Power supply device

Abstract

The degree of freedom in setting the discharge time can be improved while ensuring the stable operation of the load.SOLUTION: A power supply device according to an embodiment includes a power generation unit, a first capacitor charged by the power generation unit, a power supply unit capable of turning on and off power supply from the first capacitor to a drive circuit, a second capacitor charged from the first capacitor via a charging unit and having a smaller capacitance than the first capacitor, a discharge unit capable of turning on and off discharge from the second capacitor, and a voltage detection unit in which a first threshold voltage and a second threshold voltage lower than the first threshold voltage by hysteresis are set. The voltage detection means turns on the power supply means and the discharge means when the voltage of the second capacitor exceeds a first threshold voltage, and turns off the power supply means and the discharge means when the voltage of the second capacitor falls below a second threshold voltage.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The disclosed embodiments relate to a power supply device. [Background technology]

[0002] There are electronic devices that use solar cells as a power source. For example, if such electronic devices are applied to a remote control device for a toilet, they can be installed in many locations with minimal construction work, since no power supply work or battery replacement is required. However, the indoor lighting in a toilet is dimmer than other living spaces, and when the toilet is not in use, the lights may be turned off, creating complete darkness. Therefore, remote control devices and the like must be designed to accommodate the conditions that the solar cell output is small and may frequently drop to zero.

[0003] In toilets, there is a demand for contactless operation that allows the toilet to be flushed simply by waving a hand over a remote control. However, if a human body sensor such as a photoelectric sensor is used to detect the hand-waving operation, it is difficult to operate it continuously with the small output of a solar cell, so it is necessary to control the human body sensor to operate intermittently to reduce power consumption.

[0004] For example, if the human body sensor is operated at a cycle of 1 second, i.e., 1 Hz, it will detect the hand gesture with a maximum delay of 1 second. To improve the response of the human body sensor, it is better to have as high an intermittent drive frequency as possible, but this will increase power consumption accordingly, so it is desirable to operate at the fastest frequency possible according to the output of the solar cell.

[0005] There is a proposal to use a solar cell to charge a capacitor that serves as a circuit power source, and when the capacitor is charged to a predetermined voltage, current is passed through a load, and when the capacitor discharges as a result of the load current passing, the load current passing is terminated, and charging and current passing are repeated (see, for example, Patent Document 1). With this proposal, it is possible to intermittently pass current to the load at the fastest frequency in the solar cell output when repeating the load current passing.

[0006] Furthermore, there is a proposal to use a comparator with hysteresis as a voltage detection means for supplying energy from a capacitor connected in parallel with a solar cell to a secondary battery (see, for example, Patent Document 2). In this proposal, power supply to the secondary battery begins when the capacitor voltage reaches a predetermined voltage, and stops when the capacitor voltage drops by the amount of hysteresis. As a result, the amount of energy supplied at one time is determined as the voltage drop of the capacitor voltage by the amount of hysteresis. In this proposal, the voltage drop is charged using the output of the solar cell, and power supply and charging are repeated to intermittently energize the load, so energy is supplied intermittently at the fastest frequency according to the output of the solar cell.

[0007] Voltage detection means with hysteresis are generally known as "reset ICs" or "voltage monitoring ICs," and are widely available as general-purpose components that are highly accurate and low power consumption, and can be purchased inexpensively. In particular, they are integrated into circuits with extremely low power consumption, and some operate at less than 1 μA, so the use of reset ICs can be considered essential for applications that use solar cells. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 9-101754 [Patent Document 2] Japanese Patent Application Publication No. 7-250438 Summary of the Invention [Problem to be solved by the invention]

[0009] In the proposal in Reference 2, if charging of the secondary battery is replaced by powering the human body sensor, power will be supplied to the human body sensor intermittently at the fastest frequency according to the output of the solar cell, i.e., the illuminance, and the fastest response speed can be expected.

[0010] However, the amount of current flowing in one intermittent drive is determined by "capacitor capacity x hysteresis voltage." If the amount of current flowing in one time is large, it will take longer for the solar cell to charge the capacitor, which will lengthen the intermittent drive cycle and slow down the response of the human body sensor. Therefore, it is desirable to set the amount of current flowing in one time to the minimum amount of energy that allows the human body sensor to complete one detection.

[0011] The capacitor connected in parallel with the solar cell, which is one of the elements that determines the amount of current flowing per cycle, is a power source that supplies operating energy to the load. For example, in the case of the remote control device that flushes the toilet mentioned above, this load would first be the human body sensor, but would also include the load of the means for transmitting the toilet flush signal (radio waves or infrared rays). Therefore, regardless of the load current flow, even if the capacitor voltage drops, it is necessary to maintain a voltage that allows the load to operate, and since there is a minimum capacitance value, it cannot be made smaller than this value.

[0012] The hysteresis voltage of the voltage detection means, which is another factor that determines the amount of current flowing at one time, is the hysteresis voltage of the reset IC, and there is no other way to achieve this than to use a reset IC, especially from the perspective of low power consumption.The hysteresis voltage is a voltage range that prevents malfunction (chattering due to noise voltage) of the general-purpose component called the reset IC, and since it is determined by the component, there is no room for choice.

[0013] For the reasons mentioned above, if the capacitor capacity is increased to ensure the operation of the load, the amount of current flowing to the human body sensor per charge (discharge time) increases, which in turn lengthens the time it takes for the solar cell to charge the capacitor, lengthening the intermittent drive cycle of the human body sensor and slowing its response.Therefore, there was a need for a power supply device that could increase the flexibility in setting the discharge time while ensuring stable operation of the load.

[0014] One aspect of the embodiment has been made in view of the above, and aims to provide a power supply device that can improve the degree of freedom in setting the discharge time while ensuring stable operation of the load. [Means for solving the problem]

[0015] A power supply device according to one aspect of the embodiment includes a power generation means, a first capacitor charged by the power generation means, a power supply means capable of turning on and off the power supply from the first capacitor to a drive circuit, a second capacitor charged from the first capacitor via a charging means and having a smaller capacity than the first capacitor, a discharge means capable of turning on and off the discharge from the second capacitor, and a voltage detection means having a first threshold voltage and a second threshold voltage that is lower than the first threshold voltage by a hysteresis amount, wherein the voltage detection means turns on the power supply means and the discharge means when the voltage of the second capacitor exceeds the first threshold voltage, and turns off the power supply means and the discharge means when the voltage of the second capacitor falls below the second threshold voltage.

[0016] The amount of current flowing in one intermittent drive is determined by "capacitor capacity x hysteresis voltage." On the other hand, the capacitor connected to the power generation means must maintain a voltage that allows the load to operate even if the capacitor voltage drops when the load is energized, and there is a minimum capacitance value that cannot be made smaller.

[0017] Furthermore, the hysteresis voltage has no choice but to use a reset IC, especially from the perspective of low power consumption, and is a voltage to prevent malfunctions of general-purpose components (chattering due to noise voltage), so there is little freedom in selection (effectively no room for choice). Therefore, if you want to change the amount of current flowing per intermittent drive, you need to adjust the capacitor capacity, but even if you set the capacity value to the minimum, it will take longer to charge the capacitor using the power generation means, which could lengthen the intermittent drive cycle of the human body sensor and slow down its response.

[0018] With the configuration of the present invention, the amount of current flowing from the first capacitor to the drive circuit at one time is determined by (proportional to) the discharge time of the second capacitor, so there are no design constraints on the capacitance of the first capacitor, which increases the flexibility in setting the discharge time while ensuring stable operation of the load.

[0019] The charging means is a resistor connection.

[0020] This allows easy adjustment in accordance with the discharge capacity (resistance value) of the discharge means.

[0021] The charging means can turn on and off the charging from the first capacitor to the second capacitor, and turns off when the voltage of the second capacitor exceeds the first threshold voltage, and turns on when the voltage of the second capacitor falls below the second threshold voltage.

[0022] Since the first capacitor does not interfere with the discharge of the second capacitor, the discharge time can be easily adjusted.

[0023] The drive circuit is a sensor circuit capable of detecting a human body, and the first threshold voltage is greater than a minimum voltage at which the sensor circuit can operate.

[0024] This makes it possible to simultaneously achieve intermittent driving of the sensor circuit and ensure its operation.

[0025] The voltage detection means outputs a first signal when the voltage of the second capacitor exceeds the first threshold voltage, and outputs a second signal when the voltage of the second capacitor falls below the second threshold voltage. The voltage detection means includes delay signal output means for outputting a third signal that starts outputting after a predetermined delay time has elapsed since the output of the first signal of the voltage detection means and ends outputting simultaneously with the output of the second signal. Discharge acceleration means is provided in parallel with the discharge means, and the discharge acceleration means is activated by the third signal after the predetermined delay time has elapsed, thereby increasing the amount of discharge from the second capacitor.

[0026] By increasing the discharge amount after a specified delay time has elapsed since the start of discharge of the second capacitor, the discharge operation is a combination of the first stage (before the delay time) and the subsequent second stage (after the delay time). The first stage is a stage in which the discharge is slow to ensure the completion of load operation. The second stage is a stage in which the discharge is fast to reduce waste. This makes it possible to guarantee the sensor operation time and reduce waste.

[0027] The predetermined delay time is set to be longer than the time from when the drive circuit starts to be energized to when the drive circuit completes its operation.

[0028] The discharge time varies greatly due to variations in the hysteresis voltage and capacitor capacity. In contrast, a typical timer can be easily set, allowing you to set the time according to the operation of the load's sensor circuit.

[0029] The discharge acceleration means is a resistor.

[0030] The power supply can easily accelerate the discharge.

[0031] The discharge acceleration means is a circuit that connects a third capacitor in parallel with the second capacitor.

[0032] The voltage of the voltage detection means is the capacitance of the third capacitor added to that of the second capacitor, so the voltage of the second capacitor drops at the inverse of the rate of increase in capacitance (Q = C × V, i.e., charge = capacitance × voltage). Therefore, the power supply device can instantaneously lower the voltage applied to the voltage detection means. [Effects of the Invention]

[0033] According to one aspect of the embodiment, it is possible to improve the degree of freedom in setting the discharge time while ensuring stable operation of the load. [Brief explanation of the drawings]

[0034] [Figure 1]FIG. 1 is a diagram showing the circuit configuration of a power supply device according to the first embodiment. [Figure 2] FIG. 2 is a timing chart showing the operation of the power supply device according to the first embodiment. [Figure 3] FIG. 3 is a diagram showing a circuit configuration of a power supply device according to the second embodiment. [Figure 4] FIG. 4 is a diagram showing a circuit configuration of a power supply device according to the third embodiment. [Figure 5] FIG. 5 is a timing chart showing the operation of the power supply device according to the third embodiment. [Figure 6] FIG. 6 is a diagram showing a circuit configuration of a power supply device according to the fourth embodiment. [Figure 7] FIG. 7 is a timing chart showing the operation of the power supply device according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0035] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the power supply device disclosed in the present application will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0036] The circuit configuration of a power supply device 1 according to a first embodiment of the present invention will be described below with reference to Fig. 1. Fig. 1 is a diagram showing the circuit configuration of a power supply device 1 according to the first embodiment.

[0037] 1, the power supply device 1 includes a power generating means 2, a first capacitor 3, a power supplying means 4, a second capacitor 5, a discharging means 6, and a voltage detecting means 7. The power supply device 1 is provided in, for example, a remote control device for a toilet.

[0038] The power generating means 2 is, for example, a solar cell. The power generating means 2 generates power by utilizing light such as lighting in the toilet room or external light. The power generating means 2 supplies the generated power to the first capacitor 3.

[0039] The first capacitor 3 is charged by the power generation means 2. The first capacitor 3 is connected in parallel with the power generation means 2. The first capacitor 3 supplies the charged power to the drive circuit 8.

[0040] The power supply unit 4 can turn on and off the power supply from the first capacitor 3 to the drive circuit 8. The power supply unit 4 is connected to the first capacitor 3 and the drive circuit 8. The power supply unit 4 is, for example, a switch, and can switch the energized state of the drive circuit 8 by switching the switch on and off. Specifically, the power supply unit 4 starts the operation of the drive circuit 8 by turning on the power supply from the first capacitor 3 to the drive circuit 8. The power supply unit 4 stops the operation of the drive circuit 8 by turning off the power supply from the first capacitor 3 to the drive circuit 8.

[0041] The second capacitor 5 is charged from the first capacitor 3 via a charging means 9. Here, the charging means 9 in this embodiment is a resistive connection 9a. The second capacitor 5 is connected in parallel to the first capacitor 3 via the charging means 9. The second capacitor 5 has a smaller capacitance than the first capacitor 3.

[0042] The discharge means 6 can turn on and off the discharge from the second capacitor 5. The discharge means 6 is connected in parallel with the second capacitor 5. The discharge means 6 has, for example, a switch 6a and a resistor 6b, and can switch the discharge state of the second capacitor 5 by switching the switch 6a on and off. Specifically, the discharge means 6 can turn on the discharge from the second capacitor 5 by turning on the switch 6a. The discharge means 6 can turn off the discharge from the second capacitor 5 by turning off the switch 6a.

[0043] The voltage detection means 7 detects the voltage of the second capacitor 5. The voltage detection means 7 is, for example, a reset IC, and is set with a first threshold voltage Va and a second threshold voltage Vb, which is lower than the first threshold voltage Va by hysteresis H, as shown in FIG. 2 . The voltage detection means 7 is connected to the power supply means 4 and the discharge means 6 and is capable of outputting a first signal that turns on the power supply means 4 and the discharge means 6. The voltage detection means 7 is also capable of outputting a second signal that turns off the power supply means 4 and the discharge means 6. When the voltage of the second capacitor 5 exceeds the first threshold voltage Va, the voltage detection means 7 outputs the first signal to the power supply means 4 and the discharge means 6. When the voltage of the second capacitor 5 falls below the second threshold voltage Vb, the voltage detection means 7 outputs the second signal to the power supply means 4 and the discharge means 6.

[0044] The drive circuit 8 is a sensor circuit capable of detecting a human body. The drive circuit 8 includes a remote control signal transmission means that operates using the sensor circuit as a trigger. The first threshold voltage Va is greater than the minimum voltage at which the sensor circuit can operate. Furthermore, when this embodiment is applied to a toilet flush remote control, the drive circuit 8 also has the function of transmitting a remote control signal to flush the toilet when a human body is detected.

[0045] Next, the operation of the power supply device 1 according to the first embodiment will be described with reference to Fig. 2. Fig. 2 is a timing chart showing the operation of the power supply device 1 according to the first embodiment. Note that the graph in Fig. 2 shows the voltage V1 of the first capacitor 3 and the voltage V2 of the second capacitor 5. Similarly, Figs. 5 and 7, which will be described later, also show the voltage V1 of the first capacitor 3 and the voltage V2 of the second capacitor 5.

[0046] 2, when the voltage V2 of the second capacitor 5 exceeds the first threshold voltage Va, the voltage detection means 7 outputs a first signal (turns on the reset IC output), turns on the power supply from the first capacitor 3 to the drive circuit 8, and turns on the discharge from the second capacitor 5. When the power supply from the first capacitor 3 to the drive circuit 8 is turned on, the power of the drive circuit 8 (sensor circuit) is turned on. Then, for example, a light projection pulse is projected from a photoelectric sensor included in the drive circuit 8 for a certain period of time.

[0047] When the voltage V2 of the second capacitor 5 falls below the second threshold voltage Vb, the voltage detection means 7 outputs a second signal (turns off the reset IC output) to turn off the power supply from the first capacitor 3 to the drive circuit 8 and turn off the discharge from the second capacitor 5. Note that the time from when the projection of the light projection pulse ends until the discharge means 6 turns off the discharge of the second capacitor 5 is a margin time that guarantees the operating time of the drive circuit 8 (see arrow A).

[0048] 2, when the output of the voltage detection means 7 is at Hi level it is the first signal, and when it is at Lo level it is the second signal. In other words, these signals are signals that the voltage detection means 7 determines whether the voltage is high or low, so the first signal and the second signal are never output at the same time.

[0049] With the power supply device 1 configured as described above, the amount of current flowing from the first capacitor 3 to the drive circuit 8 (sensor circuit) at one time is determined by (proportional to) the discharge time of the second capacitor 5, so there are no design constraints on the capacitance of the first capacitor 3. Therefore, it is not the case that the capacitance of the first capacitor 3 cannot be increased in order to reduce power consumption, and the capacitance of the first capacitor 3 can be set to a large enough capacitance that allows the drive circuit 8 to operate stably.

[0050] Furthermore, the amount of current flowing to the drive circuit 8 is proportional to the current flow time, which is the discharge time of the second capacitor 5, and can be adjusted by the voltage of the hysteresis H, the capacitance of the second capacitor 5, and the discharge capacity (value of the discharge resistor) of the discharge means 6. Therefore, the degree of freedom in setting the discharge time can be improved.

[0051] Furthermore, since the charging means 9 is a resistance connection 9a, it is inexpensive, and the resistance value of the charging means 9 can be set in accordance with the capacity (resistance value) of the discharging means 6.

[0052] Furthermore, by using an appropriate voltage detection means 7, it is possible to simultaneously achieve intermittent operation and guaranteed operation of the drive circuit 8. Note that it is possible to arbitrarily set the charge / discharge voltage of the second capacitor 5, but in that case, a separate voltage detection means is required to guarantee the operation of the drive circuit 8 (sensor circuit).

[0053] Next, a second embodiment of the present invention will be described in detail with reference to Fig. 3. Fig. 3 is a diagram showing the circuit configuration of a power supply device 1 according to the second embodiment. The following description will focus on processes that are different from those in the first embodiment, and will omit a description of processes that are the same as those in the first embodiment.

[0054] As shown in FIG. 3, the charging means 9 in this embodiment is a switch 9b.

[0055] The charging means 9 can turn on and off the charging of the second capacitor 5 from the first capacitor 3. The charging means 9 turns off when the voltage V2 of the second capacitor 5 exceeds a first threshold voltage Va (see FIG. 2), and turns on when the voltage V2 of the second capacitor 5 falls below a second threshold voltage Vb (see FIG. 2). Note that charging of the second capacitor 5 is not limited to charging by the first capacitor 3, and when the first capacitor 3 is being charged by the power generation means 2, it can be considered that the second capacitor 5 is also being charged by the power generation means 2.

[0056] The charging means 9 can switch the charging state of the second capacitor 5, for example, by switching on and off the switch 9b. Specifically, the charging means 9 can turn on charging of the second capacitor 5 by turning on the switch 9b. The charging means 9 can turn off charging of the second capacitor 5 by turning off the switch 9b.

[0057] The voltage detection means 7 is connected to the power supply means 4, the discharge means 6, and the charging means 9, and is capable of outputting a first signal that turns on the power supply means 4 and the discharge means 6 and turns off the charging means 9. The voltage detection means 7 is also capable of outputting a second signal that turns off the power supply means 4 and the discharge means 6 and turns on the charging means 9. When the voltage V2 of the second capacitor 5 exceeds a first threshold voltage Va, the voltage detection means 7 outputs the first signal to the power supply means 4, the discharge means 6, and the charging means 9. When the voltage V2 of the second capacitor 5 falls below a second threshold voltage Vb, the voltage detection means 7 outputs a second signal to the power supply means 4, the discharge means 6, and the charging means 9.

[0058] According to the power supply device 1 configured as above, by turning off the switch 9b, the charging of the second capacitor 5 stops and only the discharging operation by the discharging means 6 takes place, which makes it easy to set the discharge time.

[0059] Next, a third embodiment of the present invention will be described with reference to Fig. 4. Fig. 4 is a diagram showing the circuit configuration of a power supply device 1 according to the third embodiment.

[0060] As shown in FIG. 4, the power supply device 1 includes a delay signal output means 10 and a discharge acceleration means 11.

[0061] The delay signal output means 10 is connected to the voltage detection means 7 and the discharge acceleration means 11, and is capable of outputting a third signal that is a signal that turns on the discharge acceleration means 11. The delay signal output means 10 starts outputting the third signal after a predetermined delay time has elapsed since the voltage detection means 7 outputted the first signal, and ends outputting the third signal simultaneously with outputting the second signal.

[0062] The discharge acceleration means 11 can turn on and off the discharge from the second capacitor 5 in the discharge acceleration means 11 when the switch 6a of the discharge means 6 is on. The discharge acceleration means 11 is connected in parallel with the discharge means 6. The discharge acceleration means 11 has, for example, a switch 11a and a resistor 11b, and can switch the discharge state of the second capacitor 5 by switching the switch 11a on and off. Specifically, the discharge acceleration means 11 can turn on the discharge from the second capacitor 5 in the discharge acceleration means 11 by turning on the switch 11a. The discharge acceleration means 11 can turn off the discharge from the second capacitor 5 in the discharge acceleration means 11 by turning off the switch 11a.

[0063] Next, the operation of the power supply device 1 according to the third embodiment will be described with reference to Fig. 5. Fig. 5 is a timing chart showing the operation of the power supply device 1 according to the third embodiment.

[0064] As shown in FIG. 5, when a predetermined delay time (see arrow B) has elapsed since the voltage detection means 7 output the first signal, the delay signal output means 10 starts outputting the third signal. Then, the discharge acceleration means 11 increases the discharge amount of the second capacitor 5 for the time indicated by arrow C until the delay signal output means 10 finishes outputting the third signal. In this way, the discharge acceleration means 11 reliably reduces the voltage of the second capacitor 5 to a voltage below the second threshold voltage Vb in a short time. The predetermined delay time is the guaranteed operation time of the drive circuit 8 and is set longer than the time from the start of energization of the drive circuit 8 to the completion of operation. For example, the operation of the drive circuit 8 is an operation in which a photoelectric sensor emits a light projection pulse to detect a body.

[0065] With the power supply device 1 configured as described above, the discharge amount of the second capacitor 5 is increased after a predetermined delay time has elapsed since the start of discharge of the second capacitor 5, so that the discharge operation is a combination of an initial first stage (before the delay time) and a subsequent second stage (after the delay time). The first stage is a stage in which slow discharge is performed to ensure the completion of load operation. The second stage is a stage in which fast discharge is performed to reduce waste. This makes it possible to guarantee the sensor operation time and reduce waste.

[0066] Next, a fourth embodiment of the present invention will be described in detail with reference to the drawings. Fig. 6 is a diagram showing the circuit configuration of a power supply device 1 according to the fourth embodiment. Fig. 7 is a timing chart showing the operation of the power supply device 1 according to the fourth embodiment.

[0067] As shown in FIG. 6, the discharge acceleration means 11 includes a switch 11a, a third capacitor 11c, and a resistor 11d. The discharge acceleration means 11 is a circuit that connects the third capacitor 11c in parallel with the second capacitor 5. The discharge acceleration means 11 is configured to discharge the third capacitor 11c in advance (before connecting it in parallel with the second capacitor 5) using the resistor 11d. The discharge acceleration means 11 is also configured such that the third capacitor 11c is provided in parallel with the second capacitor 5, and the voltage drops by the amount of increase in capacitance due to the third capacitor 11c. Electrically speaking, the relationship is "Q = C × V," i.e., "charge = capacitance × voltage," so that "voltage = charge / capacitance." Because the charge does not change instantaneously, the voltage drops inversely with respect to an increase in capacitance.

[0068] Next, the operation of the power supply device 1 according to the fourth embodiment will be described with reference to Fig. 7. Fig. 7 is a timing chart showing the operation of the power supply device 1 according to the fourth embodiment.

[0069] 7, when a predetermined delay time (see arrow D) has elapsed since the output of the first signal from the voltage detection means 7, the delay signal output means 10 starts outputting the third signal. Then, the discharge acceleration means 11 continues discharging by the discharge means 6 in addition to reducing the voltage by connecting the third capacitor 11c in parallel for only the time indicated by arrow E until the delay signal output means 10 finishes outputting the third signal. In this way, the discharge acceleration means 11 reliably reduces the voltage of the second capacitor 5 to a voltage below the second threshold voltage Vb in a short period of time.

[0070] According to the power supply device 1 configured as above, the voltage applied to the voltage detection means 7 can be instantaneously reduced by connecting the second capacitor 5 and the third capacitor 11c in parallel.

[0071] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

[0072] <Additional Notes> (1) A power generation means; a first capacitor charged by the power generation means; a power supply means capable of turning on and off the power supply from the first capacitor to the drive circuit; a second capacitor that is charged by the first capacitor via a charging means and has a smaller capacitance than the first capacitor; a discharge means capable of turning on and off discharge from the second capacitor; a voltage detection means in which a first threshold voltage and a second threshold voltage that is lower than the first threshold voltage by a hysteresis are set; The voltage detection means turns on the power supply means and the discharge means when the voltage of the second capacitor exceeds the first threshold voltage, and turns off the power supply means and the discharge means when the voltage of the second capacitor falls below the second threshold voltage. (2) The power supply device according to (1), wherein the charging means is a resistance connection. (3) The power supply device according to (1), wherein the charging means is capable of turning on and off charging from the first capacitor to the second capacitor, turning off the charging when the voltage of the second capacitor exceeds the first threshold voltage, and turning on the charging when the voltage of the second capacitor falls below the second threshold voltage. (4) the drive circuit is a sensor circuit capable of detecting a human body, The power supply device according to any one of (1) to (3), wherein the first threshold voltage is higher than a minimum voltage at which the sensor circuit can operate. (5) the voltage detection means outputs a first signal when the voltage of the second capacitor exceeds the first threshold voltage, and outputs a second signal when the voltage of the second capacitor falls below the second threshold voltage, a delay signal output means for outputting a third signal, the third signal being output after a predetermined delay time has elapsed since the output of the first signal of the voltage detection means, and ending its output simultaneously with the output of the second signal; a discharge acceleration means is provided in parallel with the discharge means, The power supply device according to any one of (1) to (4), wherein the discharge acceleration means is activated by the third signal after the predetermined delay time has elapsed, thereby increasing the amount of discharge of the second capacitor. (6) The power supply device according to (5), wherein the predetermined delay time is set to be longer than the time from when the power supply to the drive circuit starts to when the operation is completed. (7) The power supply device according to (6), wherein the discharge acceleration means is a resistor. (8) The power supply device according to (6), wherein the discharge acceleration means is a circuit that connects a third capacitor in parallel with the second capacitor. [Explanation of symbols]

[0073] 1 Power supply 2. Means of power generation 3 First Capacitor 4 Power supply means 5 Second Capacitor 6 Discharge means 7. Voltage detection means 8 Drive circuit 9 Charging means 9a Resistor connection 10 Delay signal output means 11 Discharge acceleration means V2 Voltage of the second capacitor Va First threshold voltage Vb Second threshold voltage

Claims

1. A power generation means; a first capacitor charged by the power generating means; a power supply means capable of turning on and off the power supply from the first capacitor to the drive circuit; a second capacitor that is charged by the first capacitor via a charging means and has a smaller capacitance than the first capacitor; a discharge means capable of turning on and off discharge from the second capacitor; a voltage detection means in which a first threshold voltage and a second threshold voltage that is lower than the first threshold voltage by a hysteresis are set; The voltage detection means turns on the power supply means and the discharge means when the voltage of the second capacitor exceeds the first threshold voltage, and turns off the power supply means and the discharge means when the voltage of the second capacitor falls below the second threshold voltage.

2. 2. The power supply device according to claim 1, wherein said charging means is a resistor connection.

3. 2. The power supply device according to claim 1, wherein the charging means is capable of turning on and off charging from the first capacitor to the second capacitor, turning off the charging when the voltage of the second capacitor exceeds the first threshold voltage, and turning on the charging when the voltage of the second capacitor falls below the second threshold voltage.

4. the drive circuit is a sensor circuit capable of detecting a human body, 2. The power supply device according to claim 1, wherein the first threshold voltage is greater than a minimum voltage at which the sensor circuit can operate.

5. the voltage detection means outputs a first signal when the voltage of the second capacitor exceeds the first threshold voltage, and outputs a second signal when the voltage of the second capacitor falls below the second threshold voltage, a delay signal output means for outputting a third signal, the third signal starting a predetermined delay time after the output of the first signal from the voltage detection means and ending its output simultaneously with the output of the second signal; a discharge acceleration means is provided in parallel with the discharge means, 2. The power supply device according to claim 1, wherein the discharge acceleration means is activated by the third signal after the predetermined delay time has elapsed, thereby increasing the amount of discharge from the second capacitor.

6. 6. The power supply device according to claim 5, wherein the predetermined delay time is set to be longer than the time from when the power supply to the drive circuit starts to be turned on until the operation is completed.

7. 7. The power supply device according to claim 5, wherein the discharge acceleration means is a resistor.

8. 7. The power supply device according to claim 5, wherein the discharge acceleration means is a circuit that connects a third capacitor in parallel with the second capacitor in response to a third signal.

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