Vibration power generation device

Abstract

A vibration power generation device includes: a first electrode; a second electrode, which is opposite to the first electrode; a holding portion, which holds at least one of the first electrode and the second electrode in a relatively movable manner; a half-wave rectifier, which is electrically connected to the first electrode and the second electrode, so that the current flowing from the first electrode to the second electrode flows through the output portion and cuts off the current flowing from the second electrode to the first electrode; and a second rectifying element, which is electrically connected to the first electrode and the second electrode, so that the current flowing from the second electrode to the first electrode flows and cuts off the current flowing from the first electrode to the second electrode, wherein the first electrode has a positively charged electret on the surface of the surface opposite to the second electrode, or the second electrode has a negatively charged electret on the surface of the surface opposite to the first electrode.

Description

Technical Field

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

[0002] As one of the energy harvesting technologies for harvesting energy from environmental vibrations, there is a known method of generating electricity from environmental vibrations using a vibration power generation element that is a MEMS (Microelectromechanical Systems) vibration element. The vibration power generation element itself is an element that has a piezoelectric element or an electrostatic capacitance type element, and when it is vibrated at the frequency of the environmental vibration, it generates an AC power equal to the frequency. Therefore, a vibration power generation device that combines a vibration power generation element and a power supply circuit is proposed, and the power supply circuit converts the AC power generated by the vibration power generation element into a DC or AC voltage suitable for use (for example, refer to Patent Document 1). In Patent Document 1, in the rectification (conversion from AC to DC) of the AC power generated by the electrostatic capacitance type vibration power generation element, a general two-phase full-wave rectifier circuit is used as a rectifier circuit.

[0003] Prior art documents

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-172523. 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 device that can efficiently convert environmental vibration into electrical energy is required.

[0008] [Methods used to solve the problem]

[0009] The first method relates to a vibration power generation device, comprising: a first electrode; a second electrode, opposite to the first electrode; a holding portion, holding at least one of the first electrode and the second electrode in a relatively movable manner; a half-wave rectifier, comprising a first rectifying element and an output portion, electrically connected to the first electrode and the second electrode, so that a current flowing from the first electrode to the second electrode flows through the output portion, and a current flowing from the second electrode to the first electrode is cut off; and a second rectifying element, electrically connected to the first electrode and the second electrode, so that a current flowing from the second electrode to the first electrode flows, and a current flowing from the first electrode to the second electrode is cut off, the first electrode having a positively charged electret on the surface of the surface opposite to the second electrode, or the second electrode having a negatively charged electret on the surface of the surface opposite to the first electrode.

[0010] The vibration power generating device involved in the second embodiment is based on the vibration power generating device involved in the first embodiment, and preferably has two of the first electrodes, the second electrode, the first rectifying element and the second rectifying element respectively, and one of the two first electrodes or the two second electrodes is electrically connected, and one end of each of the two second rectifying elements is electrically connected, and the other of the two first electrodes or the two second electrodes different from the one is electrically connected to the other end different from the one end of each of the two second rectifying elements, and is electrically connected to one end of each of the two first rectifying elements.

[0011] The vibration power generating device involved in the third embodiment is preferably based on the vibration power generating device involved in the second embodiment, wherein the holding portion comprises: a first holding portion for holding the two first electrodes as a whole; a second holding portion for holding the two second electrodes as a whole; and a relative moving portion for allowing the two first electrodes and the two second electrodes to move freely relative to each other.

[0012] A vibration power generator according to a fourth aspect is preferably the vibration power generator according to any one of the first to third aspects, wherein the output unit includes a capacitor and a voltage conversion circuit arranged in parallel with the capacitor.

[0013] A vibration power generating device according to a fifth aspect is the vibration power generating device according to any one of the first to fourth aspects, wherein preferably at least one of the first rectifying element and the second rectifying element is a diode.

[0014] [Effects of the Invention]

[0015] According to the present invention, the energy of environmental vibration can be efficiently converted into electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram showing a schematic structure of the vibration power generating device 100 according to the first embodiment of the present invention.

[0017] Figure 2 This is a diagram schematically illustrating the operating principle of the vibration power generator according to the first embodiment.

[0018] Figure 3 (a) is a diagram showing the relationship between the power generation output and time of the vibration power generator according to the first embodiment, Figure 3 (b) is a graph showing the relationship between the power generation output and time of a conventional vibration power generator.

[0019] Figure 4 1 is a schematic diagram showing a schematic structure of a vibration power generating device 100 a according to Modification 1.

[0020] Figure 5It is a schematic diagram showing a schematic structure of a vibration power generating device 100 b according to a second embodiment of the present invention.

[0021] Figure 6 It is a schematic diagram showing a schematic structure of a vibration power generating device 100 c according to Modification 2. DETAILED DESCRIPTION

[0022] (First Embodiment)

[0023] Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. Figure 1 1 is a schematic diagram showing a schematic structure of a vibration power generating device according to a first embodiment of the present invention. The vibration power generating device 100 includes a vibration power generating element 10 that generates AC power by environmental vibration, and a half-wave rectifier 40 that extracts the generated AC power as a power source.

[0024] The electrostatic capacitance type vibration power generating element 10 has a first electrode 11 and a second electrode 12. The first electrode 11 is a movable electrode as an example, and the second electrode 12 is a fixed electrode as an example. The first electrode 11 is a comb-tooth electrode having two comb-tooth portions 21 as an example, and the second electrode 12 is a comb-tooth electrode having three comb-tooth portions 22 as an example.

[0025] The comb-tooth portion 21 of the first electrode 11 and the comb-tooth portion 22 of the second electrode 12 have a predetermined thickness in the Z direction of the figure, and the meshing portions thereof face each other.

[0026] The first electrode 11 and the second electrode 12 can be manufactured as a MEMS structure using silicon as a base material, for example.

[0027] An electret having negative charge is formed by subjecting a region 25 of the surface of the comb-tooth portion 22 of the second electrode 12 that faces the comb-tooth portion 21 of the first electrode 11 to a known charging process (for example, the charging process described in Japanese Patent Application Laid-Open No. 2014-049557).

[0028] The comb-teeth 22 of the second electrode 12 are semi-permanently charged by electretization. As a result, positive induced charges opposite to the electret electrode characteristics are induced on the comb-teeth 21 of the first electrode 11 facing the electret electrode.

[0029] In addition, when the surface of the fixed electrode or the movable electrode is not silicon, a film of polycrystalline silicon or amorphous silicon may be formed on the surface before the charging process is performed.

[0030] The second electrode 12 is fixedly held by an insulating support frame 13 .

[0031] On the other hand, the first electrode 11 is held by the holding portion 14 (electrode holding portion 14a, connecting portion 14b, fixing portion 14c) so as to vibrate in the vertical direction (X direction) in the figure relative to the support frame 13. The holding portion 14 includes the electrode holding portion 14a that holds the first electrode 11, the fixing portion 14c fixed to the support frame 13, and the connecting portion 14b having flexibility that connects the electrode holding portion 14a and the fixing portion 14c.

[0032] The connecting portion 14b is Figure 1 A sheet made of a flexible material such as metal, which is thin in the X direction and thick in the Z direction. When vibration is applied to the support frame 13 from the outside, the two connecting parts 14b provided on the left and right of the electrode holding part 14a in the figure are bent, so that the electrode holding part 14a vibrates in the X direction relative to the support frame 13. As a result, the first electrode 11 held on the electrode holding part 14a vibrates in the X direction relative to the second electrode 12 fixed to the support frame 13.

[0033] As the first electrode 11 and the second electrode 12 vibrate in the X direction, the area of ​​the surface where the comb-teeth portion 21 of the first electrode 11 and the comb-teeth portion 22 of the second electrode 12 face each other increases or decreases. As a result, the area of ​​the portion where the first electrode 11 and the second electrode 12 face each other changes, the induced charge of the electret also changes, and the potential difference between the first electrode 11 and the second electrode 12 changes to generate an electromotive force, thereby generating electricity in the vibration power generation element 10.

[0034] In this specification, the conductive connection between an electric component and another electric component via a wiring composed of a conductor such as a metal or a semiconductor is referred to as electrical connection.

[0035] As will be described later, the vibration power generating element 10 converts vibration energy in the environment in which the vibration power generating device 100 is installed into electrical energy, thereby generating AC power.

[0036] The cathode of the diode D1 as the first rectifying element and the anode of the diode D2 as the second rectifying element are electrically connected to the second electrode 12. On the other hand, the cathode of the diode D2 is electrically connected to the first electrode 11.

[0037] Furthermore, the anode of the diode D1 as the first rectifying element is electrically connected to one end Vi1 of the input side of the output unit 30 including the capacitor C1 and the voltage converter VC, and the other end Vi2 of the input side of the output unit 30 is electrically connected to the cathode of the diode D2 and the first electrode 11. The potential of the first electrode 11 is the ground potential.

[0038] Thus, in the AC power generated by the vibration power generating element 10, when the first electrode 11 is at a positive potential and the second electrode 12 is at a negative potential, the diode D1 is forward biased, so that the current flowing from the first electrode 11 to the second electrode 12 charges the capacitor C1 through the diode D1. The charging voltage between the input terminals Vi1 and Vi2 of the output unit 30 is transformed by the voltage converter VC and output from one terminal Vo1 on the output side of the output unit 30 and the other terminal Vo2 on the output side to an external electronic device or charging device.

[0039] As the voltage converter VC, for example, a chopper-type DC-DC converter can be used.

[0040] When the first electrode 11 is at a positive potential and the second electrode 12 is at a negative potential, the diode D2 is reverse biased, so that the current does not flow through the diode D2 to the second electrode 12. That is, the current from the first electrode 11 to the second electrode 12 is blocked by the diode D2.

[0041] On the other hand, in the AC power generated by the vibration power generating element 10, when the first electrode 11 is at a negative potential and the second electrode 12 is at a positive potential, the diode D2 is forward biased, and current flows from the second electrode 12 to the first electrode 11. Since the direction of this current is the direction of the forward current of the diode D2, the resistance of the diode D2 is almost zero. When the first electrode 11 is at a negative potential and the second electrode 12 is at a positive potential, the diode D1 is reverse biased, so no current flows in the output unit 30.

[0042] The diode D1 and the output unit 30 constitute a half-wave rectifier 40 .

[0043] That is, in the first embodiment, it is characterized in that, among the AC power generated by the vibration power generating element 10, only the current flowing from the first electrode 11 to the second electrode 12 is taken out from the output portion 30, and the current flowing in the direction from the second electrode 12 to the first electrode 11 flows from the second electrode 12 to the first electrode 11 with almost no resistance (no load) through the diode D2 serving as a rectifying element.

[0044] According to this structure, the vibration power generation device 100 of the first embodiment can convert the energy of environmental vibration into electrical energy with higher efficiency than previous vibration power generation devices without weakening the electric field between the first electrode 11 and the second electrode 12 when the second electrode 12 that is electret is at a negative potential and the first electrode 11 is at a positive potential according to the principle to be described later.

[0045] Figure 2 1 is a diagram schematically showing the operating principle of the vibration power generating element 10. Figure 2 The reason why the vibration power generator 100 according to the first embodiment has high energy conversion efficiency will be described.

[0046] Figure 2 (a) to (c) indicate Figure 1 The comb-teeth portion 21 of the first electrode 11 and the comb-teeth portion 22 of the second electrode 12 are shown in FIG. Figure 1 A diagram showing the relative movement in the X direction. Figure 2 In the description, for simplicity, the comb-tooth portion 21 of the first electrode 11 is referred to as the first electrode 21 , and the comb-tooth portion 22 of the second electrode 12 is referred to as the second electrode 22 .

[0047] Figure 2 (a) is a diagram showing a state where the first electrode 21 and the second electrode 22 face each other at a predetermined portion. In a region 25 on the surface of the second electrode 22 facing the first electrode 21, an electret having negative charges 60 is formed.

[0048] The negative charge 60 induces positive charge 62 on the surface of the first electrode 21 facing the second electrode 22. On the other hand, the negative charge 60 of the region 25 induces positive charge 61 inside the second electrode 22 in the portion of the second electrode 22 not facing the first electrode 21.

[0049] The positive charges 62 induced by the first electrode 21 and the negative charges 60 generated by the electret on the surface of the second electrode 22 form an electric field E0 at the opposing portion of the first electrode 21 and the second electrode 22 .

[0050] Figure 2 The resistor R in (a) represents the power circuit and the load connected to the vibration power generating element 10 as a resistor. When the vibration power generating element 10 vibrates in the electric field E0, a voltage generated by a change in the electrostatic capacitance between the first electrode and the second electrode is applied to the resistor R. Figure 2 In the examples shown in (b) and (c), the output voltage of the vibration power generation element 10 is proportional to the vibration of the first electrode 21 and the second electrode 22. Figure 2 (a) shows an increase or decrease compared to the example shown.

[0051] Figure 2 (b) shows the first electrode 21 and the second electrode 22 from Figure 2 In the state shown in (a), the first electrode 21 and the second electrode 22 move relative to each other in the X direction, and the area ratio of the portion where the first electrode 21 and the second electrode 22 face each other is Figure 2 (a) shows the state of reduction.

[0052] exist Figure 2 (b) shows the state, and Figure 2 Compared to the state shown in (a), the positive charges 62 on the surface of the first electrode 21 induced by the negative charges 60 on the surface of the second electrode 22 decrease, and the positive charges 61 in the second electrode 22 induced by the negative charges 60 increase.

[0053] Therefore, due to the vibration of the electrode Figure 2 The state change of (a) is Figure 2 (b) When the Figure 2 In (a), part of the positive charge 62 induced in the first electrode 21 will become a current I1 and move from the first electrode 21 to the second electrode 22 via the resistor R (to be precise, electrons will move from the second electrode 22 to the first electrode 21). Therefore, the first electrode 21 has a positive potential relative to the second electrode 22.

[0054] However, since the movement of the charge is blocked by the resistance of the resistor R, a positive residual charge 64 remains on the first electrode 21, and a positive charge defect 63 is generated in a part of the second electrode 22 that faces the negative charge 60. Figure 2 Compared with the electric field E0 in the case of (a), the positive residual charges 64 and the positive charge defect portions 63 strengthen the electric field E1 of the opposing portion of the first electrode 21 and the second electrode 22 .

[0055] Figure 2 (c) shows the first electrode 21 and the second electrode 22 from Figure 2 In the state shown in (a), the first electrode 21 and the second electrode 22 move relative to each other in the X direction, and the area ratio of the portion where the first electrode 21 and the second electrode 22 face each other is Figure 2 (a) shows the situation where the state is enlarged.

[0056] exist Figure 2 (c) shows the state, and Figure 2 Compared with the state shown in (a), the positive charges 62 on the surface of the first electrode 21 induced by the negative charges 60 also increase, and the positive charges 61 in the second electrode 22 induced by the negative charges 60 decrease.

[0057] Therefore, due to the vibration of the electrode Figure 2 The state change of (a) is Figure 2 (c) When the Figure 2 Part of the positive charge 61 induced in the second electrode 22 in (a) will become a current I2 and move from the second electrode 22 to the first electrode 21 via the resistor R (more precisely, electrons will move from the first electrode 21 to the second electrode 22). Therefore, the first electrode 21 has a negative potential relative to the second electrode 22.

[0058] However, since the movement of the charge is blocked by the resistance of the resistor R, a positive residual charge 65 remains on the second electrode 22, and a positive charge defect 66 is generated in a portion of the first electrode 21 that faces the negative charge 60. Figure 2Compared with the electric field E0 in the case of (a), the positive residual charges 65 and the positive charge missing portions 66 weaken the electric field E2 at the opposing portion of the first electrode 21 and the second electrode 22 .

[0059] Thus, when the electric field E2 is weakened, the power generation efficiency of the vibration power generation element 10 is reduced. Therefore, when power is extracted from the vibration power generation element 10 in the state where the electric field E2 is weakened, the electrical damping is reduced, and the speed of conversion from mechanical energy to electrical energy is slowed down. Therefore, the energy (kinetic energy) of the environmental vibration accumulated in the second electrode 22 as the movable electrode cannot be effectively converted into electrical energy and is wasted.

[0060] In a first embodiment, if Figure 1 As shown in FIG. 1 , when the first electrode 11 is at a negative potential relative to the second electrode 12, current flows in the forward direction of the diode D2 as the second rectifying element. The forward resistance of the diode D2 is much smaller than the reverse resistance, so the circuit loss when the current flows from the second electrode 12 to the first electrode 11 is also small. As a result, when the Figure 2 In the circuit shown in the embodiment of the diode D2, as Figure 2 (a) to Figure 2 As shown in (c), the electric field E2d when the first electrode 21 and the second electrode 22 move relative to each other is Figure 2 (c) The electric field E2 in the circuit illustrated is large.

[0061] At first glance, it seems that the electric energy generated by causing the current to flow from the second electrode 12 to the first electrode 21 through the diode D2 is wasted. However, the resistance of the forward current of the diode D2 is substantially zero, and since the total amount of the current flowing is the amount of charge induced in the first electrode 11 and the second electrode 12, the upper limit is determined, so the amount of lost electric energy ΔEG2, that is, (resistance)×(current)×(current), is also small.

[0062] Figure 3 This is a diagram comparing the output of the vibration power generating device 100 according to the first embodiment and the output of a vibration power generating device using a conventional full-wave rectifying element.

[0063] Figure 3 (a) is a diagram showing the relationship between the power generation output (electric power) P1 and time t (horizontal axis) of the vibration power generator 100 according to the first embodiment, Figure 3 (b) is a graph showing the relationship between the power generation output (power) P2 and time t (horizontal axis) of a vibration power generator using a conventional full-wave rectifier element. The vertical axes of both graphs are output power P.

[0064] When a conventional full-wave rectifier such as a diode bridge is used, the sinusoidal power (voltage) induced between the first electrode and the second electrode of the vibration power generating element accompanying the relative vibration of the electrodes is reversed by the full-wave rectifier to positively invert the negative voltage, and outputs power P2 that is substantially equal to the absolute value of the sinusoidal wave. The time between adjacent peaks of the time variation of the power P2 is half the vibration period of the vibration power generating element.

[0065] on the other hand, Figure 3 The output P1 of the vibration power generating device 100 of the first embodiment shown in (a) is a state where, among the sinusoidal power (voltage) induced between the first electrode 11 and the second electrode 12, only the positive potential is induced in the first electrode 11 and the negative potential is induced in the second electrode 12. That is, since only the positive (or negative) part of the sinusoidal power (voltage) is output, the number of peaks is half compared to the output P2 when a conventional full-wave rectifier element is used.

[0066] However, in the case of a vibration power generation element, the energy of the vibration applied from the outside is equal to the sum of the mechanical energy lost as air resistance or friction and the electric energy generated by the vibration power generation element. Therefore, if the energy of the vibration applied from the outside and the mechanical energy lost are equal, the total amount of electric energy that can be taken out is constant regardless of the number of times (frequency) the electric energy is taken out.

[0067] Therefore, the magnitude (power) of a peak value of the output P1 of the vibration power generating device 100 of the first embodiment is larger than a peak value of the conventional output P2. Moreover, without considering the weakening of the electric field E2, the time average P10 of the output power of the vibration power generating device 100 of the first embodiment is equal to the time average P20 of the output power of the device using the conventional full-wave rectifier element.

[0068] Moreover, if the weakening of the electric field E2 mentioned above is taken into account, in a device using a conventional full-wave rectifier element, the weakening of the electric field E2 is inevitable and the power generation efficiency is reduced. Therefore, the time average P10 of the output power of the vibration power generation device 100 of the first embodiment exceeds the time average of the device using a conventional full-wave rectifier element.

[0069] As described above, in the power generation circuit provided with the diode D2, the electric field at the opposing portion of the first electrode 11 and the second electrode 12 becomes, for example, Figure 2 (c) shows an electric field E2d where the electric field E2 is high. The high electric field E2d increases the electrical damping. By increasing the electrical damping, the influence of the loss of mechanical damping is reduced, and the power generation efficiency of the vibration power generation element 10 can be improved.

[0070] Therefore, in the vibration power generating device 100 of the first embodiment, it is possible to convert the energy of the environmental vibration into electric energy with higher efficiency than in conventional devices.

[0071] In the first embodiment described above, the first electrode 11 is used as a movable electrode and the second electrode 12 is used as a fixed electrode, but the present invention is not limited to this structure. That is, the first electrode 11 may be used as a fixed electrode and the second electrode 12 may be used as a movable electrode.

[0072] In the half-wave rectifier 40 , the diode D1 is arranged on the second electrode 12 side and the output unit 30 is arranged on the first electrode 11 side. However, conversely, the output unit 30 may be arranged on the second electrode 12 side and the diode D1 may be arranged on the first electrode 11 side.

[0073] The operation of the vibration power generating device 100 according to the first embodiment is summarized as follows.

[0074] In the vibration power generating device of the first embodiment, the half-wave rectifier 40 includes a diode (first rectifying element) D1 and a DC-DC converter (output section) 30, an electret with negative charge 60 is provided on the second electrode 12, and no electret is provided on the first electrode 11. The diode D1 is arranged between the first electrode 11 and the second electrode 12 in a direction in which it is forward-biased by a current flowing from the first electrode 11 without the electret to the second electrode 12 with the electret with negative charge 60. The diode D2 is arranged in parallel with the diode D1 between the first electrode 11 and the second electrode 12 in a direction in which it is forward-biased by a current flowing from the second electrode 12 to the first electrode 11.

[0075] According to the change of the opposing area of ​​the first electrode 11 and the second electrode 12, the positive charge 62 of the first electrode 11 induced by the negative charge 60 of the electret of the opposing second electrode 12 decreases, and the positive charge 61 of the second electrode 12 increases. Figure 2 As shown in (b), the current I1 flows from the first electrode 11 to the second electrode 12 along the forward direction of the diode D1 to charge the capacitor C.

[0076] On the other hand, according to the change in the opposing area of ​​the first electrode 11 and the second electrode 12, the positive charge 62 of the first electrode 11 induced by the negative charge 60 of the electret of the second electrode 12 increases, and the positive charge 61 of the second electrode 12 decreases. Figure 2As shown in (c), the current I2 flows from the second electrode 12 to the first electrode 11 along the forward direction of the diode D2. However, since the diode D2 is not connected to the output unit 30, the current I2 at this time is not used for output, but the positive charge moves from the second electrode 12 to the first electrode 11. Therefore, it is possible to form an electric field E2d higher than the electric field E2 generated by the circuit structure without the diode D2 but only by the diode D1, and the conversion efficiency of the vibration power generation device can be improved.

[0077] (Variant 1)

[0078] Reference Figure 4 , a vibration power generating device 100a according to Modification 1 will be described. Note that the same components as those of the first embodiment are denoted by the same reference numerals and description thereof will be omitted.

[0079] The vibration power generating element 10a included in the vibration power generating device 100a of Modification 1 is different from the first embodiment in that the first electrode 11 having no electret is a fixed electrode and the second electrode 12 having a negatively charged electret is a movable electrode.

[0080] The first electrode 11 as a fixed electrode is fixedly held by the insulating support frame 13 .

[0081] On the other hand, the second electrode 12 as a movable electrode is held by the holding portion 14 so as to vibrate in the vertical direction (X direction) in the figure relative to the support frame 13. In the comb-tooth portion 22 of the second electrode 12, an electret having a negative charge is formed in a region 25 on the surface of the surface facing the comb-tooth portion 21 of the first electrode 11.

[0082] In Modification 1, the anode of the diode D1a as the first rectifying element and the cathode of the diode D2a as the second rectifying element are electrically connected to the first electrode 11. On the other hand, the anode of the diode D2a is electrically connected to the second electrode 12. One end Vi1 on the input side of the output unit 30 including the capacitor C1 and the voltage converter VC is electrically connected to the cathode of the diode D1a, and the other end Vi2 on the input side of the output unit 30 is electrically connected to the anode of the diode D2a and the second electrode 12.

[0083] Thus, similarly to the first embodiment, in the AC power generated by the vibration power generating element 10, when the first electrode 11 is at a negative potential and the second electrode 12 is at a positive potential, the diode D2a is forward biased, and current flows through the diode D2a from the second electrode 12 to the first electrode 11. In this case, the diode D1a is reverse biased, so no current flows through the output unit 30. On the other hand, when the first electrode 11 is at a positive potential and the second electrode 12 is at a negative potential, current flows from the first electrode 11 to the second electrode 12 through the diode D1a and the output unit 30, and the diode D2a is forward biased, so no current flows through the diode D2a.

[0084] The diode D1a and the output unit 30 constitute a half-wave rectifier 40a.

[0085] Therefore, in Modification 1, similarly to the first embodiment, in the vibration state where the electret second electrode 12 is at a negative potential and the first electrode 11 is at a positive potential, the electric field between the first electrode 11 and the second electrode 12 can be kept from being weakened. Therefore, compared with the conventional vibration power generation device, the energy of the environmental vibration can be converted into electrical energy with higher efficiency.

[0086] In the first embodiment and variation 1 described above, a negatively charged electret is formed on the surface of the second electrode 12 facing the first electrode 11 , but the present invention is not limited thereto and a positively charged electret may be formed on the surface of the first electrode 11 facing the second electrode 12 .

[0087] In this case as well, as described above, it is possible to prevent electric power from being extracted from the vibration power generating element 10 in a state where the electric field E2 between the first electrode 11 and the second electrode 12 is weakened, and thus it is possible to improve power generation efficiency.

[0088] Alternatively, a positive electret may be formed on the first electrode 11 , and a negative electret may be formed on the second electrode 12 .

[0089] (Effects of the First Embodiment and Modification 1)

[0090] (1) The vibration power generating device 100, 100a of the above-mentioned first embodiment and modification 1 comprises: a first electrode 11; a second electrode 12 opposite to the first electrode 11; a holding portion 14 for holding at least one of the first electrode 11 and the second electrode 12 in a relatively movable manner; a half-wave rectifier 40 for allowing a current flowing from the first electrode 11 to the second electrode 12 to flow through the output portion 30; a diode (second rectifying element) D2 for allowing a current flowing from the second electrode 12 to flow to the first electrode 11 and cutting off a current flowing from the first electrode 11 to the second electrode 12, and the first electrode 11 has a positively charged electret on the surface of the surface opposite to the second electrode 12, or the second electrode 12 has a negatively charged electret on the surface of the surface opposite to the first electrode 11.

[0091] According to this configuration, it is possible to realize a vibration power generating device that efficiently converts environmental vibration into electric energy.

[0092] (Second Embodiment)

[0093] Figure 5 1 is a schematic diagram showing a schematic structure of a vibration power generating device 100b according to a second embodiment of the present invention. In addition, the same reference numerals are used for the same structures as those in the first embodiment, and the description thereof will be omitted.

[0094] The vibration power generating element 10b included in the vibration power generating device 100b of the second embodiment is different from the first embodiment in that it includes two pairs of electrodes formed with electrets and two pairs of electrodes not formed with electrets, and includes two first rectifying elements and two second rectifying elements.

[0095] The second electrode 12a and the second electrode 12b, which are two fixed electrodes, are fixed to the inner sides of the ends of the support frame 13 on the +X side and the -X side, respectively. On the other hand, the first electrode 11a and the first electrode 11b, which are two movable electrodes, are provided on the +X side and the -X side, respectively, of the electrode holding portion 14a constituting the holding portion 14. Therefore, similarly to the first embodiment described above, when the holding portion 14 vibrates due to external vibration, the first electrodes 11a and 11b vibrate in the X direction relative to the second electrodes 12a and 12b. In the comb-tooth portions 22a and 22b of the second electrodes 12a and 12b, respectively, an electret having a negative charge is formed in the surface regions 25a and 25b of the surfaces of the surfaces facing the comb-tooth portions 21a and 21b of the first electrodes 11a and 11b.

[0096] In the vibration power generating element 10b, the support frame 13 can be interpreted as a first holding portion that integrally holds the two first electrodes 11a and 11b. The electrode holding portion 14a can be interpreted as a second holding portion that integrally holds the two second electrodes 12a and 12b. The connecting portion 14b can be interpreted as a relatively movable portion that allows the two first electrodes 11a and 11b and the two second electrodes 12a and 12b to move freely relative to each other.

[0097] In the second embodiment, as in the first embodiment, a diode as a rectifying element and an output unit 30 are connected to each electrode in a predetermined relationship. A cathode of a diode D1c as a first rectifying element and an anode of a diode D2c as a second rectifying element are electrically connected to one second electrode 12a. A cathode of a diode D1d as a first rectifying element and an anode of a diode D2d as a second rectifying element are electrically connected to the other second electrode 12b.

[0098] One end Vi1 on the input side of the output unit 30 including the capacitor C1 and the voltage converter VC is electrically connected to the anodes of the diodes D1c and D1d.

[0099] The two first electrodes 11a and 11b are electrically connected. Furthermore, the cathodes of the diodes D2c and D2d as the second rectifying elements and the other end Vi2 on the input side of the output unit 30 are electrically connected to the two first electrodes 11a and 11b. The potential of the two first electrodes 11a and 11b is the ground potential.

[0100] In addition, the first electrode 11a and the first electrode 11b are held by the holding portion 14 as a whole and vibrate in the X direction. Therefore, in each phase of vibration, when the area where the first electrode 11a and the second electrode 12a face each other increases, the area where the first electrode 11b and the second electrode 12b face each other decreases. Therefore, the phase of the potential of the first electrode 11a and the first electrode 11b is reversed with respect to the potential of the second electrode 12a and the second electrode 12b which are the common ground potential.

[0101] The structure of the second embodiment can also be considered as a structure in which two vibration power generation elements 10, a diode D1 as a first rectifying element, and a diode D2 as a second rectifying element are arranged in parallel in the vibration power generation device 100 of the first embodiment. In this parallel arrangement, only one holding part 14 and one output part 30 are arranged respectively, and they become the common parts of the two parallel structures.

[0102] Therefore, due to the rectifying characteristics of the diodes D1c and D1d and the diodes D2c and D2d, in the second embodiment, as in the first embodiment, the electric field between the first electrode 11 and the second electrode 12 can be kept from being weakened in the vibration state where the electret second electrode 12 is at a negative potential and the first electrode 11 is at a positive potential. Therefore, compared with the conventional vibration power generation device, the energy of the environmental vibration can be converted into electric energy with higher efficiency.

[0103] Furthermore, since the vibration power generating element 10 b of the second modification is configured such that two vibration power generating elements are arranged in parallel, it is possible to convert the energy of the environmental vibration into electric energy with higher efficiency.

[0104] The diode D1c and the output section 30, and the diode D1d and the output section 30 respectively constitute a half-wave rectifier 40b.

[0105] In the above description, the first electrodes 11a and 11b are formed of two separate electrodes, but the first electrodes 11a and 11b may be formed as one integrated electrode. Figure 5 The first electrodes 11a and 11b are formed as one continuous electrode, and the holding portion 14 holds the first electrode integrated from the upper surface or the periphery thereof. In this case, there is an effect of simplifying the formation process of the first electrodes 11a and 11b.

[0106] (Variant 2)

[0107] Reference Figure 6 , a vibration power generating device 100c of Modification 2 will be described. In addition, the same reference numerals are used for the same structures as those of the first embodiment, the second embodiment or Modification 1, and the description thereof will be omitted.

[0108] The vibration power generating device 100c of variant example 2 has a structure substantially the same as that of the vibration power generating element 10b of the second embodiment described above, but differs from the vibration power generating element 10b of the second embodiment in that the second electrodes 12a and 12b forming the electret with negative charge become movable electrodes, and that the cathode and anode of the diodes D1e, D1f, D2e, and D2f are oriented in opposite directions.

[0109] The first electrode 11a and the first electrode 11b, which are two fixed electrodes, are fixed to the inner sides of the ends of the support frame 13 on the +X side and the -X side, respectively. On the other hand, the second electrode 12a and the second electrode 12b, which are two movable electrodes, are provided on the +X side and the -X side, respectively, of the electrode holding portion 14a constituting the holding portion 14. Therefore, similarly to the above-mentioned second embodiment, when the holding portion 14 vibrates due to vibration from the outside, the first electrodes 11a and 11b vibrate opposite to the second electrodes 12a and 12b in the X direction. In the regions 25a and 25b of the surfaces of the comb-tooth portions 22a and 22b of the second electrodes 12a and 12b, which face the comb-tooth portions 21a and 21b of the first electrodes 11a and 11b, negatively charged electrets are formed.

[0110] In the second modification, as in the second embodiment, a diode as a rectifying element and an output unit 30 are connected to each electrode in a predetermined relationship. The anode of the diode D1e as a first rectifying element and the cathode of the diode D2e as a second rectifying element are electrically connected to the first electrode 11a on one side. The anode of the diode D1f as a first rectifying element and the cathode of the diode D2f as a second rectifying element are electrically connected to the first electrode 11b on the other side.

[0111] One end Vi1 on the input side of the output unit 30 including the capacitor C1 and the voltage converter VC is electrically connected to the cathodes of both the diode D1e and the diode D1f.

[0112] The two second electrodes 12a and 12b are electrically connected. In addition, the anodes of the diodes D2e and D2f as the second rectifying elements and the other end Vi2 on the input side of the output unit 30 are electrically connected to the two second electrodes 12a and 12b. The potential of the two second electrodes 12a and 12b is the ground potential.

[0113] In Modification 2, similarly to the second embodiment, the phases of the potentials of the second electrodes 12a and 12b are reversed with respect to the potentials of the first electrodes 11a and 11b which are the common ground potential.

[0114] The structure of Modification 2 can also be considered as a structure in which two vibration power generation elements 10a, a diode D1a as a first rectifying element, and a diode D2a as a second rectifying element are arranged in parallel in the vibration power generation device 100a of Modification 1. In this parallel arrangement, only one holding part 14 and one output part 30 are arranged respectively, and they become the common parts of the two parallel structures.

[0115] Therefore, due to the rectifying characteristics of the diodes D1e and D1f and the diodes D2e and D2f, in Modification 2, as in the first embodiment and Modification 1, the electric field between the first electrode 11 and the second electrode 12 can be kept from being weakened in the vibration state where the electret second electrode 12 is at a negative potential and the first electrode 11 is at a positive potential. Therefore, compared with the conventional vibration power generation device, the energy of the environmental vibration can be converted into electric energy with higher efficiency.

[0116] Furthermore, since the vibration power generating element 10 b of the second modification is configured such that two vibration power generating elements are arranged in parallel, it is possible to convert the energy of the environmental vibration into electric energy with higher efficiency.

[0117] The diode D1e and the output section 30, and the diode D1f and the output section 30 respectively constitute a half-wave rectifier 40c.

[0118] In addition, similarly to the second embodiment, the second electrodes 12a and 12b may be formed as one integrated electrode. In this case, the holding portion 14 may be configured to hold the integrated second electrode from its upper surface or periphery. In this case, the formation process of the second electrodes 12a and 12b is simplified.

[0119] In the second embodiment, the two first electrodes 11a and 11b are held as a whole by one electrode holding portion 14a, and in the second modification, the two second electrodes 12a and 12b are held as a whole by one electrode holding portion 14a, but the present invention is not limited thereto. That is, two holding portions 14 including the electrode holding portion 14a may be provided separately in the X direction, and each holding portion 14 holds one of the two electrodes.

[0120] In addition, the structure in which two electrodes (the first electrodes 11 a and 11 b or the second electrodes 12 a and 12 b ) are integrally held by one electrode holding portion 14 a is excellent in that the vibration power generating elements 10 b and 10 c can be miniaturized.

[0121] In the above second embodiment and variant example 2, the structure of forming a negatively charged electret on the surface of the second electrode 12 opposite to the first electrode 11 is not limited to this, and a structure of forming a positive electret on the surface of the first electrode 11 opposite to the second electrode 12 may also be adopted.

[0122] In this case as well, as described above, it is possible to prevent electric power from being extracted from the vibration power generating element 10 in a state where the electric field E2 between the first electrode 11 and the second electrode 12 is weakened, and thus it is possible to improve power generation efficiency.

[0123] Alternatively, a positive electret may be formed on the first electrode 11 , and a negative electret may be formed on the second electrode 12 .

[0124] (Effects of the Second Embodiment and Modification 2)

[0125] (2) The vibration power generating devices 100b and 100c of the above second embodiment and variant example 2 have, in addition to the structure of the vibration power generating device 100 of the first embodiment, two first electrodes 11a and 11b, two second electrodes 12a and 12b, two first rectifying elements (diodes) D1c, D1d, D1e and D1f, and two second rectifying elements (diodes) D2c, D2d, D2e and D2f.

[0126] Furthermore, one of the two first electrodes 11 a and 11 b or the two second electrodes 12 a and 12 b is electrically connected, and one end of each of the two second rectifying elements D2 c , D2 d , D2 e ​​, and D2 f is electrically connected.

[0127] The other of the two first electrodes 11a, 11b or the two second electrodes 12a, 12b is electrically connected to the other end of each of the two second rectifying elements D2c, D2d, D2e, D2f, and is electrically connected to one end of each of the two first rectifying elements D1c, D1d, D1e, D1f.

[0128] According to this configuration, it is possible to realize a vibration power generating device that can more efficiently convert environmental vibration into electric energy.

[0129] (3) Furthermore, in (2), the holding portion 14 can also be constructed to include: a first holding portion (support frame) 13, which holds the two first electrodes 11a and 11b as a whole; a second holding portion (electrode holding portion) 14a, which holds the two second electrodes 12a and 12b as a whole; and an opposing movable portion (connecting portion) 14b, which allows the two first electrodes 11a and 11b and the two second electrodes 12a and 12b to move freely relative to each other. In this case, the miniaturization of the vibration power generating element 10b can be achieved.

[0130] In any of the above-mentioned embodiments and modifications, the region 25 where the electret is formed may not be the entire portion of the surface of the second electrode 12 that faces the first electrode 11 , but may be a portion.

[0131] In addition, the number of the comb-teeth portions 21 and 22 of the first electrode 11 and the second electrode 12 is not limited to the above number, and several comb-teeth portions may be provided. In addition, the shapes of the first electrode 11 and the second electrode 12 are not limited to the above comb-teeth electrodes, and may be parallel plate-type electrodes arranged opposite to each other.

[0132] In addition, the diode D1 and the diode D2 may also be a diode obtained by connecting a plurality of diodes in series to increase the withstand voltage. In addition, the first rectifying element and the second rectifying element are not limited to diodes, and other electrical elements such as dipoles and spintronic rectifying elements that perform rectification by spintronic rectification may also be used.

[0133] Various embodiments and variations have been described above, 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 concept of the present invention are also included in the scope of the present invention.

[0134] The disclosures of the following priority basic applications are incorporated herein by reference.

[0135] Japanese Patent Application No. 90197, 2018 (filed on May 8, 2018)

[0136] Explanation of symbols

[0137] 100, 100a, 100b, 100c...vibration power generation device, 10, 10a, 10b, 10c...vibration power generation element, 11, 11a, 11b...first electrode, 12, 12a, 12b...second electrode, 13...support frame, 14...holding portion, D1, D1a, D1c, D1d, D1e, D1f...first rectifying element (diode), D2, D2a, D2c, D2d, D2e, D2f...second rectifying element (diode), C1...capacitor, VC...voltage conversion circuit, 30...output portion, 40, 40a, 40b, 40c...half-wave rectifier.

Claims

1. A vibration power generation device, characterized in that: include: a first electrode; a second electrode, opposite to the first electrode; a holding portion for holding at least one of the first electrode and the second electrode in a relatively movable manner; a half-wave rectifier including a first rectifying element and an output portion, electrically connected to the first electrode and the second electrode, allowing a current flowing from the first electrode to the second electrode to flow through the output portion, and cutting off a current flowing from the second electrode to the first electrode; as well as a second rectifying element electrically connected to the first electrode and the second electrode, allowing the current flowing from the second electrode to flow to the first electrode and blocking the current flowing from the first electrode to the second electrode, The second electrode has a negatively charged electret on a surface facing the first electrode. The first and second electrodes are provided with two each, the first and second rectifier elements are provided with two each, and One of the two first electrodes or the two second electrodes is electrically connected, and one end of each of the two second rectifying elements is electrically connected, The other of the two first electrodes or the two second electrodes, which is different from the one, is electrically connected to the other end different from the one end of each of the two second rectifying elements and is electrically connected to one end of each of the two first rectifying elements. The second rectifying element is a diode, The cathodes of the two diodes serving as the second rectifying elements are directly connected to the first electrode without passing through the output unit. Anodes of the two diodes serving as the second rectifying elements are directly connected to the second electrode without passing through the output unit.

2. The vibration power generation device according to claim 1, characterized in that: The holding portion has: A first holding portion integrally holds the two first electrodes; a second holding portion integrally holding the two second electrodes; and The relative moving part enables the two first electrodes and the two second electrodes to move freely relative to each other.

3. The vibration power generation device according to claim 1 or 2, characterized in that: The output unit includes a capacitor and a voltage conversion circuit arranged in parallel with the capacitor.

4. The vibration power generation device according to claim 1 or 2, characterized in that: The first rectifying element is a diode.

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