JP2021048448A - Operation detection device - Google Patents

Abstract

To suppress erroneous detection.SOLUTION: In an operation detection device 10, a sensor electrode 16 facing a shield electrode 18 is connected to a control unit 20 via a wiring 30. Further, the control unit 20 side of the wiring 30 is connected to the shield electrode 18 via a buffer unit 32, and the shield electrode 18 side of the buffer unit 32 can be grounded via a switch unit 24. The operation detection device 10 detects the presence or absence of disconnection of the wiring 30 by setting the shield electrode 18 to a ground state by the switch unit 24. As a result, it is possible to detect an operation on the sensor electrode 16 and detect the presence or absence of disconnection of the wiring 30, and thus, it is possible to suppress erroneous detection caused by disconnection of the wiring 30.SELECTED DRAWING: Figure 1

Description

The present invention relates to a capacitance type operation detection device.

The input device of Patent Document 1 is provided with a sensor electrode in the switch unit and a cancel electrode for reducing the parasitic capacitance between the sensor electrode and the reference point, and the operation on the sensor electrode is detected by the detection unit. To. Further, in the input device, the control unit applies a drive signal to the sensor electrode and a signal having the same waveform as the drive signal is applied to the cancel electrode, and the detection unit performs an input operation from the change in the capacitance of the sensor electrode. Detects whether or not it has been done.

JP-A-2018-037348

By the way, the sensor electrode, the detection unit, and the control unit are connected by electrical wiring. For this reason, erroneous detection occurs due to poor energization (contact failure) such as disconnection in the electrical wiring.

The present invention has been made in view of the above facts, and an object of the present invention is to provide an operation detection device capable of suppressing erroneous detection.

The operation detection device of the first aspect of the present invention is opposite to the sensor electrode whose capacitance changes with the operator when the operator is brought close to the operator and the proximity side of the sensor electrode to the operator. An electrode unit having a counter electrode facing the side and a detection unit connected to the sensor electrode and detecting the proximity of the operator to the sensor electrode and the connection state with the sensor electrode by detecting the capacitance. When the detection unit detects the proximity of the operator to the sensor electrode, the counter electrode is connected to the detection unit so that the potential becomes the same as that of the sensor electrode, and the detection unit is connected to the detection unit. When detecting the connection state with the sensor electrode, the connection portion with the counter electrode in the ground state is included.

In the operation detection device of the second aspect, in the first aspect, the connection portion is controlled so that the counter electrode has a potential similar to that of the sensor electrode, and the counter electrode is grounded in the first state. A switching means for switching to the second state is provided, and the detection unit includes a control means for controlling the switching means.

In the operation detection device of the first aspect, the sensor electrode whose capacitance changes with the operator when the operator is brought close to the electrode portion, and the side of the sensor electrode opposite to the close side of the operator. A counter electrode is provided so as to face the surface. The detection unit is connected to the sensor electrode, and the detection unit detects the capacitance.

Here, when the detection unit detects the proximity of the operator to the sensor electrode, the connection unit connects the counter electrode to the detection unit so that the potential becomes the same as that of the sensor electrode. Further, when the detection unit detects the connection state between the detection unit and the sensor electrode, the connection unit puts the counter electrode in the grounded state.

When the detection unit detects the proximity of the operator to the sensor electrode, if the sensor electrode and the counter electrode have the same potential, the capacitance between the sensor electrode and the counter electrode decreases. Further, when the detection unit detects the connection state between the detection unit and the sensor electrode, the capacitance between the sensor electrode and the counter electrode is increased by putting the counter electrode in the grounded state.

Therefore, when detecting the connection state between the detection unit and the sensor electrode, the detection unit may have a disconnection or the like in the electrical wiring connecting the detection unit and the sensor electrode, or may not have a disconnection. The detected capacitance is very different. As a result, the proximity of the operator to the sensor electrode and the connection state with the sensor electrode can be accurately detected, and erroneous detection by the detection unit can be suppressed.

In the operation detection device of the second aspect, a switching means is provided in the connection portion, and the switching means has a first state in which the counter electrode has the same potential as the sensor electrode and a second state in which the counter electrode is grounded. Switch to. Further, the detection unit is provided with a control means for controlling the switching means.

As a result, the control means controls the switching means, so that the detection unit can appropriately detect the proximity of the operator to the sensor electrode and the connection state with the sensor electrode.

It is a schematic block diagram of the operation detection apparatus which concerns on this embodiment. It is the schematic which shows the capacitance around a sensor electrode in an electrode part. It is a schematic diagram which shows the capacitance around a sensor electrode at the time of operation detection, (A) shows the proximity state, and (B) shows the non-proximity state. It is a schematic diagram which shows the capacitance around a sensor electrode in a non-disconnection state at the time of disconnection detection, (A) shows a proximity state, and (B) shows a non-proximity state. It is a schematic diagram which shows the capacitance around a sensor electrode in the disconnection state at the time of disconnection detection, (A) shows the proximity state, and (B) shows the non-proximity state.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a schematic configuration diagram of the operation detection device 10 according to the present embodiment.
As shown in FIG. 1, the operation detection device 10 includes an electrode unit 12 and a controller 14. The operation detection device 10 is of a capacitance type (self-capacitance type), and a sensor electrode 16 and a shield electrode 18 as a counter electrode are used for the electrode portion 12.

The sensor electrode 16 and the shield electrode 18 are each in the form of a sheet, and the sensor electrode 16 and the shield electrode 18 are overlapped with each other via an insulating sheet-like film (dielectric, not shown). As a result, the electrode portion 12 is formed in a sheet shape in which the sensor electrode 16 and the shield electrode 18 are arranged in layers.

Further, the sensor electrode 16 and the shield electrode 18 have the same area of surfaces facing each other, or the shield electrode 18 is wider (larger) than the sensor electrode 16. As a result, in the electrode portion 12, the shield electrode 18 side of the sensor electrode 16 is covered with the shield electrode 18. Therefore, in the electrode portion 12, the capacitance generated in the sensor electrode 16 is increased when a person (a part of the human body, for example, a hand or a finger) approaches the surface of the sensor electrode 16 opposite to the shield electrode 18. Change (increase).

The controller 14 is formed with a detection unit, a control unit 20 as a control means, and switch units 22 and 24, and the controller 14 operates by being supplied with electric power from a power source (not shown). Two terminals (contacts) 22A and 22B are formed on the primary side of the switch unit 22, and one terminal (contact) 22C is formed on the secondary side. It is switched between terminals 22A and 22B.

The terminal 22A of the switch unit 22 is on the power feeding side, a constant current source (constant current circuit) 26 is connected to the terminal 22A, and a predetermined current is supplied from the constant current source 26. Further, the switch unit 22 has a terminal 22B as a detection side, and is connected to the terminal 22B on the input side of an ADC (Analog-Digital Converter: AD converter) 28. Further, the output side of the ADC 28 is connected to the control unit 20.

One end of the wiring (electrical wiring) 30 is connected to the terminal 22C of the switch unit 22. The other end of the wiring 30 is connected to the sensor electrode 16 of the electrode portion 12. Therefore, when the terminal 22C is connected to the terminal 22A on the power feeding side, the constant current source 26 is connected to the sensor electrode 16 and the power is supplied to the sensor electrode 16. At the sensor electrode 16, a voltage corresponding to the capacitance is generated by supplying power.

Further, by connecting the terminal 22C to the terminal 22B on the detection side, the sensor electrode 16 is connected to the ADC 28, and the detection signal (voltage signal) corresponding to the voltage (capacitance) generated in the sensor electrode 16 is output to the control unit. It is input to 20. The detection signal input to the control unit 20 has a magnitude (voltage level) corresponding to the electric charge (capacitance) accumulated in the sensor electrode 16. The control unit 20 compares the input detection signal (which may be the capacitance obtained from the detection signal) with a preset threshold value, and attaches the sensor electrode 16 to the operator (operator's hand or finger). Detects whether or not they are in close proximity.

On the other hand, the operation detection device 10 is provided with a buffer unit 32, and the buffer unit 32 and the switch unit 24 form a connection unit 34 as a connection means. An operational amplifier OP is used in the buffer unit 32, and the operational amplifier OP is operated by electric power supplied from the control unit 20 of the controller 14 in which a voltage follower is configured with a shutdown function. The output side of the buffer unit 32 (op amp OP) has high impedance. The input side of the buffer unit 32 is connected to the switch unit 22 (terminal 22C) side of the wiring 30, and the output side of the buffer unit 32 is connected to the shield electrode 18 of the electrode unit 12. As a result, the buffer unit 32 can operate so that the shield electrode 18 of the electrode unit 12 has the same potential as the sensor electrode 16.

A pair of terminals (contacts) 24A and 24B are formed in the switch unit 24, and the switch unit 24 switches between connection (on) and non-connection (off) of the pair of terminals 24A and 24B. One terminal 24A of the switch unit 24 is grounded (connected to ground GND), and the other terminal 24B is connected to the output side of the buffer unit 32. As a result, the switch unit 24 sets the shield electrode 18 side of the buffer unit 32 to have a low impedance with respect to the ground GND as the second state and a high impedance with respect to the ground GND as the first state. Switch to the non-grounded state. The shield electrode 18 is grounded when the switch unit 24 to which the terminal 24A and the terminal 24B are connected is on.

A microcomputer is used for the control unit 20, and the control unit 20 uses the electrode unit 12 by the CPU using the RAM as a work memory and reading and executing a program stored in a ROM, a storage, or the like. It functions as a disconnection detection unit that detects the connection state (presence or absence of disconnection) of the operation detection unit and the wiring 30.

The switch units 22 and 24 and the buffer unit 32 are connected to the control unit 20 (the connection with the buffer unit 32 is not shown), and the control unit 20 operates the switch units 22 and 24 and the buffer unit 32. Control.

Here, the control unit 20 detects the capacitance (voltage signal) of the sensor electrode 16 by switching the switch unit 22 to the detection side after setting the switch unit 22 to the power supply side. When the control unit 20 detects the proximity of the operator to the sensor electrode 16 (hereinafter referred to as operation detection), the control unit 20 operates the switch unit 22 with the switch unit 24 turned off and the buffer unit 32 operated. Further, when detecting the presence or absence of disconnection of the wiring 30 (hereinafter referred to as disconnection detection), the control unit 20 turns on the switch unit 24 and operates the switch unit 22 with the buffer unit 32 inactive.

As a result, in the operation detection device 10, the control unit 20 detects the disconnection at preset time intervals while detecting the operation.

The operation detection and disconnection detection using the operation detection device 10 will be described below.
The operation detection device 10 is provided, for example, in a vehicle (not shown). The electrode portion 12 is provided on the rim portion (operator body, not shown) of the steering wheel held by the occupant (driver) as the operator in vehicle steering. The electrode portion 12 is made of a conductive metal rim core metal side in which the shield electrode 18 is arranged in the center of the rim portion, is arranged on the outer periphery of the rim portion, and extends in the circumferential direction of the steering wheel. It is used by being covered with a decorative material such as. As a result, the occupant's hand (or finger) is brought close to the sensor electrode 16 of the electrode portion 12 by the occupant grasping the steering wheel (rim portion) or touching the finger.

The control unit 20 of the operation detection device 10 detects the voltage or voltage change (capacitance or change in capacitance) generated in the sensor electrode 16 to operate whether or not the occupant is gripping the steering wheel. Perform detection. Further, the operation detection of the operation detection device 10 may detect whether or not the occupant has touched the portion of the sensor electrode 16 on the steering wheel.

Here, FIG. 2 shows an outline of the capacitance generated around the sensor electrode 16 in the operation detection device 10. Further, FIGS. 3 (A) and 3 (B) show an outline at the time of operation detection, and FIGS. 4 (A) and 4 (B) show the wiring 30 at the time of detection of disconnection in the non-disconnection state. The outline is shown, and in FIGS. 5A and 5B, the outline at the time of detecting the disconnection in the disconnection state is shown in the wiring 30. Note that FIGS. 3 (A), 4 (A) and 5 (A) show a state in which the operator (operator's finger) is in close proximity, and FIGS. 3 (B), 4 (B) and FIG. FIG. 5B shows the non-proximity state of the operator.

As shown in FIG. 2, in the electrode portion 12, a parasitic capacitance Cp1 is generated in the wiring 30, a parasitic capacitance Cp2 is generated between the sensor electrode 16 and the ground GND, and the shield electrode 18 is connected to the ground GND. A parasitic capacitance Cp3 is generated between them.

Further, in the sensor electrode 16, the capacitance Ct is generated between the sensor electrode 16 and the operator when the operator is brought close to the sensor electrode 16. Further, the sensor electrode 16 has a capacitance Ccc between the sensor electrode 16 and the shield electrode 18. This capacitance Ccc has a shielding function in which the shield electrode 18 faces the entire surface of the sensor electrode 16 so that the capacitance can be larger than the parasitic capacitances Cp1 and Cp2.

When the operation detection is performed, the control unit 20 turns off the switch unit 24 and operates the buffer unit 32. As a result, as shown in FIGS. 3A and 3B, the switch portion 22 (terminal 22C) of the controller 14 is connected to the shield electrode 18 via the buffer portion 32.

Here, when the control unit 20 supplies power to the sensor electrode 16 from the controller 14 with the switch unit 22 as the power supply side, the buffer unit 32 sets the sensor electrode 16 and the shield electrode 18 to the same potential (substantially the same potential). Therefore, the capacitance Ccc between the sensor electrode 16 and the shield electrode 18 can be regarded as substantially zero. Further, the parasitic capacitance Cp2 of the sensor electrode 16 is suppressed by the shield electrode 18.

As a result, as shown in FIG. 3B, when the operator is not close to the sensor electrode 16, the capacitance C generated on the sensor electrode 16 side is larger than the combined capacitance of the parasitic capacitance Cp1 and the parasitic capacitance Cp2. Will also decrease. Further, as shown in FIG. 3A, the capacitance C generated on the sensor electrode 16 side in the state of being close to the sensor electrode 16 of the operator is the capacitance in the non-proximity state (see FIG. 3B). The capacitance is the sum of the capacitance Ct generated between the sensor electrode 16 and the operator. As a result, the capacitance C of the sensor electrode 16 at the time of proximity increases more than the capacitance C of the sensor electrode 16 at the time of non-proximity, and a large amount of electric charge is accumulated in the sensor electrode 16.

The control unit 20 switches the switch unit 22 from the power feeding side to the detection side, and detects a detection signal (voltage signal) generated by the accumulated charge according to the capacitance C. At this time, since the output side of the buffer unit 32 has a high impedance, it is possible to prevent the electric charge accumulated in the shield electrode 18 from affecting the voltage signal detected by the control unit 20.

The control unit 20 compares the detection signal (or the capacitance corresponding to the detection signal) with a preset threshold value. As a result, the operation detection device 10 can detect the operation of the operator on the sensor electrode 16 (whether or not the operator is close to the sensor electrode 16) with high accuracy.

On the other hand, when the disconnection detection is executed, the control unit 20 turns on the switch unit 24 and stops the operation of the buffer unit 32. As a result, as shown in FIGS. 4 (A), 4 (B), 5 (A) and 5 (B), the shield electrode 18 is electrically separated from the sensor electrode 16 and is in a grounded state. Will be done. When the shield electrode 18 is brought into the ground state, the sensor electrode 16 has a large capacitance Ccc as compared with the parasitic capacitances Cp2 and Cp3.

When the wiring 30 is in a non-disconnected state and in a non-proximity state of the operator, when the switch unit 22 is switched to the power feeding side and then to the detection side, the control unit 20 is provided with a capacitance Ccc in the parasitic capacitances Cp1 to Cp3. A detection signal corresponding to the added capacitance C is input (see FIG. 4B). Further, when the wiring 30 is in the non-disconnected state and the operator is in a close state, the control unit 20 receives a detection signal in which the capacitance Ct is added to the capacitance in the non-disconnected state of the wiring 30 and the operator in the non-proximity state. Is input (see FIG. 4 (A)).

On the other hand, as shown in FIGS. 5A and 5B, when the wiring 30 is disconnected, the controller 14 and the sensor electrode 16 are electrically disconnected. As a result, a detection signal corresponding to the parasitic capacitance Cp1 of the wiring 30 is input to the control unit 20 regardless of the proximity or non-proximity of the operator. As a result, the control unit 20 can determine the disconnection of the wiring 30 from the detection signal.

In this way, when the operation detection device 10 detects the proximity of the operator to the sensor electrode 16, the connecting portion 34 sets the sensor electrode 16 and the shield electrode 18 to the same potential. As a result, the parasitic capacitance Cp2 and the capacitance Ccc generated in the sensor electrode 16 can be suppressed, and the presence or absence of proximity of the operator can be detected with high accuracy. Moreover, the connection unit 34 switches between a non-grounded state in which the potential of the shield electrode 18 becomes the same as the potential of the sensor electrode 16 and a grounded state by turning off / off the switch unit 24 and operating / stopping the operation of the buffer unit 32. Therefore, it is possible to easily detect the disconnection between the operation detections.

Further, in the operation detection device 10, the connection portion 34 brings the shield electrode 18 to the ground state when the disconnection of the wiring 30 is detected. As a result, the capacitance generated on the sensor electrode 16 side can be increased regardless of the proximity or non-proximity of the operator, and the difference in capacitance between the disconnected state and the non-disconnected state of the wiring 30 can be increased, and the wiring can be made. The disconnection detection of 30 can be detected with high accuracy.

Further, the operation detection device 10 detects the disconnection between the operation detections while performing the operation detection. As a result, the operation detection device 10 has a small capacitance (voltage signal) because the wiring 30 is disconnected even though the operator is close to the sensor electrode 16. It is possible to prevent erroneous determination that the devices are not close to each other. Therefore, the operation detection device 10 can detect the operation of the operator with high accuracy.

Further, in the operation detection device 10, the switch unit 24 and the buffer unit 32 are provided in the connection unit 34, and the control unit 20 that detects the capacitance (voltage signal) of the sensor electrode 16 controls the switch unit 24 and the buffer unit 32. Then, operation detection and disconnection detection are performed. As a result, the operation detection device 10 can accurately switch between operation detection and disconnection detection to perform operation detection and disconnection detection.

In the present embodiment described above, the electrode portion 12 is provided on the steering wheel to detect whether or not the occupant is gripping the steering wheel or whether or not the sensor electrode 16 is touched. I explained as follows. However, the operating body provided with the electrode portion may be a shift lever or the like, and various operating bodies that the occupant touches and operates in the vehicle can be applied. Further, the operation detection device may detect the contact of the occupant with the operating body, or may detect the touch operation on the sensor electrode.

Further, the operation detection device may be provided not only on the vehicle but also on the operating body that the operator touches and operates in various devices, and the operation detection device may be touch-operated on the sensor electrode portion in the various devices. You may detect whether or not.

10 ... Operation detection device, 12 ... Electrode unit, 16 ... Sensor electrode, 18 ... Shield electrode (opposite electrode), 20 ... Control unit (detection unit, control means), 24 ... -Switch unit (connecting means, switching means), 30 ... wiring, 32 ... buffer unit (connecting means, switching means), 34 ... connecting unit (connecting means).

Claims (2)

A sensor electrode whose capacitance changes with the operator when the operator is brought close to the operator, and an electrode portion having a counter electrode opposed to the side opposite to the operator's proximity side of the sensor electrode.
A detection unit that is connected to the sensor electrode and detects the proximity of the operator to the sensor electrode and the connection state with the sensor electrode by detecting the capacitance.
When the detection unit detects the proximity of the operator to the sensor electrode, the counter electrode is connected to the detection unit so that the potential is the same as that of the sensor electrode, and the detection unit connects the sensor electrode. When detecting the connection state with, the connection portion in which the counter electrode is in the ground state and
Operation detector including. The connection portion includes a switching means for switching between a first state in which the counter electrode has a potential similar to that of the sensor electrode and a second state in which the counter electrode is grounded by being controlled.
The operation detection device according to claim 1, wherein the detection unit includes a control means for controlling the switching means.

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