Electrostatic capacitance sensor system

Abstract

To provide an electrostatic capacitance sensor system capable of determining that a target person is approaching both a first electrode member and a second electrode member.SOLUTION: An electrostatic capacitance sensor system 100 includes: a sensor circuit part 11; a control unit 13; a first electrode member 21 and a second electrode member 22 that are connected to the sensor circuit part 11; and a power input unit 12 that alternately inputs first switching power and second switching power to the second electrode member 22 with reference power input to the first electrode member 21. The control unit 13 determines whether a target person H is approaching both the first electrode member 21 and the second electrode member 22 on the basis of a first electrostatic capacitance C1 of the first electrode member 21 in a state where the reference power and the first switching power are input to the first electrode member 21 and the second electrode member 22, respectively, and a second electrostatic capacitance C2 of the first electrode member 21 in a state where the reference power and the second switching power are input to the first electrode member 21 and the second electrode member 22, respectively.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a capacitive sensor system. [Background technology]

[0002] Conventionally, a capacitance sensor system is known (see, for example, Patent Document 1).

[0003] The aforementioned Patent Document 1 discloses a capacitive touch sensor having two sensor electrodes arranged on one side and the other side of a steering wheel. This capacitive touch sensor is configured to detect the capacitance of the sensor electrode on one side and the capacitance of the sensor electrode on the other side when an ignition switch is operated with one hand of a subject who is away from the steering wheel, and to determine whether the steering wheel is being held with one hand or both hands are away from the steering wheel. This determination is made by utilizing the fact that when the steering wheel is being held with one hand, the difference in capacitance between the sensor electrode on one side and the sensor electrode on the other side is relatively large, and when both hands are away from the steering wheel, the difference in capacitance is relatively small. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-166978 Summary of the Invention [Problem to be solved by the invention]

[0005] Although not explicitly stated in Patent Document 1, there is a need to know when a subject is in close proximity to both of the two electrode members at the same time. The capacitive touch sensor described in Patent Document 1 determines whether the steering wheel is being held, triggered by the operation of the ignition switch with one hand, and therefore cannot determine whether the subject is in close proximity to both of the two electrode members at the same time, i.e., whether the driver is holding the steering wheel with both hands.

[0006] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a capacitance sensor system that can determine when a subject is in proximity to both the first electrode member and the second electrode member at the same time. [Means for solving the problem]

[0007] In order to achieve the above object, a capacitance sensor system in one aspect of the present invention includes a sensor circuit unit that detects a change in capacitance due to the proximity of a subject; a control unit that determines the proximity of a subject based on the capacitance detected by the sensor circuit unit; a first electrode member connected to the sensor circuit unit; a second electrode member connected to the sensor circuit unit and separate from the first electrode member; and a power input unit that inputs a reference power to the first electrode member and, while the reference power is input to the first electrode member, alternately inputs a first switching power and a second switching power different from the first switching power to the second electrode member, and the control unit determines whether the subject is in proximity to both the first electrode member and the second electrode member based on the first capacitance of the first electrode member when the reference power and the first switching power are input to the first electrode member and the second electrode member, respectively, and the second capacitance of the first electrode member when the reference power and the second switching power are input to the first electrode member and the second electrode member, respectively. Here, the above-mentioned "proximity" is a broad concept that includes cases where the subject is in direct contact with the first electrode member and the second electrode member, and cases where the subject approaches the first electrode member and the second electrode member through an insulating layer even if there is no direct contact.

[0008] As described above, a capacitance sensor system according to one aspect of the present invention includes a power input unit that alternately inputs a first switching power and a second switching power different from the first switching power to a second electrode member while a reference power is input to a first electrode member, and a control unit that determines whether a subject is in proximity to both the first electrode member and the second electrode member based on a first capacitance of the first electrode member when the reference power and the first switching power are input to the first electrode member and the second electrode member, respectively, and a second capacitance of the first electrode member when the reference power and the second switching power are input to the first electrode member and the second electrode member, respectively. This allows charges to be stored in both the first electrode member and the second electrode member only when the subject is in proximity to both the first electrode member and the second electrode member. Therefore, only when the subject is close to both the first electrode member and the second electrode member, the input to the first electrode member is set to the reference power and the input to the second electrode member is switched to the first switching power and the second switching power, so that the first capacitance and the second capacitance obtained are different values. In other words, when the subject is close to both the first electrode member and the second electrode member, a detection result that is distinguishable from a case where the subject is close to only one of the first electrode member and the second electrode member or a case where the subject is away from both the first electrode member and the second electrode member can be obtained. Therefore, it is possible to determine that the subject is close to both the first electrode member and the second electrode member at the same time.

[0009] In the aforementioned capacitance sensor system according to the aspect, the first switching power preferably includes a ground voltage value, and the second switching power and the reference power preferably include a reference voltage value that is the same voltage value as each other.

[0010] With this configuration, the first switching power input to the second electrode member can be adjusted to the same voltage value as the body ground of the subject, and the second switching power input to the second electrode member can be adjusted to the reference voltage value input to the first electrode member, thereby making it easy to adjust the voltage values ​​input to the first and second electrode members.

[0011] In the capacitance sensor system according to the above aspect, the control unit preferably determines that the subject is in proximity to both the first electrode member and the second electrode member when the difference obtained by subtracting the second capacitance from the first capacitance is a value equal to or greater than a predetermined difference threshold.

[0012] With this configuration, when a subject is close to both the first electrode member and the second electrode member, where the first capacitance and the second capacitance have different values, the difference between the first capacitance and the second capacitance becomes particularly large. By taking advantage of this, it is possible to easily determine whether the subject is close to or not close to both the first electrode member and the second electrode member simply by comparing the difference with a predetermined difference threshold value.

[0013] In the capacitance sensor system according to the above aspect, preferably, the first electrode member and the second electrode member are provided on one side of the left-right direction of a handle member of a steering mechanism mounted on a vehicle and the other side of the left-right direction of the handle member, respectively, and the control unit determines whether both hands of the subject are in contact with the handle member.

[0014] With this configuration, it is possible to easily determine whether the subject is holding the handle member of the steering mechanism with both hands.

[0015] In the capacitance sensor system according to the above aspect, the following configuration is also possible.

[0016] (Additional note 1) In the above capacitance sensor system, the power input unit is preferably configured to alternately switch between the first switching power and the second switching power input to the second electrode member at predetermined short intervals, and the control unit continuously and repeatedly determines whether the subject is in proximity to both the first electrode member and the second electrode member based on the first capacitance and the second capacitance.

[0017] With this configuration, the first capacitance and the second capacitance can be acquired at relatively close times, thereby reducing the impact of disturbances such as temperature changes on the detection results between the acquisition of both the first capacitance and the second capacitance.

[0018] (Additional note 2) In a configuration in which the first electrode member and the second electrode member are provided on a handle member of a steering mechanism mounted on a vehicle, the control unit preferably determines whether or not both hands of the subject are in contact with the handle member when the vehicle is being driven automatically.

[0019] With this configuration, when the vehicle is being driven automatically, various controls can be performed, such as issuing a predetermined warning or switching to a predetermined driving mode, based on the fact that both hands of the subject are not in contact with the steering wheel member. [Effects of the Invention]

[0020] According to the present invention, as described above, it is possible to provide a capacitance sensor system that can determine whether a subject is in proximity to both the first electrode member and the second electrode member at the same time. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a block diagram showing a configuration of a capacitance sensor system mounted on a vehicle according to an embodiment; [Figure 2] 4 is a schematic diagram showing the arrangement of a sensor main body, a first electrode member, and a second electrode member in a handle member according to one embodiment. FIG. [Figure 3] 10 is a diagram for explaining a circuit model formed by a subject holding a handle member, a first electrode member, and a second electrode member. FIG. [Figure 4] 10A and 10B are diagrams for explaining a specific example of the first capacitance and the second capacitance when the handle member is held with both hands and when it is not held with both hands. [Figure 5] 10 is a flowchart illustrating a control process for determining whether the capacitance sensor system is holding with both hands or not, performed by a control unit of the capacitance sensor system. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0023] A capacitance sensor system 100 according to this embodiment will be described with reference to FIGS.

[0024] (Vehicle configuration) As shown in FIGS. 1 and 2, the capacitance sensor system 100 is mounted on a vehicle 101. The vehicle 101 is mounted with a steering mechanism 30. The steering mechanism 30 is a steering device for changing the traveling direction of the vehicle 101. The steering mechanism 30 includes a handle member 31 held by the subject H. That is, the handle member 31 is a steering wheel held by the subject H who is the driver of the vehicle 101. The steering mechanism 30 is an attachment target to which a sensor main body 10, which will be described later, is attached. In this embodiment, the capacitance sensor system 100 (control unit 13) determines whether the subject H is holding the handle member 31 with both hands.

[0025] The vehicle 101 also includes an ECU 40 (Electronic Control Unit). The ECU 40 is configured to control the operation of each part of the vehicle 101. The ECU 40 is a computer including, for example, an arithmetic unit such as a CPU (Central Processing Unit) and a storage device having a nonvolatile memory such as a flash memory, and is a higher-level control device for the capacitance sensor system 100. A detection signal of the capacitance sensor system 100 is acquired by the ECU 40. As an example, the ECU 40 performs predetermined control related to autonomous driving based on the detection signal of the capacitance sensor system 100. That is, the ECU 40 performs predetermined control related to autonomous driving based on a determination result of whether or not the subject H is holding the steering wheel member 31 with both hands.

[0026] (Capacitive sensor system configuration) The capacitance sensor system 100 comprises a sensor main body 10, a sensor circuit 11, a power input section 12, a control section 13, a first electrode member 21, and a second electrode member 22 separate from the first electrode member 21.

[0027] The sensor main body 10 is disposed on a handle member 31. Specifically, the handle member 31 has an annular portion 31a that is held by the subject H, and an inner peripheral portion 31b that is located on the inner peripheral side of the annular portion 31a. The sensor main body 10 is disposed inside the inner peripheral portion 31b. The sensor main body 10 houses a sensor circuit portion 11, a power input portion 12, and a control portion 13 therein. The sensor circuit portion 11 is also provided with connection terminals for connecting to the ECU 40, the first electrode member 21, and the second electrode member 22 via wiring.

[0028] The sensor circuit unit 11 and the power input unit 12 are both connected to both the first electrode member 21 and the second electrode member 22. The first electrode member 21 and the second electrode member 22 are respectively provided on one lateral side and the other lateral side of a handle member 31 of a steering mechanism 30 mounted on a vehicle 101. Specifically, the first electrode member 21 is disposed to the left of an annular portion 31a of the handle member 31. The first electrode member 21 has an arc shape extending along the annular portion 31a and is disposed over substantially the entire leftward area of ​​the annular portion 31a. The second electrode member 22 is disposed to the right of the annular portion 31a of the handle member 31. The second electrode member 22 has an arc shape extending along the annular portion 31a and is disposed over substantially the entire rightward area of ​​the annular portion 31a.

[0029] The power input unit 12 inputs a predetermined power (voltage) to the first electrode member 21 and the second electrode member 22. In this state, the sensor circuit unit 11 detects the capacitance that changes as the subject H approaches the first electrode member 21 and the second electrode member 22. The control unit 13 determines the approach of the subject H based on the capacitance detected by the sensor circuit unit 11. That is, the power input unit 12, the sensor circuit unit 11, the first electrode member 21, and the second electrode member 22 form a capacitance sensor. Then, based on the capacitance detected by the power input unit 12, the sensor circuit unit 11, the first electrode member 21, and the second electrode member 22, the control unit 13 determines whether the handle member 31 is being held with both hands.

[0030] The capacitance sensor system 100 includes only one capacitance sensor configured with the power input unit 12, the sensor circuit unit 11, the first electrode member 21, and the second electrode member 22. In other words, the capacitance sensor system 100 does not include a capacitance sensor that is disposed to the left of the handle member 31 and detects that the handle member 31 is being held by the left hand LH, and a capacitance sensor that is disposed to the right of the handle member 31 and detects that the handle member 31 is being held by the right hand RH, separately.

[0031] As an example, the sensor circuit unit 11 includes an IC (Integrated Circuit). The power input unit 12 is a circuit for applying a predetermined voltage to the first electrode member 21 and the second electrode member 22. The control unit 13 also includes a microcomputer including a calculation device such as a CPU and a storage device such as a nonvolatile memory.

[0032] The power input unit 12 is configured to input a reference power to the first electrode member 21, and to alternately input a first switching power and a second switching power different from the first switching power to the second electrode member 22 while the reference power is input to the first electrode member 21. The first switching power includes a ground voltage value VG (=0 [V]). The second switching power and the reference power both include a reference voltage value Vref, which is the same voltage value.

[0033] The power input unit 12 is configured to alternately switch between a first switching power (ground voltage value VG=0 [V]) and a second switching power (reference voltage value Vref) input to the second electrode member 22 at predetermined short time intervals. The predetermined short time interval is at least a time interval shorter than 0.1 μsec. More preferably, the predetermined short time interval is a time interval shorter than 1000 μsec. As a specific example, the predetermined short time interval is 200 μsec.

[0034] (Configuration of control unit) The control unit 13 determines whether or not the subject H is in proximity to both the first electrode member 21 and the second electrode member 22, based on the first capacitance C1 and the second capacitance C2 of the first electrode member 21. In short, the control unit 13 determines whether or not the subject H is holding the handle member 31 with both hands, based on the first capacitance C1 and the second capacitance C2 that vary due to the proximity of one hand, the left hand LH, of the subject H, and the other hand, the right hand RH.

[0035] The "first capacitance C1" is the capacitance of the first electrode member 21 in a state where a reference power (reference voltage value Vref) and a first switching power (ground voltage value VG=0 [V]) are input to the first electrode member 21 and the second electrode member 22, respectively. The "second capacitance C2" is the capacitance of the first electrode member 21 in a state where a reference power (reference voltage value Vref) and a second switching power (reference voltage value Vref) are input to the first electrode member 21 and the second electrode member 22, respectively. The "proximity" is a broad concept that includes a case where the subject H is in direct contact with the first electrode member 21 and the second electrode member 22, and a case where the subject H approaches the first electrode member 21 and the second electrode member 22 through an insulating layer even if there is no direct contact.

[0036] In detail, the control unit 13 subtracts the second capacitance C2 from the first capacitance C1 to obtain a difference ΔC obtained by subtracting the second capacitance C2 from the first capacitance C1. Then, when the difference ΔC obtained by subtracting the second capacitance C2 from the first capacitance C1 is equal to or greater than a predetermined difference threshold T, the control unit 13 determines that the subject H is in proximity to both the first electrode member 21 and the second electrode member 22. In other words, when the difference ΔC is equal to or greater than the predetermined difference threshold T, the control unit 13 determines that the subject H is holding the handle member 31 with both his or her left hand LH and right hand RH.

[0037] Furthermore, when the difference ΔC obtained by subtracting the second capacitance C2 from the first capacitance C1 is a value less than a predetermined difference threshold T, the control unit 13 determines that the subject H is not in proximity to both the first electrode member 21 and the second electrode member 22. In other words, when the value is less than the predetermined difference threshold T, the control unit 13 determines that the subject H is not holding the handle member 31 with both the left hand LH and the right hand RH.

[0038] The control unit 13 performs at least the above-described control of determining whether or not both hands of the subject H are in contact with the steering wheel member 31 during automatic driving of the vehicle 101. As an example, when the vehicle 101 is automatically driven, if a state in which at least one hand of the subject H is not holding the steering wheel member 31 continues for a predetermined time or longer, the control unit 13 transmits a signal to the ECU 40 to issue a predetermined warning to the subject H.

[0039] Each time the first switching power (ground voltage value VG=0 [V]) and the second switching power (reference voltage value Vref) are alternately switched at the predetermined short time intervals described above, the control unit 13 continuously and repeatedly determines whether or not the subject H is in proximity to both the first electrode member 21 and the second electrode member 22, based on the first capacitance C1 and the second capacitance C2.

[0040] (Circuit model formed by the subject, the first electrode member, and the second electrode member) Referring to FIG. 3, a circuit model formed by the subject H holding the handle member 31, the first electrode member 21 and the second electrode member 22 will be described.

[0041] When the subject H holds the handle member 31 with his / her left hand LH, that is, when the left hand LH is brought close to the first electrode member 21, a pseudo capacitor CN1 is formed by the first electrode member 21 and the left hand LH. The capacitance of the pseudo capacitor CN1 formed by the first electrode member 21 and the left hand LH is defined as CL.

[0042] Furthermore, when the subject H holds the handle member 31 with his / her right hand RH, that is, when the right hand RH is brought close to the second electrode member 22, a pseudo capacitor CN2 is formed by the second electrode member 22 and the right hand RH. The capacitance of the pseudo capacitor CN2 formed by the second electrode member 22 and the right hand RH is defined as CR.

[0043] In addition, a pseudo capacitor CN3 is formed in the subject H itself between the left hand LH and right hand RH and the body ground (VB=0[V]) of the subject H (human body). The capacitance of the pseudo capacitor CN3 alone formed in the subject H itself is defined as CB.

[0044] In a state where the reference voltage value Vref is input to the first electrode member 21 and a first switching power (ground voltage value VG=0 [V]) is input to the second electrode member 22, the overall combined capacitance of the circuit model constituting the pseudo capacitor CN1 as viewed from the first electrode member 21 side is the first capacitance C1 (see FIG. 4). In short, this first capacitance C1 is the actual, not pseudo, capacitance of the first electrode member 21 in a state where the reference voltage value Vref is input to the first electrode member 21 and the first switching power (ground voltage value VG=0 [V]) is input to the second electrode member 22. In this case, the charge stored between the first electrode member 21 and the subject H is "first capacitance C1 × reference voltage value Vref."

[0045] Furthermore, in a state where the reference voltage value Vref is input to the first electrode member 21 and the second switching power (reference voltage value Vref) is input to the second electrode member 22, the overall combined capacitance of the circuit model constituting the pseudo capacitor CN1 as viewed from the first electrode member 21 side becomes the second capacitance C2 (see FIG. 4). In short, this second capacitance C2 is the actual, not pseudo, capacitance of the first electrode member 21 in a state where the reference voltage value Vref is input to the first electrode member 21 and the second switching power (reference voltage value Vref) is input to the second electrode member 22. In this case, the charge stored between the first electrode member 21 and the subject H becomes "the second capacitance C2 × the reference voltage value Vref."

[0046] (Specific examples of the first capacitance and the second capacitance when the handle member is held with both hands and when it is not held with both hands) 3 and 4, a specific example of the first capacitance C1 and the second capacitance C2 when the handle member 31 is held with both hands and when it is not held with both hands will be described.

[0047] Below, we will explain the case where the relationship between the subject H and the handle member 31 changes sequentially through five states, namely, non-holding state, left hand holding state, both hands holding state, right hand holding state, and non-holding state, as shown in Figure 4.

[0048] In the circuit shown in FIG. 4, the capacitance of each capacitor CN1, CN2, and CN3 (the amount of charge stored in each capacitor CN1, CN2, and CN3) is indicated by the size of the arrow passing through each capacitor CN1, CN2, and CN3. That is, if the capacitance of the capacitor is large, the arrow is large, and if the capacitance of the capacitor is small, the arrow is small. The arrows come in three sizes: large, medium, and small. Furthermore, the first electrode member 21 and the second electrode member 22 that are not close to the hand of subject H are described as "open."

[0049] First, in the non-holding state shown in FIG. 4A, both the first electrode member 21 and the second electrode member 22 are "open." In this case, the first capacitance C1 and the second capacitance C2 of the first electrode member 21 are both (substantially) zero. Therefore, the difference ΔC obtained by subtracting the second capacitance C2 from the first capacitance C1 is (substantially) zero. Therefore, in the non-holding state, the difference ΔC is less than a predetermined difference threshold T.

[0050] Next, when the state changes to the left-hand holding state shown in FIG. 4(B), only the second electrode member 22 becomes "open." In this case, the first capacitance C1 and the second capacitance C2 of the first electrode member 21 are both C1 = C2 = (CL × CB) / (CL + CB). In this case, the pseudo capacitors CN1 and CN3 are in a series relationship. Therefore, the difference ΔC obtained by subtracting the second capacitance C2 from the first capacitance C1 is (almost) zero. Therefore, in the left-hand holding state, the difference ΔC is less than a predetermined difference threshold T.

[0051] Next, when the state changes to the two-handed holding state shown in FIG. 4(C), when the first switching power (ground voltage value VG=0 [V]) is input to the second electrode member 22, the voltage value (potential) of the first electrode member 21 becomes the largest with respect to the two ground voltages on the second electrode member 22 side and the body ground side. In this case, the pseudo capacitors CN2 and CN3 are connected in parallel, and the pseudo capacitors CN2 and CN3 are connected in series with the pseudo capacitor CN1. Therefore, the first capacitance C1 of the first electrode member 21 is obtained by Equation 1: C1=[CL×(CR+CB)] / [CL+(CR+CB)]=[(CL×CR) / (CL+CR+CB)]+[(CL×CB) / (CL+CR+CB)].

[0052] In this way, the first capacitance C1 of the first electrode member 21 in the both-hand held state increases from the first capacitance C1 of the first electrode member 21 in the previous left-hand held state.

[0053] 4(C), when the second switching power (reference voltage Vref) is input to the second electrode member 22, the voltage values ​​of the first electrode member 21 and the second electrode member 22 both become the reference voltage Vref. In this case, the pseudo capacitors CN1 and CN2 are connected in parallel, and the pseudo capacitors CN1 and CN2 are connected in series with the pseudo capacitor CN3. Therefore, the second capacitance C2 of the first electrode member 21 is obtained by Equation 2, C2=[(CL+CR)×CB] / [(CL+CR)+CB]×[CL / (CL+CR)]=(CL×CB) / (CL+CR+CB).

[0054] In this way, the second capacitance C2 of the first electrode member 21 in the both-hand held state decreases from the first capacitance C1 of the first electrode member 21 in the previous left-hand held state.

[0055] Naturally, the first capacitance C1 of the first electrode member 21 in the both-hands-held state is larger than the second capacitance C2 of the first electrode member 21 in the both-hands-held state. Therefore, the difference ΔC obtained by subtracting the second capacitance C2 from the first capacitance C1 becomes a relatively large value, and the difference ΔC in the both-hands-held state becomes equal to or greater than a predetermined difference threshold T.

[0056] Next, when the state changes to the right-hand holding state shown in FIG. 4(D), only the first electrode member 21 becomes "open." Therefore, the first capacitance C1 and the second capacitance C2 of the first electrode member 21 are both (substantially) zero. Therefore, the difference ΔC obtained by subtracting the second capacitance C2 from the first capacitance C1 is (substantially) zero. Therefore, in the right-hand holding state, the difference ΔC is less than the predetermined difference threshold T.

[0057] Next, the case where the state changes again to the non-holding state shown in FIG. 4(E) is the same as that described with reference to FIG. 4(A), and therefore the description will be omitted.

[0058] As described above, the first capacitance C1 and the second capacitance C2 have different values ​​when the subject H is close to both the first electrode member 21 and the second electrode member 22, and have approximately the same value when the subject H is not holding the electrodes with both hands. The "not holding the electrodes with both hands" state includes a separated state in which the subject H is not close to either the first electrode member 21 or the second electrode member 22, and a state in which the subject H is close to only one of the first electrode member 21 and the second electrode member 22.

[0059] (Control process by the control unit to determine whether the device is holding something with both hands or not) Referring to FIG. 5, a flowchart of the control process of determining whether the device is held with both hands or not by the control unit 13 will be described.

[0060] First, in step S1, a reference voltage value Vref is input to the first electrode member 21. Furthermore, a first switching power (ground voltage value VG=0 [V]) is input to the second electrode member 22. Therefore, as a result of step S1, the voltage value (potential) of the first electrode member 21 becomes greater than the voltage value (potential) of the second electrode member 22.

[0061] Then, in step S2, the first capacitance C1 is acquired while the reference voltage value Vref is input to the first electrode member 21 and the first switching power (ground voltage value VG=0 [V]) is input to the second electrode member 22.

[0062] Then, in step S3, it is determined whether a predetermined time interval has elapsed. In other words, the process waits until the predetermined time interval has elapsed. If the predetermined time interval has elapsed, the process proceeds to step S4. As an example, the predetermined time interval is 200 μsec, as described above.

[0063] Then, in step S4, the input to the second electrode member 22 is switched from the first switching power (ground voltage value VG=0 [V]) to the second switching power (reference voltage value Vref). Therefore, as a result of step S4, the voltage value (potential) of the first electrode member 21 and the voltage value (potential) of the second electrode member 22 become equal to each other.

[0064] Then, in step S5, the reference voltage value Vref is input to the first electrode member 21, and the second switching power (reference voltage value Vref) is input to the second electrode member 22, and the second capacitance C2 is acquired.

[0065] Then, in step S6, it is determined whether the difference ΔC obtained by subtracting the second capacitance C2 from the first capacitance C1 is equal to or greater than a predetermined difference threshold T. If the difference ΔC is equal to or greater than the predetermined difference threshold T, the process proceeds to step S7, and if the difference ΔC is less than the predetermined difference threshold T, the process proceeds to step S8.

[0066] Then, in step S7, it is determined that the handle member 31 is being held with both hands, that is, it is determined that it is in the state shown in Fig. 4(C), and then the process proceeds to step S9.

[0067] In step S8, it is determined that the handle member 31 is not held with both hands. That is, it is determined that the handle member 31 is in one of the states shown in Figures 4(A), (B), (D), and (E), namely, the unheld state, the left-hand held state, and the right-hand held state. Then, the process proceeds to step S9.

[0068] Then, in step S9, it is determined whether or not a predetermined time interval has elapsed. In other words, the process is in a standby state until the predetermined time interval has elapsed. If the predetermined time interval has elapsed, the process proceeds to step S10. Note that, as an example, the predetermined time interval is 200 μsec as described above.

[0069] Then, in step S10, the input to the second electrode member 22 is switched from the second switching power (reference voltage value Vref) to the first switching power (ground voltage value VG=0 [V]). Therefore, as a result of step S10, the voltage value (potential) of the first electrode member 21 becomes greater than the voltage value (potential) of the second electrode member 22. Thereafter, the process returns to step S2, and steps S2 to S10 are repeated again.

[0070] (Effects of this embodiment) In this embodiment, the following effects can be obtained.

[0071] As described above, this embodiment includes the power input unit 12 that alternately inputs a first switching power and a second switching power different from the first switching power to the second electrode member 22 while a reference power is input to the first electrode member 21, and the control unit 13 that determines whether the subject H is in proximity to both the first electrode member 21 and the second electrode member 22 based on the first capacitance C1 of the first electrode member 21 when the reference power and the first switching power are input to the first electrode member 21 and the second electrode member 22, respectively, and the second capacitance C2 of the first electrode member 21 when the reference power and the second switching power are input to the first electrode member 21 and the second electrode member 22, respectively. This makes it possible to store electric charge in both the first electrode member 21 and the second electrode member 22 only when the subject H is in proximity to both the first electrode member 21 and the second electrode member 22. Therefore, only when the subject H is in proximity to both the first electrode member 21 and the second electrode member 22, the first capacitance C1 and the second capacitance C2 obtained by setting the input of the first electrode member 21 to the reference power and switching the input of the second electrode member 22 to the first switching power and the second switching power can be made to have mutually different values. In other words, when the subject H is in proximity to both the first electrode member 21 and the second electrode member 22, a detection result that is distinguishable from a case in which the subject H is in proximity to only one of the first electrode member 21 and the second electrode member 22 and a case in which the subject H is away from both the first electrode member 21 and the second electrode member 22 can be obtained. Therefore, it is possible to determine that the subject H is in proximity to both the first electrode member 21 and the second electrode member 22 at the same time.

[0072] In the present embodiment, as described above, the first switching power includes the ground voltage value VG, and the second switching power and the reference power include the reference voltage value Vref, which are the same voltage value. This makes it possible to adjust the first switching power input to the second electrode member 22 to the same voltage value as the body ground of the subject H, and to adjust the second switching power input to the second electrode member 22 to the reference voltage value Vref input to the first electrode member 21. Therefore, the voltage values ​​input to the first electrode member 21 and the second electrode member 22 can be easily adjusted.

[0073] In the present embodiment, as described above, when the difference ΔC obtained by subtracting the second capacitance C2 from the first capacitance C1 is equal to or greater than the predetermined difference threshold T, the control unit 13 determines that the subject H is in proximity to both the first electrode member 21 and the second electrode member 22. As a result, when the subject H is in proximity to both the first electrode member 21 and the second electrode member 22, in which the first capacitance C1 and the second capacitance C2 have different values, the difference ΔC between the first capacitance C1 and the second capacitance C2 becomes particularly large. By utilizing this, it is possible to easily determine that the subject H is in proximity to both the first electrode member 21 and the second electrode member 22 or is not in proximity to both the first electrode member 21 and the second electrode member 22 simply by comparing the magnitude with the predetermined difference threshold T.

[0074] In this embodiment, as described above, the first electrode member 21 and the second electrode member 22 are provided on one side in the left-right direction and the other side in the left-right direction of the handle member 31 of the steering mechanism 30 mounted on the vehicle 101, respectively, and the control unit 13 determines whether or not both hands of the subject H are in contact with the handle member 31. This makes it possible to easily determine whether the subject H is holding the handle member 31 of the steering mechanism 30 with both hands.

[0075] In this embodiment, as described above, the power input unit 12 is configured to alternately switch between the first switching power and the second switching power to be input to the second electrode member 22 at predetermined short intervals, and the control unit 13 continuously and repeatedly determines whether or not the subject H is in proximity to both the first electrode member 21 and the second electrode member 22, based on the first capacitance C1 and the second capacitance C2. This allows the first capacitance C1 and the second capacitance C2 to be acquired relatively close to each other, thereby reducing the influence of disturbances such as temperature changes on the detection results while both the first capacitance C1 and the second capacitance C2 are acquired.

[0076] In this embodiment, as described above, the control unit 13 determines whether or not both hands of the subject H are in contact with the steering wheel member 31 during automatic driving of the vehicle 101. This makes it possible to perform various controls, such as issuing a predetermined warning or switching to a predetermined driving mode, based on the fact that both hands of the subject H are not in contact with the steering wheel member 31 during automatic driving of the vehicle 101.

[0077] [Variations] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than the above description of the embodiments, and further includes all modifications (variations) within the meaning and scope of the claims.

[0078] For example, in the above embodiment, the first electrode member is disposed on the left side of the handle member and the second electrode member is disposed on the right side of the handle member, but the present invention is not limited to this. In the present invention, the first electrode member may be disposed on the right side of the handle member and the second electrode member may be disposed on the left side of the handle member.

[0079] In the above embodiment, both the first electrode member and the second electrode member are disposed on the handle member, but the present invention is not limited to this. In the present invention, one of the first electrode member and the second electrode member may be disposed on the handle member, and the other may be disposed on a seat on which the subject sits. Furthermore, instead of detecting the proximity of the subject's upper limbs (hands) to the handle member, the capacitance sensor system may also be configured to detect the proximity of a predetermined structure such as the subject's lower limbs (feet).

[0080] In the above embodiment, the capacitance sensor system is provided in a vehicle, but the present invention is not limited to this. For example, the capacitance sensor system may be provided in other vehicles such as an airplane or a ship, or may be provided in a control panel of a predetermined piece of equipment that is not a vehicle, and used to determine whether the equipment is running or stopped based on whether two points are in contact at the same time.

[0081] In the above embodiment, the capacitance sensor system is configured to be capable of determining whether or not the vehicle handlebars are being held with both hands, but the present invention is not limited to this. In the present invention, the capacitance sensor system may be configured to be capable of determining whether or not the vehicle handlebars are being held with both hands, as well as whether or not the vehicle handlebars are being held with one hand.

[0082] In the above embodiment, the first switching power is set to the ground voltage, but the present invention is not limited to this. In the present invention, the first switching power may be set to a voltage value different from the ground voltage. In this case, the first switching power is set to a voltage value different from the second switching power.

[0083] In the above embodiment, the second switching power is set to a reference voltage value, but the present invention is not limited to this. In the present invention, the second switching power may be set to a voltage value different from the reference voltage value. In this case, the second switching power is set to a voltage value different from the first switching power.

[0084] In the above embodiment, an example is shown in which the first switching power and the second switching power are switched and input only to the second electrode member, but the present invention is not limited to this. In the present invention, not only the reference power but also two different powers may be switched and input to the first electrode member as well as the second electrode member.

[0085] In the above embodiment, an example was shown in which voltages (reference voltage value, ground voltage value) were input to the first electrode member and the second electrode member, but the present invention is not limited to this. In the present invention, other parameters such as current and charge may be input to the first electrode member and the second electrode member.

[0086] In the above embodiment, an example was shown in which the difference obtained by subtracting the second capacitance from the first capacitance was compared with a predetermined difference threshold to determine whether or not the subject is in proximity to both the first electrode member and the second electrode member, but the present invention is not limited to this. For example, in the present invention, the rate of change (differential value) of the difference obtained by subtracting the second capacitance from the first capacitance may be compared with a predetermined threshold to determine whether or not the subject is in proximity to both the first electrode member and the second electrode member.

[0087] In the above embodiment, the predetermined short time interval for alternately switching the first switching power and the second switching power input to the second electrode member is set to 200 μsec, but the present invention is not limited to this. In the present invention, the predetermined short time interval may be set to a length different from 200 μsec.

[0088] In the above embodiment, the first electrode member and the second electrode member are formed in an arc shape along the annular handle member, but the present invention is not limited to this. In the present invention, the first electrode member and the second electrode member may be formed in a linear shape, an L-shape, or the like.

[0089] Furthermore, in the above embodiment, for convenience of explanation, the processing operation of the control unit is described using a flow-driven flowchart in which processing is performed sequentially according to a processing flow, but the present invention is not limited to this. In the present invention, the processing operation of the control unit may be performed by event-driven processing in which processing is performed on an event-by-event basis. In this case, the processing may be performed completely event-driven, or may be performed in a combination of event-driven and flow-driven. For example, after performing processing to obtain the second capacitance, processing to obtain the first capacitance may be performed, and the difference may be obtained by subtracting the second capacitance from the first capacitance. [Explanation of symbols]

[0090] 11: sensor circuit unit, 12: power input unit, 13: control unit, 21: first electrode member, 22: second electrode member, 30: steering mechanism, 31: handle member, 100: capacitance sensor system, 101: vehicle, C1: first capacitance, C2: second capacitance, H: subject, LH: left hand (one hand), RH: right hand (other hand), T: predetermined difference threshold, Vref: reference voltage value (reference power, second switching power), VG: ground voltage value (first switching power)

Claims

1. a sensor circuit unit that detects a change in capacitance due to the proximity of a target person; a control unit that determines the proximity of the target person based on the capacitance detected by the sensor circuit unit; a first electrode member connected to the sensor circuit unit; a second electrode member connected to the sensor circuit unit and separate from the first electrode member; a power input unit that inputs a reference power to the first electrode member, and that, while the reference power is being input to the first electrode member, alternately switches between inputting a first switching power and a second switching power different from the first switching power to the second electrode member, The control unit determines whether the subject is in proximity to both the first electrode member and the second electrode member based on a first capacitance of the first electrode member when the reference power and the first switching power are input to the first electrode member and the second electrode member, respectively, and a second capacitance of the first electrode member when the reference power and the second switching power are input to the first electrode member and the second electrode member, respectively.

2. the first switching power includes a ground voltage value; The capacitive sensor system according to claim 1 , wherein the second switching power and the reference power include a reference voltage value that is the same voltage value as each other.

3. The control unit 2. The capacitance sensor system of claim 1, wherein when a difference obtained by subtracting the second capacitance from the first capacitance is equal to or greater than a predetermined difference threshold, it is determined that the subject is in proximity to both the first electrode member and the second electrode member.

4. the first electrode member and the second electrode member are provided on one side in a left-right direction of a handle member of a steering mechanism mounted on a vehicle and on the other side in a left-right direction of the handle member, respectively; The capacitance sensor system according to claim 1 , wherein the control unit determines whether or not both hands of the subject are in contact with the handle member.

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