JP5887457B2 - Power generation element - Google Patents

Description

  The present invention relates to a power generation element, and more particularly to a technique for generating power by converting vibration energy into electric energy.

  In order to make effective use of limited resources, techniques for converting various forms of energy into electrical energy and taking them out have been proposed. One technique is to extract vibration energy by converting it into electrical energy. For example, in Patent Document 1 below, a piezoelectric element for power generation is formed by laminating layered piezoelectric elements, and the piezoelectric element for power generation is externally applied. There is disclosed a piezoelectric power generation element that generates power by vibrating it. Patent Document 2 discloses a power generation element having a micro electro mechanical system (MEMS) structure using a silicon substrate.

  The basic principle of these power generation elements is to cause periodic bending of the piezoelectric element due to vibration of the weight body, and to extract the electric charge generated based on the stress applied to the piezoelectric element to the outside. If such a power generation element is mounted on, for example, an automobile, a train, a ship, etc., vibration energy applied during transportation can be taken out as electric energy. It is also possible to generate electricity by attaching it to a vibration source such as a refrigerator or an air conditioner.

JP-A-10-243667 JP 2011-152010 A

  Conventionally proposed general power generation elements adopt a structure in which a weight body is supported by a cantilever beam with one end fixed, and the vertical vibration of this weight body causes periodic bending in the bridge portion. A method of generating electric charges by transmitting the bending to the piezoelectric element is adopted. In such a system, it is difficult to obtain sufficient power generation efficiency because only vibration energy that vibrates the weight body in the vertical direction can be used.

  For example, in transportation equipment such as automobiles, trains, and ships, force is applied from a random direction during operation, so in the case of a power generation element mounted on such transportation equipment, various directional components are included in the vibration of the weight body. Will be included. However, in the conventional power generation element described above, only one specific axial component of these vibration energies can be used for conversion. Therefore, conversion efficiency to electric energy is poor, and it is difficult to improve power generation efficiency. is there.

  Therefore, an object of the present invention is to provide a power generation element capable of obtaining high power generation efficiency by converting vibration energy containing various directional components into electric energy without waste.

(1) A first aspect of the present invention is a power generation element that generates power by converting vibration energy into electrical energy.
When defining a first axis and a second axis that intersect on a predetermined reference plane,
A first member extending from the root end to the tip along the first axis;
A second member connected to the tip of the first member and extending along a second axis;
A weight body connected directly or indirectly to the second member;
An apparatus housing for housing the first member, the second member, and the weight body;
A fixing portion for fixing the root end portion of the first member to the apparatus housing;
A lower layer electrode formed in a layer on at least the surface of the first member;
An upper electrode group consisting of a piezoelectric element formed in a layer on the surface of the lower electrode and a plurality of upper electrodes locally formed on the surface of the piezoelectric element;
A power generation circuit that rectifies the current generated based on the charges generated in the upper layer electrode and the lower layer electrode and extracts power,
Provided,
At least the first member has flexibility, and the weight body is connected to the fixing portion via the first member and the second member,
When an external force that vibrates the device casing is applied, the weight body is configured to vibrate within the device casing by at least the bending of the first member,
The piezoelectric element has the property of causing polarization in the thickness direction by the action of stress that expands and contracts in the layer direction,
The upper electrode group includes a tip side right side electrode and tip side left side electrode disposed in the vicinity of the tip of the first member, and a root end side right in the vicinity of the root end of the first member. It has a side electrode and the apical side left side electrode, each of these upper electrodes are arranged so as to extend along the first axis, to face the predetermined region of the lower electrode across the piezoelectric element And
When the first member defines a center line along the first axis and a right side and a left side with respect to the center line, the tip side right side electrode is positioned on the right side of the center line. The tip side left side electrode is placed on the left side of the center line so that it does not stick out on the right side of the center line. The root end side right side electrode is arranged on the right side of the center line so as not to protrude to the left side of the center line, and the root end side left side electrode is located on the left side of the center line. In addition, it is arranged so that it does not protrude to the right side of the center line.

(2) According to a second aspect of the present invention, in the power generation element according to the first aspect described above,
The first axis and the second axis are axes orthogonal on the reference plane;
The tip of the first member and the side of the second member are connected, and the first member and the second member are formed in a T shape near the connection portion.

(3) According to a third aspect of the present invention, in the power generation element according to the first or second aspect described above,
The fixing portion is configured by an annular structure disposed along the reference plane, and the first member, the second member, and the weight body are disposed in an inner region surrounded by the annular structure. ,
The distance between the inner surface of the annular structure and the facing surface of the first member and the distance between the inner surface of the annular structure and the facing surface of the second member are such that the first member or the first Even when excessive acceleration is applied such that the member 2 is damaged, the distance is set at a distance that can prevent the damage by restricting the excessive displacement of each part, and the annular structure controls the excessive displacement. It plays a role as a member.

(4) According to a fourth aspect of the present invention, in the power generation element according to the third aspect described above,
Even when the distance between the inner surface of the annular structure and the weight body is such that excessive acceleration that damages the first member or the second member is applied to the weight body, excessive displacement of each part The distance is set so that the damage can be avoided and the damage can be avoided.

(5) A fifth aspect of the present invention is to reverse the roles of the fixed portion and the weight body in the power generating element according to the first to fourth embodiments described above, to function as a fixed part in the power generation element fixing caused to function use members as the weight body, a weight member for functioning as a weight body to function as a fixed part in the power generation device, to secure the lower surface of the weight member on the upper surface of the bottom plate of the apparatus housing, The fixing member is suspended in a suspended state above the bottom plate of the apparatus housing in a state where no external force is applied.

(6) A sixth aspect of the present invention is the power generation element according to the first to fifth aspects described above,
A lower layer electrode is formed on the upper surface of the first member , and a piezoelectric element is formed on the upper surface of the lower layer electrode,
The upper layer electrode group has an upper layer electrode locally formed on the upper surface of the first member via the lower layer electrode and the piezoelectric element.

(7) According to a seventh aspect of the present invention, in the power generation element according to the first to fifth aspects described above,
The lower layer electrode is formed on the side surface together with the upper surface of the first member , and the piezoelectric element is formed on the surface of the lower layer electrode.
The upper layer electrode group has an upper layer electrode formed on the side surface of the first member via a lower layer electrode and a piezoelectric element.

(8) The eighth aspect of the present invention is the power generating element according to the first to fifth aspects described above,
The lower layer electrode is formed on the side surface together with the upper surface of the first member , and the piezoelectric element is formed on the surface of the lower layer electrode.
The upper layer electrode group has an upper layer electrode formed through a lower layer electrode and a piezoelectric element from the upper surface to the side surface of the first member .

(9) According to a ninth aspect of the present invention, in the power generation element according to the first to eighth aspects described above,
The first member and the second member are constituted by an integral structure obtained by processing the same plate-like member.

(10) According to a tenth aspect of the present invention, in the power generation element according to the first to ninth aspects described above,
The power generation circuit includes a capacitive element and a positive charge rectifying element having a forward direction from each upper layer electrode toward the positive electrode side of the capacitive element to guide the positive charge generated in each upper electrode to the positive electrode side of the capacitive element; A negative charge rectifying element whose forward direction is from the negative electrode side of the capacitive element to each upper layer electrode in order to guide the negative charge generated in each upper layer electrode to the negative electrode side of the capacitive element, and converts from vibration energy The electric energy is smoothed and supplied by a capacitive element.

In addition, in the embodiments described later, various reference forms are described in addition to the first to tenth aspects described above.

  Here, the outlines of typical reference forms (a) to (f) are described below.

(a) The reference mode (a) disclosed in the present application is the power generation element according to each mode described above,
Between the second plate-like bridge portion and the weight body, a third plate-like bridge portion to a K-th plate-like bridge portion (where K ≧ 3) are provided,
The tip of the i-th plate-like bridge portion (where 1 ≦ i ≦ K−1) is connected directly or indirectly to the root end of the (i + 1) -th plate-like bridge portion, and the K-th plate-like bridge The tip of the part is connected directly or indirectly to the weight body,
The jth plate-like bridge portion (where 1 ≦ j ≦ K) extends along the jth longitudinal axis parallel to the Y axis when j is an odd number, and parallel to the X axis when j is an even number. Extending along the jth longitudinal axis.

(b) The reference aspect (b) disclosed in the present application is the power generation element according to the reference aspect (a) described above.
The tip of the i-th plate bridge portion (where 1 ≦ i ≦ K−1) and the root end portion of the (i + 1) -th plate bridge portion are connected via the i-th intermediate connection portion. , The tip of the Kth plate-like bridge portion and the weight body are connected via the weight connection portion,
The i-th intermediate connection portion has a flange structure portion protruding outward from the side surface of the tip portion of the i-th plate-like bridge portion, and the weight connection portion is provided at the tip portion of the K-th plate-like bridge portion. It has an eaves structure part protruding outward from the side surface.

(c) The reference mode (c) disclosed in the present application is the power generation element according to the above-described reference modes (a) and (b).
The central position where the structure from the root end of the first plate-like bridge portion to the tip of the K-th plate-like bridge portion forms a spiral path, and the weight body is surrounded by the spiral path It is made to arrange in.

(d) The reference aspect (d) disclosed in the present application is the power generation element according to the reference aspects (a) to (c) described above.
A lower layer electrode, a piezoelectric element, and an upper layer electrode group are also provided on the surfaces of the third plate-shaped bridge portion to the K-th plate-shaped bridge portion, and the i-th plate-shaped bridge portion (where 1 ≦ i ≦ K−1). The i-th upper layer electrode group formed on the i-th plate-shaped bridge portion is disposed in the vicinity of the root end portion of the i-th plate-shaped bridge portion, and the vicinity of the tip portion of the i-th plate-shaped bridge portion. And the power generation circuit rectifies the current generated based on the charges generated in the individual upper layer electrodes and the lower layer electrodes and takes out the electric power. is there.

(e) The reference aspect (e) disclosed in the present application is the power generation element according to the reference aspects (a) to (d) described above.
The fixed portion is constituted by an annular structure, and the first plate-shaped bridge portion to the K-th plate-shaped bridge portion and the weight body are arranged in the inner region surrounded by the annular structure. It is a thing.

(f) The reference aspect (f) disclosed in the present application is the power generation element according to the reference aspect (e) described above,
The roles of the fixed part and the weight body are reversed, the annular structure functioning as the fixed part in the power generation element is functioned as the weight body, and the plate-shaped body functioning as the weight body in the power generation element is fixed. In order to function as a part, the lower surface of the plate-like body is fixed to the upper surface of the bottom plate of the device housing, and the annular structure is suspended in a suspended state above the bottom plate of the device housing in a state where no external force is applied. It is what I did.

In the power generating element according to the present invention, since the first member extending along the first axis and the second member extending along the second axis intersect each other, at least the root end of the first member Effective stress can be generated at the tip and the tip. In addition, since the generated charge is taken out from the left and right of the first member and the left and right of the root portion, the charge can be taken out from the stress-concentrated portion and includes components in each axial direction. Vibration energy can be converted into electric energy without waste, and high power generation efficiency can be obtained.

It is the top view (figure (a)) and side view (figure (b)) of the basic structure which comprise the electric power generating element which concerns on the 1st Embodiment of this invention. FIG. 1 is a plan view (FIG. 1 (a)) showing a state in which the weight body 30 of the basic structure produces a displacement Δx (+) in the X-axis positive direction and a displacement Δz (+) in the Z-axis positive direction. It is a side view (figure (b)) which shows the state when this occurs. It is the top view (figure (a)) of the electric power generation element which concerns on the 1st Embodiment of this invention, and the sectional side view (figure (b)) which cut | disconnected this at the YZ plane. 4 is a table showing polarities of charges generated in upper layer electrodes E11 to E23 when displacement in the direction of each coordinate axis occurs in the weight body 30 of the power generating element shown in FIG. 3. It is a circuit diagram which shows the specific structure of the electric power generation circuit 60 used for the electric power generation element shown in FIG. It is a top view which shows the modification of the electric power generating element shown in FIG. It is a table | surface which shows the polarity of the electric charge which arises in each upper-layer electrode E31-E33 when the displacement of each coordinate-axis direction arises in the weight body 30 of the electric power generation element shown in FIG. It is a front sectional view showing a variation of the arrangement mode of the upper layer electrode in the power generation element according to the present invention. FIG. 4 is a plan view (FIG. (A)) of a basic structure 100 constituting a power generating element according to a second embodiment of the present invention and a side sectional view (FIG. (B)) of cutting this along a YZ plane. It is the top view (figure (a)) of the electric power generation element which concerns on the 2nd Embodiment of this invention, and the sectional side view (figure (b)) which cut | disconnected this at the YZ plane. FIG. 10 is a plan view showing an expansion / contraction state of each upper layer electrode formation position when the weight body 150 of the basic structure body 100 shown in FIG. 9 generates a displacement Δx (+) in the X-axis positive direction. FIG. 10 is a plan view showing a stretched state of each upper layer electrode formation position when the weight body 150 of the basic structure 100 shown in FIG. 9 generates a displacement Δy (+) in the Y-axis positive direction. FIG. 10 is a plan view showing a stretched state of each upper layer electrode formation position when the weight body 150 of the basic structure 100 shown in FIG. 9 generates a displacement Δz (+) in the positive direction of the Z axis. 11 is a table showing polarities of electric charges generated in upper layer electrodes Ex1 to Ez4 when displacement in the direction of each coordinate axis occurs in the weight body 150 of the power generation element shown in FIG. 10. It is a circuit diagram which shows the specific structure of the electric power generation circuit 500 used for the electric power generation element shown in FIG. It is a top view which shows the structure of the basic structure of the electric power generating apparatus using 4 sets of electric power generating elements shown in FIG. It is a top view which shows the structure of the basic structure of the electric power generating apparatus which concerns on the modification of the electric power generating apparatus shown in FIG. FIG. 11 is a plan view (FIG. (A)) showing a structure of a basic structure of a power generation element according to a modification of the power generation element shown in FIG. 10 and a side sectional view (FIG. (B)) of cutting this along a YZ plane. In the basic structure of the power generating element shown in FIG. 10 (FIG. (A)) and the basic structure of the power generating element shown in FIG. 18 (FIG. (B)), the weight body 150 is displaced in the X-axis positive direction Δx (+). It is a stress distribution figure which shows the magnitude | size of the stress which arises in each plate-shaped bridge part when producing | generating. For the basic structure of the power generating element shown in FIG. 10 (FIG. (A)) and the basic structure of the power generating element shown in FIG. 18 (FIG. (B)), the weight body 150 is displaced in the positive Y-axis direction Δy (+). It is a stress distribution figure which shows the magnitude | size of the stress which arises in each plate-shaped bridge part when producing | generating. For the basic structure of the power generation element shown in FIG. 10 (FIG. (A)) and the basic structure of the power generation element shown in FIG. 18 (FIG. (B)), the weight 150 is displaced in the positive direction of the Z axis Δz (+). It is a stress distribution figure which shows the magnitude | size of the stress which arises in each plate-shaped bridge part when producing | generating. FIG. 19 is a plan view (FIG. (A)) showing a structure of a basic structure of a power generation element according to a modification of the power generation element shown in FIG. 18 and a side sectional view (FIG. (B)) of cutting this along the YZ plane. It is a top view which shows the structure of the basic structure of the electric power generating element which concerns on another modification of the electric power generating element shown in FIG. FIG. 18 is a plan view (FIG. (A)) showing a structure of a basic structure of a power generation element according to still another modified example of the power generation element shown in FIG. 18 and a side sectional view (FIG. (B)) taken along the YZ plane. is there. FIG. 23 is a plan view (FIG. (A)) showing a structure of a basic structure of a power generation element according to a modification of the power generation element shown in FIG. 22 and a side cross-sectional view (FIG. (B)) taken along the YZ plane.

  Hereinafter, the present invention will be described based on the illustrated embodiments.

<<< §1. First embodiment (two-axis power generation type) >>
FIG. 1 is a plan view (upper view (a)) and a side view (lower view (b)) of a basic structure constituting a power generating element according to the first embodiment of the present invention. As shown in FIG. 1A, this basic structure is composed of a fixed portion 10, a plate-like bridge portion 20, and a weight body 30. The side view of FIG. 1B shows a state in which the lower surface of the fixing portion 10 is fixed to the upper surface of the bottom plate 40 of the apparatus housing. Here, for the sake of convenience, detailed illustration of the apparatus housing is omitted, and in FIG. 1B, only a part of the bottom plate 40 is shown by hatching, but in practice, the entire basic structure is shown. An apparatus housing is provided for accommodating.

  The plate-like bridge portion 20 has a left end in the figure fixed by a fixing portion 10 and a weight body 30 connected to the right end. The plate-like bridge portion 20 functions as a cantilever and plays a role of holding the weight body 30 in a suspended state above the bottom plate 40 of the apparatus housing. Hereinafter, the end (left end in the figure) on the fixed part 10 side of the plate-like bridge part 20 is referred to as a root end part, and the end on the weight body 30 side (right end in the figure) is referred to as a tip part.

  Since the plate-like bridge portion 20 has flexibility, it is bent by the action of external force. For this reason, when a vibration is applied to the apparatus housing from the outside, a force is applied to the weight body 30 by this vibration energy, and this force acts on the tip of the plate-like bridge portion 20. Since the root end portion of the plate-like bridge portion 20 is fixed, the plate-like bridge portion 20 is bent, and the weight body 30 vibrates in the apparatus housing.

  Here, for convenience of explaining the vibration direction, the origin O is set at the center of gravity of the weight body 30 in a state where the apparatus housing is stationary, and an XYZ three-dimensional coordinate system is defined as shown. That is, in the plan view of FIG. 1 (a), the X axis is defined below the figure, the Y axis is defined on the right side of the figure, and the Z axis is defined vertically above the page. In the side view of FIG. 1 (b), the Z-axis is defined above the figure, the Y-axis is defined on the right side of the figure, and the X-axis is defined vertically above the page. In the subsequent drawings in the present application, the coordinate axes are defined in the same direction.

  For convenience of explanation, it is assumed that the apparatus housing is attached to a vibration source (for example, a vehicle) in such a direction that the XY plane of the three-dimensional coordinate system described above is a horizontal plane and the Z axis is a vertical axis. . Therefore, in the present application, regarding the basic structure, generally, “up” means the positive direction of the Z axis, and generally “down” means the negative direction of the Z axis (of course, “upward in the figure”). "Or" downward in the figure "means above or below in the figure).

  FIG. 2A is a plan view showing a deformed state when the weight body 30 generates the displacement Δx (+) in the positive direction of the X-axis with reference to the position of the fixed portion 10 in the basic structure shown in FIG. FIG. Such displacement occurs when acceleration in the positive direction of the X-axis acts on the weight body 30. Since the weight body 30 is displaced downward in the drawing, the upper side in the drawing of the plate-like bridge portion 20 extends in the Y-axis direction, and the lower side in the drawing of the plate-like bridge portion 20 shrinks in the Y-axis direction. In other words, the upper portion in the drawing extends in the Y-axis direction from the center line indicated by the broken line in the drawing, and the lower portion in the drawing shrinks in the Y-axis direction.

  FIG. 2A shows a state when a displacement Δx (+) in the X-axis positive direction occurs. When the displacement Δx (−) in the X-axis negative direction occurs, the weight body 30 is shown in FIG. Accordingly, the expansion / contraction state of each part of the plate-like bridge portion 20 is an inversion of the state shown in FIG. Therefore, when vibration energy having a vibration component in the X-axis direction is applied to the device casing, the shape of the basic structure is deformed while alternately repeating the state shown in FIG. 2 (a) and its inverted state. The weight body 30 vibrates in the X-axis direction (horizontal direction) within the apparatus housing.

  On the other hand, FIG. 2B shows a deformation state when the weight body 30 is displaced in the positive direction of the Z axis Δz (+) with respect to the position of the fixed portion 10 in the basic structure shown in FIG. FIG. Such displacement occurs when acceleration in the positive direction of the Z-axis acts on the weight body 30. Since the weight body 30 is displaced upward in the drawing, the upper surface side of the plate-like bridge portion 20 in the drawing is contracted in the Y-axis direction, and the lower surface side of the plate-like bridge portion 20 in the drawing is extended in the Y-axis direction. In other words, the upper layer portion of the plate-like bridge portion 20 contracts in the Y-axis direction, and the lower layer portion extends in the Y-axis direction.

  FIG. 2B shows a state when a displacement Δz (+) in the positive direction of the Z-axis is generated. When the displacement Δz (−) in the negative direction of the Z-axis is generated, the weight body 30 is shown in FIG. Therefore, the expansion / contraction state of each part of the plate-like bridge portion 20 is the reverse of the state shown in FIG. 2 (b). Therefore, when vibration energy having a vibration component in the Z-axis direction is applied to the device casing, the shape of the basic structure is deformed while alternately repeating the state shown in FIG. 2 (b) and its inverted state. The weight body 30 vibrates in the Z-axis direction (vertical direction) within the apparatus housing.

  Here, the illustration of the deformation state when the displacements Δy (+) and Δy (−) in the Y-axis direction occur is omitted. Of course, when acceleration in the Y-axis direction acts on the weight body 30, the plate-like bridge portion 20 extends or contracts in the Y-axis direction as a whole, and the weight body 30 is displaced in the Y-axis direction. It will be. However, if the amount of applied vibration energy is the same, the amounts of displacements Δy (+) and Δy (−) in the Y-axis direction are the amounts of displacements Δx (+) and Δx (−) in the X-axis direction and the Z-axis direction. Is smaller than the amount of displacement Δz (+), Δz (−). That is, the amount of expansion / contraction of the plate-like bridge portion 20 caused by vibration energy in the Y-axis direction is smaller than the amount of expansion / contraction of the plate-like bridge portion 20 caused by vibration energy in the X-axis or Z-axis direction.

  This is performed by a deformation operation in which the vibration in the X-axis direction and the vibration in the Z-axis direction of the weight body 30 bend the plate-like bridge portion 20 in a predetermined direction as shown in FIGS. 2 (a) and 2 (b). On the other hand, the vibration in the Y-axis direction is thought to be due to the low mechanical deformation efficiency because it is performed by a deformation operation that stretches or compresses the plate-like bridge portion 20 as a whole.

  For this reason, the power generation element according to the first embodiment is designed as a two-axis power generation element that generates power based on vibration in the X-axis direction and vibration in the Z-axis direction of the weight body 30. Therefore, no consideration is given to vibration in the Y-axis direction. Of course, power generation is possible even when vibration energy in the Y-axis direction is applied, but the power generation efficiency is considerably lower than that when vibration energy in the X-axis or Z-axis direction is applied. Become.

  In the case of the embodiment shown here, the basic structure composed of the fixing portion 10, the plate-like bridge portion 20, and the weight body 30 is configured by an integral structure cut out from the silicon substrate. In the case of this embodiment, the plate-like bridge portion 20 has a beam structure having a width in the X-axis direction of 1 mm, a length in the Y-axis direction of 4 mm, and a thickness in the Z-axis direction of about 0.5 mm. The weight body 30 has a width in the X-axis direction of 5 mm, a width in the Y-axis direction of 3 mm, a thickness in the Z-axis direction of 0.5 mm, and the fixed portion 10 has a width in the X-axis direction of 5 mm and the Y-axis direction. The width is 2 mm, and the thickness in the Z-axis direction is 1 mm.

  Of course, the dimension of each part can be set arbitrarily. In short, the plate-like bridge portion 20 may be set to a size suitable for having flexibility that can be deformed as shown in FIG. 2, and the weight body 30 is formed by the plate-like bridge by vibration energy from the outside. The dimension may be set to a dimension having a mass sufficient to cause the deformation of the part 20 as shown in FIG. 2, and the fixing part 10 is a dimension capable of firmly fixing the entire basic structure to the bottom plate 40 of the apparatus housing. Should be set.

  As shown in FIG. 2 (b), the thickness of the fixing portion 10 is set to be larger than the thickness of the plate-like bridge portion 20 and the weight body 30, and the weight body 30 is suspended in the apparatus housing. Ensure a space that can vibrate in the vertical direction. As described above, this basic structure is housed in the apparatus housing. However, the inner wall surface of the apparatus housing (for example, the upper surface of the bottom plate 40 shown in FIG. 2B), the weight body 30, and the like. Is preferably set to a predetermined value so that the inner wall surface of the apparatus housing functions as a control member that limits excessive displacement of the weight body 30. Then, even when excessive acceleration (acceleration that damages the plate-like bridge portion 20) is applied to the weight body 30, the excessive displacement of the weight body 30 can be limited, and the plate-like bridge portion. The situation where 20 is damaged can be avoided. However, if the gap size is too narrow, it will be affected by air damping and power generation efficiency will be reduced.

  As described above, the structure and the deformation operation of the basic structure that is a component of the power generation element according to the first embodiment have been described with reference to FIGS. 1 and 2. , Constructed by adding several elements.

  FIG. 3A is a plan view of the power generating element according to the first embodiment, and FIG. 3B is a side sectional view of the power generating element cut along the YZ plane. As shown in the side sectional view of FIG. 3 (b), the upper surface of the basic structure (fixing portion 10, plate-like bridge portion 20, weight body 30) shown in FIG. E0 is formed, and a layered piezoelectric element 50 is formed on the entire upper surface thereof. On the upper surface of the piezoelectric element 50, an upper layer electrode group including a plurality of locally formed upper layer electrodes is formed.

  In the case of the embodiment shown here, the upper electrode group is composed of six upper electrode electrodes E11 to E23 (the hatching in the figure is given to clearly show the electrode formation region, as shown in FIG. 3 (a)). , Not showing a cross section). In the side cross-sectional view of FIG. 3B, only the upper layer electrodes E12 and E22 located on the YZ cut surface appear. 3 (a) is a plan view of the power generation element as viewed from above, so that the piezoelectric element 50 covering the entire surface of the basic structure can be seen. For convenience, FIG. 3 (a) The positions of the fixed portion 10, the plate-like bridge portion 20, and the weight body 30 are indicated by parenthesized symbols.

  Here, among the six upper layer electrodes E11 to E23 shown in FIG. 3 (a), the three electrodes E11, E12, E13 formed on the weight body 30 side are called weight body side electrode groups. The three electrodes E21, E22, E23 formed on the fixed portion 10 side are referred to as a fixed portion side electrode group. Further, for the weight side electrode group, the electrode E12 disposed in the center is referred to as a center electrode, and the electrodes E11 and E13 disposed on both sides thereof are referred to as a right side electrode and a left side electrode, respectively. Similarly, with respect to the fixed portion side electrode group, the electrode E22 disposed in the center is referred to as a center electrode, and the electrodes E21 and E23 disposed on both sides thereof are referred to as a right side electrode and a left side electrode, respectively.

  Note that the terms “right side” and “left side” in the present application are used to distinguish a pair of electrodes arranged on both sides of the central electrode from each other. It means right and left when the top surface is viewed from the root end side. Of course, when the top surface of the plate-like bridge part is viewed from the tip side, the left and right will be reversed, but in this application, always the left and right when viewing the top surface of the plate-like bridge part from the root end side, We will use the words “right side” and “left side”.

  In the case of the embodiment shown here, the basic structure (fixing part 10, plate-like bridge part 20, weight body 30) is constituted by a silicon substrate. The lower layer electrode E0 and the upper layer electrodes E11 to E23 may be formed using a general conductive material such as metal. In the case of the example shown here, the lower layer electrode E0 and the upper layer electrodes E11 to E23 are formed by a thin metal layer (a metal layer comprising two layers of a titanium film and a platinum film) having a thickness of about 300 nm. On the other hand, as the piezoelectric element 50, a thin film of PZT (lead zirconate titanate) or KNN (potassium sodium niobate) may be used. In the case of the embodiment shown here, a thin-film piezoelectric element having a thickness of about 2 μm is formed.

  As shown in FIG. 3 (b), this power generation element further includes a power generation circuit 60. In FIG. 3B, the power generation circuit 60 is shown as a simple block, but a specific circuit diagram will be described later. As shown in the figure, wiring is provided between the power generation circuit 60 and the lower layer electrode E0 and the six upper layer electrodes E11 to E23, and the charges generated in the upper layer electrodes E11 to E23 are routed through the wiring. Then, it is taken out by the power generation circuit 60. Actually, each wiring can be formed by the conductive pattern formed on the upper surface of the piezoelectric element 50 together with the upper layer electrodes E11 to E23. In addition, when the basic structure is constituted by a silicon substrate, the power generation circuit 60 can be formed on the silicon substrate (for example, the fixed portion 10).

  In FIG. 3, the device casing is not shown (the bottom plate 40 shown in FIG. 3 (b) constitutes a part of the device casing). The entire structure shown in (2) is accommodated in a device housing (not shown).

  After all, the power generation element according to the first embodiment is a power generation element having a function of generating power by converting vibration energy into electric energy, and has a predetermined longitudinal axis (in the illustrated example, the Y axis). ), A flexible plate-like bridge portion 20, a weight body 30 connected to one end (tip portion) of the plate-like bridge portion 20, and the plate-like bridge portion 20 and the weight body 30. , A fixing portion 10 for fixing the other end (root end portion) of the plate-like bridge portion 20 to the device case (in the illustrated example, the upper surface of the bottom plate 40), and the plate-like bridge portion 20 A lower layer electrode E0 formed in a layer on the surface of the lower layer electrode, a piezoelectric element 50 formed in a layer on the surface of the lower layer electrode E0, and a plurality of upper layer electrodes E11 to 11 formed locally on the surface of the piezoelectric element 50 Upper electrode group consisting of E23, upper electrode E11-E23 and lower electrode E A generator circuit 60 for taking out the power by rectifying a current generated on the basis of the charge generated in, will be provided with a.

  As described above, in the power generating element having such a structure, when an external force that vibrates the apparatus housing acts, the weight body 30 vibrates within the apparatus housing due to the bending of the plate-like bridge portion 20. Then, the bending of the plate-like bridge portion 20 is transmitted to the piezoelectric element 50, and the piezoelectric element 50 is similarly bent. Here, since the piezoelectric element 50 has a property of causing polarization in the thickness direction by the action of stress that expands and contracts in the layer direction, electric charges are generated on the upper and lower surfaces thereof. The generated charges are taken out from the upper layer electrodes E11 to E23 and the lower layer electrode E0.

  In the case of the embodiment shown here, when a stress extending in the layer direction is applied, a positive charge is generated on the upper surface side, and a negative charge is generated on the lower surface side. Conversely, when a stress contracting in the layer direction is applied, a negative charge is generated on the upper surface side. A piezoelectric element 50 that generates a positive charge on the side is used. Of course, some piezoelectric elements have a polarization characteristic opposite to this, and the power generation element according to the present invention may use any piezoelectric element having any polarization characteristic.

  Next, let's look at the specific power generation operation of this power generation element. In the case of the embodiment shown in FIG. 3 (a), the upper electrode group includes weight body side electrode groups E11 to E13 arranged in the vicinity of the connection portion of the plate bridge portion 20 to the weight body 30, and the plate bridge portion. The fixed portion side electrode groups E21 to E23 are arranged in the vicinity of the connecting portion with the 20 fixed portions 10. The weight body side electrode group includes three types of electrodes, ie, the center electrode E12, the right side electrode E11, and the left side electrode E13, and the fixed part side electrode group also includes the center electrode E22, the right side electrode E21, and the left side electrode. It is comprised by three types of electrodes called E23.

  The six upper layer electrodes E11 to E23 are all arranged so as to extend along the longitudinal axis (Y axis) of the plate-like bridge portion 20, and face the predetermined region of the lower layer electrode E0 with the piezoelectric element 50 interposed therebetween. ing. In other words, although the lower layer electrode E0 and the piezoelectric element 50 are common, the six upper layer electrodes E11 to E23 are locally arranged individually, so that each of the six individual power generators is provided. It is arranged at a specific position.

  Here, the center electrodes E12 and E22 are positions of the center line along the longitudinal axis (Y axis) on the upper surface side of the plate-like bridge portion 20 (the position of the line translated from the Y axis to the upper surface of the piezoelectric element 50). ), And an electrode provided with the intention of efficiently extracting charges when the weight body 30 vibrates in the Z-axis direction.

  The right side electrode E11 is disposed on one side of the central electrode E12 (right side when viewed from the root end side), and the left side electrode E13 is the other side (root end) of the central electrode E12. It is arranged on the left side) when viewed from the section side. Similarly, the right side electrode E21 is disposed on one side of the central electrode E22 (right side when viewed from the root end side), and the left side electrode E23 is disposed on the other side (root) of the central electrode E22. It is arranged on the left side when viewed from the end side. Each of these side electrodes is an electrode that is intended to efficiently extract electric charges when the weight body 30 vibrates in the X-axis direction.

  FIG. 4 shows the electric charge generated in the upper layer electrodes E11 to E23 and the lower layer electrode E0 when displacement in the coordinate axis direction occurs in the weight body 30 with the lower layer electrode E0 as a common electrode in the power generation element shown in FIG. It is a table | surface which shows polarity. The sign “+” in the table indicates the generation of positive charge, and the sign “−” indicates the generation of negative charge. Further, the symbol “0” indicates that no charge is generated or that a small amount of charge is generated as compared with the case indicated by the symbols “+” and “−”. Practically, the generated charge in the column corresponding to the code “0” is not a significant amount, and will be ignored in the following description.

  When displacement in the direction of each coordinate axis occurs in the weight body 30, the plate-like bridge portion 20 bends as shown in FIGS. 2 (a) and 2 (b). On the other hand, as described above, the piezoelectric element 50 has a positive charge on the upper surface side and a negative charge on the lower surface side when stress extending in the layer direction is applied, and a negative charge and lower surface on the upper surface side when stress contracting in the layer direction is applied. It has a polarization characteristic in which a positive charge is generated on the side. In light of these points, it can be easily understood that the table shown in FIG. 4 is obtained.

  For example, when a displacement Δx (+) in the positive direction of the X-axis occurs, deformation as shown in FIG. 2A occurs, so that the piezoelectric elements immediately below the right side electrodes E11 and E21 contract in the longitudinal direction, Negative charges are generated in the side electrodes E11 and E21. On the other hand, the piezoelectric elements directly under the left side electrodes E13 and E23 extend in the longitudinal direction, and positive charges are generated in the left side electrodes E13 and E23. At this time, the piezoelectric elements directly below the center electrodes E12 and E22 arranged on the center line are expanded in half and contracted, so that the generated charges are canceled and no charges are generated in the center electrodes E12 and E22. On the other hand, the lower layer electrode E0 generates charges having the opposite polarity to the charges generated in the upper layer electrodes E11, E13, E21, and E23, but the sum of the generated charges of these upper layer electrodes is 0. Therefore, the generated charge of the lower layer electrode E0 is also zero.

  Further, when a displacement Δz (+) in the positive direction of the Z-axis occurs, deformation as shown in FIG. 2B occurs, so that all the piezoelectric elements immediately below the six upper layer electrodes E11 to E23 are in the longitudinal direction. And the negative charge is generated in all upper layer electrodes. On the other hand, in the lower electrode E0, a charge (positive charge) having a reverse polarity equal to the sum of charges (negative charges) generated in the upper layer electrodes E11 to E23 is generated. In the table of FIG. 4, the symbol “++++++” written in the column of the lower layer electrode E0 in the row of displacement Δz (+) indicates such a state.

  On the other hand, when the displacement Δy (+) in the Y-axis positive direction occurs, all the piezoelectric elements immediately below the six upper layer electrodes E11 to E23 extend in the longitudinal direction, so that positive charges are generated in all the upper layer electrodes. However, as described above, the amount of displacement Δy (+) in the Y-axis direction when the acceleration in the Y-axis direction is applied to the weight body 30 is the amount in the X-axis direction when the acceleration in the X-axis direction is applied. Since the amount of displacement Δx (+) and the amount of displacement Δz (+) in the Z-axis direction when an acceleration in the Z-axis direction is applied are small, the amount of positive charge generated is also small. Therefore, in the table of FIG. 4, the sign “0” is written in all Δy (+) columns to indicate that significant power generation is not performed.

  In the table of FIG. 4, the charge generated in each upper electrode when the displacement Δx (+), Δy (+), Δz (+) in the positive direction of each coordinate axis is generated with respect to the weight body 30 is shown. As shown, when displacements Δx (−), Δy (−), and Δz (−) in the negative direction of each coordinate axis occur, a result obtained by reversing the sign of the table in FIG. 4 is obtained. Normally, when vibration energy is applied from the outside, the weight body 30 vibrates within the apparatus housing, and therefore, the sign of the table shown in FIG. 4 is inverted in synchronization with the period of the vibration, The amount of occurrence will also increase or decrease periodically.

  Actually, since the vibration energy given from the outside has components in the coordinate axis directions in the XYZ three-dimensional coordinate system, the displacement of the weight body 30 is Δx (±), Δy (±), Δz (± ), And will change from moment to moment. Therefore, for example, when the displacements Δx (+) and Δz (+) occur simultaneously, both positive charges and negative charges are generated in the upper layer electrodes E13 and E23 as shown in the table of FIG. Therefore, some of the charges generated in the upper layer electrodes E13 and E23 are canceled out and cannot be taken out effectively.

  Thus, although 100% efficient power generation is not necessarily performed depending on the vibration mode of the weight body 30, the vibration energy of the weight body 30 in the X-axis direction and the Z-axis direction of the weight body 30 as a whole Both vibration energy and power can be extracted. As described above, the power generation using the biaxial component of the vibration energy of the weight body 30 is a feature of the power generation element according to the first embodiment of the present invention, and such a feature. Thus, the object of converting vibration energy containing various directional components into electrical energy as much as possible and obtaining high power generation efficiency is achieved.

  The power generation circuit 60 plays a role of rectifying a current generated based on the charges generated in the upper layer electrodes E11 to E23 and the lower layer electrode E0 to extract electric power. In the case of the embodiment shown here, the lower layer electrode E0 serves to ensure the reference potential as a common electrode. Therefore, in actuality, the current flowing from the upper layer electrodes E11 to E23 and the current flowing to the upper layer electrodes E11 to E23 are It may be collected separately and stored.

  FIG. 5 is a circuit diagram showing a specific configuration of the power generation circuit 60 used in the power generation element shown in FIG. Here, P11 to P23 indicate a part of the piezoelectric element 50, and correspond to portions located directly below the upper layer electrodes E11 to E23, respectively. Further, E0 indicated by a white circle on the circuit diagram corresponds to the lower layer electrode, and E11 to E23 correspond to the upper layer electrode. D11 (+) to D13 (−) are rectifying elements (diodes), and each rectifying element to which a sign (+) is attached plays a role of taking out a positive charge generated in each upper layer electrode. Each of the rectifying elements marked with serves to take out a negative charge generated in each upper layer electrode. Similarly, D0 (+) and D0 (−) are also rectifying elements (diodes) and play a role of extracting positive and negative charges generated in the lower layer electrode E0.

  On the other hand, Cf is a smoothing capacitive element (capacitor). The positive charge taken out is supplied to the positive terminal (upper terminal in the figure) and the negative charge taken out to the negative terminal (lower terminal in the figure). Is supplied. As described above, since the amount of electric charge generated by the vibration of the weight body 30 increases and decreases in a cycle corresponding to the vibration, the current flowing through each rectifying element becomes a pulsating flow. The capacitive element Cf plays a role of smoothing the pulsating flow. When the vibration of the weight body 30 is stable and steady, the impedance of the capacitive element Cf can be almost ignored.

  ZL connected in parallel to the capacitive element Cf indicates a load of a device that receives supply of electric power generated by the power generation element. In order to improve the power generation efficiency, it is preferable to match the impedance of the load ZL with the internal impedance of the piezoelectric element 50. Therefore, when a device to be supplied with power is assumed in advance, it is preferable to design the power generating device by adopting a piezoelectric element having an internal impedance matched with the impedance of the load ZL of the device.

  Eventually, the power generation circuit 60 is directed from the upper layer electrodes E11 to E23 toward the positive electrode side of the capacitive element Cf in order to guide the positive charges generated in the capacitive element Cf and the upper layer electrodes E11 to E23 to the positive electrode side of the capacitive element Cf. Rectifier elements D11 (+) to D23 (+) for positive charge with the forward direction being in the forward direction and from the negative electrode side of the capacitive element Cf in order to guide the negative charges generated in the upper layer electrodes E11 to E23 to the negative electrode side of the capacitive element Cf Negative charge rectifying elements D11 (−) to D23 (−) whose forward direction is toward each of the upper layer electrodes E11 to E23, and the electric energy converted from vibration energy is smoothed by the capacitive element Cf. The function of supplying to the load ZL is fulfilled.

  As can be seen from the circuit diagram of FIG. 5, the load ZL includes positive charges extracted by the positive charge rectifier elements D11 (+) to D13 (+) and negative charge rectifier elements D11 (−). The negative charge taken out at ~ D13 (-) is supplied. Therefore, in principle, the most efficient power generation is possible if the total amount of positive charges and the total amount of negative charges generated in the upper layer electrodes E11 to E23 are equal at each moment. In other words, when the total amount of positive charges and the total amount of negative charges generated at a certain moment is unbalanced, only the equal amount of both is used as power by the load ZL.

  Of course, in practice, the electric charge generated in the piezoelectric element is temporarily stored in the smoothing capacitor element Cf, so that the behavior of the actual power generation operation is not an instantaneous phenomenon but a phenomenon that takes a time average. In order to perform accurate analysis, complicated parameter settings are required. However, as a general theory, it is preferable for efficient power generation that the total amount of positive charges and the total amount of negative charges generated in the upper layer electrodes E11 to E23 are equal at each moment.

  In the case of the embodiment shown here, in the upper layer electrode shown in FIG. 3, the right side electrode E11 and the left side electrode E13 are plane-symmetric with respect to the YZ plane, and similarly, the right side electrode E21 and the left side electrode E23 are YZ It is plane-symmetric with respect to the plane. By adopting such a symmetrical structure, when the weight body 30 vibrates in the X-axis direction, the total amount of positive charges and the total amount of negative charges generated for these four upper electrodes is equal. To do. The merit of arranging a pair of electrodes, the right side electrode and the left side electrode, on both sides of the central electrode is that, as described above, with respect to vibration in the X-axis direction, the total amount of positive charges and the total amount of negative charges are equalized. It is in the point to be obtained.

  Finally, I will list another condition for efficient power generation based on externally applied vibration. That is to make the resonance frequency of the weight body 30 coincide with the vibration frequency given from the outside. Generally, in a vibration system, there is a resonance frequency that is uniquely determined according to its unique structure, and when the frequency of vibration given from the outside matches the resonance frequency, the vibrator vibrates most efficiently. And its amplitude is maximized. Therefore, when the frequency of vibration given from the outside is assumed in advance (for example, when it is determined in advance to be mounted on a specific vehicle and the frequency applied from the vehicle is known), In the structural design stage, it is preferable to design so that the resonance frequency matches the frequency.

<<< §2. Modified example of the first embodiment >>
Here, some modified examples of the two-axis power generation element according to the first embodiment described in §1 will be described.

<2-1 Modification of Number of Upper Layer Electrodes>
FIG. 6 is a plan view showing a modification of the power generating element shown in FIG. The only difference between them is the number of upper layer electrodes and their length. That is, in the case of the power generation element shown in FIG. 3, a total of six sets of upper layer electrodes E11 to E23 are formed as described above, whereas in the case of the power generation element shown in FIG. Only ~ E33 is formed. Since there is no difference with respect to other structures, a detailed structural description of the modification of FIG. 6 is omitted (of course, the power generation circuit rectifies three sets of upper layer electrodes E31 to E33 instead of the one shown in FIG. 5). It will be used to connect the elements and extract power).

  Here, in the case of the power generation element shown in FIG. 3, the upper layer electrode group includes weight body side electrode groups E11 to E13 disposed in the vicinity of the connection portion of the plate bridge portion 20 to the weight body 30, and the plate bridge portion. The fixed portion side electrode groups E21 to E23 arranged in the vicinity of the connecting portion with the 20 fixing portions 10, and the length in the longitudinal direction (Y-axis direction) is arranged in the vicinity of the connecting portion. It is set to the required length. On the other hand, the three sets of upper layer electrodes E31 to E33 in the modification shown in FIG. 6 are respectively opposed to the weight side electrode groups E11 to E13 and the fixed portion side electrode groups E21 to E23 in the example shown in FIG. Equivalent to connecting and fusing in the direction. For this reason, the upper layer electrodes E31 to E33 have the same length as the plate-like bridge portion 20.

  FIG. 7 is a table showing the polarities of charges generated in the upper layer electrodes E31 to E33 when displacement in the direction of each coordinate axis occurs in the weight body 30 of the power generating element shown in FIG. Considering that the table of FIG. 4 can be obtained for the power generation element shown in FIG. 3, it can be easily understood that the table of FIG. 7 is obtained for the power generation element shown in FIG. Therefore, for the power generation element shown in FIG. 6, if a power generation circuit according to the circuit shown in FIG. 5 is prepared, the charges generated in the upper electrodes E31 to E33 can be taken out as power.

  Actually, when the weight body 30 vibrates in the X-axis direction as shown in FIG. 2 (a) or vibrates in the Z-axis direction as shown in FIG. 2 (b), it occurs in the plate-like bridge portion 20. The stretching stress in the longitudinal direction (Y-axis direction) is the portion where the characters “extension” and “contraction” are described in FIG. 2, that is, the vicinity of the connection portion with the weight body 30 and the connection portion with the fixing portion 10. It will concentrate in the vicinity. The embodiment shown in FIG. 3 is an example in which the upper layer electrodes E11 to E23 are arranged only in these stress concentration portions, and is an example in which the most efficient electrode arrangement is performed. On the other hand, the embodiment shown in FIG. 6 is an example in which the upper layer electrode is arranged over the entire region including the portion where the stress is not concentrated, and the power generation amount per unit electrode area is not necessarily efficient. It becomes possible to reduce the number of electrodes.

  In any of the embodiments, the upper electrode is composed of three types of electrodes, that is, the center electrode, the right side electrode, and the left side electrode. As described in §1, the vibration energy in the Z-axis direction of the weight body 30 is Power generation based on vibration energy in the X-axis direction is possible, and with respect to vibration in the X-axis direction, the effect of keeping the total amount of positive charges and the total amount of negative charges as balanced as possible is obtained.

<2-2 Modification Example of Side Positioning of Upper Layer Electrode>
In both the embodiment shown in FIG. 3 and the embodiment shown in FIG. 5, the lower layer electrode E0 is formed on the upper surface of the plate-like bridge portion 20, the piezoelectric element 50 is formed on the upper surface of the lower layer electrode E0, and the center electrode Three types of upper layer electrodes, the right side electrode and the left side electrode, are formed on the upper surface of the plate-like bridge portion 20 via the lower layer electrode E0 and the piezoelectric element 50. Of the upper layer electrodes, the right side electrode and the left side electrode The side electrodes may be formed entirely or partially on the side surface of the plate-like bridge portion 20 via the lower layer electrode E0 and the piezoelectric element 50.

  FIG. 8 is a front sectional view showing a variation of the arrangement mode of the upper layer electrode in the power generation element according to the present invention. FIG. 8A is a front sectional view showing a cross section of the plate-like bridge portion 20 of the embodiment shown in FIG. 3 taken along the cutting line 8-8 in the figure. As illustrated, the lower layer electrode E0 and the piezoelectric element 50 are stacked on the upper surface of the plate-like bridge portion 20, and three types of upper layer electrodes E21, E22, and E23 are further disposed on the upper surface. Therefore, the polarization phenomenon of the piezoelectric element 50 occurs in the vertical direction of the figure. The arrangement of the upper layer electrode of the embodiment shown in FIG. 5 is the same.

  On the other hand, in the embodiment shown in FIG. 8 (b), the right side electrode and the left side electrode are arranged on the side surface. That is, in this embodiment, the lower layer electrode E0B is formed on the side surface as well as the upper surface of the plate-like bridge portion 20, and the piezoelectric element 50B is formed on the surface of the lower layer electrode E0B. That is, in the front sectional view, both the lower layer electrode E0B and the piezoelectric element 50B have a “U” shape, and are integrally formed from the upper surface of the plate-like bridge portion 20 to the left and right side surfaces. The arrangement of the three types of electrodes constituting the upper layer electrode group is the same as that the center electrode E22B is formed on the upper surface of the plate-like bridge portion 20 via the lower layer electrode E0B and the piezoelectric element 50B. The right side electrode E21B and the left side electrode E23B are formed on the side surface of the plate-like bridge portion 20 via the lower layer electrode E0B and the piezoelectric element 50B. FIG. 8B shows only the fixed part side electrode groups E21B to E23B, but the arrangement of the weight body side electrode groups E11B to E13B is the same.

  In this case, since each portion of the piezoelectric element 50B causes a polarization phenomenon in the thickness direction, the polarization phenomenon occurs in the vertical direction of the figure for the portion formed on the upper surface of the plate-like bridge portion 20, and the plate-like shape. A polarization phenomenon occurs in the left-right direction of the figure in the portion formed on the side surface of the bridge portion 20. Therefore, due to the stress generated in each part of the plate-like bridge part 20, charges having a predetermined polarity are generated in any of the six upper layer electrodes E11B to E13B and E21B to E23B. The expansion / contraction state of each part of the plate-like bridge portion 20 shown in FIG. 2 (a) does not change even on the side surface, so that it eventually occurs if a circuit similar to the power generation circuit 60 shown in FIG. 5 is prepared. It is possible to extract electric power based on electric charges.

  Compared with the embodiment shown in FIG. 8 (a), the embodiment shown in FIG. 8 (b) has a larger area of each upper electrode, and therefore the amount of charge generated in the upper electrode group also increases. Therefore, the latter has higher power generation efficiency than the former, but in the latter case, it is necessary to form a lower layer electrode, a piezoelectric element, and an upper layer electrode not only on the upper surface but also on the side surface of the plate-like bridge portion 20. Manufacturing costs will rise.

  On the other hand, in the embodiment shown in FIG. 8 (c), the right side electrode and the left side electrode are arranged so as to be continuous from the upper surface to the side surface. Also in this embodiment, as in the embodiment shown in FIG. 8B, the lower layer electrode E0C is formed on the side surface together with the upper surface of the plate-like bridge portion 20, and the piezoelectric element 50C is formed on the surface of the lower layer electrode E0C. Yes. Therefore, in the front sectional view, the lower layer electrode E0C and the piezoelectric element 50C have a “U” shape and are integrally formed from the upper surface of the plate-like bridge portion 20 to the left and right side surfaces.

  Here, the arrangement of the three types of electrodes constituting the upper layer electrode group is the same in that the center electrode E22C is formed on the upper surface of the plate-like bridge portion 20 via the lower layer electrode E0C and the piezoelectric element 50C. The right side electrode E21C and the left side electrode E23C are formed from the upper surface to the side surface of the plate-like bridge portion 20 via the lower layer electrode E0C and the piezoelectric element 50C. FIG. 8C shows only the fixed part side electrode groups E21C to E23C, but the arrangement of the weight body side electrode groups E11C to E13C is the same.

  As described above, each part of the piezoelectric element 50B causes a polarization phenomenon in the thickness direction thereof. Therefore, also in the embodiment shown in FIG. 8 (c), due to the stress generated in each part of the plate-like bridge part 20. , A charge having a predetermined polarity is generated in any of the six upper electrodes E11C to E13C and E21C to E23C. If a circuit similar to the power generation circuit 60 shown in FIG. Power extraction based on this is possible.

  Compared with the embodiment shown in FIG. 8 (b), in the embodiment shown in FIG. 8 (c), the area of the right side electrode and the left side electrode can be secured more widely. As a result, the power generation efficiency can be further increased. However, since it is necessary to form the right side electrode and the left side electrode from the upper surface to the side surface, the manufacturing cost is further increased.

  Of course, it is also possible to combine the arrangement form of the upper electrode in the embodiment shown in FIGS. 8 (a) to 8 (c) for each part. In FIG. 8 (d), the arrangement shown in FIG. 8 (b) is adopted for the right half, and the arrangement shown in FIG. 8 (c) is adopted for the left half. In this embodiment, the piezoelectric element is not formed as an integral structure, but is divided into two parts 51D and 52D.

  Specifically, in the embodiment shown in FIG. 8D, the lower layer electrode E0D is formed on the side surface as well as the upper surface of the plate-like bridge portion 20, and the piezoelectric elements 51D and 52D are formed on the surface. The piezoelectric element 51D is formed at a position covering the right side surface of the lower layer electrode E0D, and the piezoelectric element 52D is formed at a position covering the upper surface and the left side surface of the lower layer electrode E0D. The arrangement of the three types of electrodes constituting the upper layer electrode group is such that the central electrode E22D is formed on the upper surface of the plate-like bridge portion 20 via the lower layer electrode E0D and the piezoelectric element 52D, and the right side electrode E21D is The left side electrode E23D is formed from the upper surface to the side surface of the plate-like bridge portion 20 via the lower layer electrode E0D and the piezoelectric element 52D. Has been.

  As described above, the right side electrode and the left side electrode do not necessarily have to be symmetrical. However, in order to keep the total amount of positive charges and the total amount of negative charges generated with respect to vibration in the X-axis direction as balanced as possible. For this, it is preferable that the left and right are symmetrical as in the embodiment shown in FIGS. 8 (a) to 8 (c).

  In addition, the piezoelectric element does not necessarily have an integral structure, and as shown in FIG. 8 (d), independent elements may be arranged at positions corresponding to the upper layer electrodes. Above, the manufacturing process becomes easier with a single structure. Similarly, the lower layer electrodes may be arranged separately and independently at positions corresponding to the upper layer electrodes. However, practically, the manufacturing process is easier when the single layer structure is used.

  As described above, the embodiment shown in FIGS. 8B to 8D is described as a variation of the embodiment shown in FIG. 3 (the front sectional view corresponds to FIG. 8A). Of course, the embodiment shown in FIG. Similar variations are possible for the examples. Further, the second embodiment to be described later can be similarly modified with respect to the arrangement mode of the upper layer electrode.

<<< §3. Second embodiment (3-axis power generation type) >>
Subsequently, a second embodiment of the present invention will be described. The first embodiment described in §1 is a two-axis power generation type that generates power by converting vibration energy in the X-axis direction and vibration energy in the Z-axis direction that acted on the weight body 30 into electrical energy. The second embodiment described here is a three-axis power generation element that further has a function of converting vibration energy in the Y-axis direction into electric energy.

  Of course, in the case of the first embodiment as well, it is possible to convert vibration energy in the Y-axis direction into electric energy. However, as described above, the conversion efficiency is very low, and vibration in the X-axis or Z-axis direction. Compared to energy conversion efficiency, it is negligible. In the second embodiment described here, basically, two sets of plate-like bridge portions in the first embodiment are prepared, and these are combined in directions orthogonal to each other, so that the weight body is X-axis and Y-axis. The vibration energy can be efficiently converted into electric energy when the vibration is generated in any direction of the Z axis.

  FIG. 9 is a plan view (upper view (a)) and a side sectional view (lower view (b)) of the basic structure 100 constituting the power generating element according to the second embodiment of the present invention. As shown in FIG. 9 (a), this basic structure 100 includes a plate member 110 for a fixing portion, a first plate bridge portion 120, an intermediate connection portion 125, a second plate bridge portion 130, and a weight connection. This is a spiral structure having parts 140 and weight 150.

  Here, for convenience of explaining the vibration direction, the origin O is set at the center of gravity of the weight 150 in a state where the weight 150 is stationary, and an XYZ three-dimensional coordinate system is defined as shown. That is, in the plan view of FIG. 9 (a), the X axis is defined below the figure, the Y axis is defined on the right side of the figure, and the Z axis is defined vertically above the page. In the side sectional view of FIG. 9B, the Z-axis is defined above the figure, the Y-axis is defined on the right side of the figure, and the X-axis is defined vertically above the page. The side sectional view of FIG. 9B corresponds to a view of the basic structure 100 shown in the plan view of FIG. 9A taken along the YZ plane. Although not shown in FIG. 9 (a), the basic structure 100 is actually housed in the apparatus housing. FIG. 9B shows a bottom plate 200 that forms a part of the device casing, and shows a state in which the lower surface of the fixing plate member 110 is fixed to the upper surface of the bottom plate 200. .

  The plate member 110 for the fixing portion performs the same function as the fixing portion 10 in the first embodiment, and the root end portion (the left end in the figure) of the first plate-like bridge portion 120 is used as the bottom plate 200 of the apparatus housing. A component to be fixed. On the other hand, the root end portion of the second plate-like bridge portion 130 is connected to the distal end portion (right end in the drawing) of the first plate-like bridge portion 120 via the intermediate connection portion 125, so that the second plate-like shape is provided. A weight body 150 is connected to the distal end portion of the bridge portion 130 via a weight connection portion 140. As shown in FIG. 9 (a), the weight body 150 is a rectangular structure having a sufficient mass that functions as a vibrator, and the components 110, 120, 125, 130,. 140 is in a supported state.

  In FIG. 9 (b), the first plate-like bridge portion 120 and the intermediate connection portion 125 do not appear, but the first plate-like bridge portion 120, the intermediate connection portion 125, the second plate-like bridge portion 130, Both the weight connection part 140 and the weight body 150 have the same thickness (dimension in the Z-axis direction). On the other hand, the plate member 110 for fixing part has an excessive thickness part below. For this reason, as shown in FIG. 9 (b), in a state where the lower surface of the fixing member plate member 110 is fixed to the upper surface of the bottom plate 200, the first plate-like bridge portion 120, the intermediate connecting portion 125, the second The plate-like bridge portion 130, the weight connection portion 140, and the weight body 150 are all lifted from the upper surface of the bottom plate 200, and the weight body 150 is held in a suspended state.

  Here, at least the first plate-like bridge portion 120 and the second plate-like bridge portion 130 have flexibility, and therefore bend due to the action of external force. For this reason, when vibration is applied to the apparatus housing from the outside, a force is applied to the weight body 150 by this vibration energy, and the weight body 150 vibrates within the apparatus housing. For example, if the apparatus housing is attached to a vibration source such as a vehicle in such a direction that the XY plane is a horizontal plane and the Z axis is a vertical axis, the weight body is caused by vertical and horizontal vibrations applied from the vibration source. With respect to 150, vibration energy in the direction of each coordinate axis of XYZ is added.

  After all, in the basic structure 100 shown in FIG. 9, the first plate-like bridge portion 120 and the second plate-like bridge portion 130 each having flexibility are arranged in an L shape. The tip of the plate-like bridge portion 120 and the root end of the second plate-like bridge portion 130 are connected via an intermediate connecting portion 125, and a weight is provided beside the second plate-like bridge portion 130. The distal end portion of the second plate-like bridge portion 130 and the corner portion of the weight body 150 are connected via the weight connection portion 140 so that 150 is disposed. In addition, since the root end portion of the first plate-like bridge portion 120 is fixed to the upper surface of the bottom plate 200 of the apparatus housing by the fixing portion plate-like member 110 functioning as a fixing portion, the first plate-like bridge portion. The portion 120, the second plate-like bridge portion 130, and the weight body 150 are suspended in a suspended state above the bottom plate 200 of the apparatus housing in a state where no external force is applied.

  In particular, in the basic structure 100 shown in FIG. 9, the fixing portion is constituted by a fixing portion plate member 110 extending along the fixing portion longitudinal axis L <b> 0 parallel to the X axis, and this fixing portion plate member. A root end portion of the first plate-like bridge portion 120 is fixed to one end of the 110. Moreover, the first plate-like bridge portion 120 is disposed so as to extend in the Y-axis direction around the first longitudinal axis Ly parallel to the Y-axis, and the second plate-like bridge portion 130 is arranged along the X-axis. It arrange | positions so that it may extend in the X-axis direction centering | focusing on the parallel 2nd longitudinal direction axis | shaft Lx. For this reason, the structure constituted by the plate member 110 for the fixing portion, the first plate-like bridge portion 120, and the second plate-like bridge portion 130 has an “U” -shaped projection image on the XY plane. A U-shaped structure is formed, and a plate-like weight body 150 is arranged in an inner region surrounded by the U-shaped structure.

  Such a basic structure 100 has a structure suitable for mass production. That is, as can be seen from the plan view of FIG. 9 (a), the basic structure 100 is formed by forming a “U” -shaped void V in a rectangular plate member by etching or the like. It can be mass-produced by a process of creating a spiral structure as a whole.

  For example, in the embodiment shown here, a silicon substrate having a side of 5 mm square is prepared, and a groove having a width of about 0.3 mm is formed by etching, thereby forming a “U” -shaped void V, A "U" -shaped structure having a width of about 0.5 mm is used to fix the plate member 110 for the fixing portion, the first plate-like bridge portion 120, the intermediate connection portion 125, and the second plate-like bridge portion 130. The weight connection part 140 is formed. Regarding the thickness of each part, the thickness of the first plate-like bridge portion 120, the intermediate connection portion 125, the second plate-like bridge portion 130, the weight connection portion 140, and the weight body 150 is set to 0.5 mm. The thickness of the fixed portion plate member 110 was 1 mm.

  Of course, the dimension of each part can be set arbitrarily. In short, if the first plate-like bridge portion 120 and the second plate-like bridge portion 130 are set to dimensions having flexibility such that the weight body 150 can vibrate in the direction of each coordinate axis with a certain amplitude. The weight body 150 may be set to a size having a mass sufficient to generate vibration necessary for power generation by external vibration energy, and the plate member 110 for fixing portion is the entire basic structure 100. May be set to a dimension that can be firmly fixed to the bottom plate 200 of the apparatus housing.

  As described above, the structure of the basic structure 100 that is a component of the power generation element according to the second embodiment has been described with reference to FIG. 9. Constructed by adding elements.

  FIG. 10 (a) is a plan view of the power generating element according to the second embodiment (the device casing is not shown), and FIG. 10 (b) is a side cross-sectional view taken along the YZ plane. Yes (device housing is also shown). As shown in FIG. 10B, a layered lower layer electrode E00 is formed over the entire upper surface of the basic structure 100, and a layered piezoelectric element 300 is formed over the entire upper surface thereof. An upper electrode group consisting of a plurality of locally formed upper electrodes is formed on the upper surface of the piezoelectric element 300 (since FIG. 10B is a cross-sectional view in the YZ plane, Only the three upper layer electrodes Ex1, Ex2 and Ez1 arranged behind the cut surface appear in the drawing).

  The lower layer electrode and the upper layer electrode may be formed using a general conductive material such as a metal as in the first embodiment. In the example shown here, the lower layer electrode E00 and the upper layer electrode group are formed of a thin metal layer (a metal layer composed of two layers of a titanium film and a platinum film) having a thickness of about 300 nm. The piezoelectric element 300 is made of PZT (lead zirconate titanate), KNN (potassium sodium niobate) or the like in a thin film having a thickness of about 2 μm.

  As shown in FIG. 10 (b), in the case of this embodiment, an apparatus casing is constituted by the bottom plate 200 and the cover 400, and the basic structure 100 is accommodated in the apparatus casing. As described above, the basic structure 100 is fixed to the upper surface of the bottom plate 200 by the fixing plate member 110, and the weight body 150 is suspended in the apparatus housing. The cover 400 includes a top plate 410 and side plates 420, and the weight body 150 is displaced and vibrates in the internal space of the cover 400.

  If the distance between the upper surface of the weight body 150 and the lower surface of the top plate 410 and the distance between the lower surface of the weight body 150 and the upper surface of the bottom plate 200 are set to appropriate dimensions, the top plate 410 and the bottom plate 200 will be described. Can function as a stopper member. That is, since the inner wall surface of the apparatus housing functions as a control member that restricts excessive displacement of the weight body 150, excessive acceleration (acceleration that damages each of the plate-like bridge portions 120 and 130) occurs in the weight body 150. ), Excessive displacement of the weight body 150 can be restricted, and the situation where the plate-like bridge portions 120 and 130 are damaged can be avoided. However, if the gap dimension between the top plate 410 and the weight body 150 or the gap dimension between the bottom plate 200 and the weight body 150 is too narrow, it is affected by air damping, and power generation efficiency is reduced, so care must be taken.

  In the case of the embodiment shown here, the upper layer electrode group consists of 12 upper layer electrodes Ex1 to Ex4, Ey1 to Ey4, Ez1 to Ez4 (hatching in the figure clearly shows the electrode formation region as shown in FIG. 10 (a)). It is given for the sake of illustration and does not show a cross section). 10 (a) is a plan view of the power generating element as viewed from above, and thus the piezoelectric element 300 covering the entire surface of the basic structure can be seen. For convenience, FIG. 10 (a) The positions of the fixing plate member 110, the first plate bridge portion 120, the second plate bridge portion 130, the weight connection portion 140, and the weight body 150 are indicated by reference numerals in parentheses. .

  The role of the six upper layer electrodes arranged above the first plate-like bridge portion 120 is basically the six upper layer electrodes arranged above the plate-like bridge portion 20 shown in FIG. The role is the same. Similarly, the role of the six upper layer electrodes arranged above the second plate-like bridge portion 130 is basically the same as that of the six pieces arranged above the plate-like bridge portion 20 shown in FIG. This is the same as the role of the upper layer electrode.

  Here, four upper layer electrodes Ex1 to Ex4 (left and right side electrodes arranged on the second plate-like bridge portion 130 so as to extend along the second longitudinal axis Lx) including the symbol x, The four upper-layer electrodes Ey1 to Ey4 including the symbol y (the left and right side electrodes arranged on the first plate-like bridge portion 120 so as to extend along the first longitudinal axis Ly) are mainly heavy. Four upper layer electrodes Ez1 to Ez4 that are provided to take out the charge generated based on the vibration energy of the weight 150 in the horizontal direction (X-axis and Y-axis directions), and include z. (The central electrode disposed on the first longitudinal axis Ly of the first plate-like bridge portion 120 and the second longitudinal axis Lx of the second plate-like bridge portion 130) is mainly a weight body. Based on the vibration energy of 150 vertical directions (Z-axis direction) An electrode provided to serve retrieve the charge.

  Here, of the twelve upper layer electrodes shown in FIG. 10 (a), three electrodes formed at the tip of the first plate-like bridge 120 are respectively connected to the right on the first tip side. The side electrode Ey1, the first tip side central electrode Ez3, the first tip side left side electrode Ey2, and the three electrodes formed at the root end of the first plate-like bridge portion 120, The first root end side right side electrode Ey3, the first root end side central electrode Ez4, and the first root end side left side electrode Ey4, which are formed at the tip of the second plate-like bridge portion 130 These three electrodes are referred to as a second tip portion side right electrode Ex1, a second tip portion side center electrode Ez1, and a second tip portion side left side electrode Ex2, respectively. Three electrodes formed at the root end portion of 130 are respectively connected to the second root end side right side electrode Ex3, the second root end side central electrode Ez2, and the second It will be referred to as the root end side left side electrode Ex4.

  Here, the terms “right side” and “left side” mean the left and right when the upper surfaces of the plate-like bridge portions 120 and 130 are viewed from the root end side. The center electrodes Ez3, Ez4 are arranged on a first longitudinal axis Ly (a center axis parallel to the Y axis) that forms the center line of the first plate-like bridge portion 120, and the left and right side electrodes Ey1-Ey4. Are arranged symmetrically with respect to the first longitudinal axis Ly on the left and right sides thereof. Similarly, the center electrodes Ez1 and Ez2 are disposed on the second longitudinal axis Lx (center axis parallel to the X axis) that forms the center line of the second plate-like bridge portion 130, and the left and right side electrodes Ex1 to Ex4 are arranged so as to be symmetrical with respect to the second longitudinal axis Lx on both the left and right sides thereof.

  As shown in FIG. 10 (b), this power generation element further includes a power generation circuit 500. In FIG. 10B, the power generation circuit 500 is shown as a simple block, but a specific circuit diagram will be described later. As shown in the figure, wiring is provided between the power generation circuit 500 and the lower layer electrode E00 and the twelve upper layer electrodes Ex1 to Ex4, Ey1 to Ey4, Ez1 to Ez4, and the charges generated in each upper layer electrode are Then, it is taken out by the power generation circuit 500 through this wiring. Actually, each wiring can be formed by a conductive pattern formed on the upper surface of the piezoelectric element 300 together with each upper layer electrode. Further, when the basic structure is configured by a silicon substrate, the power generation circuit 500 can be formed on the silicon substrate (for example, the plate member 110 for the fixing portion).

  Eventually, the power generating element according to the second embodiment is a power generating element that generates power by converting vibration energy in the direction of each coordinate axis in the XYZ three-dimensional coordinate system into electric energy. A first plate-like bridge portion 120 that extends along the longitudinal axis Ly and has flexibility, is connected to the first plate-like bridge portion 120 (via the intermediate connection portion 125), and is parallel to the X-axis. A second plate-like bridge portion 130 that extends along the second longitudinal axis Lx and has flexibility, and is connected to the second plate-like bridge portion 130 (via the weight connection portion 140). The weight body 150, the first plate-shaped bridge portion 120, the second plate-shaped bridge portion 130, and the device housing 400 that houses the weight body 150, and one end of the first plate-shaped bridge portion 120 are connected to the device. A fixing part (fixing part plate member 110) that is fixed to the housing 400; A lower layer electrode E00 formed in layers on the surfaces of the bridge member 120 and the second plate bridge portion 130, a piezoelectric element 300 formed in layers on the surface of the lower layer electrode E00, and a surface of the piezoelectric element 300 The electric power generated by rectifying the current generated based on the charges generated in the upper electrode groups Ex1 to Ex4, Ey1 to Ey4, Ez1 to Ez4, and the upper and lower electrodes formed by a plurality of locally formed upper electrodes. And a power generation circuit 500 to be taken out.

  As described above, in the power generation element having such a structure, when an external force that vibrates the device casing 400 is applied, the weight body 150 vibrates in the device casing 400 due to the bending of the plate-like bridge portions 120 and 130. To do. Then, the bending of each of the plate-like bridge portions 120 and 130 is transmitted to the piezoelectric element 300, and the piezoelectric element 300 is similarly bent. Since the piezoelectric element 300 has a property of causing polarization in the thickness direction by the action of stress that expands and contracts in the layer direction, charges are generated on the upper surface and the lower surface, and the generated charges are generated by the upper layer electrodes Ex1 to Ex4, Ey1. To Ey4, Ez1 to Ez4 and the lower layer electrode E00.

  In the case of the embodiment shown here, as in the embodiment described in §1, when a stress extending in the layer direction is applied, a positive charge is generated on the upper surface side, a negative charge is generated on the lower surface side, and conversely, a stress contracting in the layer direction Is used, the piezoelectric element 300 that generates a negative charge on the upper surface side and a positive charge on the lower surface side is used. Of course, in the case of the second embodiment, a piezoelectric element having any polarization characteristic may be used.

  Next, let's look at the specific power generation operation of this power generation element. FIG. 11 is a plan view showing a stretched state of each upper layer electrode formation position when the weight body 150 of the basic structure 100 shown in FIG. 9 generates a displacement Δx (+) in the X-axis positive direction. Similarly, FIG. 12 is a plan view showing a stretched state when a displacement Δy (+) in the Y-axis positive direction is generated, and FIG. 13 is a stretched state when a displacement Δz (+) in the Z-axis positive direction is generated. FIG. Such a displacement occurs when acceleration in the positive direction of each coordinate axis acts on the weight body 150, and due to the displacement, each of the plate-like bridge portions 120, 130 bends, and the basic structure The body 100 deforms. However, in FIG. 11 to FIG. 13, for convenience of illustration, depiction of the displacement state of the basic structure 100 is omitted, and the expansion / contraction state of each upper layer electrode formation position is indicated by arrows (the arrows with arrows at both ends extend) A pair of arrows facing each other indicates a contracted state).

  When the weight 150 is displaced in the positive direction of the X axis Δx (+), as shown in FIG. 11, the second tip side right side electrode Ex1, which is disposed outside the spiral basic structure 100, is provided. A stress extending in the longitudinal direction acts on the second root end side right side electrode Ex3 and the first tip side right side electrode Ey1, but the first root end side right side electrode Ey3 The stress which shrinks in the longitudinal direction acts. On the other hand, the second tip side left side electrode Ex2, the second root end side left side electrode Ex4, and the first tip side left side electrode Ey2 disposed inside the spiral basic structure 100 are provided. In both cases, stress contracting in the longitudinal direction acts, but stress extending in the longitudinal direction acts on the first root end side left side electrode Ey4.

  Although the first root end side right side electrode Ey3 is an electrode located outside the spiral basic structure 100, the right side electrodes Ex1, Ex3, Ey1 located outside the other side are expanded and contracted. Although the state is reversed, the first root end side right side electrode Ey4 is an electrode located inside the spiral basic structure 100, but the left side electrodes Ex2, Ex4 located inside other spiral side basic structures 100 , Ey2 is reversed in the stretched state. In order to explain the reason why the expansion and contraction reversal occurs at the root end of the first plate-like bridge portion 120, a complicated theoretical development is required. It has been confirmed that the stretching stress as shown in the figure is generated by executing a structural mechanics simulation using the above (see FIG. 19 described later).

  In addition, about four center electrodes Ez1-Ez4 arrange | positioned on a centerline, since a slightly reverse stress will act on a right half and a left half, as a whole, a stress balances and expansion-contraction arises. It can be considered that there is nothing.

  FIG. 11 shows a state when a displacement Δx (+) in the X-axis positive direction occurs. When a displacement Δx (−) in the X-axis negative direction occurs, the weight body 150 is displaced in the opposite direction. Therefore, the stretched state of each part is the reverse of the state shown in FIG. Therefore, when vibration energy having a vibration component in the X-axis direction is applied to the device housing 400, the stretched state and the inverted state shown in FIG. It will be.

  On the other hand, when the weight body 150 is displaced in the Y-axis positive direction Δy (+), as shown in FIG. 12, the second root end side right side located on the outside of the spiral basic structure 100 is used. The electrode Ex3, the first tip side right side electrode Ey1, and the first root end side right side electrode Ey3 are all subjected to stress contracting in the longitudinal direction, but the second tip side right side electrode Ex1. The stress that extends in the longitudinal direction acts on. On the other hand, the second root end side left side electrode Ex4, the first tip end side left side electrode Ey2, and the first root end side left side electrode Ey4 disposed inside the spiral basic structure 100 are arranged. In both cases, a stress that extends in the longitudinal direction acts, but a stress that contracts in the longitudinal direction acts on the second tip side left electrode Ex2.

  The second tip side right side electrode Ex1 is an electrode located outside the spiral basic structure 100, but is in a stretched state with the other right side electrodes Ex3, Ey1, Ey3 located outside. The second tip side left electrode Ex2 is an electrode located inside the spiral basic structure 100, but the left side electrodes Ex4, Ey2, Ey4 located inside the other side The telescopic state is reversed. In order to explain the reason why the expansion and contraction reversal occurs at the tip of the second plate-like bridge portion 130, a complicated theoretical development is necessary, so that the explanation is omitted here. It is confirmed that the stretching stress as shown in the figure is generated by executing the structural mechanical simulation (see FIG. 20 described later).

  Also in this case, the four central electrodes Ez1 to Ez4 arranged on the center line are subjected to slight reverse stresses in the right half and the left half, so that the stress is balanced and stretched as a whole. It can be considered that does not occur.

  FIG. 12 shows a state when a displacement Δy (+) in the Y-axis positive direction occurs. When a displacement Δy (−) in the Y-axis negative direction occurs, the weight body 150 is displaced in the opposite direction. Therefore, the stretched state of each part is the reverse of the state shown in FIG. Therefore, when vibration energy having a vibration component in the Y-axis direction is applied to the device housing 400, the stretched state and the inverted state shown in FIG. It will be.

  Finally, when the weight body 150 is displaced in the positive direction of the Z-axis Δz (+), as shown in FIG. 13, the three electrodes Ey1, Ey2 on the distal end side of the first plate-like bridge portion 120 are used. , Ez3 and three electrodes Ex1, Ex2 and Ez1 on the distal end side of the second plate-like bridge portion 130 are subjected to stress extending in the longitudinal direction, but the root end portion of the first plate-like bridge portion 120 Stress contracting in the longitudinal direction acts on the three electrodes Ey3, Ey4, Ez4 on the side and the three electrodes Ex3, Ex4, Ez2 on the root end side of the second plate-like bridge portion 130. Although the detailed explanation about the reason why such stress acts is omitted, the present inventor confirmed that the stretching stress as shown in the figure is generated by executing a structural mechanical simulation using a computer. (See FIG. 21 described later).

  FIG. 13 shows a state when a displacement Δz (+) in the positive direction of the Z-axis is generated. When the displacement Δz (−) in the negative direction of the Z-axis is generated, the weight body 150 is displaced in the reverse direction. Therefore, the stretched state of each part is the reverse of the state shown in FIG. Therefore, when vibration energy having a vibration component in the Z-axis direction is applied to the apparatus housing 400, the stretched state and the inverted state shown in FIG. It will be.

  FIG. 14 shows the power generation element shown in FIG. 10 with the lower layer electrode E00 as a reference potential and when the weight 150 is displaced in the respective coordinate axis directions, the upper layer electrodes Ex1 to Ex4, Ey1 to Ey4, and Ez1 to Ez1. It is a table | surface which shows the polarity of the electric charge which arises in Ez4. The sign “+” in the table indicates the generation of positive charge, and the sign “−” indicates the generation of negative charge. Further, the symbol “0” indicates that no charge is generated or that a small amount of charge is generated as compared with the case indicated by the symbols “+” and “−”. Practically, the generated charge in the column corresponding to the code “0” is not a significant amount, and will be ignored in the following description.

  As described above, when displacement in the direction of each coordinate axis occurs in the weight body 150, expansion and contraction stress as shown in FIGS. 11 to 13 is applied to each portion of each plate-like bridge portion 120 and 130. On the other hand, in the piezoelectric element 300, when a stress extending in the layer direction is applied, a positive charge is generated on the upper surface side, a negative charge is generated on the lower surface side, and when a stress contracting in the layer direction is applied, a negative charge is generated on the upper surface side. Has polarization characteristics that cause Based on these points, it can be easily understood that the table shown in FIG. 14 is obtained.

  For example, the result of each column of “displacement Δx (+)” in the first row in FIG. 14 is “+” in the upper electrode column of the expanding portion and the upper electrode column of the contracting portion in the stretch distribution shown in FIG. "-", "0" is written in the upper electrode column where no expansion or contraction occurs as a whole. Similarly, the result of each column of “displacement Δy (+)” in the second row corresponds to the expansion / contraction distribution shown in FIG. 12, and the result of “displacement Δz (+)” in the third row. The results in each column correspond to the stretch distribution shown in FIG.

  The table of FIG. 14 shows the charge generated in each upper layer electrode when displacement Δx (+), Δy (+), Δz (+) in the positive direction of each coordinate axis occurs with respect to the weight 150. However, when displacements Δx (−), Δy (−), and Δz (−) in the negative direction of each coordinate axis occur, a result obtained by reversing the sign of the table in FIG. 14 is obtained. Normally, when vibration energy is applied from the outside, the weight body 150 vibrates in the apparatus housing 400, and therefore, the sign of the table shown in FIG. 14 is inverted in synchronization with the period of the vibration. In addition, the amount of generated charge is periodically increased or decreased.

  Actually, since the vibration energy given from the outside has a component in each coordinate axis direction in the XYZ three-dimensional coordinate system, the displacement of the weight body 150 is Δx (±), Δy (±), Δz (± ), And will change from moment to moment. For this reason, for example, when the displacements Δx (+) and Δy (+) occur at the same time or the displacements Δx (+) and Δz (+) occur at the same time, as shown in the table of FIG. In Ey2, both a positive charge and a negative charge are generated, and some of the charges are canceled out and cannot be effectively extracted.

  As described above, depending on the vibration mode of the weight body 150, 100% efficient power generation is not necessarily performed. However, as a whole, the vibration energy of the weight body 150 in the X-axis direction, Electric power can be generated by taking out energy in the three-axis directions, ie, vibration energy and vibration energy in the Z-axis direction. As described above, the power generation using the vibration energy of all three axes of the weight body 150 is a characteristic of the power generation element according to the second embodiment of the present invention. The objective of converting vibration energy containing a directional component into electrical energy as much as possible and obtaining high power generation efficiency is achieved.

  The power generation circuit 500 plays a role of taking out electric power by rectifying a current generated based on charges generated in the upper layer electrodes Ex1 to Ez4 and the lower layer electrode E00. In the case of the embodiment shown here, the lower layer electrode E00 serves to ensure the reference potential as a common electrode, so in reality, the current flowing out from each of the upper layer electrodes Ex1 to Ez4 and the current flowing into each of the upper layer electrodes Ex1 to Ez4. May be collected separately to store electricity.

  FIG. 15 is a circuit diagram showing a specific configuration of the power generation circuit 500 used in the power generation element shown in FIG. The basic circuit configuration is the same as that of the power generation circuit 60 shown in FIG. That is, Px1 to Px4, Py1 to Py4, and Pz1 to Pz4 indicate a part of the piezoelectric element 300, and correspond to portions that are located immediately below the upper layer electrodes Ex1 to Ex4, Ey1 to Ey4, and Ez1 to Ez4, respectively. Further, E00 indicated by a white circle on the circuit diagram corresponds to the lower layer electrode, Ex1 to Ex4, Ey1 to Ey4, and Ez1 to Ez4 correspond to the upper layer electrode.

  Dx1 (+) to Dz34 (−) are rectifier elements (diodes), and each rectifier element with a symbol (+) plays a role of taking out a positive charge generated in each upper layer electrode. Each of the rectifying elements marked with serves to take out a negative charge generated in each upper layer electrode.

  The upper layer electrodes Ex1 to Ex4 and Ey1 to Ey4 are connected to a pair of independent positive and negative rectifier elements Dx1 (+), Dx1 (−), etc., whereas the upper layer electrodes Ez1 and Ez3 have A pair of positive and negative rectifier elements Dz13 (+) and Dz13 (-) common to both are connected, and a pair of positive and negative rectifier elements Dz24 (+) and Dz24 (-) common to both are connected to the upper layer electrodes Ez2 and Ez4. Has been. As can be seen from the table of FIG. 14, the upper layer electrodes Ez1 and Ez3 always generate charges of the same polarity, and the upper layer electrodes Ez2 and Ez4 always generate charges of the same polarity. This is because a common rectifying element can be used.

  On the other hand, Cf is a smoothing capacitive element (capacitor). The positive charge taken out is supplied to the positive terminal (upper terminal in the figure) and the negative charge taken out to the negative terminal (lower terminal in the figure). Is supplied. Similar to the power generation circuit 60 shown in FIG. 5, the capacitive element Cf plays a role of smoothing the pulsating flow based on the generated charge, and the impedance of the capacitive element Cf is almost ignored at the steady time when the vibration of the weight body 150 is stable. Yes. In the power generation circuit 60 shown in FIG. 5, the rectifying elements D0 (+) and D0 (−) are used to take out the charges generated in the lower layer electrode E0. However, in the power generation circuit 500 shown in FIG. A configuration is adopted in which both terminals of the element Cf are connected to the lower layer electrode E00 via the resistance elements Rd1 and Rd2. Even with such a configuration, it is possible to extract charges generated in the upper and lower electrode layers.

  Again, ZL connected in parallel to the capacitive element Cf indicates the load of the device that receives the supply of power generated by the power generation element. The resistance values of the resistance elements Rd1, Rd2 are set so as to be sufficiently larger than the impedance of the load ZL. Similar to the power generation circuit 60 shown in FIG. 5, in order to improve power generation efficiency, it is preferable to match the impedance of the load ZL and the internal impedance of the piezoelectric element 300. Therefore, when a device to be supplied with power is assumed in advance, it is preferable to design the power generating device by adopting a piezoelectric element having an internal impedance matched with the impedance of the load ZL of the device.

  Eventually, the power generation circuit 500 is directed from the upper layer electrodes Ex1 to Ez4 toward the positive electrode side of the capacitive element Cf in order to guide the positive charges generated in the capacitive element Cf and the upper layer electrodes Ex1 to Ez4 to the positive electrode side of the capacitive element Cf. Rectifier elements Dx1 (+) to Dz34 (+) for positive charges with the forward direction being in the forward direction and from the negative electrode side of the capacitive element Cf to guide negative charges generated in the upper layer electrodes Ex1 to Ez4 to the negative electrode side of the capacitive element Cf. Negative charge rectifying elements Dx1 (−) to Dz34 (−) whose forward direction is toward each of the upper layer electrodes Ex1 to Ez4, and the electric energy converted from vibration energy is smoothed by the capacitive element Cf. The function of supplying to the load ZL is fulfilled.

  Also in the circuit shown in FIG. 15, the load ZL includes positive charges extracted by the positive charge rectifying elements Dx1 (+) to Dz24 (+) and negative charge rectifying elements Dx1 (−) to Dz24 ( The negative charge taken out in (−) is supplied. Therefore, in principle, the most efficient power generation is possible if the total amount of positive charges and the total amount of negative charges generated at the upper layer electrodes Ex1 to Ez4 are equal at each moment.

  As described above, of the upper layer electrodes shown in FIG. 10, the left and right side electrodes are arranged so as to be symmetric with respect to the longitudinal axis Lx or Ly as the central axis. If such a symmetrical structure is adopted, when the weight body 150 vibrates in the X-axis direction, as shown in FIG. 11, the total amount of positive charges generated in a pair of left and right side electrodes arranged at the same location The total amount of negative charges is almost equal. Similarly, when the weight body 150 vibrates in the Y-axis direction, as shown in FIG. 12, the total amount of positive charges and the total amount of negative charges generated in the pair of left and right side electrodes arranged at the same location are almost equal. Will be equal. As described above, the merit of arranging the pair of electrodes, the right side electrode and the left side electrode, on both sides of the central electrode is that the total amount of positive charges and the total amount of negative charges with respect to the vibration in the X-axis direction and the vibration in the Y-axis direction. It is in the point that the effect of equalizing is obtained.

  Of course, also in the second embodiment, the most efficient power generation is possible when the resonance frequency of the weight body 150 determined based on the unique structure of the basic structure 100 matches the vibration frequency given from the outside. become. Therefore, when the frequency of vibration given from the outside is assumed in advance, it is preferable to design the basic structure 100 so that the resonance frequency matches the frequency at the structural design stage.

<<< §4. Power generation device using second embodiment >>>
Here, an embodiment that enables more efficient power generation by preparing a plurality of sets of power generation elements (elements shown in FIG. 10) according to the second embodiment described in §3 will be described. In the present application, for the sake of distinction as terms, the set of devices shown in the first embodiment described in §1, the modified example described in §2, and the second embodiment described in §3 is referred to as “power generation A device having a function of supplying a plurality of sets of “power generation elements” and supplying the electric power extracted by each power generation element to the outside will be referred to as “power generation device”.

  FIG. 16 is a plan view showing the structure of the basic structure 1000 of the power generation apparatus using the four power generation elements shown in FIG. 10 (in order to clearly show the planar shape, hatching is given to the inside of the structure. ). This basic structure 1000 is a fusion of four sets of basic structures 100A, 100B, 100C, and 100D. Each of the individual basic structures 100A, 100B, 100C, and 100D has the same structure as the basic structure 100 shown in FIG. 9, and each includes a plate member 110 for a fixing portion, a first plate-like bridge portion 120, and a first bridge member 120. 2 plate bridge portions 130 and weights 150.

  In FIG. 16, each part of the basic structures 100 </ b> A, 100 </ b> B, 100 </ b> C, and 100 </ b> D is also shown with A to D at the end of the reference numerals. For example, the basic structure 100A includes the fixed plate member 110A, the first plate bridge portion 120A, the second plate bridge portion 130A, and the weight body 150A. However, the basic structures adjacent to each other in the upper and lower directions in the figure have a structure in which a pair of fixing plate members 110 are fused. Therefore, the fixing member plate member 110A of the basic structure 100A and the fixing member plate member 110B of the basic structure 100B are actually merged to form one fixing member plate member 110AB. Similarly, the fixing member plate member 110C of the basic structure 100C and the fixing member plate member 110D of the basic structure 100D are actually fused to form one fixing member plate member 110CD. doing.

  Of course, an actual power generation apparatus is realized by adding a lower layer electrode, a piezoelectric element, an upper layer electrode, and a power generation circuit to the basic structure 1000 shown in FIG. Specifically, for example, a common lower layer electrode is formed on the entire upper surface of the basic structure 1000, a common piezoelectric element is formed on the entire upper surface, and a plurality of individual electrodes are locally localized at predetermined locations on the upper surface. An upper layer electrode may be formed (of course, the lower layer electrode and the piezoelectric element may be configured independently for each part).

  Here, the power generation circuit may be a circuit in which four sets of power generation elements are integrated so that the generated charges taken out from the four sets of power generation elements can be output collectively. Specifically, in the power generation circuit 500 shown in FIG. 15, the rectifying element is connected to the upper electrode of each power generation element, but the capacitance element Cf is common to the four power generation elements. The power energy obtained from all the power generation elements can be stored here. Further, the lower layer electrodes E00 of the four sets of power generating elements are connected to each other so as to have the same potential. Of course, the resistance elements Rd1 and Rd2 may be the same for the four power generation elements.

  One set of power generation elements shown in FIG. 10 generates power based on the electric charge collected from 12 upper layer electrodes, and a power generation device configured by using four sets of them generates a total of 48 upper layer electrodes. Power generation can be performed based on the charge collected from the battery.

  When a power generation device is configured by combining a plurality of power generation elements, the X-axis direction and / or the Y-axis direction of some power generation elements are different from these directions of another power generation element. It is preferable to arrange them in the direction. By adopting such an arrangement, the effect of making the total amount of positive charges and the total amount of negative charges generated in each upper layer electrode as equal as possible is obtained at each moment, and more efficient power generation becomes possible.

  For example, in the case of the basic structure 1000 shown in FIG. 16, the coordinate axes (the X axis and the Y axis defined as the basic structure 100 shown in FIG. 9) for each of the basic structures 100A to 100D are drawn in the figure. However, it can be seen that the combinations of orientations are different.

  That is, the basic structure 100A corresponds to a structure obtained by rotating the basic structure 100 shown in FIG. 9 by 90 ° counterclockwise. With reference to the basic structure 100A, the basic structure 100B is It is a mirror image of the direction. Further, based on the basic structures 100A and 100B shown in the left half of the figure, the basic structures 100C and 100D shown in the right half of the figure are mirror images in the horizontal direction of the figure. .

  After all, the power generation device configured using the basic structure 1000 shown in FIG. 16 has four power generation elements, and the first power generation element (element using the basic structure 100A) in the X-axis direction and Y When the axial direction is used as a reference, the second power generation element (element using the basic structure 100B) is arranged in the direction in which the Y-axis direction is reversed, and the third power generation element (element using the basic structure 100D) is arranged. ) Is arranged in the direction in which the X-axis direction is reversed, and the fourth power generation element (element using the basic structure 100C) is arranged in the direction in which both the X-axis direction and the Y-axis direction are reversed. . As a result, the Z-axis direction of the first power generation element and the fourth power generation element is a direction vertically upward on the page, whereas the Z-axis direction of the second power generation element and the third power generation element is In the direction perpendicular to the paper surface.

  In this way, if the power generation device is configured by adopting a complementary arrangement for the four power generation elements, acceleration acts in a specific direction, and the weight body of each power generation element is displaced in the specific direction. Even in this case, since the directions of the coordinate systems defined for the individual power generation elements are different, the displacement directions for the respective coordinate systems are complementary. For this reason, when a positive charge is generated in a specific upper layer electrode of one power generation element, a negative charge is generated in a corresponding upper layer electrode of another power generation element. Therefore, when viewed as the entire four sets of power generating elements, an effect of equalizing the total amount of positive charges generated and the total amount of negative charges can be obtained.

  By the way, as described above, in order to perform efficient power generation based on externally applied vibration, it is preferable to make the resonance frequency of the weight body 150 coincide with the externally applied vibration frequency. Therefore, for example, when the power generating element according to the present invention is mounted in a specific vehicle and used in advance, and the frequency f applied from the vehicle is known, the structural design of the basic structure 100 is determined. At the stage of performing, it is preferable to design so that the resonance frequency of the weight body 150 matches the frequency f applied from the vehicle.

  However, in the case where the power generating element according to the present invention is provided as a general general-purpose product, it is impossible to design such a dedicated product. Therefore, the most common vibration frequency f is determined and the resonance frequency is determined. Must be designed to match the frequency f. In an actual usage environment, efficient power generation is possible if vibration having a frequency close to the resonance frequency f is applied, but the power generation efficiency decreases as the frequency of the external vibration increases away from the resonance frequency f. I cannot deny it.

  Therefore, in order to enable power generation corresponding to a wide range of vibration frequencies, as described above, a plurality of power generation elements are combined to form a power generation apparatus, and the weight bodies of the plurality of power generation elements are It is possible to adopt an approach that has different resonance frequencies.

  One specific method of changing the resonance frequency for each power generating element is to change the mass of each weight body. FIG. 17 is a plan view showing the structure of the basic structure of the power generation apparatus according to the modification of the power generation apparatus shown in FIG. 16 (in order to clearly show the planar shape, the portion inside the structure is hatched). . In this modified example, variations are given to the masses of the respective weight bodies of the four sets of power generating elements by changing the planar area thereof.

  A basic structure 2000 shown in FIG. 17 is obtained by fusing four sets of basic structures 100E, 100F, 100G, and 100H. Each of the individual basic structures 100E, 100F, 100G, and 100H basically has the same structure as that of the basic structure 100 shown in FIG. 9, and therefore, each part thereof is also denoted by reference numerals 110, 120, and 130, respectively. , 150 are appended with E to H (similar to the example shown in FIG. 16, the fixed plate members 110EF and 110GH are shared).

  In the case of the basic structure 1000 shown in FIG. 16, the weights 150A, 150B, 150C, and 150D of the four sets of basic structures have the same size (mass), but the basic structure 2000 shown in FIG. In this case, the sizes (mass) of the weight bodies 150E, 150F, 150G, and 150H of the four sets of basic structures are reduced in the order of 150E> 150F> 150G> 150H. Specifically, each of the weights 150E, 150F, 150G, and 150H is a plate-like member having the same thickness, but as shown in FIG. 17, the areas of the projected images on the XY plane are different from each other. The mass of each is different.

  Of course, each mass may be changed by changing the thickness (dimension in the Z-axis direction) of each weight body. In short, by setting the areas of the projected images of the weight bodies on the XY plane to be different from each other, setting the thicknesses in the Z-axis direction to be different from each other, or setting both of them, a plurality of settings can be made. What is necessary is just to make it the mass of the weight body of an electric power generation element differ.

  The resonance frequency of the weight body varies depending on its mass. Therefore, if the masses of the weights 150E, 150F, 150G, and 150H are mE, mF, mG, and mH (mE> mF> mG> mH in the example of FIG. 17), the resonance frequencies fE, fF , FG, and fH are different from each other.

  Another method of changing the resonance frequency of the weight body for each power generating element is to change the structure of each plate-like bridge portion. Specifically, the first plate-like bridge portion and / or the second plate-like bridge portion of the plurality of power generating elements are set so that the areas of the projected images on the XY plane are different from each other, or in the Z-axis direction For example, the thicknesses may be set to be different from each other, or both may be set. Even if such setting is performed, the resonance frequencies fE, fF, fG, and fH of the weight bodies 150E, 150F, 150G, and 150H can be made different.

  As described above, when the resonance frequencies of the respective weight bodies of the four sets of power generation elements are made different from each other, it is possible to generate power corresponding to a wide range of vibration frequencies. For example, in the case of the above example, four resonance frequencies fE, fF, fG, and fH are set. Therefore, if the frequency of the vibration given from the outside is close to any of these, the proximity frequency is Efficient power generation can be expected for a power generation element having a resonance frequency.

  Of course, if the frequency f applied from the vehicle is known to be mounted and used in a specific vehicle, the resonance frequency of each weight body of the four sets of power generating elements is set to f. Most preferably, it is set. However, in the case of a power generation device provided as a general general-purpose product, it cannot be specified in which vibration environment it is used. In that case, an expected range of the vibration frequency that is considered to be the most general is set, and the basic structure of each power generating element is set so that four resonance frequencies fE, fF, fG, and fH are distributed within the expected range. Just design.

<<< §5. Modified example of the second embodiment >>
Here, some modifications of the three-axis power generation element according to the second embodiment described in §3 will be described.

<5-1 Modification of Number of Upper Layer Electrodes>
§2-1 shows a modification in which three upper layer electrodes E31 to E33 as shown in FIG. 6 are used in place of the six upper layer electrodes E11 to E23 in the two-axis power generation element shown in FIG. It was. Thus, the modification which changes the number of upper layer electrodes is possible also about the triaxial power generation type power generation element shown in FIG.

  Specifically, in FIG. 10A, of the six upper layer electrodes formed on the first plate-like bridge portion 120, a pair of central electrodes arranged on the first longitudinal axis Ly. Ez3 and Ez4 are fused to one elongated central electrode, and a pair of right side electrodes Ey1 and Ey3 arranged on the right side thereof are fused to one elongated right side electrode, and a pair arranged on the left side. The left side electrodes Ey2 and Ey4 may be fused to one elongated left side electrode. Then, the first plate-like bridge portion 120 has three elongated shapes extending in the direction parallel to the Y-axis, like the upper layer electrode formed on the plate-like bridge portion 20 of the modification shown in FIG. An upper layer electrode will be arranged. Similarly, in FIG. 10A, the six upper layer electrodes formed on the second plate-like bridge portion 130 can be replaced with three elongated upper layer electrodes extending in the direction parallel to the X axis. it can.

  After all, in such a modification, the number of upper layer electrodes is reduced to six, but the configuration of the basic structure 100 is not changed. That is, also in the basic structure 100 in this modified example, the root end portion of the first plate-like bridge portion 120 is fixed to the bottom plate 200 of the apparatus housing by the fixing portion plate member 110 that functions as a fixing portion. The front end portion of the first plate-like bridge portion 120 is connected to the root end portion of the second plate-like bridge portion 130, and the weight body 150 is connected to the front end portion of the second plate-like bridge portion 130. When an external force that vibrates the device casing is applied, the weight 150 vibrates in each coordinate axis direction within the device casing due to the bending of the first plate-like bridge portion 120 and the second plate-like bridge portion 130. This is exactly the same as the power generation element shown in FIG.

  Moreover, the piezoelectric element 300 has a property of causing polarization in the thickness direction by the action of stress that expands and contracts in the layer direction, and the structure of the upper layer electrode group is the lower electrode on the surface of the first plate-like bridge portion 120. A first upper electrode group formed via E00 and the piezoelectric element 300, and a second upper electrode group formed via the lower layer electrode E00 and the piezoelectric element 300 on the surface of the second plate-like bridge portion 130; Are exactly the same as the power generating element shown in FIG.

  Here, the first upper-layer electrode group formed on the first plate-like bridge portion 120 includes a first central electrode (a fusion of the electrodes Ez3 and Ez4 shown in FIG. 10A), the first Three types: right side electrode (fused with electrodes Ey1 and Ey3 shown in FIG. 10 (a)) and first left side electrode (fused with electrodes Ey2 and Ey4 shown in FIG. 10 (a)) Each of the upper layer electrodes is disposed so as to extend along the first longitudinal axis Ly, and is opposed to a predetermined region of the lower layer electrode E00 with the piezoelectric element 300 interposed therebetween. The center electrode of the first plate-like bridge portion 120 is arranged at the position of the center line along the first longitudinal axis Ly on the upper surface side of the first plate-like bridge portion 120, and the first right side electrode is the first center electrode It is arranged on one side of the electrode, and the first left side electrode is arranged on the other side of the first central electrode It becomes door.

  The second upper electrode group formed on the second plate-like bridge portion 130 includes a second central electrode (a fusion of the electrodes Ez1 and Ez2 shown in FIG. 10 (a)), the second right electrode There are three types of electrodes: the side electrode (fused with the electrodes Ex1 and Ex3 shown in FIG. 10 (a)) and the second left side electrode (fused with the electrodes Ex2 and Ex4 shown in FIG. 10 (a)). Each of the upper layer electrodes is disposed so as to extend along the second longitudinal axis Lx, and is opposed to a predetermined region of the lower layer electrode E00 with the piezoelectric element 300 interposed therebetween. The center electrode is disposed at the position of the center line along the second longitudinal axis Lx on the upper surface side of the second plate-like bridge portion 130, and the second right side electrode is the second center electrode. The second left side electrode is disposed on the other side of the second central electrode. To become.

  Thus, even in a modification in which the 12 upper electrodes in the triaxial power generation element shown in FIG. 10 are fused and replaced with 6 upper electrodes, the upper electrode includes the center electrode, the right side electrode, Since the left side electrode is composed of three types of electrodes, the effect of keeping the total amount of positive charges and the total amount of negative charges as balanced as possible with respect to vibration in the X-axis direction or the Y-axis direction can be obtained.

  However, in practice, it is more preferable to adopt the embodiment using 12 upper electrodes as shown in FIG. 10 than adopting the above-described modification using the 6 upper electrodes. This is because the former provides higher power generation efficiency than the latter. The reason will be described below.

  In the embodiment using twelve upper layer electrodes shown in FIG. 10, two sets of plate-like bridge portions 120 and 130 arranged in an L shape so as to be orthogonal to each other are used. If these plate-like bridge parts 120 and 130 are regarded as a single body, they have the same configuration as the plate-like bridge part 20 shown in FIG. 3, and have six upper-layer electrodes arranged on the upper surface side. However, the behavior of the stretching stress generated in each part when the weight body is displaced is slightly different.

  That is, in the case of the plate-like bridge portion 20 shown in FIG. 3, when the weight body 30 is displaced in the positive direction of the X axis, as shown in FIG. 2 (a), the left side of the plate-like bridge portion 20 (the upper side of the figure). ) Extends on both the fixed portion 10 side and the weight body 30 side, and the right side (the lower side in the drawing) of the plate-like bridge portion 20 is contracted on both the fixed portion 10 side and the weight body 30 side. As described above, since the expansion and contraction state of the same side surface of the plate-like bridge portion 20 is the same between the fixed portion 10 side and the weight body 30 side, the pair of right side electrodes E11 and E21 shown in FIG. Even if they are fused and replaced with the right side electrode E31 shown in FIG. 6, the pair of left side electrodes E13 and E23 shown in FIG. 3A are fused and replaced with the left side electrode E33 shown in FIG. Since the polarity of the generated charges of the pair of electrodes is the same, the charges are canceled and do not disappear.

  However, in the case of the two pairs of plate-like bridge portions 120 and 130 shown in FIG. 10, when the weight body 150 is displaced in the positive direction of the X-axis, as shown in FIG. The first tip end side right side electrode Ey1 and the first root end side right side electrode Ey3 arranged in the first and second tip side right side electrodes Ey3 are reversely stretched. For this reason, if they are merged and replaced with one elongated electrode, mutual cancellation due to charges of different polarities occurs. The same applies to the first tip side left side electrode Ey2 and the first root end side left side electrode Ey4 arranged on the left side of the first plate-like bridge portion 120.

  Further, in the case of the two pairs of plate-like bridge portions 120 and 130 shown in FIG. 10, when the weight body 150 is displaced in the positive direction of the Y axis, as shown in FIG. The second tip end side right side electrode Ex1 and the second root end side right side electrode Ex3 arranged in the above are mutually stretched. For this reason, if they are merged and replaced with one elongated electrode, mutual cancellation due to charges of different polarities occurs. The same applies to the second tip end side left side electrode Ex2 and the second root end side left side electrode Ex4 arranged on the left side of the second plate-like bridge portion 130.

  From such a point, practically, a total of 12 electrically independent upper layer electrodes are arranged as in the embodiment shown in FIG. 10 (a), and the first upper layer electrode group is used as the first plate. The first root end side electrode group (Ey3, Ey4, Ez4) disposed in the vicinity of the root end portion of the bridge member 120 and the first electrode disposed in the vicinity of the tip portion of the first plate bridge portion 120 A second root end side electrode configured by the tip end side electrode group (Ey1, Ey2, Ez3), and the second upper layer electrode group disposed in the vicinity of the root end portion of the second plate-like bridge portion 130. A group (Ex3, Ex4, Ez2) and a second tip side electrode group (Ex1, Ex2, Ez1) disposed in the vicinity of the tip of the second plate-like bridge portion 130, and the first root Each of the end side electrode group, the first tip end side electrode group, the second root end side electrode group, and the second tip end side electrode group is a center electrode, It is preferable to have three types of upper layer electrodes, a right side electrode and a left side electrode.

  As described above, the operation behavior of the triaxial power generation element shown in FIG. 10 is slightly different from the operation behavior of the biaxial power generation element shown in FIG. 3, and the plate-like bridge portion 20 shown in FIG. Is not simply a combination of two. That is, as shown in FIG. 11 and FIG. 12, there is a portion where the expansion / contraction mode is reversed although it is on the same side of the plate-like bridge portion with respect to the displacement of the weight body in the X-axis direction and the Y-axis direction. To do.

  In the two-axis power generation element shown in FIG. 3, when the vibration energy in the Y-axis direction is applied, the power generation efficiency is extremely small as compared with the case where the vibration energy in the X-axis direction or the Z-axis direction is applied. However, as described above, the vibration in the Y-axis direction is performed by a deformation operation that stretches or compresses the plate-like bridge portion 20 as a whole, which is considered to be because the mechanical deformation efficiency is low. In the triaxial power generation element shown in FIG. 10, as shown in FIGS. 11 and 12, when vibration energy in the X-axis direction or the Y-axis direction is applied, in any case, the eight upper-layer electrodes Ex1 to Ex4 , Ey1 to Ey4, the charge can be extracted with sufficient efficiency.

  From such a point, it can be said that the triaxial power generation type power generation element using 12 upper electrodes shown in FIG. 10 is a power generation element with very high power generation efficiency.

<5-2 Variation of Disposing Upper Side Electrode on Side>
In §2-2, the variation of the arrangement mode of the upper layer electrode in the power generating element according to the first embodiment shown in FIG. 3 was described with reference to FIG. These variations are also applicable to the power generation element according to the second embodiment shown in FIG.

  In the side sectional view of FIG. 10 (b), the lower layer electrode E00 is disposed on the upper surface of the second plate-shaped bridge portion 130, the piezoelectric element 300 is disposed on the upper surface, and the right side electrode Ex1, the central electrode is disposed on the upper surface. An embodiment in which Ez1 and left side electrode Ex2 are arranged is shown. In this embodiment, the variation shown in FIG. 8 (a) is adopted.

  That is, in this embodiment, the lower layer electrode E00 is formed on the upper surfaces of the first plate-like bridge portion 120 and the second plate-like bridge portion 130 (in practice, the lower layer electrode E00 is formed on the entire upper surface of the basic structure 100). The piezoelectric element 300 is formed on the upper surface of the lower layer electrode E00. Further, the first center electrodes Ez3, Ez4, the first right side electrodes Ey1, Ey3, and the first left side electrodes Ey2, Ey4 are provided on the upper surface of the first plate-like bridge portion 120 with the lower layer electrode E00 and the piezoelectric element. The second central electrodes Ez1 and Ez2, the second right side electrodes Ex1 and Ex3, and the second left side electrodes Ex2 and Ex4 are formed via the element 300, and the upper surface of the second plate-shaped bridge portion 130. Are formed via the lower layer electrode E00 and the piezoelectric element 300.

  On the other hand, when the variation shown in FIG. 8B is adopted, the lower layer electrode E00 is formed on the side surfaces as well as the upper surfaces of the first plate-like bridge portion 120 and the second plate-like bridge portion 130. The piezoelectric element 300 is formed on the surface of the lower layer electrode E00. Then, the first central electrodes Ez3, Ez4 are formed on the upper surface of the first plate-like bridge portion 120 via the lower layer electrode E00 and the piezoelectric element 300, and the first right side electrodes Ey1, Ey3 and the first left electrode The side electrodes Ey2 and Ey4 may be formed on the side surface of the first plate-like bridge portion 120 via the lower layer electrode E00 and the piezoelectric element 300. Similarly, the second central electrodes Ez1, Ez2 are formed on the upper surface of the second plate-like bridge portion 130 via the lower layer electrode E00 and the piezoelectric element 300, and the second right side electrodes Ex1, Ex3 and the second The left side electrodes Ex2 and Ex4 may be formed on the side surface of the second plate-like bridge portion 130 via the lower layer electrode E00 and the piezoelectric element 300.

  On the other hand, when the variation shown in FIG. 8C is adopted, the lower layer electrode E00 is formed on the side surfaces as well as the upper surfaces of the first plate-like bridge portion 120 and the second plate-like bridge portion 130, and the piezoelectric element. 300 is formed on the surface of the lower layer electrode E00. Then, the first central electrodes Ez3, Ez4 are formed on the upper surface of the first plate-like bridge portion 120 via the lower layer electrode E00 and the piezoelectric element 300, and the first right side electrodes Ey1, Ey3 and the first left electrode The side electrodes Ey2 and Ey4 may be formed via the lower layer electrode E00 and the piezoelectric element 300 from the upper surface to the side surface of the first plate-like bridge portion 120. Similarly, the second central electrodes Ez1, Ez2 are formed on the upper surface of the second plate-like bridge portion 130 via the lower layer electrode E00 and the piezoelectric element 300, and the second right side electrodes Ex1, Ex3 and the second The left side electrodes Ex2 and Ex4 may be formed from the upper surface to the side surface of the second plate-like bridge portion 130 via the lower layer electrode E00 and the piezoelectric element 300.

  Of course, with respect to the power generating element according to the second embodiment, it is also possible to combine the upper electrode arrangement forms in the examples shown in FIGS. 8 (a) to 8 (c) for each part. It is also possible to adopt the form exemplified in (d).

  In addition, the piezoelectric element 300 does not necessarily have an integral structure, and separate and independent elements may be disposed at positions corresponding to the upper layer electrodes. However, practically, the manufacturing process becomes easier when the structure is integrated. Similarly, the lower layer electrode E00 may be separately provided at a position corresponding to each upper layer electrode. However, practically, the manufacturing process is easier if the single layer structure is used.

<5-3 Fixing part made of annular structure>
Here, as a modified example shown in FIG. 10 described in §3, an example in which the fixing portion is configured by an annular structure will be described. FIG. 18 is a plan view showing the structure of the basic structure 100I of the power generation device according to this modification, and a side sectional view (FIG. (B)) cut along the YZ plane. FIG. 18 (a) is a plan view, but in order to clearly show the planar shape, the portion inside the structure is hatched, and the positions of the 12 upper electrodes are indicated by rectangles.

  In the embodiment shown in FIG. 10, as a fixing portion for fixing one end of the first plate-like bridge portion 120 to the bottom plate 200 of the apparatus housing, a fixing portion plate shape extending along a longitudinal axis L0 parallel to the X axis. The member 110 was used. On the other hand, in the modification shown in FIG. 18, the annular structure 110I is used as the fixing portion. As shown in the figure, this annular structure 110I is a rectangular frame-shaped structure having four sides, ie, a left side 110I1, a lower side 110I2, a right side 110I3, and an upper side 110I4. As shown in FIG. Is fixed to the upper surface of the bottom plate 200I of the apparatus housing.

  On the other hand, the root end portion of the first plate-like bridge portion 120I is connected to the vicinity of the lower end of the left side 110I1 of the annular structure 110I in the drawing. And the front-end | tip part of this 1st plate-shaped bridge part 120I is connected to the root end part of the 2nd plate-shaped bridge part 130I via the intermediate connection part 125I, and the 2nd plate-shaped bridge part 130I. Is connected to the weight body 150I via the weight connection portion 140I. After all, in the case of this modification, the fixing portion is constituted by the annular structure 110I, and the first plate-like bridge portion 120I and the second plate-like bridge are formed in the inner region surrounded by the annular structure 110I. The portion 130I and the weight body 150I are arranged.

  As described above, when the structure in which the annular structure 110I surrounds the first plate-like bridge portion 120I, the second plate-like bridge portion 130I, and the weight body 150I while maintaining a predetermined distance is adopted, the annular structure body 110I serves as a stopper member that controls excessive displacement of the first plate-like bridge portion 120I, the second plate-like bridge portion 130I, and the weight body 150I. That is, even when excessive acceleration (acceleration that damages each plate-like bridge portion 120I, 130I) is applied to the weight body 150, excessive displacement of each portion can be limited, so the plate-like bridge portion 120I. , 130I can be avoided.

<5-4 Addition of heel structure>
Another feature of the modification shown in FIG. 18 is that the intermediate connection portion 125I protrudes outward from the side surface of the front end portion of the first plate-like bridge portion 120I and the second plate-like bridge portion. The ridge structure has a ridge structure portion α2 protruding outward from the side surface of the root end portion of 130I, and the weight connection portion 140I protrudes outward from the side surface of the distal end portion of the second plate-like bridge portion 130I. This is a point having a part α3. Since these flange structures α1, α2, and α3 are provided, recesses are formed in the inner portion of the annular structure 110I at positions corresponding to these flange structures α1, α2, and α3.

  The inventor of the present application has found that the power generation efficiency of the power generation element can be further improved by adopting the structure provided with the saddle structure portions α1, α2, α3 as shown in the figure. This is because if the structure provided with the flange structures α1, α2, and α3 is employed, the stretching stress at the position where each upper electrode is formed can be further increased. Let's show this based on the simulation results of structural mechanics using a computer.

  FIG. 19 (a) shows the stress generated in the plate-like bridge portions 120 and 130 when the weight body 150 is displaced in the positive X-axis direction Δx (+) in the basic structure of the power generating element shown in FIG. It is a stress distribution figure which shows the magnitude | size of. On the other hand, FIG. 19B shows the basic structure of the power generation element shown in FIG. 18 (an element adopting a structure provided with the saddle structure portions α1, α2, α3) in which the weight body 150 is displaced in the X-axis positive direction. It is a stress distribution figure which shows the magnitude | size of the stress which arises in each plate-shaped bridge part when (DELTA) x (+) is produced. In each distribution diagram, when a certain amount of displacement occurs, the areas where moderate extension stress, strong extension stress, intermediate contraction stress, and strong contraction stress are applied are shown with their own hatching. (See legend at the top right of each figure).

  Similarly, FIG. 20 shows that the weight body 150 is Y-axis positive for the basic structure (FIG. (A)) of the power generation element shown in FIG. 10 and the basic structure (FIG. (B)) of the power generation element shown in FIG. FIG. 21 is a stress distribution diagram showing the magnitude of stress generated in each plate-like bridge portion when a displacement Δy (+) in the direction is generated, and FIG. 21 is a basic structure of the power generation element shown in FIG. ) And the basic structure (FIG. (B)) of the power generation element shown in FIG. 18, the magnitude of the stress generated in each plate-like bridge portion when the weight body 150 generates the displacement Δz (+) in the Z-axis positive direction. FIG.

  Referring to the stress distribution diagrams of FIGS. 19 (a) and 19 (b) and FIGS. 20 (a) and 20 (b), when the weight body 150 is displaced in the X-axis direction or the Y-axis direction, the left and right side electrodes Ex1. It can be seen that a relatively large stretching stress is generated at the positions where .about.Ex4, Ey1 to Ey4 are formed. On the other hand, referring to the stress distribution diagrams of FIGS. 21 (a) and 21 (b), when the weight body 150 is displaced in the Z-axis direction, the formation positions of all the upper layer electrodes Ex1-Ex4, Ey1-Ey4, Ez1-Ez4 are formed. It can be seen that a relatively large stretching stress is generated. Therefore, it can be understood that the arrangement of the twelve upper layer electrodes shown in FIG. 10 is an ideal arrangement.

  In addition, in FIGS. 19 to 21, when comparing the upper diagram (a) and the lower diagram (b), in general, the stress distribution diagram shown in the lower diagram (b) generates a relatively large stretching stress. You can see that As shown in FIG. 18 (a), when a structure provided with eaves structural portions α1, α2, α3 is employed, the root end portion and the tip end portion of the first plate-like bridge portion 120I and the second plate-like shape are used. This means that stress can be efficiently concentrated on the root end portion and the tip end portion of the bridge portion 130I, and the power generation efficiency of the power generation element can be further improved. Therefore, in practice, it is preferable to employ a structure provided with the heel structure portions α1, α2, α3 as shown in FIG. 18 (a).

<5-5 Annular weight>
Subsequently, a modification example in which a weight body is provided on the outer side to form an annular structure will be described. In this modification, the roles of the fixed portion (annular structure 110I) and the weight body (150I) in the modification shown in FIG. 18 are reversed. That is, the annular structure 110I functioning as the fixing portion in the modification shown in FIG. 18 is caused to function as the weight body, and the plate-like body functioning as the weight body 150I is functioned as the fixing portion. Is. For this purpose, the lower surface of the plate-like body functioning as the weight body 150I in FIG. 18 is fixed to the upper surface of the bottom plate of the apparatus housing, and the annular structure 110I functioning as the fixing portion in FIG. In a state in which no action occurs, it may be suspended in a suspended state above the bottom plate of the apparatus housing.

  FIG. 22 is a plan view (FIG. (A)) showing a structure of a basic structure 100J of a power generating element according to a modified example in which such a role is reversed, and a side sectional view (FIG. (B)) cut along the YZ plane. )) Comparing only the plan view shown in FIG. 18A in the upper stage, the basic structure 100I shown in FIG. 18 and the basic structure 100J shown in FIG. Comparing the cross-sectional side views shown as), you can understand the difference in structure between the two.

  In the case of the basic structure 100J shown in FIG. 22, the plate-like member 150J disposed at the center serves as a plate-like fixing portion, and is a portion having a larger thickness than other portions. The lower surface of the plate-like fixing portion 150J is fixed to the upper surface of the bottom plate 200J of the apparatus housing. On the other hand, as shown in FIG. 22 (a), at the upper right corner of the plate-like fixed portion 150J, the root end portion of the first plate-like bridge portion 130J (the upper end in the figure) is connected via the fixed end connecting portion 140J. ) Is connected. Further, the root end portion (the right end in the drawing) of the second plate bridge portion 120J is connected to the tip portion (the lower end in the drawing) of the first plate-like bridge portion 130J through the intermediate connection portion 125J. Further, an annular weight body 110J is connected to the tip end portion (left end in the figure) of the second plate-like bridge portion 120J.

  As shown in FIG. 22 (a), the annular weight body 110J is a rectangular frame-like structure having four sides, that is, the left side 110J1, the lower side 110J2, the right side 110J3, and the upper side 110J4, as shown in FIG. 22 (b). Furthermore, it is suspended in the air so that it floats above the bottom plate 200J of the apparatus housing.

  In the embodiments described so far, the weight body is arranged at the inner position of the basic structure body. However, in the modification shown in FIG. 22, the annular weight body 110J is arranged at the outer position of the basic structure body 100J. Will be. If the structure in which the annular weight body is arranged on the outside as described above is adopted, it is generally easy to secure a large mass of the weight body. Therefore, the mass of the weight body is increased to increase the power generation efficiency. Above is advantageous.

<5-6 Spiral structure>
Here, a modified example in which the number of plate-like bridge portions is further increased to constitute a spiral structure will be described. FIG. 23 is a plan view showing a structure of a basic structure 100K of the power generation device according to this modification. Also in this figure, in order to clearly show the planar shape, the portion inside the structure is shown by hatching, and the positions of the 24 upper layer electrodes are shown by rectangles. In this modified example, instead of the weight connecting portion 140I in the modified example shown in FIG. 18, a third plate-like bridge portion 140K, an intermediate connecting portion 145K, a fourth plate-like bridge portion 150K, and a weight connecting portion 160K are provided. A structure for supporting the weight body 170K through the gap is adopted.

  Specifically, as shown in the drawing, a rectangular frame-shaped annular structure 110K having four sides of a left side 110K1, a lower side 110K2, a right side 110K3, and an upper side 110K4 is used as a fixing portion, and the entire lower surface of the annular structure 110K is used as the apparatus casing. It is fixed to the upper surface of the bottom plate. On the other hand, the root end portion of the first plate-like bridge portion 120K is connected to the vicinity of the lower end in the figure of the left side 110K1 of the annular structure 110K. And the front-end | tip part of this 1st plate-shaped bridge part 120K is connected to the root end part of the 2nd plate-shaped bridge part 130K via the intermediate connection part 125K, and the 2nd plate-shaped bridge part 130K. Is connected to the root end portion of the third plate-like bridge portion 140K via the intermediate connection portion 135K, and the tip portion of the third plate-like bridge portion 140K is connected to the fourth end portion via the intermediate connection portion 145K. The plate-like bridge portion 150K is connected to the root end portion, and the tip end portion of the fourth plate-like bridge portion 150K is connected to the weight body 170K via the weight connection portion 160K.

  After all, in the case of this modification, the fixing portion is constituted by the annular structure 110K, and the first plate-like bridge portion 120K and the second plate-like bridge are formed in the inner region surrounded by the annular structure 110K. The portion 130K, the third plate-like bridge portion 140K, the fourth plate-like bridge portion 150K, and the weight body 170K are arranged. Here, the first plate-like bridge portion 120K and the third plate-like bridge portion 140K extend along the first and third longitudinal axes parallel to the Y axis, and the second plate-like bridge portion. 130K and the fourth plate-like bridge portion 150K extend along second and fourth longitudinal axes parallel to the X axis. Thus, the weight body 170K is supported by a structure formed by connecting the four plate-like bridge portions 120K, 130K, 140K, and 150K in a spiral shape.

  The lower electrode is formed on the upper surface of the four plate-like bridge portions 120K, 130K, 140K, and 150K, the piezoelectric element is disposed on the upper surface, and the upper layer electrode group is locally provided at a predetermined position on the upper surface. Is the same as the previous embodiments. In the case of the illustrated example, for each of the four plate-like bridge portions 120K, 130K, 140K, and 150K, three upper layer electrodes are arranged at the root end portion and the tip end portion, and a total of 24 upper layer electrodes are formed. Has been.

  Although the structure is more complicated than the embodiments described so far, in this modification, the power generation circuit can extract power from the charges generated in the total of 24 upper layer electrodes and common lower layer electrodes. Efficiency can be improved.

  FIG. 23 shows an example in which four plate-like bridge portions 120K, 130K, 140K, and 150K are provided. Of course, only three plate-like bridge portions 120K, 130K, and 140K are provided to provide a third plate. A weight body may be directly or indirectly connected to the tip of the bridge portion 140K. Further, the weight body may be connected to the end where five or more plate-like bridge portions are connected.

  In general terms, in the structure having the first plate-like bridge portion and the second plate-like bridge portion described as the basic embodiment, between the second plate-like bridge portion and the weight body. Further, a third plate-shaped bridge portion to a K-th plate-shaped bridge portion may be provided, and a weight body may be connected to a point where a total of K plate-shaped bridge portions are connected (however, K ≧ 3). At this time, the tip of the i-th plate bridge portion (where 1 ≦ i ≦ K−1) is directly or indirectly connected to the root end portion of the (i + 1) -th plate bridge portion, and the Kth The tip of the plate-like bridge portion is directly or indirectly connected to the weight body, and the j-th plate-like bridge portion (where 1 ≦ j ≦ K) is parallel to the Y axis when j is an odd number. Extending along the jth longitudinal axis, and when j is an even number, it extends along the jth longitudinal axis parallel to the X axis.

  Further, the structure from the root end portion of the first plate-like bridge portion to the tip end portion of the K-th plate-like bridge portion forms a spiral path, and the weight body is surrounded by the spiral path. As shown in FIG. 23, the K plate bridges and the weight bodies can be efficiently arranged in a limited space as in the example shown in FIG. become. The example shown in FIG. 23 is an example in which K = 4 is set in the above general theory.

  As shown in the example shown in FIG. 23, the fixing portion is constituted by the annular structure 110K, and the first plate-shaped bridge portion to the K-th plate-shaped bridge portion and the overlap are formed in the inner region surrounded by the annular structure 110K. If the configuration in which the weight body is arranged is adopted, all structures can be efficiently accommodated in the annular structure 110K.

  If such a structure is used and a lower layer electrode, a piezoelectric element, and an upper layer electrode group are provided on the surfaces of the third plate-shaped bridge portion to the K-th plate-shaped bridge portion, the power generation circuit can generate these circuits. Electric power can be taken out from the charges generated in the upper layer electrode and the lower layer electrode, and the power generation efficiency can be improved.

  23, the intermediate connection portions 125K, 135K, 145K and the weight connection portion 160K protrude outward from the side surfaces of the end portions of the plate-like bridge portions 120K, 130K, 140K, and 150K. In addition, since the structure having the heel structure portion is adopted, an effect of increasing the stretching stress at the formation position of each upper layer electrode can be obtained.

  That is, in general terms, the tip of the i-th plate bridge portion (where 1 ≦ i ≦ K−1) and the root end portion of the (i + 1) -th plate bridge portion are the i-th intermediate connection. Are connected to each other, and when the structure in which the tip of the Kth plate-like bridge portion and the weight body are connected via the weight connection portion is adopted, the i-th intermediate connection portion is A cage structure portion that protrudes outward from the side surface of the tip portion of the i-th plate bridge portion, and the weight connection portion protrudes outward from the side surface of the tip portion of the K-th plate bridge portion. If it has a structure part, the effect which raises the expansion-contraction stress in the formation position of each upper layer electrode will be acquired, and it will become possible to perform more efficient electric power generation.

  Of course, also in the modified example shown in FIG. 23, as in the modified example described in §5-5, the annular structure 110K is used as the weight body, and the weight body 170K is used as the fixing portion, so that the roles are reversed. It is also possible.

<5-7 Addition of auxiliary weight>
Finally, a modified example will be described in which a device for adjusting the mass of the weight body is provided. As already described, in order to perform efficient power generation based on externally applied vibration, it is preferable to make the resonance frequency of the weight body coincide with the externally applied vibration frequency. For example, in the case of a dedicated power generation element to be used by being mounted on a specific vehicle, it is preferable to design from the structural design stage so that the resonance frequency matches the frequency applied from the vehicle. The simplest way to change the resonance frequency of the power generating element is to adjust the mass of the weight body. Here, an embodiment in which an auxiliary weight body is added in order to adjust the mass of the weight body of each power generating element will be described.

  FIG. 24 is a plan view (FIG. 24A) showing a modification in which the mass of the entire weight body is adjusted by adding the auxiliary weight body 150L to the basic structure 100I of the power generating element shown in FIG. FIG. 3 is a side sectional view (FIG. (B)) taken along the YZ plane. As shown in the plan view of FIG. 24 (a), the structure when the basic structure 100L according to this modification is viewed from above is exactly the same as the structure of the basic structure 100I shown in FIG. 18 (a). Here, the same reference numerals as those of the basic structure 100I shown in FIG.

  On the other hand, as can be seen from the side sectional view of FIG. 24 (b), in the basic structure 100L according to this modification, the auxiliary weight body 150L is fixed to the lower surface of the weight body 150I, and the weight body 150I. And the auxiliary weight body 150L function as a weight body in the basic structure 100L. In other words, by adding the auxiliary weight body 150L, the mass of the weight body in the basic structure 100L can be increased, and the resonance frequency can be lowered. The mass of the auxiliary weight body 150L can be adjusted by changing the material (specific gravity) and dimensions (the thickness in the Z-axis direction and the area of the projected image on the XY plane). If the material and dimensions are appropriately determined, the resonance frequency of the basic structure 100L can be adjusted to an arbitrary value.

  As described above, the method of adjusting the resonance frequency by adding the auxiliary weight body is of course applicable to any of the embodiments described so far. FIG. 25 is a plan view (FIG. 25 (a)) showing a modification in which the mass of the entire weight body is adjusted by adding auxiliary weight bodies 110M1 to 110M4 to the basic structure of the power generation element shown in FIG. This is a sectional side view (Fig. (B)) cut along the YZ plane. As shown in the plan view of FIG. 25 (a), the structure when the basic structure 100M according to this modification is viewed from above is exactly the same as the structure of the basic structure 100J shown in FIG. 22 (a). Here, the same reference numerals as those of the basic structure 100J shown in FIG.

  In the case of the embodiment shown in FIG. 25, the central plate-like member 150J is a fixed portion fixed to the apparatus housing, and the surrounding annular structure 110J (rectangular frame comprising four sides 110J1 to 110J4) is a weight. Functions as a body. Here, the mass is increased by fixing the auxiliary weight body to the lower surface of the annular structure 110J. That is, as can be seen from the side sectional view of FIG. 25 (b), in the basic structure 100M according to this modification, auxiliary weight bodies 110M1 to 110M4 are respectively provided on the lower surfaces of the sides 110J1 to 110J4 of the annular structure. The assembly of the annular weight body 110J and the auxiliary weight bodies 110M1 to 110M4 functions as a weight body in the basic structure body 100M. Accordingly, it is possible to increase the mass of the weight body and lower the resonance frequency.

  In the illustrated example, the auxiliary weight bodies 110M1 to 110M4 are provided on all four sides 110J1 to 110J4 of the annular weight body 110J. However, the auxiliary weight body may be provided only on the lower surface of a specific side. It doesn't matter. However, in order to position the center of gravity of the entire weight body in the vicinity of the origin O and perform balanced and stable vibration, the auxiliary weight body is equally distributed over all four sides 110J1 to 110J4 as in the illustrated example. It is preferable to add. The mass of the auxiliary weight body can be adjusted by changing the thickness in the Z-axis direction.

  Since various materials can be used as the auxiliary weight body, it is possible to select an appropriate material according to the necessity of mass adjustment. For example, if it is necessary to make fine adjustments, use a material with a low specific gravity such as aluminum or glass. If it is necessary to increase the mass significantly, use a material with a high specific gravity such as tungsten. That's fine.

  In practical use, a general-purpose product having a standard resonance frequency suitable for the most general usage environment is mass-produced using the basic structure 100I shown in FIG. 18 and the basic structure 100J shown in FIG. An auxiliary weight body having an appropriate mass is added to a general-purpose product to form a basic structure 100L shown in FIG. 24 or a basic structure 100M shown in FIG. It is only necessary to provide custom-made products with frequencies. By doing so, it is possible to provide tailor-made products that are optimal for individual use environments, while reducing costs by mass-producing general-purpose products.

  In the examples shown in FIGS. 24 and 25, the auxiliary weight body is provided on the lower surface of the original weight body. However, the auxiliary weight body is provided on the upper surface and the side surface of the original weight body. It is also possible to provide it. However, if the auxiliary weight body is provided on the lower surface of the original weight body, the auxiliary weight body can be accommodated in a space formed between the bottom plate of the device housing, so that space saving can be achieved. As in the illustrated example, it is preferably provided on the lower surface of the original weight body.

  As described above, the method for improving the power generation efficiency by adding the auxiliary weight body to the weight body and adjusting the resonance frequency to the frequency of the usage environment has been described. Since the mass of the entire weight body is increased by adding the body, the effect of improving the power generation efficiency can be obtained.

10: fixed part 20: plate-like bridge part 30: weight body 40: bottom plates 50, 50B, 50C of the device housing: piezoelectric elements 51D, 52D: piezoelectric elements 60: power generation circuits 100, 100A to 100M: basic structure 110 , 110AB to 110GH: plate member 110I for fixed part, 110K: annular structure 110I1 to 110I4: each side 110J of the annular structure: annular weight 110J1 to 110J4: each side 110K of the annular weight: annular structure 110K1 to 110K4: Sides 110M1 to 110M4 of the annular structure: auxiliary weight bodies 120, 120A to 120K: first plate-like bridge portion 120J: second plate-like bridge portions 125, 125I, 125J, 125K: intermediate connection Portions 130, 130A to 130K: second plate-like bridge portion 130J: first plate-like bridge portion 135K: intermediate connection portions 140, 140I: heavy Connection portion 140J: Fixed end connection portion 140K: Third plate-like bridge portion 145K: Intermediate connection portions 150, 150A to 150I: Weight body 150J: Plate-like fixing portion 150K: Fourth plate-like bridge portion 150L: Auxiliary weight Weight body 160K: Weight connection portion 170K: Weight bodies 200, 200I, 200J: Bottom plate 300 of the apparatus housing 300: Piezoelectric element 400: Cover 410 of the apparatus housing: Top plate 420 of the apparatus housing: Side plate of the apparatus housing 500: Power generation circuit 1000: Basic structure of power generation device 2000: Basic structure of power generation device Cf: Capacitance element (capacitor)
D11 (+) to D13 (+): Positive charge rectifier (diode)
D11 (-) to D13 (-): negative charge rectifier (diode)
D0 (+), Dx1 (+) to Dz24 (+): Positive charge rectifier (diode)
D0 (−), Dx1 (−) to Dz24 (−): negative charge rectifier (diode)
E0, E0B, E0C, E0D, E00: Lower layer electrode E11: Right side electrode on weight side E12: Center electrode on weight side E13: Left side electrode E21, E21B, E21C, E21D on weight side Right side electrodes E22, E22B, E22C, E22D: Center electrode E23, E23B, E23C, E23D on the fixed part side: Left side electrode E31 on the fixed part side: Right side electrode E32: Center electrode E33: Left side electrode Ex1: Second Tip side right side electrode Ex2: second tip side left side electrode Ex3: second root end side right side electrode Ex4: second root end side left side electrode Ey1: first tip side Right side electrode Ey2: First tip side left side electrode Ey3: First root end side right side electrode Ey4: First root end side left side electrode Ez1: Second tip side central electrode Ez2: Second root end side center electrode Ez3: first tip end side center Pole EZ4: first root end side central electrode L0: longitudinal axis Lx fixed part: second longitudinal axis (center line)
Ly: first longitudinal axis (center line)
O: origin P11 to P23 of the three-dimensional coordinate system: parts Px1 to Pz4 of the piezoelectric element 50: parts Rd1, Rd2 of the piezoelectric element 300: resistance element V: gap X: coordinate axis Δx (+) of the three-dimensional coordinate system : X-axis positive displacement Y: Three-dimensional coordinate system coordinate axis Δy (+): Y-axis positive displacement Z: Three-dimensional coordinate system coordinate Δz (+): Z-axis positive displacement ZL: Load α1 α3: ridge structure

Claims (10)

A power generating element that generates power by converting vibration energy into electrical energy,
When defining a first axis and a second axis that intersect on a predetermined reference plane,
A first member extending from the root end to the tip along the first axis;
A second member connected to the tip of the first member and extending along the second axis;
A weight body directly or indirectly connected to the second member;
An apparatus housing that houses the first member, the second member, and the weight body;
A fixing portion for fixing the root end portion of the first member to the device housing;
A lower layer electrode formed in a layer on at least the surface of the first member;
A piezoelectric element formed in a layer on the surface of the lower electrode, and an upper electrode group consisting of a plurality of upper electrodes locally formed on the surface of the piezoelectric element;
A power generation circuit that rectifies a current generated based on charges generated in the upper layer electrode and the lower layer electrode to extract electric power;
With
At least the first member has flexibility, and the weight body is connected to the fixed portion via the first member and the second member;
When an external force that vibrates the device casing is applied, the weight body is configured to vibrate within the device casing by at least the bending of the first member;
The piezoelectric element has the property of causing polarization in the thickness direction by the action of stress that expands and contracts in the layer direction,
The upper layer electrode group includes a tip-side right side electrode and a tip-side left side electrode disposed in the vicinity of the tip of the first member, and a root tip disposed in the vicinity of the root end of the first member. has a part-side right side electrodes and apical side left side electrode, each of these upper electrodes are arranged so as to extend along the first axis, the lower electrode across the piezoelectric element Facing a predetermined area,
When the center line along the first axis and the right side and the left side with respect to the center line are defined in the first member, the tip side right side electrode is located on the right side of the center line. Are arranged so as not to protrude to the left side of the center line, and the tip side left side electrode protrudes to the left side of the center line and to the right side of the center line. The root end side right side electrode is arranged on the right side of the center line so as not to protrude to the left side of the center line, and the root end The power generation element is characterized in that the part-side left side electrode is arranged on the left side of the center line so as not to protrude to the right side of the center line. The power generating element according to claim 1,
  The first axis and the second axis are axes orthogonal on the reference plane;
  A power generating element, wherein a tip end portion of a first member and a side portion of a second member are connected, and the first member and the second member are T-shaped in the vicinity of the connecting portion. The power generating element according to claim 1 or 2,
  The fixing portion is configured by an annular structure disposed along the reference plane, and the first member, the second member, and the weight body are disposed in an inner region surrounded by the annular structure. ,
  The distance between the inner surface of the annular structure and the facing surface of the first member and the distance between the inner surface of the annular structure and the facing surface of the second member are Even when an excessive acceleration is applied such that the first member or the second member is damaged, the annular structure is set at a distance that can prevent the damage by restricting an excessive displacement of each part. A power generating element, wherein the body serves as a stopper member for controlling excessive displacement. In the electric power generating element according to claim 3,
  Even if the distance between the inner surface of the annular structure and the weight body is excessively accelerated such that the first member or the second member is damaged with respect to the weight body, The power generating element is characterized in that it is set at a distance that can limit the excessive displacement and avoid the damage. The roles of the fixing portion and the weight body in the power generation element according to any one of claims 1 to 4 are reversed, and the fixing member functioning as the fixing portion in the power generation element is functioned as the weight body, In order to make the weight member that functioned as the weight body in the power generating element function as the fixing portion, the lower surface of the weight member is fixed to the upper surface of the bottom plate of the apparatus housing, and the fixing member acts on the external force. A power generating element characterized by being suspended in a suspended state above the bottom plate of the apparatus housing in a state where no power is applied. In the electric power generating element in any one of Claims 1-5,
A lower layer electrode is formed on the upper surface of the first member , and a piezoelectric element is formed on the upper surface of the lower layer electrode,
The power generating element, wherein the upper electrode group includes an upper electrode locally formed on the upper surface of the first member via the lower electrode and the piezoelectric element. In the electric power generating element in any one of Claims 1-5,
The lower layer electrode is formed on the side surface together with the upper surface of the first member , and the piezoelectric element is formed on the surface of the lower layer electrode.
The power generating element, wherein the upper electrode group includes an upper electrode formed on the side surface of the first member via the lower electrode and the piezoelectric element. In the electric power generating element in any one of Claims 1-5,
The lower layer electrode is formed on the side surface together with the upper surface of the first member , and the piezoelectric element is formed on the surface of the lower layer electrode.
An upper layer electrode group includes an upper layer electrode formed through the lower layer electrode and the piezoelectric element from the upper surface to the side surface of the first member . In the electric power generating element in any one of Claims 1-8,
The power generating element, wherein the first member and the second member are constituted by an integral structure obtained by processing the same plate-like member. In the electric power generating element in any one of Claims 1-9,
A positive charge rectifying element in which the power generation circuit has a forward direction from each upper layer electrode to the positive electrode side of the capacitive element in order to guide the positive charge generated in the capacitive element and each upper layer electrode to the positive electrode side of the capacitive element. And a negative charge rectifying element having a forward direction from the negative electrode side of the capacitive element to each upper layer electrode to guide the negative charge generated in each upper layer electrode to the negative electrode side of the capacitive element, A power generating element characterized in that electric energy converted from vibration energy is supplied by being smoothed by the capacitor element.

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