TWI469495B - Piezoelectric generator with a composite piezoelectric structure - Google Patents

Description

Composite piezoelectric generator

The present invention relates to a power generating device, and more particularly to a composite piezoelectric power generating device capable of improving power generation efficiency.

The piezoelectric effect is a phenomenon in which the electric field and the mechanics interact with each other. In the unit cell, if the geometric center point of the positive charge and the negative charge are not at the same point, that is, there is no symmetry center in the crystal structure, electricity is generated. Electric dipole; when subjected to stress, it will cause relative displacement of positive and negative charges, thus generating electric dipole moment or voltage, so the piezoelectric effect is caused by the lack of symmetry center in the unit cell in the crystal material. .

The piezoelectric effect includes a positive piezoelectric effect and an inverse piezoelectric effect. When a mechanical stress is applied to a piezoelectric material, both ends of the piezoelectric material are accompanied by a magnitude proportional to the mechanical stress. The charge, when the stress direction is opposite, the polarity of the charge will also be reversed; the inverse piezoelectric effect is the applied electric field on the piezoelectric material, causing the material to mechanically deform or change the internal impedance of the material. Since the discovery of piezoelectric materials, it has been widely used in various applications such as transducers, sensors, microactuators, and communication components.

Lead zirconate titanate (PZT) and zinc oxide (ZnO) are the most commonly used piezoelectric materials. As shown in Figures 1a, 1b and 1c, a piezoelectric element 91 is composed of a non-conductive material and its interior. There is no free electron to help conduct, but if a stress (for example, a stress 92 or a compressive stress 93) is applied to the piezoelectric element 91, causing internal crystal deformation, it will cause the electron 94 to move, making the piezoelectric element The force surface of 91 accumulates a charge (voltage) proportional to the magnitude of the stress. When the stress direction is opposite, the polarity of the charge (voltage) is also reversed. Therefore, when the piezoelectric material is deformed by vibration, the upper and lower sides are respectively subjected to the tensile stress and the compressive stress to collect different charges, and therefore, the piezoelectric material can be fabricated into a composite piezoelectric power generator. Power generation can also be combined with a rectifier circuit to generate DC power to provide the power required for electronic products.

Please refer to the new patent case of "Rechargeable Safety Light Shoes" of the Republic of China Announcement No. M258620, which discloses a conventional composite piezoelectric generator 8 for safety light shoes, which comprises a substrate 81 and The second piezoelectric ceramics 82, the two opposite surfaces of the substrate 81 are respectively attached to the two piezoelectric ceramics 82; wherein the conventional composite piezoelectric power generator 8 is electrically connected to the plurality of power generating elements 83 and disposed on the shoes. Bottom (not shown). Thereby, when the user walks with the shoes, the piezoelectric ceramic 82 is deformed by force and generates an electric current to cause the power generating element 83 to emit light.

When the conventional piezoelectric piezoelectric generator 8 is used, since the piezoelectric ceramic 82 is not tightly coupled to the substrate 81, the piezoelectric ceramic 82 has a low power generation efficiency, and therefore, the piezoelectric ceramic 82 needs to have a comparative A large and thick size produces sufficient power to drive the power generating component 83. Furthermore, the housing space of the bottom of the shoe is limited, and the size of the piezoelectric ceramic 82 is limited by the accommodating space, and the piezoelectric ceramic 82 cannot be accommodated. Therefore, the power generation of the conventional composite piezoelectric power generator 8 is limited.

For the above reasons, it is necessary to further improve the above-described conventional composite piezoelectric power generator 8 to provide a composite piezoelectric power generator having high power generation efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to improve the above disadvantages by providing a composite piezoelectric power generator capable of increasing power generation per unit area to provide high power generation efficiency.

A composite piezoelectric power generating device comprising: a substrate having heat resistance, and having a first bonding surface and a second bonding surface, wherein the first bonding surface and the second bonding surface are opposite surfaces; a piezoelectric layer is disposed on the first bonding surface of the substrate; a first conductive layer is disposed on the first piezoelectric layer; an isolation layer is disposed on the second bonding surface of the substrate, and the isolation The layer is made of a material having a flat adhesion layer; a second piezoelectric layer is disposed on the isolation layer; and a second conductive layer is disposed on the second piezoelectric layer.

The above and other objects, features and advantages of the present invention will become more <RTIgt; "Stainless steel substrate" means an iron alloy having a chromium content of more than 11.5% by weight, as will be understood by those of ordinary skill in the art to which the present invention pertains.

The "Modulus of Elasticity" or "Young's Coefficient" as used throughout the present invention refers to the slope of the elastic region on the stress-strain curve, and the relationship between the stress and the strain satisfies Hooke's law. In other words, the elastic coefficient represents the stiffness of the material, and the high-rigidity material has a low vibration-absorbing effect, that is, it is easier to maintain the original in the elastic load range. Shape and size, and to achieve greater energy conversion effects, will be understood by those of ordinary skill in the art to which the present invention pertains.

"Ohmic Contact" as used throughout the specification of the present invention refers to a metal semiconductor junction which is electrically conductive in both directions and whose contact resistance value is much smaller than the series resistance of a semiconductor. The drop is negligible and can be understood by those of ordinary skill in the art to which the present invention pertains.

Referring to FIG. 3, which is a preferred embodiment of the composite piezoelectric power generator of the present invention, the composite piezoelectric power generator includes a substrate 1, a first piezoelectric layer 2, a first conductive layer 3, An isolation layer 4, a second piezoelectric layer 5 and a second conductive layer 6. The first piezoelectric layer 2 is disposed on the substrate 1 , the first conductive layer 3 is disposed on the first piezoelectric layer 2 , and the isolation layer 4 is disposed on the substrate 1 and opposite to the first piezoelectric layer 2. The second piezoelectric layer 5 is disposed on the isolation layer 4, and the second conductive layer 6 is disposed on the second piezoelectric layer 5. Thereby, the first piezoelectric layer 2 and the second piezoelectric layer 5 can be deformed by force to generate electric power, and the first conductive layer 3 and the second conductive layer 6 can output electric power.

The substrate 1 is made of a material having heat resistance, for example, an alloy material, so that the substrate 1 can withstand the high temperature when other material layers (for example, the first piezoelectric layer 2 and the isolation layer 4) grow. It is made of an alloy material that is excellent in elasticity and is not prone to permanent deformation, such as stainless steel or special alloy, so that the substrate 1 can be oscillated under force, and after a long swing, the bending does not occur (Bending) ) phenomenon, resulting in permanent deformation. The substrate 1 is provided with a first bonding surface 11 and a second bonding surface 12. The first bonding surface 11 and the second bonding surface 12 are opposite surfaces. The first bonding surface 11 is configured to grow the first piezoelectric layer. Layer 2 allows the first piezoelectric layer 2 to be tightly bonded to the substrate 1. The second bonding surface 12 is used to grow the isolation layer 4. In this embodiment, the material of the substrate 1 is made of stainless steel as the embodiment, but not limited thereto; the heat resistance temperature of the substrate 1 is 200 degrees (° C.) to 500 degrees; the elastic modulus of the substrate 1 is 126. Pa (GPa) to 250 Pa. In addition, since the price of the stainless steel is lower than the price of the special alloy, the use of stainless steel as the substrate 1 can reduce the manufacturing cost of the substrate 1, and the material layers provided on the substrate 1 can be tightly bonded to the substrate 1. Combine.

The first piezoelectric layer 2 is made of a piezoelectric material, preferably a piezoelectric material such as lead zirconate titanate or zinc oxide, by radio frequency sputtering, direct current sputtering, sol-gel method, It is made by the method of hot pressing, screen printing, chemical vapor deposition, electron beam evaporation, laser deposition or atomic layer deposition. The first piezoelectric layer 2 is disposed on the first bonding surface 11 of the substrate 1 and forms opposite surfaces 21 and 22, and the first piezoelectric layer 2 can be deformed when the substrate 1 is oscillated by force. Power is generated, wherein the first piezoelectric layer 2 is tightly coupled to the first bonding surface 11. In this embodiment, the first piezoelectric layer 2 is made of lead zirconate titanate or zinc oxide.

The first conductive layer 3 is made of a conductive material by radio frequency sputtering, direct current sputtering, thermal evaporation, screen printing, chemical vapor deposition, electron beam evaporation, and laser deposition. It is made by growing in a method such as atomic layer deposition or coating. The first conductive layer 3 is disposed on the first piezoelectric layer 2 for conducting power generated by the piezoelectric layer 2, preferably parallel to the first bonding surface 11 of the substrate, to increase power transmission efficiency, wherein An ohmic contact is formed between the first conductive layer 3 and the first piezoelectric layer 2. In this embodiment, the first conductive layer 3 is made of a conductive material such as a conductive material such as gold, platinum or silver.

The isolation layer 4 is made of a material having the characteristics of a flat adhesion layer, for example Such as: Titanium Platinum, etc., by RF sputtering, DC sputtering, sol-gel method, hot pressing method, screen printing method, chemical vapor deposition method, electron beam evaporation method, laser deposition method or atomic layer deposition Made by law and other methods. The isolation layer 4 is disposed on the second bonding surface 12 of the substrate 1 , wherein the isolation layer 4 can be used in combination with the second bonding surface 12 to avoid thermal heating during manufacturing. The destruction of the second bonding surface 12 of the substrate 1, wherein the surface of the isolation layer 4 needs to have a flat microstructure. In this embodiment, the spacer layer 4 is made of titanium white gold.

The material and process of the second piezoelectric layer 5 and the first piezoelectric layer 2 are substantially the same, and are not described herein. The second piezoelectric layer 5 is disposed on the isolation layer 4 and forms opposite surfaces 51 and 52. When the substrate 1 is oscillated by force, the isolation layer 4 and the second piezoelectric layer 5 can be deformed by force. And the second piezoelectric layer 5 generates electric power. In this embodiment, the second piezoelectric layer 5 is made of lead zirconate titanate or zinc oxide.

The material and process disclosed in the second conductive layer 6 and the first conductive layer 3 are substantially the same, and are not described herein. The second conductive layer 6 is disposed on the second piezoelectric layer 5 for conducting power generated by the second piezoelectric layer 5, wherein between the second conductive layer 6 and the second piezoelectric layer 5 An ohmic contact is formed. In addition, the second conductive layer 6 is electrically connected to the first conductive layer 3 . In this embodiment, the second conductive layer 6 is made of a conductive material such as a conductive material such as gold, platinum or silver.

The composite piezoelectric power generator of the present invention may further comprise two wires (not shown) electrically connected to the first conductive layer 3 and the second conductive layer 6 for conducting the composite piezoelectric power generator of the present invention. The electricity generated.

The operation of the composite piezoelectric power generator of the present invention is detailed as follows In the case where the substrate 1 has elasticity, when the substrate 1 is deformed by force, the first piezoelectric layer 2 and the second piezoelectric layer 5 disposed on the substrate 1 can be deformed. As shown in FIG. 4a, when the substrate 1 is swung upward (in terms of the drawing), the surfaces 21 and 22 of the first piezoelectric layer 2 are respectively subjected to a stress and a compressive stress, and therefore, the surface 21 A negative charge is concentrated; the surface 22 concentrates and is conducted by the first conductive layer 3. At the same time, the surfaces 51 and 52 of the second piezoelectric layer 5 are respectively subjected to the compressive stress and the tensile stress. Therefore, the surface 51 concentrates a positive charge; the surface 52 collects a negative charge and is conducted by the second conductive layer 6. .

On the other hand, as shown in FIG. 4b, when the substrate 1 is swung downward, the surfaces 21 and 22 of the first piezoelectric layer 2 respectively collect positive and negative charges; meanwhile, the surface of the second piezoelectric layer 5 51 and 52 respectively collect a negative charge and a positive charge, which are respectively conducted by the first conductive layer 3 and the second conductive layer 6. Thereby, the composite piezoelectric power generating device of the present invention can generate an alternating current with a high power generation per unit area, thereby improving the power generation efficiency of the composite piezoelectric power generating device of the present invention, and the alternating current can be electrically connected to a rectification by the two wires. The circuit is used to rectify into a continuous current. Therefore, the composite piezoelectric power generator of the present invention can be disposed in a double-sided force application, for example, applied to wind power generation or the like.

In the composite piezoelectric power generating device of the present invention, the first piezoelectric layer 2 is disposed on the first bonding surface 11 of the substrate 1, since the first piezoelectric layer 2 is tightly bonded to the substrate 1, and the first piezoelectric layer 2 The substrate 1 is not easily separated, thereby increasing the power generation per unit area. On the other hand, the second bonding surface 12 is provided with the isolation layer 4, and the isolation layer 4 is provided with the second piezoelectric layer 5, so that the second piezoelectric layer 5 and the substrate 1 are not easily separated, thereby increasing power generation per unit area. power. Therefore, the composite piezoelectric power generator of the present invention can have a high power generation efficiency by increasing the power generation per unit area.

While the invention has been described in connection with the preferred embodiments described above, it is not intended to limit the scope of the invention. The technical scope of the invention is protected, and therefore the scope of the invention is defined by the scope of the appended claims.

〔this invention〕

1‧‧‧Substrate

11‧‧‧ first joint

12‧‧‧Second junction

2‧‧‧First piezoelectric layer

21‧‧‧ surface

22‧‧‧ Surface

3‧‧‧First conductive layer

4‧‧‧Isolation layer

5‧‧‧Second piezoelectric layer

51‧‧‧ surface

52‧‧‧ Surface

6‧‧‧Second conductive layer

[study]

91‧‧‧Piezoelectric components

92‧‧‧ tensile stress

93‧‧‧Compressive stress

94‧‧‧Electronics

8‧‧‧Knowledge composite piezoelectric generator

81‧‧‧Substrate

82‧‧‧ Piezoelectric Ceramics

83‧‧‧Power generation components

Figure 1a: Schematic diagram of the uncompressed force of a conventional composite piezoelectric power generator.

Figure 1b: Schematic diagram of the tensile stress of a conventional composite piezoelectric power generator.

Figure 1c: Schematic diagram of a conventional composite piezoelectric power generator subjected to compressive stress.

Fig. 2 is a schematic view showing the structure of a conventional composite piezoelectric power generator.

Fig. 3 is a perspective assembled view of a preferred embodiment of the composite piezoelectric power generator of the present invention.

Fig. 4a is a schematic view showing the upward swing power generation of the preferred embodiment of the composite piezoelectric power generator of the present invention.

Fig. 4b is a schematic view showing a preferred embodiment of the composite piezoelectric power generator of the present invention which swings downward to generate electricity.

1. . . Substrate

11. . . First joint surface

12. . . Second joint

2. . . First piezoelectric layer

twenty one. . . surface

twenty two. . . surface

3. . . First conductive layer

4. . . Isolation layer

5. . . Second piezoelectric layer

51. . . surface

52. . . surface

6. . . Second conductive layer

Claims (11)

A composite piezoelectric power generating device comprising: a substrate having heat resistance, and having a first bonding surface and a second bonding surface, wherein the first bonding surface and the second bonding surface are opposite surfaces; a piezoelectric layer is disposed on the first bonding surface of the substrate; a first conductive layer is disposed on the first piezoelectric layer; an isolation layer is disposed on the second bonding surface of the substrate, and the isolation The layer is made of a material having a flat adhesion layer; a second piezoelectric layer is disposed on the isolation layer; and a second conductive layer is disposed on the second piezoelectric layer. A composite piezoelectric power generator according to claim 1, wherein the substrate is made of an alloy material having elasticity. The composite piezoelectric power generator according to claim 1, wherein the substrate has a heat resistance temperature of 200 to 500 degrees. The composite piezoelectric power generator according to claim 1, wherein the substrate has a modulus of elasticity of 126 to 250 Pa. The composite piezoelectric power generator according to claim 1, wherein the substrate is made of stainless steel. The composite piezoelectric power generator according to claim 1, wherein the first piezoelectric layer and the second piezoelectric layer are made of lead zirconate titanate or zinc oxide. The composite piezoelectric power generator according to claim 1, wherein the first conductive layer and the second conductive layer are made of gold, platinum or silver. According to the composite piezoelectric power generator of claim 1, wherein The barrier layer is made of titanium white gold. The composite piezoelectric power generator of claim 1, wherein an ohmic contact is formed between the first conductive layer and the first piezoelectric layer. The composite piezoelectric power generator according to claim 1, wherein an ohmic contact is formed between the second conductive layer and the second piezoelectric layer. The composite piezoelectric power generator according to claim 1, further comprising two wires electrically connected to the first conductive layer and the second conductive layer.