Capacitance sensor

Abstract

The present application aims to provide an electrostatic capacitance sensor which can enlarge a detection range without enlarging a sensor electrode, and does not need to adjust each type of device according to a device lineup in which the electrostatic capacitance sensor is mounted. An electrostatic capacitance sensor (1) includes a sensor electrode (2), a detection means (4) for detecting a touch operation of a user on a detection area (8) on the basis of a change in capacitance of the sensor electrode (2), and a conductor (3) provided in the detection area (8) in which the touch operation is detected. The conductor (3) is arranged on the opposite side of the sensor electrode (2) with a gap or with a dielectric interposed therebetween, the area of the conductor (3) is larger than the area of the sensor electrode (2) as viewed in the direction of the sensor electrode (2) and the conductor (3) facing each other, and a portion of the conductor (3) faces the sensor electrode (2).

Description

Technical Field

[0001] The present disclosure relates to an electrostatic capacitance sensor that detects contact or approach of a detectable object relative to a detection area based on a change in capacitance of a sensor electrode. Background Art

[0002] For example, information and communication devices, household appliances, in-vehicle products, and other types of electronic devices are configured to perform various functions in response to a user's touch operation, and an electrostatic capacitance sensor is used to detect the user's touch operation. The electrostatic capacitance sensor has a sensor electrode disposed near a detection area where the user performs a touch operation in each type of device. When a part of the user's body (e.g., a finger) disturbs an electric field generated by the sensor electrode, the capacitance of the sensor electrode changes from C0 to C0 + ΔC. By detecting a change in the capacitance ΔC by a detection device connected to the sensor electrode, it can be determined whether there is a user's touch operation in the detection area (e.g., see PTL 1). In the present disclosure, a touch operation refers to an operation in which a part of the user's body or an input tool such as a touch pen (hereinafter referred to as a "detectable object") contacts or approaches the detection area.

[0003] The magnitude of the capacitance C0 of the sensor electrode is proportional to the area of the sensor electrode and inversely proportional to the distance between the sensor electrode and the detectable object. Therefore, the larger the area of the sensor electrode, the larger the capacitance C0. Therefore, even if the detection distance increases, a touch operation can be detected with high sensitivity. In addition, the larger the area of the sensor electrode, the wider the detection range that can be sensitive to the user's touch operation may be. In addition, the larger the area of the sensor electrode, the more effective the detection of an approach action is. Citation List Patent Literature

[0004] PTL 1: JP2015-210811A Summary of the Invention Technical Problem

[0005] As described above, since the detection range and sensitivity of the electrostatic capacitance sensor depend on the area of the sensor electrode, if the area of the sensor electrode is changed according to the lineup of devices equipped with the electrostatic capacitance sensor, the capacitance of the sensor electrode also changes. Therefore, it becomes complicated to adjust the capacitance of the sensor electrode for each type of device, as well as the parasitic capacitance depending on the sensor electrode, individual differences, sensitivity, threshold, etc. If the area of the sensor electrode is increased, the cost also increases accordingly.

[0006] The present disclosure focuses on solving the above problems, and its object is to provide a capacitive sensor that can expand the detection range without expanding the sensor electrodes and does not require adjustment for each device according to the lineup of devices equipped with the capacitive sensor. Solution to the technical problem

[0007] To achieve the above object, the main body of the capacitive sensor of the present disclosure is the capacitive sensor according to Item 1 below.

[0008] Item 1. A capacitive sensor, comprising a sensor electrode and a detection device for detecting the contact or approach action of a detectable object relative to a detection area based on a change in the capacitance of the sensor electrode. The capacitive sensor includes a conductor provided in the detection area. The conductor is arranged on the side opposite to the sensor electrode, with a gap therebetween or a dielectric inserted therebetween, and When viewed from the direction of the sensor electrode and the conductor facing each other, the area of the conductor is larger than the area of the sensor electrode and a part of the conductor facing the sensor electrode.

[0009] According to Item 1 above, preferably in the capacitive sensor, the detection device includes a detection component and a control component. The detection component is used to detect a change in the combined capacitance of the capacitance of the conductor and the capacitance of the sensor electrode as a change in the capacitance of the sensor electrode. The detection component includes a CV amplifier for converting the capacitance change into a voltage change, and the control component is configured to detect the contact or approach action of the detectable object relative to the detection area based on a detection signal corresponding to a change in the voltage output from the detection component.

[0010] The capacitive sensor of the present disclosure further includes the capacitive sensor according to Item 2 below as a more preferred aspect of the capacitive sensor in Item 1 above.

[0011] Item 2. The capacitive sensor according to Item 1, wherein the conductor covers the entire detection area.

[0012] The capacitive sensor of the present disclosure further includes the capacitive sensor according to Item 3 below as a more preferred aspect of the capacitive sensors in Items 1 and 2 above.

[0013] Item 3. The capacitive sensor according to Item 1 or Item 2, wherein the conductor is composed of any one of conductive ink, conductive resin, metal thin film, metal sheet, metal plate, metal mesh, conductive fabric, conductive knitted fabric, and conductive non-woven fabric.

[0014] The capacitance sensor of the present disclosure further includes the capacitance sensor according to Item 4 below, which is a more preferred aspect of the capacitance sensors in Items 1 to 3 above.

[0015] Item 4. The capacitance sensor according to any one of Items 1 to 3, wherein the detection area is a toilet seat, the conductor is provided on the back side of the toilet seat, and the sensor electrode is fixed to a part of the conductor via a dielectric. Advantageous technical effects of the invention

[0016] The capacitance sensor of the present disclosure detects the contact or approach action (such as a touch operation by a user) of a detectable object relative to the detection area through electrostatic induction between a sensor electrode having a smaller area and a conductor having an area larger than that of the sensor electrode. Therefore, in the capacitance sensor of the present disclosure, the conductor functions as the sensor electrode in the prior art and is configured to be sensitive to the approach of the detectable object to the conductor. Therefore, even if the area of the sensor electrode is small, the capacitance sensor of the present disclosure can expand the detection range sensitive to the contact or approach action of the detectable object by using a conductor with a larger area.

[0017] In addition, the capacitance sensor of the present disclosure does not need to increase the area of the sensor electrode in order to expand the detection range that may be sensitive to the contact or approach action of the detectable object, and the sensor electrode with a small area is sufficient to use, thus maintaining a low cost.

[0018] In the capacitance sensor of the present disclosure, the detection distance between the detectable object and the sensor electrode is the sum of the distance between the conductor and the sensor electrode and the distance between the conductor and the detectable object, which is larger than the detection distance of the sensor electrode with the same area in the prior art. Therefore, the capacitance sensor of the present disclosure can ensure a larger detection distance between the detectable object and the sensor electrode, and can sensitively detect the contact or approach action of the detectable object relative to the detection area even when the detection distance increases.

[0019] The detection range and sensitivity of the capacitance sensor of the present disclosure are independent of the area of the sensor electrode. Therefore, there is no need to change the area of the sensor electrode according to the lineup (detection range and sensitivity) of the devices on which the capacitance sensor is installed. In addition, even if the area of the conductor is changed according to the lineup (detection range and sensitivity) of the device, the capacitance change of the sensor electrode caused by the contact or approach action of the detectable object relative to the detection area is very small. Therefore, the capacitance sensor of the present disclosure can eliminate the need to adjust the capacitance of the sensor electrode for each type of device and to adjust the parasitic capacitance according to the sensor electrode, individual differences, sensitivity, threshold, etc. Description of the drawings

[0020] Figure 1 is a schematic diagram illustrating the functional configuration of a capacitive sensor according to an embodiment of the present disclosure. Figure 2 is a schematic diagram illustrating the functional configuration of a capacitive sensor according to an embodiment of the present disclosure. Figure 3 is a schematic diagram explaining the operating principle of a capacitive sensor according to an embodiment of the present disclosure. Figure 4 is a schematic diagram explaining the operating principle of a conventional capacitive sensor. Figure 5 is a schematic diagram illustrating an embodiment in which a capacitive sensor is applied to a toilet seat heater. Figure 6 (A) is a schematic diagram illustrating the back of a toilet seat, Figure 6 (B) is a schematic diagram illustrating a cross-section of the toilet seat. Figure 7 is a schematic diagram of an embodiment in which a capacitive sensor is applied to an attendance management system. Figure 8 is a schematic diagram illustrating a cross-section of a seat of an office chair. Figure 9 is a schematic diagram of an embodiment in which a capacitive sensor is applied to an automatic faucet device. Figure 10 (A) is a schematic diagram illustrating a part of the front of a faucet, Figure 10 (B) and (C) are schematic diagrams illustrating cross-sections of the faucet. Figure 11 is a schematic diagram of an embodiment in which a capacitive sensor is applied to a lamp, Figure 11 (B) is a schematic diagram illustrating a partial cross-section of the lamp. Figure 12 (A) is a schematic diagram of an embodiment in which a capacitive sensor is applied to wireless headphones, Figure 12 (B) is a schematic diagram illustrating a partial cross-section of the wireless headphones. Figure 13 (A) is a schematic diagram of an embodiment in which a capacitive sensor is applied to a touch switch, Figure 13 (B) is a schematic diagram illustrating the functional configuration of the touch sensor. Figure 14 (A) is a schematic diagram of an embodiment in which a capacitive sensor is applied to a touch switch, Figure 14 (B) is a schematic diagram illustrating the functional configuration of the touch sensor. Figure 15 (A) is a schematic diagram of an embodiment in which a capacitive sensor is applied to a water level sensor,Figure 15 (B) is a schematic diagram showing a partial cross-section of the water level sensor. Figure 16 shows Figure 15 a graph of the relationship between the water level and capacitance in the water level sensor. Figure 17 (A) is a circuit diagram when no contact or approach action of a detectable object is detected in the known invention, Figure 17 (B) shows the simulation result of measuring the current value flowing through the circuit (reference current value). Figure 18 (A) is a circuit diagram when a contact or approach action of a detectable object is detected in the known invention, Figure 18 (B) shows the simulation result of measuring the current value flowing through the circuit. Figure 19 (A) is a circuit diagram considering the LCR components when no contact or approach action of a detectable object is detected in the known invention, Figure 19 (B) shows the simulation result of measuring the current value flowing through the circuit (reference current value). Figure 20 (A) is a circuit diagram considering the LCR components when a contact or approach action of a detectable object is detected in the known invention, Figure 20 (B) shows the simulation result of measuring the current value flowing through the circuit. Figure 21 (A) is a circuit diagram when no contact or approach action of a detectable object is detected in the electrostatic capacitance sensor of the present disclosure, Figure 21 (B) shows the simulation result of measuring the voltage value of the circuit (reference voltage value). Figure 22 (A) is a circuit diagram when a contact or approach action of a detectable object is detected in the electrostatic capacitance sensor of the present disclosure, Figure 22 (B) shows the simulation result of measuring the voltage value of the circuit. Figure 23 (A) is a circuit diagram considering the LCR components when no contact or approach action of a detectable object is detected in the electrostatic capacitance sensor of the present disclosure, Figure 23 (B) shows the simulation result of measuring the voltage value of the circuit (reference voltage value). Figure 24 (A) is a circuit diagram considering the LCR components and having calibration for compensating parasitic capacitance when no contact or approach action of a detectable object is detected in the electrostatic capacitance sensor of the present disclosure, Figure 24 (B) shows the simulation result of measuring the voltage value of the circuit (reference voltage value). Figure 25(A) is a circuit diagram of a capacitance sensor according to the present disclosure that takes into account the LCR component when detecting the contact or approach of a detectable object and has calibration for compensating parasitic capacitance. Figure 25 (B) shows the simulation results of the voltage values of the measurement circuit. Detailed implementation

[0021] Overview and description of the overall configuration of the capacitive sensor The capacitance sensor according to the present disclosure is used to detect a user's touch operation so that, for example, an electronic device (such as an information and communication device, a household appliance, and an in-vehicle product) can perform various functions in response to the user's touch operation. The capacitance sensor detects a change in the capacitance of the sensor electrode caused by the approach or contact of a detectable object (conductor) with the detection area of each device. The detectable object is, for example, a part of the user's body or a special input tool such as a touch pen, thereby determining whether there is a touch operation on the detection area. An embodiment of the capacitance sensor according to the present disclosure will be described below with reference to the drawings. The capacitance sensor according to the present disclosure is not limited to the following embodiments.

[0022] Figure 1 and Figure 2 shows the functional configuration of the capacitance sensor 1. The capacitance sensor 1 includes a sensor electrode 2, a conductor 3 provided in a detection area 8 for receiving a user's touch operation on the device, and a detection device 4 for determining whether there is a touch operation in the detection area 8 based on the change in the capacitance of the sensor electrode 2.

[0023] Explanation of the sensor electrode The sensor electrode 2 is generally known and can be formed of materials commonly used for sensor electrodes of capacitance sensors. Examples of such materials include carbon, such as graphite and carbon black; metals, such as aluminum, copper, silver, and gold; conductive resins, such as thiophene-based conductive polymers and polystyrene sulfonate (PSS); and composites thereof.

[0024] The sensor electrode 2 has a planar body shape, such as a flat plate or sheet, and its outer shape is, for example, rectangular or circular. The size of the sensor electrode 2 is not particularly limited, but the length is 3 mm or more and 80 mm or less, and the width is 3 mm or more and 80 mm or less (if it is circular, the diameter is 3 mm or more and 80 mm or less), and preferably the length is 3 mm or more and 20 mm or less, and the width is 3 mm or more and 20 mm or less (if it is circular, the diameter is 3 mm or more and 20 mm or less). The sensor electrode 2 is formed so that the area of the main surface (the area viewed from the direction in which the sensor electrode 2 and the conductor 3 face each other, as described below) is small.

[0025] A positive voltage relative to ground is applied to the sensor electrode 2 through a power supply (not shown). As a result, positive charges are uniformly generated on the sensor electrode 2.

[0026] Explanation of the conductor The conductor 3 can be made of carbon (such as graphite or carbon black), metal (such as aluminum, copper, silver, or gold), conductive resin (such as thiophene-based conductive polymer or polystyrene sulfonate (PSS)), conductive ink, conductive fiber (such as chemical fiber containing metal or carbon, chemical fiber with a metal surface coating, or metal fiber made of metal), or a composite material thereof.

[0027] The conductor 3 has a planar body shape, such as a flat plate, sheet, or film. There is no particular limitation on the conductor 3, but preferably it can be a metal film (including electroplating and vapor deposition), metal sheet (including metal foil), metal plate, metal mesh or fabric (including net), knitted fabric, or non-woven fabric formed by conductive fiber.

[0028] The conductor 3 is disposed in the detection area 8 in the device. The conductor 3 can be disposed on the side of the detection area 8 for the user to touch, or on the other side opposite to the side where the user touches.

[0029] The conductor 3 is placed opposite to the sensor electrode 2, that is, the main surfaces of the two face each other. The conductor 3 is placed separately from the sensor electrode 2, with air sandwiched between the two, or a dielectric (such as an insulator) is sandwiched between the conductor 3 and the sensor electrode 2.

[0030] The external shape of the conductor 3 is, for example, rectangular or circular. When viewed from the direction in which the sensor electrode 2 and the conductor 3 face each other, the conductor 3 is shaped to have an area larger than that of the sensor electrode 2, and a part of the sensor electrode 2 faces the conductor 3.

[0031] The size of the conductor 3 is not particularly limited, but is preferably large enough to cover the entire (or almost the entire) detection area 8. This allows the entire detection area 8 to be sensitive to the user's touch operation.

[0032] The conductor 3 is arranged such that a part of it is within the electric field generated by the sensor electrode 2. When a part of the conductor 3 is present in the electric field, electrostatic induction occurs in the conductor 3, resulting in polarization. Then, due to the attraction of the positive charges on the sensor electrode 2, different types of negative charges are generated in the part of the conductor 3 close to the sensor electrode 2, and an equal amount of positive charges are generated in the part away from the sensor electrode 2.

[0033] The smaller the distance h0 between the conductor 3 and the sensor electrode 2, the easier it is for electrostatic induction to occur, and the greater the amount of negative charge generated in the conductor 3; therefore, the amount of positive charge generated in the conductor 3 is also greater. Accordingly, since the electric field generated between the part of the conductor 3 where positive charge is generated and the ground increases, the distance h0 between the conductor 3 and the sensor electrode 2 is preferably short.

[0034] Regarding the positional relationship between the conductor 3 and the sensor electrode 2, the conductor 3 is located on the side where the user will touch with respect to the sensor electrode 2; however, the sensor electrode 2 may also be located on the side where the user will touch with respect to the conductor 3.

[0035] Explanation of the capacitance change caused by the user's touch operation As Figure 1 and Figure 3 shown in (A), in the case where there is no user touch operation in the detection area 8, when the capacitance of the conductor 3 is taken as C0, the capacitance of the sensor electrode 2 is taken as C1 (C1 < C0), and C0 and C1 in the present disclosure are connected in series; therefore, the combined capacitance of the sensor electrode 2 is C0 × C1 / (C0 + C1). The capacitance C0 × C1 / (C0 + C1) is monitored by the detection device 4. The combined capacitance C0 × C1 / (C0 + C1) of the sensor electrode 2 is the combined capacitance of the capacitance C0 of the conductor 3 and the capacitance C1 of the sensor electrode 2.

[0036] Conversely, as Figure 2 and Figure 3 shown in (B), when the user brings a detectable object 9 such as a part of the user's body (such as a finger) close to or into contact with the detection area 8 to perform a touch operation, (when the distance h1 between the conductor 3 and the detectable object 9 decreases), the detectable object 9 interferes with the electric field from the conductor 3. Since the user's body is grounded, charges accumulate through the user's body as a conductor, and the capacitance of the conductor 3 changes from C0 to C0 + ΔC. When the capacitance (charge) of the conductor 3 becomes C0 + ΔC, the combined capacitance of the sensor electrode 2, that is, the combined capacitance of the capacitance C0 + ΔC of the conductor 3 and the capacitance C1 of the sensor electrode 2 is (C0 + ΔC) × C1 / {(C0 + ΔC) + C1}. Therefore, at the position where the user touches the detection area 8, the change ΔC' in the capacitance of the sensor electrode 2 of the present disclosure, that is, the change in the combined capacitance of the capacitance of the conductor 3 and the capacitance of the sensor electrode 2, is as shown in Equation 1 below, and the change ΔC' in the capacitance of the sensor electrode 2 is detected by the detection device 4.

[0037] [Equation 1] ΔC' = (C0 + ΔC) × C1 / {(C0 + ΔC) + C1} - C0 × C1 / (C0 + C1) = ΔC × C1 2 / {(C0 + C1) × (C0 + ΔC + C1)}

[0038] Since the change in the capacitance ΔC’ of the sensor electrode 2 of the present disclosure is the denominator of Equation 1, (C0 + C1)×(C0 + ΔC + C1) = C0 2 + 2C0C1 + C0ΔC + C1ΔC + C1 2 > C1 2 , C1 in Equation 1 2 / {(C0 + C1)×(C0 + ΔC + C1)} is less than 1. Therefore, ΔC’ is less than ΔC.

[0039] In the electrostatic capacitance sensor of the prior art, when a touch operation of a user is detected by a sensor electrode having the same area as the conductor 3 of the electrostatic capacitance sensor 1 of the present disclosure, the capacitance change of the sensor electrode caused by the touch operation of the user is (C0 + ΔC) - C0 = ΔC, as Figure 4 (A) and (B) show. Therefore, it can be seen that in the electrostatic capacitance sensor 1 of the present disclosure, the change amount of the capacitance of the sensor electrode 2 caused by the touch operation of the user is smaller than the capacitance change amount of the sensor electrode 2 of the prior art.

[0040] Explanation of the detection device When the user brings the detectable object 9 close to or into contact with the conductor 3 in the detection area 8, the capacitance of the sensor electrode 2 changes according to the distance h1 between the conductor 3 and the detectable object 9. The detection device 4 includes a detection component 5 for detecting the capacitance change of the sensor electrode 2.

[0041] The detection component 5 is electrically connected to the sensor electrode 2. The detection part 5 has an electrical / electronic circuit for detecting the capacitance change of the sensor electrode 2. In order to detect the capacitance change of the sensor electrode 2, the detection component 5 may be composed of, for example, a CV amplifier for converting the capacitance change into a voltage change and a detection circuit having a CV amplifier gain adjustment function for adjusting the sensitivity. When there is no touch operation of the user in the detection area 8, there is no detectable object 9 in the electric field of the conductor 3, so the capacitance does not change or the voltage of the CV amplifier does not change. On the other hand, when the detectable object 9 interferes with the electric field of the conductor 3 due to the user's touch operation on the detection area 8, the capacitance of the sensor electrode 2 increases, and the voltage change corresponding to the capacitance increase from the CV amplifier is output from the detection circuit after being multiplied by the gain. The detection signal may be in the form of analog data or digital data.

[0042] The method of using the detection component 5 to detect the capacitance change of the sensor electrode 2 is not limited to the above embodiments, and various conventional known methods can also be used. For example, (1) a method for measuring the time difference required for discharging after charging the sensor electrode 2 with a fixed charge, and (2) a method for detecting the capacitance change of the sensor electrode 2 based on the change in the oscillation state of an oscillator circuit. The detection component 5 can be composed of electrical / electronic circuits, switches, etc., and these circuits and switches are suitable for use in the above methods (1) and (2) in a conventional capacitance sensor.

[0043] The detection device 4 includes a control component 6, and the control component 6 determines that a touch operation has occurred in the detection area 8 based on the detection signal output from the detection component 5. The control component 6 can be composed of, for example, a microcomputer. The control component 6 includes a receiver component 60, a processing component 61, an output component 62, etc.

[0044] The receiver component 60 is configured as an interface for receiving the detection signal. When the detection signal is in the form of analog data, the receiver component is configured to include an appropriate conversion circuit, and the conversion circuit includes an A / D converter. The processing component 61 is configured to determine whether a touch operation has occurred in the detection area 8 based on the detection signal. For example, when the processing component 61 determines that the change amount of the capacitance of the sensor electrode 2 exceeds a predetermined threshold stored in the memory, the processing component 61 determines that a touch operation has occurred in the detection area 8. The output component 62 is configured as an interface for outputting a control signal to allow the control device 10 installed in the device to execute the functions of each device. The processing component 61 is configured to output a control signal from the output component 62 when the processing component 61 determines that a touch operation has occurred in the detection area 8. The control signal can be in the form of analog data or digital data. When the control signal is in the form of analog data, the output component is configured to include an appropriate conversion circuit, and the conversion circuit includes a D / A converter.

[0045] The detection device 4 can be in the form of a module 7 containing the sensor electrode 2, or can be in a form separate from the sensor electrode 2.

[0046] Function and influence of the capacitive sensor According to the capacitance sensor 1 of the present embodiment described above, the touch operation of the user on the detection area 8 is detected by the electrostatic induction between the sensor electrode 2 with a smaller area and the conductor 3 with an area larger than that of the sensor electrode 2. Therefore, in the capacitance sensor 1 of the present embodiment, the conductor 3 acts as the sensor electrode in the prior art and is configured to be sensitive to the approach of the detectable object 9 to the conductor 3. Therefore, even if the area of the sensor electrode 2 is small, the capacitance sensor 1 of the present disclosure can expand the detection range sensitive to the touch operation of the user by using the conductor 3 with a larger area.

[0047] In addition, the capacitance sensor 1 of this embodiment does not need to increase the area of the sensor electrode 2 in order to expand the detection range sensitive to the user's touch operation, and the sensor electrode 2 with a small area is sufficient, thus maintaining a low cost.

[0048] In the capacitance sensor 1 of this embodiment, the detection distance h between the detectable object 9 and the sensor electrode 2 (as Figure 2 shown) is the sum of the distance h0 between the conductor 3 and the sensor electrode 2 and the distance h1 between the conductor 3 and the detectable object 9, and this detection distance h is greater than the detection distance h0 of the sensor electrode with the same area in the prior art. Therefore, the capacitance sensor 1 of this embodiment can ensure that the detection distance h between the detectable object 9 and the sensor electrode 2 is relatively large, and even if the detection distance h increases, the touch operation of the user on the detection area 8 can be detected with high sensitivity.

[0049] In the capacitance sensor 1 of this embodiment, the detection range and sensitivity do not depend on the area of the sensor electrode 2. Therefore, it is not necessary to change the area of the sensor electrode 2 according to the device lineup (detection range and sensitivity) where the capacitance sensor is installed. In addition, even if the area of the conductor 3 changes according to the device lineup (detection range and sensitivity), due to the user's touch operation on the detection area, the capacitance of the sensor electrode 2 will change slightly. Therefore, the capacitance sensor 1 of this embodiment can eliminate the need to adjust the capacitance of the sensor electrode 2 for each device, as well as the parasitic capacitance, individual differences, sensitivity, threshold, etc. depending on the sensor electrode 2.

[0050] In the capacitance sensor 1 of this embodiment, the combined capacitance C0×C1 / (C0 + C1) of the capacitance C0 of the detection conductor 3 and the capacitance C1 of the sensor electrode 2 is detected in order to detect the contact or approach action of the detectable object. Similar to the capacitive touch sensor disclosed in JP2021 - 99297A (hereinafter referred to as the "known invention"), when the total capacitance C0 + C1 of the capacitance C0 (Cs1 in JP2021 - 99297A) of the conductor (metal sheet 2 in JP2021 - 99297A) and the capacitance C1 (Cs2 in JP2021 - 99297A) of the sensor electrode (detection electrode 3 in JP2021 - 99297A) is detected, if the capacitance of the conductor increases to C0+ΔC due to the contact or approach action of the detectable object, the total capacitance detected when the detectable object makes a contact or approach action is C0+ΔC + C1. Therefore, in the known invention, the capacitance change before and after the contact or approach action of the detectable object is C0+ΔC + C1-(C0 + C1)=ΔC. This directly detects the change ΔC in the capacitance of the conductor increased due to the contact or approach action of the detectable object.

[0051] In contrast, in the electrostatic capacitance sensor 1 of the present embodiment, since the combined capacitance of the capacitance C0 of the conductor and the capacitance C1 of the sensor electrode are detected, when the capacitance of the conductor increases to C0+ΔC due to the contact or approach action of the detectable object, their combined capacitance detected when the detectable object makes a contact or approach action is (C0+ΔC)×C1 / {(C0+ΔC)+C1}. Therefore, in the electrostatic capacitance sensor 1 of the present embodiment, the capacitance change before and after the contact or approach action of the detectable object is ΔC×C1 2 / {(C0+C1)×(C0+ΔC+C1)}=ΔC', and as described above, this ΔC' is smaller than the capacitance change ΔC of the conductor increased by the contact or approach action of the detectable object. Therefore, the electrostatic capacitance sensor 1 in this embodiment can detect the change in capacitance caused by the contact or approach action of the detectable object in a smaller range, thereby achieving the following functions and effects.

[0052] (1) Since the change in capacitance caused by the contact or approach of the detectable object can be detected within a smaller range, a larger change in capacitance on the conductor side can be detected within a smaller dynamic range. (2) Electrostatic capacitance sensors with a smaller dynamic range are sufficient, thereby reducing costs. (3) The capacitance change caused by the temperature change on the conductor side becomes smaller, so it is less susceptible to external interference. (4) The same sensor electrode can be used to replace various directly connected conductors. (5) As described below, the capacitance of a capacitor or the like provided as a voltage detection means in the detection device can be reduced.

[0053] In the electrostatic capacitance sensor 1 of the present embodiment, the change in capacitance is converted into a change in voltage, and the contact or approach action of the detectable object is detected based on the change in voltage. In the known invention described above, the capacitor is charged and discharged by a switch operation, and the current value flowing through the circuit when the capacitor is discharged is detected by the current detection component. Unlike the known invention in which the change in capacitance is converted into a change in current and the contact or approach action of the detectable object is detected based on the change in current, the electrostatic capacitance sensor 1 of the present embodiment has the following functions and effects.

[0054] In the known invention, when no contact or approach action of the detectable object is detected, Figure 17 (B) shows the simulation result of measuring the current value (reference current value) flowing through the circuit, as shown in FIG. Figure 17 (A) As described above, the capacitance C0 of the conductor is 40pF, the capacitance C1 of the sensor electrode is 10pF, the power supply voltage is 5V, and the resistance value of the resistor used as the current detection component is 2kΩ. Figure 17(B), 1.95 mA is detected as the peak reference current value.

[0055] On the other hand, in the known invention, when the contact or approach action of the detectable object is detected, Figure 18 (B) shows the simulation result of measuring the current value flowing through the circuit, as Figure 18 (A) shows, the capacitance C0 of the conductor increases by 30 pF due to the contact or approach action of the detectable object. According to Figure 18 (B), 2.05 mA is detected as the peak current value.

[0056] Therefore, in the known invention, for example, the threshold current value can be set in the range greater than 1.96 mA and less than 2.05 mA, and the change amount of the current starting from the reference current value of 1.95 mA can be set to, for example, about 0.1 mA, so that it can be used to detect the contact or approach action of the detectable object in the simulation.

[0057] However, it is obvious to those skilled in the art that in the environment of actually operating the touch sensor, due to the influence of the substrate, wires, etc., invisible LCR components such as parasitic capacitance, parasitic inductance, and parasitic resistance will be generated between the detection electrode and the detection component. In the known invention, as Figure 19 (A) shows, in the actual operating environment, LCR components such as parasitic capacitance, parasitic inductance, and parasitic resistance will be generated between the detection electrode and the current detection component ( Figure 19 (the part surrounded by the double-dot chain line in (A)). Therefore, it is necessary to take these LCR components into account for the actual operation of the touch sensor.

[0058] Figure 19 (B) shows the simulation result of measuring the reference current value flowing through the circuit when the contact or approach action of the detectable object is not detected, where the parasitic capacitance is 10 pF, the parasitic inductance is 10 μh, and the parasitic resistance is 10 Ω. According to Figure 19 (B), 1.70 mA is detected as the peak reference value. In addition, Figure 20 (B) shows the simulation result of measuring the reference current value flowing through the circuit when the contact or approach action of the detectable object is detected, as Figure 20 (A) shows, the parasitic capacitance is 10 pF, the parasitic inductance is 10 μh, and the parasitic resistance is 10 Ω. According to Figure 20 (B), 2.1 mA is detected as the peak current value.

[0059] Therefore, in the known invention, when considering the actual operating environment, the reference current value detected when no detectable object is detected changes from 1.95 mA to 1.7 mA, and the current value when a detectable object is detected also changes from 2.05 mA to 2.1 mA. Regarding the current value when a detectable object is detected, the amount of current change compared to the reference current value also changes from 0.1 mA to 0.4 mA. Since the current values considering the above-mentioned actual operating environment vary according to the individual operating environment, if the contact or approach action of a detectable object is detected based on the current value, it is impossible to set an appropriate threshold value, etc. in the current detection component, and it is impossible to clearly indicate the detected current value or the amount of current change to determine whether the detectable object makes a contact or approach action.

[0060] In contrast, the capacitance sensor 1 in the present embodiment converts a capacitance change into a voltage change and detects the contact or approach action of a detectable object based on the voltage change. When no contact or approach of a detectable object is detected, Figure 21 (B) shows the simulation result of measuring the voltage value (reference voltage value), as Figure 21 (A) shows, the capacitance C0 of the conductor is 40 pF, the capacitance C1 of the sensor electrode is 10 pF, the voltage of the power supply is 5 V, and the resistance of the capacitor used as the voltage detection component is 8 pF (the same value as the combined capacitance of C0 and C1). According to Figure 21 (B), 2.5 V can be detected as the peak reference voltage value.

[0061] On the other hand, as Figure 22 (A) shows, when the contact or approach action of a detectable object is detected, Figure 22 (B) shows the simulation result of measuring the voltage value. The conductor capacitance C0 increased due to the contact or approach action of the detectable object is 30 pF. According to Figure 22 (B), 2.6 V is detected as the peak voltage value.

[0062] Even when converting the capacitance change into a voltage change, considering the LCR components in the actual operating environment, such as parasitic capacitance, parasitic inductance, and parasitic resistance, Figure 23 (B) shows the simulation result of measuring the reference voltage value when no contact or approach action of a detectable object is detected, as Figure 23 (A) shows, the parasitic capacitance is 10 pF, the parasitic inductance is 10 μh, and the parasitic resistance is 10 Ω. According to Figure 23 (B), 3.5 V is detected as the peak reference voltage value.

[0063] Even when converting the capacitance change into a voltage change, considering the actual operating environment, the reference voltage value detected when no detectable object is detected will change from 2.5V to 3.5V. This change is based on parasitic capacitance. Therefore, by allowing the circuit to be calibrated to cancel out the parasitic capacitance, the deviation in the voltage detection value in the actual operating environment can be eliminated. For example, as Figure 24 (A) shows, by providing a capacitor for calibrating the parasitic capacitance of 10pF (the part enclosed by the dashed line in Figure 24 (A)), the deviation in the voltage detection value in the actual operating environment can be eliminated. Figure 24 (B) shows the simulation results of measuring the reference voltage value when the calibration capacitor is provided. According to Figure 24 (B), 2.5V can be detected as the peak reference voltage value, and the deviation in the voltage detection value has been eliminated.

[0064] In addition, regarding the voltage value when a detectable object's contact or approach action is detected, Figure 25 (B) shows the measured simulation results when a capacitor (the part enclosed by the dashed line in Figure 25 (A)) is provided to calibrate the parasitic capacitance of 10pF, as shown in Figure 25 (A). According to Figure 25 (B), 2.6V is detected as the peak voltage value, which is the same as the peak voltage of 2.6V in Figure 22 (B). Even considering the actual operating environment, the voltage value when a detectable object is detected is the same.

[0065] As described above, like using the capacitance sensor 1 of this embodiment, by converting the capacitance change into a voltage change and detecting the contact or approach action of a detectable object based on the voltage change, even if the actual environment changes, an appropriate threshold value, etc. can be set in the detection device, and it can be appropriately determined whether the detectable object is performing a contact or approach action.

[0066] In the known invention, JP2021 - 99297A neither discloses nor proposes means and methods for eliminating the deviation in the current detection value caused by the influence of the actual operating environment, and the above - mentioned means and methods are not easily conceivable even with reference to the common general knowledge at the time of application.

[0067] Explanation of the usage cases of the capacitive sensor Next, examples of how to use the capacitance sensor of the present disclosure in various types of devices will be given. The application of the capacitance sensor of the present disclosure is not limited to the following examples.

[0068] (1) Toilet seat heater Figure 5 And Figure 6An example of using the capacitance sensor 1 in the toilet seat heater 11 is shown. In the toilet seat heater 11 of the illustrated example, the toilet seat 12 is a detection area 8 for detecting a user's touch operation, and it is configured to drive the heater in response to the capacitance sensor 1 detecting the action of the user sitting on the toilet seat 12 as a touch operation. In the illustrated example, the sensor electrode 2 and the detection device 4 of the capacitance sensor 1 are in the form of a module 7, where the sensor electrode 2 is integrated into the detection device 4.

[0069] The toilet seat 12 is made of synthetic resin. For example, an aluminum sheet (aluminum foil) is attached as the conductor 3 to the entire back surface of the toilet seat 12, and the module 7 is attached to a part of the conductor 3 via a dielectric (such as an adhesive or double-sided tape 13). The module 7 is located at the rear end of the detection area 8. In addition, a heating wire (wire heater) 14 is also laid on the back surface of the toilet seat 12. The heating wire 14 is connected to a control device for controlling the operation of the toilet seat heater 11, and the control device controls the power supply to the heating wire 14 using known electrical / electronic circuits, switches, etc.

[0070] When the user sits on the toilet seat 12, since the conductor 3 covers the entire area of the toilet seat 12, that is, the detection area 8, the capacitance of the conductor 3 increases, and the capacitance of the sensor electrode 2 also increases. The change in the capacitance of the sensor electrode 2 is detected by the detection device 4, and the capacitance sensor 1 accordingly detects the touch operation of the user on the detection area 8. This detection information is transmitted as a control signal to the control device of the toilet seat heater 11 by wire or wirelessly, and the control device of the toilet seat heater 11 heats the heating wire 14 accordingly to perform the heating function of the toilet seat. On the other hand, when the user stands up from the toilet seat 12, the capacitance of the conductor 3 decreases, and the capacitance of the sensor electrode 2 also decreases. The change in the capacitance of the sensor electrode 2 can be detected by the detection device 4, and the capacitance sensor 1 accordingly detects that the touch operation of the user on the detection area 8 is released. This detection information is transmitted as a control signal area to the control device of the toilet seat heater 11 by wire or wirelessly, so that the control device of the toilet seat heater 11 stops the heating of the heating wire 14 to stop the heating function of the toilet seat.

[0071] In this embodiment, the control component 6 of the detection device 4 replaces the control device of the toilet seat heater 11, and the control component 6 can be configured to heat the heating wire 14 to perform the heating function of the toilet seat when detecting the touch operation of the user on the detection area 8.

[0072] (2) Attendance management system Figure 7 and Figure 8An example of using the capacitive sensor 1 in the attendance management system 21 is shown. In the attendance management system 21 of the illustrated example, the seat 22 of the office chair is the detection area 8 for detecting the touch operation of the user, and it is configured to check the attendance in response to the capacitive sensor 1 detecting the action of the user sitting on the seat 22 of the office chair as a touch operation. In the illustrated example, the sensor electrode 2 and the detection device 4 of the capacitive sensor 1 are in the form of a module 7, where the sensor electrode 2 is integrated into the detection device 4.

[0073] The seat 22 is made of synthetic leather or fabric. For example, a conductive mesh fabric as the conductor 3 is attached to the entire bottom of the seat 22, and the module 7 is attached to a part of the conductor 3 via a dielectric (such as an adhesive or double-sided tape 23). The module 7 is provided at the side end of the detection area 8.

[0074] When the user sits on the seat 22, since the conductor 3 covers the entire seat 22 (i.e., the detection area 8), the capacitance of the conductor 3 increases, and the capacitance of the sensor electrode 2 also increases. The detection device 4 detects this change in the capacitance of the sensor electrode 2, and the capacitive sensor 1 thereby detects the touch operation of the user on the detection area 8. This detection information is transmitted as a control signal to the control device (not shown) of the attendance management system by wire or wirelessly, and the control device of the attendance management system 21 checks the attendance accordingly. On the other hand, when the user stands up from the seat 22, the capacitance of the conductor 3 decreases, and the capacitance of the sensor electrode 2 also decreases. The detection device 4 detects the change in the capacitance of the sensor electrode 2, and the capacitive sensor 1 thereby detects whether the touch operation of the user on the detection area 8 is released. This detection information is transmitted as a control signal to the control device of the attendance management system 21 by wire or wirelessly, and the control device of the attendance management system 21 checks the attendance accordingly.

[0075] (3) Automatic faucet device Figure 9 and Figure 10 An example of using the capacitive sensor 1 in the automatic faucet device 31 is shown. The automatic faucet device 31 of the illustrated example includes a water outlet member 37, a water guiding member 35, and a handle member 38, and a part of the water guiding member 35 is the detection area 8 for detecting the touch operation of the user. The automatic faucet device 31 is configured to discharge water from the water outlet member 37 in response to the capacitive sensor 1 detecting the action of the user bringing the hand close to the water guiding member 35 as a touch operation. In the illustrated example, the sensor electrode 2 and the detection device 4 of the capacitive sensor 1 are in the form of a module 7, where the sensor electrode 2 is integrated into the detection device 4.

[0076] The portion 32 of the water guiding member 35 other than the detection area 8 is made of an alloy (such as brass) or a synthetic resin (such as ABS resin), and its outer surface is coated with a metal plating 34 (such as chromium plating). A part 33 of the detection area 8 in the water guiding member 35 is made of a synthetic resin, and the outer surface of this part 33 is coated with, for example, a metal plating to serve as a conductor 3. There is a gap between the metal plating 34 on the outer surface of the portion 32 of the water guiding member 35 other than the detection area 8 and the conductor 3 on the outer surface of the part 33 of the detection area 8, and the metal plating 34 and the conductor 3 are electrically disconnected and preferably grounded. The module 7 is attached to the inner surface of the part 33 of the detection area 8 in the conductor 3 via a dielectric (such as an adhesive or a double-sided tape 36) so as to face a part of the conductor 3. The module 7 is provided at a corner at the lower end of the detection area 8. In addition, a solenoid valve is provided on the water supply pipe in the automatic faucet device 31. The solenoid valve is connected to a control device for controlling the operation of the automatic faucet device 31, and the control device controls the opening and closing of the solenoid valve.

[0077] When the user's hand approaches the detection area 8 (which is a part of the water guiding member 35), since the conductor 3 covers the entire detection area 8, the capacitance of the conductor 3 increases, and the capacitance of the sensor electrode 2 also increases. The detection device 4 detects the capacitance change of the sensor electrode 2, and the capacitive sensor 1 thereby detects the touch operation of the user on the detection area 8. This detection information is transmitted as a control signal to the control device of the automatic faucet device 31 by wire or wirelessly, and the control device of the automatic faucet device 31 opens the solenoid valve to release water accordingly. After the water has flowed out for a predetermined period of time, the control device of the automatic faucet device 31 closes the solenoid valve to stop the water flow.

[0078] In Figure 9 and Figure 10 , a part of the water guiding member 35 serves as the detection area 8. However, the entire water guiding member 35 can also serve as the detection area 8. In this case, the entire outer surface of the water guiding member 35 is covered with a metal plating as the conductor 3. There is a gap between the metal plating covering the outer surfaces of the water outlet member 37 and the handle member 38 and the conductor 3 on the outer surface of the water guiding member 35 so that the water outlet part 37 and the handle part 38 are electrically disconnected from the water guiding member 35. The metal plating 38 on the outer surfaces of the water outlet member 37 and the handle member 38 is preferably grounded.

[0079] In an example of using the capacitive sensor 1 in the automatic faucet device 31, the control component 6 of the detection device 4 replaces the control device of the automatic faucet device 31, and this control component 6 can be configured to open and close the solenoid valve when detecting the touch operation of the user on the detection area 8, thereby opening and closing the water supply.

[0080] (4) Lamp Figure 11 This is an example of using the capacitance sensor 1 in the lamp 41. In the lamp 41 of the illustrated example, the inclined portion 43, which is part of the base 42 - 43, is the detection area 8 for detecting the user's touch operation. The lamp 41 is configured to turn on and off the light source in response to the capacitance sensor 1 detecting the action of the user's hand approaching the inclined portion 43 as a touch operation. In the illustrated example, the sensor electrode 2 and the detection device 4 of the capacitance sensor 1 are in the form of a module 7, where the sensor electrode 2 is integrated into the detection device 4.

[0081] The base 42 - 43 is made of, for example, wood or synthetic resin, and the entire outer surface of the inclined portion 43 is coated with a conductor 3 such as a metal plating. The module 7 is attached to the inner surface of the inclined member 43 via a dielectric (such as an adhesive or double-sided tape 46) so that the module 7 faces a part of the conductor 3. The module 7 is provided at the upper end portion of the detection area 8. The entire outer surface of the lower portion 42 of the base 42 - 43 may also be coated with a metal plating 45. However, there is a gap between the metal plating 45 on the outer surface of the lower portion 42 and the conductor 3 on the outer surface of the inclined portion 43. The metal plating 45 is electrically disconnected from the conductor 3 and is preferably grounded. In addition, a light source is provided inside the glass cover 44 attached above the base 42 - 43, for example. The light source is connected to a control device for controlling the operation of the lamp 41, and the control device controls the power supply to the light source using a known electrical / electronic circuit, switch, etc.

[0082] When the user brings their hand close to the inclined portion 43 of the base 42 - 43, since the conductor 3 covers the entire area of the inclined portion 43 (i.e., the detection area), the capacitance of the conductor 3 increases, and the capacitance of the sensor electrode 2 also increases. The detection device 4 detects this change in the capacitance of the sensor electrode 2, and the capacitance sensor 1 thereby detects the user's touch operation on the detection area 8. This detection information is transmitted as a control signal to the control device of the lamp 41 by wire or wirelessly, and the control device of the lamp 41 energizes the light source accordingly to turn on the lamp 41. On the other hand, when the user releases their hand from the inclined portion 43 of the base 42 - 43, the capacitance of the conductor 3 decreases, and the capacitance of the sensor electrode 2 also decreases. Then, when the user's hand approaches the inclined portion 43 of the base 42 - 43 again, the capacitance of the conductor 3 increases, and the capacitance of the sensor electrode 2 also increases. The detection device 4 detects this change in the capacitance of the sensor electrode 2, and the capacitance sensor 1 thereby detects the user's touch operation on the detection area 8. Therefore, this detection information is transmitted as a control signal to the control device of the lamp 41 by wire or wirelessly, and the control device of the lamp 41 stops supplying power to the light source to turn off the lamp 41.

[0083] Various design changes are possible. For example, the inclined portion 43 of the base 42-43 is circumferentially divided into a plurality of regions to arrange a plurality of detection regions 8, and a conductor 3 and a module 7 are provided for each detection region 8. Thus, in the lamp 41, when a detection region 8 detects a touch operation by the user, the lamp 41 is turned on; when another detection region 8 detects a touch operation by the user, the lamp 41 is turned off; and when still another detection region 8 detects a touch operation by the user, the light color of the lamp 41 is changed.

[0084] In an example of using the capacitance sensor 1 in the lamp 41, the control component 6 of the detection device 4 replaces the control device of the lamp 41, and the control component 6 can be configured to supply power to the light source to turn the lamp 41 on or off when detecting a touch operation by the user on the detection region 8.

[0085] (5) Wireless earphones Figure 12 An example of using the capacitance sensor 1 in the wireless earphones 51 is shown. In the illustrated example of the wireless earphones 51, the tip portion 53 of the housing 52 is the detection region 8 for detecting a touch operation by the user. The wireless earphones 51 are configured to turn on and off the power in response to the capacitance sensor 1 detecting the action of the user inserting the tip portion 53 of the housing 52 into the ear canal as a touch operation. In the illustrated example, the sensor electrode 2 of the capacitance sensor 1 and the detection device 4 are in the form of a module 7, and the sensor electrode 2 is integrated into the detection device 4.

[0086] The housing 52 is made of, for example, synthetic resin, and the entire inner surface of the tip portion 53 is coated with, for example, a metal plating as the conductor 3. The module 7 is attached to a part of the conductor 3 via a dielectric (such as an adhesive or a double-sided tape 55). The module 7 is provided at one end of the tip portion 53 (i.e., the detection region 8) of the housing 52 opposite to the earpiece 54.

[0087] When the user inserts the tip portion 53 of the wireless earphone 51 into the ear canal, since the conductor covers the entire area of the tip portion 53 (i.e., the detection area 8), the capacitance of the conductor 3 increases, and the capacitance of the sensor electrode 2 also increases. The detection device 4 can detect this change in the capacitance of the sensor electrode 2, and based on this, the electrostatic capacitance sensor 1 detects the touch operation of the user on the detection area 8. This detection information is transmitted as a control signal to the control device that controls the operation of the wireless earphone 51 in a wired or wireless manner, and the control device of the wireless earphone 51 turns on the power of the wireless earphone 51 through known electrical / electronic circuits, switches, etc. When the user removes the wireless earphone 51 from the ear, the capacitance of the conductor 3 decreases, and the capacitance of the sensor electrode 2 also decreases. The detection device 4 detects this change in the capacitance of the sensor electrode 2, and based on this, the electrostatic capacitance sensor 1 detects the release of the touch operation of the user on the detection area 8. This detection information is transmitted as a control signal to the control device of the wireless earphone 51 in a wired or wireless manner, and the control device of the wireless earphone 51 turns off the power of the wireless earphone 51 accordingly.

[0088] In an example of using the electrostatic capacitance sensor 1 in the wireless earphone 51, the control component 6 of the detection device 4 replaces the control device of the wireless earphone 51, and this control component 6 can be configured to turn on and off the power of the wireless earphone 51 when detecting the touch operation of the user on the detection area 8.

[0089] In addition, in an example of using the electrostatic capacitance sensor 1 in the wireless earphone 51, the wireless earphone 51 can be redesigned as a hearing aid.

[0090] (6) Touch switch Figure 13 and Figure 14 shows an example of using the electrostatic capacitance sensor 1 in the touch switch 61, which can be used in, for example, elevators, automatic doors, and touch panels, allowing various function selections to be performed simply by gently touching the device without pressing a button.

[0091] In the illustrated example, the touch switch 61 has one or more sensor electrodes 2 on the upper surface of the printed circuit board 63, and a cover plate 62 provided above the printed circuit board 2. The cover plate 62 is made of, for example, synthetic resin or wood. One or more conductors 3 are provided on the upper surface of the cover plate 62 corresponding to the respective sensor electrodes 2. The conductor 3 is made of, for example, a metal thin film. For example, in Figure 14 the area on the upper surface of the cover plate 62 other than the conductor 3 is formed with a metal thin film 64, and the surface of the touch switch 61 has a metallic flash paint. In Figure 14In this case, a gap is left between the metal thin film 64 and the conductor 3, the metal thin film 64 and the conductor 3 are electrically disconnected from each other, and the metal film 64 is grounded. For example, on the upper surface of the cover plate 62, a non-conductive surface layer 65 (such as a resin film or a resin panel) is provided to cover the conductor 3 and the metal thin film 64. The surface of the touch switch 61, that is, the upper surface of the surface layer 65 in this example, is the detection area 8 for detecting the touch operation of the user, and the position of the corresponding conductor 3 corresponds to various button operation positions of the touch switch 61.

[0092] The capacitance sensor 1 detects that the user's finger touches or approaches any button operation position in the detection area 8 as the user's touch operation. When the user touches or approaches any button operation position in the detection area 8, the capacitance of the conductor 3 at the button operation position increases, and the capacitance of the sensor electrode 2 corresponding to the conductor 3 increases. The detection component 5 of the detection device 4 detects the capacitance change of each sensor electrode 2, thereby detecting the position where the touch operation has been performed in the detection area 8, and outputs a detection signal to the control component 6, indicating which button operation position in the detection area 8 has performed the touch operation. Based on the detection signal, the control component 6 determines whether a touch operation has been performed at any button operation position in the detection area 8, and outputs a control signal to the control device 10 installed in the device to cause the device to execute the function set at the button operation position where the touch operation has been performed.

[0093] Modification description The capacitance sensor of the present disclosure has been described above; however, the above embodiments are merely illustrative and not restrictive. Therefore, the capacitance sensor of the present disclosure is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present disclosure.

[0094] For example, in the above embodiment, an action of detecting that a part of the user's body (such as a finger) touches or approaches the detection area 8 (touch operation) as a detectable object is detected. However, the detectable object may not be a part of the human body, and may be a liquid such as water, for example. For example, as Figure 15 shown, the capacitance sensor 1 of the present disclosure can be used as a water level sensor 71.

[0095] In Figure 15 the water level sensor 71 shown, a part in the height direction of the bottomed cylindrical water tank 72 for storing a liquid (such as water) is the detection area 8 for detecting the water level. The water level sensor 71 is configured to detect whether the liquid level has reached the detection area 8 in response to the action of the capacitance sensor detecting the approach of the liquid to the detection area 8 when the liquid volume increases or decreases. In the illustrated example, the sensor electrode 2 and the detection device 4 of the capacitance sensor 1 are in the form of a module 7, in which the sensor electrode 2 is integrated into the detection device 4.

[0096] The water tank 72 is made of, for example, wood or synthetic resin, and the entire outer surface of the detection area 8 in the water tank 72 is coated with a conductor 3 such as a metal plating. The module 7 is attached to the inner surface of the detection area 8 in the water tank 72 via a dielectric (such as an adhesive or a double-sided tape 73) so as to face a part of the water tank 72. The module 7 is provided at the lower end of the detection area 8. In the height direction of the water tank 72, for example, the entire outer surface of the part other than the detection area 8 may be coated with a metal plating; however, a gap is left between the metal plating and the conductor 3 on the outer surface of the detection area 8, and the metal plating and the conductor 3 are electrically disconnected and preferably grounded.

[0097] When the liquid enters the water tank 72 from an inlet (not shown), the liquid level rises and reaches the lower end of the detection area 8. At this time, as Figure 16 shown, since the conductor 3 covers the entire detection area 8, the capacitance of the conductor 3 increases, and the capacitance of the sensor electrode 2 also increases. The detection device 4 detects this change in the capacitance of the sensor electrode 2, and this detection information is transmitted to the control device of the water level sensor 71 by wire or wirelessly as a control signal. The control device of the water level sensor 71 thereby detects that the liquid in the water tank 72 has been stored to a predetermined height. When the liquid further flows into the water tank 72 and the liquid level is higher than the upper end of the detection area 8, the capacitance of the conductor 3 remains constant, and the capacitance of the sensor electrode 2 also remains constant. This detection information is transmitted to the control device of the water level sensor 71 by wire or wirelessly as a control signal. The control device of the water level sensor 71 thereby detects that the height of the liquid stored in the water tank 72 has been higher than the predetermined height. Thereafter, the liquid is discharged from the water tank 72 through an outlet (not shown), and when the liquid level drops to the upper end of the detection area 8, the capacitance of the conductor 3 decreases, and the capacitance of the sensor electrode 2 decreases. The detection device 4 detects this change in the capacitance of the sensor electrode 2, and this detection information is transmitted to the control device of the water level sensor 71 by wire or wirelessly as a control signal. The control device of the water level sensor 71 thereby detects that the liquid has been stored again to the predetermined height in the water tank 72. When the liquid is further discharged outside the water tank 72 and the liquid level drops below the lower end of the detection area 8, the capacitance of the conductor 3 remains constant, and the capacitance of the sensor electrode 2 also remains constant. This detection information is transmitted to the control device of the water level sensor 71 by wire or wirelessly as a control signal. The control device of the water level sensor 71 thereby detects that the liquid in the water tank 72 has not been stored to the predetermined height.

[0098] In an example where the capacitance sensor 1 is used in the water level sensor 71, the control component 6 of the detection device 4 replaces the control device of the water level sensor 71, and the control component 6 can be configured to detect whether the liquid level in the water tank 72 is at a predetermined height. List of reference numerals

[0099] 1. Capacitive sensor 2. Sensor electrode 3. Conductor 4. Detection device 5. Detection component 6. Control component 7. Module 8. Detection area of the device 9. Detectable object 10. Control device of the device

Claims

1. An electrostatic capacitance sensor, the electrostatic capacitance sensor comprising a sensor electrode and a detection device, the detection device being configured to detect contact or approach of a detectable object relative to a detection area based on a capacitance change of the sensor electrode. The electrostatic capacitance sensor includes a conductor provided in the detection area. The conductor is disposed on a side opposite to the sensor electrode, and there is a gap between the conductor and the sensor electrode or a dielectric is inserted between the conductor and the sensor electrode. Viewed from the direction of the sensor electrode and the conductor facing each other, the area of the conductor is larger than the area of the sensor electrode and a part of the conductor facing the sensor electrode. The detection device includes a detection component and a control component, the detection component being configured to detect a change in a combined capacitance of the capacitance of the conductor and the capacitance of the sensor electrode as a change in the capacitance of the sensor electrode, and The detection component includes a CV amplifier configured to convert a capacitance change into a voltage change, and the control component is configured to detect the contact or approach of the detectable object relative to the detection area based on a detection signal corresponding to a change in the voltage output from the detection component.

2. The electrostatic capacitance sensor according to claim 1, wherein the conductor covers the entire detection area.

3. The electrostatic capacitance sensor according to claim 1, wherein the conductor is composed of any one of conductive ink, conductive resin, metal thin film, metal sheet, metal plate, metal mesh, conductive fabric, conductive knitted fabric, and conductive non-woven fabric.

4. The electrostatic capacitance sensor according to any one of claims 1 to 3, wherein the detection area is a toilet seat, the conductor is provided on the back side of the toilet seat, and the sensor electrode is fixed to a part of the conductor via the dielectric.

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