KR100359107B1 - A method for manufacturing actuator of inkjet printhead - Google Patents

Abstract

The present invention relates to an actuator manufacturing method of an inkjet printhead, which enables a printing operation to be performed smoothly by deformation due to thermal expansion and shape memory action of the shape memory alloy regardless of the residual compressive stress of the second thin film. In order to achieve the above object, the present invention comprises the steps of depositing a second thin film 12 on the substrate 30, and maintaining a flat state at room temperature on the second thin film 12 to the austenite start temperature Forming a diaphragm 10 by depositing the thin film shape memory alloy 11 that is warped and deformed by thermal expansion of the shape memory alloy 11 and returned to a flat state at the austenite termination temperature when heated; Etching a portion of the substrate 30 so that the second thin film 12 of the diaphragm 10 is partially exposed, and being in contact with at least both ends of the thin film memory alloy 11. It is provided as a step having a heating means 40 to generate the displacement required for the ink spray on the diaphragm 10 by thermal expansion and shape memory action according to the temperature change of the thin film shape memory alloy 11 to perform printing. There are main features.

Description

A method for manufacturing actuator of inkjet printhead

The present invention provides a method of manufacturing an actuator of an inkjet printhead, which enables a printing operation to be performed smoothly by deformation by thermal expansion and shape memory of a shape memory alloy regardless of the residual compressive stress of the second thin film. It is about.

In general, inkjet printheads mainly use the Drop On Demand (DOD) method of spraying ink in the form of droplets, which do not need to charge or deflect ink droplets, and do not require high pressure. There is an advantage that the ink droplets can be easily ejected and recorded even under pressure, and the use of the ink is rapidly increasing. Representative injection methods using the piezoelectric method and the thermal bubble jet method are used.

At this time, the piezoelectric method is to change the volume in the chamber in which ink is filled by deforming the diaphragm using a piezoelectric material so that the ink is ejected, and the thermal bubble jet method causes the ink in the chamber to be heated by resistance to generate in the chamber. The ink is ejected while the air expands due to the bubble.

However, the piezoelectric method is difficult to process the piezoelectric element, and in particular, the processing cost is expensive, and since the thermal bubble jet method mainly uses water-soluble ink, the residue remains from the thermal decomposition of ink components between the ink and the heater at high temperatures when the ink is heated. Cogulation (cogation) that accumulates on the surface of the surface may be caused, the preservation of the document due to ink ejection is reduced, in particular, the life of the heat generating resistor is shortened.

In addition, there is a method using a magnetic field as a method of ejecting ink, but in such a method may cause a nozzle clogging due to electrode corrosion, power consumption is very large, it is difficult to apply practically because the selection of magnetic materials is difficult.

On the other hand, it is cheaper than the piezoelectric element, and as a driving means to prevent the chemical change of the ink or the clogging of the nozzle without using water-soluble ink, recently, the thin film shape memory alloy 1 as shown in FIG. At this time, the thin-film shape memory alloy 1 is not used alone, but is integrally coupled with the second thin film 2 having a residual compressive stress so as to operate simultaneously.

In other words, the thin-film shape memory alloy 1 has a shape memory so as to be deformed in a flat state at a predetermined temperature. The thin-film shape memory alloy 1 mainly has thermal oxidation property having a property of bending deformation due to internal residual compressive stress. The diaphragm is constituted by allowing the second thin film 2 made of silicon to be integrally stacked.

The residual compressive stress in the second thin film 2 is usually about 300 MPa, and this stress causes the initial deformation of the diaphragm.

Therefore, when the power source is not input to the thin film shape alloy 1 through the electrode 3 or initially, the diaphragm is caused by the residual compressive stress of the second thin film 2. When the power is input and the thin film shape memory alloy 1 is heated to a predetermined temperature, the thin film shape memory alloy 1 is already stored as shown in FIG. Since the volume of the flow path plate 5 is reduced in the shape of the chamber 5a, the ink filled in the chamber 5a is discharged through the nozzle 6a.

When the power supply is stopped again, the thin-film memory alloy 1 gradually cools, and the diaphragm is warped and deformed by the residual compressive stress of the second thin film 2, and refills ink into the chamber 5a. .

However, since the residual compressive stress of the second thin film 2 in the above structure can be formed only by a specific material and a process, this has a disadvantage in that the material selection and manufacturing process of the second thin film 2 are constantly limited.

In addition, since the deformation area of the diaphragm must be very large in order to generate deformation due to residual compressive stress of the initial driving, there is a problem that the density of the nozzle is reduced.

The present invention is to compensate for the above-mentioned problems, the present invention is to make the diaphragm bend deformation by thermal expansion by heating of the thin-film memory alloy irrespective of the residual compressive stress of the second thin film material and manufacturing process Its main purpose is to enable diversification.

In another aspect, the present invention is to improve the compactness of the nozzle to provide a clearer print quality.

1 is a cross-sectional view showing an inkjet printhead using a conventional thin-film memory alloy,

FIG. 2 is a cross-sectional view illustrating a state in which the thin film shape memory alloy is returned to a stored shape in the inkjet printhead of FIG. 1;

3 is a cross-sectional view of an inkjet printhead according to the present invention;

4 is a cross-sectional view showing a state in which the diaphragm is deformed by thermal expansion of the thin film-shaped memory alloy in the state of FIG.

5 is a cross-sectional view showing a state in which the thin film shape memory alloy is returned to the stored shape in the diaphragm of the present invention;

FIG. 6 is a cross-sectional view showing a state in which the shape memory alloy of FIG. 5 is deformed by thermal expansion after returning to the shape memorized;

7 is a graph showing the displacement of the diaphragm over time of the present invention;

8 is a cross-sectional view showing another operating state of FIG.

9 is a graph showing the displacement of the diaphragm with time of FIG. 8.

<Description of the symbols for the main parts of the drawings>

10 diaphragm 11 thin film shape memory alloy

12: second thin film 20: euro plate

30 substrate 40 heating means

50: nozzle plate

In order to achieve the above object, the present invention comprises the steps of depositing a second thin film on a substrate,

The second thin film is kept flat at room temperature. When heated to the austenite start temperature, the diaphragm is deposited by depositing a shape-memory thin-film memory alloy that is warped by thermal expansion and returns to a flat state at the austenite end temperature. Forming step,

Etching a portion of the substrate to expose a portion of the second thin film of the diaphragm;

And providing a heating means to contact at least both ends of the thin film shape memory alloy, thereby causing displacement required for ink injection to the diaphragm by thermal expansion and shape memory according to temperature change of the thin film shape memory alloy. The main feature is that the printing is performed.

Hereinafter, described in detail with reference to the accompanying drawings a preferred embodiment of the present invention.

3 shows a printhead according to the invention, wherein 10 is a diaphragm.

The diaphragm 10 is a driving means laminated between the flow path plate 20 and the substrate 30. A thin film-shaped memory alloy 11 is provided on the flow path plate 20 side of the vibration plate 10, and the substrate ( The thin film shape alloy 11 and the second thin film 12 are integrally bonded to the second thin film 12 on the 30 side.

A heating means 40 is provided on the flow path plate 20 side of the diaphragm 10 to heat the thin-film memory alloy 11, and discharges ink in a direction corresponding to the vibration plate 10 of the flow path plate 20. The nozzle plate 50 in which the nozzle 51 to make is provided is provided.

In addition, a portion of the substrate 30 penetrates up and down to form a predetermined space.

For this configuration, first, the second thin film 12 is deposited on the substrate 30, but in this case, the second compressive film 12 is in a state in which residual compressive stress is removed.

The thin film-shaped memory alloy 11 is deposited on the upper portion of the second thin film 12 while the thin film-shaped memory alloy 11 is kept flat at room temperature. This results in bending deformation, and when the austenite finish temperature is reached, the shape memory is brought into a flat state.

The thin film shape memory alloy 11 is deposited on the second thin film 12 to provide the diaphragm 10, and then a portion of the substrate 30 is etched to form a space part. A portion of the second thin film 12 of 10) is exposed.

In addition, the thin film-shaped memory alloy 11 integrally coupled with the second thin film 12 is provided such that the heating means 40 contacts at least both ends.

When the thin film shape alloy 11 is heated or naturally cooled through the heating means 40 in the driving structure provided as described above, the substrate of the diaphragm 10 may be formed by thermal expansion and shape memory of the thin film shape memory alloy 11. 30) The portion exposed to the side space portion is bent or unfolded while the printing is made.

Meanwhile, the thin film shape alloy 11 of the diaphragm 10 mainly uses Ni-Ti-based, Ni-Ti-Cu-based, and Ni-Ti-Pb-based, and the second thin film 12 includes silicon nitride, silicon oxide, It is most preferable to use polysilicon or silicon impregnated with impurities (p, n type Doping).

In particular, the second thin film 12 may be used as a thermal passivation, and in this case, all metal materials are possible.

In addition, the heating means 40 for heating the diaphragm 10 is simply made of an electrode, it is also applicable to the structure of directly heating the thin film-shaped memory alloy (11).

In addition, the heating means 40 may be formed as a heater so that the thin film shape alloy 11 is heated in an electrically indirect manner.

As described above, the configuration of the present invention is almost the same as before, but only the second thin film 12 of the present invention has the most prominent feature in that no residual compressive stress exists.

Therefore, in the room temperature state in which power is not input to the heating means 40, the diaphragm 10 maintains a flat state as shown in the drawing. In this state, the diaphragm 10 is supplied with power to the diaphragm 10. When the thin film shape alloy 11 is heated until the austenite start temperature, the thin film shape alloy 11 generates a compressive stress due to internal thermal expansion. In this case, a bending moment acts so that a part of the diaphragm 10 on the side of the space formed on the substrate 30 is deformed as quickly as a predetermined displacement δ1 as shown in FIG.

As the diaphragm 10 is deformed, ink is filled into the chamber 21 from one side of the flow path plate 20. When the heating temperature of the thin-film memory alloy 11 reaches the austenite finish temperature, the diaphragm 10 The thin-film memory alloy 11 in (10) attempts to return to the previously memorized shape and eventually becomes flat as shown in FIG.

At this time, due to the shape memory effect of the diaphragm 10, a very high pressure is instantaneously formed in the chamber 21 to discharge the ink filled in the form of droplets through the nozzle 51.

On the other hand, when the thin film-shaped memory alloy 11 to be heated above the austenite end temperature, the thin film-shaped memory alloy 11 again generates a compressive stress due to internal thermal expansion, so that the diaphragm 10 is predetermined as shown in FIG. The deflection is caused by the displacement δ2.

In such a state, when the power supply to the electrode 40 is stopped and naturally cooled to below the end point of martensite, the thin film shape memory alloy 11 is restored to its original room temperature while maintaining the flat state as shown in FIG. 7. do.

Comprehensive series of operating displacements according to the above action it can be seen that the displacement curve as shown in FIG.

On the other hand, by varying the material or the thickness of the thin film shape memory alloy 11 and the second thin film 12, etc., once the austenite finish temperature is reached, the flat state becomes flat and the thin film shape memory alloy 11 is again austenite. When heated above the end temperature of the knight, as shown in FIG. 8, the diaphragm 10 may be deformed in a curved direction toward the chamber 21.

In this deformation, the diaphragm 10 has a shape that is curved toward the chamber 21 in the state in which the diaphragm 10 is inflated to the space side of the substrate 30, and thus the movement width of the diaphragm 10 is increased very fast and at the same time, thereby increasing the soil output of ink through the nozzle. You can do it.

As described above, the present invention can reduce the size of the diaphragm 10 while preventing the bending deformation from being caused at room temperature, while increasing the compactness of the nozzle.

Therefore, it is possible to prevent the degradation of the resolution due to the decrease in the nozzle density, which is the most problematic problem in the printhead using the shape memory alloy, thereby providing a clearer picture quality.

In addition, since the material of the second thin film 12 can be more widely selected, the design can be diversified.

Therefore, the present invention merely improves the compactness of the nozzle and the miniaturization of the injection cell by improving the action due to the bending deformation of the diaphragm 10 by the thermal expansion action and the shape memory action of the thin film shape memory alloy 11. The wide selection of materials of the two thin films 12 allows for a wider variety of fabrication and increases productivity.

In particular, since the jetting force for discharging the ink provides a clearer image quality, there is a very useful effect of improving the performance.

Claims (2)

Depositing a second thin film 12 having no residual compressive stress on the substrate 30; The second thin film 12 maintains a flat state at room temperature, and when heated to an austenite start temperature, is warped and deformed by thermal expansion, and the thin film shape memory alloy 11 is shaped to return to a flat state at an austenite end temperature. Vapor deposition to form a diaphragm 10, Etching a portion of the substrate 30 to expose a portion of the second thin film 12 of the diaphragm 10; Providing heating means (40) in contact with at least one end of the thin film shape memory alloy (11); Actuator manufacturing method of the ink-jet printhead having a printing to be carried out by causing the displacement required for the ink injection of the diaphragm 10 by the thermal expansion and shape memory action according to the temperature change of the thin film shape memory alloy 11 . The method of claim 1, wherein the second thin film 12 Actuator manufacturing method of an inkjet printhead which is a thermal protective film.