Vibration power generation device

Abstract

To provide a vibration power generation device whose size can be kept as small as possible. [Solution] A bridge circuit (15) is configured inside or outside the substrate and is electrically connected to a fixed electrode portion. A movable electrode portion (20) is disposed facing the fixed electrode portion at a distance from the fixed electrode portion and vibrates relative to the fixed electrode portion. A power storage device (60) is electrically connected to the output of the bridge circuit (15) and outputs a voltage. The power storage device (60) is configured as a weight on the movable electrode portion (20) and vibrates integrally with the movable electrode portion (20).

Description

[Technical Field]

[0001] The present invention relates to a vibration power generation device. [Background technology]

[0002] This type of vibration-powered device converts mechanical vibration energy into electricity. The vibration-powered device itself, created using the MEMS process, is small and light. For this reason, it is common to increase the device's weight by placing a weight on the vibrating movable electrode.

[0003] Furthermore, since the output of a vibration power generation device is AC, it is converted to DC output by attaching an external bridge circuit and a power storage device including a capacitor. The vibration power generation device, the external bridge circuit, and the power storage device make the device bulky. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 06792249 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide a vibration power generation device that can be kept as small as possible. [Means for solving the problem]

[0006] The invention described in claim 1 comprises a substrate, a bridge circuit, a movable electrode portion, and an electricity storage device. The bridge circuit is configured inside or outside the substrate and is electrically connected to the fixed electrode portion. The movable electrode portion is disposed facing the fixed electrode portion at a distance and vibrates relative to the fixed electrode portion. The electricity storage device is electrically connected to the output of the bridge circuit and outputs a voltage. The electricity storage device is configured as a weight on the movable electrode portion and vibrates integrally with the movable electrode portion. According to the invention described in claim 1, since the electricity storage device is configured to vibrate integrally with the movable electrode portion, the size can be kept as small as possible. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a longitudinal cross-sectional view schematically illustrating the structure of a vibration power generation device according to a first embodiment. [Figure 2] FIG. 1 is a top view schematically illustrating a vibration power generation device according to a first embodiment. [Figure 3] FIG. 1 is a perspective view schematically illustrating the structure of a vibration power generation device according to a first embodiment. [Figure 4] Electrical configuration diagram of the vibration power generation device in the first embodiment [Figure 5] FIG. 10 is a perspective view schematically illustrating the structure of a vibration power generation device according to a second embodiment. [Figure 6] Electrical configuration diagram of a vibration power generation device according to a second embodiment [Figure 7] FIG. 10 is a longitudinal cross-sectional view schematically illustrating the structure of a vibration power generation device according to a third embodiment. [Figure 8] FIG. 10 is a perspective view schematically illustrating the structure of a vibration power generation device according to a third embodiment. [Figure 9] FIG. 10 is a perspective view schematically illustrating the structure of a vibration power generation device according to a fourth embodiment. [Figure 10] FIG. 10 is a perspective view schematically illustrating the structure of a vibration power generation device according to a fifth embodiment. [Figure 11] FIG. 13 is a longitudinal cross-sectional view schematically illustrating the structure of a portion of a vibration power generation device according to a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Below, several embodiments of the vibration power generation device will be described. Parts that perform the same function in each embodiment will be assigned the same reference numerals, and their description may be omitted. In the drawings, the X, Y, and Z directions will be shown as directions that intersect with each other. The X direction corresponds to the first axis direction, the Y direction corresponds to the second axis direction, and the Z direction corresponds to the third axis direction. From a structural standpoint, it is desirable for the X, Y, and Z directions to intersect at right angles, but this is not a limitation.

[0009] (First embodiment) The first embodiment will be described with reference to Figures 1 to 4. The vibration power generation device 1 constitutes a MEMS mounted on a vehicle, and as shown in Figure 1, mainly comprises a fixed electrode section 10, a movable electrode section 20, a spacer 30, a peripheral support section 40, and sections that function as a flexible section 50.

[0010] As shown in FIG. 1, the fixed electrode unit 10 includes fixed electrodes 13 on a substrate 11 with an insulating film 12 interposed therebetween. The substrate 11 is made of, for example, a silicon substrate. The insulating film 12 is made of, for example, silicon oxide. The fixed electrodes 13 are made of a conductive material such as gold or aluminum. The fixed electrodes 13 are configured on the surface of the insulating film 12 on the substrate 11 and are periodically arranged in the X direction.

[0011] The fixed electrode portion 10 is formed on the first layer L1. As shown in the upper diagram of Fig. 2, the fixed electrode 13 includes a first comb-tooth structure 13a in which one end of every other linear portion 13aa formed in a stripe shape along the Y direction is joined, and a second comb-tooth structure 13b in which the other end of every other linear portion 13bb that does not form part of the linear portion 13aa of the first comb-tooth structure 13a is joined. The linear portions 13aa and 13bb of the fixed electrode 13 are elongated in the Y direction, which is a direction intersecting the X direction in which the movable electrode portion 20 can vibrate.

[0012] The linear portion 13bb of the second comb tooth structure 13b is arranged opposite the linear portion 13aa of the first comb tooth structure 13a, and the first comb tooth structure 13a and the second comb tooth structure 13b are configured separately on the substrate 11 with an insulating film 12 interposed between them.

[0013] That is, the electrodes of the first comb-tooth structure 13a and the electrodes of the second comb-tooth structure 13b adjacent to each other are configured with different wirings in the fixed electrode 13. The first comb-tooth structure 13a and the second comb-tooth structure 13b are electrically connected to the outside using at least two systems of wiring.

[0014] 1 and 2, the spacers 30 are positioned at the four corners of the XY plane of the rectangular substrate 11. As shown in Fig. 1, the spacers 30 are positioned between the outer peripheral support portion 40 and the fixed electrode portion 10, and as a result, are configured to support the outer peripheral support portion 40 from below in the Z direction.

[0015] The movable electrode section 20 is formed on the second layer L2. The second layer L2 is located above the first layer L1 (see FIG. 1). As shown in the lower diagram of FIG. 2, the electret electrodes 23 are spaced apart from one another in the X direction and arranged in stripes along the Y direction. As shown in FIG. 1, the movable electrode section 20 is integrally connected to the outer periphery support section 40 via a flexible section 50. The electret electrodes 23 are configured to be long in the Y direction, which is a direction intersecting the X direction in which the movable electrode section 20 can vibrate.

[0016] The peripheral support section 40 and the flexible sections 50 are configured on the second layer L2. As shown in FIG. 1, the pair of flexible sections 50 are arranged symmetrically in the X direction with the X-direction center of the peripheral support section 40 as the center, and are connected to the peripheral support section 40. As shown in FIG. 3, the peripheral support section 40 is configured in the shape of a rectangular frame in the X and Y directions. Although the flexible sections 50 are not shown in FIG. 3, as shown in FIG. 1, the peripheral support section 40 is configured to support the pair of flexible sections 50 from the X-direction end sections toward the X-direction center.

[0017] The flexible section 50 is flexible in the X direction and can deform in the X direction while supporting the movable electrode section 20. Because the flexible section 50 supports the movable electrode section 20, it deforms and bends in the X direction when subjected to an external force, causing the movable electrode section 20 to vibrate in the X direction. The movable electrode section 20 is disposed opposite the fixed electrode section 10 at a distance in the Z direction and is configured to vibrate relative to the fixed electrode section 10.

[0018] 1 and 3, the upper surface of the movable electrode portion 20 is configured to be flat, and an electricity storage device 60 is placed as a weight on the movable electrode portion 20. The electricity storage device 60 includes an electricity storage body 61 and terminals 60a, 60b, and is configured to store electricity from the terminals 60a, 60b in the electricity storage body 61 and to discharge electricity to the outside from the terminals 60a, 60b.

[0019] The power storage device 60 is configured by a ceramic capacitor, an electrolytic capacitor, an electric double layer capacitor, a lithium ion battery, a silicon capacitor, etc. If the power storage device 60 is configured by, for example, a silicon capacitor, the temperature characteristics and bias dependency characteristics are reduced compared to the case of a ceramic capacitor or an electrolytic capacitor, and the power storage device 60 is suitable for a harsher environment.

[0020] The type of the electricity storage device 60 mounted on the upper surface of the movable electrode section 20 is not limited to one of the types listed above, and may be two or more types. The electricity storage device 60 is desirably arranged so as to fit inside the outer shape of the movable electrode section 20 in the XY plane, for example, but the electricity storage device 60 may be mounted in any manner as long as it is mounted on the movable electrode section 20.

[0021] The first comb-tooth structure 13a and the second comb-tooth structure 13b of the fixed electrode portion 10 described above are electrically connected to the pads 61a and 61b shown in Fig. 3 using at least two wiring systems (not shown). The pads 61a and 61b are each disposed on the upper surface of the outer peripheral support portion 40 and connected to the bridge circuit 15 via bonding wires.

[0022] The bridge circuit 15 is configured inside or outside the substrate 11, and as described above, is electrically connected to the first comb-tooth structure 13a and the second comb-tooth structure 13b of the fixed electrode portion 10. As shown in Fig. 4, the electrical configuration of the bridge circuit 15 is a full bridge circuit in which diodes D1, D2, D3, and D4 are combined in the illustrated configuration. In the example shown in Fig. 4, the anodes of diodes D1 and D2 are connected in common, and the cathodes of diodes D3 and D4 are connected in common.

[0023] The cathode of diode D1 and the anode of diode D3 are connected together, and this common connection point is connected to a pad 61a of a first comb-tooth structure 13a that constitutes the fixed electrode portion 10. On the other hand, the cathode of diode D2 and the anode of diode D4 are connected together, and this common connection point is connected to a pad 61b of a second comb-tooth structure 13b that constitutes the fixed electrode portion 10.

[0024] The substrate 21 of the movable electrode portion 20 is connected to the commonly connected anodes of the diodes D1 and D2 and to one terminal (e.g., 60b) of the electricity storage device 60, and is connected to a ground node. The substrate 21 corresponds to a second substrate. The commonly connected cathodes of the diodes D3 and D4 are connected to the other terminal (e.g., 60a) of the electricity storage device 60. The voltage between the terminals 60a and 60b of the electricity storage device 60 is supplied to a load. In addition to the structure described above, the bridge circuit 15 may be formed on the substrate 21 on which the movable electrode portion 20 is disposed.

[0025] The power generation action of the above-described configuration will now be described. When the movable electrode portion 20 vibrates in the X direction, the electret electrode 23 vibrates / reciprocates in the X direction above the first comb-tooth structure 13a and the second comb-tooth structure 13b of the fixed electrode 13. As a result, the overlapping area of ​​the electret electrode 23 and the fixed electrode 13 in the X direction increases or decreases, and the overlapping area between the electret electrode 23 and the fixed electrode 13 increases or decreases. This changes the amount of charge induced in the fixed electrode 13.

[0026] For example, if the electret electrode 23 is negatively charged and the fixed electrode 13 is positively charged, when the opposing area between the electret electrode 23 and the fixed electrode 13 increases or decreases, the positive charges on the linear portions 13aa and 13bb of the fixed electrode 13 move.

[0027] For example, when the opposing area between the electret electrode 23 and the line portion 13aa increases, the opposing area between the electret electrode 23 and the line portion 13bb decreases. In this case, the positive charge on the fixed electrode 13 is attracted to the negative charge on the electret electrode 23 and moves to the line portion 13aa.

[0028] Conversely, when the opposing area between the electret electrode 23 and the line portion 13bb increases, the opposing area between the electret electrode 23 and the line portion 13aa decreases. In this case, the positive charge on the fixed electrode 13 is attracted to the negative charge on the electret electrode 23 and moves to the line portion 13bb. This causes a generated current to flow through the fixed electrode 13, and the generated current can be stored in the electricity storage device 60 through the bridge circuit 15. As a result, power can be supplied to a load through the electricity storage device 60.

[0029] <Summary of this embodiment> Conventionally, configuring the capacitor of the power storage device 60 as an external circuit is not preferable because it takes up a large mounting area. In contrast, according to this embodiment, the power storage device 60 is configured as a weight on top of the movable electrode section 20 and is configured to vibrate integrally with the movable electrode section 20. Because the power storage device 60 is configured to vibrate integrally with the movable electrode section 20, it is possible to keep the size as small as possible.

[0030] In particular, the integration of the electricity storage device 60 into the vibration power generation device 1 increases the effective mass of the movable electrode unit 20. This increases the mechanical energy of the movable electrode unit 20, thereby increasing the amount of power generation.

[0031] Moreover, the bridge circuit 15 is also integrated into the vibration power generation device 1, making it possible to achieve a more compact configuration. In other words, users of this vibration power generation device 1 can use the device 1 like a battery.

[0032] (Second embodiment) The second embodiment will be described with reference to Figures 5 and 6. The same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof will be omitted.

[0033] The bridge circuit 215 of this embodiment is configured by a circuit in which a diode D1 is connected in series to the power storage device 60. The bridge circuit 215 may be configured by a half-bridge circuit. As shown in FIGS. 5 and 6 , the pad 61a is electrically connected to the first comb-tooth structure 13a and the anode of the diode D1 through wiring (not shown), and the cathode of the diode D1 is connected to one terminal 60b of the power storage device 60 through a bonding wire. The pad 61b is electrically connected to the second comb-tooth structure 13b and the other terminal 60a of the power storage device 60 through wiring (not shown). Even with this structure, the power storage device 60 functions as a weight on the movable electrode portion 20, and the same effects as those of the above-described embodiment can be achieved.

[0034] (Third embodiment) The third embodiment will be described with reference to Fig. 7 and Fig. 8. Fig. 7 and Fig. 8 show the structure of an electricity storage device 360 ​​in a vibration power generation device 301. The electricity storage device 360 ​​has a structure in which electricity storage devices 60, each of which is made up of an electricity storage body 61 and terminals 60a, 60b, are stacked in multiple stages, and is configured on a third layer L33.

[0035] In this case, the terminals 60a, 60b of the multiple stages of the power storage devices 60 are stacked in contact with each other between the top and bottom, thereby enabling electrical parallel connection. The rest of the configuration of the first layer L1 and the second layer L2 is the same as in the above-described embodiment, and therefore description thereof will be omitted.

[0036] For example, if the power storage device 360 ​​is constructed by stacking multiple silicon capacitors, each layer can be constructed to have a capacitance of approximately several microfarads, and the stack height can be constructed to be as thin as approximately 100 micrometers. Therefore, as shown in Figures 7 and 8, even when multiple layers are stacked, the stack height can be constructed to be thin, and it is advisable to adjust the number of layers depending on the required capacity.

[0037] If the energy storage devices 60 are stacked in multiple layers on the movable electrode portion 20 while electrically connected in parallel, they will be heavier as weights compared to the above-described embodiment, which will increase the amount of power generated and also increase the stored power of the entire energy storage device 360.

[0038] (Fourth embodiment) The fourth embodiment will be described with reference to FIG. 9. FIG. 9 shows an example of mounting a plurality of power storage devices 60 on a vibration power generation device 401. A plurality of power storage devices 60 are mounted directly on the upper surface of the movable electrode section 20. Adjacent terminals 60a and terminals 60b of these power storage devices 60 are electrically connected to each other using bonding wires. Even in this structure, the power storage devices 60 are electrically connected in parallel. Therefore, the same effects as those of the third embodiment can be achieved.

[0039] (Fifth embodiment) The fifth embodiment will be described with reference to Fig. 10. When an electret electrode 23 with a relatively high surface potential is used, the output voltage of the fixed electrode unit 10 becomes high. If it is expected that the output voltage of the fixed electrode unit 10 will exceed the withstand voltage of the electricity storage devices 60, it is advisable to configure a structure in which the electricity storage devices 60 are electrically connected in series.

[0040] For example, Fig. 10 shows an example of a connection configuration of power storage devices 60 in a vibration power generation device 501. As shown in Fig. 10, a plurality of power storage devices 60 may be directly arranged on the upper surface of the movable electrode section 20, and adjacent terminals 60b-60b of the power storage devices 60 may be connected by a bonding wire, and the terminal 60a at the other end of one of the power storage devices 60 to be connected may be connected to the terminal 60a of another power storage device 60 by a bonding wire.

[0041] This allows the power storage devices 60 to be electrically connected in series, thereby increasing the withstand voltage. Furthermore, these power storage devices 60 function as weights, but since multiple power storage devices 60 are mounted on the movable electrode section 20, the weight becomes relatively heavy. This also increases the amount of power generation.

[0042] (Sixth embodiment) The sixth embodiment will be described with reference to Fig. 11. Fig. 11 shows a schematic vertical cross-sectional view of the stacked structure of an electricity storage device 60 in a vibration power generation device 601. In Fig. 11, the configuration of the fixed electrode unit 10 is omitted because it is the same as in the previous embodiments. The electricity storage device 60 has a structure in which multiple layers are stacked and electrically connected in series.

[0043] The power storage device 60 has a terminal 60a at one end and a terminal 60b at the other end. A plurality of power storage devices 60 can be electrically connected in series by connecting the terminals 60a, 60b in a stacked manner. As a result, similar to the fifth embodiment, the withstand voltage of the power storage device 60 can be increased, and the weight that functions as a weight also increases, thereby increasing the amount of power generation.

[0044] (Other embodiments) The present invention is not limited to the above-described embodiment, and the following modifications or extensions are possible. The structure has been described in which the electret electrode 23 is used and applied to the electrostatic coupling type vibration power generation devices 1, 301, 401, 501, and 601, but the present invention is not limited to this and may also be applied to an inductive coupling type vibration power generation device.

[0045] For ease of explanation, the fixed electrode 13 is named as the fixed electrode 13, but is not limited to this, and does not have to be fixed as long as it is an electrode that vibrates by changing its relative position with respect to the electret electrode 23 so that the facing area changes relative to the electret electrode 23.

[0046] Although the present disclosure has been described based on the above-described embodiment, it is understood that the present disclosure is not limited to the embodiment or the structure described in the embodiment. The present disclosure also encompasses various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure. [Explanation of symbols]

[0047] In the drawings, 1, 301, 401, 501, and 601 indicate vibration power generation devices, 10 indicates a fixed electrode portion (electrode), 11 indicates a substrate, 15 indicates a bridge circuit, 20 indicates a movable electrode portion, 21 indicates a substrate (second substrate), and 60 and 360 indicate electricity storage devices.

Claims

1. a substrate (11) on which an electrode (10) is disposed; a bridge circuit (15) formed inside or outside the substrate and electrically connected to the electrodes; a movable electrode portion (20) disposed opposite to and spaced from the electrode and vibrating relatively to the electrode; an electricity storage device (60, 360) electrically connected to the output of the bridge circuit and outputting a voltage; The power storage device is a vibration power generation device configured as a weight on the movable electrode portion and vibrating integrally with the movable electrode portion.

2. 2. The vibration power generation device according to claim 1, wherein the bridge circuit is a full-bridge circuit or a half-bridge circuit using diodes.

3. The vibration power generation device according to claim 1 or 2, wherein the bridge circuit is formed on the base material on which the electrodes are arranged or on a second base material on which the movable electrode portion is arranged.

4. The vibration power generation device according to claim 1 , wherein the power storage device has a structure in which a plurality of layers are stacked and electrically connected in parallel.

5. The vibration power generation device according to claim 1 , wherein the power storage device has a structure in which a plurality of layers are stacked and electrically connected in series.

6. The vibration power generation device according to claim 1 , wherein the power storage device is a silicon capacitor.

7. The vibration power generation device according to any one of claims 1, 4, and 5, which is configured using an electret electrode (23).

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