JPH1052071A - Antiferroelectric-ferroelectric phase transition film actuator and ink-jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator that has excellent manufacturability, consumes less power, produces large distortion (amount of displacement) and force, and is excellent in phase transition, and an ink-jet printer head of high density and integration using the actuator, by using an antiferroelectric - ferroelectric phase transition material for the actuator. SOLUTION: A drive part comprising a combination of a first electrode film 4, an antiferroelectric - ferroelectric phase transition film 5 and a second electrode film 6, is formed on a ceramic board 3 to constitute an antiferroelectric - ferroelectric phase transition actuator. This antiferroelectric - ferroelectric phase transition actuator is used for an ink-jet printer to obtain a high-speed ink-jet printer head that enables high density and integration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antiferroelectric-ferroelectric phase transition actuator having an excellent volume change rate and a structure which can be provided by a simple manufacturing method. It is applicable to.

[0002]

2. Description of the Related Art In recent years, as one of mechanisms for increasing the pressure in a pressurizing chamber provided inside a base of an actuator,
A piezoelectric / electrostrictive actuator composed of a piezoelectric / electrostrictive element and a substrate configured to change the volume of the pressurizing chamber by displacement of a piezoelectric / electrostrictive element provided on a substrate functioning as a working plate such as a diaphragm is known. This is disclosed, for example, in JP-A-3-128681 as a piezoelectric / electrostrictive film type actuator. Such a piezoelectric / electrostrictive film type actuator is used, for example, as a print head used in an ink jet printer, and is supplied with ink, and the pressure inside the pressurized chamber is changed by the displacement of the piezoelectric / electrostrictive film type actuator. Ink particles (droplets) from the nozzle holes communicating with the pressure chamber
And print it out. Since such a piezoelectric / electrostrictive film type actuator does not have a structure bonded with an adhesive, the operation reliability is high, a large displacement can be obtained at a relatively low driving voltage, and the response speed is high. Since it is fast and has a large power, it is suitable for high density and high integration of ink jet.

However, in order to further increase the density and the volume of the printer head, when the width of the ink cavity becomes narrower, it is necessary to obtain the necessary ink ejection performance. An actuator constituent material having a large displacement and a large generating force has been desired. Further, the actuator having such excellent performance is advantageous not only for the above-described ink jet head but also for applications to micro pumps, speakers, sensors, vibrators, filters, and the like.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has excellent manufacturability and low power consumption by using an antiferroelectric-ferroelectric phase transition material for an actuator. The present invention provides an actuator having a large displacement (displacement amount) and a large generating force and excellent phase transition characteristics, and an ink jet printer head using the actuator to realize high density and high integration. Should be a task to be done.

[0005]

According to a first aspect of the present invention, there is provided a combination of a first electrode film, an antiferroelectric-ferroelectric phase transition film, and a second electrode film on at least one surface of a ceramic substrate. At least one of the anti-ferroelectric-ferroelectric phase transition driving units has a structure in which those films are sequentially laminated and formed in a layered manner. By using this, an antiferroelectric-ferroelectric phase transition film can be easily formed by the film forming method with excellent mass productivity, the maximum stress is larger than that of the piezoelectric / strain film, and the volume change rate is one digit or more. Because of its large size, the actuator can be made smaller, more highly integrated, and lower in power consumption.

According to a second aspect of the present invention, in the first aspect, the antiferroelectric-ferroelectric phase transition film is made of Pb [(Zr _x Sn _{1 -x} ).
_1-y Ti _y ] O ₃ (where x and y are 0.3 ≦ x ≦ 1, 0 ≦
y is used in the range of y ≦ 0.2), by using an antiferroelectric-ferroelectric phase change film type actuator characterized by exhibiting antiferroelectricity at room temperature. This eliminates the need for heating during use, thereby reducing power consumption.

According to a third aspect of the present invention, in the first aspect, the antiferroelectric-ferroelectric phase transition film is formed of Pb _{1 -z} La _z [(Zr _x S
n _1-x ) _1-y Ti _y ] _{1-1 / 4z} O ₃ (where x, y, z are 0.3
≦ x ≦ 1, 0 ≦ y ≦ 0.2, 0 ≦ z ≦ 0.04). By using a dielectric phase change film type actuator, it exhibits antiferroelectricity at room temperature, does not require heating at the time of use, can achieve low power consumption, and has the antiferroelectric-ferroelectric phase change film. The sintering characteristics can be improved.

According to a fourth aspect of the present invention, in the first aspect, the antiferroelectric-ferroelectric phase transition film is formed of Pb _{1-1 / 2z} Nb _z [(Zr
_x Sn _1-x ) _1-y Ti _y ] _1-z O ₃ (where x, y, z are 0.3
≦ x ≦ 0.8, 0.04 ≦ y ≦ 0.2, 0 ≦ z ≦ 0.04). By using a phase change film type actuator, it exhibits antiferroelectricity at the room temperature, does not require heating during use, can achieve low power consumption, and has the antiferroelectric-ferroelectric phase change film. The sintering characteristics can be improved.

According to a fifth aspect of the present invention, there is provided an ink-jet printer head having an anti-ferroelectric-ferroelectric phase change film type actuator, which is capable of achieving high density and high integration and high speed. It is something that can be done.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, in order to facilitate understanding of the present invention, a piezoelectric material and an electrostrictive material used in a piezoelectric / electrostrictive element described as an example of the prior art and an antiferroelectric material according to the present invention will be described. The difference from the ferroelectric phase change material will be described with reference to the attached drawings. FIG. 1 is a diagram showing an electric field-polarization relationship for explaining characteristics of a piezoelectric material. FIG. 2 is a diagram showing the relationship between electric field and strain (displacement) for explaining the characteristics of the piezoelectric material. FIG. 3 is a diagram showing an electric field-polarization relationship for explaining characteristics of the electrostrictive material. FIG. 4 is a diagram showing a relationship between electric field and strain (displacement) for explaining characteristics of the electrostrictive material. FIG. 5 is a diagram illustrating an electric field-polarization relationship for explaining characteristics of an antiferroelectric-ferroelectric phase transition material. FIG. 6 is a view showing the relationship between electric field and strain (displacement) for explaining the characteristics of the antiferroelectric-ferroelectric phase transition material.

[0011] The materials that generate elastic deformation (strain) by applying an electric field include a piezoelectric material using the inverse piezoelectric effect, an electrostrictive material using the electrostrictive effect, and an electric-field-induced forced phase transition of an antiferroelectric material. There is a phase change material utilizing the following (hereinafter simply referred to as phase change).

More specifically, the piezoelectric material is mainly composed of lead zirconate titanate (PZT) -based material, lead nickel niobate (PNN) -based material, and lead manganese niobate. Ingredients, lead antimony stannate as the main component, lead titanate as the main component, and lanthanum, barium, niobium, zinc, cerium, cadmium, chromium, cobalt, strontium, antimony A material containing an oxide such as iron, yttrium, tantalum, tungsten, nickel, manganese and other compounds as additives, for example, the PZT so as to be a lead lanthanum titanate zirconate (PLZT) -based material. There is a material in which a predetermined additive as described above is appropriately added to a material whose main component is a system. The inverse piezoelectric effect of these piezoelectric materials is shown in FIG. Field (E) as shown - shows the hysteresis curve in the polarization (P) relationship, and FIG. 2
As shown in (1), in low electric field strength without polarization reversal or single electric field (applied electric field in the same direction as polarization) drive, the strain (△ l / l) is proportional to the applied voltage.

The electrostrictive material includes a material mainly composed of lead magnesium niobate (PMN), a material mainly composed of lead zinc niobate, and lanthanum, barium, niobium, zinc, cerium. , Cadmium, chrome,
Materials containing oxides such as cobalt, strontium, antimony, iron, yttrium, tantalum, tungsten, nickel, and manganese and other compounds as additives, for example, PZT-based materials to become PLZT-based materials The electrostriction effect does not show a hysteresis curve in the electric field (E) -polarization (P) relationship as shown in FIG. As shown in FIG. 4, in the electric field (E) -strain (△ l / l) characteristic, the strain is proportional to the square of the applied voltage.

On the other hand, the phase change material is, for example, an antiferroelectric material mainly composed of lead zirconate (PbZrO ₃ ), that is, lead zirconate (PbZrO ₃ ), lead zirconate stannate (PZS), zirconate In addition to lead titanate (PZT), lead zirconate hafnate, lead lanthanum zirconate titanate (PLZT), ceramics having a composition of niobium, lanthanum, bismuth, titanium, tantalum, etc. as a dopant can be mentioned. The electric field (E) -polarization (P) relationship in the electric field induced forced phase transition phenomenon of FIG. 5 shows a double hysteresis curve as shown in FIG. 5, and the electric field (E) -strain (△ l / l) characteristic is While the piezoelectric material and the electrostrictive material generate strain continuously with respect to the voltage, FIG.
As shown in (1), the distortion is generated discontinuously.

As shown in Table 1, the distortion of such a phase change material is about three to four times larger than that of a piezoelectric material. Also, the strain of the electrostrictive material reported to date is about 1/3 of that of the piezoelectric material, and the giant strain of 9 to 12 times that of the electrostrictive material is generated as compared with the phase change material. Become. On the other hand, the maximum generated stress of the phase change material estimated from the amount of displacement under the compressive stress reaches 1.8 to 2.3 times that of the piezoelectric material or the electrostrictive material. Such a large generated stress and the generation of a large distortion are suitable for realizing a powerful voltage-pressure conversion element as an actuator. In particular, when this element is used in an ink jet printer head, the ink ejection force It has the advantage of being stiff.

In other words, the high integration of the printer head reduces the width of the ink cavity, and provides a sufficiently effective actuator when a force is required for the voltage-pressure conversion element.

[0017]

[Table 1]

The relative permittivity of the piezoelectric material is 3000 to 5
000, that of the electrostrictive material is as large as 10,000 to 20,000, whereas that of the phase change material is 250 to 500, which is one order of magnitude lower. This means that power energy (simply power consumption) related to charge and discharge of electric charges during element driving can be reduced.

An embodiment of an antiferroelectric-ferroelectric phase transition actuator according to the present invention will be described below with reference to the accompanying drawings. (Embodiment 1) FIG. 7 is a cross-sectional view for explaining the structure of an embodiment of an antiferroelectric-ferroelectric phase transition actuator according to the present invention. In FIG. 7, 1 is a spacer plate, 2 is a pressure chamber,
3 is a ceramic substrate, 4 is a lower electrode film, 5 is an antiferroelectric.
A ferroelectric phase change film, 6 is an upper electrode film, and 4 'and 6' are lead portions. A lower electrode film 4, an antiferroelectric phase-ferroelectric phase change film 5, and an upper electrode film 6 are sequentially stacked on a ceramic substrate 3, and a spacer plate 1 and a pressure chamber 2 are formed below the ceramic substrate 3. I have. Lead portions 4 'and 6' are drawn out from the respective electrode films, through which electric current is supplied to the respective electrode films.

The anti-ferroelectric-ferroelectric phase change actuator according to the present invention comprises, as described above, an electrode material and an anti-ferroelectric-ferroelectric phase change material on a ceramic substrate 3 serving as a working plate such as a diaphragm. The ceramic substrate 3 and the vibrating portion (the lower electrode film 4 + the antiferroelectric-ferroelectric phase transition film 5 + the upper electrode film 6) form an integrated structure by heat treatment. The means for forming the films 4, 5, and 6 on the ceramic substrate 3 is selected from techniques such as sputtering, vacuum deposition, and screen printing. The material of each of the electrode films 4 and 6 is not particularly limited as long as it is a conductor that can withstand a heat treatment temperature and a high-temperature oxidizing atmosphere at about the baking temperature. It does not matter at all whether it is a mixture of insulating ceramics, glass, or the like and a metal or alloy, or a conductive ceramic. Most preferably, platinum, palladium, high-temperature melting precious metals such as rhodium, or silver-palladium, silver-platinum, platinum-palladium or the like as the main electrode material is used, but from the viewpoint of stability, Platinum is preferably employed.

The ceramic substrate 3 and the spacer plate 1 are formed of the same material, and are formed here as an integrally fired product of ceramics. First, a green sheet as a precursor is formed from a ceramic slurry prepared from a ceramic raw material, a binder, a solvent, and the like, using a general device such as a doctor blade device or a reverse roll coater device. Accordingly, such a green sheet can be subjected to processing such as cutting, cutting, and punching. By laminating and firing such precursors, an integral ceramic base portion (ceramic substrate 3 + spacer plate 1) is obtained. The material of the ceramic forming the ceramic base portion is not particularly limited, but alumina, zirconia, etc. are preferably used from the viewpoint of moldability and the like, and in particular, oxidized partially stabilized with a predetermined compound. A ceramic substrate 3 containing zirconium as a main component is preferable. The thickness of the ceramic substrate 3 is preferably 50
μm or less, and the thickness of the spacer plate 1 is preferably 100 μm or more.

(Embodiment 2) Next, the antiferroelectric material according to the present invention
An example in which the ferroelectric phase change film has improved phase-preserving characteristics of the phase change will be described. It is essential that a material that generates a giant strain by phase transition be an antiferroelectric substance. This antiferroelectric material shows a double hysteresis curve in the relationship between electric field and polarization as described above, and generally, antiferroelectric materials and ferroelectric materials show a structural secondary phase transition due to thermal vibration, There is a temperature at which the properties disappear (the so-called Curie point). That is, these characteristics can be rephrased as functions of temperature.

As such an antiferroelectric substance, lead zirconate, lead hafnate, and the like are known, and these materials are antiferroelectric substances.
Observed only at 200 ° C. or higher, using such a material requires an external heating mechanism such as a heater in the vicinity of the actuator, which is extremely undesirable.

Lead zirconate titanate (PZST), which is a lead zirconate titanate-derived ceramic, is
When used as an actuator, it exhibits an orthorhombic ferroelectric phase at 0 ° C or lower, a pseudotetragonal antiferroelectric phase at a temperature range of 0 ° C to 180 ° C, and a tetragonal paraelectric phase at 180 ° C or higher. Since the material exhibits sufficiently stable antiferroelectricity at room temperature, it can be said that the material can solve the above-described problem. As a result of a detailed composition search for such a material, when driving at room temperature is assumed, Pb [(Zr _x Sn _{1 -x} ) _{1 -y} Ti _y ] O ₃ (where x and y are 0 .3 ≦ x ≦ 1, 0 ≦ y ≦ 0.
2) was a composition that could be adapted for the driving at room temperature.

Embodiment 3 Next, the antiferroelectric material according to the present invention
An embodiment in which the sintering easiness of the ceramic is increased at the time of forming the ferroelectric transition film will be described. Assuming that sintering easiness is increased to obtain a ceramic sintered body from the green sheet, a small amount of La is added to PZST described in Example 2,
Evaluation for composition optimization was performed according to the following two composition series. Series A; Pb _0.98 La _0.02 (Zr _0.66 Ti _0.11-x S
n _{0.23 + x} ) _0.98 O ₃ (where x is changed in the range of 0 to 0.04) Series B; Pb _0.98 La _0.02 (Zr _{0.60 + y} Ti _0.10 S
n _0.30-y ) _0.98 O ₃ (where y is changed in the range of 0 to 0.20) FIG. 8 is a diagram conceptually showing the composition ratio at this time.
As a result, all of these compositions show a good phase transition,
Particularly, in Pb _0.98 La _0.02 (Zr _0.66 Ti _0.10 Sn _0.24 ) _0.98 O ₃ , the longitudinal distortion is + 0.50% and the lateral distortion is + 0.08%.
Got a huge distortion up to.

(Embodiment 4) Next, the antiferroelectric material according to the present invention
Another embodiment in which the sintering easiness of the ceramic is increased at the time of forming the ferroelectric transition film will be described. Here, a small amount of Nb was added to PZST described in Example 2, and evaluation for optimizing the composition was performed according to the series shown below. Series C; Pb _0.99 Nb _0.02 [(Zr _x Sn _1-x ) _1-y Ti _y ] _0.98 O
_{3 In the} above formula, C1: x = 0.55 y = 0.
065, C2: x = 0.60 y = 0.055, C3: x = 0.65 y = 0.050, C4: x = 0.70 y = 0.045. FIG. 9 is a diagram conceptually showing the composition ratio at this time. As a result, all of the above four compositions exhibited good phase transitions, and in particular, Pb _0.99 Nb _0.02 [(Zr _0.70 Sn _0.30 ) _0.955 Ti _0.045 ]
_{At 0.98} O ₃ , the vertical distortion was + 0.34% and the horizontal distortion was +0.085
A huge distortion up to% was obtained.

(Embodiment 5) Next, the construction of an ink jet printer head using the phase change actuator according to the present invention will be described. FIG. 10 is a cross-sectional view for explaining the configuration of an embodiment of the inkjet head according to the present invention.
In the figure, 7 is a nozzle reinforcing plate, 8 is a nozzle plate, 9 is a nozzle hole, and other parts having the same functions as those in FIG. 7 are denoted by the same reference numerals as those in FIG. This inkjet head
Lower electrode film 4 of platinum, antiferroelectric-ferroelectric phase change film of lead niobium zirconate titanate titanate (PNZST) 5,
An upper electrode film 6 made of platinum is sequentially laminated on a ceramic substrate 3 made of zirconia, and further, a spacer plate 1 made of zirconia forming an ink liquid chamber 2 on the opposite surface of the ceramic substrate 3, a nozzle reinforcing plate 7, It has a configuration in which a nozzle plate 8 having a nozzle hole 9 is provided. The material of the nozzle plate 8 is not particularly limited. However, in order to form the nozzle holes 9 with high dimensional accuracy, generally, plastic or a metal such as nickel or stainless steel is suitably used. In this configuration example, an ejection test was performed assuming an ink liquid chamber 2 having a width a and a depth of 2.5 mm. Table 2 below shows the presence or absence of ink ejection at this time.

[0028]

[Table 2]

As shown in Table 2, the width a of the phase change material is 2
Even at a thickness of 00 μm or less, ink could be ejected. Therefore, by using the phase change material, a more highly integrated ink jet printer head can be realized.

The phase change actuator according to the present invention is used not only as an ink jet printer head having the above-described structure but also as an ink pump for an ink jet print head having various structures, as a micro pump, a speaker, a sensor, a vibrator, a filter, and the like. Can be used.

[0031]

According to the first aspect of the present invention, the first electrode film and the antiferroelectric layer are formed on at least one surface of the ceramic substrate.
At least one of the anti-ferroelectric-ferroelectric phase transition driving units, which is a combination of a ferroelectric phase change film and a second electrode film, has a structure in which those films are sequentially laminated and formed. By using the anti-ferroelectric-ferroelectric phase change film type actuator, the anti-ferroelectric-ferroelectric phase change film can be easily formed with excellent mass productivity by the film forming method, and can be formed from the piezoelectric / electrostrictive film. Since the maximum stress is large and the volume change rate is one order of magnitude or more, the actuator can be reduced in size, highly integrated, and reduced in power consumption.

According to the second aspect of the present invention, in the first aspect, the antiferroelectric-ferroelectric phase transition film is made of Pb [(Zr _x Sn
_1-x ) _1-y Ti _y ] O ₃ (where x and y are 0.3 ≦ x ≦ 1,
By using an antiferroelectric-ferroelectric phase transition film actuator characterized by being a composition represented by the following formula (0 ≦ y ≦ 0.2), the composition exhibits antiferroelectricity at room temperature. Therefore, heating during use becomes unnecessary, and low power consumption can be achieved.

According to the third aspect of the present invention, in the first aspect, the antiferroelectric-ferroelectric phase transition film is made of Pb _{1 -z} La _z [(Zr _x Sn _{1 -x} ) _{1 -y} Ti _y ] _{1-1 / 4z} O ₃
(Where x, y, and z are 0.3 ≦ x ≦ 1, 0 ≦ y ≦ 0.2,
0 ≦ z ≦ 0.04) by using an antiferroelectric-ferroelectric phase-change film type actuator comprising PLZST as a main component, In addition, it exhibits antiferroelectricity, does not require heating during use, can reduce power consumption, and can improve the sintering characteristics of the antiferroelectric-ferroelectric phase change film. Can be obtained.

The effect of the invention of claim 4 according to claim 1, wherein the anti-ferroelectric - ferroelectric phase transition film Pb _{1-1 / 2z} Nb _z
[(Zr _x Sn _1-x ) _1-y Ti _y ] _1-z O ₃ (where x, y, z
Are 0.3 ≦ x ≦ 0.8, 0.04 ≦ y ≦ 0.2, 0 ≦ z ≦
0.04) by using the anti-ferroelectric-ferroelectric phase-change film type actuator characterized by exhibiting anti-ferroelectricity at room temperature. Heating at the time is not required, power consumption can be reduced, and excellent characteristics capable of improving the sintering characteristics of the antiferroelectric-ferroelectric phase transition film can be obtained.

According to the fifth aspect of the present invention, a high-speed, high-density, high-integration, high-speed inkjet printer head can be provided by an inkjet printer having an antiferroelectric-ferroelectric phase transition film type actuator. Can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an electric field-polarization relationship for explaining characteristics of a piezoelectric material.

FIG. 2 is a diagram illustrating a relationship between electric field and strain (displacement) for explaining characteristics of a piezoelectric material.

FIG. 3 is a diagram showing an electric field-polarization relationship for explaining characteristics of an electrostrictive material.

FIG. 4 is a diagram showing a relationship between electric field and strain (displacement) for explaining characteristics of an electrostrictive material.

FIG. 5 is a diagram showing an electric field-polarization relationship for explaining characteristics of an antiferroelectric-ferroelectric phase change material.

FIG. 6 is a diagram showing a relationship between electric field and strain (displacement) for explaining characteristics of an antiferroelectric-ferroelectric phase transition material.

FIG. 7 is a cross-sectional view illustrating a structure of an embodiment of an antiferroelectric-ferroelectric phase transition actuator according to the present invention.

FIG. 8 is a diagram conceptually showing a study composition ratio of PLZST.

FIG. 9 is a diagram conceptually showing a study composition ratio of PNZST.

FIG. 10 is a cross-sectional view illustrating a configuration of an embodiment of an ink jet head according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Spacer plate, 2 ... Pressurization room, 3 ... Ceramic substrate, 4 ... Lower electrode film, 5 ... Antiferroelectric-ferroelectric phase transition film,
6 upper electrode film, 4 ', 6' lead part, 7 nozzle reinforcing plate, 8 nozzle plate, 9 nozzle hole.

Claims (5)

[Claims] 1. An antiferroelectric-ferroelectric phase transition drive unit comprising a combination of a first electrode film, an antiferroelectric-ferroelectric phase transition film, and a second electrode film on at least one surface of a ceramic substrate. An antiferroelectric-ferroelectric phase change film type actuator, characterized in that at least one of the films has a structure in which these films are sequentially laminated in layers. 2. The antiferroelectric-ferroelectric phase change film is made of Pb.
[(Zr _x Sn _1-x ) _1-y Ti _y ] O ₃ (where x and y are 0.
2. The antiferroelectric-ferroelectric phase change film type actuator according to claim 1, wherein the composition is represented by the following formula: 3 ≦ x ≦ 1, 0 ≦ y ≦ 0.2). 3. The antiferroelectric-ferroelectric phase change film is made of Pb.
_{1-z Laz} [(Zr _x Sn _1-x ) _1-y Ti _y ] 1 _{-1 / 4z} O ₃ (where x, y, z are 0.3 ≦ x ≦ 1, 0 ≦ y ≦ 0.2, 0 ≦
2. The antiferroelectric-ferroelectric phase transition film type actuator according to claim 1, wherein the composition is represented by the following formula: z ≦ 0.04). 4. The antiferroelectric-ferroelectric phase change film is made of Pb.
_{1-1 / 2z} Nb _z [(Zr _x Sn _1-x ) _1-y Ti _y ] _1-z O ₃ (where x, y, z are 0.3 ≦ x ≦ 0.8, 0.8. 04 ≦ y ≦ 0.
2. The antiferroelectric-ferroelectric phase change film type actuator according to claim 1, wherein the composition is represented by the following formula: (2, 0 ≦ z ≦ 0.04). 5. An ink jet printer head comprising the anti-ferroelectric-ferroelectric phase transition film type actuator according to claim 1.