Contact sensor and radiation heater

Abstract

To detect contact of each of a human body and an object having low thermal conductivity with a simple configuration.SOLUTION: A contact sensor 200 includes: an electrode section 210 including a pair of a first detection electrode 211 and a second detection electrode 212 disposed in parallel mutually on a board 120; a signal input section 220 for applying a first detection signal including an AC signal having a frequency of 1 MHz or higher to the first detection electrode; a detection section 230 for outputting a first output signal expressing first capacitance between the first detection electrode and the second detection electrode; and a determination section 420 for determining contact of a human body or an object when a predetermined condition expressing a change in the first capacitance between the first detection electrode and the second detection electrode is satisfied based on the first output signal.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a contact sensor and a radiant heater. [Background technology]

[0002] Patent Document 1 describes a capacitance type sensor for detecting the approach of a user's feet in a vehicle that opens and closes the door when it detects the approach of the user's feet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-057537 A Summary of the Invention [Problem to be solved by the invention]

[0004] A capacitance sensor as described in Patent Document 1 may be provided in a radiant heater as a sensor for detecting contact with a part of a user's body. Conventionally, in addition to a capacitance sensor that detects contact with a part of a human body in order to prevent burns, radiant heaters have been provided with another sensor that detects contact with an object with low thermal conductivity in order to prevent an excessive rise in surface temperature.

[0005] The reason why it was necessary to use different sensors to detect contact between the human body and an object with low thermal conductivity is that the relative dielectric constant of the human body is significantly different from that of an insulator. For example, when detecting contact between the human body and an object with low thermal conductivity using a capacitance sensor, a threshold value based on the relative dielectric constant of the object with low thermal conductivity is set as a threshold value for the capacitance used to detect contact. In this case, even if only a part of the human body is in close proximity, it may be erroneously detected as contact. As a result, the temperature of the heater is lowered or the heater operation is stopped frequently, reducing comfort. Therefore, a technology for detecting contact between the human body and an object with low thermal conductivity with a simple configuration has been desired. [Means for solving the problem]

[0006] According to one embodiment of the present disclosure, there is provided a contact sensor, the contact sensor (200) including: an electrode section (210) including a pair of a first detection electrode (211) and a second detection electrode (212) arranged parallel to each other on a substrate (120); a signal input section (220) for applying a first detection signal including an AC signal having a frequency of 1 MHz or more to the first detection electrode; a detection section (230) for outputting a first output signal representing a first capacitance between the first detection electrode and the second detection electrode; and a determination section (420) for determining that a human body or an object has come into contact with the contact sensor when a predetermined condition is satisfied that represents a change in the first capacitance between the first detection electrode and the second detection electrode based on the first output signal.

[0007] The electrical characteristics of the human body include a characteristic that the relative dielectric constant at high frequencies is lower than that at low frequencies. Therefore, by using a first detection signal of 1 MHz or more as the first detection signal, the detection sensitivity of the contact sensor for the contact of the human body can be reduced compared to an embodiment using a signal having a frequency lower than that of the first detection signal. This allows the detection sensitivity of the capacitive sensor for the contact of the human body to be closer to the detection sensitivity for an object with low thermal conductivity. Therefore, it is possible to detect the contact of the human body and the object with low thermal conductivity without providing two types of sensors, one for detecting the contact of the human body and the other for detecting the object with low thermal conductivity, as in the conventional case. Therefore, it is possible to detect the contact of the human body and the object with low thermal conductivity with a simple configuration. [Brief description of the drawings]

[0008] [Figure 1] FIG. 4 is an explanatory diagram showing an example of the arrangement of radiant heaters. [Diagram 2] FIG. 2 is a block diagram showing a schematic configuration of a radiant heater. [Diagram 3] FIG. 2 is an explanatory diagram illustrating a configuration of a heater main body according to the first embodiment. [Figure 4] FIG. 11 is an explanatory diagram illustrating the configuration of a heater main body according to a second embodiment. [Diagram 5] 13 is a flowchart of a process for detecting contact between a human body and an object according to a second embodiment. [Figure 6] 13 is a flowchart of a process of energization control after contact detection according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A. First embodiment: As shown in Fig. 1, a radiant heater 10 is used as a heating device for a vehicle. The radiant heater 10 is provided on the surface of an internal panel IP disposed below a steering wheel SW. More specifically, the radiant heater 10 is disposed in a position facing the lower legs of an occupant VP when the occupant VP is seated in a seat VC.

[0010] 2, the radiant heater 10 includes a heater main body 100, a detection unit 200, a power supply unit 300, and a control unit 400. The detection unit 200 is also called a contact sensor.

[0011] 3, the heater body 100 includes a first heating element 110 and a first substrate 120. The first substrate 120 is also called a substrate.

[0012] The first heating element 110 is formed from a layer of a metal material such as copper or an alloy containing copper. The first heating element 110 generates heat when electricity is applied. The first heating element 110 is composed of a copper wire formed by patterning a copper foil on the first substrate 120. Note that the conductive material forming the first heating element 110 is not limited to copper. The first heating element 110 is also called a heating part. A heater driving part 410 of the control part 400 described later adjusts the supply of power to the first heating element 110 so that the temperature of the first heating element 110 becomes a set temperature. For example, the set temperature is 120 degrees.

[0013] A contact provided at one end of the first heating element 110 and a contact provided at the other end are connected to a connector CN1. The connector CN1 is connected to a connector (not shown) provided in the control unit 400 via a wire (not shown). In this manner, the first heating element 110 is electrically connected to the heater driving unit 410 of the control unit 400.

[0014] The first substrate 120 is a flexible substrate made of an insulating material. The first heating element 110 is disposed on the upper surface (+Z side) of the first substrate 120.

[0015] Since the heater main body 100 is configured in a flexible sheet shape, the shape of the heater main body 100 can be deformed. Therefore, there is a high degree of freedom in the installation location of the heater main body 100. Note that it is not assumed that the heater main body 100 will be deformed by application of an external force after the heater main body 100 is installed in the vehicle.

[0016] 2, the detection unit 200 functions as a capacitance sensor for detecting contact of a human body or an object with the heater main body 100. The detection unit 200 may be a self-capacitance sensor or a mutual capacitance sensor.

[0017] The detection unit 200 includes an electrode unit 210, a signal input unit 220, and a capacitance detection unit 230. The reason why the detection unit 200 detects contact of a human body or an object is as follows. For example, when an object with high thermal insulation properties comes into contact with the first heating element 110, heat may build up in the contact area. For this reason, it is necessary to suppress excessive temperature rise. Also, when a human body comes into contact with the first heating element 110, burns may occur. Therefore, it is necessary to protect the occupant VP.

[0018] As shown in FIG. 3, the electrode unit 210 includes a first detection electrode 211 and a second detection electrode 212. The first detection electrode 211 and the second detection electrode 212 are arranged parallel to each other on the first substrate 120. The first detection electrode 211 and the second detection electrode 212 extend along the same direction (Y-axis direction). The electrode unit 210 and the first heating element 110 are arranged in close proximity to each other. In the example shown in FIG. 3, the first heating element 110 is arranged so as to surround the first detection electrode 211 and the second detection electrode 212. The first detection electrode 211 and the second detection electrode 212 are made of copper wires formed by copper foil patterning. Note that the conductive material forming the first detection electrode 211 and the second detection electrode 212 is not limited to copper. One end of each of the first detection electrode 211 and the second detection electrode 212 is connected to the connector CN1. Therefore, as shown in FIG. 2, the electrode section 210 is electrically connected to a signal input section 220 and a capacitance detection section 230 of the control section 400.

[0019] The signal input unit 220 shown in FIG. 2 applies a first detection signal to the first detection electrode 211. In this embodiment, a high-frequency AC signal is used as the first detection signal. In this specification, a high-frequency AC signal refers to an AC signal of 1 MHz or more. In this embodiment, the first detection signal is an AC signal having a frequency of 10 MHz or more and 100 MHz or less. The first detection signal is a sine wave AC signal. When the signal input unit 220 receives a command to start outputting the first detection signal from the calculation unit 420 described later, the signal input unit 220 applies the first detection signal to the first detection electrode 211. The signal input unit 220 continues to output the first detection signal until it receives a command to stop outputting the first detection signal from the calculation unit 420.

[0020] The capacitance detection unit 230 detects the capacitance between the first detection electrode 211 and the second detection electrode 212 (first capacitance).

[0021] When the detection unit 200 is a self-capacitance type sensor, the first detection electrode 211, the second detection electrode 212, or both the first detection electrode 211 and the second detection electrode 212 are detection electrodes. When a first detection signal is applied to the first detection electrode 211, a parasitic capacitance occurs between the first detection electrode 211 and the GND. For example, when a person's finger approaches or touches the first detection electrode 211, a capacitance occurs between the first detection electrode 211 and the person's finger. In the self-capacitance type, an increase in the capacitance occurring between the first detection electrode 211 and the person's finger is detected. Specifically, the capacitance detection unit 230 detects the capacitance between the first detection electrode 211 and the second detection electrode 212, which is a ground electrode, using a voltage to ground based on a voltage signal output from the first detection electrode 211 and the amount of current per unit time flowing through the first detection electrode 211. The capacitance detection section 230 outputs a first output signal representing the capacitance between the first detection electrode 211 and the second detection electrode 212 to the calculation section 420 .

[0022] When the detection unit 200 is a mutual capacitance type sensor, the first detection electrode 211 is a transmission electrode, and the second detection electrode 212 is a measurement electrode. When a first detection signal is applied to the first detection electrode 211, an electric field is generated between the first detection electrode 211 and the second detection electrode 212. For example, when a person's finger approaches or touches the first detection electrode 211, a part of the electric field moves to the person's body, and the capacitance between the first detection electrode 211 and the second detection electrode 212 decreases. In the mutual capacitance type, the decrease in the capacitance between the first detection electrode 211 and the second detection electrode 212 is detected. Specifically, the capacitance detection unit 230 detects the capacitance between the first detection electrode 211 and the second detection electrode 212, which is a ground electrode, using the potential difference between the first detection electrode 211 and the second detection electrode 212 and the amount of current per unit time flowing through the first detection electrode 211. The capacitance detection section 230 outputs a first output signal representing the capacitance between the first detection electrode 211 and the second detection electrode 212 to the calculation section 420 .

[0023] The power supply unit 300 appropriately converts the voltage of the power supplied from a battery (not shown) provided in the vehicle, and supplies the voltage-converted power to a heater driving unit 410, which will be described later.

[0024] The control unit 400 controls the power supply to the heater main body 100. The control unit 400 is also called a power supply control unit. The control unit 400 includes a heater driving unit 410 and a calculation unit 420.

[0025] The heater driving unit 410 includes semiconductor elements such as a thyristor and an IGBT (Insulated Gate Bipolar Transistor) to switch the electrical connection between the power supply unit 300 and the first heating element 110. The heater driving unit 410 switches the power supply to the first heating element 110 on and off in response to a command received from the calculation unit 420. While the heater driving unit 410 electrically connects the power supply unit 300 and the electrical wiring 130, a current flows to the first heating element by the power supplied from the power supply unit 300. When the first heating element 110 is energized, a current flows to the first heating element at an output voltage determined by the calculation process of the calculation unit 420. While the heater driving unit 410 cuts off the electrical connection between the power supply unit 300 and the first heating element 110, no current flows to the first heating element. The heater driving unit 410 controls the amount of current flow in response to a command received from the calculation unit 420.

[0026] The calculation unit 420 is a microcomputer including a processor and a memory. For example, when the calculation unit 420 receives a command to start the operation of the radiant heater 10 from an ECU (Electronic Control Unit) (not shown), the calculation unit 420 first causes the signal input unit 220 to start outputting a first detection signal. This is to detect contact with the heater main body 100. After confirming that a person is not touching the heater main body 100 based on the first output signal output by the capacitance detection unit 230, the calculation unit 420 outputs a command to turn on the power supply to the first heating element 110 to the heater driving unit 410. As a result, the power supply to the first heating element 110 is started. In addition, when the calculation unit 420 receives a command to stop the operation of the radiant heater 10 from an ECU (not shown), the calculation unit 420 outputs a command to turn off the power supply to the first heating element 110 to the heater driving unit 410.

[0027] In this embodiment, the calculation unit 420 determines that a human body or an object has come into contact with the first heating element 110 when a predetermined condition indicating that the detected first capacitance has changed is satisfied. In this specification, the object refers to a dielectric material. The object does not include a human. The calculation unit 420 is also referred to as a determination unit.

[0028] In this embodiment, the first condition is that the amount of change in the first capacitance within a predetermined time is equal to or greater than a predetermined threshold value Th. The predetermined time is, for example, 100 milliseconds. When the first detection signal is applied and there is no contact with a person or an object, the capacitance between the first detection electrode 211 and the second detection electrode 212 is known. The threshold value Th is determined based on this known capacitance.

[0029] When the calculation unit 420 determines that a human body or an object has come into contact with the first heating element 110, it outputs a command to the heater driving unit 410 to turn off the power supply to the first heating element 110. Thus, the power supply to the first heating element 110 is stopped.

[0030] The calculation unit 420 stops the supply of electricity to the first heating element 110 while the human body or object is in contact with the first heating element 110. After stopping the supply of electricity to the first heating element 110, when the calculation unit 420 determines that the human body or object is no longer in contact with the first heating element 110, it outputs a command to the heater driving unit 410 to turn on the supply of electricity to the first heating element 110. Thus, the supply of electricity to the first heating element 110 is resumed.

[0031] As mentioned above, the relative dielectric constant of the human body is significantly different from that of an insulator, so the amount of change in capacitance caused by contact with the human body is larger than the amount of change in capacitance caused by contact with an insulator, etc. For example, if a threshold value based on the relative dielectric constant of an object with low thermal conductivity is set as the threshold value for capacitance used to detect contact, the amount of change in capacitance may exceed the threshold value just because a part of the human body is in close proximity. Therefore, even if no part of the human body is in contact, it may be erroneously detected as having been in contact.

[0032] In this embodiment, a high-frequency AC signal is used as the first detection signal, taking into consideration the electrical characteristics of the human body, in which the relative dielectric constant at high frequencies is lower than that at low frequencies. By using a high-frequency AC signal, the amount of change in capacitance caused by contact with the human body can be reduced compared to an embodiment using a low-frequency AC signal. In this way, the detection sensitivity of the detection unit 200, which is a capacitance-type sensor, to contact with the human body is reduced. As a result, in the capacitance-type sensor, the detection sensitivity of the human contact can be made closer to the detection sensitivity of an object with low thermal conductivity. Therefore, the same capacitance-type sensor can detect contact with the human body and an object with low thermal conductivity. Unlike the conventional technology, there is no need to provide two types of sensors, a sensor for detecting contact with the human body and a sensor for detecting an object with low thermal conductivity. Therefore, the contact with the human body and an object with low thermal conductivity can be detected with a simple configuration.

[0033] B. Second embodiment: In the second embodiment, the configuration different from the first embodiment will be mainly described. The description of the same configuration as the first embodiment will be omitted. In the second embodiment, an aspect of individually detecting the contact of a human body or an object will be described.

[0034] The heater body 100 is an electric heater, similar to the first embodiment.

[0035] As shown in FIG. 4, in the second embodiment, the electrode unit 210 includes a third detection electrode 213 and a fourth detection electrode 214 in addition to the first detection electrode 211 and the second detection electrode 212. The first detection electrode 211 and the second detection electrode 212 are arranged parallel to each other on the first substrate 120. The third detection electrode 213 and the fourth detection electrode 214 are arranged parallel to each other on the first substrate 120. The first detection electrode 211, the second detection electrode 212, the third detection electrode 213, and the fourth detection electrode 214 extend along the same direction (Y-axis direction). The first heating element 110 is arranged so as to surround the first detection electrode 211, the second detection electrode 212, the third detection electrode 213, and the fourth detection electrode 214. The first detection electrode 211, the second detection electrode 212, the third detection electrode 213, and the fourth detection electrode 214 are connected to the detection unit 200 via a connector CN1.

[0036] 2, the signal input unit 220 applies a first detection signal to the first detection electrode 211. The first detection signal is an AC signal having a frequency of 10 MHz or more and 100 MHz or less, similar to the first embodiment. The first detection signal is a sine wave AC signal.

[0037] Furthermore, the signal input unit 220 applies a second detection signal to the third detection electrode 213. In this embodiment, a low-frequency AC signal is used as the second detection signal. In this specification, a low-frequency AC signal refers to an AC signal of 100 kHz or less. In this embodiment, the second detection signal is an AC signal having a frequency of 1 kHz or more and 100 kHz or less. The second detection signal is a square-wave AC signal. In this embodiment, a square-wave signal is used as the second detection signal, so that the signal generating circuit of the second detection signal can be simplified. Compared to an aspect in which a sine wave is used for both the first detection signal and the second detection signal, the configuration of the signal generating circuit can be simplified.

[0038] For example, when signal input section 220 receives a command from calculation section 420 to start outputting the first detection signal and the second detection signal, it applies the first detection signal to first detection electrode 211 and applies the second detection signal to third detection electrode 213. Signal input section 220 continues outputting the first detection signal and the second detection signal until it receives a command from calculation section 420 to stop outputting the first detection signal and the second detection signal.

[0039] The capacitance detection unit 230 detects the capacitance (first capacitance) between the first detection electrode 211 and the second detection electrode 212. The capacitance detection unit 230 outputs a first output signal representing the capacitance between the first detection electrode 211 and the second detection electrode 212 to the calculation unit 420. Furthermore, the capacitance detection unit 230 detects the capacitance (second capacitance) between the third detection electrode 213 and the fourth detection electrode 214. The capacitance detection unit 230 outputs a second output signal representing the capacitance between the third detection electrode 213 and the fourth detection electrode 214 to the calculation unit 420.

[0040] The configurations of the power supply unit 300 and the heater driving unit 410 of the control unit 400 are similar to those in the first embodiment.

[0041] The calculation unit 420 is a microcomputer equipped with a processor and a memory. For example, when the calculation unit 420 receives a command from an ECU (not shown) to start the operation of the radiant heater 10, the calculation unit 420 outputs a command to turn on the power supply to the first heating element 110 to the heater driving unit 410. Furthermore, when the calculation unit 420 receives a command to start the operation of the radiant heater 10, the calculation unit 420 causes the signal input unit 220 to start outputting the first detection signal and the second detection signal. This is to detect contact with the heater main body 100.

[0042] When the calculation unit 420 receives a command from an ECU (not shown) to stop the operation of the radiant heater 10 , it outputs a command to the heater drive unit 410 to turn off the power supply to the first heating element 110 .

[0043] The calculation unit 420 determines that an object other than a human body has come into contact with the first heating element 110 when the amount of change in the first capacitance within a predetermined time period becomes equal to or greater than a first threshold value Th21. When the first detection signal is applied and there is no contact of an object other than a human body, the capacitance between the first detection electrode 211 and the second detection electrode 212 is known. The first threshold value Th21 is determined based on this known capacitance. The amount of change in the first capacitance becoming equal to or greater than the first threshold value Th21 is the first condition for detecting contact of an object other than a human body.

[0044] When the calculation unit 420 determines that an object other than a human body has come into contact with the first heating element 110, it outputs a command to the heater driving unit 410 to reduce the amount of electricity supplied to the first heating element 110 from a reference value in order to reduce the amount of electricity supplied to the first heating element 110. The reference value represents the amount of electricity required to maintain the temperature of the first heating element 110 at the set temperature. Thus, the temperature of the first heating element 110 decreases.

[0045] After reducing the amount of electricity supplied to the first heating element 110, when the calculation unit 420 determines that the object is no longer in contact with the first heating element 110 based on the change in the first capacitance, the calculation unit 420 outputs a command to the heater driving unit 410 to return the amount of electricity to the reference value. Thus, the temperature of the first heating element 110 rises.

[0046] Furthermore, the calculation unit 420 determines that a human body has come into contact with the first heating element 110 when the amount of change in the second capacitance within a predetermined time period is equal to or greater than a second threshold value Th22. When the second detection signal is applied and there is no contact with an object other than a human body, the capacitance between the third detection electrode 213 and the fourth detection electrode 214 is known. The second threshold value Th22 is determined based on this known capacitance. The amount of change in the second capacitance being equal to or greater than the second threshold value Th22 is the second condition for detecting contact with a human body.

[0047] When the calculation unit 420 determines that the human body has come into contact with the first heating element 110, it outputs a command to stop the energization to the heater driving unit 410 in order to stop the energization of the first heating element 110. Thus, the energization of the first heating element 110 is stopped. Furthermore, after the energization of the first heating element 110 is stopped, when the calculation unit 420 determines that the human body is no longer in contact with the first heating element 110 based on a change in the second capacitance, it outputs a command to turn on the energization of the first heating element 110 to the heater driving unit 410. Thus, the energization of the first heating element 110 is resumed.

[0048] Here, between the control when the first condition is satisfied, i.e., when contact of an object other than a human body is detected, and the control when the second condition is satisfied, i.e., when contact of a human body is detected, the control when the second condition is satisfied has a higher priority. Therefore, when contact of an object other than a human body and contact of a human body are detected simultaneously, the calculation unit 420 causes the heater driving unit 410 to stop the supply of electricity to the first heating element 110. In this case, the control to reduce the amount of electricity supplied to the first heating element 110 is not performed.

[0049] In addition, after control to reduce the amount of electricity supplied to the first heating element 110 has been initiated due to the detection of contact by an object other than a human body, if contact by a human body is detected, the calculation unit 420 causes the heater driving unit 410 to stop supplying electricity to the first heating element 110.

[0050] Furthermore, when contact of an object other than a human body is detected after control to stop the supply of electricity to the first heating element 110 is started due to detection of contact by a human body, the calculation unit 420 continues to stop the supply of electricity to the first heating element 110. In this case, control to reduce the amount of electricity supplied to the first heating element 110 is not performed.

[0051] FIG 5 shows the process of contact detection between a human body and an object. FIG 6 shows the process of power supply control after contact detection. In step S101, the calculation unit 420 sets the first determination flag F1 and the second determination flag F2 to an initial value = "false". The first determination flag F1 is a variable that indicates whether or not the first condition is satisfied. The second determination flag F2 is a variable that indicates whether or not the second condition is satisfied.

[0052] In step S102, the capacitance detection unit 230 detects the second capacitance between the third detection electrode 213 and the fourth detection electrode 214.

[0053] In step S103, the calculation unit 420 determines whether or not the second condition is satisfied using the detected second capacitance. If the second condition is satisfied, that is, if contact with a person's body is detected (step S103; YES), step S104 is executed. If the second condition is not satisfied (step S103; NO), step S105 is executed.

[0054] In step S104, the calculation unit 420 sets the second determination flag F2 to "true."

[0055] In step S105, the calculation unit 420 sets the second determination flag F2 to "false."

[0056] In step S 106 , the capacitance detection unit 230 detects the first capacitance between the first detection electrode 211 and the second detection electrode 212 .

[0057] In step S107, the calculation unit 420 determines whether or not the first condition is satisfied using the detected first capacitance. If the first condition is satisfied, that is, if contact of an object is detected (step S107; YES), step S108 is executed. If the first condition is not satisfied (step S107; NO), step S109 is executed.

[0058] In step S108, the calculation unit 420 sets the first determination flag F1 to "true."

[0059] In step S109, the calculation unit 420 sets the first determination flag F1 to "false."

[0060] 6, in step S110, the calculation unit 420 determines whether or not the second determination flag F2 is "true." If the second determination flag F2 is "true" (step S110; YES), the process of step S111 is executed. On the other hand, if the second determination flag F2 is "false" (step S110; NO), the process of step S112 is executed.

[0061] In step S111, the calculation unit 420 stops the power supply to the first heating element 110 by issuing a command to the heater driving unit 410 to stop the power supply. Note that if the second determination flag F2 is "true", the process of step S111 is executed regardless of the value of the first determination flag F1. This is because, as described above, the priority of the control when the second condition is satisfied is higher than the priority of the control when the first condition is satisfied.

[0062] In step S112, the calculation unit 420 determines whether or not the first determination flag F1 is "true." If the first determination flag F1 is "true" (step S112; YES), the process proceeds to step S113. On the other hand, if the first determination flag F1 is "false" (step S112; NO), the process proceeds to step S114.

[0063] In step S113, the calculation unit 420 reduces the amount of electricity supplied to the first heating element 110 by issuing a command to the heater driving unit 410 to reduce the amount of electricity supplied thereto.

[0064] In step S114, the calculation unit 420 determines whether or not the power supply to the first heating element 110 is restricted. The power supply being restricted means that the power supply is stopped or that the amount of power supply is reduced below a reference value. If the power supply to the first heating element 110 is restricted (step S114; YES), the process of step S115 is executed. On the other hand, if the power supply to the first heating element 110 is not restricted (step S114; NO), the process of step S116 is executed.

[0065] In step S115, the calculation unit 420 issues a command to the heater driving unit 410 to energize the first heating element 110, thereby restarting the energization of the first heating element 110.

[0066] In step S116, if the processing should be ended (step S116; YES), the calculation unit 420 ends the processing shown in Fig. 6. For example, if an instruction to end the processing is received from an ECU (not shown), the calculation unit 420 ends the processing shown in Fig. 6. On the other hand, if the processing is to be continued (step S116; NO), the processing of step S102 shown in Fig. 5 is executed again. The above is the flow of a series of processes related to contact detection and power supply control.

[0067] In this embodiment, the second detection signal, which is a low-frequency AC signal, is used to detect contact with a human body, and the first detection signal, which is a high-frequency AC signal, is used to detect contact with an object. When comparing the frequency characteristics of the dielectric constant of a human body with the frequency characteristics of the dielectric constant of an object other than a human body, the degree of decrease in the dielectric constant of the human body as the frequency increases is greater than that of an object. The dielectric constant of an object does not change significantly even if the frequency of the detection signal changes. In addition, the dielectric constant of a human body has a characteristic that the dielectric constant at high frequencies is lower than that at low frequencies. For this reason, in this embodiment, a low-frequency detection signal is used to detect a human body, and a high-frequency detection signal is used to detect an object. In this way, it is easy to distinguish and detect contact with an object from contact with a human body.

[0068] C. Third embodiment: In the third embodiment, the configuration different from the first embodiment will be mainly described. The description of the same configuration as the first embodiment will be omitted. In the third embodiment, the aspect of individually detecting the contact of a human body or an object will be described.

[0069] In this embodiment, similarly to the first embodiment, the electrode unit 210 includes a first detection electrode 211 and a second detection electrode 212. The configuration of the first detection electrode 211 and the second detection electrode 212, such as the arrangement on the first substrate 120, is similar to that of the first embodiment, as shown in FIG.

[0070] 2 applies a third detection signal to the first detection electrode 211. The third detection signal is a signal generated by synthesizing a low-frequency AC signal and a high-frequency AC signal. More specifically, the third detection signal is a signal obtained by superimposing a low-frequency AC signal LS1, which is a signal having a frequency of 1 kHz or more and 100 kHz or less, on a high-frequency AC signal HS1, which is a signal having a frequency of 10 MHz or more and 100 MHz or less.

[0071] The capacitance detection unit 230 first separates the electrical signal (measurement signal) output from the first detection electrode 211 into a signal HS2 of a high-frequency component having a frequency of 10 MHz or more and 100 MHz or less, and a signal LS2 of a low-frequency component having a frequency of 1 kHz or more and 100 kHz or less.

[0072] The calculation unit 420 uses the high-frequency component signal HS2 to determine whether or not an object other than a human body has come into contact with the first heating element 110. The calculation unit 420 determines that an object other than a human body has come into contact with the first heating element 110 when the amount of change in capacitance represented by the high-frequency component signal HS2 is equal to or greater than a predetermined threshold value Th31.

[0073] The calculation unit 420 uses the low-frequency component signal LS2 to determine whether or not a human body has come into contact with the first heating element 110. The calculation unit 420 determines that a human body has come into contact with the first heating element 110 when the amount of change in capacitance represented by the low-frequency component signal LS2 is equal to or greater than a predetermined threshold value Th32.

[0074] As described above, a signal obtained by superimposing a low-frequency AC signal on a high-frequency AC signal is used as the detection signal, so that contact with an object and contact with a human body can be distinguished and detected with a simpler configuration than an embodiment having two pairs of electrodes.

[0075] D. Fourth embodiment: In the fourth embodiment, the configuration different from the first embodiment will be mainly described. The description of the same configuration as the first embodiment will be omitted. In the fourth embodiment, the aspect of individually detecting the contact of a human body or an object will be described.

[0076] In this embodiment, similarly to the first embodiment, the electrode unit 210 includes a first detection electrode 211 and a second detection electrode 212. The configuration of the first detection electrode 211 and the second detection electrode 212, such as the arrangement on the first substrate 120, is similar to that of the first embodiment, as shown in FIG.

[0077] 2, during a first period, the signal input unit 220 applies a high-frequency AC signal HS3, which is a signal having a frequency of 10 MHz or more and 100 MHz or less, to the first detection electrode 211. During a second period following the first period, the signal input unit 220 applies a low-frequency AC signal LS3, which is a signal having a frequency of 1 kHz or more and 100 kHz or less, to the first detection electrode 211. The signal input unit 220 repeatedly applies the high-frequency AC signal HS3 and the low-frequency AC signal LS3 alternately to the first detection electrode 211.

[0078] The capacitance detection unit 230 detects the capacitance between the first detection electrode 211 and the second detection electrode 212 in a first period. The capacitance detection unit 230 detects the capacitance between the first detection electrode 211 and the second detection electrode 212 in a second period.

[0079] The calculation unit 420 uses the detected change in capacitance during the first period to determine whether or not an object other than a human body has come into contact with the first heating element 110. When the change in capacitance during the first period is equal to or greater than a predetermined threshold value Th41, the calculation unit 420 determines that an object other than a human body has come into contact with the first heating element 110.

[0080] The calculation unit 420 uses the detected change in capacitance during the second period to determine whether or not the human body has come into contact with the first heating element 110. The calculation unit 420 determines that the human body has come into contact with the first heating element 110 when the change in capacitance during the second period is equal to or greater than a predetermined threshold value Th42.

[0081] In this embodiment, by switching the frequency of the detection signal applied to the first detection electrode 211 in a time series, it is possible to distinguish between contact by an object and contact by a human body and to detect this with a simpler configuration than an embodiment having two pairs of electrodes.

[0082] E. Other embodiments: E1. Alternative embodiment 1: In the first embodiment, an example has been described in which power supply to the first heating element 110 is stopped while a person's body or an object is in contact with the first heating element 110. However, power supply to the first heating element 110 may be stopped while a person's body or an object is in contact with the first heating element 110. Alternatively, control may be performed to reduce the amount of power supplied to the first heating element 110 while a person's body or an object is in contact with the first heating element 110.

[0083] In the second embodiment, an example has been described in which the temperature of the first heating element 110 is reduced when it is detected that an object is in contact with the first heating element 110. Alternatively, when it is detected that an object is in contact with the first heating element 110, the control unit 400 may stop the supply of electricity to the first heating element 110.

[0084] E2. Alternative embodiment 2: In the second embodiment, an example has been described in which, when it is detected that a human body is in contact with the first heating element 110, the power supply to the first heating element 110 is stopped. Alternatively, when it is detected that a human body is in contact with the first heating element 110, the control unit 400 may change the amount of power supplied to the first heating element 110 so that the temperature of the first heating element 110 becomes a first temperature lower than a set temperature. For example, the first temperature is set to a temperature lower than 60 degrees. Specifically, the control unit 400 reduces the amount of power supplied to the first heating element 110 to a first power supply lower than a reference value. By setting the temperature of the first heating element 110 to a temperature lower than 60 degrees, which is a temperature at which a burn is instantly caused by contact, it is possible to prevent a part of a human body from touching the first heating element 110 and being burned.

[0085] In the second embodiment, an example has been described in which the temperature of the first heating element 110 is reduced when it is detected that an object is in contact with the first heating element 110. When it is detected that an object is in contact with the first heating element 110, the control unit 400 may change the amount of electricity supplied to the first heating element 110 so that the temperature of the first heating element 110 becomes a second temperature that is lower than a set temperature and higher than the first temperature. For example, the second temperature is set to a temperature of 60 degrees or higher. Specifically, the control unit 400 reduces the amount of electricity supplied to the first heating element 110 to a second amount of electricity that is lower than a reference value. The second amount of electricity is higher than the first amount of electricity.

[0086] E3. Alternative embodiment 3: In the first embodiment, an example has been described in which the first detection signal is an AC signal having a frequency of 10 MHz or more and 100 MHz or less. However, the first detection signal may be an AC signal having a frequency of 1 MHz or more. Similarly, the high frequency AC signal HS1 according to the third embodiment and the high frequency AC signal HS3 according to the fourth embodiment may be an AC signal having a frequency of 1 MHz or more.

[0087] In the second embodiment, an example has been described in which the second detection signal is an AC signal having a frequency of 1 kHz or more and 100 kHz or less. However, the second detection signal may be any AC signal having a frequency of 100 kHz or less. Similarly, the low-frequency AC signal LS1 according to the third embodiment and the low-frequency AC signal LS3 according to the fourth embodiment may be any AC signal having a frequency of 100 kHz or less.

[0088] E4. Alternative embodiment 4: In the first and second embodiments, examples have been described in which the heater main body 100 is an electric heater, but the heater main body 100 according to the second embodiment may be a PTC heater. In the third and fourth embodiments, the heater main body 100 may be a PTC heater or an electric heater. While a human body or an object is in contact with the first heating element 110, the power supply to the first heating element 110 is stopped. This is because when the heater main body 100 is a PTC heater, the temperature cannot be adjusted according to the amount of power supplied.

[0089] E5. Alternative embodiment 5: In the first embodiment, the radiant heater 10 used as a heating device for a vehicle has been described, but the radiant heater 10 is not limited to being used as a heating device for a vehicle. For example, the radiant heater 10 may be a heating device used indoors in a house or the like.

[0090] Furthermore, the contact sensor constituted by the detection unit 200 and the calculation unit 420 described in the first embodiment may be used to detect contact in devices other than the radiant heater 10.

[0091] E6. Alternative Embodiment 6: In the second embodiment, an example has been described in which a sine wave AC signal is used as the first detection signal and a square wave AC signal is used as the second detection signal. However, a sine wave AC signal may be used for both the first detection signal and the second detection signal.

[0092] E7. Alternative Embodiment 7: In the first and second embodiments, an example has been described in which the electrode section 210 is arranged in the inner region surrounded by the first heating element 110 so as to surround the electrode section 210. However, the electrode section 210 may be arranged at any position as long as it is in the vicinity of the first heating element 110. Moreover, the first heating element 110 may also be arranged at any position on the first substrate 120 in any shape.

[0093] In the first embodiment, an example has been described in which the first substrate 120 on which the electrode section 210 is arranged is a flexible substrate made of an insulating material, and the electrical wiring 130 is formed in a film shape. However, the heater main body 100 does not have to be configured in a flexible sheet shape. In this case, the first substrate 120 may be a rigid substrate. The electrical wiring 130 does not have to be formed in a film shape.

[0094] The present disclosure is not limited to the above-mentioned embodiment, and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention column can be appropriately replaced or combined to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if the technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0095] Reference Signs List 10...radiant heater, 100...heater main body, 110...first heating element, 120...first substrate, 210...electrode section, 211...first detection electrode, 212...second detection electrode, 213...third detection electrode, 214...fourth detection electrode, 220...signal input section, 230...capacitance detection section, 420...arithmetic section

Claims

1. A contact sensor (200), An electrode portion (210) including a pair of a first detection electrode (211) and a second detection electrode (212) arranged parallel to each other on a substrate (120); a signal input unit (220) for applying a first detection signal including an AC signal having a frequency of 1 MHz or more to the first detection electrode; a detection unit (230) that outputs a first output signal representing a first capacitance between the first detection electrode and the second detection electrode; a determination unit (420) that determines that a human body or an object has come into contact when a predetermined condition indicating that the first capacitance between the first detection electrode and the second detection electrode has changed is satisfied based on the first output signal; A contact sensor comprising:

2. 2. The contact sensor according to claim 1, The electrode portion further includes a pair of a third detection electrode (213) and a fourth detection electrode (214) arranged parallel to each other on the substrate, The signal input unit further applies a second detection signal including an AC signal having a frequency of 100 kHz or less to the third detection electrode; the detection unit detects a second output signal representing a second capacitance between the third detection electrode and the fourth detection electrode; The determination unit is determining, based on the first output signal, that a non-human object has come into contact when an amount of change in the first capacitance between the first detection electrode and the second detection electrode becomes equal to or greater than a first threshold value that is determined in advance for contact by an object; when a change amount of the second capacitance between the third detection electrode and the fourth detection electrode becomes equal to or greater than a second threshold value that is predetermined for contact by a human body based on the second output signal, it is determined that a human body has come into contact. Contact sensor.

3. 3. The contact sensor according to claim 2, The signal input unit includes: applying a sine wave AC signal as the first detection signal to the first detection electrode; applying a square wave AC signal as the second detection signal to the third detection electrode; Contact sensor.

4. 3. The contact sensor according to claim 2, The signal input unit includes: applying a sine wave AC signal as the first detection signal to the first detection electrode; applying a sine wave AC signal as the second detection signal to the second detection electrode; Contact sensor.

5. 2. The contact sensor according to claim 1, the signal input unit applies a signal obtained by superimposing a low-frequency AC signal having a frequency of 100 kHz or less on a high-frequency AC signal having a frequency of 1 MHz or more to the first detection electrode as a detection signal; The detection unit separates a measurement signal representing the first capacitance between the first detection electrode and the second detection electrode into a high-frequency component and a low-frequency component; the determination unit detects contact of an object using the high-frequency components, and detects contact of a human body using the low-frequency components. Contact sensor.

6. 2. The contact sensor according to claim 1, the signal input unit repeatedly applies a high-frequency AC signal having a frequency of 1 MHz or more to the first detection electrode during a first period, and applies a low-frequency AC signal having a frequency of 100 kHz or less to the first detection electrode during a second period following the first period; The detection unit is Detecting the first capacitance between the first detection electrode and the second detection electrode during the first period; detecting the first capacitance between the first detection electrode and the second detection electrode during the second period; The determination unit is determining whether or not an object is in contact with the sensor based on the detected first capacitance during the first period; determining whether or not a human body is in contact with the sensor based on the detected first capacitance during the second period; Contact sensor.

7. A radiant heater (10) comprising the contact sensor according to any one of claims 1 to 6, A heat generating portion (110) disposed on the substrate (120) and generating heat when current is applied; A current control unit (400) that applies current to the heat generating unit; Equipped with When the determination unit determines that a human body or an object has come into contact with the heat generating unit, the power supply control unit reduces the amount of power supplied to the heat generating unit to a value lower than a reference value required to maintain the temperature of the heat generating unit at a set temperature, or stops power supply to the heat generating unit. Radiant heater.

8. 8. The radiant heater according to claim 7, The current supply control unit is when the determination unit determines that a human body has come into contact with the heating unit, an amount of current supplied to the heating unit is changed so that the temperature of the heating unit becomes a first temperature that is lower than the set temperature; when the determination unit determines that an object has come into contact with the heating unit, the amount of current supplied to the heating unit is changed so that the temperature of the heating unit becomes a second temperature that is lower than the set temperature and higher than the first temperature. Radiant heater.

9. 8. The radiant heater according to claim 7, the substrate is a flexible substrate, the electrode portion and the heat generating portion are formed on the substrate by a sheet-like conductive material having flexibility; Radiant heater.

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