla wax, paraffin wax and the like. Derivatives, oleic amide, lauric amide, stearic amide, ricinoleic amide, palmitic amide, tetrahydrofuran amide, erucamide, N-stearyl erucamide, N-oleyl stearamide, erucamide, myristic acid Amides such as amide, phenacetin, toluamide, acetamide, palmitic acid, stearic acid, behenic acid, tiglic acid, hexadecylmalonic acid, didocosylmalonic acid, decylmalonic acid, eicosylmalonic acid, docosylmalonic acid, tetradecylmalonic acid Eicosylthioglycolic acid, hexadecylthiomalic acid, dodecylthiomalic acid, sorbic acid, ketoglutaric acid, stearylacylglutamic acid, 2-acetonaphthonebehenic acid, monolauryl terephthalate, monostearyl terephthalate, 12-hydroxystearic acid , Organic acids such as 16-hydroxyhexadecanoic acid and metal salts of these acids, dodecanol, tetradecanol, hexadecanol, eicosanol,
Docosanol, tetracosanol, hexacosanol,
Octacosanol, 9-dodecene-1-ol, myricyl alcohol, 9-tetracene-1-ol, 9-hexadecene-1-ol, 9-eicosen-1-ol,
13-docosen-1-ol, pinene glycol, hinokiol, butynediol, nonanediol, isophthalyl alcohol, mesicerin, terephthalyl alcohol, hexanediol, decanediol, dodecanediol, tetradecanediol, hexadecanediol,
Alcohols such as docosanediol, tetracosanediol, tvneol, phenylglycerin, eicosanediol, octanediol, phenylpropylene glycol, benzoylacetone, diacetbenzene, benzophenone, tricosanone, heptacosanone, heptatriacontanone, and hentria Compounds such as ketones such as contanone, stearone, lauron, and dianisole, and esters of the above acids with alcohols such as glycerin, diethylene glycol, and ethylene glycol can be used.

What to use in these series of compounds is appropriately selected in consideration of desired phase change temperature, volume change rate, thermal stability, erosion property to the head member, workability in the head manufacturing process, and the like. It is also effective to mix two or more compounds to achieve the purpose.
For use under normal operating conditions, the phase transition point should be 40-200 ° C.
Is preferred.

Most of substances used here that change in volume by a phase change due to heating are highly insulating materials. Therefore, in order to make the filler electrically conductive, metal powder such as aluminum, magnesium, gold, silver, copper, zinc, tin, nickel, tungsten, beryllium, molybdenum, indium, iron, chromium, titanium, tin oxide, oxide Dissociation of conductive metal oxides such as indium and zinc oxide, conductive pigments such as carbon black, phthalocyanine and naphthalocyanine, quaternary ammonium compounds having long-chain alkyls, and metal salts of sulfonic acids having long-chain alkyls An organic salt compound, a conductive high molecular compound such as polypyrrole, polyaniline, polythiophene, polyacetylene, or the like can be added to the filler. It is also preferable to add particles such as polyethylene, silica gel, cellulose, cross-linked polyacrylate, cross-linked polystyrene, etc., to the filler, on the surface of which the above-mentioned electric conductive substance is coated, in order to increase the electric conductivity.

The mixing ratio between the substance that changes in volume due to the phase change due to heating and the above-described conductivity-imparting material is the electric conductivity of the substance that changes in volume by the phase change, the volume change ratio of the substance that changes in phase,
It should be determined in consideration of factors such as the electrical conductivity of the conductivity-imparting material, the thickness of the filler layer, the distance between the electrodes, and the voltage that can be applied between the electrodes, but is generally 5 to 80 volumes. %, Preferably in the range of 20 to 50% by volume.

Mixing of the substance which changes in volume due to the phase change by heating and the conductivity-imparting material can be performed by a method such as stirring and melting at the time of heating, dispersion by a ball mill or the like, or kneading by a roll mill or the like. When the conductivity-imparting material is a powder, a surfactant or a polymer dispersant can be added to the filler for the purpose of preventing the powder from settling or agglomerating.

The thickness of the filler layer is appropriately determined by factors such as the shape of the closed container, the rate of change in volume due to the phase change of the filler, and the like. It is preferable to determine the shape of the closed container so as to be 1 to 3 times the volume of the ink droplet in order to obtain an appropriate size and speed of the ink droplet.

Insulator 15 _1, 15 ₂ photopolymer, silicon oxide, magnesium oxide, aluminum oxide, tantalum oxide, silicon nitride, can be formed using a zirconium oxide.

[Examples] The present invention will be described in more detail by giving more specific examples of head production.

After applying a photopolymer layer to a stainless steel plate with a thickness of 1 mm so as to have a thickness of about 4 μm, pattern exposure and etching are performed, and 128 directly, a width of about 40 μm, a length of 12 mm and a spacing of about 20μm grooves were formed closed container wall 7 _1, 7 ₂ as being formed of. Apart from this, about 10
An aluminum layer of a polyimide film having a thickness of about 5 μm provided with an aluminum vapor deposition layer of 0 ° is etched in a pattern to obtain a width of about 40 μm and a spacing of about 20 μm.
The photosensitive resin having 128 electrodes formed thereon was subjected to patternwise exposure and etching to form a liquid container having a shape corresponding to the closed container. 9 in the wall of the sealed container made earlier
-Tetracene-1-ol in which 40% aluminum powder of 1% was dispersed was filled. The polyimide film on which the patterned electrodes were formed and the ink liquid chamber forming member were superposed and pressure-bonded to the filled closed container to form an ink jet recording head of the present invention.

When a discharge test was performed with the above head using an aqueous inkjet ink having a viscosity of 1.5 cp, stable droplets were obtained even at a frequency of 1 KHz or more.

[Effects of the Invention] As is clear from the above description, in the present invention,
(1) Since the solid-liquid phase change due to heating is used for discharging the ink, a high temperature is not required unlike the case of forming the vapor of the ink, and the life of the head can be extended. (2) Since the heating section does not come into direct contact with the ink, various kinds of inks such as an ink using a dye having high water resistance and an ink which is solid at normal temperature can be used, and the use of the printer can be expanded. (3) Since the filler filled in the closed container, which changes in phase due to a change in temperature, is electrically conductive, and the filler itself generates heat, energy can be efficiently used.
The cooling device is simplified, the power consumption is reduced, and the response frequency can be increased. In addition, the filler is uniformly heated, and heating by heat conduction is required as in a head provided with a separate heating unit. Therefore, the response frequency and the ink discharge speed can be increased.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram illustrating an embodiment of an ink jet recording head according to the present invention. 1: substrate, 2: intermediate insulating layer, 3, 4: electrode, 7 ₁ , 7 ₂ : closed container wall, 8: closed container elastic wall, 10: ink chamber forming wall, 11: discharge port, 12: ink (ink chamber), 13: filler, 14: ink inlets, 15 _1, 15 _2: insulator, 16: nozzle plate.

Claims (1)

(57) [Claims] 1. A container having an elastic wall at least a part of which substantially seals an electrically conductive filler containing a substance which undergoes a phase change due to a temperature change and shows a volume change,
An electrode for supplying electricity to the filler and heating the filler.