Ambient power generation device

Abstract

The ambient power generation device includes: an energy conversion element that converts the energy of the environment into electric power; an ambient sensor that is disposed in the same environment as the energy conversion element; and a power supply circuit that is input with the electric power converted by the energy conversion element and outputs the electric power to the outside, and the power supply circuit changes its operation conditions corresponding to the output of the ambient sensor.

Description

Technical Field

[0001] The present invention relates to an environmental power generation device. Background Art

[0002] As an environmental power generation device for harvesting weak energy existing in the environment and converting it into electric power, that is, a so-called energy harvesting environmental power generation device, solar power generation, thermal power generation, and a method of generating power from environmental vibration using a MEMS (Microelectromechanical Systems) vibration element, that is, a vibration power generation element, are known. (See Patent Document 1).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-74817 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] Since the energy existing in the environment is weak, a vibration power generation device that converts environmental energy into electric power with low loss is sought.

[0008] Means for Solving the Problems

[0009] The environmental power generation device of the first aspect includes: an energy conversion element that converts environmental energy into electric power; an environmental sensor that is disposed in the same environment as the energy conversion element; and a power supply circuit that is input with the electric power converted by the energy conversion element and outputs the electric power to the outside, and the power supply circuit changes operating conditions corresponding to the output of the environmental sensor.

[0010] The environmental power generation device of the second aspect preferably changes the operating conditions corresponding to the real-time output from the environmental sensor on the basis of the environmental power generation device of the first aspect.

[0011] The environmental power generation device of the third aspect preferably changes the connection conditions of the circuit corresponding to the output of the environmental sensor on the basis of the environmental power generation device of the first or second aspect, and the energy conversion element is an element that generates AC power, and the power supply circuit includes a rectifier circuit that rectifies the AC power converted by the energy conversion element, and the rectifier circuit includes a switching element.

[0012] The environmental power generation device of the fourth aspect preferably outputs an AC signal having the same frequency as the AC power converted by the energy conversion element from the environmental sensor on the basis of the environmental power generation device of the third aspect.

[0013] The environmental power generation device of the fifth mode is preferably based on the environmental power generation device of the fourth mode, and the power supply circuit has a voltage limiting circuit that limits the AC signal output by the environmental sensor to a voltage within a specified range.

[0014] The environmental power generation device of the sixth mode is preferably based on the environmental power generation device of the fifth mode, and the voltage limiting circuit includes a diode bridge circuit composed of MOSFETs.

[0015] The environmental power generation device of the seventh mode is preferably based on the environmental power generation device of the fifth mode, and the voltage limiting circuit includes: a dynamic comparator that is input with the AC signal output by the environmental sensor; and a storage circuit that stores the output of the dynamic comparator.

[0016] The environmental power generation device of the eighth mode is preferably based on the environmental power generation device of the seventh mode, and the voltage limiting circuit has two rectifying elements with anodes and cathodes reversed and connected in parallel on the input side of the dynamic comparator.

[0017] The environmental power generation device of the ninth mode is preferably based on the environmental power generation device of the first mode or the second mode, and the power supply circuit has a current-voltage conversion circuit that outputs a voltage signal corresponding to the amount of current output by the environmental sensor, and the power supply circuit changes its operating conditions according to the output voltage from the current-voltage conversion circuit.

[0018] The environmental power generation device of the tenth mode is preferably based on the environmental power generation device of the ninth mode, and the current-voltage conversion circuit includes a circuit in which a plurality of voltage detection circuits are connected in series, and the power supply circuit changes its operating conditions according to the detection signals from the plurality of voltage detection circuits. The voltage detection circuit includes a pair of rectifying elements with anodes and cathodes reversed and connected in parallel, and a detection circuit that detects the voltage at one end of the pair of rectifying elements.

[0019] The environmental power generation device of the eleventh mode is preferably based on the environmental power generation device of any one of the first mode to the eleventh mode, and the energy conversion element and the environmental sensor are vibration power generation elements.

[0020] Advantages of the Invention

[0021] According to the present invention, weak energy existing in the environment can be efficiently converted into electric energy. Description of the Drawings

[0022] Figure 1 It is a diagram showing the schematic structure of the environmental power generation device 1 of the first embodiment.

[0023] Figure 2This is a schematic diagram showing the vibration power generation unit 10 of the ambient power generation device 1.

[0024] Figure 3 This is a diagram showing the schematic structure of the ambient power generation device 1a of the second embodiment.

[0025] Figure 4 This is a diagram showing an example of the circuit diagram of the dynamic comparator.

[0026] Figure 5 This is a diagram showing an example of the logic diagram of the storage circuit.

[0027] Figure 6 This is a diagram showing the schematic structure of the ambient power generation device 1b of the third embodiment.

[0028] Figure 7 This is a diagram showing the relationship between the voltage and current (IV characteristics) of each part in the current-voltage conversion circuit 70. Detailed Embodiment

[0029] (Ambient Power Generation Device of the First Embodiment)

[0030] Hereinafter, with reference to Figure 1 and Figure 2 the ambient power generation device 1 of the first embodiment will be described.

[0031] Figure 1 This is a diagram showing the schematic structure of the ambient power generation device 1 of the first embodiment. The ambient power generation device 1 includes: a vibration power generation unit 10 that generates AC power through ambient vibration; and a power supply circuit 80 that extracts the generated AC power and outputs it to an external device or the like.

[0032] The power supply circuit 80 includes: a voltage limiting circuit 40, a rectifying circuit 50, a voltage conversion circuit 60, a first capacitor C1, and a second capacitor C2, which will be described later.

[0033] As an example, the vibration power generation unit 10 is an electrostatic capacitance type power generation element (electret type power generation element) having an electret electrode. With reference to Figure 2 its outline will be described.

[0034] The vibration power generation unit 10 includes a first electrode 11 as a fixed electrode and a second electrode 12 as a movable electrode. The first electrode 11 and the second electrode 12 constitute an example of an energy conversion element that converts energy in the environment into electric energy, that is, a vibration power generation element. In this specification, the first electrode 11 and the second electrode 12 are also collectively referred to as the energy conversion element 31.

[0035] As an example, the first electrode 11 is a comb electrode having six comb teeth portions 15, and as an example, the second electrode 12 is a comb electrode having five comb teeth portions 16. However, the number of comb teeth electrodes constituting the two electrodes is not limited to the above numbers.

[0036] The vibration power generation unit 10 also has a third electrode 21 as a fixed electrode and a fourth electrode 22 as a movable electrode that are arranged in pairs at positions shifted in the Y direction from the pair of the first electrode 11 and the second electrode 12. The third electrode 21 and the fourth electrode 22 constitute a vibration power generation element as an example of an environmental sensor. In this specification, the third electrode 21 and the fourth electrode 22 are also collectively referred to as the environmental sensor 32.

[0037] As an example, the third electrode 21 is a comb electrode having two comb teeth portions 23, and as an example, the fourth electrode 22 is a comb electrode having one comb tooth portion 24. The number of comb teeth electrodes constituting the third electrode 21 and the fourth electrode 22 is not limited to the above numbers, and is a number smaller than the number of comb teeth electrodes constituting the above first electrode 11 and second electrode 12.

[0038] The output line W1 is connected to the first electrode 11, the output line W2 is connected to the second electrode 12, the output line W3 is connected to the third electrode 21, and the output line W4 is connected to the fourth electrode 22. The output lines W1 to W4 are formed of, for example, a metal such as gold that has a small resistance and is ductile.

[0039] In this specification, the term "connected" means that two objects are in an electrically conductive state directly or via a material with a low resistance such as metal.

[0040] The comb teeth portions 15, 16, 23, 24 of the first to fourth electrodes 11, 12, 21, 22 described above have a predetermined thickness in the Z direction in the figure, and the portions where they mesh are opposed to other electrodes. The first to fourth electrodes 11, 12, 21, 22 can be manufactured, for example, as MEMS structures based on silicon.

[0041] In the region 17 on the surface of the surface of the comb teeth portion 15 of the first electrode 11 that faces the comb teeth portion 16 of the second electrode 12, an electret having positive or negative charges is formed by performing a known charging treatment (for example, the charging treatment described in Japanese Patent Application Laid-Open No. 2014-049557). Similarly, an electret having positive or negative charges is formed in the region 25 on the surface of the surface of the comb teeth portion 23 of the third electrode 21 that faces the comb teeth portion 24 of the fourth electrode 22.

[0042] By electretization, the comb-shaped portions 15 of the first electrode 11 and the comb-shaped portions 23 of the third electrode 21 are semi-permanently charged. As a result, on the comb-shaped portions 16 of the second electrode 12 opposed to the electretized electrodes, induced charges with characteristics opposite to those of the electretized electrodes, that is, negative or positive induced charges, are induced. Similarly, on the comb-shaped portions 24 of the fourth electrode 22 opposed to the electretized electrodes, negative or positive induced charges are also induced.

[0043] The first electrode 11 and the third electrode 21 are integrally and fixedly held by an insulating support frame 13.

[0044] On the other hand, the second electrode 12 and the fourth electrode 22 are integrally held by a holding portion 14 (electrode holding portion 14a, connecting portion 14b, fixing portion 14c), and are held so as to vibrate in the vertical direction (X direction) in the drawing with respect to the support frame 13. The holding portion 14 is composed of an electrode holding portion 14a that holds the second electrode 12 and the fourth electrode 22, a fixing portion 14c fixed to the support frame 13, and a flexible connecting portion 14b that connects the electrode holding portion 14a and the fixing portion 14c.

[0045] The connecting portion 14b is a thin sheet made of a flexible material such as metal with a thin thickness in the X direction and a thick thickness in the Z direction in Figure 1 . When vibration is applied to the support frame 13 from the outside, the two connecting portions 14b on the left and right of the electrode holding portion 14a provided in the drawing are flexed, whereby the electrode holding portion 14a vibrates in the X direction with respect to the support frame 13. As a result, the second electrode 12 held by the electrode holding portion 14a is configured to vibrate in the X direction with respect to the first electrode 11 fixed to the support frame 13. Similarly, the fourth electrode 22 held by the electrode holding portion 14a is configured to vibrate in the X direction with respect to the third electrode 21 fixed to the support frame 13.

[0046] When the vibration power generation unit 10 vibrates in the X direction, as the first electrode 11 and the second electrode 12 relatively move in the X direction, the area of the surface where the comb-shaped portions 15 of the first electrode 11 and the comb-shaped portions 16 of the second electrode 12 are opposed increases and decreases. As a result, due to the increase and decrease of this area, the induced charges of the electret also change, and the potential difference between the first electrode 11 and the second electrode 12 changes to generate an electromotive force. Thus, through the energy conversion element 31 (the first electrode 11 and the second electrode 12) as the vibration power generation element, the vibration energy is converted (generated) into electric energy.

[0047] When the vibration power generation unit 10 vibrates in the X direction, the third electrode 21 and the fourth electrode 22 of the environmental sensor 32 also move relatively in the X direction. Therefore, a current with the same sign as the current generated between the first electrode 11 and the second electrode 12 is also generated between the third electrode 21 and the fourth electrode 22.

[0048] The environmental sensor 32 is arranged in the same environment as the above-described energy conversion element 31 (the first electrode 11 and the second electrode 12). Therefore, the environmental sensor 32 generates and outputs a current, that is, an electrical signal, which accurately reflects the state of the power generated by the energy conversion element 31.

[0049] However, the number of comb teeth portions 23 and 24 included in the environmental sensor 32 is smaller than the number of comb teeth portions 15 and 16 included in the energy conversion element 31. Therefore, the power converted by the environmental sensor 32 is smaller than the power converted by the energy conversion element 31, roughly according to the ratio of the number of comb teeth portions.

[0050] Hereinafter, with reference to Figure 1 The description will be continued.

[0051] The other end of the output line W1 connected to the first electrode 11 constituting the energy conversion element 31 in the vibration power generation unit 10 is connected to the first input portion P5 of the rectifier circuit 50 included in the power supply circuit 80. On the other hand, the other end of the output line W2 connected to the second electrode 12 is connected to the second input portion P6 of the rectifier circuit 50.

[0052] Since the energy conversion element 31 as a vibration power generation element generates AC power, in order to efficiently use this power, it is preferable to convert the AC into DC.

[0053] As an example, the rectifier circuit 50 includes four switching elements M1 to M4 formed of nMOSFETs. Among the switching elements M1 to M4, the electrode marked with the symbol S represents the source electrode, the electrode marked with the symbol G represents the gate electrode, and the electrode marked with the symbol D represents the drain electrode.

[0054] When a positive voltage is input to the first control input portion Pa of the rectifier circuit 50, a positive voltage is applied to the gate G of the switching element M1, so that the first input portion P5 and the first output portion P7 are turned on, and a positive voltage is applied to the gate G of the switching element M2, so that the second input portion P6 and the second output portion P8 are turned on.

[0055] On the other hand, when a negative voltage is input to the first control input portion Pa, a negative voltage is applied to the gate G of the switching element M1, so that the first input portion P5 and the first output portion P7 are turned off, and a negative voltage is applied to the gate G of the switching element M2, so that the second input portion P6 and the second output portion P8 are turned off.

[0056] When a positive voltage is input to the second control input unit Pb of the rectifying circuit 50, a positive voltage is applied to the gate G of the switching element M3, causing the first input unit P5 and the second output unit P8 to conduct, and a positive voltage is applied to the gate G of the switching element M4, causing the second input unit P6 and the first output unit P7 to conduct.

[0057] On the other hand, when a negative voltage is input to the second control input unit Pb, a negative voltage is applied to the gate G of the switching element M3, causing the first input unit P5 and the second output unit P8 to disconnect, and a negative voltage is applied to the gate G of the switching element M4, causing the first input unit P5 and the first output unit P7 to disconnect.

[0058] Therefore, when the first input unit P5 has a positive voltage and the second input unit P6 has a negative voltage, a positive voltage is applied to the first control input unit Pa and a negative voltage is applied to the second control input unit Pb. Thus, the voltage of the first output unit P7 can be set higher than that of the second output unit P8. On the other hand, when the first input unit P5 has a negative voltage and the second input unit P6 has a positive voltage, a negative voltage is applied to the first control input unit Pa and a positive voltage is applied to the second control input unit Pb. Thus, similarly, the voltage of the first output unit P7 can be set higher than that of the second output unit P8. That is, by applying a negative voltage to the first control input unit Pa and the above voltage to the second control input unit Pb, the rectified power can be output from the first output unit P7 and the second output unit P8.

[0059] In conventional ambient power generation devices, as the rectifying circuit, a bridge circuit composed of four diodes and a synchronous rectifying circuit using MOSFETs similar to the rectifying circuit 50 have been used.

[0060] However, in the rectifying circuit composed of diodes, a part of the power converted by the energy conversion element is consumed by the diodes.

[0061] On the other hand, in the conventional synchronous rectifying circuit using MOSFETs, the AC power generated by the energy conversion element is used to generate a control voltage signal for synchronous control of the MOSFETs. Therefore, conventionally, a part of the AC power generated by the energy conversion element is consumed for generating the control voltage signal.

[0062] Therefore, in conventional ambient power generation devices, the vibration energy harvested by the vibration power generation unit cannot be efficiently converted into electrical energy and output.

[0063] On the other hand, in the rectifier circuit 50 included in the ambient power generation device 1 of the first embodiment, an electrical signal generated and output by the ambient sensor 32 different from the energy conversion element 31 and whose voltage value is limited by the voltage limiting circuit 40 is used as a control signal for controlling the switching elements M1 to M4.

[0064] Thereby, the ambient power generation device 1 of the first embodiment can efficiently convert the vibration energy harvested by the vibration power generation unit 10 into electric energy.

[0065] Hereinafter, the reason why the ambient sensor 32 and the voltage limiting circuit 40 in the ambient power generation device 1 of the first embodiment can reduce the loss of the vibration energy harvested by the vibration power generation unit 10 and generate a control signal for the switching elements M1 to M4 will be described.

[0066] The other end of the output line W3 connected to the third electrode 21 constituting the ambient sensor 32 in the vibration power generation unit 10 is connected to the first input part P1 of the voltage limiting circuit 40 included in the power supply circuit 80. And the first input part P1 of the voltage limiting circuit 40 is connected to the first control input part Pa of the rectifier circuit 50.

[0067] On the other hand, the other end of the output line W4 connected to the fourth electrode 22 constituting the ambient sensor 32 is connected to the second input part P2 of the voltage limiting circuit 40. And the second input part P2 of the voltage limiting circuit 40 is connected to the second control input part Pb of the rectifier circuit 50.

[0068] As Figure 1 shown, the voltage limiting circuit 40 includes a bridge circuit composed of a plurality of control elements T1 to T8, and the plurality of control elements T1 to T8 are respectively composed of MOSFETs. As an example, all 8 control elements T1 to T8 are normally-off nMOSFETs. The electrode marked with the symbol S represents the source electrode, the electrode marked with the symbol G represents the gate electrode, and the electrode marked with the symbol D represents the drain electrode.

[0069] The middle part P3 and the middle part P4 of the bridge circuit composed of 8 control elements T1 to T8 are short-circuited and grounded.

[0070] The first input part P1 is connected to the source S and the gate G of the control element T1. The drain D of the control element T1 is connected to the source S and the gate G of the control element T2. The drain D of the control element T2 is connected to the middle part P4.

[0071] The middle part P4 is also connected to the drain D of the control element T6. The source S and the gate G of the control element T6 are connected to the drain D of the control element T5. The source S and the gate G of the control element T5 are connected to the second input part P2.

[0072] The first input unit P1 is also connected to the drain D of the control element T3. The source S and gate G of the control element T3 are connected to the drain D of the control element T4. The source S and gate G of the control element T4 are connected to the intermediate part P3.

[0073] The intermediate part P3 is also connected to the source S and gate G of the control element T8. The drain D of the control element T8 is connected to the source S and gate G of the control element T7. The drain D of the control element T7 is connected to the second input unit P2.

[0074] With the above structure of the voltage limiting circuit 40, when a positive voltage is input to the first input unit P1, the control elements T1 and T2 are turned on, and the upper limit of the voltage of the first input unit P1 is limited to the sum of the threshold voltages of the control elements T1 and T2. On the other hand, when a negative voltage is input to the first input unit P1, the control elements T3 and T4 are turned on, and the lower limit (negative upper limit) of the voltage of the first input unit P1 is limited to the sum of the threshold voltages of the control elements T3 and T4.

[0075] When a positive voltage is input to the second input unit P2, the control elements T5 and T6 are also turned on, and the upper limit of the voltage of the second input unit P2 is limited to the sum of the threshold voltages of the control elements T5 and T6. And when a negative voltage is input to the second input unit P2, the control elements T7 and T8 are turned on, and the lower limit (negative upper limit) of the voltage of the second input unit P2 is limited to the sum of the threshold voltages of the control elements T7 and T8.

[0076] Therefore, the upper limit value and the lower limit value of the voltage of the output from the environmental sensor 32 are limited by the voltage limiting circuit 40 to a specified voltage determined by the threshold voltages of the control elements T1 to T8. And when the output from the environmental sensor 32 exceeds the above-specified voltage, since the first input unit P1 and the second input unit P2 are in a conducting state due to any one or more of the control elements T1 to T8, they are connected with an extremely small resistance.

[0077] As a result, the energy of vibration consumed by the environmental sensor 32 is sufficiently small compared with the energy of vibration converted into electric energy by the energy conversion element 31. Therefore, even if all the vibration energy of the environmental sensor 32 is consumed, it will not affect the efficiency of the energy conversion element 31.

[0078] Thus, the energy of vibration harvested by the vibration power generation unit 10 including the environmental sensor 32 and the energy conversion element 31 is efficiently charged to C1. Therefore, the weak vibration energy existing in the environment can be efficiently converted into electric energy by the energy conversion element 31.

[0079] In addition, the number of control elements T1 to T8 (MOSFETs) arranged between the first input section P1 and the intermediate section P3 or P4 of the voltage limiting circuit 40, and between the second input section P2 and the intermediate section P3 or P4 is not limited to the above-mentioned two. Any number of control elements T1 to T8 corresponding to the upper and lower limit values of the voltage to be limited by the voltage limiting circuit 40 can also be arranged.

[0080] Through the rectifying action of the rectifying circuit 50, electric power with the voltage of the first output section P7 being positive with respect to the second output section P8 is output from the rectifying circuit 50. The first output section P7 of the rectifying circuit 50 is connected to the first input section Vin1 of the voltage conversion circuit 60, and the second output section P8 of the rectifying circuit 50 is connected to the second input section Vin2 of the voltage conversion circuit 60. In addition, the first output section P7 and the second output section P8 of the rectifying circuit 50 are respectively connected to both ends of the first capacitor C1.

[0081] As an example, the voltage conversion circuit 60 is a DC / DC converter using a chopper or the like, which converts the voltage input between the first input section Vin1 and the second input section Vin2 into a specified voltage and outputs it from the output section Vout. The output section Vout and the ground section GND are respectively connected to both ends of the second capacitor C2.

[0082] Under the same vibration conditions as the electric power from the energy conversion element 31 to be rectified, it is output to the gates G of the respective switching elements M1 to M4 in the rectifying circuit 50 by the environment sensor 32, and a real-time output having the same phase as the electric power from the energy conversion element 31 is supplied.

[0083] Therefore, the power supply circuit 80 including the rectifying circuit 50 can efficiently output the electric power from the energy conversion element 31 to the outside.

[0084] In addition, the voltage conversion circuit 60 is a circuit for converting the electric power output from the rectifying circuit 50 into a voltage suitable for the external load RO. Therefore, when the voltage suitable for the external load RO is consistent with the output voltage of the rectifying circuit 50, or when the external load RO itself has a function of converting the voltage, the power supply circuit 80 does not need to have the voltage conversion circuit 60. In addition, when the external load RO has a capacitor equivalent to the second capacitor C2, the power supply circuit 80 does not need to have the second capacitor C2.

[0085] The environmental power generation device 1 of the first embodiment described above has a voltage limiting circuit 40, but the voltage limiting circuit 40 may be omitted. In this case, the other end of the output line W3 connected to the third electrode 21 constituting the environmental sensor 32 in the vibration power generation unit 10 is connected to the first control input unit Pa of the rectifying circuit 50, and the other end of the output line W4 connected to the fourth electrode 24 is connected to the second control input unit Pb of the rectifying circuit 50.

[0086] By omitting the voltage limiting circuit 40, the resistance value of the circuit connected to the environmental sensor 32 increases. However, in this case, the energy of vibration consumed by the environmental sensor 32 is small enough when viewed from the overall power generation amount, so no significant energy loss occurs.

[0087] The environmental power generation device 1 of the first embodiment described above includes: an energy conversion element 31 that converts environmental energy into electric energy; and an environmental sensor 32 that is disposed in the same environment as the energy conversion element 31. And it includes: a power supply circuit 80 that is input with the power converted by the energy conversion element 31 and outputs the power to the outside, and the rectifying circuit 50 included in the power supply circuit 80 changes the rectifying condition, which is an example of the operating condition, according to the output of the environmental sensor 32.

[0088] (Environmental power generation device of the second embodiment)

[0089] Hereinafter, with reference to Figures 3 to 5 The environmental power generation device 1a of the second embodiment will be described. Most of the structure of the environmental power generation device 1a of the second embodiment is the same as that of the environmental power generation device 1 of the first embodiment described above. Therefore, the same reference numerals are given to the same structures, and the description is appropriately omitted.

[0090] Figure 3 FIG. is a schematic diagram showing the schematic structure of the environmental power generation device 1a of the second embodiment. For the environmental power generation device 1a of the second embodiment, the structure of the voltage limiting circuit 40a constituting the power supply circuit 80a is different from that of the environmental power generation device 1 of the first embodiment described above.

[0091] The voltage limiting circuit 40a is configured to include: a dynamic comparator 41 that operates in synchronization with the supplied clock signal CLK; and a storage circuit 42 that stores the output of the dynamic comparator 41. And on the input side of the dynamic comparator 41, there are two rectifying elements Da and Db with anodes and cathodes reversed and connected in parallel.

[0092] The other end of the output line W3 connected to the third electrode 21 constituting the environmental sensor 32 in the vibration power generation unit 10 is connected to the first input section P11 of the voltage limiting circuit 40a. On the other hand, the other end of the output line W4 connected to the fourth electrode 22 is connected to the second input section P12 of the voltage limiting circuit 40a.

[0093] The first input section P11 is connected to the cathode of a rectifying element Da such as a diode and the anode of a rectifying element Db. The second input section P12 is connected to the anode of the rectifying element Da and the cathode of the rectifying element Db.

[0094] The first input section P11 is also connected to the first input terminal Via of the dynamic comparator 41, and the second input section P12 is also connected to the second input terminal Vib of the dynamic comparator 41.

[0095] Two outputs Vma and Vmb from the dynamic comparator 41 are connected to the storage circuit 42. And, two outputs Voa and Vob from the storage circuit 42 are respectively connected to the first control input section Pa and the second control input section Pb of the rectifying circuit 50.

[0096] Figure 4 FIG. is an example of a circuit diagram showing the dynamic comparator 41. The dynamic comparator 41 is a circuit including elements Te, Tf, Tg, Tk, Tl as nMOSFETs and elements Ta, Tb, Tc, Td, Th, Ti, Tj as pMOSFETs. A power supply voltage VS and a clock signal CLK are supplied from the outside. A part of the clock signal CLK is input to the gates of the elements Th and Tk via an inverter (NOT) circuit Nc.

[0097] In addition, details of the structure of the dynamic comparator are disclosed, for example, in Japanese Patent Laid-Open No. 2017-46046, etc., and thus, detailed description thereof is omitted herein.

[0098] The dynamic comparator 41 compares only the magnitudes of the voltages of the signals respectively input to the first input terminal Via and the second input terminal Vib when the clock signal CLK supplied from the outside is a positive voltage, and outputs the comparison result to the outputs Vma and Vmb. In addition, the stages preceding the outputs Vma and Vmb are respectively connected to inverter circuits Na and Nb.

[0099] As an example, if the voltage of the first input terminal Via is more positive than the voltage of the second input terminal Vib, a positive voltage is output to the output Vma, and a ground potential is output to the output Vmb. Conversely, if the voltage of the first input terminal Via is more negative than the voltage of the second input terminal Vib, a ground potential is output to the output Vma. A positive voltage is output to the output Vmb.

[0100] The outputs Vma and Vmb of the dynamic comparator 41 are output only when the clock signal CLK is at a positive voltage. Therefore, this output is stored by the storage circuit 42.

[0101] Figure 5 FIG. is an example of a logic diagram showing the storage circuit 42. As an example, the storage circuit 42 is a so-called NOR-type flip-flop circuit that stores and holds whether the input Vma and the input Vmb are a positive voltage and a 0 voltage, or a 0 voltage and a positive voltage.

[0102] As described above, the two outputs Voa and Vob from the storage circuit 42 are respectively input to the first control input section Pa and the second control input section Pb of the rectifying circuit 50.

[0103] Therefore, in the ambient power generation device 1a of the second embodiment, the rectifying circuit 50 rectifies the AC power generated by the energy conversion element 31 according to the output of the dynamic comparator 41.

[0104] The power supply voltage VS required for the operation of the dynamic comparator 41 can be supplied, for example, by a part of the power for charging the second capacitor C2. In addition, the clock generation circuit that generates the clock signal CLK can also be driven by a part of the power for charging the second capacitor C2.

[0105] As an example, the period of the clock signal CLK is a frequency that is about 5 to 10 times or more the frequency of the AC power generated by the energy conversion element 31, that is, the frequency of vibration of the second electrode 12.

[0106] The dynamic comparator 41 operates only when the externally supplied clock signal CLK is at a positive voltage. Therefore, by using a clock signal CLK with a small duty cycle (On / Off ratio), the power required for the operation of the dynamic comparator 41 can be minimized. As a result, the vibration energy harvested by the vibration power generation unit 10 including the ambient sensor 32 and the energy conversion element 31 can be efficiently used for power generation by the energy conversion element 31.

[0107] In addition, the rectifying elements Da and Db arranged on the input side of the dynamic comparator 41 are used to limit the input voltage to the first input section Via and the second input section Vib of the dynamic comparator 41, but can be omitted if input voltage limitation is not required.

[0108] (Ambient Power Generation Device of the Third Embodiment)

[0109] Hereinafter, refer to Figure 6The environmental power generation device 1b of the third embodiment will be described. Most of the structures of the environmental power generation devices 1a of the third embodiment are the same as those of the environmental power generation device 1 of the first embodiment or the environmental power generation device 1a of the second embodiment described above. Therefore, the same symbols are assigned to the same structures, and the description is appropriately omitted.

[0110] Figure 6 FIG. is a diagram showing a schematic structure of the environmental power generation device 1b of the third embodiment. The difference between the environmental power generation device 1b of the third embodiment and the environmental power generation device 1 of the first embodiment and the environmental power generation device 1a of the second embodiment is that the power supply circuit 80b includes a current-voltage conversion circuit 70.

[0111] The rectifier circuit 50 included in the environmental power generation device 1b of the third embodiment is the same as the rectifier circuit 50 included in the environmental power generation device 1 of the first embodiment and the environmental power generation device 1a of the second embodiment. Therefore, Figure 6 detailed illustration is omitted.

[0112] In addition, the voltage limiting circuit 40 included in the environmental power generation device 1b of the third embodiment is the same as the voltage limiting circuit 40 included in the environmental power generation device 1 of the first embodiment or the voltage limiting circuit 40a included in the environmental power generation device 1a of the second embodiment. Therefore, Figure 6 detailed illustration is omitted.

[0113] In addition, the vibration power generation unit 10a is also different in that it has a second environmental sensor 33 in addition to the structure of the vibration power generation unit 10. The vibration power generation unit 10a has a structure similar to the vibration power generation unit 10 Figure 2 shown, and therefore, detailed illustration is omitted.

[0114] The vibration power generation unit 10a is adjacent to the environmental sensor 32 (the third electrode 21 and the fourth electrode 22) of the vibration power generation unit 10 in the Y direction shown in Figure 2 and has a second environmental sensor 33 that is the same as the environmental sensor 32.

[0115] The structure of the second environmental sensor 33 is the same as that of the environmental sensor 32. The fifth electrode 25 is fixed by the support frame 13, and the sixth electrode 26 is held by the electrode holding portion 14a and is movable in the Figure 2 X direction with respect to the fifth electrode 25. The fifth electrode 25 is integrally held with the first electrode 11 through the support frame 13, and the sixth electrode 26 is integrally held with the second electrode 12 through the electrode holding portion 14a.

[0116] On the surface of the surface of the fifth electrode 25 facing the sixth electrode 26, a electret having positive or negative charges is formed.

[0117] One end of the output line W5 is connected to the fifth electrode 25 that constitutes the second environmental sensor 33, and one end of the output line W6 is connected to the sixth electrode 26 that constitutes the second environmental sensor 33.

[0118] The other end of the output line W5 is connected to the first input section P13 of the current-voltage conversion circuit 70. The first input section P13 is also grounded. The other end of the output line W6 is connected to the second input section P16 of the current-voltage conversion circuit 70.

[0119] The voltage detection circuit 711 included in the current-voltage conversion circuit 70 includes a rectifier element pair (Dc, Dd) composed of rectifier elements such as diodes Dc and Dd, and a detection circuit CP1 that detects the voltage on the second input section P16 side of the rectifier element pair (Dc, Dd). The rectifier elements Dc and Dd are connected in parallel, and the anodes and cathodes are arranged in opposite directions to each other.

[0120] A voltage detection circuit 712 and a voltage detection circuit 713 having the same structure as the voltage detection circuit 711 are connected in series with the voltage detection circuit 711. The voltage detection circuit 712 includes a rectifier element pair composed of rectifier elements De and Df, and a detection circuit CP2 that detects the voltage at the end P15 on the rectifier element pair (Dc, Dd) side of the rectifier element pair (De, Df). The voltage detection circuit 713 includes a rectifier element pair composed of rectifier elements Dg and Dh, and a detection circuit CP3 that detects the voltage at the end P14 on the rectifier element pair (De, Df) side of the rectifier element pair (Dg, Dh).

[0121] A reference voltage Vref is supplied from a reference voltage generation circuit (not shown) to each of the detection circuits CP1 to CP3.

[0122] The detection circuits CP1 to CP3 respectively output detection signals V1 to V3 according to the detected voltages.

[0123] The detection circuits CP1 to CP3 are constituted by comparators including operational amplifiers, for example.

[0124] The forward voltages of the rectifier elements Dc and Dd included in the rectifier element pair of the voltage detection circuit 711, the rectifier elements De and Df included in the rectifier element pair of the voltage detection circuit 712, and the rectifier elements Dg and Dh included in the rectifier element pair of the voltage detection circuit 713 may be different from each other or the same.

[0125] The forward voltage refers to the voltage at which a large current starts to flow when a forward voltage is applied to the rectifier element.

[0126] In addition, the forward voltages of the rectifying elements Dc and Dd, the rectifying elements De and Df, and the rectifying elements Dg and Dh included in one rectifying element pair may be the same or different from each other.

[0127] Figure 7 FIG. is a diagram showing the relationship (IV characteristics) between the voltages of the respective parts in the current-voltage conversion circuit 70 and the current I when the current flows from the second input part P16 to the first input part P13. In addition, the logarithmic value (log) of the current I is set as the vertical axis of the graph. The IV characteristic IVc represents the relationship between the voltage Vc of the second input part P16 and the current I, that is, the IV characteristics of the three series-connected rectifying elements Dc, De, and Dg. The IV characteristic IVe represents the relationship between the voltage Ve of the end part P15 and the current I, that is, the IV characteristics of the two series-connected rectifying elements De and Dg. The IV characteristic IVg represents the relationship between the voltage Vg of the end part P14 and the current I, that is, the IV characteristics of the rectifying element Dg respectively.

[0128] When the current I gradually increases from 0, the increments of the three voltages Vc, Ve, and Vg are different from each other. Therefore, when the current values I are respectively equal to the reference voltage Vref serving as a reference, the comparators constituting the detection circuits CP1 to CP3 are respectively inverted, and the detection signals V1 to V3 change.

[0129] In addition, in this case, the rectifying elements Dd, Df, and Dh included in the current-voltage conversion circuit 70 are reverse-biased and no current flows through them.

[0130] As Figure 7 shown, when the current flowing from the second input part P16 to the first input part P13 is I1, a voltage V1c is generated at the second input part P16, a voltage V1e is generated at the end part P15, and a voltage V1g is generated at the end part P14. However, since the current I1 is small, the voltage V1e and the voltage V1g are 0V.

[0131] When the current flowing from the second input part P16 to the first input part P13 is I2, a voltage V2c is generated at the second input part P16, a voltage V2e is generated at the end part P15, and a voltage V2g is generated at the end part P14.

[0132] The voltages Vc, Ve, and Vg change corresponding to the amount of the current flowing from the second input part P16 to the first input part P13.

[0133] Therefore, it is possible to estimate the amount of the current flowing from the second input part P16 to the first input part P13 by using the detection signals V1 to V3 based on the voltages detected by the detection circuits CP1 to CP3.

[0134] Detection signals V1 to V3 from detection circuits CP1 to CP3 are input to control circuit 72. The control circuit 72 has, for example, an AD conversion circuit that converts the detection signals V1 to V3 into digital signals. The control circuit 72 estimates the amount of current flowing from the second input section P16 to the first input section P13, that is, the amount of current output from the second environmental sensor 33, based on the detection signals V1 to V3 that have been converted into digital signals.

[0135] Based on the estimated amount of current, the control circuit 72 supplies a control signal CS to the voltage conversion circuit 60 to change the operating conditions of the voltage conversion circuit 60. The operating conditions of the voltage conversion circuit 60 refer to, for example, the conditions for amplifying the voltage output to the output section Vout with respect to the voltage input between the first input section Vin1 and the second input section Vin2.

[0136] For example, if the voltage conversion circuit 60 is a circuit including a chopper, the operating conditions can be changed by changing the period during which the chopper operates.

[0137] In addition, instead of estimating the amount of current from the second environmental sensor 33 as described above, the control circuit 72 may change the operating conditions of the voltage conversion circuit 60 based on the detection signals V1 to V3.

[0138] Since the second environmental sensor 33 and the energy conversion element 31 are vibration power generation elements that are mechanically integrated with each other, the amount of current from the second environmental sensor 33 is substantially proportional to the power generation amount of the energy conversion element 31.

[0139] Therefore, in the environmental power generation device 1b of the third embodiment, the operating conditions of the voltage conversion circuit 60 can be set to optimal conditions corresponding to the power generation amount of the energy conversion element 31, and the efficiency of the environmental power generation device 1b including the voltage conversion circuit 60 can be improved.

[0140] The above-described environmental power generation device 1b of the third embodiment includes an energy conversion element 31 that converts environmental energy into electric power and a second environmental sensor 33 disposed in the same environment as the energy conversion element 31. And it includes a power supply circuit 80b that receives the electric power converted by the energy conversion element 31 and outputs the electric power to the outside, and the power supply circuit 80b changes its operating conditions corresponding to the output of the second environmental sensor 33.

[0141] In addition, the power supply circuit 80b changes its operating conditions corresponding to the real-time output of the second environmental sensor 33. With this configuration, even when the vibration time of the environment where the vibration power generation unit 10a is provided changes, the operating conditions of the power supply circuit 80b can be controlled under optimal conditions corresponding to the situation in real time, and the efficiency of the environmental power generation device 1b can be further improved.

[0142] The current-voltage conversion circuit 70 of the ambient power generation device 1b according to the third embodiment causes current to flow through a circuit in which a plurality of pairs of rectifying elements (Dc and Dd, De and Df, Dg and Dh) are connected in series, and detects the voltage generated across the pairs of rectifying elements, the anodes and cathodes of which are opposite to each other and are arranged in parallel. In this configuration, compared with the conventional configuration in which current is caused to flow through a resistor to detect the voltage generated across the resistor, a large voltage is not generated, and it is possible to respond to current changes over a wider range.

[0143] A large voltage is not generated on the circuit side, that is, the effect of suppressing the vibration of the second ambient sensor 33 can be minimized.

[0144] In addition, in the ambient power generation device 1b according to the third embodiment, the second ambient sensor 33 does not necessarily need to output a current having the same phase as the energy conversion element 31. Therefore, in the vibration power generation unit 10, the fifth electrode 25 of the second ambient sensor 33 and the first electrode 11 of the energy conversion element 31, and the sixth electrode 26 of the second ambient sensor 33 and the second electrode 12 of the energy conversion element 31 may not be integrally held.

[0145] In addition, in the above example, in the vibration power generation unit 10, the second ambient sensor 33 is provided separately from the ambient sensor 32, but the second ambient sensor 33 may be omitted, and the ambient sensor 32 may be used as the second ambient sensor 33.

[0146] Further, in the ambient power generation device 1b according to the third embodiment, the voltage limiting circuit 40 may be omitted, and the rectifying circuit 50 may be constituted by a rectifying circuit using a general diode. In the ambient power generation device 1b according to the third embodiment, the operating conditions of the voltage conversion circuit 60 are set to optimal conditions corresponding to the power generation amount of the energy conversion element 31. Therefore, ambient energy can be efficiently converted into electric energy. Therefore, even if a rectifying circuit using a diode is used as the rectifying circuit 50, an ambient power generation device with higher efficiency than in the past can be realized.

[0147] (Modification example)

[0148] Hereinafter, modification examples of the ambient power generation devices 1, 1a, and 1b according to the above-described embodiments will be described.

[0149] In the above description, the energy conversion element 31, the ambient sensor 32, or also the second ambient sensor 33 of the vibration power generation unit 10 are all constituted by vibration power generation elements. However, the ambient sensor 32 and the second ambient sensor 33 may also be elements other than vibration power generation elements that convert vibration such as an acceleration sensor into an electric signal.

[0150] In addition, the energy conversion element 31 is not limited to the above-described vibration power generation element. For example, it may also be a photoelectric conversion element such as a solar cell that converts light energy existing in the environment into electric energy. In this case, the environmental sensor 32 or also the second environmental sensor 33 is also formed of a photoelectric conversion element and is arranged in the same environment as the energy conversion element 31.

[0151] Alternatively, the energy conversion element 31 may be a thermoelectric power generation element that converts heat energy existing in the environment into electric energy. In this case, the environmental sensor 32 or also the second environmental sensor 33 is also formed of a thermoelectric power generation element and is arranged in the same environment as the energy conversion element 31.

[0152] Even in these cases, the environmental sensor 32 or the second environmental sensor 33 is constituted by a small-output sensor with a small energy consumption of the environment. And the operating conditions of the power supply circuits 80, 80a, 80b that output the electric power converted by the energy conversion element 31 to the outside are changed corresponding to the output of the environmental sensor 32 or the second environmental sensor 33. With this configuration, it is possible to efficiently convert the energy of the environment into electric energy and output it to the outside environment power generation device.

[0153] (Effects of each embodiment and modification)

[0154] (1) The environmental power generation devices 1, 1a, 1b of the above-described respective embodiments and modifications include: an energy conversion element 31 that converts the energy of the environment into electric energy; an environmental sensor 32 that is arranged in the same environment as the energy conversion element 31; and power supply circuits 80, 80a that are input with the electric power converted by the energy conversion element 31 and output the electric power to the outside, and the power supply circuits 80, 80a change the operating conditions corresponding to the output of the environmental sensor 32.

[0155] According to this configuration, it is possible to convert the weak energy in the environment into electric energy with low loss.

[0156] (2) Moreover, the power supply circuits 80, 80a are configured to change the operating conditions corresponding to the real-time output from the environmental sensor 32, whereby it is possible to further convert the weak energy in the environment into electric energy with low loss.

[0157] (3) And the energy conversion element 31 is an element that generates AC power, and the power supply circuits 80, 80a have a rectification circuit 50 that rectifies the AC power converted by the energy conversion element 31, and the rectification circuit 50 is configured to have switching elements M1 to M4 that change the rectification conditions corresponding to the output of the environmental sensor 32, whereby it is possible to further convert the weak energy in the environment into electric energy with low loss.

[0158] (4) Further, the environmental sensor 32 is configured to output an AC signal having the same frequency as the AC power converted by the energy conversion element 31, whereby the rectification efficiency of the rectifier circuit 50 can be improved.

[0159] (5) Further, the power supply circuits 80, 80a are configured to include a voltage limiting circuit 40 that limits the AC signal output by the environmental sensor 32 to a voltage within a specified range, whereby the amount of energy consumed as the electric energy emitted by the environmental sensor 32 in the weak energy existing in the environment can be reduced. Thus, the weak energy existing in the environment can be converted into electric energy by the energy conversion element 31 with low loss.

[0160] (6) Further, the voltage limiting circuit 40 is configured to include a bridge circuit (T11 to T8) composed of MOSFETs, whereby the amount of energy consumed by the environmental sensor 32 in generating electricity in the weak energy existing in the environment can be further reduced.

[0161] (7) Further, the voltage limiting circuit 40a is configured to include: a dynamic comparator 41, which is input with the AC signal output by the environmental sensor 32; and a storage circuit 42, which stores the output of the dynamic comparator 41, whereby the amount of energy consumed by the environmental sensor 32 in generating electricity in the weak energy existing in the environment can be further reduced.

[0162] (8) Further, the power supply circuit 80b has a current-voltage conversion circuit 70 that outputs a voltage signal corresponding to the amount of current output by the environmental sensor 32 (and the second environmental sensor 33), and the power supply circuit 80a is configured to change its operation conditions according to the output signal from the current-voltage conversion circuit 70, whereby the weak energy in the environment can be converted into electric energy with low loss.

[0163] (9) Further, the current-voltage conversion circuit 70 can also be configured to include a circuit in which a plurality of voltage detection circuits 711 to 713 are connected in series, and the power supply circuit 80b changes its operation conditions according to the detection signals from the plurality of voltage detection circuits 711 to 713. The voltage detection circuits 711 to 713 include pairs of rectifying elements (Dc and Dd, De and Df, Dg and Dh) with anodes and cathodes reversed and arranged in parallel, and detection circuits CP1 to CP3 that detect the voltage generated at one end of the pairs of rectifying elements. With this configuration, even when the amount of current generated by the energy conversion element 31 changes, the generated electric power can be efficiently output to the outside by the power supply circuit 80b.

[0164] In the above, various embodiments and variations have been described, but the present invention is not limited to these. 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.

[0165] The disclosure of the following priority basis application is incorporated herein by reference.

[0166] Japanese Patent Application No. 2019-116310 (filed on June 24, 2019)

[0167] Description of Reference Numerals

[0168] 1, 1a, 1b... ambient power generation device, 10, 10a... vibration power generation unit, 80, 80a, 80b... power supply circuit, 31... energy conversion element, 32... ambient sensor, 40, 40a... voltage limiting circuit, 50... rectifier circuit, 60... voltage conversion circuit, 70... current-voltage conversion circuit, M1 to M4... switching element, T1 to T8... control element (MOSFET), 41... dynamic comparator, 42... storage circuit, Ta to Tl... MOSFET, CP1 to CP3... voltage detection circuit, Da to Dg... rectifying element (diode), C1... first capacitor, C2... second capacitor, RO... external load.

Claims

1. An environmental power generation device, characterized in that, Comprising: An energy conversion element that converts the energy of the environment into electric power; An environmental sensor configured in the same environment as the energy conversion element; A power supply circuit that is input with the electric power converted by the energy conversion element and outputs the electric power to the outside, The power supply circuit changes its operation conditions corresponding to the output of the environmental sensor, The energy conversion element is an element that generates alternating current power, The power supply circuit has: a rectifying circuit that rectifies the alternating current power converted by the energy conversion element, The rectifying circuit has: a switching element that changes the connection conditions of the circuit corresponding to the output of the environmental sensor, The environmental sensor outputs an alternating current signal having the same frequency as the alternating current power converted by the energy conversion element, The power supply circuit has: a voltage limiting circuit that limits the alternating current signal output by the environmental sensor to a voltage within a specified range.

2. The environmental power generation device according to claim 1, characterized in that, The power supply circuit changes the operation conditions corresponding to the real-time output from the environmental sensor.

3. The environmental power generation device according to claim 1, characterized in that, The voltage limiting circuit includes a diode bridge circuit composed of MOSFETs.

4. The environmental power generation device according to claim 1, characterized in that, The voltage limiting circuit includes: A dynamic comparator that is input with the alternating current signal output by the environmental sensor; A storage circuit that stores the output of the dynamic comparator.

5. The environmental power generation device according to claim 4, characterized in that, The voltage limiting circuit has, on the input side of the dynamic comparator, two rectifying elements with anodes and cathodes reversed and connected in parallel.

6. The environmental power generation device according to claim 1 or 2, characterized in that, The power supply circuit has: a current-voltage conversion circuit that outputs a voltage signal corresponding to the amount of current output by the environmental sensor, The power supply circuit changes its operation conditions based on the output voltage from the current-voltage conversion circuit.

7. The environmental power generation device according to claim 6, characterized in that, The current-voltage conversion circuit includes a circuit in which a plurality of voltage detection circuits are connected in series, and the power supply circuit changes its operation conditions based on the detection signals from the plurality of voltage detection circuits, The voltage detection circuit includes a pair of rectifying elements with anodes and cathodes reversed and connected in parallel, and a detection circuit that detects the voltage at one end of the pair of rectifying elements.

8. The environmental power generation device according to any one of claims 1 to 5, characterized in that, The energy conversion element and the environmental sensor are vibration power generation elements.

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