Vibration power generation element and vibration power generation device

Abstract

In a vibration power generation element that uses vibration from the outside to output alternating current from an output line, there is provided: an intermediate electrode that is not connected to the output line; a plurality of electret electrodes that are arranged opposite to the intermediate electrode and have an electret on at least a portion of the surface of the surface opposite to the intermediate electrode; a holding portion that holds the intermediate electrode and the plurality of electret electrodes so that they can vibrate freely relative to each other; and a charge injector that injects charges having opposite characteristics to those of the electrets formed on the surfaces of the plurality of electret electrodes into the intermediate electrode.

Description

Technical Field

[0001] The present invention relates to a vibration power generation element and a vibration power generation device. Background Art

[0002] As one of the energy harvesting technologies for obtaining energy from environmental vibrations, it is known that a method of using a MEMS (Micro electromechanical Systems) vibration element, i.e., a vibration power generation element, to generate electricity based on environmental vibrations. The vibration power generation element itself is an element that has a piezoelectric element and an electrostatic capacitive element, and generates an alternating current equal to the frequency of the environmental vibration when it is vibrated at the frequency of the environmental vibration. The electrostatic induction vibration power generation element generates electricity using the induced charge generated by the mutual vibration of multiple electrodes (for example, refer to Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-228283 Summary of the invention

[0006] Problems to be solved by the invention

[0007] Since the vibration energy of environmental vibration is weak, a vibration power generation element is required that can convert the environmental vibration into electrical energy with high efficiency.

[0008] Solutions to Solve Problems

[0009] The vibration power generation element of the first scheme is a vibration power generation element that uses vibration from the outside to output alternating current from an output line, and includes: an intermediate electrode that is not connected to the above-mentioned output line; a plurality of electret electrodes that are arranged opposite to the above-mentioned intermediate electrode and have an electret on at least a portion of the surface of the surface opposite to the above-mentioned intermediate electrode; a holding portion that holds the above-mentioned intermediate electrode and the above-mentioned plurality of electret electrodes so that they can vibrate freely relative to each other; and a charge injector that injects charges with opposite characteristics to the electrets formed on the surfaces of the above-mentioned plurality of electret electrodes into the above-mentioned intermediate electrode.

[0010] The vibration power generating element according to a second aspect is the vibration power generating element according to the first aspect, wherein the direction of the relative vibration is preferably a direction parallel to the surfaces of the plurality of electret electrodes facing the intermediate electrode.

[0011] The vibration power generation element of the third scheme is based on the vibration power generation element of the second scheme. Preferably, if the intermediate electrode moves relative to the multiple electret electrodes in a first direction through the above-mentioned relative vibration, the area of ​​the opposing part between one of the multiple electret electrodes and the intermediate electrode increases, and the area of ​​the opposing part between another of the multiple electret electrodes and the intermediate electrode decreases. If it moves in a second direction different from the above-mentioned first direction, the area of ​​the opposing part increases or decreases opposite to the movement in the first direction.

[0012] The vibration power generating element of a fourth aspect is the vibration power generating element according to any one of the first to third aspects, wherein the charge injector preferably connects a part of a circuit that receives power supply from the vibration power generating element to the intermediate electrode.

[0013] The vibration power generation element of the 5th scheme is based on the vibration power generation element described in any one of the 1st to 3rd schemes, and preferably the above-mentioned charge injector includes a resistance element, one end of the above-mentioned charge injector is connected to the above-mentioned intermediate electrode, and the other end is connected to at least one of the above-mentioned multiple electret electrodes.

[0014] The vibration power generating element of the sixth aspect is the vibration power generating element according to the fourth or fifth aspect, and preferably comprises a control component that controls the injection of charges by the charge injector into the intermediate electrode.

[0015] A vibration power generating device according to a seventh aspect comprises: the vibration power generating element according to any one of the first to sixth aspects; and a power supply device.

[0016] Effects of the Invention

[0017] According to the present invention, the energy of environmental vibration can be converted into electric energy with high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a diagram showing the structure of a vibration power generating element 10 according to an embodiment of the present invention and a vibration power generating device 100 including the vibration power generating element 10 .

[0019] Figure 2 It is a diagram for explaining the operating principle of the vibration power generating element 10 according to the embodiment. Figure 2 (a) to (c) are diagrams showing charges induced by the electret electrode 11 and the intermediate electrode 12 at respective relative positions of the intermediate electrode 12 with respect to the electret electrode 11 .

[0020] Figure 3 This is a diagram for explaining one form of the operation when the intermediate electrode 12 is neutralized. Figure 3(a) to (c) are diagrams showing charges induced by the electret electrode 11 and the intermediate electrode 12 at respective relative positions of the intermediate electrode 12 with respect to the electret electrode 11 .

[0021] Figure 4 It is a diagram showing a vibration power generating element 10 a according to Modification 1.

[0022] Figure 5 It is a diagram showing a vibration power generating element 10 b according to Modification 2.

[0023] Figure 6 It is a diagram showing a vibration power generating element 10 c according to Modification 3.

[0024] Figure 5 (a) is a top view of the vibration power generating element 10c. Figure 5 (b) Observed from -Y direction Figure 5 (a) is a cross-sectional view of the BB section.

[0025] Figure 7 It is a diagram showing a vibration power generating element 10 d according to a fourth modification.

[0026] Figure 8 1 and 2 are diagrams showing the structure of a vibration power generating element 10 e according to Modification 5 and a vibration power generating device 100 b including the vibration power generating element 10 e .

[0027] Fig. 9 It is a diagram showing the structure of a vibration power generating element 10f according to Modification Example 6. DETAILED DESCRIPTION

[0028] (Implementation Method)

[0029] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 1 is a diagram showing a vibration power generating device 100 having a vibration power generating element 10 according to an embodiment of the present invention. The vibration power generating device 100 includes the vibration power generating element 10 and a power supply device 40. The electrostatic capacitance type vibration power generating element 10 includes a first electret electrode 11a, a second electret electrode 11b, and an intermediate electrode 12 disposed between the two electret electrodes 11a and 11b.

[0030] The first electret electrode 11 a is fixed to the support frame 13 , and an electret 15 a having a negative charge is formed on the surface of the first electret electrode 11 a facing the intermediate electrode 12 , for example.

[0031] The second electret electrode 11 b is also fixed to the support frame 13 , and an electret 15 b having a negative charge is formed on the surface of the second electret electrode 11 b facing the intermediate electrode 12 as an example.

[0032] The electrets 15 a and 15 b are formed by performing a known charging process described in, for example, Japanese Patent Application Laid-Open No. 2014-049557.

[0033] The electret 15 a and the electret 15 b are also collectively referred to as electrets 15 .

[0034] In addition, electrodes formed with the electret 15 like the first electret electrode 11 a and the second electret electrode 11 b are also collectively referred to as electret electrodes 11 .

[0035] The intermediate electrode 12 is held by the support frame 13 via a holding portion 14 that is elastically deformable, such as a spring. Figure 1 The X direction shown in the figure ( Figure 1 When the intermediate electrode 12 vibrates in the X direction (in the vertical direction), the intermediate electrode 12 vibrates relative to the first electret electrode 11a and the second electret electrode 11b in the X direction due to the elastic deformation of the holding portion 14. Specifically, a relative vibration between the electrodes is generated along with the vibration of the intermediate electrode 12, so that the electrostatic capacitance (the area facing each other between the electrodes) between the intermediate electrode 12 and the first electret electrode 11a and the electrostatic capacitance (the area facing each other between the electrodes) between the intermediate electrode 12 and the second electret electrode 11b increase and decrease in opposite phases. In this way, since the electrostatic capacitance between the intermediate electrode 12 and the two electret electrodes 11 changes in opposite phases to each other, the power generation efficiency is better than that of an electrostatic capacitance type vibration power generation element in which a fixed comb-tooth electrode and a movable comb-tooth electrode that are engaged with each other are relatively moved.

[0036] The first electret electrode 11a and the second electret electrode 11b induce positive or negative charges, positive charges in the first embodiment, by the relative vibration of the intermediate electrode 12 and the electret electrode 11, and generate alternating current. The above-mentioned charges are output to the power supply device 40 provided outside the vibration power generation element 10 through the conductor wiring Wa connected to the first electret electrode 11a and the conductor wiring Wb connected to the second electret electrode 11b.

[0037] The power supply device 40 has a bridge-connected full-wave rectifier circuit including four diodes D1 to D4. The wiring Wa is connected to the anode of the diode D1 and the cathode of the diode D2, and the wiring Wb is connected to the anode of the diode D4 and the cathode of the diode D3.

[0038] The cathode of the diode D1 and the cathode of the diode D4 are connected to the first output terminal Vo1 of the power supply device 40 , and the anode of the diode D2 and the anode of the diode D3 are connected to the second output terminal Vo2 of the power supply device 40 and maintained at the ground potential.

[0039] One end of a charge injection wiring WI for injecting charges into the intermediate electrode 12 is connected to the intermediate electrode 12 .

[0040] The other end of the charge injection wiring WI is connected to one end of the resistor element RI. The other end of the resistor element RI is connected to the anode of the diode D2 and the anode of the diode D3 in the power supply device 40, that is, maintained at the ground potential.

[0041] The alternating current generated by converting the energy of vibration of the vibration power generating element 10 is output through the power supply device 40 as power having a ground potential at the second output terminal Vo2 and a positive potential at the first output terminal Vo1 .

[0042] Furthermore, the power supply device 40 may include, for example, a capacitor or a voltage converter including a chopper-type DC-DC converter.

[0043] Below, refer to Figure 2 The operating principle of the vibration power generating device 100 using the vibration power generating element 10 according to the embodiment will be described.

[0044] Figure 2 (a) to (c) show the states of charges induced in the electrodes at respective relative positions when the intermediate electrode 12 vibrates (moves) in the X direction relative to the first electret electrode 11 a and the second electret electrode 11 b .

[0045] Figure 2 (a) shows the state of charge when the intermediate electrode 12 is at the middle point of vibration (hereinafter also referred to as the neutral point).

[0046] Since the end portion on the +X side of the intermediate electrode 12 faces the negative charge 16 a of the electret 15 a formed on the surface of the first electret electrode 11 a , a positive charge 17 a is induced in this portion.

[0047] Since the end portion of the intermediate electrode 12 on the −X side faces the negative charge 16 b of the electret 15 b formed on the surface of the second electret electrode 11 b , a positive charge 17 b is induced in this portion.

[0048] On the other hand, in the portion of the first electret electrode 11 a that is not opposed to the intermediate electrode 12 , negative charges 16 a generated by the electret 15 a are induced, and positive charges 18 a are induced inside the first electret electrode 11 a .

[0049] The portion of the second electret electrode 11 b that is not opposed to the intermediate electrode 12 is induced by the negative charge 16 b generated by the electret 15 b , and positive charge 18 b is induced inside the second electret electrode 11 b .

[0050] The above description Figure 2(a) shows a case where no electromotive force is generated between the first electret electrode 11a and the second electret electrode 11b and no charge transfer occurs. Figure 2 The position of the intermediate electrode 12 in (a) is called a neutral point, and the vibration power generating element 10 is said to be in a neutral state.

[0051] Figure 2 (b) with Figure 2 (a) shows a state where the intermediate electrode 12 is relatively moved toward the +X side.

[0052] exist Figure 2 (b) Figure 2 Compared with the state of (a), the area of ​​the portion of the surface of the first electret electrode 11a facing the intermediate electrode 12 increases. Therefore, the positive charge 17a of the intermediate electrode 12 induced by the negative charge 16a of the electret 15a increases. As a result, Figure 2 A part of the positive charge 18a induced inside the first electret electrode 11a in the state (a) is referred to as a residual charge 19a.

[0053] On the other hand, Figure 2 (b) Figure 2 Compared with the state of (a), the area of ​​the portion of the surface of the second electret electrode 11b facing the intermediate electrode 12 is reduced. Therefore, the positive charges 17b of the intermediate electrode 12 induced by the negative charges 16b of the electret 15b are reduced. As a result, a charge deficiency portion 20b is generated inside the second electret electrode 11b, which is a portion where the positive charges that should be induced with respect to the negative charges 16b of the electret 15b are insufficient.

[0054] Therefore, in Figure 2 In the state (b), the first electret electrode 11a is positively charged and the second electret electrode 11b is negatively charged. By utilizing the electromotive force generated by the charging, the current I1 flows from the first electret electrode 11a to the second electret electrode 11b via the output circuit R, thereby generating electricity. Here, the resistor R provided between the first electret electrode 11a and the second electret electrode 11b represents Figure 1 A power supply device 40 is provided.

[0055] on the other hand, Figure 2 (c) with Figure 2 (a) shows the state where the intermediate electrode 12 moves relatively toward the -X side. Figure 2 (c) Figure 2Compared with the state of (a), excess charge 19b is generated inside the second electret electrode 11b, and a charge deficiency portion 20a is generated. This charge deficiency portion 20a is a portion where the positive charge to be induced inside the first electret electrode 11a is insufficient.

[0056] Therefore, in Figure 2 In the state (c), the first electret electrode 11a is negatively charged and the second electret electrode 11b is positively charged. The electromotive force generated by the charging causes a current I2 to flow from the second electret electrode 11b to the first electret electrode 11a, thereby generating electricity.

[0057] Furthermore, the intermediate electrode 12 may be held by the holding portion 14 in a state of being insulated from the first electret electrode 11 a , the second electret electrode 11 b , the support frame 13 , etc., and the holding portion 14 itself may be formed of an insulating material.

[0058] In addition, if the charge injection wiring WI is not used to inject the charge into the intermediate electrode 12, when the humidity of the environment in which the vibration power generating element 10 is installed is high, the charge that should be retained in the intermediate electrode 12 may be discharged via water vapor or ions in the atmosphere, or the charge that should be induced by the intermediate electrode 12 may be combined with ions in the gas and become neutral. In this specification, the case where the intermediate electrode 12 is discharged and becomes neutral as described above is collectively referred to as neutralization of the intermediate electrode 12.

[0059] Figure 3 1 is a diagram showing the operation of the vibration power generating element 10 when the intermediate electrode 12 is neutralized. Figure 2 same, Figure 3 (a) to (c) show the states of charges induced in the electrodes at respective relative positions when the intermediate electrode 12 vibrates (moves) in the X direction relative to the first electret electrode 11 a and the second electret electrode 11 b .

[0060] The following is based on Figure 3 The status is similar to the above Figure 2 The operation of the vibration power generating element 10 when the electric charge in the intermediate electrode 12 is discharged will be described based on the difference between the states shown.

[0061] Figure 3 (a) is Figure 2The figure corresponding to (a) shows the state of charge when the intermediate electrode 12 is at the middle point of vibration. In the state where the intermediate electrode 12 is discharged, no positive charge is induced in the portion 21a of the intermediate electrode 12 facing the first electret electrode 11a and the portion 21b facing the second electret electrode 11b. Therefore, positive charge 22a induced by the negative charge 16a of the electret 15a is generated inside the portion of the first electret electrode 11a facing the intermediate electrode 12. Positive charge 22b induced by the negative charge 16a of the electret 15b is also generated inside the portion of the second electret electrode 11b facing the intermediate electrode 12.

[0062] Figure 3 (b) is related to Figure 2 (b) The corresponding figure shows that the intermediate electrode 12 Figure 3 The position shown in (a) is relatively moved to the +X side.

[0063] Figure 3 (c) is related to Figure 2 (c) The corresponding figure shows that the intermediate electrode 12 Figure 3 The position shown in (a) is relatively moved toward the -X side.

[0064] and Figure 2 The situation shown is different. Figure 3 In the case of the intermediate electrode 12, there is no charge, so even if the intermediate electrode 12 Figure 3 (a) The state of Figure 3 (b) or Figure 3 The state of (c) is changed, and the states of the charges in the first electret electrode 11a, the second electret electrode 11b, and the intermediate electrode 12 do not change.

[0065] That is, Figure 3 As shown, when the intermediate electrode 12 is neutralized, even if the electret electrode 11 and the intermediate electrode 12 relatively move (vibrate), no excess charge or insufficient charge is generated in either the first electret electrode 11a or the second electret electrode 11b, and power generation cannot be performed.

[0066] Therefore, in the vibration power generating element 10 of the embodiment, in order to prevent the loss of charge from the intermediate electrode 12, a charge injection wiring WI and a resistor RI are used to inject charge from the power supply device 40 to the intermediate electrode 12. The charge injection wiring WI and the resistor RI can be interpreted as a charge injector 30.

[0067] In the vibration power generation element 10, due to the charge induction of the electret 15 of the electret electrode 11 facing the intermediate electrode 12, a charge having opposite characteristics to the charge of the electret 15 is injected into the intermediate electrode 12 from the power supply device 40 via the charge injector 30. In the case where a negative charge region is provided on the surface of the electret electrodes 11a and 11b, a positive charge is injected into the intermediate electrode 12. By injecting the positive charge from the charge injector 30, the vibration power generation element 10 can maintain the charge of the intermediate electrode 12 for a long time, that is, can maintain high power generation efficiency for a long time. Among the electret electrode with positive charge and the intermediate electrode with negative charge, the negative charge is injected into the intermediate electrode.

[0068] In addition, the location where the charge injector 30 is connected is not limited to the anode of the diode D2 and the anode of the diode D3 in the power supply device 40 described above, and other locations in the power supply device 40 may be used. However, it is preferable that the charge injector 30 is connected to a portion in the power supply device 40 that is connected with a low resistance to the wiring Wa connected to the first electret electrode 11a or the wiring Wb connected to the second electret electrode 11b. Therefore, the charge injector 30 only needs to be connected to a portion in the power supply device 40 that is connected with a certain resistance to the wiring Wa and the wiring Wb, respectively.

[0069] Furthermore, the resistor element RI constituting the charge injector 30 can also be omitted.

[0070] (Variant 1)

[0071] Figure 4 This is a diagram showing a vibration power generating element 10 a according to Modification 1. The same reference numerals are used for the common parts with the vibration power generating element 10 according to the above-described embodiment, and the description thereof will be omitted.

[0072] The vibration power generating element 10 a of Modification 1 includes a plurality of electret electrodes 11 arranged in parallel, and an intermediate electrode 12 is arranged between the plurality of electret electrodes 11 .

[0073] Each intermediate electrode 12 is held by an elastically deformable holding portion 14 such as a spring so as to be vibrating in the X direction in the figure relative to the support frame 13. Also, as in the above-described embodiment, one end of a charge injection wiring WI (a part of the charge injector 30 of the above-described embodiment) for injecting charges into the intermediate electrode 12 is connected to each intermediate electrode 12.

[0074] In each of the first electret electrode 11 a and the second electret electrode 11 b of the electret electrodes 11 , the electret 15 is formed on the side facing the intermediate electrode 12 similarly to the above-described embodiment.

[0075] Since the third electret electrode 11 a 1 and the fourth electret electrode 11 b 1 face the intermediate electrode 12 on both sides of the surfaces, electrets 15 are formed on both sides of the surfaces.

[0076] The first electret electrode 11 a and the third electret electrode 11 a 1 are connected to the wiring Wa, while the second electret electrode 11 b and the fourth electret electrode 11 b 1 are connected to the wiring Wb.

[0077] Furthermore, the first electret electrode 11 a and the third electret electrode 11 a 1 are arranged to be offset in the +X direction with respect to the second electret electrode 11 b and the fourth electret electrode 11 b 1 .

[0078] When the intermediate electrode 12 vibrates relative to the electret electrode 11 in the X direction, charges are induced in the first electret electrode 11a and the third electret electrode 11a1 and the second electret electrode 11b and the fourth electret electrode 11b1, respectively, similarly to the above-mentioned embodiment, thereby generating electric power.

[0079] In Modification 1, since the charge injection wiring WI (one end of the charge injector 30 ) for injecting charges is connected to the intermediate electrode 12 , the vibration power generating element 10 a can prevent the intermediate electrode 12 from being neutralized and maintain high power generation efficiency for a long period of time.

[0080] (Variant 2)

[0081] Figure 5 This is a diagram showing a vibration power generating element 10 b according to Modification 2. The same reference numerals are used for the common parts with the vibration power generating element 10 according to the above-described embodiment, and the description thereof will be omitted.

[0082] In the vibration power generating element 10b of the modification 2, the plurality of electret electrodes 11 are arranged to be fixed to the inner side surface of the support frame 13a. In addition, the plurality of intermediate electrodes 12a are held by the conductive support body 25, and the support body 25 is held by the insulating holding portion 14a which is elastically deformable such as a spring so as to be able to vibrate in the X direction in the figure relative to the support frame 13a. The charge injection wiring WI is connected to the conductive support body 25, so that the charge is injected from the charge injection wiring WI to the plurality of intermediate electrodes 12a via the conductive support body 25.

[0083] Each of the plurality of intermediate electrodes 12a is arranged so as to face the first electret electrode 11a2 and the second electret electrode 11b2 with substantially equal areas at the center position (neutral position) of the vibration in the X direction of the support 25. Therefore, when the support 25 holding the intermediate electrodes 12a vibrates in the X direction, the area of ​​the facing portion of each intermediate electrode 12a and the first electret electrode 11a2 and the second electret electrode 11b2 changes. That is, the area of ​​the facing portion increases and decreases in opposite directions, in other words, in opposite phases.

[0084] Thus, as in the above-mentioned embodiment, charges are induced in the first electret electrode 11a2 and the second electret electrode 11b2 to generate electricity. The first electret electrodes 11a2 are connected to wirings Wa, and the second electret electrodes 11b2 are connected to wirings Wb, so that the induced charges can be taken out by wirings Wa and Wb. Furthermore, since charges are injected into the intermediate electrode 12a by the charge injection wiring WI to prevent neutralization, the vibration power generation element 10b can maintain high power generation efficiency for a long time.

[0085] (Variant 3)

[0086] Figure 6 It is a diagram showing a vibration power generating element 10 c according to Modification 3. Figure 6 (a) is a top view of the vibration power generating element 10c. Figure 6 (b) indicates observation from the -Y direction Figure 6 (a) is a cross-sectional view of the BB section. The same reference numerals are used for the common parts with the vibration power generating element 10 of the above-described embodiment, and the description thereof will be omitted.

[0087] The vibration power generating element 10 c of Modification 3 is similar to the vibration power generating element 10 a of Modification 1 described above, and includes a plurality of electret electrodes 11 , and intermediate electrodes 12 b 1 to 12 b 3 are disposed between the plurality of electret electrodes 11 .

[0088] Each intermediate electrode 12b1 to 12b3 is held so as to be able to swing in the X direction in the figure with the holding portion 14b as the center substantially via an elastically deformable holding portion 14b such as a metal thin plate. The charge injection wiring WI is connected to the holding portion 14b, so that the charge is injected into the intermediate electrodes 12b1 to 12b3 via the conductive holding portion 14b by the charge injection wiring WI. An insulating member is provided between the holding portion 14b and the support frame 13.

[0089] On the other hand, regarding each electret electrode 11 , the first electret electrode 11 a 3 and the third electret electrode 11 a 4 connected to the wiring Wa are arranged to be offset in the −X direction with respect to the second electret electrode 11 b 3 and the fourth electret electrode 11 b 4 connected to the wiring Wb. Figure 6 (b) indicates this situation.

[0090] Figure 6 (b) Observed from -Y direction Figure 6 The cross-sectional view of the BB section in (a) shows the intermediate electrode 12b2 swinging upward (in the +X direction) in the figure, and the fourth electret electrode 11b4 located on the inner side (in the +Y direction) of the intermediate electrode 12b2. In addition, the third electret electrode 11a4 indicated by the dotted line is located at a position higher than that of the intermediate electrode 12b2. Figure 6 The B-B section in (a) is close to -Y and is not shown here for easy understanding. Figure 6 As shown in (b).

[0091] like Figure 6 As shown in (b), when the intermediate electrode 12b2 oscillates (vibrates) in the X direction by the vibration in the X direction, the area of ​​the opposing portion of the intermediate electrode 12b2 and the third electret electrode 11a4 and the fourth electret electrode 11b4 changes. That is, the area of ​​the opposing portion increases and decreases in opposite directions, in other words, in opposite phases.

[0092] Thus, similarly to the above-described embodiment, electric charges are induced in the third electret electrode 11a4 and the fourth electret electrode 11b4, and power generation is performed. The same is true for the electret electrodes 11 facing the other intermediate electrodes 12b1 and 12b3.

[0093] In addition, since charges are injected into the intermediate electrodes 12 b 1 to 12 b 3 by the charge injection wiring WI to prevent neutralization, the vibration power generating element 10 c can maintain high power generation efficiency for a long period of time.

[0094] (Variant 4)

[0095] Figure 7 It is a diagram showing a vibration power generating element 10d according to Modification 4. The same reference numerals are used for the common parts with the vibration power generating element 10 according to the above-mentioned embodiment, and the description thereof is omitted.

[0096] In the vibration power generating element 10d of variant example 4, between the first electret electrode 11a fixed to the support frame 13 and connected to the wiring Wa and the second electret electrode 11b fixed to the support frame 13 and connected to the wiring Wb, the first intermediate electrode 12c1, the fifth electret electrode 11c, and the second intermediate electrode 12c2 are arranged in sequence from the first electret electrode 11a side.

[0097] The first intermediate electrode 12c1 and the second intermediate electrode 12c2 are each connected to an elastically deformable holding portion 14 such as a spring. One end of each holding portion 14 is connected to the support frame 13, and the other end is connected to the support frame extension portion 21 fixed to the support frame 13. Therefore, the first intermediate electrode 12c1 and the second intermediate electrode 12c2 are held relative to the support frame 13 so as to be vibrable in the X direction in the figure.

[0098] Furthermore, the charge injection lines WI are connected to the first intermediate electrode 12c1 and the second intermediate electrode 12c2, respectively.

[0099] The fifth electret electrode 11c is fixed to the support frame 13 by a holding mechanism (not shown). The fifth electret electrode 11c is not provided with wiring Wa, wiring Wb and other output lines, and the fifth electret electrode 11c is electrically floating. The two surfaces of the fifth electret electrode 11c are respectively opposed to the first intermediate electrode 12c1 and the second intermediate electrode 12c2, so electrets 15c are formed on the two surfaces.

[0100] In the vibration power generating element 10d of the modification 4, power generation is also performed based on the above principle by the first intermediate electrode 12c1 and the second intermediate electrode 12c2 vibrating relative to each electret electrode 11 in the X direction. Furthermore, charges are injected into the first intermediate electrode 12c1 and the second intermediate electrode 12c2 by the charge injection wiring WI to prevent neutralization, so that the vibration power generating element 10d can maintain high power generation efficiency for a long time.

[0101] (Variant 5)

[0102] Figure 8 It is a diagram showing a vibration power generating element 10 e according to Modification 5 and a vibration power generating device 100 b including the vibration power generating element 10 e .

[0103] Since most of the structures of the vibration power generating element 10 e and the vibration power generating device 100 b of the modification 5 are the same as those of the vibration power generating element 10 and the vibration power generating device 100 of the above-mentioned embodiment, the same reference numerals are given to the common parts and the description thereof is omitted.

[0104] The vibration power generating element 10e of the modification 5 is provided with a charge injection wiring WI and a switch element TI such as a MOSFET as a charge injector 30b. A voltage conversion circuit VC is provided in the power supply device 40a, and the output voltage of the voltage conversion circuit VC is monitored by a voltage detection integrated circuit VD. When the output voltage of the voltage conversion circuit VC is lower than a predetermined value, the voltage detection integrated circuit VD sends a control signal to the switch element TI, and the switch element TI is turned on according to the control signal. Thus, charge is injected from the power supply device 40a to the intermediate electrode 12.

[0105] When the output voltage of the voltage conversion circuit VC is higher than a predetermined value, the voltage detection integrated circuit VD does not send a control signal to the switching element TI, and the switching element TI is turned off.

[0106] In the vibration power generating element 10 e of the fifth modification, the injection of charges into the intermediate electrode 12 can be controlled by switching the switching element TI on or off.

[0107] In Modification 5, a signal for monitoring the voltage in the power supply device 40a is used as a control signal for the control unit, i.e., the switching element TI. Therefore, when the voltage in the power supply device 40a decreases, i.e., when the power generation efficiency of the vibration power generation element 10e decreases, the charge is injected into the intermediate electrode 12, so that the power generation efficiency of the vibration power generation element 10e can be restored.

[0108] Furthermore, the control signal for the switching element TI is not limited to the signal for monitoring the voltage in the power supply device 40a. For example, a trigger signal generated by a timing circuit at predetermined intervals may be used as the control signal for the switching element TI.

[0109] (Variant 6)

[0110] Fig. 9 It is a diagram showing a vibration power generating element 10f according to Modification Example 6.

[0111] Since most of the structure of the vibration power generating element 10 f according to the modification example 6 is the same as that of the vibration power generating element 10 according to the above-mentioned embodiment, the same reference numerals are given to the common parts and the description thereof is omitted.

[0112] The vibration power generating element 10f of the modification example 6 has: a charge injection wiring WI having one end connected to the intermediate electrode 12; a resistor element RI1 having one end connected to the other end of the charge injection wiring WI and the other end connected to the wiring Wa; and a resistor element RI2 having one end connected to the other end of the charge injection wiring WI and the other end connected to the wiring Wb. The charge injection wiring WI, the resistor element RI1, and the resistor element RI2 constitute a charge injector 30c.

[0113] Furthermore, the resistance element RI1 and the resistance element RI2 are configured to have a resistance value sufficiently larger than the resistance generated by the load of the power supply device 40 connected to the vibration power generating element 10 f .

[0114] In the vibration power generating element 10f of Modification 6, charges are injected from the first electret electrode 11a via the resistor element RI1 and from the second electret electrode 11b via the resistor element RI2 into the intermediate electrode 12. Therefore, it is possible to prevent the charges in the intermediate electrode 12 from being lost due to discharge, and it is possible to maintain the high power generating efficiency of the vibration power generating element 10f for a long time.

[0115] The connection method of the resistor elements RI1 and RI2 is not limited to the above-described method. For example, the resistor elements RI1 and RI2 may be directly connected to the first electret electrode 11a and the second electret electrode 11b respectively without passing through the wiring Wa and the wiring Wb.

[0116] Alternatively, a configuration may be adopted in which one of the resistor elements RI1 and RI2 is omitted and charges are injected into the intermediate electrode 12 from one of the first electret electrode 11 a and the second electret electrode 11 b .

[0117] In addition, the resistors RI1 and RI2 of the vibration power generating element 10f can be replaced by the switch element TI of the above-mentioned modification 5, or the resistors RI1 and RI2 and the switch element TI can be arranged in series. Thus, the following structure can be made: whenever the voltage for power generation decreases, charge is injected from the electret electrode 11 to the intermediate electrode 12.

[0118] Furthermore, the charge injectors 30 , 30 a , 30 b included in the above-mentioned Modifications 5 and 6 can also be applied to the vibration power generating elements 10 , 10 a to 10 d of the above-mentioned Modifications 1 to 4 to inject charges into the intermediate electrodes 12 , 12 a , 12 b .

[0119] In the above-described embodiment and each modified example, the electret electrode 11 is fixed to the support frame 13, and the intermediate electrode 12 is configured to vibrate or swing relative to the support frame 13. However, the present invention is not limited to this configuration, and the intermediate electrode 12 may be fixed to the support frame 13, and the electret electrode 11 may be configured to vibrate or swing relative to the support frame 13.

[0120] In the embodiment and each modified example, the direction of the relative vibration between the intermediate electrode 12 and the electret electrode 11 is set to be a direction parallel to the surface of the electret electrode 11 facing the intermediate electrode 12 (X direction), but the vibration direction is not limited to this direction. For example, by vibrating in a direction perpendicular to the facing surface, the facing distance between the electret electrode 11 and the intermediate electrode 12 is changed, and the electrostatic capacitance of the capacitor formed by the two electrodes is changed, so that charge can be induced to generate electricity.

[0121] However, by setting the direction of relative vibration to a direction parallel to the surface of the electret electrode 11 facing the intermediate electrode 12 , the power generation efficiency can be further improved.

[0122] (Effects of the Embodiment and Each Modification Example)

[0123] (1) The vibration power generating element 10, 10a to 10f of the embodiment and each modified example described above is a vibration power generating element that outputs AC power from an output line by utilizing vibration from the outside, and includes: an intermediate electrode 12 that is not connected to the output line; a plurality of electret electrodes 11 that are arranged to face the intermediate electrode 12 and have an electret 15 on at least a portion of the surface facing the intermediate electrode 12; a holding portion 14 that holds the intermediate electrode 12 and the plurality of electret electrodes 11 so as to be able to vibrate relative to each other; and a charge injector 30 that injects charges of opposite characteristics to those of the electrets 15 formed on the surfaces of the plurality of electret electrodes 11 into the intermediate electrode 12. In the embodiment, the intermediate electrode 12 vibrates relative to the plurality of electret electrodes 11 by the vibration of the intermediate electrode 12.

[0124] According to this structure, the neutralization of the intermediate electrode 12 can be prevented, and the vibration energy of the environment where the vibration power generating elements 10 and 10a to 10f are installed can be efficiently converted into electric energy for a long period of time. In other words, the power generation efficiency can be improved.

[0125] (2) Furthermore, by setting the direction of relative vibration between the electret electrode 11 and the intermediate electrode 12 to a direction parallel to the surface of the plurality of electret electrodes 11 facing the intermediate electrode 12, the power generation efficiency can be further improved, and even a vibration power generation element of the same size as in the past can generate greater power.

[0126] (3) In (2), if the intermediate electrode 12 moves in a first direction relative to the plurality of electret electrodes 11, the area of ​​the opposing portion between one of the plurality of electret electrodes 11 and the intermediate electrode 12 increases, and the area of ​​the opposing portion between another of the plurality of electret electrodes 11 and the intermediate electrode 12 decreases. If the intermediate electrode 12 moves in a second direction different from the first direction, the area of ​​the opposing portion increases or decreases in the opposite direction to the movement in the first direction. By making the above structure, the power generation efficiency can be further improved.

[0127] (4) In (1) to (3), the charge injector 30 may connect a part of a circuit (power supply device 40 ) that receives power from the vibration power generating elements 10 and 10 a to 10 f to the intermediate electrode 12 .

[0128] (5) In (1) to (3), the charge injector 30 may include resistor elements RI1 and RI2 , one end of the charge injector 30 is connected to the intermediate electrode 12 , and the other end is connected to at least one of the plurality of electret electrodes 11 .

[0129] (6) In the above, a control unit (switching element TI) may be provided to control the charge injected by the charge injector 30 into the intermediate electrode 12. With this configuration, the charge injector 30 can inject charge into the intermediate electrode 12 only when necessary.

[0130] (7) The vibration power generating devices 100, 100a, 100b described above include the vibration power generating elements 10, 10a to 10f of the above embodiment and each modified example and the power supply device 40, 40a. According to this structure, the energy of the vibration of the environment in which the vibration power generating devices 100, 100a, 100b are installed can be efficiently converted into electrical energy. In other words, the power generation efficiency can be improved.

[0131] In the above description, various embodiments and variations are described, but the present invention is not limited to these contents. In addition, each embodiment and variation can be applied separately or in combination. Other modes considered within the scope of the technical idea of ​​the present invention are also included in the scope of the present invention.

[0132] The disclosures of the following priority basic applications are incorporated herein by reference.

[0133] Japanese Patent Application No. 90196, 2018 (filed on May 8, 2018)

[0134] Explanation of symbols

[0135] 100, 100a, 100b—vibration power generation device, 10, 10a~10f—vibration power generation element, 11—electret electrode, 11a—first electret electrode, 11b—second electret electrode, 12, 12a—intermediate electrode, 13, 13a—support frame, 14, 14a—holding part, 15, 15a, 15b—electret, 30, 30a~30c—charge injector, 40—power supply circuit, D1~D4—diodes, VC—voltage conversion circuit, VD—integrated circuit for voltage detection.

Claims

1. A vibration power generating element that uses vibration from the outside to output alternating current from an output line, The vibration power generating element is characterized by comprising: an intermediate electrode, which is not connected to the output line; a plurality of electret electrodes disposed opposite to the intermediate electrode and having an electret on at least a portion of a surface of a surface opposite to the intermediate electrode; a holding portion that holds the intermediate electrode and the plurality of electret electrodes so as to be able to vibrate freely relative to each other; and a charge injector for injecting charges of opposite characteristics to the electrets formed on the surfaces of the plurality of electret electrodes into the intermediate electrode via a charge injection wiring line, the charge injection wiring line being different from the output line, The charge injector connects a part of a circuit that receives power supply from the vibration power generating element to the intermediate electrode.

2. The vibration power generating element according to claim 1, characterized in that: The direction of the relative vibration is a direction parallel to the surfaces of the plurality of electret electrodes that face the intermediate electrode.

3. The vibration power generating element according to claim 2, characterized in that: If the intermediate electrode moves relative to the plurality of electret electrodes in a first direction through the relative vibration, the area of ​​the opposing portion between one of the plurality of electret electrodes and the intermediate electrode increases, while the area of ​​the opposing portion between another of the plurality of electret electrodes and the intermediate electrode decreases. If the intermediate electrode moves in a second direction different from the first direction, the area of ​​the opposing portion increases or decreases in the opposite direction to the movement in the first direction.

4. The vibration power generating element according to any one of claims 1 to 3, characterized in that: The charge injector includes a resistor element, one end of the charge injector is connected to the intermediate electrode, and the other end of the charge injector is connected to at least one of the plurality of electret electrodes.

5. The vibration power generating element according to claim 1, characterized in that: A control component is provided, which controls the charge injection from the charge injector to the intermediate electrode.

6. The vibration power generating element according to claim 4, characterized in that: A control component is provided, which controls the charge injection from the charge injector to the intermediate electrode.

7. A vibration power generation device, characterized in that: have: The vibration power generation element according to any one of claims 1 to 6; and Power supply unit.

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