Power circuit and toilet equipment

Abstract

To provide a toilet device and a power supply circuit for the toilet device that can suppress an output voltage of a step-down circuit from becoming lower than a desired voltage while suppressing an increase in power consumption even when a control element having a feedback function is used in the step-down circuit.SOLUTION: A power supply circuit for a toilet device includes a rectifier circuit that rectifies AC power supplied from a commercial power source to convert the AC power into rectified power, an input capacitor that converts the rectified power into DC power, and a step-down circuit that converts first DC power supplied from the input capacitor into second DC power having a lower voltage than the first DC power and supplies the second DC power to a drive circuit. The step-down circuit includes a pair of input terminals, a pair of output terminals, a control element, an inductor, a first rectifier, a second rectifier, an output capacitor, and a control element capacitor. The reverse recovery time of the first rectifier is shorter than the reverse recovery time of the second rectifier.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Aspects of the present invention generally relate to a power supply circuit and a toilet device.

Background Art

[0002] There is a toilet device including a toilet main body, a pump for supplying washing water to the toilet main body, a drive circuit for switching the drive and stop of the pump, and a power supply circuit for supplying power to the drive circuit. The power supply circuit converts alternating current power supplied from a commercial power supply into direct current power corresponding to the drive circuit and supplies the converted direct current power to the drive circuit. The power supply circuit has a step-down circuit and supplies the stepped-down direct current power to the drive circuit. The drive circuit operates by the supply of direct current power from the power supply circuit.

[0003] In such a toilet device, attempts have been made to make the functional parts such as toilet washing as small as possible to improve the design. For example, it is required to adopt a low-silhouette design in which the height of the functional parts arranged behind the toilet main body is made as low as possible.

[0004] Therefore, miniaturization is also required for the power supply circuit. In the power supply circuit, in order to meet the requirement of miniaturization, it has been proposed to use a control element incorporating a switching element and a control circuit for controlling the switching of the switching element in the step-down circuit. The control element is, in other words, a power supply IC (Integrated Circuit). In the step-down circuit using the control element, since various circuit elements are integrated in the control element, the number of parts of the step-down circuit can be reduced and the power supply circuit can be miniaturized compared with the case where the switching element, the control circuit, etc. are individually mounted.

[0005] The control element has a feedback function, detects the output voltage, and controls the switching of the switching element so that the output voltage becomes a predetermined voltage set in advance. Thereby, while miniaturizing the power supply circuit, it is possible to supply stable power.

[0006] However, as a result of diligent research, the inventors of this application have found that in a step-down circuit using a control element with a feedback function, the output voltage of the step-down circuit may fall below the desired voltage. When the output voltage of the step-down circuit drops, it can lead to instability in the operation of the drive circuit and the pump.

[0007] One possible method to stabilize the output voltage of a step-down circuit is to place a resistive element (a so-called bleeder resistor) in parallel with the load at the output terminal of the step-down circuit and adjust the resistance value of the resistive element. However, in this case, the power consumption of the power supply circuit may increase.

[0008] Therefore, in toilet equipment and the power supply circuits used therein, it is desirable to be able to suppress the increase in power consumption while also preventing the output voltage of the step-down circuit from falling below the desired voltage, even when a control element with a feedback function is used in the step-down circuit. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2022-95113 [Overview of the project] [Problems that the invention aims to solve]

[0010] The present invention was made based on the recognition of the above problems, and aims to provide a power supply circuit for a toilet device, and a toilet device using the same, that can suppress the increase in power consumption and prevent the output voltage of the step-down circuit from falling below the desired voltage, even when a control element with a feedback function is used in the step-down circuit. [Means for solving the problem]

[0011] The first invention relates to a toilet system comprising a toilet bowl body, a pump for supplying flushing water to the toilet bowl body, and a drive circuit for switching the operation and stopping of the pump, and is a power supply circuit for supplying power to the drive circuit, comprising: a rectifier circuit that converts AC power supplied from a commercial power source into rectified power by rectifying the AC power; an input capacitor that converts the rectified power into DC power by smoothing the rectified power; and a step-down circuit that converts the first DC power supplied from the input capacitor into a second DC power with a lower voltage than the first DC power, and supplies the second DC power to the drive circuit, wherein the step-down circuit comprises a pair of input terminals, a pair of output terminals, a control element, an inductor, a first rectifier element, a second rectifier element, an output capacitor, and a capacitor for the control element, wherein the pair of input terminals are connected to both ends of the input capacitor, the pair of output terminals are connected to the drive circuit, and the control element comprises a switching element and the switch The device comprises a control circuit for controlling the switching of a switching element and a package, the switching element and the control circuit are housed within the package, the switching element has a pair of main terminals and a control terminal, the package has a first terminal, a second terminal and a third terminal, one of the main terminals of the switching element is connected to the first terminal within the package, the other main terminal of the switching element is connected to the second terminal within the package, one end of the inductor is connected to the second terminal, the other end of the inductor is connected to the output terminal on the high potential side, the cathode of the first rectifier element is connected to the connection point between the second terminal and the one end of the inductor, the anode of the first rectifier element is connected to the output terminal on the low potential side, one end of the output capacitor is connected to the connection point between the other end of the inductor and the output terminal on the high potential side, the other end of the output capacitor is connected to the output terminal on the low potential side, and the second rectifier element anode It is connected to the connection point between the other end of the inductor and the output terminal on the high potential side, and the second rectifier element cathode It is connected to the third terminal, and one end of the capacitor for the control element is connected to the second rectifier element. cathodeA power supply circuit for a toilet device, characterized in that it is connected to the connection point between the second terminal and the third terminal, the other end of the capacitor for the control element is connected to the connection point between the second terminal and the one end of the inductor, the control circuit has a feedback function and performs feedback control of the switching of the switching element so that the voltage at the third terminal becomes a predetermined voltage, and the reverse recovery time of the first rectifier element is shorter than the reverse recovery time of the second rectifier element.

[0012] This power supply circuit ensures that the reverse recovery time of the first rectifier element is shorter than that of the second rectifier element. This primarily directs the current released from the inductor in a short time to the first rectifier element, suppressing the tendency for the voltage of the control element capacitor to rise more easily than the voltage of the output capacitor. As a result, it is possible to prevent the output voltage of the step-down circuit from falling below the desired voltage. Furthermore, compared to a method of stabilizing the output voltage of the step-down circuit by adjusting the resistance value of a resistor element connected in parallel with the load at the pair of output terminals of the step-down circuit, this method also suppresses an increase in the power consumption of the power supply circuit. Therefore, even when a control element with a feedback function is used in the step-down circuit, it is possible to suppress an increase in power consumption while preventing the output voltage of the step-down circuit from falling below the desired voltage.

[0013] The second invention is a power supply circuit for a toilet device, characterized in that, in the first invention, the capacitance of the control element capacitor is smaller than the capacitance of the output capacitor.

[0014] This power supply circuit makes the reverse recovery time of the first rectifier element shorter than that of the second rectifier element, thereby preventing the output voltage of the step-down circuit from falling below the desired voltage while also preventing the capacitance of the control element capacitor from becoming unnecessarily large.

[0015] The third invention is a power supply circuit for a toilet device, characterized in that, in the first invention, the reverse recovery time of the first rectifier element is 10 ns or more and 100 ns or less, and the reverse recovery time of the second rectifier element is 2 μs or more and 10 μs or less.

[0016] This power supply circuit allows the current discharged from the inductor in a short period of time to flow more appropriately to the first rectifier element, and more effectively suppresses the tendency for the voltage of the control element capacitor to rise more easily than the voltage of the output capacitor. As a result, it is possible to more effectively suppress the output voltage of the step-down circuit from falling below the desired voltage.

[0017] The fourth invention is a power supply circuit for a toilet device, characterized in that, in the first invention, the reverse recovery time of the second rectifier element is 20 times or more the reverse recovery time of the first rectifier element.

[0018] This power supply circuit allows the current discharged from the inductor in a short period of time to flow more appropriately to the first rectifier element, and more effectively suppresses the tendency for the voltage of the control element capacitor to rise more easily than the voltage of the output capacitor. As a result, it is possible to more effectively suppress the output voltage of the step-down circuit from falling below the desired voltage.

[0019] The fifth invention comprises a toilet bowl body, a pump for supplying flushing water to the toilet bowl body, a drive circuit for switching the operation and stopping of the pump, and a power supply circuit for supplying power to the drive circuit, wherein the power supply circuit includes a rectifier circuit that converts AC power supplied from a commercial power source into rectified power by rectifying the AC power, an input capacitor that converts the rectified power into DC power by smoothing the rectified power, and a step-down circuit that converts the first DC power supplied from the input capacitor into a second DC power with a lower voltage than the first DC power, and supplies the second DC power to the drive circuit, wherein the step-down circuit includes a pair of input terminals, a pair of output terminals, a control element, an inductor, a first rectifier element, a second rectifier element, an output capacitor, and a capacitor for the control element, wherein the pair of input terminals are connected to both ends of the input capacitor, the pair of output terminals are connected to the drive circuit, and the control element includes a switching element and the switching element The switching element and the control circuit are housed within the package, the switching element has a pair of main terminals and a control terminal, the package has a first terminal, a second terminal and a third terminal, one of the main terminals of the switching element is connected to the first terminal within the package, the other main terminal of the switching element is connected to the second terminal within the package, one end of the inductor is connected to the second terminal, the other end of the inductor is connected to the output terminal on the high potential side, the cathode of the first rectifier element is connected to the connection point between the second terminal and the one end of the inductor, the anode of the first rectifier element is connected to the output terminal on the low potential side, one end of the output capacitor is connected to the connection point between the other end of the inductor and the output terminal on the high potential side, the other end of the output capacitor is connected to the output terminal on the low potential side, and the second rectifier element anode It is connected to the connection point between the other end of the inductor and the output terminal on the high potential side, and the second rectifier element cathode It is connected to the third terminal, and one end of the capacitor for the control element is connected to the second rectifier element. cathodeis connected to the connection point with the third terminal, the other end of the capacitor for the control element is connected to the connection point between the second terminal and the one end of the inductor, the control circuit has a feedback function, and the voltage of the third terminal is set to a predetermined voltage. The switching feedback control of the switching element is performed so that the reverse recovery time of the first rectifying element is shorter than the reverse recovery time of the second rectifying element. It is a toilet device characterized by that.

[0020] According to this toilet device, since the reverse recovery time of the first rectifying element is shorter than the reverse recovery time of the second rectifying element, the current discharged from the inductor in a short time mainly flows to the first rectifying element side, and the voltage of the capacitor for the control element is compared with the voltage of the output capacitor. It is possible to suppress the tendency to increase easily. As a result, it is possible to suppress the output voltage of the step-down circuit from becoming lower than the desired voltage. In addition, by adjusting the resistance value of the resistance element provided in parallel with the load at the pair of output terminals of the step-down circuit, it is possible to suppress an increase in the power consumption of the power supply circuit compared to the method of stabilizing the output voltage of the step-down circuit. Therefore, even when a control element having a feedback function is used in the step-down circuit, it is possible to suppress an increase in power consumption and suppress the output voltage of the step-down circuit from becoming lower than the desired voltage.

Effect of the Invention

[0021] According to an aspect of the present invention, there is provided a power supply circuit for a toilet device that can suppress an increase in power consumption and suppress the output voltage of a step-down circuit from becoming lower than a desired voltage even when a control element having a feedback function is used in the step-down circuit, and a toilet device using the same.

Brief Description of the Drawings

[0022] [Figure 1] It is an explanatory diagram schematically showing a toilet device according to an embodiment. [Figure 2] It is a block diagram schematically showing a power supply circuit according to an embodiment. [Figure 3]It is a block diagram schematically showing a step-down circuit according to an embodiment.

Mode for Carrying Out the Invention

[0023] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0024] FIG. 1 is an explanatory diagram schematically showing a toilet device according to an embodiment. As shown in FIG. 1, the toilet device 2 includes a toilet bowl main body 10 and a toilet bowl cleaning device 20. The toilet bowl main body 10 is placed, for example, on the floor surface of a toilet room. The toilet bowl main body 10 is, in other words, a Western-style sitting toilet. The toilet bowl cleaning device 20 supplies cleaning water to the toilet bowl main body 10. The toilet bowl cleaning device 20 is arranged, for example, behind the toilet bowl main body 10. The toilet bowl cleaning device 20 is attached, for example, behind the toilet bowl main body 10 and forms an integral form with the toilet bowl main body 10.

[0025] The toilet device 2 is, for example, a toilet in which functional parts such as the toilet bowl cleaning device 20 are provided integrally with the toilet bowl main body 10. The functional parts may further have, for example, a function of a heated toilet seat for warming the toilet seat and a function of hygienic cleaning for cleaning the local part of the user sitting on the toilet seat.

[0026] The toilet bowl main body 10 has a bowl part 11 for receiving dirt and a drain trap pipe 12 extending rearward from the bottom of the bowl part 11. The drain trap pipe 12 communicates with a sewage pipe (not shown). The drain trap pipe 12 forms a water seal and suppresses the intrusion of foul odors and pests from the sewage pipe.

[0027] The bowl part 11 has a rim water outlet 13 for performing rim water discharge and a jet water outlet 14 for performing jet water discharge. The rim water outlet 13 is provided, for example, at the upper rear of the bowl part 11 and discharges cleaning water along the upper edge of the bowl part 11.

[0028] The jet nozzle 14 is located at the bottom of the bowl section 11 and discharges cleaning water towards the drain trap pipe 12. By discharging cleaning water towards the drain trap pipe 12 and filling the drain trap pipe 12 with cleaning water, the jet nozzle 14 generates a siphon effect in the drain trap pipe 12. This makes it easier to discharge the water accumulated in the bowl section 11 into the sewer pipe when flushing the toilet to clean the inside of the bowl section 11.

[0029] The toilet flushing device 20 includes an operating unit 22, a control unit 24, a valve unit 26, a tank 28, a pump 30, a drive circuit 32, and a power supply circuit 100.

[0030] The control unit 22 includes a flush switch for starting toilet flushing. The control unit 22 is, for example, an operation panel. When the flush switch is operated by the user, the control unit 22 outputs a signal to the control unit 24 indicating the start of toilet flushing. The signal indicating the start of toilet flushing is not limited to the control unit 22; for example, it may be input to the control unit 24 from a sensor such as a seat detection sensor. Toilet flushing may also be started, for example, in response to the detection that the user has moved away from the toilet seat (toilet bowl 10).

[0031] The control unit 24 controls the operation of the valve unit 26, pump 30, etc., based on a signal indicating the start of toilet flushing output from the operation unit 22, for example. The control unit 24 is a controller that includes, for example, a microcomputer having a CPU (Central Processing Unit) and memory, and various control circuits.

[0032] The valve unit 26 is connected to a water supply channel 40 that supplies cleaning water from a water source (not shown). The valve unit 26 receives cleaning water from the water source via the water supply channel 40. The valve unit 26 is also connected to a rim-side water supply channel 42 for supplying cleaning water to the rim outlet 13, and a tank-side water supply channel 44 for supplying cleaning water to the tank 28.

[0033] The valve unit 26 includes, for example, a constant flow valve 50, a diaphragm-type water supply valve 51 located downstream of the constant flow valve 50, a vacuum breaker 52 located downstream of the water supply valve 51, and a switching valve 53 located downstream of the vacuum breaker 52.

[0034] The constant flow valve 50 controls the flow rate of the cleaning water so that the flow rate of the cleaning water flowing from the water supply channel 40 into the constant flow valve 50 and moving downstream is substantially constant. The water supply valve 51 has, for example, a diaphragm, and by opening and closing the diaphragm, it switches between discharging and shutting off the cleaning water at the rim outlet 13 and the jet outlet 14.

[0035] The vacuum breaker 52 suppresses the backflow of cleaning water caused by negative pressure in the water supply channel 40. The cleaning water that overflows from the vacuum breaker 52 is collected by the water receiving section 54 and then discharged into the tank 28 through the drainage channel 46 connected to the bottom of the water receiving section 54.

[0036] The switching valve 53 switches the destination of the flushing water supply from the water source between the rim outlet 13 of the toilet bowl body 10 and the tank 28. In other words, the switching valve 53 supplies flushing water to either the rim-side water supply channel 42 or the tank-side water supply channel 44.

[0037] Tank 28 stores flushing water supplied to the jet outlet 14 of the toilet bowl body 10. Tank 28 stores flushing water supplied from valve unit 26 (water supply channel 40) via tank-side water supply channel 44. Tank 28 is connected to a water supply pipe 60. One end of the water supply pipe 60 is located, for example, at the bottom of the tank 28 inside the tank 28. The other end of the water supply pipe 60 is connected to a pump 30.

[0038] Pump 30 supplies flushing water to the toilet bowl body 10. More specifically, pump 30 is a pump that supplies flushing water into the bowl portion 11 of the toilet bowl body 10 for flushing the inside of the bowl portion 11.

[0039] The pump 30 is connected to the tank 28 via a water supply pipe 60 and to the jet outlet 14 of the toilet bowl body 10 via a water supply pipe 62. The pump 30 pressurizes the flushing water stored in the tank 28 and supplies it to the jet outlet 14 (toilet bowl body 10) via the water supply pipe 62. As a result, flushing water is discharged from the jet outlet 14 towards the drain trap pipe 12, as described above.

[0040] Pump 30 can be any type of pump, such as a centrifugal pump, a diffuser pump, or a cascade pump. Pump 30 has, for example, a motor (not shown), and supplies flushing water by the rotation of the motor. However, pump 30 is not limited to the above, and can be any pump capable of properly supplying flushing water to the toilet bowl body 10.

[0041] The drive circuit 32 switches between driving and stopping the pump 30 based on the control signal input from the control unit 24.

[0042] The power supply circuit 100 is connected to the commercial power supply PS via an outlet or the like. The power supply circuit 100 converts the AC power supplied from the commercial power supply PS into DC power corresponding to the drive circuit 32, and supplies the converted DC power to the drive circuit 32. The drive circuit 32 operates by the DC power supplied from the power supply circuit 100.

[0043] When the control unit 24 receives a signal from the operation unit 22 indicating the start of toilet flushing, it switches the path of the switching valve 53 so that flushing water is supplied to the rim-side water supply channel 42 and opens the water supply valve 51. As a result, flushing water is supplied to the rim outlet 13 of the toilet bowl body 10, and rim flushing begins. In addition, the control unit 24 opens the water supply valve 51 and sends a control signal to the drive circuit 32, causing the drive circuit 32 to drive the pump 30. As a result, flushing water is supplied to the jet outlet 14 of the toilet bowl body 10, and jet flushing begins along with rim flushing.

[0044] In this way, toilet system 2 flushes the toilet bowl using both rim water discharge and jet water discharge. For rim water discharge, water is supplied using the water pressure (direct pressure) of the water supply. On the other hand, for jet water discharge, flushing water stored in tank 28 is supplied while being pressurized by pump 30. Toilet system 2 is, for example, a hybrid type (direct water pressure type + tank water supply type) toilet system (flush toilet system).

[0045] The control unit 24 supplies a predetermined amount of flushing water and then stops the pump 30. After stopping the pump 30, the control unit 24 switches the path of the switching valve 53 so that flushing water is supplied to the tank-side water supply passage 44, thereby replenishing the tank 28 with flushing water. After replenishing the tank 28 with a predetermined amount of flushing water, the control unit 24 closes the water supply valve 51. This completes the toilet flushing operation.

[0046] Figure 2 is a schematic block diagram showing the power supply circuit according to the embodiment. As shown in Figure 2, the power supply circuit 100 includes a rectifier circuit 102, an input capacitor 104, and a step-down circuit 106.

[0047] The rectifier circuit 102 converts AC power supplied from the commercial power supply PS into rectified power by rectifying the AC power. The rectifier circuit 102 is, for example, a full-wave rectifier circuit using a diode bridge. However, the rectifier circuit 102 is not limited to this, and may also be a half-wave rectifier circuit or the like.

[0048] The input capacitor 104 converts the rectified power rectified by the rectifier circuit 102 into DC power by smoothing it. In other words, the input capacitor 104 is an input-side smoothing capacitor.

[0049] The step-down circuit 106 steps down the voltage of the DC power supplied from the input capacitor 104 to a voltage corresponding to the drive circuit 32. The step-down circuit 106 supplies the stepped-down DC power to the drive circuit 32. In other words, the step-down circuit 106 converts the first DC power supplied from the input capacitor 104 into a second DC power with a lower voltage than the first DC power, and supplies the converted second DC power to the drive circuit 32.

[0050] As shown in Figure 2, the power supply circuit 100 supplies the second DC power, which has been stepped down by the step-down circuit 106, to the drive circuit 32, and also supplies the first DC power, which has not been stepped down by the step-down circuit 106, to the drive circuit 32.

[0051] The drive circuit 32 operates based on the second DC power and switches between supplying the first DC power to the pump 30 and stopping the supply of the first DC power to the pump 30 in response to a control signal from the control unit 24, thereby switching the operation and stopping of the pump 30. The pump 30 is driven by the first DC power supplied via the drive circuit 32 and supplies the cleaning water stored in the tank 28 to the jet outlet 14. In other words, the second DC power is the DC power required to operate the drive circuit 32. In other words, the first DC power is the DC power required to operate the pump 30.

[0052] The voltage of the first DC power source is higher than the voltage of the second DC power source. For example, if the AC power voltage of the commercial power supply PS is 100V (RMS), the voltage of the first DC power source is approximately 140V. In contrast, the voltage of the second DC power source is approximately 15V (for example, between 10V and 20V). Thus, the voltage of the first DC power source is more than twice as high as the voltage of the second DC power source.

[0053] In other words, the power supply circuit 100 supplies DC power to the drive circuit 32 and also supplies DC power to the pump 30. The pump 30 is a load that consumes a relatively large amount of power compared to the drive circuit 32. Therefore, when switching between driving and stopping the pump 30, the DC power supplied from the input capacitor 104 to the step-down circuit 106 may fluctuate, potentially causing the step-down circuit 106 to become unstable. In other words, when switching between driving and stopping the pump 30, the second DC power supplied from the step-down circuit 106 to the drive circuit 32 may become unstable.

[0054] Therefore, the capacitance of the input capacitor 104 is set to a relatively high capacitance. For example, the capacitance of the input capacitor 104 is set to about 1000μF (500μF to 10000μF). This makes it possible to suppress the instability of the step-down circuit 106 when supplying DC power to the pump 30 and the drive circuit 32.

[0055] In this example, the power supply circuit 100 supplies DC power to the pump 30 via the drive circuit 32. However, the power supply circuit 100 may also supply DC power directly to the pump 30. The drive circuit 32 may, for example, switch the operation of the pump 30 on and off by switching the power supply on and off within the pump 30. Whether the power supply circuit 100 supplies the first DC power necessary to operate the pump 30 to the drive circuit 32 or to the pump 30 directly can be appropriately selected depending on the configuration of the pump 30.

[0056] Figure 3 is a schematic block diagram showing a step-down circuit according to the embodiment. As shown in Figure 3, the step-down circuit 106 includes a pair of input terminals 110a and 110b, a pair of output terminals 112a and 112b, a control element 114, an inductor 116, a first rectifier element 121, a second rectifier element 122, an output capacitor 124, and a capacitor 126 for the control element.

[0057] A pair of input terminals 110a and 110b are connected to both ends of the input capacitor 104. Input terminal 110a is connected to the high-potential terminal of the input capacitor 104, and input terminal 110b is connected to the low-potential terminal of the input capacitor 104. As a result, the first DC power of the input capacitor 104 is supplied to the step-down circuit 106 via the pair of input terminals 110a and 110b. Input terminal 110a is the high-potential input terminal, and input terminal 110b is the low-potential input terminal.

[0058] The potential of the input terminal 110b and the low-potential terminal of the input capacitor 104 is set to, for example, the ground potential. The ground potential is, for example, the earth potential. However, the ground potential is not limited to the earth potential; it may also be the chassis ground potential or the frame ground potential, etc.

[0059] The pair of output terminals 112a and 112b are connected to the drive circuit 32. The step-down circuit 106 outputs the stepped-down second DC power from the pair of output terminals 112a and 112b. As a result, the second DC power is supplied from the step-down circuit 106 to the drive circuit 32 via the pair of output terminals 112a and 112b.

[0060] Output terminal 112a is the high-potential output terminal, and output terminal 112b is the low-potential output terminal. The potential of output terminal 112b is set to, for example, the ground potential. The potential of output terminal 112b is set to, for example, substantially the same potential as the input terminal 110b and the low-potential terminal of input capacitor 104.

[0061] The control element 114 comprises a switching element 130, a control circuit 132, and a package 134. The control element 114 is an IC that integrates the switching element 130 and the control circuit 132 within the package 134. In other words, the control element 114 is an IC that integrates the switching element 130 and the control circuit 132 into a single package. The control element 114 is, for example, a power supply IC.

[0062] The switching element 130 has a pair of main terminals 130a and 130b and a control terminal 130c. The switching element 130 has an ON state in which current flows between the pair of main terminals 130a and 130b, and an OFF state in which the flow of current between the pair of main terminals 130a and 130b is interrupted. The switching element 130 switches between the ON state and the OFF state according to the voltage applied between the pair of main terminals 130a and 130b and the voltage applied to the control terminal 130c. Note that the OFF state is not limited to a state in which no current flows at all between the pair of main terminals 130a and 130b, but may also be a state in which a weak current flows between the pair of main terminals 130a and 130b, such that it does not affect the operation of the step-down circuit 106. In other words, the ON state is the first state in which current flows between the pair of main terminals 130a and 130b, and the OFF state is the second state in which the magnitude of the current flowing between the pair of main terminals 130a and 130b is smaller than that of the first state.

[0063] The switching element 130 is, for example, a MOSFET. In this case, the main terminal 130a is the drain, the main terminal 130b is the source, and the control terminal 130c is the gate. However, the switching element 130 is not limited to this, and may also be a bipolar transistor, for example. The switching element 130 may be any switching element that can be stacked in the package 134 together with the control circuit 132.

[0064] The control circuit 132 controls the switching of the switching element 130. In other words, the control circuit 132 controls the switching between the on and off states of the switching element 130. The control circuit 132 is connected to the control terminal 130c of the switching element 130, and controls the switching of the switching element 130 by controlling the magnitude of the voltage applied to the control terminal 130c.

[0065] Package 134 has a first terminal 134a, a second terminal 134b, and a third terminal 134c. One main terminal 130a of the switching element 130 is connected to the first terminal 134a within package 134. The other main terminal 130b of the switching element 130 is connected to the second terminal 134b within package 134.

[0066] Furthermore, the first terminal 134a is connected to the high-potential input terminal 110a on the outside of the package 134. As a result, when the switching element 130 is turned on, the first DC power input from the input capacitor 104 is output from the second terminal 134b. When the switching element 130 is turned off, the output of the first DC power from the second terminal 134b is stopped.

[0067] One end of the inductor 116 is connected to the second terminal 134b of the control element 114. The other end of the inductor 116 is connected to the high-potential output terminal 112a.

[0068] The cathode of the first rectifier element 121 is connected to the connection point between the second terminal 134b of the control element 114 and one end of the inductor 116. The anode of the first rectifier element 121 is connected to the low-potential output terminal 112b.

[0069] One end of the output capacitor 124 is connected to the connection point between the other end of the inductor 116 and the high-potential output terminal 112a. The other end of the output capacitor 124 is connected to the low-potential output terminal 112b. In other words, the output capacitor 124 is connected in parallel to the pair of output terminals 112a and 112b.

[0070] Second rectifier element 122 anode It is connected to the connection point between the other end of the inductor 116 and the high-potential output terminal 112a. cathode This is connected to the third terminal 134c of the control element 114. The first rectifier element 121 and the second rectifier element 122 are, for example, diodes.

[0071] The reverse recovery time of the first rectifier element 121 is shorter than the reverse recovery time of the second rectifier element 122. In other words, the switching speed of the first rectifier element 121 is faster than the switching speed of the second rectifier element 122. The first rectifier element 121 is, for example, a high-speed rectifier diode. For example, a fast-recovery diode is used for the first rectifier element 121. The second rectifier element 122 is, for example, a general-purpose rectifier diode.

[0072] The reverse recovery time of the first rectifier element 121 is, for example, between 10 ns (nanoseconds) and 100 ns. The reverse recovery time of the second rectifier element 122 is, for example, between 2 μs (microseconds) and 10 μs. The reverse recovery time of the second rectifier element 122 is, for example, 20 times or more the reverse recovery time of the first rectifier element 121. Also, the reverse recovery time of the second rectifier element 122 is, for example, 1000 times or less the reverse recovery time of the first rectifier element 121.

[0073] One end of the control element capacitor 126 is connected to the second rectifier element 122. cathode It is connected to the connection point between the control element 114 and its third terminal 134c. The other end of the control element capacitor 126 is connected to the connection point between the control element 114's second terminal 134b and one end of the inductor 116. In other words, the control element capacitor 126 is provided between the control element 114's second terminal 134b and its third terminal 134c.

[0074] The capacitance of the control element capacitor 126 is smaller than the capacitance of the output capacitor 124. The capacitance of the output capacitor 124 is, for example, 220 μF (for example, 100 μF to 300 μF). The capacitance of the control element capacitor 126 is, for example, 2.2 μF (for example, 1 μF to 3 μF). The capacitance of the output capacitor 124 is set to, for example, about 100 times the capacitance of the output capacitor 124 (for example, 10 to 200 times).

[0075] In the control element 114, the potential of the second terminal 134b becomes the reference potential. In other words, the second terminal 134b is the ground terminal of the control element 114. Thus, the reference potential of the control element 114 is different from the reference potential of the load, the drive circuit 32 (the potential of the output terminal 112b). In other words, the ground potential of the control element 114 is not the same as the ground potential of the drive circuit 32.

[0076] Furthermore, the control element 114 operates based on the voltage applied to the third terminal 134c. In other words, the control element 114 operates based on the potential difference between the potential of the second terminal 134b and the potential of the third terminal 134c. The third terminal 134c is, in other words, the power supply terminal of the control element 114.

[0077] As described above, the third terminal 134c is connected to the control element capacitor 126. The voltage of the control element capacitor 126 is applied to the third terminal 134c. That is, the control element 114 operates based on the voltage of the control element capacitor 126. The control circuit 132 is connected to the first terminal 134a within the package 134. The control circuit 132 operates based on the voltage of the control element capacitor 126.

[0078] Furthermore, the control element 114 has a starting circuit (not shown) that charges the control element capacitor 126 based on the first DC power input to the first terminal 134a from the input capacitor 104 when the voltage of the control element capacitor 126 drops and the control element stops operating.

[0079] When the control element 114 is in a stopped state, it charges the control element capacitor 126 based on the first DC power input to the first terminal 134a, and starts operating when the voltage of the control element capacitor 126 (the voltage at the third terminal 134c) exceeds a predetermined value. In other words, when the voltage at the third terminal 134c exceeds a predetermined value, the control circuit 132 starts operating. The first terminal 134a is, in other words, the input terminal of the control element 114.

[0080] The control circuit 132 of the control element 114 switches the switching element 130 between the on and off states after it starts operating. Also, after it starts operating, the control circuit 132 stops charging the capacitor 126 for the control element by the start circuit.

[0081] When the switching element 130 is turned on, the first DC power input to the first terminal 134a is output from the second terminal 134b, energy is stored in the inductor 116, and the output capacitor 124 is charged.

[0082] When the switching element 130 is turned on, the voltage at the second terminal 134b becomes substantially the same as the voltage at the first terminal 134a. As a result, the potential of the cathode side of the first rectifier element 121 becomes higher than the potential of the anode side of the first rectifier element 121, and when the switching element 130 is turned on, substantially no current flows through the first rectifier element 121.

[0083] Furthermore, when the switching element 130 is turned on, the potential of the cathode side of the second rectifier element 122 becomes higher than the potential of the anode side of the second rectifier element 122 by the voltage of the control element capacitor 126. Therefore, when the switching element 130 is turned on, virtually no current flows through the second rectifier element 122.

[0084] When the switching element 130 is turned off, the output of the first DC power from the second terminal 134b is stopped, and the energy stored in the inductor 116 is output to the output capacitor 124 via the first rectifier element 121.

[0085] When the switching element 130 is turned off, the energy stored in the inductor 116 causes a regenerative current I1 to flow through the path formed by the inductor 116, the first rectifier element 121, and the output capacitor 124, as shown in Figure 3. The regenerative current I1 flows in a direction corresponding to the rectification direction of the first rectifier element 121. The output capacitor 124 is also charged by this regenerative current I1. In other words, the first rectifier element 121 is a rectifier element placed on the path through which the regenerative current I1 flows. In other words, the output capacitor 124 is a capacitor placed on the path through which the regenerative current I1 flows.

[0086] Furthermore, when the switching element 130 is turned off, the energy stored in the inductor 116 is output to the control element capacitor 126 via the second rectifier element 122. Consequently, the control element capacitor 126 is also charged via the second rectifier element 122. This suppresses a drop in the voltage of the control element capacitor 126 even after the charging of the control element capacitor 126 by the startup circuit is stopped. In other words, the drop in the voltage supplied to the control element 114 is suppressed.

[0087] When the switching element 130 is turned off, the energy stored in the inductor 116 causes a feedback current I2 to flow through the path formed by the inductor 116, the second rectifier element 122, and the control element capacitor 126, as shown in Figure 3. The feedback current I2 flows in a direction corresponding to the rectification direction of the second rectifier element 122. The control element capacitor 126 is charged by this feedback current I2. In other words, the second rectifier element 122 is a rectifier element placed on the path through which the feedback current I2 flows. In other words, the control element capacitor 126 is a capacitor placed on the path through which the feedback current I2 flows.

[0088] The step-down circuit 106 steps down the voltage across the input capacitor 104 by time division through the switching of the switching element 130, and smooths it with the inductor 116 and the output capacitor 124 to obtain a DC voltage of the desired magnitude. In other words, the output capacitor 124 is the output-side smoothing capacitor.

[0089] In the step-down circuit 106, the magnitude of the output voltage can be adjusted by the ratio of the on time to the off time (duty cycle) of the switching element 130. For example, if the duty cycle is set to 50%, the output voltage can be set to 50% of the input voltage. The step-down circuit 106 is, for example, an asynchronous rectification type step-down converter (buck converter).

[0090] The control circuit 132 controls the switching of the switching element 130 so that the voltage of the second DC power output from the pair of output terminals 112a and 112b becomes a voltage of a predetermined magnitude.

[0091] Furthermore, the control circuit 132 has a feedback function. When the control circuit 132 is operating, the voltage of the control element capacitor 126 (voltage at the third terminal 134c) rises based on the energy output from the inductor 116 when the switching element 130 is off, and falls based on the power consumption of the control element 114 when the switching element 130 is on. Therefore, the voltage at the third terminal 134c changes in accordance with the switching of the switching element 130. In other words, the voltage at the third terminal 134c changes in accordance with the voltage of the second DC power output from the pair of output terminals 112a and 112b.

[0092] The control circuit 132 performs feedback control of the switching of the switching element 130 so that the voltage at the third terminal 134c becomes a predetermined voltage. For example, if the voltage at the third terminal 134c is lower than the predetermined voltage, the control circuit 132 increases the duty cycle of the switching element 130 (increases the on time). Conversely, if the voltage at the third terminal 134c is higher than the predetermined voltage, the control circuit 132 decreases the duty cycle of the switching element 130 (shortens the on time).

[0093] In this way, the control circuit 132 performs feedback control of the switching of the switching element 130 so that the voltage at the third terminal 134c becomes a predetermined voltage, thereby ensuring that the voltage of the second DC power output from the pair of output terminals 112a and 112b becomes a predetermined constant voltage. This enables a stable supply of the second DC power to the drive circuit 32.

[0094] In the step-down circuit 106, for example, the circuit constants of each part, such as the inductor 116 and the output capacitor 124, are set so that when the voltage at the third terminal 134c is a predetermined voltage, the voltage of the second DC power output from the pair of output terminals 112a and 112b (output voltage) becomes a predetermined voltage.

[0095] Thus, the third terminal 134c functions as a power supply terminal for the control element 114, and also as a control terminal for the control circuit 132 to perform feedback control. This type of feedback control method is sometimes called, for example, a power supply voltage feedback method (VCC feedback method). The power supply control of the step-down circuit 106 is sometimes called, for example, a high-side flyback VCC feedback method power supply control.

[0096] As described above, in a step-down circuit 106 using a control element 114 with a feedback function, there is a possibility that the output voltage of the step-down circuit 106 may become lower than the desired voltage. As a result of diligent investigation, the inventors of the present invention have found that when the reverse recovery time of the first rectifier element 121 is longer than the reverse recovery time of the second rectifier element 122, the output voltage of the step-down circuit 106 becomes lower than the desired voltage. In other words, they have found that when the switching speed of the first rectifier element 121 is slower than the switching speed of the second rectifier element 122, the output voltage of the step-down circuit 106 becomes lower than the desired voltage.

[0097] If the reverse recovery time of the first rectifier element 121 is longer than the reverse recovery time of the second rectifier element 122, when the switching element 130 switches from the ON state to the OFF state, the feedback current I2 flows to the second rectifier element 122 before the regenerative current I1 flows to the first rectifier element 121. In other words, if the reverse recovery time of the first rectifier element 121 is longer than the reverse recovery time of the second rectifier element 122, the current discharged from the inductor 116 in a short time will primarily flow to the second rectifier element 122 because the second rectifier element 122 turns on before the first rectifier element 121.

[0098] The voltage at the third terminal 134c tends to rise quickly as a time constant because the load is small and the capacitance of the control element capacitor 126 is small compared to the capacitance of the output capacitor 124. Therefore, if the second rectifier element 122 turns on before the first rectifier element 121, the voltage at the third terminal 134c (the voltage of the control element capacitor 126) tends to rise more easily than the voltage at the output capacitor 124. As described above, the control circuit 132 reduces the duty cycle of the switching element 130 in response to the voltage at the third terminal 134c, which is thought to cause the output voltage of the step-down circuit 106 to become lower than the desired voltage.

[0099] In contrast, in the toilet device 2 and power supply circuit 100 according to this embodiment, the reverse recovery time of the first rectifier element 121 is shorter than the reverse recovery time of the second rectifier element 122. This allows the current discharged from the inductor 116 in a short period of time to flow primarily to the first rectifier element 121, suppressing the tendency for the voltage of the control element capacitor 126 to rise more easily than the voltage of the output capacitor 124. This prevents the output voltage of the step-down circuit 106 from falling below the desired voltage.

[0100] Furthermore, in the toilet device 2 and power supply circuit 100 according to this embodiment, it is also possible to suppress an increase in the power consumption of the power supply circuit 100 compared to a method of stabilizing the output voltage of the step-down circuit 106 by adjusting the resistance value of a resistive element (so-called bleeder resistor) provided in parallel with the load (drive circuit 32) at a pair of output terminals 112a and 112b of the step-down circuit 106.

[0101] Therefore, in the toilet device 2 and power supply circuit 100 according to this embodiment, even when a control element 114 with a feedback function is used in the step-down circuit 106, it is possible to suppress an increase in power consumption while preventing the output voltage of the step-down circuit 106 from falling below the desired voltage.

[0102] In the toilet device 2 and power supply circuit 100 according to this embodiment, the capacitance of the control element capacitor 126 is smaller than the capacitance of the output capacitor 124. In the toilet device 2 and power supply circuit 100 according to this embodiment, by making the reverse recovery time of the first rectifier element 121 shorter than the reverse recovery time of the second rectifier element 122, it is possible to suppress the output voltage of the step-down circuit 106 from becoming lower than the desired voltage while suppressing the capacitance of the control element capacitor 126 from becoming unnecessarily large.

[0103] In the toilet device 2 and power supply circuit 100 according to this embodiment, the reverse recovery time of the first rectifier element 121 is 10 ns or more and 100 ns or less, and the reverse recovery time of the second rectifier element is 2 μs or more and 10 μs or less. This allows the current discharged from the inductor 116 in a short period of time to flow more appropriately on the first rectifier element 121 side, and more effectively suppresses the tendency for the voltage of the control element capacitor 126 to rise more easily than the voltage of the output capacitor 124. This makes it possible to more effectively suppress the output voltage of the step-down circuit 106 from falling below the desired voltage.

[0104] In the toilet device 2 and power supply circuit 100 according to this embodiment, the reverse recovery time of the second rectifier element 122 is 20 times or more the reverse recovery time of the first rectifier element 121. This allows the current discharged from the inductor 116 in a short period of time to flow more appropriately to the first rectifier element 121, and more effectively suppresses the tendency for the voltage of the control element capacitor 126 to rise more easily than the voltage of the output capacitor 124. This makes it possible to more effectively suppress the output voltage of the step-down circuit 106 from falling below the desired voltage.

[0105] Furthermore, in the toilet device 2 and power supply circuit 100 according to this embodiment, the reverse recovery time of the second rectifier element 122 is 1000 times or less the reverse recovery time of the first rectifier element 121. This prevents, for example, excessive current discharged from the inductor 116 in a short period of time from flowing to the first rectifier element 121 side, which would cause the voltage of the control element capacitor 126 to become lower than the voltage of the output capacitor 124. This prevents the output voltage of the step-down circuit 106 from becoming higher than the desired voltage.

[0106] Each of the above embodiments shows a hybrid toilet device 2 that cleans the toilet bowl using rim water discharge and jet water discharge. The toilet device 2 is not limited to a hybrid type; it may also be a toilet device that only discharges rim water, or a toilet device that only discharges jet water, and so on.

[0107] Pump 30 is not limited to a pump that pressurizes the flushing water stored in the tank 28 and supplies it to the jet outlet 14 (toilet bowl body 10), but may also be a pump that supplies flushing water to the rim outlet 13, for example. Furthermore, pump 30 is not limited to a pump that supplies flushing water stored in the tank 28 to the toilet bowl body 10, but may also be a pump that pressurizes flushing water supplied from a water source and supplies it to the toilet bowl body 10, for example. Pump 30 may be any pump that supplies flushing water to the toilet bowl body 10.

[0108] Toilet device 2 may be any toilet device that includes at least a toilet bowl, a pump for supplying flushing water to the toilet bowl, and a drive circuit for switching the operation of the pump on and off.

[0109] This embodiment includes the following aspects. (Note 1) A power supply circuit for a toilet system, which is used in a toilet system comprising a toilet bowl body, a pump for supplying flushing water to the toilet bowl body, and a drive circuit for switching the operation and stopping of the pump, and which supplies power to the drive circuit, A rectifier circuit that converts AC power supplied from a commercial power source into rectified power, An input capacitor that converts the rectified power into DC power by smoothing the rectified power, A step-down circuit that converts the first DC power supplied from the input capacitor into a second DC power with a lower voltage than the first DC power, and supplies the second DC power to the drive circuit, Equipped with, The step-down circuit includes a pair of input terminals, a pair of output terminals, a control element, an inductor, a first rectifier element, a second rectifier element, an output capacitor, and a capacitor for the control element. The pair of input terminals are connected to both ends of the input capacitor, The pair of output terminals are connected to the drive circuit, The control element comprises a switching element, a control circuit for controlling the switching of the switching element, and a package, wherein the switching element and the control circuit are built into the package. The switching element has a pair of main terminals and a control terminal. The package has a first terminal, a second terminal, and a third terminal. One of the main terminals of the switching element is connected to the first terminal within the package. The other main terminal of the switching element is connected to the second terminal within the package. One end of the inductor is connected to the second terminal, The other end of the inductor is connected to the output terminal on the high-potential side. The cathode of the first rectifier element is connected to the connection point between the second terminal and the one end of the inductor. The anode of the first rectifier element is connected to the output terminal on the low-potential side. One end of the output capacitor is connected to the connection point between the other end of the inductor and the output terminal on the high-potential side. The other end of the output capacitor is connected to the output terminal on the low-potential side. The second rectifier element anode It is connected to the connection point between the other end of the inductor and the output terminal on the high-potential side. The second rectifier element cathode It is connected to the third terminal, One end of the capacitor for the control element is connected to the second rectifier element. cathode It is connected to the connection point between the third terminal and the third terminal, The other end of the capacitor for the control element is connected to the connection point between the second terminal and the one end of the inductor. The control circuit has a feedback function and performs feedback control of the switching of the switching element so that the voltage at the third terminal becomes a predetermined voltage. A power supply circuit for a toilet device, characterized in that the reverse recovery time of the first rectifier element is shorter than the reverse recovery time of the second rectifier element.

[0110] (Note 2) The power supply circuit for a toilet device according to Appendix 1, characterized in that the capacitance of the capacitor for the control element is smaller than the capacitance of the output capacitor.

[0111] (Note 3) The reverse recovery time of the first rectifier element is 10 ns or more and 100 ns or less. The power supply circuit for a toilet device according to Appendix 1 or 2, characterized in that the reverse recovery time of the second rectifier element is 2 μs or more and 10 μs or less.

[0112] (Note 4) The power supply circuit for a toilet device according to claim 1, as described in any one of appendices 1 to 3, characterized in that the reverse recovery time of the second rectifier element is 20 times or more the reverse recovery time of the first rectifier element.

[0113] (Note 5) The toilet bowl itself, A pump that supplies flushing water to the toilet bowl body, A drive circuit that switches between driving and stopping the pump, A power supply circuit that supplies power to the aforementioned drive circuit, Equipped with, The aforementioned power supply circuit is A rectifier circuit that converts AC power supplied from a commercial power source into rectified power, An input capacitor that converts the rectified power into DC power by smoothing the rectified power, A step-down circuit that converts the first DC power supplied from the input capacitor into a second DC power with a lower voltage than the first DC power, and supplies the second DC power to the drive circuit, It has, The step-down circuit includes a pair of input terminals, a pair of output terminals, a control element, an inductor, a first rectifier element, a second rectifier element, an output capacitor, and a capacitor for the control element. The pair of input terminals are connected to both ends of the input capacitor, The pair of output terminals are connected to the drive circuit, The control element comprises a switching element, a control circuit for controlling the switching of the switching element, and a package, wherein the switching element and the control circuit are built into the package. The switching element has a pair of main terminals and a control terminal. The package has a first terminal, a second terminal, and a third terminal. One of the main terminals of the switching element is connected to the first terminal within the package. The other main terminal of the switching element is connected to the second terminal within the package. One end of the inductor is connected to the second terminal, The other end of the inductor is connected to the output terminal on the high-potential side. The cathode of the first rectifier element is connected to the connection point between the second terminal and the one end of the inductor. The anode of the first rectifier element is connected to the output terminal on the low-potential side. One end of the output capacitor is connected to the connection point between the other end of the inductor and the output terminal on the high-potential side. The other end of the output capacitor is connected to the output terminal on the low-potential side. The second rectifier element anode It is connected to the connection point between the other end of the inductor and the output terminal on the high-potential side. The second rectifier element cathode It is connected to the third terminal, One end of the capacitor for the control element is connected to the second rectifier element. cathode It is connected to the connection point between the third terminal and the third terminal, The other end of the capacitor for the control element is connected to the connection point between the second terminal and the one end of the inductor. The control circuit has a feedback function and performs feedback control of the switching of the switching element so that the voltage at the third terminal becomes a predetermined voltage. A toilet device characterized in that the reverse recovery time of the first rectifier element is shorter than the reverse recovery time of the second rectifier element.

[0114] Embodiments of the present invention have been described above. However, the present invention is not limited to these descriptions. Modifications made by those skilled in the art to the above-described embodiments are also included within the scope of the present invention, as long as they retain the features of the present invention. For example, the shape, dimensions, materials, and arrangement of each element of the toilet device 2 and power supply circuit 100 are not limited to those exemplified and can be modified as appropriate. Furthermore, the elements of each of the embodiments described above can be combined to the extent technically possible, and these combinations are also included within the scope of the present invention insofar as they include the features of the present invention. [Explanation of symbols]

[0115] 2...Toilet equipment, 10...Toilet bowl body, 11...Bowl section, 12...Drain trap pipe, 13...Rim spout, 14...Jet spout, 20...Toilet flushing device, 22...Operation unit, 24...Control unit, 26...Valve unit, 28...Tank, 30...Pump, 32...Drive circuit, 40...Water supply channel, 42...Rim side water supply channel, 44...Tank side water supply channel, 46...Drain channel, 50...Constant flow valve, 51...Water supply valve, 52...Vacuum breaker, 53...Switching valve, 54...Water receiving section, 60...Water supply pipe, 62...Water supply pipe, 100...Power supply circuit, 102...Rectifier circuit, 104...Input capacitor, 106...Step-down circuit, 110a, 110b...Input terminals 112a, 112b…Output terminals, 114…Control element, 116…Inductor, 121…First rectifier element, 122…Second rectifier element, 124…Output capacitor, 126…Capacitor for control element, 130…Switching element, 132…Control circuit, 134…Package, PS…Commercial power supply

Claims

1. A power supply circuit for a toilet system, which is used in a toilet system comprising a toilet bowl body, a pump for supplying flushing water to the toilet bowl body, and a drive circuit for switching the operation and stopping of the pump, and which supplies power to the drive circuit, A rectifier circuit that converts AC power supplied from a commercial power source into rectified power, An input capacitor that converts the rectified power into DC power by smoothing the rectified power, A step-down circuit that converts the first DC power supplied from the input capacitor into a second DC power with a lower voltage than the first DC power, and supplies the second DC power to the drive circuit, Equipped with, The step-down circuit includes a pair of input terminals, a pair of output terminals, a control element, an inductor, a first rectifier element, a second rectifier element, an output capacitor, and a capacitor for the control element. The pair of input terminals are connected to both ends of the input capacitor, The pair of output terminals are connected to the drive circuit, The control element comprises a switching element, a control circuit for controlling the switching of the switching element, and a package, wherein the switching element and the control circuit are built into the package. The switching element has a pair of main terminals and a control terminal. The package has a first terminal, a second terminal, and a third terminal. One of the main terminals of the switching element is connected to the first terminal within the package. The other main terminal of the switching element is connected to the second terminal within the package. One end of the inductor is connected to the second terminal, The other end of the inductor is connected to the output terminal on the high-potential side. The cathode of the first rectifier element is connected to the connection point between the second terminal and the one end of the inductor. The anode of the first rectifier element is connected to the output terminal on the low-potential side. One end of the output capacitor is connected to the connection point between the other end of the inductor and the output terminal on the high-potential side. The other end of the output capacitor is connected to the output terminal on the low-potential side. The anode of the second rectifier element is connected to the connection point between the other end of the inductor and the output terminal on the high-potential side. The cathode of the second rectifier element is connected to the third terminal. One end of the capacitor for the control element is connected to the connection point between the cathode of the second rectifier element and the third terminal. The other end of the capacitor for the control element is connected to the connection point between the second terminal and the one end of the inductor. The control circuit has a feedback function and performs feedback control of the switching of the switching element so that the voltage at the third terminal becomes a predetermined voltage. The reverse recovery time of the first rectifier element is shorter than the reverse recovery time of the second rectifier element. The capacitance of the control element capacitor is smaller than the capacitance of the output capacitor. A power supply circuit for a toilet device, characterized in that the capacitance of the input capacitor is greater than the capacitance of the output capacitor.

2. The power supply circuit for a toilet device according to Claim 1, characterized in that the capacitance of the input capacitor is 500 μF or more and 10,000 μF or less.

3. The reverse recovery time of the first rectifier element is 10 ns or more and 100 ns or less. The power supply circuit for a toilet device according to claim 1, characterized in that the reverse recovery time of the second rectifier element is 2 μs or more and 10 μs or less.

4. The power supply circuit for a toilet device according to claim 1, characterized in that the reverse recovery time of the second rectifier element is 20 times or more the reverse recovery time of the first rectifier element.

5. The toilet bowl itself, A pump that supplies flushing water to the toilet bowl body, A drive circuit that switches between driving and stopping the pump, A power supply circuit that supplies power to the aforementioned drive circuit, Equipped with, The aforementioned power supply circuit is A rectifier circuit that converts AC power supplied from a commercial power source into rectified power, An input capacitor that converts the rectified power into DC power by smoothing the rectified power, A step-down circuit that converts the first DC power supplied from the input capacitor into a second DC power with a lower voltage than the first DC power, and supplies the second DC power to the drive circuit, It has, The step-down circuit includes a pair of input terminals, a pair of output terminals, a control element, an inductor, a first rectifier element, a second rectifier element, an output capacitor, and a capacitor for the control element. The pair of input terminals are connected to both ends of the input capacitor, The pair of output terminals are connected to the drive circuit, The control element comprises a switching element, a control circuit for controlling the switching of the switching element, and a package, wherein the switching element and the control circuit are built into the package. The switching element has a pair of main terminals and a control terminal. The package has a first terminal, a second terminal, and a third terminal. One of the main terminals of the switching element is connected to the first terminal within the package. The other main terminal of the switching element is connected to the second terminal within the package. One end of the inductor is connected to the second terminal, The other end of the inductor is connected to the output terminal on the high-potential side. The cathode of the first rectifier element is connected to the connection point between the second terminal and the one end of the inductor. The anode of the first rectifier element is connected to the output terminal on the low-potential side. One end of the output capacitor is connected to the connection point between the other end of the inductor and the output terminal on the high-potential side. The other end of the output capacitor is connected to the output terminal on the low-potential side. The anode of the second rectifier element is connected to the connection point between the other end of the inductor and the output terminal on the high-potential side. The cathode of the second rectifier element is connected to the third terminal. One end of the capacitor for the control element is connected to the connection point between the cathode of the second rectifier element and the third terminal. The other end of the capacitor for the control element is connected to the connection point between the second terminal and the one end of the inductor. The control circuit has a feedback function and performs feedback control of the switching of the switching element so that the voltage at the third terminal becomes a predetermined voltage. The reverse recovery time of the first rectifier element is shorter than the reverse recovery time of the second rectifier element. The capacitance of the control element capacitor is smaller than the capacitance of the output capacitor. A toilet device characterized in that the capacitance of the input capacitor is greater than the capacitance of the output capacitor.

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