KR19990041106A - Printhead - Google Patents

Abstract

The present invention relates to a printhead having a heat dissipation means for rapid heat dissipation in the process of cooling a thin film-shaped retaining alloy, thereby improving reliability by increasing an operating speed. A substrate having a diaphragm covering thereon; A thin film type retaining alloy provided on the substrate to cover the diaphragm to vibrate the diaphragm while changing its shape according to temperature change; Heat dissipation means provided on an upper portion of the thin film type suppression alloy to actively release heat when the thin film type suppression alloy is cooled to increase a cooling rate; A flow path plate provided at an upper portion of the substrate and provided with a liquid chamber communicating with the thin film-type storage alloy and having a flow path formed at one side of a wall surface surrounding the liquid chamber so that a recording liquid flows into the liquid chamber; And a nozzle plate provided on the flow path plate and having a nozzle having a smaller area than the liquid chamber area so that the recording liquid can be ejected in the form of droplets when the thin film-shaped suppression alloy is changed in shape.

Description

Printhead

The present invention relates to a printhead, and more particularly, it is possible to manufacture a compact and semiconductor thin film by allowing a recording liquid to be injected by deformation in the process of phase change of the thin film-shaped retaining alloy and to quickly release heat. By manufacturing using a manufacturing process, the process is simplified and particularly relates to a printhead with improved operating speed.

In general, the widely used printhead uses a DoD On Demand (DOD) method. This DOD method is increasingly used because it does not need to charge or deflect recording liquid droplets, does not require high pressure, and can easily print by spraying the recording liquid droplets under atmospheric pressure. Typical spraying principles include a heating spray method using a resistance and a vibration spray method using a piezo-electric.

Fig. 1 is for explaining the principle of the heating spray method, which has a chamber a1 in which recording liquid is built, and has an injection hole a2 from the chamber a1 toward the recording material. At the bottom of the chamber a1, on the opposite side, a resistor a3 is embedded to cause the air to expand. Therefore, the bubble inflated by the resistance causes the recording liquid inside the chamber a1 to be pushed out to the injection port a2, and the recording liquid is ejected toward the recording material by the force.

However, this heating spray method causes a chemical change since the recording liquid is heated to heat, and the recording liquid adheres to the inner diameter of the injection hole (a2), causing clogging, and also has a short lifespan of the heat generating resistor. Documents need to be used, which results in poor document retention.

FIG. 2 is for explaining the principle of the vibrating jetting method by the piezoelectric element, and there is also a chamber b1 in which recording liquid is incorporated, and there is an injection hole b2 from the chamfer b1 toward the recording material. Piezoelectric elements (Piezo Transducer) is embedded in the bottom opposite the injection port is configured to cause vibration.

As described above, when the piezoelectric element b3 causes vibration at the bottom of the chamber b1, the recording liquid is pushed out to the injection hole b2 by the vibration force, and thus the recording liquid is transferred to the recording material by the vibration force. To be sprayed.

As the spraying method by vibrating the piezoelectric element does not use heat, there is a wide range of choice of the recording liquid, but it is difficult to process the piezoelectric element, and in particular, the operation of attaching the piezoelectric element to the bottom of the chamber b1 is difficult. Since it is difficult, there exists a problem that mass productivity falls.

In addition, a conventional shape memory alloy is used to discharge the recording liquid. Japanese Unexamined Patent Publication Nos. 57-203177, 63-57251, Pyeong 4-247680, Pyeong 2-265752, Pyeong 2-308466, and Pyeong 3-65349 disclose examples of printheads in which shape memory alloys are used. . Conventional embodiments include a plurality of shape memory alloys having different phase transformation temperatures and different thicknesses, which are configured to be bent and deformed, and those configured to be bent by a combination of the elastic member and the shape memory alloy.

However, the printhead using the conventional shape memory alloy is difficult to miniaturize the size of the head and the density of the nozzle is low, the resolution is not good, and the aspect is difficult to manufacture. In addition, the shape memory alloy used is not a thin film but a thick film having a thickness of 50 μm or more, which causes disadvantages such as high power consumption during heating and long cooling time, low operating frequency, and low printing speed.

In order to solve the various problems as described above, the present applicant causes the recording liquid to be injected while the pressure of the liquid chamber is changed by the deformation generated during the phase change process of the thin film-shaped storage alloy, thereby generating the actuation force of the shape memory alloy. ), The nozzle clogging phenomenon is reduced and the deformation amount of the thin film is large. Therefore, the thin film-type memory alloy can be manufactured in small size to increase the density of the nozzle to increase the resolution, and the thin film to the substrate using the semiconductor thin film manufacturing process. Since a shape memory alloy can be deposited and a required amount of displacement can be obtained, a recording liquid ejecting apparatus and a method of a printhead in which mass productivity is increased are among prior applications.

An object of the present invention relates to an improvement of a pre- filed printhead, and an object of the present invention is to provide a heat release means for rapid heat release in the process of cooling the thin film-shaped retaining alloy, thereby increasing the operation speed to improve reliability To provide a printhead.

1 is a cross-sectional view of a conventional heated printhead,

2 is a cross-sectional view of a conventional piezoelectric element type printhead;

3a, b, c are cross-sectional views of the printhead of the present invention;

4 is a diagram showing a heat emission curve of the present invention.

<Description of Symbols for Main Parts of Drawings>

10 substrate 11 space part

12: thin-film shape memory alloy 13: vibration plate

14 heat release means 15 pyroelectric film

15a: insulating layer 15b: upper and lower electrodes

16: Europan 17: liquid chamber

18: Euro 19: nozzle plate

20: nozzle 21: recording liquid

In order to achieve the above object, the present invention provides a substrate having a space portion at a lower portion and a diaphragm covering the space portion; A thin film type retaining alloy provided on the substrate to cover the diaphragm to vibrate the diaphragm while changing its shape according to temperature change; Heat dissipation means provided on an upper portion of the thin film type suppression alloy to actively release heat when the thin film type suppression alloy is cooled to increase a cooling rate; A flow path plate provided at an upper portion of the substrate and provided with a liquid chamber communicating with the thin film-type storage alloy and having a flow path formed at one side of a wall surface surrounding the liquid chamber so that a recording liquid flows into the liquid chamber; And a nozzle plate provided on the flow path plate and having a nozzle having an area smaller than that of the liquid chamber so that the recording liquid can be ejected in the form of droplets when the thin film-shaped suppression alloy is changed in shape.

The present invention uses a semiconductor thin film manufacturing process using a semiconductor thin film manufacturing process to solve the disadvantages of the conventional piezoelectric method and the method of using the air expansion by heating and the method using a conventional shape memory alloy By forming a portion of the substrate and etching a portion of the substrate to form a space in which the thin film-type storage alloy can vibrate, a printhead is formed to form droplets by the vibration of the thin film-type storage alloy.

The shape memory alloy is deposited on a substrate using a semiconductor thin film manufacturing process and then heat-treated to form a thin film-type memory alloy. Therefore, a flat shape is achieved in the mother state. The deposited thin film storage alloy may have residual compressive stress in martensite, and may change the magnitude of residual compressive stress according to deposition conditions, heat treatment temperature, and time. When a portion of the substrate is etched to form a space portion, the thin film-shaped suppression alloy is warped and deformed due to buckling due to residual compressive stress. When the thin film storage alloy is heated, the thin film storage alloy becomes a matrix and tries to change to a flat state. At this time, the liquid volume decreases and the recording liquid is ejected. During cooling, bending deformation occurs due to residual compressive stress, and recording liquid is refilled at this time. This process is repeated to perform continuous recording liquid injection.

In the present invention, in particular, the thin film-type suppression alloy can be heated by electric resistance to rapidly increase the temperature, while cooling is relatively slow compared to the heat generation, and thus the printing speed is slowed due to a long time until discharge of the droplets. In order to compensate for this, a film made of a pyroelectric material is formed on top of the thin film-type suppression alloy, and an electric field is applied between the films, thereby actively dissipating heat upward.

In this case, when the film is installed to actively dissipate heat, the actuator operates quickly due to the relatively high temperature rise when the electric field is heated on the thin film-type storage alloy, and when the film is cooled, the heat is not generated in the thin film-type storage alloy. The pyroelectric film removes heat and cools quickly. Therefore, the forced heat dissipation structure having such a structure increases the time for returning and increases the printing speed.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a cross-sectional view of the printhead of one embodiment of the present invention. The diaphragm 13 is formed in the substrate 10, and the diaphragm 13 covering the space 11 is provided on the substrate 10. And the thin film-shaped storage alloy 12 is provided on the surface of the diaphragm 13. In addition, a flow chamber plate 16 covering the upper portion of the substrate 10 is provided, and a liquid chamber 17 in which the recording liquid 21 is accommodated is formed directly on the thin film-type storage alloy 12. Further, a flow path 18 through which the recording liquid 21 flows is provided in the center of the flow path plate 16, and the flow path 18 and the liquid chamber 17 communicate with each other.

In addition, a nozzle plate 19 coupled to the upper portion of the flow path plate 16 is provided, and the nozzle plate 19 is formed with a nozzle 20 corresponding to the liquid chamber 17 formed in the flow path plate 16. In addition, the nozzle 20 corresponds to the thin film storage alloy 12 exposed toward the liquid chamber 17. When the thin film storage alloy 12 is deformed, the pressure of the liquid chamber 17 changes, and the recording liquid 21 is liquid. It is sprayed on the paper via the nozzle 20 in an enemy state. The thin-film shape memory alloy 12 is a shape memory alloy which is changed in phase with temperature to cause deformation. The material is mainly composed of titanium (Ti) and nickel (Ni), and its thickness is about 0.3 μm to 5 μm. It is about a micrometer. And the diaphragm 13 is comprised from 0.5 micrometer-10 micrometers positive thickness, and the magnitude | size of the liquid chamber 17 is preferably about 100 micrometers-500 micrometers in length, and about 100 micrometers-5000 micrometers in length. The substrate 10 may be made of glass, polymer, nickel, stainless steel, or the like.

In addition, the thin film-shaped storage alloy 12 composed of a shape memory alloy has a direction according to the manufacturing method. The present invention relates to a one-way thin film shape memory alloy. The diaphragm 13 and the thin film storage alloy 12 are deposited on the surface of the substrate 10 made of a material such as silicon. Deposition is mainly the method of sputter-deposition and laser ablation.

If the crystallization is performed by heat treatment at a constant temperature for a certain time, the bending deformation is caused by residual tensile stress in the parent phase. Thereafter, while the end temperature of martensite is cooled to about 40 ° C. to 70 ° C., the mother phase becomes martensite to form a flat plate. In addition, when the lower portion of the thin film-type storage alloy 12 is etched, a space 11 is formed on the substrate 10 formed of a silicon wafer, and the diaphragm 13 is exposed to the space 11.

By the above method, the substrate 10, the diaphragm 13, and the thin film-shaped storage alloy 12 are manufactured, and then the flow path plate 16 and the nozzle plate 19 are selectively formed on the upper or lower portion of the substrate 10. The printhead of the present invention is constructed.

The thin film-shaped retaining alloy 12 of the printhead fabricated according to the present invention becomes a flat plate at martensite and is deformed into a shape when the temperature is raised to a set temperature, that is, the phase termination temperature of about 50 ° C. to 90 ° C., and the bending deformation is caused by the residual tensile stress. The recording liquid 21 is ejected as it is.

In addition, the present invention is provided with a heat dissipation means 13 for rapidly dissipating heat on the upper portion of the thin-film-type storage alloy 12 to increase the cooling rate of the thin-film-type storage alloy 12. The heat dissipation means 14 includes a pyroelectric film 15 for dissipating heat according to a voltage difference, and upper and lower electrodes 15b are formed on the upper and lower portions of the pyroelectric film 15, respectively, and the lower electrode 15b and An insulating layer 15a is provided between the thin film storage alloys 12.

According to the present invention configured as described above, the thin film-shaped storage alloy 12 is continuously changed in phase with temperature change, and vibration occurs due to deformation in this process, and the recording liquid 21 is sprayed in the state of droplets through the nozzle 20. . The diaphragm 13 and the thin film type retaining alloy 12 remain in an unfolded state in an initial state in which the thin film type retaining alloy 12 is not heated. In addition, when a current is applied to the thin-film-type storage alloy 12, heat is generated by its own resistance, and when it is heated above the set temperature, the film is changed into a parent phase and warped. When the thin film-shaped retaining alloy 12 is heated, it is warped and deformed by the residual tensile stress therein. At this time, the volume of the liquid chamber 17 is expanded, and the recording liquid 21 flows into the liquid chamber 17 along the flow path 18. .

When the current is cut off, the thin film-shaped suppression alloy 12 is lowered below the set temperature, and in this process, the internal residual tensile stress of the thin film-shaped suppression alloy 12 disappears, and thus is restored to its original state by the elastic force of the diaphragm 13. As a result, the thin film-shaped storage alloy 12 and the diaphragm 13 are unfolded in an initial state. In addition, during the unfolding process, the internal pressure of the liquid chamber 17 is increased and compressed, and at the same time, the recording liquid 21 is ejected through the nozzle 20. In addition, while the heating and cooling of the thin film storage alloy 12 occur continuously, the recording liquid is ejected and printing proceeds.

In addition, the cooling rate of the thin film-type storage alloy 12 is increased by the heat dissipation means 14 during the cooling process. When power is applied to the electrode 15b, heat is actively radiated from the pyroelectric film 15 according to the voltage difference, thereby increasing the cooling rate. Therefore, the vibration speed, that is, the operating frequency of the thin film storage alloy 12 and the diaphragm 13 is increased, thereby improving the printing speed.

As described above, according to the present invention, the diaphragm vibrates together in accordance with the phase change of the thin film-type suppression alloy, and in this process, the recording liquid is injected into the droplet state through the nozzle. In addition, a pyroelectric film that actively dissipates heat according to a voltage difference is provided on the thin film-type storage alloy. Therefore, the operation speed of the thin-film type memory alloy is increased, such that the printing speed is improved.

Claims (12)

A substrate having a space provided at a lower portion thereof and having a diaphragm covering the space formed thereon; A thin film type retaining alloy provided on the substrate to cover the diaphragm to vibrate the diaphragm while changing its shape according to temperature change; Heat dissipation means provided on an upper portion of the thin film type suppression alloy to actively release heat when the thin film type suppression alloy is cooled to increase a cooling rate; A flow path plate provided at an upper portion of the substrate and provided with a liquid chamber communicating with the thin film-type storage alloy and having a flow path formed at one side of a wall surface surrounding the liquid chamber so that a recording liquid flows into the liquid chamber; And And a nozzle plate provided on the flow path plate and having a nozzle having a smaller area than the liquid chamber area so that the recording liquid can be ejected in the form of droplets when the thin film-shaped suppression alloy is changed in shape. The printhead of claim 1, wherein the thin-film-type storage alloy is a shape memory alloy mainly composed of titanium (Ti) and nickel (Ni). The printhead of claim 1, wherein the thin film-shaped retaining alloy has a thickness of 0.3 μm to 5 μm. The printhead of claim 1, wherein the substrate is made of silicon. The printhead of claim 1, wherein the substrate is made of glass. The printhead of claim 1, wherein the substrate is a polymer. The printhead of claim 1, wherein the substrate is made of metal such as nickel or stainless steel. The printhead of claim 1, wherein the diaphragm has a thickness of about 5 μm to 10 μm. The method of claim 1, wherein the thin film-shaped retaining alloy is bent and deformed together with the diaphragm by residual tensile stress when heated to a mother phase end temperature or more, and the recording liquid is replenished into the liquid chamber. And a cooling liquid below the end temperature of martensite to be changed into martensite, thereby deforming to the original flat plate by the elasticity of the diaphragm, wherein the recording liquid is ejected through the nozzle in the form of droplets. 10. The printhead of claim 9, wherein the mother phase end temperature is about 50 ° C to 90 ° C and the martensite end temperature is about 40 ° C to 70 ° C. The printhead according to claim 1, wherein the heat dissipation means is a pyroelectric film that emits heat according to a voltage difference. The upper and lower electrodes of claim 11, wherein an insulating layer is formed on the thin film type suppression alloy, a pyroelectric layer is provided on the insulating layer, and upper and lower electrodes for applying current to the pyroelectric layer on the upper and lower sides of the pyroelectric layer, respectively. Printhead, characterized in that provided.