Toilet seat device

Abstract

To provide a toilet seat device capable of suppressing the occurrence of erroneous detection of a human body by noise.SOLUTION: The toilet seat device is provided. It includes a toilet seat, a detection electrode in which electrostatic capacity changes according to seating of a human body on the toilet seat, electrostatic capacity detection means having an input terminal connected electrically to the detection electrode to detect the electrostatic capacity of the detection electrode, a control part for determining the existence / nonexistence of the seating of the human body on the basis of a detection result of the electrostatic capacity detection means, and overvoltage detection means for detecting overvoltage in the input terminal. When the overvoltage detection means detects the overvoltage, the electrostatic capacity detection means is restarted after temporarily stopping the detection of the electrostatic capacity.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE Aspects of the present invention generally relate to toilet seat apparatus. [Background technology]

[0002] There is a capacitance-type human body detection sensor that detects a human body by the change in capacitance according to the presence or absence of a human body. It has been proposed to use such a capacitance-type human body detection sensor in a toilet seat device. For example, in the toilet seat seat detection device of Patent Document 1, a heat-conductive conductor (aluminum foil) attached to a heater wire provided on the toilet seat is used as an electrode, and a change in capacitance is detected to detect the presence of a human body on the toilet seat. In a toilet seat device equipped with a capacitance sensor, there is a risk of false detection of a human body due to noise. For example, noise from the power line of the toilet seat device may reduce the accuracy of human body detection. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-138247 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made based on the recognition of such problems, and has an object to provide a toilet seat apparatus that can suppress erroneous detection of a human body caused by noise. [Means for solving the problem]

[0005] A first invention is a toilet seat device comprising: a toilet seat; a detection electrode whose capacitance changes depending on whether a human body is sitting on the toilet seat; a capacitance detection means having an input terminal electrically connected to the detection electrode and detecting the capacitance of the detection electrode; a control unit which determines whether or not a human body is sitting on the toilet seat based on the detection result of the capacitance detection means; and overvoltage detection means which detects overvoltage at the input terminal, wherein when the overvoltage detection means detects the overvoltage, the capacitance detection means temporarily suspends and then resumes detection of the capacitance.

[0006] According to this toilet seat device, even if an overvoltage occurs at the input terminal due to noise from a power source or the like, the capacitance detection means temporarily suspends detection of capacitance, thereby preventing erroneous detection due to noise.

[0007] A second invention is a toilet seat device according to the first invention, wherein the capacitance detection means has an integrating means for storing charge discharged from the detection electrode, a first switch connected to a predetermined voltage, and a second switch connected to the input terminal and the integrating means, and performs a switching operation that alternates between a first state in which the first switch is on and the second switch is off and the detection electrode is charged to the predetermined voltage, and a second state in which the first switch is off and the second switch is on and the detection electrode is discharged, the integrating means stores charge discharged from the detection electrode in the second state repeated by the switching operation, the control unit determines whether or not the human body is seated based on the charge accumulated in the integrating means, and when the overvoltage detection means detects the overvoltage, the capacitance detection means temporarily suspends the switching operation, sets the first switch and the second switch to the first state, and then resumes the switching operation.

[0008] According to this toilet seat device, when an overvoltage occurs at the input terminal due to, for example, noise from a power supply, the capacitance detection means suspends the switching operation and enters the first state. This stops the integration (accumulation of charge) of the integrating means, thereby making it possible to prevent a large error in the integral value caused by noise. Therefore, it is possible to prevent erroneous detection caused by noise.

[0009] A third invention is a toilet seat device according to the second invention, further comprising an off-delay means for causing the first state to continue for a predetermined period of time when the over-voltage detection means detects the over-voltage.

[0010] According to this toilet seat device, the first state continues, so that the integration by the integrating means continues to be suspended, making it possible to further prevent erroneous detection caused by noise. For example, there are cases where a state where noise occurs at the input terminal continues due to the inclusion of a capacitive component or an inductive component in the circuit of the toilet seat device. That is, since the circuit of the toilet seat device has a capacitive component and an inductive component, even if the applied overvoltage is momentary, the potential fluctuation due to the noise does not immediately become zero, and it takes a certain amount of time to converge. Even in such a case, by continuing the first state for a predetermined time by the off-delay means, the integration of the integrating means continues to be interrupted, so that time is secured until the potential fluctuation due to the noise converges, and it is possible to suppress the occurrence of a large error due to noise in the integrated value. Therefore, it is possible to further suppress the occurrence of erroneous detection due to noise.

[0011] A fourth invention is a toilet seat device according to any one of the first to third inventions, characterized in that the detection electrode is provided on the back surface of the toilet seat, has an area larger than a heater that warms the toilet seat, and diffuses heat from the heater to the toilet seat.

[0012] According to this toilet seat device, the large area of ​​the detection electrode widens the seating detection range, making it possible to suppress erroneous detection due to seating position. On the other hand, when the detection electrode is large, the capacitance of the detection electrode is large, so the charging and discharging time is long, and the time required for capacitance detection is also long. As a result, during capacitance detection, noise (such as short-period noise on the power line) can frequently cause overvoltage at the input terminal. Even in such cases, the capacitance detection means can temporarily suspend capacitance detection, thereby suppressing erroneous detection due to noise. Therefore, it is possible to suppress erroneous detection due to noise while widening the seating detection range.

[0013] A fifth invention is a toilet seat device according to the second or third invention, characterized in that the capacitance detection means is capable of changing the frequency of the switching operation that repeats the first state and the second state to a plurality of mutually different frequencies, and when changing the frequency of the switching operation, the time of one of the first state and the second state is made variable, and the time of the other of the first state and the second state is made fixed.

[0014] According to this toilet seat device, by changing the frequency of the switching operation, it is possible to reduce errors in the capacitance detection result caused by noise of a specific frequency. On the other hand, when the switching operation is switched between the first state and the second state, this switching operation may trigger a phenomenon in which the potential of the detection electrode oscillates. Here, if the frequency of the switching operation is changed, the effect of the vibration of the potential of the detection electrode on the capacitance detection result changes, which may result in erroneous detection of the presence or absence of a human body. In response to this, when the frequency of the switching operation is changed, the time of the other of the first state and the second state is fixed, thereby reducing the change in the effect of the vibration of the potential of the detection electrode caused by the change in frequency. This makes it possible to suppress erroneous detection.

[0015] A sixth invention is the toilet seat device according to the fifth invention, characterized in that the one is in the first state and the other is in the second state.

[0016] In the first state, the voltage of the detection electrode at the end of the first state affects the detection result of the capacitance detection means. For example, even if noise occurs in the detection electrode during the first state, there is no substantial effect on the detection result. Therefore, according to this toilet seat device, even if the time of the first state is extended and the possibility of noise entering the detection electrode during the first state increases, it is possible to suppress a decrease in noise resistance. Effect of the Invention

[0017] According to an aspect of the present invention, a toilet seat apparatus is provided that can suppress erroneous detection of a human body caused by noise. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a perspective view illustrating a toilet apparatus provided with a toilet seat apparatus according to an embodiment. [Diagram 2] FIG. 2 is a block diagram illustrating an example of a human body detection sensor included in the toilet seat apparatus according to the embodiment. [Diagram 3] FIG. 3 is a cross-sectional view that diagrammatically illustrates a portion of the toilet seat according to the embodiment. [Figure 4] FIG. 4 is a plan view that illustrates the toilet seat according to the embodiment. [Diagram 5] FIG. 5 is a partial cross-sectional view that diagrammatically illustrates a portion of the toilet seat according to the embodiment. [Figure 6] FIG. 6 is a block diagram that diagrammatically illustrates a toilet seat device according to an embodiment. [Figure 7] 7(a) to 7(d) are graphs that diagrammatically show an example of the operation of the detection circuit according to the embodiment. [Figure 8] 8(a) to 8(c) are graphs that diagrammatically show an example of the operation of the detection circuit according to the embodiment. [Figure 9] FIG. 9 is a schematic block diagram showing a human body detection sensor according to a reference example. [Figure 10]10(a) to 10(d) are graphs illustrating an example of the operation of the detection circuit according to the reference example. [Figure 11] 11(a) to 11(c) are graphs illustrating an example of the operation of the detection circuit according to the reference example. [Figure 12] FIG. 12 is a block diagram illustrating a specific example of a human body detection sensor according to the embodiment. [Figure 13] 13(a) to 13(g) are graphs that diagrammatically illustrate an example of the operation of the detection circuit according to the embodiment. [Figure 14] 14(a) to 14(f) are graphs that diagrammatically show an example of the operation of the detection circuit according to the embodiment. [Figure 15] FIG. 11 is a block diagram illustrating a toilet seat device according to another embodiment of the present invention. [Figure 16] 16(a) and 16(b) are graphs that diagrammatically show the switching operation according to the embodiment. [Figure 17] 17(a) and 17(b) are graphs that diagrammatically show the switching operation according to the embodiment. [Figure 18] 18(a) and 18(b) are graphs that diagrammatically show an example of the operation of the detection circuit. [Figure 19] 19(a) and 19(b) are graphs that diagrammatically show an example of the operation of the detection circuit. [Figure 20] 20(a) and 20(b) are graphs that diagrammatically show another example of the operation of the detection circuit. [Figure 21] 21(a) and 21(b) are graphs illustrating the timing at which the discharge time ends. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same components are designated by the same reference numerals and detailed description thereof will be omitted as appropriate. FIG. 1 is a perspective view illustrating a toilet apparatus provided with a toilet seat apparatus according to an embodiment. 1, the toilet apparatus 100 includes a toilet seat apparatus 110 according to an embodiment, and a Western-style seated toilet bowl (hereinafter, for convenience of explanation, simply referred to as a "toilet bowl") 104. The toilet seat apparatus 110 is provided on top of the toilet bowl 104. The toilet seat apparatus 110 includes a main body 112, a toilet seat 114, and a toilet lid 116.

[0020] The toilet 104 has a bowl portion 104a that is recessed downward. The toilet 104 receives waste such as urine and feces from the user in the bowl portion 104a. The main body portion 112 of the toilet seat device 110 is provided at an upper portion and behind the bowl portion 104a of the toilet 104. The main body portion 112 axially supports the toilet seat 114 and the toilet lid 116 so that they can be opened and closed.

[0021] The toilet seat 114 has an opening 114a. The toilet seat 114 is provided on the toilet bowl 104 so as to surround the outer edge of the bowl portion 104a, and exposes the bowl portion 104a through the opening 114a. This allows a user to excrete into the bowl portion 104a while sitting on the toilet seat 114. In this example, a so-called O-shaped toilet seat 114 is shown, in which a through-hole-like opening 114a is formed. The toilet seat 114 is not limited to an O-shape, and may be U-shaped, for example.

[0022] The toilet seat device 110 has a heating function that warms the seating surface of the toilet seat 114. The toilet seat device 110 also has a sanitary washing function that washes private parts such as the buttocks of a user sitting on the toilet seat 114. In other words, the toilet seat device 110 is a sanitary washing device. However, the toilet seat device 110 does not necessarily have to have the sanitary washing function or the heating function. The toilet seat device 110 may be, for example, a heated toilet seat device that has only a heating function.

[0023] The toilet seat device 110 has a nozzle 120 for washing the private parts of the human body. The nozzle 120 is provided in the main body part 112, and moves forward and backward between a position stored in the main body part 112 and a position advanced from the main body part 112 into the bowl part 104a. Note that Fig. 1 shows the state in which the nozzle 120 has advanced into the bowl part 104a.

[0024] The main body 112 is configured to be able to communicate with an operation unit 106 such as a remote control. The communication between the main body 112 and the operation unit 106 may be wired communication or wireless communication. The main body 112 advances the nozzle 120 into the bowl portion 104a in response to an operation instruction input from the operation unit 106, for example.

[0025] The nozzle 120 ejects water toward the human body parts to cleanse the human body parts. A bidet cleansing water outlet 120a and a buttocks cleansing water outlet 120b are provided at the tip of the nozzle 120. The nozzle 120 can eject water from the bidet cleansing water outlet 120a provided at its tip to clean the female parts of a woman sitting on the toilet seat 114. Alternatively, the nozzle 120 can eject water from the buttocks cleansing water outlet 120b provided at its tip to clean the buttocks of a user sitting on the toilet seat 114.

[0026] FIG. 2 is a block diagram illustrating an example of a human body detection sensor included in the toilet seat apparatus according to the embodiment. The toilet seat device 110 has a human body detection sensor 10. The human body detection sensor 10 has a detection electrode 12, a detection circuit 14, and a control unit 16.

[0027] The human body detection sensor 10 determines whether or not a human body is present. The human body detection sensor 10 is, for example, a seating detection sensor that can detect whether or not a user is seated on the toilet seat 114. The toilet seat device 110 can control the functions of the toilet seat device 110 based on the determination result of the human body detection sensor 10 as to whether or not a human body (seated) is present. For example, the control unit 16 can control the washing function (movement of the nozzle 120 back and forth and water spouting / stopping of the nozzle 120) and turn the heating function on and off based on the determination result of the human body detection sensor 10.

[0028] The capacitance of the detection electrode 12 changes depending on whether or not a human body is present. For example, the detection electrode 12 is attached to a toilet seat 114, and the capacitance changes depending on whether or not a human body is seated on the toilet seat 114. The detection electrode 12 is electrostatically coupled to the human body when the human body is seated. As a result, the capacitance of the detection electrode 12 is larger when the human body is seated than when the human body is not seated. That is, as shown in FIG. 2, the detection electrode 12 is connected to a common potential GND via the human body, for example, and forms a capacitance C1 (capacitor) that changes depending on whether or not a human body is present. The capacitance C1 changes depending on whether or not a human body is present (a seated state) and whether or not a human body is present (a not seated state). For example, when a pulse signal is transmitted to the detection electrode 12, the current flowing through the detection electrode 12 is larger when the human body is seated than when the human body is not seated. In this example, the human body detection sensor 10 is a so-called self-capacitance type capacitive human body detection sensor that detects a change in capacitance due to the presence or absence of a human body with one electrode.

[0029] The detection circuit 14 includes a capacitance detection unit 17 , an overvoltage detection unit 11 , and an off-delay unit 19 .

[0030] The capacitance detection means 17 has an input terminal 15 electrically connected to the detection electrode 12 . The capacitance detection means 17 detects a change in the capacitance of the detection electrode 12 by transmitting a signal to the detection electrode 12 via the input terminal 15. For example, the capacitance detection means 17 transmits a pulse signal of a predetermined number of pulses to the detection electrode 12 via the input terminal 15. Then, the capacitance detection means 17 detects, via the input terminal 15, the charge accumulated in the detection electrode 12 when each pulse is applied to the detection electrode 12, and integrates the charge for each application of the pulse. The capacitance detection means 17 detects a change in the capacitance of the detection electrode 12 based on the integral value of this charge.

[0031] The input terminal 15 is not necessarily limited to a connecting member such as a metal fitting, but may be at least a part of a conductor (such as a wire) that electrically connects the detection electrode 12 and the inside of the capacitance detection means 17.

[0032] The control unit 16 controls the detection of capacitance by the capacitance detection means 17. The control unit 16 also determines whether or not a human body is seated based on the detection result of the capacitance detection means 17, i.e., the capacitance of the detection electrode 12. In a self-capacitance type sensor, as described above, the capacitance of the detection electrode 12 is larger when a human body is seated than when a human body is not seated. In this case, the control unit 16 determines that a human body is seated when, for example, the integral value of the charge detected by the capacitance detection means 17 exceeds a threshold value, and determines that a human body is not seated when, for example, the integral value of the charge detected by the capacitance detection means 17 does not exceed the threshold value. The control unit 16 can be implemented using a circuit such as a microcomputer.

[0033] The overvoltage detection means 11 is electrically connected to the input terminal 15 of the capacitance detection means 17. The voltage of the input terminal 15 is input to the overvoltage detection means 11. As a result, the overvoltage detection means 11 detects an overvoltage at the input terminal 15. In other words, the overvoltage detection means 11 detects whether or not the voltage of the input terminal 15 has reached a predetermined voltage. In addition, the overvoltage detection means 11 is electrically connected to the capacitance detection means 17 via the off-delay means 19.

[0034] When an overvoltage is detected by the overvoltage detection means 11, a signal corresponding to the detection of the overvoltage is input to the capacitance detection means 17 via the off-delay means 19. Then, the capacitance detection means 17 temporarily suspends the detection of the capacitance of the detection electrode 12, and then resumes the detection of the capacitance of the detection electrode 12.

[0035] For example, electrical noise may occur in the detection circuit 14. An overvoltage may occur at the input terminal 15 due to the noise. As described later, such noise may be, for example, noise occurring in the power line of the human body detection sensor 10. However, the noise in the embodiment is not necessarily limited to noise from the power line. If noise (overvoltage) occurs at the input terminal 15 and a current caused by the noise flows from the input terminal 15 to the capacitance detection means 17, a large error may occur in the detection result (i.e., the integral value) of the capacitance detection means 17. Therefore, the noise may cause erroneous detection of the human body. In other words, an overvoltage means a voltage that is so excessive that it causes erroneous detection of the human body, and not only the positive side but also the negative side voltage fluctuations become overvoltage. To give a specific numerical value, the overvoltage detection means 11 detects both a voltage of +50V or more and a voltage of -50V or less as an overvoltage.

[0036] In contrast, in the detection circuit 14, as described above, when the overvoltage detection means 11 detects an overvoltage, the capacitance detection means 17 temporarily suspends and then resumes the detection of capacitance. As a result, even if an overvoltage occurs at the input terminal due to noise from a power supply, for example, the capacitance detection means temporarily suspends the detection of capacitance, thereby preventing erroneous detection due to noise.

[0037] In detecting the capacitance of the detection electrode 12, the charge accumulated in the capacitance C1 is input to a charge amount measuring section (e.g., an integrating means described later) of the capacitance detection means 17 via the input terminal 15. For example, as described later, the capacitance detection means 17 is provided with a switch. By periodically turning the switch on and off, the transmission of a pulse signal to the detection electrode 12 and the integration of the charge for each application of a pulse are periodically repeated. In this case, pausing the detection of the capacitance of the detection electrode 12 corresponds to, for example, pausing the periodic on / off of the switch. Furthermore, resuming the detection of the capacitance of the detection electrode 12 corresponds to resuming the periodic on / off of the switch.

[0038] The off-delay means 19 is electrically connected to the overvoltage detection means 11 and the capacitance detection means 17. The off-delay means 19 is a circuit for causing the capacitance detection means 17 to maintain a state in which the detection of capacitance is temporarily suspended for a predetermined time. When the off-delay means 19 receives a signal corresponding to the detection of an overvoltage from the overvoltage detection means 11, it transmits a signal to the capacitance detection means 17. In response to the signal from the off-delay means 19, the capacitance detection means 17 maintains a state in which the detection of capacitance is temporarily suspended for a predetermined time. The length of time for which the detection of capacitance is temporarily suspended can be adjusted by the output of the off-delay means 19.

[0039] For example, noise occurring in the detection circuit 14 may continue to occur at the input terminal 15. Even in such a case, the off-delay means 19 continues the state in which the detection of the capacitance is temporarily stopped, thereby suppressing the effect of the noise on the detection result of the capacitance detection means 17. Note that the off-delay means 19 is not necessarily provided in the embodiment.

[0040] A specific example of the toilet seat device 110 and the human body detection sensor 10 will be described below, taking as an example a case in which the detection electrode 12 is a thermal diffusion sheet for diffusing heat from a heater provided on the toilet seat.

[0041] FIG. 3 is a cross-sectional view that diagrammatically illustrates a portion of the toilet seat according to the embodiment. FIG. 3 is a schematic cross-sectional view taken along line A1-A2 in FIG. As shown in FIG. 3, the toilet seat 114 has an internal space SP. In other words, the toilet seat 114 is hollow. The toilet seat 114 has, for example, an upper plate 130 and a lower plate 132, and the upper plate 130 and the lower plate 132 are joined together to form an internal space SP between the upper plate 130 and the lower plate 132. The upper plate 130 has a seating surface 130a on which a user sits, and an inner surface 130b that faces the lower plate 132. In other words, the inner surface 130b is a surface (the underside of the toilet seat 114) that faces the opposite side to the seating surface 130a in the internal space SP. The upper plate 130 and the lower plate 132 may be joined together by adhesion using an adhesive, or by welding using vibration welding or the like. However, the configuration of the toilet seat 114 is not limited to the above, and may be any configuration having at least an internal space SP, a seating surface 130a, and an inner surface 130b.

[0042] FIG. 4 is a plan view that illustrates the toilet seat according to the embodiment. FIG. 5 is a partial cross-sectional view that diagrammatically illustrates a portion of the toilet seat according to the embodiment. 4 and 5, the heater 204 is provided in the internal space SP, and heats the seating surface 130a from the inside via the inner surface 130b by applying an AC voltage from the outside. The heater 204 generates heat by passing an electric current through it. The heater 204 is, for example, a heating wire.

[0043] The detection electrode 12 is provided on the inner surface 130b. The detection electrode 12 is, for example, sheet-shaped. The heater 204 is, for example, cord-shaped. The area of ​​the detection electrode 12 is larger than the area of ​​the heater 204. As a result, the detection electrode 12 diffuses the heat of the heater 204 to the inner surface 130b. In this way, the detection electrode 12 is provided on the inner surface 130b, changes the capacitance depending on whether or not the toilet seat 114 is seated, has an area larger than that of the heater 204, and diffuses the heat of the heater 204 to the inner surface 130b. In other words, the detection electrode 12 functions as an electrode that detects whether or not the toilet seat 114 is seated, and also functions as a thermal diffusion sheet that diffuses the heat of the heater 204 to the inner surface 130b.

[0044] A first adhesive 240 is provided between the detection electrode 12 and the heater 204. The first adhesive 240 bonds the detection electrode 12 and the heater 204 together.

[0045] A second adhesive 242 is provided between the detection electrode 12 and the inner surface 130b of the upper plate 130. The second adhesive 242 bonds the detection electrode 12 and the inner surface 130b of the upper plate 130. As a result, the detection electrode 12 is provided on the inner surface 130b of the upper plate 130.

[0046] The detection electrode 12 is a conductor. The detection electrode 12 is, for example, a metal foil. The thermal conductivity of the metal foil is higher than the thermal conductivity of the upper plate 130, which is generally made of resin. The detection electrode 12 is, for example, an aluminum foil or a copper foil.

[0047] As shown in FIG. 4, the heater 204 meanders on the detection electrode 12 and is disposed over substantially the entirety (whole circumference) of the detection electrode 12. The detection electrode 12 is also provided over substantially the entirety (whole circumference) of the inner surface 130b of the upper plate 130. The heater 204 meanders under the inner surface 130b of the upper plate 130 and is disposed over substantially the entirety of the inner surface 130b. In this manner, the cord-shaped heater 204 is provided on the inner surface 130b while being bent. The heater 204 is not limited to being cord-shaped, and may be sheet-shaped or the like. The heater 204 may have any configuration that can heat the seating surface 130a from the inside.

[0048] FIG. 6 is a block diagram that diagrammatically illustrates a toilet seat device according to an embodiment. As shown in FIG. 6, the toilet seat device 110 has a power supply circuit 18 (switching power supply circuit). The power supply circuit 18 is electrically connected to an AC power supply PS via a coil 38 and a power supply terminal 30. The power supply circuit 18 converts AC power supplied from the AC power supply PS into DC power, and supplies the converted DC power to the detection circuit 14 and the control unit 16. The detection circuit 14 and the control unit 16 operate based on the supply of DC power from the power supply circuit 18. The AC power supply PS is, for example, a commercial power supply of AC 100V (effective value). The power supply terminal 30 is, for example, an outlet plug. The power supply circuit 18 is, for example, an insulated AC / DC converter. A varistor 60 is provided between the ground side 30a and the non-ground side 30b of the power supply terminal 30. A varistor 61 is provided between the ground side 30a of the power supply terminal 30 and a common potential GND.

[0049] The power supply circuit 18 includes, for example, a rectifier circuit 31, a smoothing capacitor 32, and a conversion circuit 33. The rectifier circuit 31 rectifies the AC voltage supplied from the AC power supply PS and converts it into a pulsating rectified voltage. The rectifier circuit 31 is, for example, a full-wave rectifier using a diode bridge, and converts the AC voltage into a full-wave rectified voltage. The rectifier circuit 31 may be, for example, a half-wave rectifier.

[0050] The smoothing capacitor 32 smoothes the rectified voltage rectified by the rectifier circuit 31, and converts the rectified voltage into a DC voltage.

[0051] The conversion circuit 33 converts the DC voltage converted by the smoothing capacitor 32 into DC power compatible with the detection circuit 14 and the control unit 16. The conversion circuit 33 is a so-called DC-DC converter. The conversion circuit 33 converts, for example, a DC voltage of 100V into a DC voltage of about 5V to 24V. In other words, the conversion circuit 33 is a step-down converter. The conversion circuit 33 supplies the converted DC power to the detection circuit 14 and the control unit 16. This allows the detection circuit 14 and the control unit 16 to operate in response to the supply of DC power from the conversion circuit 33 (power supply circuit 18).

[0052] The conversion circuit 33 has a transformer 34 that electrically insulates the primary side (AC power supply PS side) from the secondary side (load side). In other words, the conversion circuit 33 electrically insulates the input side from the output side. The conversion circuit 33 is, for example, an insulating converter. The conversion circuit 33 is, for example, a flyback converter. However, the conversion circuit 33 does not necessarily have to be an insulating converter. The power supply circuit 18 may have any configuration that can convert AC power into DC power according to the detection circuit 14 and the control unit 16.

[0053] The coil 38 is, for example, a common mode choke coil for suppressing common mode noise. An end 38a of the coil 38 is electrically connected to one input terminal of the rectifier circuit 31. An end 38b of the coil 38 is electrically connected to the other input terminal of the rectifier circuit 31. An end 38c of the coil 38 is connected to a common potential GND via a varistor 61. An end 38d of the coil 38 is electrically connected to the non-grounded side 30b of the power supply terminal 30. The common potential GND is, for example, the potential of the earth (so-called earth). The common potential GND may be, for example, the potential of a conductive frame or chassis of the device (so-called frame ground or chassis ground).

[0054] The power supply circuit 18 further includes a capacitor 37. The capacitor 37 is provided between a common potential GND on the primary side of the conversion circuit 33 and a common potential GND on the secondary side of the conversion circuit 33. The capacitor 37 suppresses noise that is carried over to the GND on the secondary side due to the voltage conversion operation of the conversion circuit 33.

[0055] The toilet seat device 110 has a heater 204 that heats the toilet seat 114. The heater 204 is connected to a power supply terminal 30. As a result, an AC voltage supplied from an AC power supply PS is applied to the heater 204. In addition, a switching element 220 for switching between application and stop of the AC voltage to the heater 204 is provided between the heater 204 and the power supply terminal 30. For example, a phototriac can be used as the switching element 220. The switching element 220 is connected to the control unit 16. The control unit 16 controls the on / off switching of the switching element 220. In other words, the control unit 16 controls the supply of electricity to the heater 204 (application and stop of the AC voltage).

[0056] The control unit 16 controls the supply of electricity to the heater 204 so that the temperature of the seating surface 130a of the toilet seat 114 becomes a predetermined set temperature set by, for example, operating the operation unit 106. Furthermore, the control unit 16 sets the temperature of the seating surface 130a of the toilet seat 114 lower than the set temperature when, for example, the detection circuit 14 does not detect a seated person. Then, the control unit 16 raises the temperature of the seating surface 130a of the toilet seat 114 to the set temperature when the detection circuit 14 detects a seated person. This makes it possible to reduce unnecessary power consumption when the toilet seat device 110 is not in use, and to reduce the power consumption of the toilet seat device 110.

[0057] The control unit 16 controls the energization of the heater 204, for example, by a pattern control method in which multiple half-waves of the AC voltage are treated as one unit. The control unit 16 switches between energizing and stopping the energization of the heater 204, for example, according to the detection result of the zero-cross point. The control unit 202 increases the number of half-waves to be energized when, for example, increasing the temperature of the seating surface 130a, and decreases the number of half-waves to be energized when, for example, maintaining or lowering the temperature of the seating surface 130a. This allows the temperature of the seating surface 130a to be controlled to a desired temperature.

[0058] 4 and 5 is used for the detection electrode 12. A capacitance C1 is formed between the human body HB and the heat diffusion sheet (detection electrode 12) provided on the toilet seat 114. The capacitance detection means 17 detects the capacitance C1.

[0059] The capacitance detection means 17 includes, for example, a switch section 20, a charge amount measurement section 22, a protective resistor 42, and a varistor 44. The switch section 20 functions, for example, as a pulse output section. That is, the switch section 20 transmits a pulse signal to the detection electrode 12 based on an input from the control section 16. The charge amount measurement section 22 measures the capacitance of the detection electrode 12 based on the charge amount of the detection electrode 12 when the switch section 20 transmits a pulse signal to the detection electrode 12. The measured capacitance is input to the control section 16. For example, an integral value of the charge is input to the control section 16 as the capacitance of the detection electrode 12.

[0060] The switch section 20 has a first switch 71, a second switch 72, an inverter circuit 73, and an OR circuit 74. One of the input sides of the OR circuit 74 is connected to the control section 16. The output side of the OR circuit is connected to the first switch 71 and is connected to the second switch 72 via the inverter circuit 73. One end of the first switch 71 is connected to a predetermined voltage (power supply voltage VCC), and the other end of the first switch 71 is connected to one end of the second switch 72. The other end of the second switch 72 is connected to the charge amount measuring section 22 (integration means 52).

[0061] The charge amount measuring unit 22 has an integrating means 52 (capacitor), a transistor 54, a resistor 55, and a resistor 56. One end of the integrating means 52 is connected to the second switch 72, and the other end of the integrating means 52 is connected to the secondary side common potential GND. The base of the transistor 54 is connected to the control unit 16 via the resistor 55, and is also connected to the secondary side common potential GND via the resistor 56. The emitter of the transistor 54 is connected to the secondary side common potential GND. The collector of the transistor 54 is connected to the control unit 16, and is also connected between the second switch 72 and the integrating means 52.

[0062] One end of the protective resistor 42 is connected between the first switch 71 and the second switch 72. The other end of the protective resistor 42 is connected to the input terminal 15. In other words, the first switch 71 and the second switch 72 are electrically connected to the input terminal 15 via the protective resistor 42. For the first switch 71 and the second switch 72, for example, an analog switch or the like can be used. However, the first switch 71 and the second switch 72 are not limited to this, and any configuration that can switch between conductive and non-conductive can be used. The protective resistor 42 is a component that protects the capacitance detection means 17, which is composed of electronic components, from electrical stress that enters from the outside. The varistor 44 is connected between the common potential GND on the secondary side and the input terminal 15, and protects the capacitance detection means 17 from component destruction due to overvoltage or the like. A specific example of the overvoltage detection means 11 and the off-delay means 19 will be described later with reference to FIG.

[0063] Next, an example of the operation of the capacitance detection means 17 when no noise is occurring, that is, when no overvoltage is occurring at the input terminal 15, will be described with reference to FIGS.

[0064] Figures 7(a) to 7(d) and 8(a) to 8(c) are graphs that show an example of the operation of the detection circuit according to the embodiment. In these figures, the vertical axis represents the signal (voltage) and the horizontal axis represents the time. Figures 8(a), 8(b), and 8(c) show enlarged portions of Figures 7(b), 7(c), and 7(d), respectively.

[0065] 7(a), when detecting that the human body HB is seated, the control unit 16 first inputs a Hi signal to the base side of the transistor 54. That is, the signal S3 on the base side of the transistor 54 is set to Hi. This turns on the transistor 54, discharges the integrating means 52, and resets the signal S2 of the integrating means 52 to the secondary common potential GND as shown in FIG. 7(d).

[0066] 7(b), the control unit 16 periodically alternately inputs a Hi signal and a Lo signal to the switch unit 20. That is, the signal S1 on the input side of the switch unit 20 is periodically alternately set to Hi and Lo. When no overvoltage is detected at the input terminal 15, the output signal S6 of the OR circuit 74 is Hi when the signal S1 is Hi, and is Lo when the signal S1 is Lo.

[0067] The first switch 71 and the second switch 72 are turned on when a Hi signal is input, and turned off when a Lo signal is input. That is, the first switch 71 is on when the signal S1 is Hi, and turned off when the signal S1 is Lo. Conversely, the second switch 72 is off when the signal S1 is Hi, and turned on when the signal S1 is Lo. In this way, the capacitance detection means 17 performs a switching operation in which a first state in which the first switch 71 is on and the second switch 72 is off and a second state in which the first switch 71 is off and the second switch 72 is on are periodically alternately repeated in response to an input from the control unit 16.

[0068] In the first state, the detection electrode 12 is electrically connected to the power supply voltage VCC via the input terminal 15, the protective resistor 42, and the first switch 71. This causes charge to accumulate in the capacitance C1 of the detection electrode 12. In this manner, the first state is a state in which charge is accumulated in the capacitance C1 of the detection electrode 12. FIGS. 7(c) and 8(b) show a signal S100 at the input terminal 15, which corresponds to the potential of the detection electrode 12. For example, as shown in FIG. 8(b), the signal S100 is at a predetermined voltage (power supply voltage VCC in this example) immediately before times T1, T3, T5, and T7. In other words, the first state is a state in which the capacitance C1 of the detection electrode 12 is charged to a predetermined voltage.

[0069] On the other hand, in the second state, the detection electrode 12 is electrically connected to the integrating means 52 via the input terminal 15, the protective resistor 42, and the second switch 72. As a result, the charge accumulated in the capacitance C1 is input to the integrating means 52. In this way, the second state is a state in which the charge accumulated in the capacitance C1 of the detection electrode 12 is output to the integrating means 52. Therefore, as shown in FIG. 8(b), for example, the signal S100 drops from a predetermined potential between time T1 and time T2, between time T3 and time T4, and between time T5 and time T6. In other words, the second state is a state in which the capacitance C1 of the detection electrode 12 is discharged.

[0070] In this way, by the switching operation of switching the switch unit 20 between the first state and the second state at a predetermined frequency, a pulse signal corresponding to a predetermined voltage is input to the detection electrode 12, and the charge accumulated in the capacitance C1 is input to the integrating means 52. The frequency of the pulse signal can be changed according to the frequency of the signal S1. Also, the signal S100 has a dull waveform compared to the signal S1 due to the delay caused by the CR circuit such as the capacitance C1 and the protective resistor 42.

[0071] The integrating means 52 stores the charge discharged from the capacitance C1 of the detection electrode 12 in the second state that is repeated by the above switching operation. Therefore, as shown in Fig. 8(c), for example, the signal S2 output from the integrating means 52 increases in proportion to the number of times the first state and the second state are switched to, that is, the "number of integrations." For example, like the signal levels at times T1, T3, and T5, the signal S2 increases by a predetermined value each time the capacitance detection means 17 enters the second state.

[0072] Random noise called white noise occurs in electric circuits, but as the number of integrations increases, the random noise is averaged and the output of the integration circuit 50 becomes more stable. In other words, as the number of integrations increases, the signal amount increases and the noise decreases, resulting in a high S / N operation for the detection circuit 14.

[0073] In this way, the integrating means 52 integrates the charge of the capacitance C1 input at a predetermined frequency in response to the switching operation, and outputs the integral value to the control unit 16 as the detection result. The control unit 16 A / D converts the integral value and determines whether or not the human body HB is seated. The capacitance C1 in a state where the human body HB is present (a state where the human body is close to the detection electrode 12) is larger than the capacitance C1 in a state where the human body HB is not present (a state where the human body is not close to the detection electrode 12). Therefore, when switching between the first state and the second state is performed a predetermined number of times in a predetermined cycle and the charge of the capacitance C1 is integrated as described above, the integral value (amount of change) in a state where the human body HB is present is larger than the integral value in a state where the human body HB is not present.

[0074] The control unit 16 judges whether or not the human body HB is seated, based on the charge accumulated in the integrating means 52 (result of A / D conversion of the integral value). More specifically, for example, the control unit 16 sets the signal S2 (secondary side common potential GND in this example) after resetting the integrating means 52 as a reference value, and treats the amount of change in the signal S2 from the reference value after switching between the first state and the second state a predetermined number of times as an integral value (detection result of the electrostatic capacitance). The control unit 16 judges whether or not the human body HB is seated, based on this integral value. The number of times (number of pulses) the first state and the second state are switched is, for example, about 1000 times.

[0075] The capacitance detection means 17 repeatedly executes the operations shown in Fig. 7(a) to Fig. 7(d) at a predetermined cycle, whereby the control unit 16 repeatedly determines whether or not the human body HB is seated at the seat at the predetermined cycle, and as a result, seating detection can be performed continuously.

[0076] Next, an example of noise and false positives will be described. The inventors of the present application have found that in a conventional capacitance type seating sensor, if the area of ​​the detection electrode is increased, the influence of noise increases, and there is a risk that erroneous detection of the seating state may become more likely.

[0077] As described above, there is a method of using a thermal diffusion sheet with a larger area than the heater as the detection electrode 12. The thermal diffusion sheet is strongly thermally coupled to the heater in the toilet seat. The thermal diffusion sheet has the role of spreading the heat generated by the heater almost evenly over the entire toilet seat. For this reason, the thermal diffusion sheet is provided over a wide area in the toilet seat where a user may sit. Therefore, if the thermal diffusion sheet is used as the detection electrode, it is possible to prevent the user from missing the seat depending on where he or she sits. In addition, since there is no need to provide a detection electrode separate from the thermal diffusion sheet, it is preferable to use the thermal diffusion sheet as the detection electrode.

[0078] However, since the thermal diffusion sheet is strongly thermally coupled to the heater, the electrostatic coupling between the thermal diffusion sheet and the heater is also strong. This means that there is a risk of noise being transmitted from the heater to the thermal diffusion sheet, i.e., from the heater to the detection electrode. One example of this noise is noise from a commercial power source directly connected to the heater.

[0079] Also, the area of ​​the thermal diffusion sheet is as large as the seating area of ​​the toilet seat, for example. The large area of ​​the thermal diffusion sheet results in a large detection capacitance. According to experiments by the inventors of the present application, for example, the coupling capacitance between the heater and the thermal diffusion sheet is about 300 pF, which is constantly detected even when the user is not seated. Furthermore, when the user sits down, the human body adds about 100 pF to the detection capacitance, making the total detection capacitance about 400 pF. However, this is only when the user simply sits down on the toilet seat. If the user puts his / her bare feet on the floor or touches surrounding metal with his / her hands, the electrical coupling between the human body and the ground will be strengthened, and the detection capacitance will further increase. Therefore, the capacitance detection circuit may be required to have the performance to detect a capacitance of up to several hundred pF.

[0080] And, in the case of large-capacity electrostatic detection, there is a restriction on the measurement time. An example of this is described below. First, the detection capacitance is large because the area of ​​the detection electrode is large, and as a result, external noise is easily introduced into the detection electrode. Therefore, as an input protection means for the electrostatic capacitance detection circuit, it is possible to attach a protective resistor in series with the detection electrode. Also, there are several methods for electrostatic capacitance detection, and as described above, there is a method in which an AC pulse is applied to the detection electrode and the amount of charge flowing out or in at that time is measured. For example, if the area of ​​the detection electrode is wide and the detection capacitance is large, and a protective resistor is attached thereto, the time constant determined by the multiplication of the detection capacitance and the protective resistor becomes large. For example, the pulse width of the above-mentioned AC pulse is set to a sufficient time taking into account this time constant.

[0081] A trial calculation shows that if the detection capacitance is 400pF and the protective resistance is 10kΩ, the time constant is 4μs. Considering the CR transient phenomenon, for example, charging and discharging to about 99% of the final value is possible with 5 times the time constant, so if the Hi / Lo times of the AC pulse are 20μs each, the AC pulse period will be 40μs and the frequency will be 25kHz. It is also possible to improve the accuracy of capacitance measurement by repeatedly outputting AC pulses and measuring the charge. For example, if 1000 AC pulses are output for one capacitance measurement, the measurement time will be 40μs x 1000 times = 40ms.

[0082] A typical capacitance sensor is one that detects touch operations using a fingertip, for example. In this case, the detection capacitance is, for example, about 1 pF, so if calculated in the same way, the measurement time is 0.1 ms. In this way, in a capacitance-type seat sensor that uses the heat diffusion sheet of the toilet seat as the detection electrode, the measurement time can be orders of magnitude longer than that of a typical capacitance sensor.

[0083] Let's take the example of "noise from commercial power sources" mentioned above. A typical method of power control is "phase control." This controls the switching element thyristors from off to on and on to off at any phase of the AC power waveform, allowing the load to conduct for any length of time. This control is performed for every half-wave of the AC power supply. During this process, there is a sudden current fluctuation, which generates a short-lasting high-frequency clicking noise on the power line. In other words, the noise generated when the thyristors turn on is superimposed on every half-wave of the power supply waveform. If the commercial power supply frequency is 50Hz, noise occurs every 10ms.

[0084] Because the capacitance measurement time mentioned above was 40 ms, if a device that performs phase control is connected to the same power line, noise will be introduced multiple times during one measurement. Noise voltage can be as high as 1 kV, for example, and if such a voltage is introduced into the capacitance detection circuit during measurement, the measurement results will fluctuate significantly, and there is a risk of false detection of the seating state.

[0085] For example, as a means for suppressing such false detection, a method of attaching a sensor equivalent to the above-mentioned "capacitive sensor for detecting fingertip touch operation" to a part of the toilet seat and detecting seating in a small area of ​​about the size of a fingertip is conceivable. In this case, since the detection capacitance is small, for example, about 1 pF, the measurement time is short, and seating detection can be performed while avoiding noise that occurs in a cycle of about 10 ms. For example, it is possible to complete capacitance detection in the time between one noise and the next noise. However, since the detection area is small, the detection range is limited to a narrow area. Therefore, false detection may occur depending on the user's seating position.

[0086] Another method to suppress false positives is to discard the measurement data when noise is detected during measurement. However, if the measurement time is long or noise occurs in short cycles, most of the measurement data will be discarded because noise occurs frequently during one measurement, making it impossible to detect seating.

[0087] As described above, in a toilet seat having a thermal diffusion sheet, if the thermal diffusion sheet of the toilet seat is used as a detection electrode, the seating detection range can be widened without providing a new detection electrode, and false detection due to the seating position can be suppressed. On the other hand, if the detection area (electrode) is made larger, the detection capacity increases, and the charging and discharging time of the detection electrode becomes longer, and the measurement time becomes longer. If the measurement time becomes longer, the influence of noise on the measurement result may become greater. For example, it becomes difficult to avoid the influence of power supply noise that occurs in a short cycle (for example, noise that occurs at twice the frequency of the power supply frequency due to phase control). Therefore, it is desired to suppress false detection due to noise while widening the seating detection area of ​​the toilet seat.

[0088] For example, as indicated by an arrow AR1 in Fig. 6, noise is transmitted from the power supply terminal 30 to the input terminal 15 via the capacitance C2 between the heater 204 and the detection electrode 12. Furthermore, as indicated by an arrow AR2 in Fig. 6, the noise is transmitted from the input terminal 15 to the common potential GND on the secondary side via the capacitance detection means 17, transmitted to the common potential GND on the primary side via the capacitor 37 of the power supply circuit 18, and then passes through the coil 38 to the ground potential. For example, the capacitor 37 and the coil 38 are present on the path of the noise entering from the detection electrode 12 to the ground, and may affect seating detection.

[0089] An example of the effect of noise on seating detection will be described with reference to FIG. 9, FIGS. 10(a) to 10(d), and FIGS. 11(a) to 11(c). FIG. 9 is a schematic block diagram showing a toilet seat apparatus according to a reference example. Fig. 9 shows a human body detection sensor 910 provided in a toilet seat device of a reference example. In the human body detection sensor 910 of the reference example, an overvoltage detection means and an off-delay means are not provided. In addition, the OR circuit 74 is not provided. Other than this, the configuration of the toilet seat device of the reference example is the same as that of the toilet seat device described with reference to Fig. 6 etc. In the reference example as well, a thermal diffusion sheet of a heater is used for the detection electrode.

[0090] Fig. 10(a) to Fig. 10(d) and Fig. 11(a) to Fig. 11(c) are graphs that show an example of the operation of the detection circuit according to the reference example. These figures show the case where an overvoltage occurs at the input terminal in the seating detection by the human body detection sensor 910 shown in Fig. 9. In these figures, the vertical axis shows the signal (voltage) and the horizontal axis shows the time. Fig. 11(a), Fig. 11(b), and Fig. 11(c) show enlarged parts of Fig. 10(b), Fig. 10(c), and Fig. 10(d), respectively.

[0091] As shown in Fig. 10(b), a pulse signal is sent to the detection capacitance by alternately turning on and off the two switches. As a result, the detection capacitance is repeatedly charged and discharged, as shown in the input terminal waveform in Fig. 10(c), and the output potential of the integrating means rises, as shown in Fig. 10(d).

[0092] During the integral operation, noise may occur, causing the voltage at the input terminal to fluctuate significantly as shown in FIG. 10(c). For example, as shown between time T15 and time T17 in FIG. 11(b), when the input terminal is in a state (second state) where it is conductive with the integrating means via the protective resistor and the second switch, noise that oscillates significantly occurs in the voltage at the input terminal. If the capacitance detection means is in the second state when an overvoltage (noise) occurs at the input terminal, charges caused by the noise are accumulated in the integrating means, and the charges cause errors in the detection result (integral value). This may result in erroneous detection of the human body.

[0093] For example, the peak value of momentary noise (e.g. one pulse at time T16 in Figure 11(b)) is about 1 kV, and the pulse width is about 1 μs. The peak value can be suppressed to a certain voltage by the varistor at the input terminal. Even so, depending on the selection of the varistor, the peak value can become several tens of volts or more. The momentary noise enters the heat diffusion sheet from the heater via capacitive coupling. In other words, the noise at the input terminal becomes an AC signal via the capacitor, and so the noise enters both positive and negative.

[0094] The energy of the instantaneous noise passes through the circuit of the toilet seat device and escapes to the ground. At that time, the voltage at the input terminal oscillates due to the capacitance component of the capacitor in the power supply circuit of the toilet seat device and the induction component of the coil. For example, when observing the waveform in detail between time T16 and time T17 in FIG. 11(b), after the instantaneous noise is introduced, the secondary side where the detection circuit is located fluctuates with a time delay. Since the secondary circuit has a resistive coupling with the ground due to loads such as valves and nozzles (not shown), the oscillation is attenuated and disappears. Depending on the state of the toilet seat device, the time is, for example, several μs to several tens of μs. This time is longer than the time during which the instantaneous noise is applied (for example, about 1 μs). Therefore, even if the noise voltage is relatively suppressed by the varistor connected to the input terminal, the error in the detection result (integral value) becomes large because it corresponds to the product of the oscillating voltage and time, as shown in FIG. 10(d) and FIG. 11(c).

[0095] As explained above, even if the noise is momentary, if the noise voltage is large, the error in the integrated value will be large. Furthermore, even if the noise voltage is not extremely large, if it takes a long time for the voltage to decay, the error in the integrated value will be large.

[0096] In contrast, in the embodiment, as described above, the overvoltage detection means 11 is provided. When the overvoltage detection means 11 detects an overvoltage, the capacitance detection means 17 temporarily stops detecting the capacitance and then resumes it. This makes it possible to suppress erroneous detection due to noise while widening the seating detection area of ​​the toilet seat. An example of the overvoltage detection means 11, the off-delay means 19, and the detection operation will be described with reference to Fig. 12, Figs. 13(a) to (g), and Figs. 14(a) to (f).

[0097] FIG. 12 is a block diagram illustrating a specific example of a human body detection sensor according to the embodiment. The detection circuit 14 shown in Fig. 12 is an example of the detection circuit 14 of the human body detection sensor 10 described with reference to Fig. 6. As shown in Fig. 12, the overvoltage detection means 11 has diodes 80 and 89, Zener diodes 81 and 82, transistors 83 and 84, and resistors 85, 86, 87, and 88.

[0098] The anode side of the diode 80 is electrically connected to the input terminal 15, and the cathode side of the diode 80 is electrically connected to the cathode side of a Zener diode 81. The anode side of the Zener diode 81 is electrically connected to the base of a transistor 84 via a resistor 87. In the transistor 84, the emitter is connected to the secondary common potential GND, and a resistor 88 is connected between the emitter and the base. The collector of the transistor 84 is electrically connected to the off-delay means 19.

[0099] The cathode side of the diode 89 is electrically connected to the input terminal 15, and the anode side of the diode 89 is electrically connected to the anode side of the Zener diode 82. The cathode side of the Zener diode 82 is electrically connected to the base of the transistor 83 via a resistor 86. In the transistor 83, the emitter is connected to the power supply voltage VCC, and a resistor 85 is connected between the emitter and the base. The collector of the transistor 83 is electrically connected to the base of the transistor 84 via a resistor 87.

[0100] The off-delay means 19 has a resistor 91, a capacitor 93, and an inverter circuit 95. One end of the resistor 91 is electrically connected to the power supply voltage VCC, and the other end of the resistor 91 is connected to the secondary common potential GND via the capacitor 93. The collector of the transistor 84 is electrically connected between the resistor 91 and the capacitor 93. As a result, the output signal of the overvoltage detection means 11 is input between the resistor 91 and the capacitor 93. The input side of the inverter circuit 95 is electrically connected between the resistor 91 and the capacitor 93, and the output side of the inverter circuit 95 is electrically connected to the input side of the OR circuit 74.

[0101] For example, the Zener voltage Vz1 of the Zener diode 81 and the Zener voltage Vz2 of the Zener diode 82 are each selected to have a value smaller than the protection voltage Vp of the varistor 44. Note that in the embodiment, the varistor 44 and the protection resistor 42 do not necessarily have to be provided, and are provided as necessary.

[0102] Fig. 13(a) to Fig. 13(g) and Fig. 14(a) to Fig. 14(f) are graphs that show an example of the operation of the detection circuit according to the embodiment. These figures show the case where an overvoltage (noise) occurs at the input terminal 15 in the seating detection by the human body detection sensor 10 shown in Fig. 12. In these figures, the vertical axis shows the signal (voltage) and the horizontal axis shows the time. Fig. 14(a), Fig. 14(b), Fig. 14(c), Fig. 14(d), Fig. 14(e), and Fig. 14(f) show enlarged parts of Fig. 13(b), Fig. 13(c), Fig. 13(d), Fig. 13(e), Fig. 13(f), and Fig. 13(g), respectively.

[0103] As shown in FIG. 13(a), when detecting the seating of the human body HB, the control unit 16 first sets the signal S3 on the base side of the transistor 54 to Hi. This resets the signal of the integrating means 52. Thereafter, as shown in FIG. 13(b), a switching operation is performed in which the first state and the second state are periodically alternately repeated. Then, charging and discharging of the capacitance C1 are alternately repeated, and the waveform of the input terminal 15 oscillates as shown in FIG. 13(c). Accordingly, the integrating means integrates the charge discharged from the capacitance C1, and as shown in FIG. 13(g), the change in the signal S2 from the reference value becomes large.

[0104] In such an integral operation, the voltage at the input terminal may fluctuate significantly as shown in Fig. 13(c). For example, as shown in Fig. 14(b), at time T26, instantaneous noise is input to input terminal 15. Then, between time T26 and time T27, the noise at input terminal 15 oscillates and attenuates.

[0105] For example, when a positive overvoltage occurs at the input terminal 15, as shown in FIG. 13(d) and FIG. 14(c), the signal S4 on the base side of the transistor 84 changes from Lo to Hi. For example, a pulse occurs in the signal S4. In this way, the overvoltage detection means 11 detects an overvoltage at the input terminal 15. The overvoltage detection in the overvoltage detection means 11 operates when the overvoltage exceeds the Zener voltage of the Zener diode. More specifically, in the case of a positive overvoltage, when the voltage of the input terminal 15 exceeds a predetermined value (Vf1+Vz1+Vbe1), the overvoltage is detected. Here, Vf1 is the forward voltage of the diode 80, Vz1 is the Zener voltage of the Zener diode 81, and Vbe1 is the base-emitter voltage of the transistor 84. In the case of a negative overvoltage, when the voltage of the input terminal 15 falls below a predetermined value (VCC-Vbe2-Vz2-Vf2), the overvoltage is detected. Here, VCC is the power supply voltage, Vbe2 is the base-emitter voltage of transistor 83, Vz2 is the Zener voltage of Zener diode 82, and Vf2 is the forward voltage of diode 89. The predetermined value (overvoltage) detected by overvoltage detection means 11 may be appropriately determined so as to suppress erroneous detection, taking into consideration the magnitude of error that noise may cause in the detection result.

[0106] When the overvoltage detection means 11 detects a positive or negative overvoltage, the capacitor 93 of the off-delay means 19 is discharged. This causes the voltage on the input side of the inverter circuit 95 to fluctuate, and as shown in Fig. 13(e) and Fig. 14(d), the signal S5 on the output side of the inverter circuit 95 goes from Lo to Hi. For example, a pulse is generated in the signal S5. The width of this pulse corresponds to the CR time constant of the capacitor 93 and resistor 91.

[0107] The output of the off-delay means 19, i.e., the signal S5, is input to the OR circuit 74. Therefore, when the signal S5 is Hi, the output (signal S6) of the OR circuit 74 becomes Hi regardless of the input (signal S1) from the control unit 16. This causes the capacitance detection means 17 to enter the first state in which the first switch 71 is on and the second switch 72 is off. In other words, when an overvoltage is detected, the capacitance detection means 17 is forced to enter the first state.

[0108] This first state continues while the signal S5 is Hi. In the first state, the second switch 72 is off, so that no charge is integrated in the integrating means 52, and no noise is integrated at the input terminal 15. Therefore, for example, as shown in FIG. 14(f), the signal S2 does not change between time T26 and time T27.

[0109] Furthermore, since the first switch 71 is on, the input terminal 15 is connected to the power supply voltage VCC, and so noise is more likely to escape to a power supply with low impedance. In other words, in order to prevent noise from being integrated, it is sufficient to simply forcibly turn off the second switch 72 when an overvoltage is detected, and when such control is performed, a state in which both the first switch 71 and the second switch 72 are off (so to speak, a third state) may occur, but since the first switch 71 is on in the first state, noise is more likely to attenuate quickly compared to when both are off.

[0110] Thereafter, when the signal S5 changes from Hi to Lo again, the output (signal S6) of the OR circuit 74 again periodically repeats Hi and Lo in response to the signal S1. That is, the capacitance detection means 17 resumes the switching operation based on the input from the control unit 16.

[0111] Thus, in the embodiment, the integral operation is paused at the moment when noise is input to the input terminal 15 and for a predetermined time immediately thereafter. This predetermined time can be adjusted, for example, by the pulse width of the signal S5. As shown in Fig. 14(c) and Fig. 14(d), the pulse of the signal S5 is longer than the pulse of the signal S4. For example, the pulse width of the signal S5 is determined so that the signal S5 is Hi until the noise at the input terminal 15 oscillates and attenuates to a small level after time T26 in Fig. 14(b). For example, the pulse width of the signal S5 is 10 μs or more and 100 μs or less.

[0112] Even if the noise oscillates in a damped manner due to the capacitive or inductive components of the power supply circuit, the off-delay means 19 can wait for the restart of the integration operation until the noise becomes small. For example, by temporarily suspending the switching operation, the duration of the first state becomes longer than the duration of the periodic first state caused by the switching operation. That is, for example, in the example of FIG. 14(e), the duration of the first state from time T26 to time T28 is longer than the duration of the first state from time T24 to time T25. In the embodiment, the integration is suspended at the moment when the noise enters and for the voltage fluctuation thereafter, so that it is possible to suppress the noise from being integrated and causing a large error.

[0113] At this time, depending on the timing of the noise and the signal S1, the original signal (the charge of the capacitance C1) may not be integrated. In that case, the integral value of one switching operation (the amount of change in the signal S2 due to one charging and discharging of the capacitance C1) will be an error, but if one measurement capacitance is integrated with, for example, 1000 switching operations, the effect is only 0.1%. In the human body detection sensor according to the reference example of FIG. 9, the error due to noise may be several percent, so by interrupting the integration operation and not integrating the noise as in the embodiment, it is possible to suppress the occurrence of a large error. Therefore, it is possible to suppress the occurrence of erroneous detection of a human body due to noise.

[0114] As described above, in the embodiment, when the overvoltage detection means 11 detects an overvoltage at the input terminal 15, the capacitance detection means 17 suspends the switching operation of alternately repeating the first state and the second state, and sets the first switch 71 and the second switch 72 to the first state. After that, the capacitance detection means 17 resumes the switching operation. According to such a configuration, when an overvoltage occurs at the input terminal 15 due to noise from a power supply or the like, the capacitance detection means 17 temporarily suspends the switching operation and enters the first state, so that the integration (accumulation of charge) of the integrating means is interrupted, thereby making it possible to prevent a large error in the integral value caused by noise. Therefore, it is possible to prevent erroneous detection caused by noise.

[0115] Furthermore, when the overvoltage detection means 11 detects an overvoltage, the off-delay means 19 causes the capacitance detection means 17 to continue in the first state for a predetermined time. According to this configuration, the first state continues, and thus the integration by the integrating means continues to be suspended, so that it is possible to further prevent erroneous detection caused by noise. For example, application of an overvoltage (noise) may cause a potential fluctuation in the reference voltage (secondary GND) of the circuit of the toilet seat device. At this time, for example, due to the inclusion of a capacitive component or an inductive component in the circuit of the toilet seat device, the state in which the potential fluctuation occurs in the input terminal may continue. This potential fluctuation may cause a large error in the capacitance detection. That is, since the circuit of the toilet seat device has a capacitive component and an inductive component, even if the applied overvoltage is instantaneous, the potential fluctuation due to the noise does not immediately become zero, and it takes a certain amount of time to converge. In contrast, according to the embodiment, the off-delay means continues the first state for a predetermined time, so that the interruption of the integration by the integrating means continues, and the time until the potential fluctuation due to the noise converges is secured, and it is possible to suppress the occurrence of a large error due to the noise in the integral value. Therefore, it is possible to further suppress the occurrence of erroneous detection due to noise.

[0116] As already mentioned, when a thermal diffusion sheet is used for the detection electrode 12, the area of ​​the detection electrode 12 is large, so that the seating detection range is widened, and erroneous detection due to the seating position can be suppressed. On the other hand, when the detection electrode 12 is large, the capacitance of the detection electrode 12 is large, so that the charging and discharging time is long, and the time required for capacitance detection is long. Therefore, during capacitance detection, the frequency of overvoltage occurring at the input terminal 15 due to noise (such as short-period noise on the power line, etc.) increases. Even in such a case, the capacitance detection means 17 temporarily stops detecting the capacitance, so that erroneous detection due to noise can be suppressed. Therefore, it is possible to suppress erroneous detection due to noise while widening the seating detection range.

[0117] In the embodiment, the noise detected by the overvoltage detection means is not necessarily limited to noise caused by the power supply as described above, but may be any noise that generates an overvoltage at the input terminal 15.

[0118] In addition, the detection electrode 12 is not limited to the thermal diffusion sheet of the heater 204, and may be provided separately from the thermal diffusion sheet. The thermal diffusion sheet is, for example, a metal foil arranged over almost the entire inner surface 130b of the toilet seat 114, and diffuses the heat of the heater 204 to the inner surface 130b. In this case, the detection electrode 12 can be arranged on the inner surface 130b of the toilet seat 114. For example, the detection electrode 12 may be overlapped on the thermal diffusion sheet or overlapped under the thermal diffusion sheet. In either arrangement, the thermal diffusion sheet, which is a metal, is electrostatically coupled to the human body and also to the detection electrode 12, so that it is possible to measure the capacitance between the detection electrode 12 and the human body via the thermal diffusion sheet. Alternatively, only the portion of the thermal diffusion sheet that overlaps with the detection electrode 12 may be cut out to eliminate the electrostatic effect of the thermal diffusion sheet. In this case, the area of ​​the detection electrode 12 may be smaller than the area of ​​the thermal diffusion sheet 250. Also, the arrangement of the detection electrode 12 does not necessarily have to be on the inner surface 130b. The sensing electrode 12 may be disposed at any position that allows proper detection of a human body sitting on the toilet seat 114 .

[0119] Furthermore, the human body detection sensor according to the embodiment is not limited to the self-capacitance type as described above, but may be a mutual capacitance type. In a mutual capacitance type capacitive sensor, the detection electrode has a transmitting electrode and a receiving electrode. The detection circuit is electrically connected to the transmitting electrode and the receiving electrode. Since the electric field around the detection electrode changes depending on the presence or absence of a human body, the amount of charge received by the receiving electrode changes when a pulse signal of a predetermined frequency is transmitted to the transmitting electrode. The detection circuit measures the amount of charge received by the receiving electrode as the capacitance of the detection electrode. The presence or absence of a human body can be determined based on the change in capacitance.

[0120] FIG. 15 is a block diagram that diagrammatically illustrates another toilet seat device according to an embodiment. The toilet seat device 111 shown in Fig. 15 has a detection circuit 14b instead of the above-mentioned detection circuit 14. As will be described later, the toilet seat device 111 differs from the above-mentioned toilet seat device 110 in the switching operation by the capacitance detection means 17b of the detection circuit 14b and the operation of the control unit 16. Other than this, the same explanation as for the toilet seat device 110 can be applied to the explanation of the configuration of the toilet seat device 111.

[0121] The detection circuit 14b does not include the overvoltage detection means 11 and the off-delay means 19. Moreover, the detection circuit 14b has a capacitance detection means 17b instead of the capacitance detection means 17. The capacitance detection means 17b does not include an OR circuit 74, unlike the capacitance detection means 17. In the capacitance detection means 17b, the signal S1 becomes an input signal to the switch 71 and the inverter circuit 73. Other than this, the same description as for the detection circuit 14 can be applied to the description of the configuration of the detection circuit 14b.

[0122] That is, the toilet seat device 111 has a toilet seat 114, a detection electrode 12, a capacitance detection means 17b, and a control unit 16. The detection electrode 12 changes in capacitance C1 in response to a human body sitting on the toilet seat 114. The capacitance detection means 17b is electrically connected to the detection electrode 12, and detects the change in capacitance C1 of the detection electrode 12. The control unit 16 determines whether or not a human body is sitting on the toilet seat based on the detection result (integral value) of the capacitance detection means. Note that, like the detection circuit 14, the detection circuit 14b is also provided with an overvoltage detection means 11, an off-delay means 19, and an OR circuit 74, and the detection of the capacitance may be temporarily stopped or resumed.

[0123] The capacitance detection means 17b includes a first switch 71, a second switch 72, and an integrating means 52. As described above, the first and second switches 71 and 72 are analog switches including elements such as transistors. The first switch 71 connects a predetermined voltage (power supply voltage VCC) to the detection electrode 12. When the first switch 71 is turned on, the predetermined voltage is connected to the detection electrode 12, and when the first switch 71 is turned off, the predetermined voltage is not connected to the detection electrode 12. The second switch 72 connects the integrating means 52 to the detection electrode 12. When the second switch 72 is turned on, the integrating means 52 is connected to the detection electrode 12, and when the second switch 72 is turned off, the integrating means 52 is not connected to the detection electrode 12.

[0124] The capacitance detection means 17b detects a change in the capacitance C1 of the detection electrode 12 by a switching operation. The switching operation is an operation of alternately repeating a first state (charging) and a second state (discharging) at a predetermined frequency and transmitting a pulse signal of a predetermined frequency to the detection electrode 12. As described above, in the first state, the first switch 71 is on and the second switch 72 is off. In the first state, a pulse signal is transmitted to the detection electrode 12 to set the detection electrode 12 to a predetermined voltage, and the detection capacitance (capacitance C1 and capacitance C2) is charged. In the second state, the first switch 71 is off and the second switch 72 is on. In the second state, the detection capacitance is discharged. The integration means 52 stores the charge discharged from the detection electrode 12.

[0125] The capacitance detection means 17b can change the frequency of the switching operation that repeats the first state and the second state to a plurality of different frequencies. In other words, the capacitance detection means 17b can transmit a plurality of pulse signals with different frequencies to the detection electrode 12. The frequency of the switching operation, i.e., the frequency of the pulse signal, is the frequency of the signal S1 and is controlled by the control unit 16.

[0126] For example, the capacitance detection means 17b can switch the frequency of the switching operation between a first frequency and a second frequency different from the first frequency. In other words, there are a first switching operation of a first frequency and a second switching operation of a second frequency. The first switching operation repeats a first state and a second state at the first frequency by a signal S1 of the first frequency, and transmits a pulse signal at the first frequency. The first switching operation repeats the first state and the second state a predetermined number of times at the first frequency, that is, transmits a predetermined number of pulse signals at the first frequency, and detects a change in the capacitance C1. Similarly, the second switching operation repeats the first state and the second state a predetermined number of times at the second frequency, that is, transmits a predetermined number of pulse signals at the second frequency, and detects a change in the capacitance C1. Note that even if the frequency of the signal S1 is different, the charge accumulated in the integration means 52 will be equal as long as the predetermined number of repetitions is the same. That is, even if the frequency of the signal S1 is changed, there is no effect on the detection result of the capacitance in principle.

[0127] For example, the capacitance detection means 17b changes the frequency of the switching operation at a predetermined timing or at random timing. For example, the capacitance detection means 17b may alternately repeat a first switching operation and a second switching operation. However, this is not limited to this, and the frequency of the switching operation can be changed at an appropriate timing. In addition, the frequency of the switching operation may be three or more frequencies, not limited to two frequencies, the first frequency and the second frequency.

[0128] 16(a), 16(b), 17(a) and 17(b) are graphs that diagrammatically show the switching operation according to the embodiment. In these figures, the vertical axis represents the signal (voltage) and the horizontal axis represents the time. Figures 16(a) and 16(b) illustrate a first switching operation at a first frequency by the capacitance detection means 17b. Figures 17(a) and 17(b) illustrate a second switching operation at a second frequency by the capacitance detection means 17b.

[0129] Fig. 16(a) shows the signal S1 of the first frequency, and Fig. 16(b) shows the signal S100 when the signal S1 changes as in Fig. 16(a). Similarly, Fig. 17(a) shows the signal S1 of the second frequency, and Fig. 17(b) shows the signal S100 when the signal S1 changes as in Fig. 17(a). When the signal S1 is Hi, the capacitance detection means 17b is in the first state (charging), and when the signal S1 is Lo, the capacitance detection means 17b is in the second state (discharging).

[0130] In Figures 16(b) and 17(b), the solid line waveform is the waveform when damping vibration, which will be described later, occurs, and the dotted line waveform is the waveform when it is assumed that the damping vibration does not occur. In other words, the dotted line waveform is a waveform obtained by removing the influence of damping vibration, which will be described later, from the solid line waveform, and corresponds to, for example, an ideal waveform in terms of design. Note that, for the sake of convenience, this damping vibration is omitted in the explanations and graphs (e.g., Figures 8(b), 11(b), 14(b), etc.) relating to the toilet seat device 110 according to the above-mentioned embodiment and the toilet seat device according to the reference example.

[0131] 16(a), for example, at time T31, the capacitance detection means 17b switches from the second state to the first state. Then, the first state continues from time T31 to time T32. At time T32, the capacitance detection means 17b switches from the first state to the second state. Then, the second state continues from time T32 to time T33. In the first switching operation, the same operation from time T31 to time T33 is periodically repeated.

[0132] 17(a), for example, at time T41, the capacitance detection means 17b switches from the second state to the first state. Then, the first state continues from time T41 to time T42. At time T42, the capacitance detection means 17b switches from the first state to the second state. Then, the second state continues from time T42 to time T43. In the second switching operation, the same operation from time T41 to time T43 is periodically repeated.

[0133] As described above, the first frequency and the second frequency are different from each other. That is, the period P1 of the first switching operation (for example, from time T31 to time T33) is different from the period P2 of the second switching operation (for example, from time T41 to time T43). The period P2 is longer than the period P1.

[0134] When changing the frequency of the switching operation, the capacitance detection means 17b makes the time of one of the first state and the second state variable and fixes the time of the other of the first state and the second state. That is, the duration of one of the first state and the second state (hereinafter may be referred to as the "variable side") in the first switching operation is different from the duration of the variable side in the second switching operation, and the duration of the other of the first state and the second state (hereinafter may be referred to as the "fixed side") in the first switching operation is the same as the duration of the fixed side in the second switching operation.

[0135] For example, in this example, the time of the first state (charging) is variable, and the time of the second state (discharging) is fixed. More specifically, the duration P11 of the first state in the first switching operation shown in Fig. 16(a) (e.g., from time T31 to time T32) is shorter than the duration P21 of the first state in the second switching operation shown in Fig. 17(a) (e.g., from time T41 to time T42). On the other hand, the duration P12 of the second state in the first switching operation shown in Fig. 16(a) (e.g., from time T32 to time T33) is the same as the duration P22 of the second state in the second switching operation shown in Fig. 17(a) (e.g., from time T42 to time T43).

[0136] In the embodiment, when changing the frequency of the switching operation, the time of the first state may be fixed and the time of the second state may be variable. Furthermore, "fixed" time does not only mean that it does not change strictly, but also that it may change slightly within the range of variation (for example, variation due to characteristic changes over time of elements constituting the circuit).

[0137] By changing the frequency of the switching operation, it is possible to reduce errors that occur in the detection result of the capacitance due to noise of a specific frequency. On the other hand, for example, as shown in FIG. 16(b) and FIG. 17(b), when the first state and the second state are switched in the switching operation, the potential of the detection electrode may oscillate. For example, as described later, the circuit through which the current flows to charge and discharge the detection capacitance in the first state and the second state includes LCRs (inductors, capacitors, and resistors) connected in series with each other. Therefore, when the first state and the second state are switched, the potential of the detection electrode 12 may oscillate with damping according to the LCR. This damping oscillation occurs in the same way in both the first state and the second state. Here, when the frequency of the switching operation is changed, the influence of the vibration of the potential of the detection electrode on the detection result of the capacitance changes, and as a result, there is a risk of false detection of the presence or absence of a human body. In response to this, when the frequency of the switching operation is changed, the time of the other of the first state and the second state is fixed, so that the change in the influence of the vibration of the potential of the detection electrode due to the change in frequency can be reduced. This makes it possible to suppress the occurrence of false detection. This will be described below with reference to a specific example.

[0138] The detection electrode 12 is affected by noise present in the measurement environment. General noise is called white noise, which is random noise containing many frequency components. If charging and discharging operations, i.e., integration operations, are repeated at a constant frequency, the random noise and the timing of the integration operations vary and are not limited to a specific pattern, so the effect of the noise is averaged out by multiple integration operations, and ultimately (if the number of integration operations is large) the effect of the noise becomes substantially zero.

[0139] However, there are cases where noise has a specific frequency. For example, there are things that emit noise of a specific frequency depending on their operation, such as switching power supplies, motors, and wireless devices. When the noise frequency is synchronized with the charge / discharge frequency, that is, when there is an integer ratio relationship, the effect of the noise on the charge / discharge operation will be the same every time, and the effect of the noise will accumulate with repeated charging and discharging, causing a large error in the detection result (integral value), resulting in a false capacitance detection.

[0140] In such cases, one possible measure is to change the charge / discharge frequency (the frequency of the switching operation) so that the charge / discharge operation is not synchronized with the noise.The conditions for changing the charge / discharge frequency include randomly changing the charge / discharge frequency during the normal measurement stage (frequency burst), or measuring at a different charge / discharge frequency when the seated / not seated determination changes, and checking the results.

[0141] On the other hand, in this example, the charge and discharge operation of the capacitance detection circuit is performed through a path DL indicated by a dashed line in Fig. 15. The capacitance detection means 17b is on the secondary side, and the detection electrode 12 is electrostatically coupled with the heater 204; that is, before a human body sits down, there is already a large capacitance C2 in a non-seated state, and the capacitance detection means 17b charges and discharges this capacitance C2. Since charging and discharging are electrical operations, they form a closed circuit, and the path from the capacitance detection means 17b through the detection electrode 12, the heater 204, the power line 30a (including 30b when the switching element 220 is on), the coil 38 of the line filter, and the capacitor 37 between the primary and secondary, returning to the secondary GND, forms the charge and discharge circuit.

[0142] In this closed circuit, electrical elements such as a protective resistor 42, a coupling capacitance (capacitance C2) between the detection electrode 12 and the heater 204, a coil 38, and a capacitor 37 between the primary and secondary are connected in series. Here, the capacitor 37 between the primary and secondary is sufficiently larger than the capacitance C2 (for example, 10 times or more), so the capacitance (series capacitance) of the charge / discharge path is approximately equal to the capacitance C2. In other words, the capacitor 37 between the primary and secondary may be considered to be approximately short-circuited and excluded. Then, R of the protective resistor 42, C of the coupling capacitance (capacitance C2), and L of the line filter (coil 38) are connected in series, forming a circuit in which damped oscillation of LCR series resonance occurs. The charge / discharge operation is an operation in which a power supply voltage is alternately output as a pulse to the detection electrode 12 during charging, and an integrated voltage is alternately output as a pulse to the detection electrode 12 during discharging, so that the potential change causes damped oscillation of LCR resonance in the closed circuit of the charge / discharge operation. This oscillation becomes an error factor of the integrated value of the capacitance detection means.

[0143] In this way, the circuit that passes a current through the detection electrode 12 when charging or discharging includes an LCR series circuit. That is, the circuit through which the current that charges the detection capacitance in the first state and the current that discharges from the detection capacitance in the second state flows includes an inductor, a capacitor, and a resistor that are connected in series with each other. Therefore, damped oscillation may occur in the potential of the detection electrode 12 when switching from the first state to the second state or when switching from the second state to the first state.

[0144] In the embodiment, the charge / discharge path of the detection electrode 12 is not necessarily limited to the example in FIG. 15. The LCR connected to the charge / discharge path does not necessarily have to be the coil 38 of the line filter, the coupling capacitance (capacitance C2) of the detection electrode 12, and the protective resistor 42. In addition, the toilet seat device may have not only a toilet seat heating function but also a sanitary washing function, and an element of an electric load (motor, etc.) for that purpose may be added as a new LCR component. Therefore, the charge / discharge path of the detection electrode 12 includes a resistance component, an inductive component, and a capacitive component of the entire toilet seat device, and the potential of the detection electrode 12 undergoes damped oscillation at least during charging and discharging.

[0145] A specific example in which such potential oscillation becomes an error factor will be described. In detecting capacitance, the detection electrode 12 is charged with a constant voltage V, and a charge (Q=C×V) proportional to the capacitance C2 of the detection electrode 12 is accumulated, which is then discharged and integrated to convert into an electrical signal. For this reason, if the charging voltage V is not constant, for example, this does not work in principle, and fluctuations in the charging voltage V may result in detection errors in the capacitance detection means. The damping oscillation of the LCR changes the V portion of Q=C×V, and so is a cause of capacitance detection errors both during charging and discharging.

[0146] 18(a) and 18(b) are graphs that diagrammatically show an example of the operation of the detection circuit. Figures 18(a) and 18(b) show waveforms in which damping oscillation due to LCR occurs in the waveforms shown in Figures 8(a) and 8(b), with the time axis further expanded. In other words, the waveforms during charging and discharging may actually become like this.

[0147] As shown in Fig. 18(a), at time T51, the capacitance detection means switches from the second state to the first state. The first state continues from time T51 to time T52. At time T52, the capacitance detection means switches from the first state to the second state. The second state continues from time T52 to time T53.

[0148] In Fig. 18(b), if the voltage at the end of charging (for example, time T52) deviates from the original charging voltage (power supply voltage VCC) due to damped oscillation, this voltage difference ΔV becomes an error factor. In the case of Fig. 18(b), since the charging end voltage is lower than the power supply voltage VCC, the charging voltage of the detection electrode 12 becomes lower, the charge charged decreases, and the charge integrated during discharging also decreases, resulting in a smaller capacitance detection result. In other words, the oscillation component at the end of charging becomes a detection error.

[0149] Similarly, the oscillatory component is integrated during discharge. This is affected by the area IS during integration (voltage difference from the ideal waveform x time). If the sum of the areas IS is not zero for the ideal waveform as designed, an error will occur. As described above, the oscillatory component during integration becomes the detection error from the ideal value (when there is no vibration). Note that the ideal waveform and ideal value are the waveform and voltage value when there is no damped oscillation due to LCR. The area IS is the integral value obtained by integrating over time the difference between the waveform when there is no damped oscillation (dashed line) and the waveform when there is damped oscillation (solid line). During integration during discharge, the area IS becomes a factor of error. In other words, the integral value of the oscillatory component during the discharge period becomes the detection error.

[0150] The seating sensor (controller 16) determines that a person is seated when the capacitance C1 between the detection electrode 12 and the human body HB is added to the capacitance C2 between the detection electrode 12 and the heater 204, and the integral value changes. In other words, it is sufficient to determine that the detection capacitance increases relatively based on the capacitance C2, so even if there is a detection error, the effect on seating detection (seating determination) can be suppressed as long as the detection error is constant. In the first place, from the viewpoint of detecting the presence of a human body, the capacitance C2 itself is a fixed detection error.

[0151] Therefore, if the charge and discharge time is fixed, the influence of the damping oscillation due to LCR is fixed, and by treating this as a fixed offset component of the detected capacitance, it is possible to determine whether or not a person is seated.

[0152] If the charge / discharge time is constant, the effect of the damping vibration caused by the LCR can be fixed, but in order to avoid the effect of noise at a specific frequency as mentioned above, the charge / discharge time, i.e., the charge / discharge frequency, may be changed. This changes the effect of the damping vibration caused by the LCR, causing a difference in the capacitance detection result, which may result in an erroneous detection of the seating state.

[0153] 19(a) and 19(b) are graphs that diagrammatically show an example of the operation of the detection circuit. Figures 19(a) and 19(b) show the case where the charge / discharge time is shortened in Figures 18(a) and 18(b). That is, Figures 19(a) and 19(b) show the case where the charge / discharge frequency (the frequency of the switching operation) is increased, for example, for the purpose of noise reduction.

[0154] 19(a), at time T54, the capacitance detection means switches from the second state to the first state. The first state continues from time T54 to time T55. At time T55, the capacitance detection means switches from the first state to the second state. The second state continues from time T55 to time T56.

[0155] In the examples of Figures 18 and 19, when the charge / discharge frequency changes, both the time of the first state (charge time) and the time of the second state (discharge time) are variable. That is, the charge time (from time T54 to time T55) in Figure 19(a) is shorter than the charge time (from time T51 to time T52) in Figure 18(a). Also, the discharge time (from time T55 to time T56) in Figure 19(a) is shorter than the discharge time (from time T52 to time T53) in Figure 18(a).

[0156] As shown in FIG. 19(b), charging and discharging are switched during the damping oscillation by LCR, so the voltage at the end of charging and the integral amount during discharging change depending on the timing. In other words, the voltage difference ΔV at the end of charging in FIG. 19(b) is different from the voltage difference ΔV at the end of charging in FIG. 18(b), and the sum of the areas IS during discharging in FIG. 19(b) is different from the sum of the areas IS during discharging in FIG. 18(b). Therefore, just changing the charging and discharging frequency causes a difference in the capacitance detection results. As a result, there is a risk of false detection of the seated state.

[0157] Since it is the damping oscillation that is affected, a method of waiting until the damping oscillation converges before carrying out the charge / discharge operation may be considered. 20(a) and 20(b) are graphs that diagrammatically show another example of the operation of the detection circuit. 20(a) and 20(b) show the case where the charge / discharge time is extended in comparison with FIG. 18(a) and FIG. 18(b).

[0158] As shown in Fig. 20(a), at time T57, the capacitance detection means switches from the second state to the first state. The first state continues from time T57 to time T58. At time T58, the capacitance detection means switches from the first state to the second state. The second state continues from time T58 to time T59.

[0159] The charging time in Fig. 20(a) (from time T57 to time T58) is longer than the charging time in Fig. 18(a). Therefore, the voltage difference ΔV at the end of charging in Fig. 20(b) is smaller than the voltage difference ΔV at the end of charging in Fig. 18(b). For example, the voltage difference ΔV at the end of charging in Fig. 20(b) is sufficiently attenuated, and can be considered to be substantially zero. Also, the discharge time in FIG. 20(a) (from time T58 to time T59) is longer than the discharge time in FIG. 18(a). Therefore, the oscillation is sufficiently damped at the timing when the discharge time ends (time T59), and the sum of the areas IS during discharge in FIG. 20(b) is not easily affected by the discharge time and is stable. On the other hand, the sum of the areas IS during discharge in FIG. 18(b) is easily affected by the integration time and is not stable. Therefore, for example, the sum of the areas IS during discharge in FIG. 20(b) can be considered to be a substantially fixed value, and the error can be considered to be zero.

[0160] In this way, the error caused by the damping vibration can be suppressed by extending the charge / discharge time to converge the damping vibration. However, in this example, in order to change the charge / discharge frequency, the charge / discharge time must be further extended. In this case, the detection time becomes longer, and there is a risk that the seating determination will be delayed.

[0161] In contrast, in the embodiment, as described above with reference to Fig. 16(a) and Fig. 17(a), when changing the charge / discharge frequency, one of the charge time and the discharge time is made variable and the other is fixed. In other words, when changing the frequency of the switching operation, one of the time of the first state and the second state is made variable and the other time of the first state and the second state is made fixed. As a result, the operation that is affected by the change in the damping oscillation is only one of the charging and discharging, so that the influence of the damping oscillation can be reduced. Therefore, the occurrence of erroneous detection of the human body can be further suppressed.

[0162] In the embodiment, as shown in Fig. 16(a) and Fig. 17(a), the variable side of the first state and the second state is longer than the fixed side of the first state and the second state. For example, in Fig. 16(a) and Fig. 17(a), the time of the variable side is longer than the time for the oscillation of the potential of the detection electrode 12 to attenuate when the first state and the second state are switched. On the other hand, the time of the fixed side is shorter than the time for the oscillation of the potential of the detection electrode 12 to attenuate when the first state and the second state are switched. Note that the time for the oscillation of the potential of the detection electrode to attenuate is, for example, two or more periods, preferably three or more periods, of the attenuated oscillation when the capacitance detection means 17b is switched from the fixed side to the variable side.

[0163] By making the time on the variable side longer than the vibration attenuation time, it is possible to reduce the influence of the vibration of the potential of the detection electrode 12 on the variable side on the capacitance detection result. Therefore, it is possible to reduce the change in the influence of the vibration of the potential of the detection electrode 12 caused by changing the charge / discharge frequency. For example, in Figures 16(b) and 17(b), the charging time is long, and the vibration is almost converged at the end of charging (for example, time T32 and time T42), and the charging voltage is stable. The voltage difference ΔV is sufficiently small at the end of charging. In this way, if the vibration component at the end of charging has attenuated, the error is small even if the charging time is changed.

[0164] On the other hand, since the time on the fixed side is relatively short, the vibration of the potential of the detection electrode 12 on the fixed side is not attenuated, and affects the detection result of the capacitance. However, since the time on the fixed side is fixed, the influence of the vibration of the potential of the detection electrode 12 does not change with the change of the frequency and is a constant value. For example, in FIG. 16(b) and FIG. 17(b), the discharge time is short and fixed, so the integral value is stable. The integral value (area IS) of the vibration component during the discharge period becomes an error in the detection result of the capacitance, but since the discharge time is fixed, the change of the integral value (area IS) is suppressed. Therefore, even if there is an error in the detection result of the capacitance, the error component is kept constant regardless of the charge / discharge frequency, so that the influence on the judgment result of the seating can be suppressed.

[0165] In addition, by shortening the time for which the sensor is fixed, the time for one cycle is prevented from becoming longer, and the overall detection time is prevented from becoming longer. Even if the charging time is increased, the overall charging and discharging time can be made relatively short, so the response of the seat sensor is prevented from becoming slow.

[0166] As already described, in the examples of Figures 16(a) and 17(a), the fixed side is the first state, and the variable side is the second state. In other words, the time on the variable side is the charging time, and the time on the fixed side is the discharging time.

[0167] In the charging operation (first state), the voltage at the end of charging (final voltage applied to the capacitance) is proportional to the charge stored in the capacitance, so the voltage at the end of charging affects the capacitance detection result. Therefore, for example, even if noise is received during charging, there is no substantial effect on the capacitance detection result. Therefore, even if the charging time is extended and the possibility of noise entering the detection electrode during charging increases, noise resistance does not decrease. On the other hand, the discharge operation (second state) is an operation of discharging and integrating the charge stored in the detection electrode 12, so if noise is introduced during the discharge operation, the noise is also input to the integrating means and integrated, so that the noise remains as an error in the integrated voltage, and the detection result of the capacitance changes. Therefore, if the discharge time is longer, the noise resistance decreases accordingly. For the above reasons, when the charging and discharging times are the same (the reaction time of seating detection is the same), noise resistance is improved by selecting a longer charging time and a shorter discharging time. In Figures 16(a) and 17(a), the discharging time is shorter than the charging time, so noise is less likely to occur during the discharging time.

[0168] 21(a) and 21(b) are graphs illustrating the timing at which the discharge time ends. Figures 21(a) and 21(b) show waveforms during charging and discharging, similar to Figures 18(a) and 18(b). As shown in Figure 21(a), the capacitance detection means is in the first state from time T61 to T62. The capacitance detection means switches from the first state to the second state at time T62. The waveform shown in Figure 21(b) is a waveform when the user is not seated on the toilet seat. In order to explain the waveform of the damped vibration, a waveform in which the second state continues is shown for convenience, rather than a waveform in which the second state switches back to the first state after time T62.

[0169] The time of the second state is preferably ¼ of the period Pd of the damping oscillation of the potential of the detection electrode when switching between the first state and the second state while not seated. That is, as shown in Fig. 21(a), it is preferable that the capacitance detection means switches from the second state to the first state at time T63, which is ¼ of the period after time T62.

[0170] The resonant frequency of an LCR is determined by L and C, and therefore changes with fluctuations in L and C. Both L and C vary from one device to another and change with temperature, and there is also variation in the operating frequency of the control unit (e.g., a microcomputer) that generates the charge and discharge time, so even if the discharge time is controlled to a fixed value, the integration result will include variation, and it is impossible to completely avoid the effects of vibration, so conditions that are more stable against the effects of vibration are preferable.

[0171] The timing of 1 / 4 of the vibration period Pd is a flat portion where the voltage waveform of the detection electrode 12 changes from descending to ascending, and the effect of any change in the resonant frequency can be kept small compared to the portion where the slope of the vibration waveform is steep. The timings of 1 / 2 and 1 period have a steep vibration slope and are therefore easily affected by changes in vibration conditions, making the capacitance detection results unstable, and are therefore less suitable than the timing of 1 / 4 period. At the timing of 1 / 4 of the vibration period Pd, the vibration waveform is flat and is less affected by changes in vibration conditions.

[0172] Although there is a flat portion in the 3 / 4 cycle portion, this is the portion where the vibration waveform changes from rising to falling, and the LC resonant circuit has energy that lowers the voltage of the detection electrode 12. If discharging is switched from discharging to charging at this point, the voltage of the detection electrode 12 changes to the rising side, and the polarities of the two are opposite. Therefore, at the timing of the 3 / 4 cycle, the transition to charging may not be as smooth as at the timing of the 1 / 4 cycle. At the timing of the 1 / 4 cycle, the transition to charging is the opposite of the above, and both the LC resonance and the charging operation are operations that increase the potential of the detection electrode 12, so a smooth transition to charging can be achieved.

[0173] However, in the embodiment, the time of the second state (timing of the end of discharge) is not necessarily limited to ¼ of the period Pd, and may be any timing. Also, the time of the second state being ¼ of the period Pd does not necessarily mean ¼ exactly, but may include, for example, the range of variation of elements constituting the circuit.

[0174] The above describes the embodiments of the present invention. However, the present invention is not limited to these descriptions. Any design modifications made by a person skilled in the art to the above-described embodiments are also included within the scope of the present invention as long as they include the features of the present invention. For example, the shape, dimensions, materials, arrangement, installation form, etc. of each element of the toilet seat device are not limited to those exemplified, and can be modified as appropriate. Furthermore, the elements of each of the above-described embodiments can be combined to the extent technically possible, and such combinations are also included within the scope of the present invention as long as they include the features of the present invention. [Explanation of symbols]

[0175] 10 human body detection sensor, 11 overvoltage detection means, 12 detection electrode, 14, 14b detection circuit, 15 input terminal, 16 control section, 17, 17b electrostatic capacitance detection means, 18 power supply circuit, 19 off-delay means, 20 switch section, 22 charge amount measurement section, 30 power supply terminal, 31 rectifier circuit, 32 smoothing capacitor, 33 conversion circuit, 34 transformer, 37 capacitor, 38 coil, 42 protective resistor, 44 varistor, 50 integrating circuit, 52 integrating means, 54 transistor, 55, 56 resistor, 60, 61 varistor, 71 first switch, 72 second switch, 73 inverter circuit, 74 OR circuit, 80 diode, 81, 82 Zener diode, 83, 84 transistor, 85-88 resistors, 89 diodes, 91 resistors, 93 capacitors, 95 inverter circuits, 100 toilet device, 104 toilet bowl, 104a bowl portion, 106 operation portion, 110, 111 toilet seat device, 112 main body portion, 114 toilet seat, 114a opening, 116 toilet lid, 120 nozzle, 120a bidet flushing outlet, 120b rear flushing outlet, 130 upper plate, 130a seating surface, 130b inner surface, 132 lower plate, 202 control portion, 204 heater, 220 switching element, 240, 242 first and second adhesives, 250 thermal diffusion sheet, 910 human body detection sensor, ΔV voltage difference, C1, C2 Capacitance, DL Path, HB Human body, IS Area, P1, P2 Period, P11, P12, P21, P22 Duration, Pd Period, PS AC power supply, S1~S6, S100 Signal, SP Internal space, T31~T33, T41~T43, T51~T59, T61~T63 Time, VCC Power supply voltage

Claims

1. The toilet seat, A detection electrode whose capacitance changes in response to a person sitting on the toilet seat; a capacitance detection means having an input terminal electrically connected to the detection electrode and detecting the capacitance of the detection electrode; a control unit that determines whether or not the human body is seated based on a detection result of the capacitance detection means; an overvoltage detection means for detecting an overvoltage at the input terminal; Equipped with When the overvoltage detection means detects the overvoltage, the capacitance detection means temporarily stops detecting the capacitance and then resumes detecting the capacitance; The capacitance detection means is an integrating means for storing the charge discharged from the detection electrode; a first switch connected to a predetermined voltage; a second switch connected to the input terminal and the integrating means; a switching operation that alternately repeats a first state in which the first switch is on and the second switch is off to charge the detection electrode to the predetermined voltage, and a second state in which the first switch is off and the second switch is on to discharge the detection electrode; the integrating means stores the charge discharged from the detection electrode in the second state that is repeated by the switching operation; The control unit determines whether or not the human body is seated based on the charge accumulated in the integrating means, A toilet seat device characterized in that, when the overvoltage detection means detects the overvoltage, the capacitance detection means temporarily suspends the switching operation, sets the first switch and the second switch to the first state, and then resumes the switching operation.

2. 2. The toilet seat apparatus according to claim 1, further comprising an off-delay means for causing the first state to continue for a predetermined period of time when the overvoltage detection means detects the overvoltage.

3. 3. The toilet seat apparatus according to claim 1, wherein the detection electrode is provided on a rear surface of the toilet seat, has an area larger than that of a heater that warms the toilet seat, and diffuses heat from the heater to the toilet seat.

4. The toilet seat device according to claim 1 or 2, characterized in that the capacitance detection means is capable of changing the frequency of the switching operation that repeats the first state and the second state to a plurality of mutually different frequencies, and when changing the frequency of the switching operation, the time of one of the first state and the second state is made variable, and the time of the other of the first state and the second state is made fixed.

5. the one being the first state, The toilet seat apparatus according to claim 4, wherein the other of the two is in the second state.

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