JPH0433863A - Ink jet recording head - Google Patents

Abstract

PURPOSE:To enable recording to be performed with low energy, at high speed, at high density, and at low cost by a method wherein a container of which at least a part wall is formed by an elastic wall and which seals substantially hermetically an electroconductive filler containing a substance which generates variation in phase and shows variation in volume due to variation in temperature, and an electrode for heating the filler by electrifying them are provided. CONSTITUTION:A manufacturing method which is favorable for installing an electrode 4 on an elastic wall 8 side is that the electrode is preliminarily provided onto the elastic wall 8. Manufacture of a head becomes easy by adhering or by fixing by pressure of the electrode to a substrate to which hermetically sealed container walls 71, 72 are formed There are a method of adhering a film and a method in which after filling by a filler 13, application, vacuum deposition, or sputtering is performed as a method for installing the elastic wall. For an ink chamber forming wall 10, the hermetically sealed container to be formed with the hermetically sealed container walls 71, 72 and the electrodes 3, 4 is filled by a electroconductive filler 13 containing a substance which generates variation in phase to vary its volume by heating.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet printer head.

[Prior Art] The inkjet recording method, in which images are recorded by ejecting liquid ink from nozzles, has the following advantages: it can print on plain paper, it is easily compatible with color printing, and it has a high printing speed. Due to these advantages, printers based on various ejection principles have been commercially available in recent years. A specific method of the conventionally used inkjet method is described in, for example, the Journal of the Society of Television Engineers 37(7) 540 (1983).

Typical methods include applying a pulse voltage according to the image to a piezoelectric element such as PZT, or applying heat to the ink in the ink chamber to form bubbles, thereby injecting the ink into the ink chamber. The pulse-on-demand method uses pressure to force the ink out of the nozzle, the electrostatic suction method applies a pulsed voltage according to the image to the electrodes to induce charges in the ink, and draws the ink from the nozzle toward the recording paper. Examples include a method in which ink droplets are continuously formed and the ink droplets are selectively ejected toward the recording paper by controlling the amount of charge.

A drawback of these conventional technologies is that, for example, heads using piezoelectric elements are described in Japanese Utility Model Application Publication No. 56-14305, but such heads cannot be manufactured by mechanical processing such as cutting or bonding. However, the disadvantages are that the desired resolution cannot be obtained and the cost is high. In addition, in the method using bubbles caused by heat,
High-resolution, low-cost heads are easy to obtain, but the applied temperature is over 300°C, which tends to cause part of the heater to break.Due to direct heating of the ink, the dye in the ink may decompose. However, there are drawbacks such as the inability to use highly water-resistant dyes and the difficulty in ejecting hot-melt inks, which limits the types of inks that can be used.

The electrostatic attraction method is described in USP 3060429, for example.
Although this method is disclosed in Japanese Patent Publication No. 2003-122014, it is easy to obtain a high-resolution, low-cost head, but only special ink can be used because the ink needs to have a specific electrical conductivity.

There are drawbacks such as the high voltage required for driving, which increases the cost of the driving circuit.

A method of continuously ejecting ink droplets is, for example, U
Publication S P 3598275, US P 3298
The method disclosed in Publication No. 030 requires a pump in the ink supply system, which tends to result in a large device, and although the response frequency per nozzle can be increased, it is difficult to arrange the nozzles in a high density. It is difficult to record with the arranged heads, and it is difficult to perform high-speed recording.

[Problems to be Solved by the Invention] The present invention aims to provide an inkjet recording head based on a new ejection method that can solve the problems of conventionally used inkjet recording methods as described above. This is the purpose. In other words, it is possible to implement a recording method that enables low-cost, high-density, high-speed recording, and low-energy recording, has fewer restrictions on the types of ink that can be used, and can print on plain paper. The 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 portion of the wall that substantially seals the electrically conductive filler containing a substance that undergoes a phase change and exhibits a volume change due to temperature change is made elastic. An inkjet recording head is used that has a container formed of walls and an electrode for applying electricity to and heating the filler.

The present applicant first provided an airtight container with at least a portion of the wall formed of an elastic wall and filled with paraffin, and a means for heating paraffin in this airtight container to heat the paraffin. The application was filed for an inkjet recording head that changes the volume of an ink chamber by thermal expansion accompanying a phase change from a solid state to a liquid state, increases the pressure of ink, and ejects ink from a nozzle.

It has been confirmed that by using the inkjet recording head configured in this way, it is possible to achieve low cost, high density, and an expanded range of usable ink tolerances. However, in this inkjet recording head, in order to eject ink droplets of the desired size,
- It is necessary to change the volume of the ink chamber by more than a fixed value,
For this reason, it is necessary to make the paraffin layer thick by about 2 μm or more. The present inventor discovered that the low thermal conductivity of the paraffin filled in the sealed container of such an inkjet recording head was a major obstacle to increasing the recording speed, and found that it was possible to compensate by heating. The present invention was achieved by confirming that it is possible to improve the driving frequency and droplet velocity by using an electrically conductive material as a filler containing a changeable substance and directly heating the filler by applying electricity. It is.

Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a diagram illustrating a main part of an embodiment of an inkjet recording head according to the present invention. In the figure, 1
is a head substrate, 2 is an intermediate insulating layer, 3 and 4 are electrodes, and 7
Reference numeral 1.72 indicates a wall of the sealed container, 8 an elastic wall of the sealed container, 10 an ink chamber forming wall, and 16 a nozzle plate, which has an ejection port 11 for ejecting ink toward a recording material. 1
4 is an ink inlet, which communicates with the ink tank, and ink is supplied through this port. 71, 72. The sealed container formed by 3 and 4 contains an electrically conductive filler 13 containing a substance that undergoes a phase change and volume change when heated.
is filled.

15+ and 152 are insulators for preventing the electrode 3 and the electrode 4 from coming into contact and short-circuiting when voltage is applied.

More specifically, the materials and manufacturing methods used in the inkjet recording head of the present invention include, for example, as the substrate 1, ceramics such as alumina, glass, plastics such as phenol resin, single crystal wafers such as silicon, stainless steel, etc. Metals such as brass, aluminum, duralumin, etc. can be used. In the present invention, it is particularly preferable to use a material with high thermal conductivity as the substrate in order to improve heat dissipation efficiency. Furthermore, protrusions such as fins can be provided on the outside of the substrate to improve heat dissipation efficiency.

As the intermediate insulating layer 2, silicon oxide, nitride,
Carbide, glazed glass, epoxy resin, etc. can be used. The purpose of this intermediate layer is to prevent destruction of the electrode due to heating caused by the difference in thermal expansion coefficient between the substrate and the electrode layer, and to improve the adhesion of the electrode material to the substrate.

Therefore, the middle layer is not an essential component of the present invention;
For example, if a metal is used for the substrate and the metal is directly used as an electrode for supplying electricity to the filler, it is clear that the intermediate layer is not necessarily necessary.

The electrodes 3 and 4 are made of AI, Ag, or Au.

Pt, CLI, Ni and alloys of these metals can be used. Electrodes can be made by vacuum evaporation, sputtering,
It can be provided by plating, adhesion, laminating, etching, etc., or it can be buttered. A preferred manufacturing method for providing the electrode 4 on the elastic wall 8 side is to provide the electrode on the elastic wall 8 in advance by the method described above, and then move the elastic wall provided with the electrode to the closed container wall 71, 72. By adhering or press-bonding the head to the substrate on which the head is formed, the head is manufactured or the product is manufactured.

The walls 71 and 72 of the sealed container are formed by drilling or grooving a film made of polyimide, polyamide, polyfluoroethylene, etc. by etching with an excimer laser or carbon dioxide laser, or by using a photosensitive polymer and masking it. Method of etching after exposure, glass,
A method of applying a photosensitive polymer layer on the vessel wall layer using a member such as metal, exposing it to light using a mask, and etching the photosensitive polymer layer and the member, polyimide, polyamide, polyfluoroethylene, glass It can be formed by, for example, a method in which a layer of metal or the like is provided and then cut using a dicing saw or the like.

The elastic wall 8 is made of polyimide, polyamide, polyethylene,
It can be formed from polymers such as polypropylene, polyvinyl chloride, and polyvinylidene chloride, or metals such as stainless steel, nickel, and gold. Methods for providing the elastic wall include a method of adhering a film made of the above-mentioned material, a method of filling the filler 13 and then applying it, vacuum evaporation, and sputtering.

The ink chamber forming wall 10 can be manufactured using the same processing method and material as the sealed container walls 71 and 72.

A sealed container formed by 71, 72, 3, and 4 is filled with an electrically conductive filler 13 containing a substance that undergoes a phase change and volume change when heated.

Substances that change volume due to phase change due to heating used here include beeswax, carnauba wax, and rice wax.
Natural waxes such as wax, wood wax, jojoba oil, spermaceti wax, candelilla wax, paraffin wax and its derivatives, oleic acid amide, lauric acid amide, stearic acid amide, ricinoleic acid amide, valmitic acid amide, tetrahydrofuran amide, erucic acid amide,
Amides such as N-stearyl erucamide, N-oleyl stearamide, erucic acid amide, myristic acid amide, zenacetin, toluamide, acetamide,
palmitic acid, stearic acid, behenic acid, tiglic acid,
Hexadecylmalonic acid, didocosylmalonic acid, decylmalonic acid, eicosylmalonic acid, tocosylmalonic acid, tetradecylmalonic acid, eicosylthioglycolic acid, hexadecylmalonic acid.

Acid, dodecylthiomalic acid, sorbic acid, ketoglutaric acid, stearylacylglutamic acid, 2-acetonaphthonebehenic acid, monolauryl terephthalate, monostearyl terephthalate, 12-hydroxystearic acid, 16
-Organic acids such as hydroxyhexadecanoic acid and metal salts of these acids, dodecanol, tetradecanol, hexadecanol, eicosanol, docosanol, tetracosanol, hexacosanol, octacosanol, 9-dodecen-1-ol, mili sil alcohol, 9-tetracen-1-ol, 9-hexadecen-1-ol, 9
- eicosen-1-ol, 13-tocosen-1-ol, pinene glycol, hinokiol, butynediol, nonanediol, isophthalyl alcohol, medicerin, terephthalyl alcohol, hexanediol, decanediol, dodecanediol, tetradecanediol, Alcohols such as hexadecanediol, tocosandiol, tetracosandiol, terpineol, phenylglycerin, eicosandiol, octanediol, phenylpropylene glycol, benzoylacetone, diacetobenzene, benzophenone, tricosanone, heptacanosanone, heptatriacontanone, hemp Compounds such as ketones such as triacontanone, stearone, lauron, and cyanisole, and esters of the above acids and alcohols such as glycerin, diethylene glycol, and ethylene glycol can be used.

The compound to be used from among these series of compounds is selected appropriately by considering the desired phase change temperature, volume change rate, thermal stability, corrosivity to the head member, workability in the head manufacturing process, etc. In order to achieve this purpose, it is also effective to mix two or more types of compounds. For use under normal usage conditions, the phase transition point or 40 to 200
Preferably it is at °C.

Most of the substances used here that change volume due to phase change due to heating are highly insulating materials. Therefore, in order to make the filler electrically conductive, aluminum, magnesium, gold, silver, copper, zinc, tin, nickel, tungsten,
Metal powders such as beryllium, molybdenum, indium, iron, chromium, and titanium, conductive metal oxides such as tin oxide, indium oxide, and zinc oxide, conductive pigments such as carbon black, phthalocyanine, and naphthalocyanine, and long-chain alkyl. A dissociative organic salt compound such as a metal salt of sulfonic acid having a long-chain alkyl, a conductive polymer compound such as polypyrrole, polyaniline, polythiophene, or polyacetylene, etc. can be added to the filler. It is also preferable to add particles of polyethylene, silica gel, cellulose, crosslinked polyacrylic acid ester, crosslinked polystyrene, etc. whose surfaces are coated with the above-mentioned electrically conductive substances to the filler in order to increase electrical conductivity.

The mixing ratio of a substance that changes volume due to a phase change due to heating and the above-mentioned conductivity imparting material is determined by the electrical conductivity of the substance itself that changes volume due to a phase change, the volume change ratio of the phase change substance, and the conductivity imparting material. It should be determined by considering factors such as the electrical conductivity of the material, the thickness of the filler layer, the distance between the electrodes, and the voltage that can be applied between the electrodes, but it is generally 5 to 80% by volume. , preferably in a range of 20 to 50 volumes 9o.

The substance whose volume changes due to phase change due to heating and the conductivity imparting material can be mixed by stirring and dissolving during heating, dispersion using a ball mill or the like, kneading using a roll mill or the like. When the conductivity-imparting material is a powder, a surfactant or a polymer dispersion material may be added to the filler for the purpose of preventing sedimentation or aggregation of the powder.

The thickness of the filler layer is appropriately determined depending on factors such as the shape of the sealed container and the rate of change in volume due to phase change of the filler. It is preferable to determine the shape of the closed container so that the volume is 1 to 3 times the volume of the ink droplet in order to obtain an appropriate ink droplet size and velocity.

The insulators 15+ and 152 can be formed using photopolymer, silicon oxide, magnesium oxide, aluminum oxide, tantalum oxide, silicon nitride, zirconium oxide, or the like.

[Example] The present invention will be explained in more detail by giving more specific examples of producing a head.

After applying a photopolymer layer to a thickness of approximately 4 μW on a stainless steel plate with a thickness of 1 mm, pattern exposure and etching were performed to directly form 128 lines on the stainless steel plate.
Width approximately 40μm, length 12III111 interval approximately 20ti
The closed container walls 71 and 72 were formed so that m grooves were formed. Separately, 128 electrodes with a width of about 40 μm and an interval of about 20 μm were formed by etching the aluminum layer of a polyimide film with a thickness of about 5 μm on which about 100 aluminum evaporated layers were provided. did. The photosensitive resin was exposed and etched in a pattern to form an ink chamber with a shape corresponding to the sealed container. 9-Tetracene-1- is placed inside the wall of the previously prepared sealed container.
The oar was filled with 40Vo1% aluminum powder dispersed therein. The inkjet recording head of the present invention was fabricated by aligning and overlapping and press-bonding a polyimide film on which patterned electrodes were formed and an ink chamber forming member to the sealed container after filling.

When an ejection test was conducted with the above head using a water-based inkjet ink with a viscosity of 1.5 ep, IKHz
Stable droplets were obtained even at higher frequencies.

"Effects of the Invention" As is clear from the above explanation, in the present invention, (
1) Since a solid-liquid phase change due to heating is used to eject ink, high temperatures are not required as in the case of forming ink vapor, and the life of the head can be extended.

(2) Since the heating section does not come into direct contact with the ink, a wide variety of inks can be used, including inks that use highly water-resistant dyes and inks that are solid at room temperature, expanding the range of uses for the printer.

(3) The filling material filled in the sealed container that changes phase with temperature changes is electrically conductive, and the filling material itself generates heat, so energy can be used efficiently, simplifying the cooling device and power consumption. This makes it possible to increase the response frequency. In addition, the filler is heated uniformly, and there is no need for heat conduction, unlike in a head provided with a separate heating section, and the response frequency and ink ejection speed can be increased.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating an embodiment of an inkjet recording head according to the present invention. 1: Substrate, 2: Intermediate insulating layer, 3, 4: Electrode, 71.72
: Sealed container wall, 8: Sealed container elastic wall, 10: Ink chamber forming wall, 11: Discharge port, 12: Ink (ink chamber), 1
3: filler, 14: ink inlet, 151, 152: insulator, 16: nozzle plate.

Claims (1)

[Claims] A container having at least a portion of the wall formed of an elastic wall and substantially sealing an electrically conductive filling material containing a substance that undergoes a phase change and a volume change due to a temperature change; An inkjet recording head characterized by having an electrode for heating a material.