JPH10250076A - Method and unit for jetting recording liquid for printer head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance printing speed by forming a diaphragm of a thin film shape- memory alloy and a second thin film having residual compression force on a substrate, providing an oscillation space for the diaphragm by etching a part of the substrate thereby regulating deformation and recovery force of the diaphragm and increasing the frequency. SOLUTION: A space section 11 is formed vertically through a substrate 10 and the upper part thereof is covered with a diaphragm 12 comprising a thin film shape- memory alloy 12a and a second thin film 12b having regulable deformation and recovery force which is then mounted, immediately thereon, with a channel plate 13 provided with a chamber 14 for containing a recording liquid 20. The channel plate 13 is provided with a main channel 15 for passing the recording liquid 20 and a liquid jet port 17 communicating with the main channel 15 and a nozzle 19 corresponding to the liquid chamber 14 is made in a nozzle plate 18 provided above the channel plate 13. When power is fed from a power supply section to electrodes at the opposite ends of the alloy 12, heat is generated by its own resistance and the temperature is raised. Consequently, the shape-memory alloy 12 is flattened and the pressure in the liquid chamber 14 is raised. When current supply is interrupted, it is reset to expanded state and the pressure is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION

The present invention relates to a recording liquid ejecting apparatus for a printer head and a method thereof, and more particularly, to a diaphragm vibrating due to a temperature change of a thin film shape memory alloy, adjusting a pressure of a liquid chamber, and Second with residual compressive stress
A thin film is deposited on a thin film shape memory alloy, the amount of deformation of the diaphragm can be easily adjusted, and the restoring force can be adjusted, so that the size can be reduced and the manufacturing process can be simplified. The present invention relates to a liquid ejecting apparatus and a method thereof.

[0002]

2. Description of the Related Art A widely used printer head is a DOD (Drop and Demand) system. This DOD method does not need to charge or deflect the recording liquid droplets, does not require high pressure, and can easily print by ejecting the recording liquid droplets immediately under atmospheric pressure. Therefore, it is gradually being used. Representative injection principles include a heating injection method using a resistor and a vibration injection method using a piezoelectric element.

FIG. 1 is for explaining the principle of the heating type jetting method.
There is an ejection port a2 facing the recording material from the chamber a1, and a chamber a on the opposite side of the ejection port a2 is provided.
A resistor a3 is buried in one bottom portion to cause expansion of air. Therefore, the bubbles expanded by the resistance heating push the recording liquid inside the chamber a1 to the ejection port a2, and the recording liquid is ejected toward the recording material by the force.

FIG. 2 is for explaining the principle of the vibration type ejection method using a piezoelectric element. Similarly, there is a chamber b1 in which a recording liquid is provided.
There is an ejection port b2 from 1 to the recording material, and a piezoelectric element is buried in the bottom opposite to the ejection port to generate vibration.

As described above, when the piezoelectric element b3 vibrates at the bottom of the chamber b1, the recording liquid is ejected by the ejection port b by vibrating force.
The recording liquid is ejected to the recording material by the vibration force. Since the ejection method using the vibration of the piezoelectric element does not use heat, there is an advantage that the selection range of the recording liquid is large.

Further, a conventional printer head uses a shape memory alloy to discharge a recording liquid. JP 57
-203177, JP-A-63-57251, JP-A-4-
247680, JP-A-2-265752, JP-A-2-3
08466, JP-A-3-65349 discloses an embodiment of a printer head using a shape memory alloy.
The conventional embodiment has a configuration in which a large number of shape memory alloys having different phase transformation temperatures and different thicknesses are combined to bend and deformed, and are configured to be bent and deformed by a combination of an elastic member and a shape memory alloy. And others.

[0007]

However, the above-mentioned heating type jet method has a problem that a chemical change occurs due to heating of the recording liquid, and such recording liquid adheres to the inner surface of the ejection port a2 to cause clogging. However, there is a drawback that the life of the heating resistor is short, and the storage stability of the document is poor because a water-soluble recording liquid must be used.

[0008] In addition, the above-described injection method using the vibration of the piezoelectric element has a problem in that mass production is poor because the processing of the piezoelectric element is difficult, and particularly, the work of attaching the piezoelectric element to the bottom of the chamber b1 is difficult.

Further, the conventional printer head using a shape memory alloy has problems that it is difficult to reduce the size of the head, the density and resolution of the nozzles are low, the manufacturing is difficult, and the mass productivity is poor. In addition, the shape memory alloy used is not a thin film but a thick film with a thickness of 50 μm or more. Therefore, power consumption during heating is large, cooling time is long, operating frequency is low, and printing speed is slow. There's a problem.

In order to solve the above various problems, the present inventor changes the pressure in the liquid chamber by vibration generated by a change in the temperature of the thin film shape memory alloy so that the recording liquid is ejected. Has already filed. According to the printer head filed earlier, the clogging of the nozzle is reduced due to the large acting force of the thin film shape memory alloy, and the deformation amount of the thin film shape memory alloy is large. The density can be increased to increase the resolution, and a thin film shape memory alloy can be easily manufactured using a semiconductor thin film manufacturing process and a substrate etching process, so that mass productivity is improved.

The present invention relates to an improvement of the previously filed printer head. An object of the present invention is to couple a second thin film capable of adjusting the amount of deformation and restoring force of a diaphragm to a thin film shape memory alloy by using a semiconductor thin film manufacturing process, and to reduce bending deformation in a process of cooling the thin film shape memory alloy. When restoring to the state, the restoring force is increased, and after ejecting the recording liquid, the time required for the diaphragm to restore to the state of bending deformation is shortened, thereby increasing the operating frequency and improving printing speed. And
Another object of the present invention is to provide a recording liquid ejecting apparatus for a printer head and a method thereof, in which the strength of the diaphragm is increased and the possibility of damage due to external impact is reduced.

[0012]

In order to achieve the above object, a recording liquid ejecting apparatus for a printer head according to the present invention comprises:
A diaphragm comprising a thin film shape memory alloy of a shape memory alloy material whose shape changes according to a temperature change, and at least one or more second thin films coupled to the thin film shape memory alloy to adjust the shape change amount; A power supply for generating a temperature change of the thin film shape memory alloy, and a liquid chamber for storing the recording liquid, which is provided on the thin film shape memory alloy, is formed on one side of a wall surface surrounding the liquid chamber; A flow path plate having a flow path formed so that the recording liquid flows therein, and installed on the flow path plate so that when the thin film changes shape, the recording liquid is ejected in the form of droplets. A nozzle plate formed with a nozzle having an area smaller than the liquid chamber area of the flow path plate.

The present invention solves the disadvantages of both the conventional method using a piezoelectric element and the method using air expansion by heating, and the conventional method using a shape memory alloy. A diaphragm composed of a thin film shape memory alloy and a second thin film having a residual compressive stress is formed on a substrate, and a part of the substrate is etched to form a space where the diaphragm can vibrate. An object of the present invention is to provide a recording liquid ejecting apparatus that forms droplets by vibrating a plate.

Such a spraying device forms a thin film shape memory alloy by performing heat treatment after vapor deposition on a substrate by a sputtering method. Therefore, it has a flat shape in the mother phase state.
The second thin film is also configured to be bonded to the thin film shape memory alloy by using a semiconductor thin film manufacturing process. The deposited second thin film can retain residual compressive stress,
The magnitude of the residual compressive stress can be changed depending on the deposition conditions or the material. When a space is formed by etching a part of the substrate, the diaphragm made of the thin film shape memory alloy and the second thin film is bent and deformed by the residual compressive stress of the second thin film. When a thin film shape memory alloy is heated, it tends to change to a flat state due to the shape memory alloy. At this time,
The volume of the liquid chamber is reduced and the recording liquid is ejected. During cooling, the bending deformation occurs due to the residual compressive stress of the second thin film. At this time, the recording liquid is refilled. By repeating such a process, continuous ejection of the recording liquid is performed.

According to the present invention, a diaphragm having a simple structure and comprising a thin film shape memory alloy and a second thin film is manufactured by a semiconductor thin film manufacturing process and a substrate etching process, and the diaphragm is manufactured by such a semiconductor thin film manufacturing process. (2) The displacement of the diaphragm required for jetting the recording liquid can be easily obtained by using the residual compressive stress of the thin film, so that mass productivity is improved, and the residual stress of the second thin film is changed to change the magnitude of the residual stress. Since the amount can be easily adjusted and the amount of displacement can be increased, the area of the diaphragm is reduced. Therefore, the size of the head can be reduced, and high resolution can be achieved by increasing the density of the nozzles. Further, the second thin film adjusts the direction of bending deformation and contributes to diversification of the structure of the recording liquid ejecting apparatus.

In the present invention, since a thin film shape memory alloy is used, the power consumption during heating is greatly reduced, and the cooling time is greatly shortened. Further, when the thin film shape memory alloy returns to the state of bending deformation due to the residual compressive stress of the second thin film after the ejection of the recording liquid, the restoring force is strong and no residual vibration is generated.
Stable ejection of the recording liquid can be performed. Therefore, the operating frequency is improved, that is, the printing speed is improved.

[0017]

FIG. 3 is an exploded perspective view of an ejection device according to one embodiment of the present invention, and FIG. 4 is a perspective view showing a flow of a recording liquid according to one embodiment of the present invention. In the ejecting apparatus of the present invention, in order to increase the resolution, a large number of nozzles 19 for ejecting the recording liquid 20 are arranged vertically and horizontally, and the diaphragm 12 for substantially ejecting the recording liquid 20 is paired with each nozzle 19. Corresponds to 1. That is, a large number of spaces 11 penetrating in the vertical direction are formed before and after the substrate 10, and a large number of vibration plates 12 which are connected to the upper portion of the substrate 10 and close each space 11 are provided. The vibration plate 12 vibrates according to the temperature, and ejects the recording liquid 20 by the generated force at this time. Such a diaphragm 12 is composed of a thin film memory shape alloy 12a and a second thin film 12b, and in particular, the second thin film 12b is composed of a material capable of adjusting the amount of deformation and restoring force of the diaphragm 12, The operating frequency is increased by increasing the bending deformation speed (restoring force).

Further, there is provided a flow path plate 13 for covering the upper part of the substrate 10, and a liquid chamber 14 for storing the recording liquid 20 is formed in the flow path plate 13 immediately above each of the vibration plates 12. In addition, the flow path plate 1
A main flow path 15 through which the recording liquid 20 flows is provided at the center of 3, and the main flow path 15 and the corresponding liquid chamber 14 communicate with each other through a flow path 16. Further, on one side of the substrate 10, there is provided a liquid inlet 17 communicating with the main flow path 15 on one side of the flow path plate 13, and the recording liquid 20 is supplied to the main flow path 15 side.

Further, a nozzle plate 18 is provided to be connected to the upper part of the flow path plate 13.
A number of nozzles 19 corresponding to each liquid chamber 14 formed in 3 are formed. Further, each nozzle 19 corresponds to the diaphragm 12 exposed to the liquid chamber 14 side. When the vibration plate 12 vibrates, the pressure of the liquid chamber 14 changes, and the recording liquid 20 drops in a liquid state. The ink is ejected onto the sheet via the nozzle 19.

Thin film shape memory alloy 1 constituting diaphragm 12
2a undergoes a continuous phase change due to a temperature change. In this process, vibration occurs, and the recording liquid 20 is ejected through each nozzle 19 in a liquid state. In addition, the thin film shape memory alloy 12a
As shown in FIG. 5A, heating is performed by the power supply unit 21. That is, when a current flows from the electrodes 21a coupled to both ends of the thin film shape memory alloy 12a, the thin film shape memory alloy 1
2a is heated by self-resistance, the temperature rises, and it tends to become flat. Further, when the current of the power supply unit 21 is cut off, the thin film shape memory alloy 12a cools naturally and the diaphragm 12
Is restored to the original expanded state by the second thin film 12b.

As shown in FIG. 5B, a heater 21b for heating by a current from the power supply unit 21 is provided on one side surface of the second thin film 12b, and the thin film shape memory alloy 1 is provided.
2a can be heated. Then, as shown in FIG. 5C, another heat radiation film 12c can be provided on the bottom surface of the second thin film 12b in order to increase the cooling rate of the diaphragm 12. The heat dissipating film 12c cools and restores the heated diaphragm 12 in a short time, and increases the operating frequency of the diaphragm 12. Such a heat radiating film 12c is made of nickel having excellent heat radiating properties, and has a thickness of about 0.5 μm or more.
3 μm. The thin film shape memory alloy 12a constituting the diaphragm 12 is mainly composed of titanium and nickel, and has a thickness of about 0.1 μm to 5 μm. The second thin film 12a is made of thermal silicon oxide, polysilicon, or the like, and has a thickness of about 0.1 μm to 3 μm.

FIGS. 6A to 6C are cross-sectional views of the injection apparatus according to the embodiment of the present invention. Silicon is used as the material of the substrate 10. FIG. In the initial state in which the diaphragm 12 is plumply deformed on the opposite side of the nozzle 19, the thin film shape memory alloy 12
When a is heated to a temperature equal to or higher than the set temperature, the diaphragm 12 tends to become flat. At this time, the internal pressure of the liquid chamber 14 increases, and the recording liquid 20 is ejected through the nozzle 19 by being compressed.

When the temperature of the thin film shape memory alloy 12a falls below the set temperature, the diaphragm 12 is restored to its original expanded state by the residual compressive stress of the second thin film 12b.
At this time, after the internal pressure of the liquid chamber 14 decreases and the recording liquid 20 flows into the liquid chamber 14 due to the capillary action and the suction force of the nozzle 19, the above process is continuously repeated, and the recording liquid drops. Inject in the state of. Further, when the diaphragm 12 is deformed to a swollen state, the restoring force of the diaphragm 12 is strengthened by the residual compressive stress of the second thin film 12b, and the operating frequency is increased. That is, the second thin film 12b can restore in a short time by increasing the restoring force of the diaphragm 12. Since the recording liquid is replenished quickly and the recording liquid can be ejected immediately, the operation speed of the printer head is improved.

FIG. 8 is a process diagram showing a method for manufacturing a diaphragm according to the present invention, and FIG. 9 is a block diagram showing a method for manufacturing a diaphragm according to the present invention, which uses a semiconductor manufacturing process and a substrate etching process. . A second thin film 12b is formed on a substrate 10 made of a material such as silicon, glass, metal, or polymer.
Is formed by a semiconductor thin film manufacturing process to maintain a predetermined amount of residual compressive stress. The method includes a step 101 of forming the diaphragm 12 by depositing the thin film shape memory alloy 12a on the second thin film 12b. At this time, a sputtering method is mainly used as an evaporation method. The method also includes a step 102 of heat treating the thin film shape memory alloy 12a at a constant temperature for a predetermined time to crystallize the thin film shape memory alloy 12a so that the flat state is stored as a matrix. Then, the thin film shape memory alloy 12a is set to a martensite finish temperature (Mf) of about 4
Step 10 of cooling to 0 ° C. to 70 ° C. to martensite
3 is provided.

Further, the space immediately below the diaphragm 12 is etched by silicon to form a space 11 in the substrate 10.
2 is exposed to the outside, and the diaphragm 12 is bent downward (or upward) by the residual stress of the second thin film 12b while the diaphragm 12 is exposed to the outside, as shown in FIG. Is provided. The second thin film 12b is a process of forming using a semiconductor manufacturing process, and the magnitude of the residual stress can be adjusted by the deposition conditions and the material. In particular, the second thin film 12b is formed on the upper side of the thin film shape memory alloy 12a. Alternatively, the bending direction of the diaphragm 12 is determined by forming it on the lower side.

In the course of such bending deformation, the thin film shape memory alloy 12a maintains martensite. Also,
When the thin film shape memory alloy 12a is heated to a set temperature, that is, about 50 ° C. to 90 ° C., which is the parent phase end temperature (Af), FIG.
Step 107 in which the recording liquid 20 is ejected after being transformed into a flat plate shape as shown in FIG. And the thin film shape memory alloy 1
When 2a cools and becomes martensite, the second thin film 12b
Is bent and deformed by the residual compressive stress of
0, and the above steps 107 and 108 are repeated according to the temperature change of the thin film shape memory alloy 12a, and the recording liquid 20 is ejected in the form of droplets and printed.
9 is provided.

The thin film shape memory alloy 12a of the present invention
Is flattened in the parent phase during heating and bends and deforms in martensite during cooling due to a temperature difference. Therefore, as the temperature difference is reduced, the frequency (operating frequency) of the thin film 12 increases. Therefore, copper can be added to the alloy of titanium and nickel to reduce the temperature difference. As described above, the shape memory alloy using titanium, nickel, and copper can increase the frequency, that is, the operating frequency of the thin film shape memory alloy 12a by reducing the temperature difference of the phase change, thereby improving the printing speed.

Interpreting the possibility of producing a droplet using the thin film memory shape alloy of the present invention configured as described above is as follows.

The energy density generated by the thin film shape memory alloy 12a is at most 10 × 10 ⁶ J / m ³ , and the size of the thin film shape memory alloy 12a exposed in the space 11 is 2
In the case of 00 μm × 200 μm × 1 μm, assuming that the diameter of the generated droplet is 60 μm, it is possible to calculate the propriety of ejection from the thin film as follows. U = U _S + U _K U _S = πR ² γ

(Equation 1) U = energy required to generate a desired droplet of the recording liquid U _S = surface energy of the recording liquid U _K = kinetic energy of the recording liquid R = diameter of the droplet V = velocity of the recording liquid ρ = of the recording liquid Density (1000 kg / m ³ ) γ = Surface tension of recording liquid (0.073 N / m)

Assuming that the speed of the desired droplet is 10 m / sec, the required energy (U) is: U = 2.06 × 10 ⁻¹⁰ + 7.07 × 10 ⁻¹⁰ = 9.13
× 10 ⁻¹⁰ J.

The maximum energy generated by the thin-film shape memory alloy (12a) is as follows: W _max = W _v · V W _max = (10 × 10 ⁸ ) · (200 × 200 × 1) = 4 × 10 ^-7 J .

When the diameter of the droplet is 100 μm, the required energy is U = 3.85 × 10 ⁻⁹ J.

Therefore, since W _max >> U, a droplet having a desired size can be obtained. That is, since the thin film shape memory alloy 12a has a very large generating force, it is possible to easily obtain a desired recording liquid droplet.

The displacement of the heating time, the consumed energy and the residual compressive stress according to the embodiment of the present invention are analyzed as follows. A current is caused to flow through the thin film shape memory alloy 12a, so that heat is generated by resistance, and the heat causes a phase change to occur. The required heating time and energy consumption are as follows. Material of thin film shape memory alloy = TiNi Length of thin film shape memory alloy (l) = 400 µm Density of thin film shape memory alloy (ρ _s ) = 6450 kg / m ³ Temperature change (ΔT) = 70-25 = 45 ° C Heat capacity ( Specific heat) (C _p ) = 230 J / kg ° C. Specific resistance of thin film shape memory alloy (ρ) = 80 μ · cm Current (I) = 1.0 A Thin film shape memory alloy width (w) = 300 μm height (t) = 1.0μm heating time (t _h)

(Equation 2) Resistance (R) of thin film shape memory alloy = ρ (1 / w · t) = 1.1Ω Power consumption (I ² R) = 1.1 watt The energy required to generate a droplet is heating time × power consumption = It becomes 8.1 μJ.

Therefore, the energy required for ejecting the recording liquid 20 to generate liquid droplets is about 8.1 μJ, which consumes less energy than the conventional heating method of 20 μJ.

FIG. 10 is a graph showing the heating time and temperature of the thin film shape memory alloy of the present invention. However, the thickness of the thin film shape memory alloy 12a is 1 μm.
m and the ambient temperature is 25 ° C.

[Table 1]

When the ambient temperature is 25 ° C., after heating to 70 ° C. to change into the parent phase, the time to cool to 30 ° C. is about 2 hours.
It is about 00 μsec, which is about 5 kHz when converted to a frequency. Therefore, the operating frequency of the printer head is about 5 kHz. However, since the temperature at which the deformation is completely completed (the martensite end temperature) is about 45 ° C., there is no need to wait until the temperature drops to 30 ° C., and before that, the recording liquid 20 can be reheated and the recording liquid 20 can be continuously jetted. , 5
The operating frequency can be increased to more than kHz. The higher the operating frequency, the higher the printing speed.

The displacement and restoring force due to the residual compressive stress of the thin film shape memory alloy and itself are analyzed as follows with reference to FIG. When a = b a = 200 μm Material of thin film shape memory alloy = TiNi Young's modulus (E _m ) of thin film shape memory alloy = 30 GPa Residual compressive stress existing in thin film shape memory alloy = 30 MPa Poisson's ratio (ν) = 0. 3 of thin film shape memory alloy exposed to the space portion 11 length = a thin film shape memory alloy thickness = h _m space 11 in the exposed width of the thin-film shape memory alloy = b thin shape memory alloy of the critical stress (S _cr)

(Equation 3) S _cr = 3.6 MPa Center displacement (δ _m ) of thin film shape memory alloy:

(Equation 4) δ _s = 6.2 μm

The maximum energy generated by the thin film shape memory alloy is W _max = W _v · V. ( _Wv : energy that can be exhibited per unit volume of the thin film shape memory alloy J / m ³ , V: volume of the thin film shape memory alloy) W _max = (10 × 10 ⁶ ) · (200 × 200 × 1) = 4
× 10 ^-7 J

Total energy (U _m ) generated by buckling of the thin film shape memory alloy during cooling

(Equation 5) = 2.8 × 10 ^-10 J

After the recording liquid 20 is jetted, the total energy generated when the thin film shape memory alloy buckles is converted into a restoring force (P) that causes bending deformation of the thin film shape memory alloy. The restoring force is as follows. U _m = P · ΔV Volume change (ΔV) = (δ _s · α ₂ ) /4=6.2×10 ⁻¹⁴ m ³ Restoring force (P) = 4.5 kPa

Assuming that half of the total volume change caused by the buckling of the thin film shape memory alloy was injected, 39 μm
To form droplets. The amount of displacement with respect to the thickness and size of the thin film shape memory alloy is as shown in the table below, and the unit is μm.

[Table 2]

If the thin film shape memory alloy 12a constituting the diaphragm 12 has no residual compressive stress, the second thin film 12b
The displacement amount and the restoring force due to the residual compressive stress are obtained as follows. (See FIG. 11) When a = b, a = 200 μm Material of thin film shape memory alloy = TiNi Material of second thin film = Young's modulus (E _m ) of thermally oxidized SiO ₂ thin film shape memory alloy = 30 GPa Young's modulus (E _s ) = 70 GPa Residual compressive stress (S) acting on the second thin film = 300 MPa Poisson's ratio (ν) = 0.3 Length of diaphragm 12 exposed to space 11 = a To space 11 Exposed width of diaphragm 12 = b Thickness of thin film shape memory alloy (h _m ) = 1 μm Thickness of second thin film (h _s ) = 1 μm Critical stress (S _cr ) of second thin film

(Equation 6) S _cr = 8.4 MPa Center displacement (δ _s ) of the second thin film when not bonded to the thin film shape memory alloy

(Equation 7) δ _s = 13.5 μm

The bending energy (U _b ) generated by the residual compressive stress of the second thin film

(Equation 8) = 2.9 × 10 ^-19 J

The bending energy of the second thin film is stored as the bending energy of the diaphragm 12 composed of the thin film shape memory alloy and the second thin film.

(Equation 9) D _s = 6.5 × 10 ⁻⁹ N / m D _m = 2.7 × 10 ⁻⁹ N / m

Using the above equation, the displacement (δ) of the diaphragm 12
Is obtained, δ = 11.4 μm.

The energy lost in the second thin film when the recording liquid is jetted by heating the thin film shape memory alloy is the bending energy generated by the residual compressive stress of the second thin film. Bending energy (U _s ) = 2.9 × 10 ⁻⁹ J Maximum energy (W) generated by the thin film shape memory alloy
_max ) = _Wv · V ( _Wv : energy J / m ³ that can be exhibited per unit volume of the thin film shape memory alloy, V: volume of the thin film shape memory alloy) W _max = (10 × 10 ⁶⁾ ) · (200 × 200 × 1) = 4
× 10 ^-7 J

The ratio (U _s / W _max ) of the energy consumed by the second thin film to the maximum energy that can be calculated by the thin film shape memory alloy is 0.73%. Therefore, when ejecting the recording liquid, the effect of energy loss due to the second thin film can be ignored.

The total energy (U _s ) generated when the second thin film buckles

(Equation 10)

After the ejection of the recording liquid, the total energy (U _s ) generated when the second thin film buckles is changed into the restoring force (P) of the diaphragm 12. The restoring force is as follows. U _s = P · ΔV Volume change (ΔV) = (δ _s · α) /4=1.4×10 ⁻¹³ m ³ Restoring force (P) = 107.1 kPa

The change in the overall volume due to the deformation of the diaphragm 12 is 1
Assuming a jet of / 2, the droplet diameter is 51 μm.

Comparing the diaphragm composed only of the thin film shape memory alloy with the diaphragm composed of the thin film shape memory alloy and the second thin film, the displacement increased about twice from 6.2 μm to 11.4 μm. , Restoring force from 4.5 kPa to 107.1 k
Pa increased about 20 times or more. Therefore, when the second thin film is used, a desired displacement can be easily obtained, and the restoring force can be increased.

The displacement of the diaphragm 12 composed of the thin film shape memory alloy and the second thin film is as follows, and its unit is μm.

[Table 3]

FIG. 12 is a sectional view of an injection device according to another embodiment of the present invention, and the present invention will be described using the same reference numerals for the same components as those in FIG. In another embodiment of the present invention, the flow path plate 13 and the nozzle plate 18
This is an extract of the bonding state of one thin film. Space 1 penetrating vertically through substrate 10
1 is formed and provided with a diaphragm 12 which is coupled to the upper part of the substrate 10 and covers the space 11. The diaphragm 12 vibrates due to a temperature change of the thin film shape memory alloy 12a, and ejects the recording liquid 20 by the generated force generated at this time. Further, the second thin film 12b constituting the diaphragm 12 increases the bending deformation speed (restoring force) of the diaphragm 12 to increase the operating frequency.

Further, a flow path plate 13 covering the lower portion of the substrate 10 is provided.
Is formed in the liquid chamber 14. In addition, a nozzle plate 18 is provided below the flow path plate 13, and a nozzle 19 corresponding to the liquid chamber 14 formed in the flow path plate 13 is formed on the nozzle plate 18. The nozzle 19 corresponds to the diaphragm 12 exposed on the liquid chamber 14 side. When the diaphragm 12 is deformed, the pressure of the liquid chamber 14 changes, and the recording liquid 20 is ejected onto the sheet via the nozzle 19 in a state of liquid droplets.

In another embodiment of the present invention configured as described above, the thin film shape memory alloy 12a
Is formed, the second thin film 12b becomes thin film shape memory alloy 12
Vapor deposition on top of a. Then, the substrate 1 is etched.
When the space 11 is formed at the lower part of the diaphragm 12, the diaphragm 12
The thin film 12b is bent and deformed by the residual compressive stress. When the thin film shape memory alloy 12a is heated in such a state of bending deformation, the vibration plate 12 is deformed into a flat plate state, and then cooled to be bent and deformed to an initial state. Further, in the process of bending deformation of the diaphragm 12, the operating frequency is increased because the restoring force is strengthened by the residual compressive stress of the second thin film 12b.

FIG. 13 is a cross-sectional view of an injection device according to still another embodiment of the present invention, and the same components as those in the embodiment of the present invention will be described using the same reference numerals. In the present embodiment, the diaphragm 12 is formed below the substrate 10, and the flow path plate 13 and the nozzle plate 1 are formed above the substrate 10.
8 are formed respectively. That is, in an initial state where the thin film shape memory alloy 12a is not heated, the diaphragm 12 is in a state of protruding into the space 11, but becomes flat when heated. Therefore, when the vibration plate 12 is heated, the recording liquid 20 becomes flattened and the recording liquid 20 is replenished into the liquid chamber 14, and when cooled, the recording liquid 20 is ejected because it bends and deforms and the pressure inside the liquid chamber 14 increases.

FIG. 14 is a cross-sectional view of an injection device according to still another embodiment of the present invention, and the same components as those of the embodiment of the present invention will be described using the same reference numerals. In the present embodiment, a plurality of second thin films 12b are used, and the second thin films can be made of different materials.
FIG. 14A shows that 2 is formed on the lower surface of the thin film shape memory alloy 12a.
FIG. 14B shows the second thin film 12b formed on the upper and lower surfaces of the thin film shape memory alloy 12a.
2b. With this configuration, the restoring force of the diaphragm 12 can be further increased, and a desired displacement can be more easily obtained. Further, the durability of the diaphragm 12 is increased, so that reliability is ensured.

[0059]

As described above, according to the present invention,
When the temperature of the thin film shape memory alloy changes, the diaphragm vibrates, so that the recording liquid is ejected. In addition, since it is bonded to the second thin film having a residual compressive stress, when it is cooled and restored to the initial state, the restoring force is increased by the residual compressive stress, and the operating frequency is increased. Further, since the vibration plate has a large displacement amount, each space formed in the substrate and each liquid chamber formed in the flow path plate can be made small, so that the overall size of the printer head is reduced and downsized. Therefore, high resolution can be achieved by increasing the density of the nozzles.

Further, since the strength of the diaphragm is increased by the second thin film, there is little possibility that the diaphragm is damaged by an external impact. Further, since the generated force is large, the force for pushing out the recording liquid is increased, the clogging of the nozzle is reduced, the reliability is improved, and the size of the droplet of the recording liquid can be sufficiently reduced. This is effective for realizing high image quality. The driving voltage is 10
Since it is less than volts, the design and manufacture of the drive circuit is easy, and the diaphragm can be easily manufactured using the existing semiconductor process and etching process, so that mass productivity is improved,
There are effects such as a simple structure.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a conventional heating type injection device.

FIG. 2 is a sectional view of a conventional piezoelectric element type injection device.

FIG. 3 is an exploded perspective view of an injection device according to an embodiment of the present invention.

FIG. 4 is a perspective view illustrating a flow of a recording liquid according to an embodiment of the present invention.

FIGS. 5A, 5B, and 5C are front sectional views of an injection device according to an embodiment of the present invention.

FIGS. 6A, 6B, and 6C are cross-sectional views illustrating an operation process of the injection device according to the embodiment of the present invention.

FIG. 7 is a graph showing a phase change of the thin film shape memory alloy of the present invention.

FIG. 8 is a process chart showing a method for manufacturing a diaphragm according to the present invention.

FIG. 9 is a block diagram illustrating a method for manufacturing a diaphragm according to the present invention.

FIG. 10 is a graph showing the relationship between the heating time and the temperature of the thin film of the present invention.

FIG. 11 is a sectional view showing the size of the diaphragm of the present invention.

12 (a), (b) and (c) are cross-sectional views of an injection device showing an operation process according to another embodiment of the present invention.

FIGS. 13 (a), (b), (c) and (d) are cross-sectional views showing an injection device according to still another embodiment of the present invention.

FIGS. 14A and 14B are cross-sectional views showing an injection device according to still another embodiment of the present invention.

[Explanation of symbols]

 a1, b1 Chamber a2, b2 Injection port a3 Resistance b3 Piezoelectric element 11 Space section 12 Vibration plate 12a Thin film shape memory alloy 12b Second thin film 12c Heat dissipation film 13 Flow path plate 14 Liquid chamber 15 Main flow path 16 Flow path 17 Liquid injection port 18 Nozzle plate 19 Nozzle 20 Recording liquid 21 Power supply 21a Electrode 21b Heater

Claims (19)

[Claims] 1. A thin film shape memory alloy (12a) made of a shape memory alloy material whose shape changes according to a temperature change, and at least one or more sheets connected to the thin film shape memory alloy (12a) to adjust the shape change amount. A diaphragm (12) comprising a second thin film (12b); a power supply (21) for generating a temperature change of the thin film shape memory alloy (12a); and one side of the thin film shape memory alloy (12a) Installed in
A liquid chamber (14) for storing the recording liquid (20) is formed, and a flow path (16) is formed so that the recording liquid (20) flows into one side of a wall surrounding the liquid chamber (14). ) Is formed on the flow path plate (13), and the recording liquid (20) is ejected in the form of droplets when the thin film (12) changes shape. A nozzle plate (18) formed with a nozzle (19) having an area smaller than the area of the liquid chamber (14) of the flow path plate (13). 2. A recording liquid ejecting apparatus for a printer head according to claim 1, wherein said thin film shape memory alloy (12a) is a shape memory alloy containing titanium and nickel as main components. 3. The thin film shape memory alloy (12a) is a shape memory alloy to which copper is further added in order to reduce a phase change temperature difference and increase an operation frequency. Recording liquid ejection device for printer head. 4. The thin film shape memory alloy (12a)
2. The apparatus according to claim 1, wherein the apparatus has a thickness of 0.3 [mu] m to 5 [mu] m. 5. The device according to claim 1, wherein the second thin film has a thickness of about 0.1 μm to 3 μm.
A recording liquid ejecting apparatus for a printer head according to claim 1. 6. The apparatus according to claim 1, wherein the second thin film includes thermal silicon oxide. 7. The apparatus according to claim 1, wherein the second thin film includes polysilicon. 8. The power supply unit (21) includes electrodes (21a) coupled to both ends of the thin film shape memory alloy (12a) so that heat is generated by the self-resistance of the thin film shape memory alloy (12a). 2. A recording liquid ejecting apparatus for a printer head according to claim 1, wherein: 9. The heater (2) formed on one side surface of the thin film shape memory alloy (12a) and heated by a current from the power supply unit (21).
The recording liquid ejecting apparatus for a printer head according to claim 1, further comprising 1b). 10. A heat dissipating film (12c) formed on one side surface of the diaphragm (12) to dissipate the heat when the thin film shape memory alloy (12a) is heated and then cooled.
The recording liquid ejecting apparatus for a printer head according to claim 1, further comprising: 11. The heat radiation film (12c) has a thickness of about 0.5 μm to 3 μm.
0. A recording liquid ejecting apparatus for a printer head according to 0. 12. The recording liquid ejecting apparatus for a printer head according to claim 10, wherein said heat radiating film (12c) comprises nickel having good thermal conductivity. 13. Placed below said diaphragm (12),
2. A recording liquid ejecting apparatus for a printer head according to claim 1, further comprising a substrate (10) having a space (11) in which the thin film shape memory alloy (12) can change its shape. 14. The vibration plate (12) is provided in the space (1).
14. The printer according to claim 13, wherein the area exposed to 1) and substantially changing its shape has a width (b) of 100 μm to 500 μm and a length (a) of 100 μm to 300 μm. Recording liquid ejecting device for head. 15. The apparatus according to claim 13, wherein the substrate comprises a single-crystal silicon material. 16. The vibrating plate (12) takes the form of a flat plate when the thin film shape memory alloy (12a) is heated to a parent phase end temperature and changed to a parent phase, and cooled to a martensite termination temperature to form a martensite. When the site changes, the second thin film (1
2. The recording liquid ejecting apparatus for a printer head according to claim 1, wherein the recording liquid is ejected by the residual compressive stress of 2b). 17. The thin-film shape memory alloy (12a) having a parent phase termination temperature of about 50 ° C. to 90 ° C., and the martensite termination temperature of about 40 ° C. to 70 ° C. A recording liquid ejecting apparatus for a printer head according to claim 1. 18. The thin film shape memory alloy (12a)
The time from heating to the mother phase to cooling to martensite is about 200 μsec or less, and the operating frequency is 5 kHz.
17. The recording liquid ejecting apparatus for a printer head according to claim 16, wherein z is not less than z. 19. A step (100) of forming a second thin film (12b) on the substrate (10) to maintain a residual compressive stress; and forming a thin film shape memory alloy (12) on the second thin film (12b).
a) evaporating to form a diaphragm (12) (10)
1) heat treating the thin film shape memory alloy (12a) to store a flat plate as a matrix (102); and cooling the thin film shape memory alloy (12a) to martensite (103). (104) etching a part of the substrate (10) to expose a part of the diaphragm (12); and exposing a part of the diaphragm (12) to the second thin film (12).
Step b) of bending deformation due to residual compressive stress in b)
Heating the thin film shape memory alloy (12a) into a flat plate shape and injecting a recording liquid (20); and cooling the thin film shape memory alloy (12a) to become martensite. Refilling the recording liquid (20) into the liquid chamber (14) by bending and deforming the second thin film (12b) due to residual compressive stress; and temperature of the thin film shape memory alloy (12a). By change
The steps (106) and (107) are repeated, and the recording liquid (20) is ejected in the form of droplets to perform printing (1).
08), wherein the recording liquid ejection method for a printer head is provided.