JP2009165212A - Power generation element using piezoelectric material, and generating set using the power generation element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new power generation element using a piezoelectric vertical effect. <P>SOLUTION: The power generation element 100 includes: a first piezoelectric elements 110 including electrodes 111 sequentially laminated on a base material 102, a first piezoelectric material layer 113, and an electrode 112; a second piezoelectric element 120 including electrodes 121 sequentially laminated on the base material 102, a second piezoelectric material layer 123, and an electrode 112; and a vibrating member 101. One end 101a of the vibrating member 101 is fixed to the electrode 112. The other end 101b of the vibrating member 101 can vibrate in a direction which is parallel with a direction 105 in which the first piezoelectric material layer 113 and the second piezoelectric material layer 123 are connected. The first piezoelectric material layer 113 is polarized in a polarizing direction 114 which is parallel with a direction in which the electrode 111 and the electrode 112 are connected. The second piezoelectric material layer 123 is polarized in a polarizing direction 124 in which the electrodes 121 and the electrode 112 are connected. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power generation element using a piezoelectric body and a power generation apparatus using the power generation element.

  Mechanical vibrations that occur in automobile engines, home appliance compressors, motors, etc., are dissipated instead of thermal energy and sound (vibration energy of air). If these vibrational energy can be converted into electric energy and used, the energy utilization efficiency can be improved. In addition, the building vibrates due to natural phenomena such as wind and waves and the passage of moving objects. Various vibrations are also generated by human activities. If these vibrational energy can be used as the power of the device, the battery replacement cycle of the device can be extended. In addition, it is possible to eliminate the need for battery replacement for a device such as a sensor with low power consumption.

  As an element for converting vibration energy into electric energy, there is a power generation element using a piezoelectric body. This piezoelectric power generation element converts the mechanical energy of vibration into electrical energy using a phenomenon in which electrical energy is generated when a piezoelectric body is distorted.

  The principle of the piezoelectric power generation element is shown in FIGS. 16 (a) and 16 (b). In addition, hatching is abbreviate | omitted in Fig.16 (a) and (b). 16 (a) and 16 (b) includes a piezoelectric body 1 and two electrodes 2 arranged so as to sandwich the piezoelectric body 1 therebetween. The piezoelectric body 1 is polarized in the direction of the polarization direction 1a. As shown in FIG. 16A, when pressure 3 is applied from the outside in a direction parallel to the polarization direction 1a to distort the piezoelectric body 1, charges are generated in a direction parallel to the strain direction. This phenomenon is called the piezoelectric longitudinal effect. Further, as shown in FIG. 16B, when the piezoelectric body 1 is distorted by applying pressure from the outside in a direction perpendicular to the polarization direction 1a, an electric charge is generated in a direction perpendicular to the direction of the strain. This phenomenon is called the piezoelectric lateral effect. When the resistor 4 is connected to the electrode 2, the generated charge moves and a current flows. The efficiency with which work applied to the piezoelectric body is converted into electrical energy is generally twice or more higher in the piezoelectric longitudinal effect than in the piezoelectric lateral effect.

  As a power generation element using the piezoelectric lateral effect, an element has been proposed in which one of the piezoelectric elements is fixed and a weight is attached to the other, and the piezoelectric body is bent by vibration of the weight (Patent Document 1). In this power generation element, the piezoelectric body expands and contracts in the plane direction due to bending, and charges are generated in the thickness direction of the piezoelectric body. The generation of this electric charge is taken out as electric power. However, there is a problem that the conversion efficiency of the piezoelectric lateral effect is low.

In addition, a piezoelectric power generating element using the piezoelectric longitudinal effect has been proposed (Patent Document 2). In this power generation element, an action point is provided between the free end and the support end of the vibration member, and the piezoelectric body is distorted by this action point. However, the power generating element of Patent Document 2 has a complicated structure and has a limit in miniaturization. Therefore, the power generating elements cannot be arranged closely.
Japanese Patent Laid-Open No. 10-174462 Japanese Patent Laid-Open No. 11-146663

  Under such circumstances, there is a demand for a power generation element that has high energy conversion efficiency and can be arranged closely. In order to meet such a demand, an object of the present invention is to provide a novel power generation element using the piezoelectric longitudinal effect.

  In order to achieve the above object, a power generation element of the present invention includes a first electrode including a first electrode, a first piezoelectric layer, and a second electrode, which are sequentially stacked on a substrate, and the base. It includes a third electrode, a second piezoelectric layer including a fourth piezoelectric layer and a fourth electrode, which are sequentially stacked on the material, and a vibration member. One end of the vibrating member is fixed to the second and fourth electrodes. The other end of the vibration member opposite to the one end can vibrate in a direction parallel to a direction connecting the first piezoelectric layer and the second piezoelectric layer. The first piezoelectric layer is polarized in a direction parallel to a direction connecting the first electrode and the second electrode. The second piezoelectric layer is polarized in a direction parallel to a direction connecting the third electrode and the fourth electrode.

  Moreover, the power generation device of the present invention is a power generation device including a plurality of power generation elements formed on a base material, and each of the plurality of power generation elements is a first electrode laminated in order on the base material. A first piezoelectric element including a first piezoelectric layer and a second electrode; a third electrode sequentially stacked on the substrate; a second electrode including a second piezoelectric layer and a fourth electrode; A piezoelectric element and a vibration member. One end of the vibrating member is fixed to the second and fourth electrodes. The other end of the vibration member opposite to the one end can vibrate in a direction parallel to a direction connecting the first piezoelectric layer and the second piezoelectric layer. The first piezoelectric layer is polarized in a direction parallel to a direction connecting the first electrode and the second electrode. The second piezoelectric layer is polarized in a direction parallel to a direction connecting the third electrode and the fourth electrode.

  In the power generation element of the present invention, the vibration of the vibration member is effectively used by being divided into two components, ie, expansion and compression of the first and second piezoelectric layers. In the power generation element of the present invention, power is generated using the piezoelectric longitudinal effect. Therefore, according to the present invention, a power generation element with high energy conversion efficiency can be obtained. In the power generation element of the present invention, one end of the vibration member is fixed and the other end is a free end. According to this configuration, it is possible to arrange a plurality of power generation elements in a dense arrangement. The power generation device of the present invention uses the power generation element of the present invention. Therefore, efficient power generation in a small area is possible.

  Hereinafter, embodiments of the present invention will be described with examples. The present invention is not limited to the following embodiment. In the following description, specific numerical values and specific materials may be exemplified, but other numerical values and other materials may be applied as long as the effect of the present invention is obtained.

[Power generation element]
The power generation element of the present invention includes a first piezoelectric element, a second piezoelectric element, and a vibration member. The first piezoelectric element includes a first electrode, a first piezoelectric layer, and a second electrode, which are sequentially stacked on the base material. The second piezoelectric element includes a third electrode, a second piezoelectric layer, and a fourth electrode, which are sequentially stacked on the base material. One end (fixed end) of the vibration member is fixed to the second and fourth electrodes. In addition, as long as the effect of this invention is acquired, a piezoelectric element may also contain layers other than an electrode and a piezoelectric material layer. For example, a layer for controlling the polarization direction of the piezoelectric layer may be included between the electrode and the piezoelectric layer.

  The other end (free end) opposite to the one end (fixed end) of the vibration member can vibrate in a direction parallel to the direction connecting the first piezoelectric layer and the second piezoelectric layer. The first piezoelectric layer is polarized in a direction parallel to the direction connecting the first electrode and the second electrode. The second piezoelectric layer is polarized in a direction parallel to the direction connecting the third electrode and the fourth electrode.

  The first piezoelectric element and the second piezoelectric element may be formed of different materials. However, since both are usually formed in the same process, the first piezoelectric element and the second piezoelectric element are generally made of the same material.

  The first electrode of the first piezoelectric element and the third electrode of the second piezoelectric element are fixed to the base material side. The first and third electrodes may be directly fixed to the base material, or may be indirectly fixed to the base material with another member interposed therebetween. There is no limitation in particular in a base material, What is necessary is just what can fix a piezoelectric element. The base material may be a part of an object (for example, a structure or a moving body) that generates vibration. The power generating element of the present invention can be directly fixed to those objects. Therefore, the base material is not an essential component of the power generation element and power generation device of the present invention.

  The first and second piezoelectric layers may be formed of different materials, but are usually formed of the same material. As long as the effects of the present invention are obtained, there is no limitation on the material of the first and second piezoelectric layers. For the first and second piezoelectric layers, for example, a lead zirconate titanate (PZT) or a piezoelectric body to which other elements are added can be used. The first to fourth electrodes are formed of a conductive material such as metal. These electrodes may be formed of a noble metal material alloy (Pt, Ir, etc. added with Ti, Co, etc.) that controls the orientation characteristics of the piezoelectric body.

  The thickness of the first and second piezoelectric layers is not limited as long as the effects of the present invention are obtained. The first and second piezoelectric layers are usually thin films, but may not be thin films. In one example, the thicknesses of the first and second piezoelectric layers are each in the range of 0.5 μm to 100 μm.

  The first piezoelectric layer is polarized in a direction parallel to the direction connecting the first electrode and the second electrode. Therefore, when a strain that is expanded or compressed in a direction connecting the first electrode and the second electrode is applied to the first piezoelectric layer, an electromotive force based on the piezoelectric longitudinal effect is generated. The second piezoelectric layer is polarized in a direction parallel to the direction connecting the third electrode and the fourth electrode. Therefore, when a strain that is extended or compressed in the direction connecting the third electrode and the fourth electrode is applied to the second piezoelectric layer, an electromotive force based on the piezoelectric longitudinal effect is generated. The direction of polarization of the first piezoelectric layer and the direction of polarization of the second piezoelectric layer may be the same or opposite. Their polarization directions are determined in consideration of the electrode connection method.

  One end (fixed end) of the vibration member is fixed to the second and fourth electrodes. That is, the vibrating member is disposed on the second and fourth electrodes. The fixed end of the vibration member may be directly fixed to the second and fourth electrodes, or may be indirectly fixed to the second and fourth electrodes with another member such as an adhesive layer interposed therebetween. Good. The other end of the vibration member can vibrate in a direction parallel to the direction connecting the first piezoelectric layer and the second piezoelectric layer. Hereinafter, this direction may be referred to as an “effective vibration direction”. The other end (free end) of the vibration member may be capable of vibrating in a direction other than the effective vibration direction. As long as the vibration member can vibrate in the effective vibration direction, the shape and material of the vibration member are not limited. An example of the shape of the vibration member is an elongated rectangular parallelepiped shape. Examples of the material of the vibration member include a material having a high aspect ratio such as a chemically amplified resist or nickel formed by plating, and silicon formed by etching.

  When the other end of the vibration member vibrates in the effective vibration direction, the first and second piezoelectric layers are stretched or compressed. Specifically, when the first piezoelectric layer is stretched in a direction parallel to the polarization direction, the second piezoelectric layer is compressed in a direction parallel to the polarization direction. Further, when the first piezoelectric layer is compressed in a direction parallel to the polarization direction, the second piezoelectric layer is expanded in a direction parallel to the polarization direction. Therefore, when the polarization direction of the first piezoelectric layer is the same as the polarization direction of the second piezoelectric layer, the electromotive force of the first piezoelectric element and the second piezoelectric force are accompanied by the vibration of the vibration member. It is generated in the opposite direction to the electromotive force of the element. Further, when the polarization direction of the first piezoelectric layer and the polarization direction of the second piezoelectric layer are opposite directions, the electromotive force of the first piezoelectric element and the second piezoelectric force are accompanied by the vibration of the vibration member. The electromotive force of the element is generated in the same direction. The power generating element of the present invention is configured such that the electromotive force generated in the first piezoelectric layer and the electromotive force generated in the second piezoelectric layer do not cancel each other. For this reason, the electric power generated in the first piezoelectric element and the electric power generated in the second piezoelectric element are taken out without canceling each other.

  You may take out separately the output of a 1st piezoelectric element, and the output of a 2nd piezoelectric element. Further, the electrode of the first piezoelectric element and the electrode of the second piezoelectric element may be connected and connected in series or in parallel. In this case, the outputs of the first and second piezoelectric elements are added and taken out.

  As described above, the power generation element of the present invention includes the first and second piezoelectric elements formed on the base material and the vibration member fixed on the piezoelectric elements. The expansion and contraction of the piezoelectric layer of the first piezoelectric element caused by the vibration of the vibration member and the expansion and contraction of the piezoelectric layer of the second piezoelectric element caused by the vibration of the vibration member are reversed.

  In the power generating element of the present invention, the first piezoelectric layer and the second piezoelectric layer may be polarized in the same direction. And any one set of electrodes may be connected among one set of electrodes consisting of the first electrode and the third electrode, and one set of electrodes consisting of the second electrode and the fourth electrode. . In this configuration, the first piezoelectric element and the second piezoelectric element are connected in series so that their outputs are added. That is, the first electromotive force generated when the first piezoelectric layer is stretched and the electromotive force generated when the second piezoelectric layer is compressed have the same direction on the circuit. The piezoelectric element and the second piezoelectric element are connected in series. Of course, the electromotive force generated when the first piezoelectric layer is compressed and the electromotive force generated when the second piezoelectric layer is expanded are added in series in the same direction on the circuit. In this configuration, the output voltage of the first piezoelectric element and the output voltage of the second piezoelectric element are added.

  In the power generating element of the present invention, the first piezoelectric layer and the second piezoelectric layer may be polarized in the same direction. The first electrode and the fourth electrode may be connected, and the second electrode and the third electrode may be connected. According to this configuration, the first piezoelectric element and the second piezoelectric element are connected in parallel so that outputs are added. That is, the first electromotive force generated when the first piezoelectric layer is stretched and the electromotive force generated when the second piezoelectric layer is compressed have the same direction on the circuit. The piezoelectric element and the second piezoelectric element are connected in parallel. Of course, the electromotive force generated when the first piezoelectric layer is compressed and the electromotive force generated when the second piezoelectric layer is expanded are in the same direction on the circuit. In this configuration, the output current of the first piezoelectric element and the output current of the second piezoelectric element are added.

  In the power generating element of the present invention, the polarization direction of the first piezoelectric layer and the polarization direction of the second piezoelectric layer may be opposite. The first electrode and the third electrode may be connected, and the second electrode and the fourth electrode may be connected. According to this configuration, the electromotive force of the first piezoelectric element and the electromotive force of the second piezoelectric element are generated in the same direction as the vibration member vibrates. Those electromotive forces are connected in parallel.

  In the power generation element of the present invention, the first and third electrodes may be directly fixed on the substrate. According to this configuration, since the distortion generated by the vibration of the vibration member is applied to the piezoelectric body without being absorbed by other portions, the generated electric power can be increased.

  In the power generation element of the present invention, a buffer member that can be deformed in accordance with the vibration of the vibration member may be disposed between the base material and the first electrode and between the base material and the third electrode. . By disposing the buffer member between the base material and the piezoelectric element, it is possible to prevent excessive distortion from being applied to the piezoelectric body. Therefore, according to this configuration, it is possible to prevent the piezoelectric body from being damaged due to excessive vibration of the vibration member. There is no limitation on the material of the buffer member, and it is preferable to select a material having high adhesion to the electrode. For example, you may form using the same material as a vibration member.

  In the power generation element of the present invention, another piezoelectric element using a piezoelectric body may be formed in the middle of the buffer member. According to this configuration, it is possible to prevent damage to the piezoelectric body and to extract more electric power. As the other piezoelectric elements, elements having the same structure as the first and second piezoelectric elements are usually used.

  In the power generation element of the present invention, one or more other first piezoelectric elements are laminated between the base material and the first piezoelectric element, and the other is provided between the base material and the second piezoelectric element. One or more of the second piezoelectric elements may be laminated. According to this configuration, it is possible to extract more power. If the polarization directions of the piezoelectric layers of the plurality of stacked first piezoelectric elements are the same, the outputs of the first piezoelectric elements are added without canceling each other. Similarly, if the polarization directions of the piezoelectric layers of the plurality of stacked second piezoelectric elements are the same, the outputs of the second piezoelectric elements are added without canceling each other.

  In the power generation element of the present invention, a weight made of a material having a specific gravity greater than that of the vibration member may be fixed to the other end (free end) of the vibration member. According to this configuration, since the inertial force applied to the vibration member can be increased, the generated electric power can be increased. There is no limitation on the shape and material of the weight as long as the generated power can be increased. The weight can be formed, for example, by plating Ni or Cu using a resist as a mold.

  In the power generation element of the present invention, the first piezoelectric layer and the second piezoelectric layer may be integrated to form one piezoelectric layer. In this configuration, a part of one piezoelectric layer and the other part function as a first piezoelectric layer of the first piezoelectric element and a second piezoelectric layer of the second piezoelectric element, respectively. .

[Power generation equipment]
The power generation device of the present invention is a power generation device including a plurality of power generation elements formed on a substrate. The plurality of power generation elements are the power generation elements of the present invention. Since the power generating element of the present invention has been described above, a duplicate description is omitted.

  In the power generation device of the present invention, the plurality of power generation elements may be arranged so that directions connecting the first electrode and the third electrode are parallel to each other. According to this configuration, all the power generation elements similarly generate power when oscillating in one effective vibration direction. In the power generation device of the present invention, the plurality of power generation elements may not be arranged so that the directions connecting the first electrode and the third electrode are parallel to each other. By arranging the power generation elements in different directions, it is possible to generate power even when oscillating in various directions.

  In the power generation device of the present invention, two adjacent power generation elements may be connected in series. By connecting a plurality of power generation elements in series so that the output voltages of the respective power generation elements are added, the output voltage can be increased. In the power generation device of the present invention, two adjacent power generation elements may be connected in parallel so that the output currents of the respective power generation elements are added.

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

[Embodiment 1]
A top view of the power generating element of the first embodiment is shown in FIG. A cross-sectional view taken along line IIa-IIa in FIG. 1 is shown in FIG. 2A, and a cross-sectional view taken along line IIb-IIb is shown in FIG. In addition, illustration of a base material is abbreviate | omitted in FIG.

  The power generation element 100 in FIG. 1 includes a vibration member 101. Referring to FIG. 2, power generation element 100 includes a base material 102, and a first piezoelectric element 110 and a second piezoelectric element 120 formed on base material 102. On the base material 102, electrical wirings 103a and 103b are formed.

  Referring to FIG. 2, the first piezoelectric element 110 is constituted by electrodes 111 and 112 (first and second electrodes) and a first piezoelectric layer 113 disposed therebetween. . The electrode 111 is laminated on the base material 102. The electrode 111 is fixed to the base material 102 side through the electric wiring 103a. The first piezoelectric layer 113 is polarized in the polarization direction 114. The polarization direction 114 is parallel to the direction connecting the electrode 111 and the electrode 112.

  The second piezoelectric element 120 includes electrodes 121 and 112 (third and fourth electrodes) and a second piezoelectric layer 123 disposed between them. The electrode 112 serves as both the electrode (second electrode) of the first piezoelectric element 110 and the electrode (fourth electrode) of the second piezoelectric element 120. From another viewpoint, the electrode on the vibration member 101 side of the piezoelectric element 110 and the electrode on the vibration member 101 side of the piezoelectric element 120 are connected. The electrode 121 is laminated on the base material 102. The electrode 121 is fixed to the base material 102 side through the electric wiring 103b. The second piezoelectric layer 123 is polarized in the direction of the polarization direction 124. The polarization direction 124 is parallel to the direction connecting the electrode 121 and the electrode 112. In the power generating element 100, the polarization direction 114 of the first piezoelectric layer 113 and the polarization direction 124 of the second piezoelectric layer 123 are the same direction, and both are in the direction from the vibrating member 101 side to the base material 102 side. is there.

  One end 101a of the vibration member 101 is fixed to the electrode 112 (second and fourth electrodes). The vibration member 101 has a rectangular parallelepiped shape. The vibration member 101 is arranged so that the longitudinal direction thereof is parallel to the stacking direction of the components of the piezoelectric element (direction perpendicular to the surface of the base material 102). The other end 101 b of the vibration member 101 is not fixed and can vibrate in a direction parallel to the direction 105 connecting the first piezoelectric layer 113 and the second piezoelectric layer 123.

  As shown in FIGS. 1 and 2A, the power generating element of the present invention usually has a plane-symmetric structure with respect to a plane perpendicular to the direction 105 and passing through the central axis of the vibration member 101.

  The power generation principle of the power generation element 100 will be described with reference to FIGS. 3 (a) and 3 (b). In FIGS. 3A and 3B, the piezoelectric layer is not hatched. An arrow in the piezoelectric layer indicates the direction of strain.

  When the substrate 102 vibrates in a direction parallel to the direction 105, the other end 101b of the vibration member 101 vibrates due to inertial force. As shown in FIG. 3A, when the other end 101b is bent toward the piezoelectric element 110, the first piezoelectric layer 113 is compressed and the second piezoelectric layer 123 is expanded. As shown in FIG. 3B, when the other end 101b is bent toward the piezoelectric element 120, the first piezoelectric layer 113 is expanded and the second piezoelectric layer 123 is compressed.

  When the first piezoelectric layer 113 and the second piezoelectric layer 123 are compressed or expanded, electric power due to the piezoelectric longitudinal effect is generated. Since the first piezoelectric layer 113 and the second piezoelectric layer 123 have the same polarization direction, the electromotive force generated in the first piezoelectric element 110 regardless of which direction the vibration member 101 bends. Is opposite to the direction of the electromotive force generated in the second piezoelectric element 120. Therefore, by using the electrode 112 as a common electrode, the electric power generated in the first piezoelectric element 110 and the electric power generated in the second piezoelectric element 120 can be extracted without canceling each other. In the power generation element 100, the voltage generated in the first piezoelectric element 110 and the voltage generated in the second piezoelectric element 120 are added together.

  An example of a circuit connected to the power generation element 100 of Embodiment 1 is shown in FIG. The circuit 140 in FIG. 4 functions as a rectifier circuit and a power storage circuit. Circuit 140 includes a full-wave rectifier circuit 141 composed of four diodes, and a capacitor 142. Outputs extracted from the electrical wirings 103 a and 103 b are rectified by the full-wave rectifier circuit 141 and accumulated in the capacitor 142.

  1 to 4, the power generation element 100 in which the polarization directions 114 and 124 of the piezoelectric layer are directed from the vibrating member 101 side to the base material 102 side has been described. However, the polarization directions 114 and 124 may be opposite directions (the same applies to other embodiments). Even in this case, similarly to the power generation element 100, the output of the first piezoelectric element 110 and the output of the second piezoelectric element 120 are taken out without canceling each other.

  1 to 4, the power generation element 100 in which the first piezoelectric layer 113 and the second piezoelectric layer 123 are separate piezoelectric bodies has been described. However, when the vibrating member 101 vibrates, distortion (compression or expansion) of the piezoelectric layer between the two electrodes of the first piezoelectric element and distortion (compression) of the piezoelectric layer between the two electrodes of the second piezoelectric element. As long as (or extension) is reversed, the piezoelectric layer between the two electrodes of the first piezoelectric element and the piezoelectric layer between the two electrodes of the second piezoelectric element may be integrated. . That is, a part of one piezoelectric layer and the other part may be the first piezoelectric layer 113 and the second piezoelectric layer 123, respectively (the same applies to the following embodiments). .

  1 to 4, the electrode on the vibration member 101 side of the first piezoelectric element 110 and the electrode on the vibration member 101 side of the second piezoelectric element 120 are connected to form a common electrode 112. The power generation element 100 is shown. However, the electrode on the base material 102 side of the first piezoelectric element 110 and the electrode on the base material 102 side of the second piezoelectric element 120 may be connected to form a common electrode. An example of such a power generation element 100a is shown in FIG.

  The power generation element 100a of FIG. 5 includes an electrode 151 disposed on the base material 102. The electrode 151 functions as an electrode on the base material 102 side of the first piezoelectric element 110 and an electrode on the base material 102 side of the second piezoelectric element 120. FIG. 5 shows an example in which the polarization direction 114 of the first piezoelectric layer 113 and the polarization direction 124 of the second piezoelectric layer 123 are directions from the substrate 102 side to the vibrating member 101 side. However, these polarization directions may be reversed.

[Embodiment 2]
In the second embodiment, a power generation element having a different electrode connection method compared to the power generation element 100 of the first embodiment will be described. The configuration of the power generation element 100b according to the second embodiment and an example of a circuit connected thereto is schematically shown in FIG.

  In the power generation element 100a, the electrode 112 (see FIG. 2A) of the power generation element 100 is divided into an electrode 161 (second electrode) and an electrode 162 (fourth electrode). In addition, the electrode 111 and the electrode 162 are connected by a wiring, and the electrode 161 and the electrode 121 are connected by a wiring. Parts other than these electrodes are the same as those of the power generation element 100. The circuit 140 is the same as the circuit 140 described in the first embodiment.

  In the power generation element 100a, the polarization direction 114 of the first piezoelectric layer 113 and the polarization direction 124 of the second piezoelectric layer 123 are the same. Therefore, as described in the first embodiment, when the vibrating member 101 vibrates, the first piezoelectric layer 113 and the second piezoelectric layer 123 generate electromotive forces in opposite directions. In the power generation element 100b, the first piezoelectric element 110 and the second piezoelectric element 120 are connected in parallel so that their electromotive forces do not cancel each other. As a result, the output current of the first piezoelectric element 110 and the output current of the second piezoelectric element 120 are added together.

[Embodiment 3]
In the third embodiment, a power generation element in which the polarization direction of the piezoelectric layer and the electrode connection method are different from those of the power generation element 100 of the first embodiment will be described. The configuration of the power generation element 100c of the third embodiment and an example of a circuit connected thereto is schematically shown in FIG.

  In the power generation element 100c, the polarization direction 114 of the first piezoelectric layer 113 and the polarization direction 124 of the second piezoelectric layer 123 are opposite to each other. In the power generation element 100c, a common electrode 171 is used instead of the electrodes 111 and 121 (see FIG. 2A) of the power generation element 100. In another aspect, the electrode 171 is an electrode in which the electrode 111 and the electrode 121 are connected. The power generation element 100c is the same as the power generation element 100 except for the polarization direction of the piezoelectric layer and the configuration of the electrodes. The circuit 140 is the same as the circuit 140 described in the first embodiment.

  In the power generation element 100c, when the other end 101b of the vibration member 101 vibrates, the direction of the voltage generated in the first piezoelectric element 110 is the same as the direction of the voltage generated in the second piezoelectric element 120. In the power generation element 100c, the electrodes on the base material side of the two piezoelectric elements are common, and the electrodes on the vibration member side of the two piezoelectric elements are common. That is, in the power generation element 100 c, the first piezoelectric element 110 and the second piezoelectric element 120 are prevented from canceling out the voltage generated in the first piezoelectric element 110 and the voltage generated in the second piezoelectric element 120. And are connected in parallel.

[Embodiment 4]
In the fourth embodiment, an example in which a buffer member that relaxes strain applied to the piezoelectric body is disposed between the base material and the piezoelectric element will be described. A cross-sectional view of the power generation element 100d of the fourth embodiment is shown in FIG.

  The power generation element 100 d includes a base material 102, electric wires 103 a and 103 b, take-out wires 181 a and 181 b, buffer members 182 and 183, a first piezoelectric element 110, a second piezoelectric element 120, and a vibration member 101. The base material 102, the electric wirings 103 a and 103 b, the first piezoelectric element 110, the second piezoelectric element 120, and the vibration member 101 are the same as those of the power generation element 100.

  The buffer member 182 is disposed between the electrode 111 of the first piezoelectric element 110 and the base material 102 (electrical wiring 103a). The buffer member 183 is disposed between the electrode 121 of the second piezoelectric element 120 and the base material 102 (electrical wiring 103b). When the vibration member 101 vibrates in the effective vibration direction, the buffer members 182 and 183 are deformed accordingly and vibrate in a direction parallel to the effective vibration direction. The buffer members 182 and 183 can suppress damage to the piezoelectric body due to excessive vibration. There is no limitation on the material of the buffer members 182 and 183 as long as damage to the piezoelectric body can be prevented and sufficient adhesion to the electrode material can be obtained. For example, the buffer members 182 and 183 may be formed of the same material as that of the vibration member 101.

  The electrode 111 and the electrical wiring 103a are connected by the extraction wiring 181a. The electrode 121 and the electrical wiring 103b are connected by the extraction wiring 181b. The take-out wiring is preferably formed on the surface where the buffer member 182 and the buffer member 183 face each other. A portion away from the central axis of the power generation element is greatly deformed due to vibration of the vibration member 101. For this reason, when the lead-out wiring is formed in a portion away from the central axis of the power generation element, the wiring is easily disconnected.

  In addition, you may arrange | position another piezoelectric element in the middle of a buffer member. A cross-sectional view of such a power generation element 100e is shown in FIG.

  In the power generation element 100e, the first piezoelectric element 110a is formed in the middle of the buffer member 182. A second piezoelectric element 120 a is formed in the middle of the buffer member 183. The number of piezoelectric elements formed in the middle of the buffer member 182 may be two or more. Similarly, the number of piezoelectric elements formed in the middle of the buffer member 183 may be two or more. Usually, the number of piezoelectric elements formed in the middle of the buffer member 182 and the number of piezoelectric elements formed in the middle of the buffer member 183 are the same.

  The piezoelectric elements 110a and 120a and the piezoelectric elements 110 and 120 differ only in that the electrode 112 is divided into electrodes 184 and 185. The polarization direction 114 of the piezoelectric layer of the first piezoelectric element 110 is the same as the polarization direction of the piezoelectric layer of the first piezoelectric element 110a. The polarization direction 124 of the piezoelectric layer of the second piezoelectric element 120 is the same as the polarization direction of the piezoelectric layer of the second piezoelectric element 120a.

  The electrode 111 of the first piezoelectric element 110 and the electrode 184 of the first piezoelectric element 110a are connected by an extraction wiring 181a. The electrode 121 of the second piezoelectric element 120 and the electrode 185 of the second piezoelectric element 120a are connected by an extraction wiring 181b. The electrode 111 of the piezoelectric element 110a and the electric wiring 103a are connected to each other by a lead-out wiring 181a. The electrode 121 of the piezoelectric element 120a and the electric wiring 103b are connected by the extraction wiring 181b.

  When the vibrating member 101 bends upward in FIG. 8B, the piezoelectric layers of the first piezoelectric elements 110 and 110a are both compressed in a direction parallel to the polarization direction, and the second piezoelectric elements 120 and 120a Both piezoelectric layers are stretched in a direction parallel to the polarization direction. When the vibrating member 101 bends downward in FIG. 8B, the piezoelectric layers of the first piezoelectric elements 110 and 110a are both extended in a direction parallel to the polarization direction, and the second piezoelectric element 120 and Both of the piezoelectric layers 120a are compressed in a direction parallel to the polarization direction. Accordingly, the first piezoelectric element 110 and the first piezoelectric element 110a generate voltages in the same direction, and these voltages are added together. Similarly, the voltage generated in the second piezoelectric element 120 and the voltage generated in the second piezoelectric element 120a are added together. The direction of the voltage of the first piezoelectric elements 110 and 110a is opposite to the direction of the voltage of the second piezoelectric elements 120 and 120a. Here, since the electrode 112 is a common electrode, the voltages of the four piezoelectric elements are added in series without canceling each other.

[Embodiment 5]
In the fifth embodiment, an example of a power generation element in which a plurality of piezoelectric elements are stacked will be described. A cross-sectional view of the power generation element 100f of the fifth embodiment is shown in FIG.

  In the power generation element 100f, the first piezoelectric elements 110a and 110 are stacked on the electric wiring 103a. The second piezoelectric elements 120a and 120 are stacked on the electric wiring 103b. The directions of polarization of the piezoelectric layers included in the four power generation elements are the same. Note that the number of power generating elements stacked may be three or more. Usually, the number of first piezoelectric elements stacked is the same as the number of second piezoelectric elements stacked.

  The electrode on the vibrating member 101 side of the first piezoelectric element 110a and the electrode 111 on the base material 102 side of the first piezoelectric element 110 are common. The electrode on the vibrating member 101 side of the second piezoelectric element 120a and the electrode 121 on the base material 102 side of the second piezoelectric element 120 are common. The electrode on the vibrating member 101 side of the first piezoelectric element 110 and the electrode on the vibrating member 101 side of the second piezoelectric element 120 are connected. Therefore, the four piezoelectric elements are connected in series. Similarly to the power generation element 100e of FIG. 8B, in the power generation element 100f, the voltages of the four piezoelectric elements are added in series without canceling each other.

[Embodiment 6]
In the sixth embodiment, an example of a power generation element in which a weight is fixed to the free end of the vibration member will be described. A cross-sectional view of the power generation element 100g of the sixth embodiment is shown in FIG.

  The power generation element 100 g includes a weight 200 fixed to the other end 101 b of the vibration member 101. The weight 200 is made of a material having a specific gravity greater than that of the vibration member 101. Other components are the same as those of the power generation element 100.

  In the power generation element 100g, since the weight 200 exists, the inertia force generated by the acceleration increases, and the obtained electric power increases. Further, by adjusting the mass of the weight 200, the frequency of external vibration and the natural frequency of the vibration member 101 can be matched. At this time, the amplitude of the vibration member 101 is increased, and the obtained electric power can be further increased.

[Embodiment 7]
In the seventh embodiment, an example of a power generation apparatus including a plurality of power generation elements 100 and a method for manufacturing the power generation apparatus will be described. Unless otherwise specified, the following steps can be performed by a method used in a semiconductor element manufacturing process, such as a vapor deposition method, a photolithography method, an etching method, and a lift-off method.

  First, as shown in FIG. 11A, a metal layer 212, a piezoelectric layer 213, and a metal layer 214 are formed on a substrate 211 by sputtering. These layers may be formed by a film formation method other than the sputtering method. The substrate 211 is a substrate that becomes the vibration member 101 in a later process.

  Next, the metal layer 212, the piezoelectric layer 213, and the metal layer 214 are patterned by formation of a resist pattern and dry etching. As a result, as shown in FIG. 11B, four piezoelectric elements 110 and four piezoelectric elements 120 are formed. The polarization directions of the piezoelectric layers of all the piezoelectric elements are the same. The polarization direction of the piezoelectric layer of the piezoelectric element may be controlled when the piezoelectric layer 213 is formed. Further, the polarization direction of the piezoelectric layer of the piezoelectric element may be performed by a poling process using the metal layers 212 and 214 or the electrodes (metal layer after patterning). In addition, the orientation direction may be controlled at the time of film formation, and further poling treatment may be performed.

  Next, the base material 102 on which the electrical wiring 215 is formed is prepared. The electric wiring 215 also serves as the electric wiring 103a and the electric wiring 103b in FIG. Then, the electrode 111 of the piezoelectric element 110 and the electrode 121 of the piezoelectric element 120 are bonded onto the electric wiring 215. These adhesions are performed using a conductive adhesive in order to fix and electrically connect the piezoelectric element. In addition, what is necessary is just to perform these adhesion | attachment by the method in which fixation and electrical connection of a piezoelectric element are achieved. For example, these adhesions may be performed using an anisotropic conductive sheet. Moreover, these adhesion | attachments may be performed by the method of connecting metals by an ultrasonic wave or a heating.

  Next, the vibration member 101 is formed for each power generation element 100 by removing unnecessary portions of the substrate 211. In this way, the power generation device 210 of Embodiment 7 is obtained. As shown in FIG. 11, a power generation device in which a large number of power generation elements are arranged closely can be easily formed by thin film formation, photolithography, and dry etching. In this manufacturing method, most of the piezoelectric layer 213 can be used as the piezoelectric layer of the piezoelectric element.

  The formation of the power generation element alone can also be performed by the same method as that for the power generation apparatus. As described above, the power generating element and the power generating device of the present invention can be manufactured using a known technique used in a semiconductor manufacturing process.

  An example of the electrical wiring is shown in FIG. In FIG. 12, the power generation element 100 is present at each location where the vibration member 101 is disposed. In the example of FIG. 12, 20 power generating elements 100 are arranged in a matrix of 4 rows × 5 columns. The electrical wiring 103 a of one power generation element 100 and the electrical wiring 103 b of the adjacent power generation element 100 are connected by a wiring 221. In addition, the electrical wiring 103 a of the power generation element 100 present at the end of one row and the electrical wiring 103 b of the power generation element 100 present at the end of the adjacent row are connected by a wiring 221. As a result, all the power generating elements 100 are connected in series.

  In the example of FIG. 12, the direction 222 connecting the electrode on the electric wiring 103a (the electrode 111 in FIG. 2A) and the electrode on the electric wiring 103b (the electrode 121 in FIG. 2A) is parallel to each other. In addition, each power generating element 100 is arranged. That is, all the power generating elements 100 are arranged in the same direction. Therefore, when external vibration is applied, the vibration members of all the power generation elements 100 are deformed in the same direction. As a result, all the power generating elements 100 generate power in the same manner, and their outputs are added in series. It is possible to adjust the output voltage by adjusting the number of power generating elements connected in series.

[Embodiment 8]
In the eighth embodiment, an example of a power generation device including a plurality of power generation elements 100a (see FIG. 5) and a method for manufacturing the power generation device will be described. Unless otherwise specified, the following steps can be performed by a method used in a semiconductor element manufacturing process, such as a vapor deposition method, a photolithography method, an etching method, and a lift-off method.

  First, as shown in FIG. 13A, a metal layer 231 and a piezoelectric layer 232 are formed on a base material 102 by a sputtering method. These layers may be formed by a film formation method other than the sputtering method.

  Next, as shown in FIG. 13B, the metal layer 231 and the piezoelectric layer 232 are patterned by forming a resist pattern and performing dry etching. By this patterning, the electrode 151 and the piezoelectric layers 113 and 123 are formed. The polarization directions of all the piezoelectric layers are the same.

  Next, as shown in FIG. 13C, the insulator layer 234 and the electrode 235 are formed. Specifically, first, the insulator layer 234 is formed between the power generation elements. Next, an electrode 235 is formed on the piezoelectric layers 113 and 123 and the insulator layer 234. Adjacent power generation elements are connected in series by the electrode 235.

  Next, as shown in FIG. 13D, the vibration member 101 is formed. In this way, a power generation device 230 including a plurality of power generation elements is obtained. The vibration member 101 may be formed by attaching a substrate on the electrode 235 and then etching the substrate. The vibration member 101 can also be formed by a plating method. For example, a thick film resist patterned with a high aspect ratio may be used as a mold, and after plating such as Ni or Cu, the thick film resist may be removed and formed.

  The power generation element and the power generation device of the present invention have been described above with examples. In the power generation element and the power generation device of the present invention, the vibration of the vibration member is not limited to the vibration due to the vibration of the base material. For example, a fluid may be arranged around the vibration member, and the vibration member may be vibrated by the reciprocating motion of the fluid. One such example is shown in FIG. The power generator 210 is fixed inside the pipe 241. A liquid 242 is disposed inside the conduit 241. The liquid 242 reciprocates due to external vibration or the like. As a result, the vibration member of the power generation apparatus 210 vibrates and power generation is performed.

[Control of polarization direction]
In the power generation element and the power generation device of the present invention, it is necessary to control the polarization direction of the piezoelectric layer. There is no limitation on the method of controlling the polarization direction of the piezoelectric layer, and a known method may be used.

  An example of a method for controlling the polarization direction is a method for controlling the polarization direction by applying an electric field to the formed piezoelectric layer (polling process). According to this method, the polarization direction 114 of the piezoelectric layer 113 and the polarization direction 124 of the piezoelectric layer 123 can be reversed as in the power generation element 100c of FIG. Specifically, after patterning the piezoelectric layer to form the piezoelectric layer 113 and the piezoelectric layer 123, different electrodes may be brought into contact with each other and an electric field applied in the opposite direction.

  Hereinafter, the result of having performed simulation about the electric power obtained by the power generation element will be described.

[Example 1]
In Example 1, the electric power obtained by the power generation element 100 of Embodiment 1 was simulated by the finite element method.

The vibration member 101 was assumed to be made of crystalline silicon. The vibration member 101 had a length of 825 μm, a cross section of 50 μm square, and a Young's modulus of 153 GPa. The piezoelectric layers 113 and 123 were assumed to be layers made of PZT. Each piezoelectric layer had a rectangular shape with a planar shape of 20 μm × 50 μm, a thickness of 3 μm, and a Young's modulus of 93 GPa. Each piezoelectric layer had a piezoelectric constant d ₃₁ of 130 pm / V, a piezoelectric constant d ₃₃ of 430 pm / V, and a relative dielectric constant of 800. It was assumed that an anisotropic conductive adhesive film having a thickness of 10 μm and a Young's modulus of 1 GPa was used for the conductive adhesive layer.

When an acceleration having an amplitude of 2 m / s ² and increasing or decreasing at a frequency different from the resonance frequency of the structure is applied to the power generation element having the above structure, a voltage of 16 μV is generated in each piezoelectric element, and a voltage of 32 μV is generated in one power generation element. Will occur. The two piezoelectric elements are connected in series, and the electrostatic capacity of the power generation element is 1.18 × 10 ⁻¹² F. Therefore, 1.21 × 10 ⁻²¹ W electric power can be obtained per one power generation element.

[Comparative Example 1]
In order to confirm the effect of the present invention, a simulation was performed on a conventional power generation element using the piezoelectric lateral effect. The simulation was performed for the power generation element 5 having the structure shown in FIG. The power generation element 5 includes a vibration member 6 disposed on the base member 8 and piezoelectric bodies 7 a and 7 b disposed on both ends of the vibration member 6 on the base member 8. As in Example 1, the vibration member 6 was assumed to be crystalline silicon having a length of 825 μm and a cross section of 50 μm square. The vibration member 6 is fixed to the base material 8 with an adhesive having a thickness of 10 μm. The piezoelectric bodies 7a and 7b have the same shape as the piezoelectric layer of Example 1 (planar shape is a rectangle of 20 μm × 50 μm and a thickness of 3 μm). The piezoelectric bodies 7a and 7b were assumed to be polarized in the direction of the polarization direction 9. As the physical property values of the constituent members, the same values as those used in the simulation of Example 1 were used.

When an acceleration that has an amplitude of 2 m / s ² and increases or decreases at a frequency different from the resonance frequency of the structure is applied to the power generation element of Comparative Example 1, a voltage of 1.1 μV is generated in each piezoelectric body. When the piezoelectric bodies 7a and 7b are connected in parallel, the capacitance becomes 4.72 × 10 ⁻¹² F. As a result, electric power of 5.71 × 10 ⁻²⁴ W is obtained per one power generation element.

  As described above, according to the simulation results, the power generation element of Example 1 can obtain approximately 210 times the power of the power generation element of Comparative Example 1. The resulting power can be increased by connecting a number of elements and matching the resonant frequency of the structure with the frequency of the vibration to be recovered.

  The present invention can be used for a power generation element and a power generation device using a piezoelectric body. There is no limitation in the field of application of the power generation element and power generation device of the present invention. Since the power generation element and power generation device of the present invention are small in size, they can be used as a power generation device for charging or an auxiliary power source for mobile devices such as mobile phones and music players. In that case, since electricity is generated simply by carrying the device when a person moves, it becomes possible to eliminate the need for charging or increase the charging interval.

  Moreover, it is possible to obtain electric power by attaching the power generation element or the power generation device of the present invention to various structures such as houses, buildings, and bridges, and vibrating objects such as automobile bodies and tires. Therefore, by using the power generation element or power generation device of the present invention as the power source of the sensor, sensors that do not require power supply can be installed in various places. For example, a plurality of sensors can be connected in a network and operated as a sensor system.

It is a top view which shows an example of the electric power generating element of this invention. It is (a) sectional drawing and (b) other sectional drawing of the electric power generation element shown in FIG. It is a figure which shows the operation state of the electric power generating element shown in FIG. It is a figure which shows an example of the circuit connected to the electric power generation element shown in FIG. It is sectional drawing which shows another example of the electric power generating element of this invention. It is a figure which shows an example of the circuit connected to the connection method of an electrode, and a power generation element about the power generation element shown in FIG. It is a figure which shows another example of the electric power generating element of this invention, and an example of the circuit connected to it. (A) And (b) is sectional drawing which shows the other example of the electric power generating element of this invention, respectively. It is sectional drawing which shows another example of the electric power generating element of this invention. It is sectional drawing which shows another example of the electric power generating element of this invention. It is process drawing which shows an example about the manufacturing method of the electric power generating apparatus of this invention. It is a figure which shows an example of the electrical wiring of the electric power generating apparatus of this invention. It is process drawing which shows another example about the manufacturing method of the electric power generating apparatus of this invention. It is a figure which shows an example in the case of generating electric power by the motion of the fluid. It is sectional drawing which shows the structure of the power generation element of the comparative example assumed by simulation. It is a figure which shows the function of a general piezoelectric element.

Explanation of symbols

100, 100a to 100g Power generation element 101 Vibration member 101a One end (fixed end)
101b The other end (free end)
102 Substrate 103a, 103b Electric wiring 105 direction (direction connecting the first piezoelectric layer and the second piezoelectric layer)
110, 110a First piezoelectric element 111 Electrode (first electrode)
112 electrodes (second electrode, fourth electrode)
113 First piezoelectric layer 114, 124 Polarization direction 120, 120a Second piezoelectric element 121 Electrode (third electrode)
123 Second piezoelectric layer 140 Circuit 141 Full wave rectifier circuit 142 Capacitor 182, 183 Buffer member 200 Weight 210, 230 Power generator 221 Wiring 222 Direction (direction connecting the first electrode and the third electrode)

Claims (13)

A first piezoelectric element including a first electrode, a first piezoelectric layer, and a second electrode, which are sequentially stacked on the substrate;
A second piezoelectric element including a third electrode, a second piezoelectric layer, and a fourth electrode, which are sequentially stacked on the substrate;
A vibration member,
One end of the vibrating member is fixed to the second and fourth electrodes,
The other end of the vibration member opposite to the one end can vibrate in a direction parallel to a direction connecting the first piezoelectric layer and the second piezoelectric layer,
The first piezoelectric layer is polarized in a direction parallel to a direction connecting the first electrode and the second electrode;
The power generation element, wherein the second piezoelectric layer is polarized in a direction parallel to a direction connecting the third electrode and the fourth electrode. The first piezoelectric layer and the second piezoelectric layer are polarized in the same direction;
One set of electrodes is connected among the set of electrodes including the first electrode and the third electrode, and the set of electrodes including the second electrode and the fourth electrode. The power generating element according to claim 1. The first piezoelectric layer and the second piezoelectric layer are polarized in the same direction;
The power generation element according to claim 1, wherein the first electrode and the fourth electrode are connected, and the second electrode and the third electrode are connected. The polarization direction of the first piezoelectric layer and the polarization direction of the second piezoelectric layer are opposite to each other;
The first electrode and the third electrode are connected;
The power generation element according to claim 1, wherein the second electrode and the fourth electrode are connected.   The power generation element according to claim 1, wherein the first and third electrodes are directly fixed on the base material.   The buffer member which can be deform | transformed with the vibration of the said vibration member is arrange | positioned between the said base material and the said 1st electrode, and between the said base material and the said 3rd electrode. 5. The power generation element according to any one of 4 above.   The power generating element according to claim 6, wherein another piezoelectric element using a piezoelectric body is formed in the middle of the buffer member. One or more other first piezoelectric elements are laminated between the base material and the first piezoelectric element,
The power generating element according to any one of claims 1 to 4, wherein one or more other second piezoelectric elements are stacked between the base material and the second piezoelectric element.   The power generating element according to any one of claims 1 to 8, wherein a weight made of a material having a specific gravity greater than that of the vibration member is fixed to the other end.   The power generation element according to any one of claims 1 to 9, wherein the first piezoelectric layer and the second piezoelectric layer are integrated to form one piezoelectric layer. A power generation device including a plurality of power generation elements formed on a substrate,
Each of the plurality of power generating elements is sequentially stacked on the base material, the first piezoelectric element including a first electrode, a first piezoelectric layer, and a second electrode sequentially stacked on the base material. A third piezoelectric element, a second piezoelectric element including a second piezoelectric layer and a fourth electrode, and a vibration member,
One end of the vibrating member is fixed to the second and fourth electrodes,
The other end of the vibration member opposite to the one end can vibrate in a direction parallel to a direction connecting the first piezoelectric layer and the second piezoelectric layer,
The first piezoelectric layer is polarized in a direction parallel to a direction connecting the first electrode and the second electrode;
The power generation apparatus, wherein the second piezoelectric layer is polarized in a direction parallel to a direction connecting the third electrode and the fourth electrode.   The power generation device according to claim 11, wherein the plurality of power generation elements are arranged so that directions connecting the first electrode and the third electrode are parallel to each other.   The power generation device according to claim 11 or 12, wherein two adjacent power generation elements are connected in series.

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