JPH09178410A - Antipersonnel sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the approach and contact of a human body speedily and securely by outputting a detection signal of logical sum of an electrostatic capacity sensor which detects the approach and contact of the human body based on changes of electrostatic capacity and a pressure sensitive sensor which detects the presence of external pressure. SOLUTION: When a human body approaches a sensor part 42, capacity of a variable capacitor 42 in a resonance circuit 23 is increased first, resonance frequency of the circuit 23 is reduced so that it approaches oscillation frequency of an oscillation circuit 22, and an output of the circuit 23 is increased. Consequently, an output of an OP amplifier 47 is changed over to turn on a switching transistor 52 and output a low level signal from an output terminal 55. Furthermore, when a pressure sensitive element 11 is depressed by the human body, resistance value of pressurized conducting rubber 15 is reduced, a voltage between terminals in a parallel circuit with a relay 12 is reduced, a current which flows in the relay 12 is reduced, and a relay contact 12a is turned on. A detection signal of logical sum of a pressure sensitive sensor 1 and an electrostatic capacity sensor 2 is outputted from an output means 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interpersonal sensor for detecting proximity and contact of a human body.

[0002]

2. Description of the Related Art Conventionally, a pressure-sensitive sensor has been used to detect, for example, seating, to prevent being caught by an automatic door,
Furthermore, emergency stop of machines such as robots is performed. As such a pressure-sensitive sensor, for example, Japanese Utility Model Laid-Open No. 62-5438 discloses a pressure-sensitive element having a structure in which a pressure conductive rubber is sandwiched between a pair of flat braided wire electrodes. In this pressure-sensitive sensor, when the pressure conductive rubber of the pressure-sensitive element is deformed by an external force, the resistance value between the pair of flat braided wire electrodes changes, so that the external force acts based on the change in the resistance value. Is detected.

Further, for example, in Japanese Unexamined Patent Publication (Kokai) No. 62-37434, a capacitance element is connected to the output end of an oscillation circuit so that the capacitance changes when a human body is seated, and this capacitance element is passed through. Disclosed is a capacitance type sensor that detects the sitting of a human body based on a comparison between an oscillation output and a reference value.

[0004]

However, in the above-mentioned pressure-sensitive sensor, it is possible to detect that the external force acts for the first time because the pressing conductive rubber of the pressure-sensitive element is deformed by the external force. When the human body is seated, detection may be insufficient if a sufficient load is not applied. Further, in preventing the automatic door from being pinched, the pressure-sensitive sensor detects only when the door is pinched, and thus the initial purpose may not be sufficiently achieved. Similarly, even in the case of an emergency stop of a machine such as a robot, the pressure-sensitive sensor detects it only after a collision, so that the initial purpose may not be sufficiently achieved.

Further, in the above-mentioned capacitance type sensor, not only the conductor such as metal but also the dielectric can be detected without contact as an object to be detected, and the object to be detected has the transparency, Although it has the advantage that it can be detected without being affected by color, dirt, surface roughness, etc., it is susceptible to the ambient temperature and the grounding state of the surrounding metal because the circuit is constructed using resistors and capacitors. There is.

The present invention has been made in view of the above points, and makes it possible to detect the proximity and contact of a human body promptly and reliably by taking advantage of the capacitance type sensor and solving the problem. It is intended to provide a highly reliable interpersonal sensor that is appropriately configured.

[0007]

In order to achieve the above object, the human sensor of the present invention is provided with a pair of flexible conductive members and a pressure conductive rubber provided between these flexible conductive members. A pressure sensitive sensor having a pressure sensitive element, which detects the presence or absence of external pressure based on a change in the resistance value of the pressure sensitive element; and at least one flexible conductive member of the pressure sensitive element as one electrode, the ground side Having a capacitive element having the other electrode as the other electrode, and based on a change in electrostatic capacitance thereof, a capacitive sensor for detecting proximity or contact of a human body, and a logical sum of the pressure-sensitive sensor and the capacitive sensor. And output means for outputting the detection signal of.

In a preferred embodiment of the present invention, the pressure-sensitive sensor has a relay connected in parallel with the pressure-sensitive element and selectively turned on / off based on a change in resistance value of the pressure-sensitive element. The capacitance sensor is coupled to a coupling transformer having a primary side coil and a secondary side coil, an oscillation circuit coupled to the primary side coil of the coupling transformer, and a secondary side coil of the coupling transformer. A resonance circuit having the capacitive element, and a comparison circuit for comparing the output of the resonance circuit with a reference value, the output means has a switching transistor and a relay contact of the relay,
The base of the switching transistor is coupled to the output terminal of the comparison circuit, and the relay contact is connected to the bias path of the switching transistor.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of an embodiment of an interpersonal sensor of the present invention. This interpersonal sensor includes a pressure-sensitive sensor 1 for detecting the presence or absence of external pressure by the human body,
An electrostatic capacitance type sensor 2 that detects proximity and contact of a human body based on a change in electrostatic capacitance, and an output unit 3 that outputs a detection signal of a logical sum of the pressure sensitive sensor 1 and the electrostatic capacitance type sensor 2. Have.

The pressure-sensitive sensor 1 has a pressure-sensitive element 11 and a relay 12 which are connected in parallel, and one end of a parallel circuit thereof is connected to a voltage Vcc via a choke coil 13a and a resistor 14.
Connect to the positive terminal of DC power supply No. 1 and the other end to choke coil 1
It is grounded via 3b, that is, connected to the negative terminal of the DC power supply.
As shown in FIG. 2, the pressure-sensitive element 11 includes a pair of flat braided wire electrodes 16a and 16b sandwiching a pressure conductive rubber 15 whose resistance value changes due to deformation due to external pressure, and the whole is molded with a silicone rubber 17. Use the one that you made. In FIG.
The pressure conductive rubber 15 is shown by a variable resistance, and the flat braided wire electrode 16 is shown.
a and 16b are shown in the shape of terminals. The resistor 14
The resistance value of is small when the pressure conductive rubber 15 is not deformed, the relay 12 maintains the energized (ON) state, the pressure conductive rubber 15 is deformed by an external force, and the resistance value is small. The relay 12 is set to be deenergized (off) when it becomes.

The capacitance type sensor 2 is a coupling transformer 2.
1, an oscillation circuit 22, a resonance circuit 23, a rectification circuit 24, and a comparison circuit 25. The oscillator circuit 22 is an LC that uses the primary coil 21a of the coupling transformer 21 as an inductive element.
Configured with an oscillator circuit. This oscillator circuit 22 has 2
NPN transistors 31 and 32 are provided, and the collector of one transistor 31 is connected to a voltage V
It is connected to the positive terminal of the DC power source of cc2, and the emitter is grounded via the parallel circuit of the capacitor 34 and the resistor 35. The bases of the transistors 31 and 32 are commonly connected to form a resistor 3
Connect to the DC power source positive terminal (Vcc2) via 6. The collector of the transistor 32 is open, the emitter is grounded via the primary coil 21a of the coupling transformer 21, and the transistor 31 is connected via the capacitor 37.
Connect to the emitter of. In this way, the capacitor 3
An LC oscillating circuit in which the electric potentials at both ends of 7 are made approximately the same electric potential is formed. In this embodiment, the oscillation frequency f of the oscillator circuit 22 is about 500 KHz at room temperature of 20 ° C.

The resonance circuit 23 has a secondary coil 21b of the coupling transformer 21, a capacitor 41 and a variable capacitor 42 as a detecting capacitive element. The variable capacitor 42 is a flat braided wire electrode of at least one of the pressure-sensitive elements 11, so that the electrostatic capacitance changes due to the proximity and contact of the human body.
In this embodiment, the flat braided wire electrode 16b is used as one electrode,
The ground side is configured as the other electrode. Secondary coil 21
b and the capacitor 41 are connected in parallel, one end thereof is grounded, and the other end thereof is connected to the flat braided wire electrode 16b of the pressure sensitive element 11 which is one electrode of the variable capacitor 42. In this embodiment, the sensor unit 4 includes the portion having the pressure sensitive element 11 and the portion constituting the variable capacitor 42, and a human body approaches the sensor unit 4 or the pressure sensitive element 1
The circuit constant is set so that the resonance frequency of the resonance circuit 23 is slightly higher than the oscillation frequency of the oscillation circuit 22 when the human body is not in contact with 1.

The output of the resonance circuit 23, that is, the flat braided wire electrode 16b which is one electrode of the secondary coil 21b of the coupling transformer 21, the capacitor 41 and the variable capacitor 42.
The output of the connection point is supplied to the rectifier circuit 24 via the coupling capacitor 43. The rectifier circuit 24 includes a diode 44.
Double voltage circuit consisting of a and 44b, and capacitor 4
5, a low-pass filter having a resistor 46 is provided, and the output of the rectifier circuit 24 is supplied to the comparison circuit 25.

The comparison circuit 25 includes an OP amplifier 47 and a resistor 4.
8 and a variable resistor 49, the output of the rectifier circuit 24 is applied to the non-inverting input terminal of the OP amplifier 47, and the DC voltage Vcc3 is divided by the resistor 48 and the variable resistor 49 into the inverting input terminal of the OP amplifier 47. The applied reference voltage is applied. The reference voltage is applied to the OP amplifier 47 when the human body does not approach the sensor unit 4 or the human body does not contact the pressure sensitive element 11.
Is slightly higher than the voltage applied to the non-inverting input terminal of the OP amplifier 47, and is applied to the non-inverting input terminal of the OP amplifier 47 when the human body approaches the sensor unit 4 or the human body contacts the pressure-sensitive element 11. Set to a voltage lower than the specified voltage. The output of the OP amplifier 47 is the backflow prevention diode 51.
And is supplied to the output means 3.

The output means 13 is an NPN type switching transistor 52, a collector resistor 53, and a base resistor 54.
And the relay contact 1 of the relay 12 provided in the pressure-sensitive sensor 1.
2a, the collector of the switching transistor 52 is connected to the output terminal 55, the collector resistance 53 is connected to the DC power supply positive terminal of the voltage Vcc4, the emitter is grounded, and the base is connected to the base resistance 54 to prevent reverse current. It is connected to the anode terminal of the diode 51. The relay contact 12a is connected between the connection point of the base resistor 54 and the reverse current blocking diode 51 and the DC power supply positive terminal (Vcc4). The relay contact 12a is the relay 1
Under the depletion of 2, use normally closed contacts in the on state.

In this embodiment, the voltage Vcc1 is 24 volts and the voltages Vcc2, Vcc3 and Vcc4 are 5 volts, but each voltage can be set arbitrarily and all can be the same voltage.

Next, the operation of the interpersonal sensor shown in FIG. 1 will be described. When the human body is not in contact with or in contact with the sensor unit 4, the resistance value of the pressure conductive rubber 15 of the pressure sensitive element 11 is a high value, so the relay 12 is in the energized state and the relay contact. 12a is open. Further, in this state, the resonance frequency of the resonance circuit 23 is slightly higher than the oscillation frequency of the oscillation circuit 22, so the output of the OP amplifier 47 is at a low level. Therefore, the switching transistor 52 is in an off state, and a high level signal is output from the output terminal 55.

When the human body approaches the sensor unit 4 from the above state, the capacitance of the variable capacitor 42 of the resonance circuit 23 increases first, and the resonance frequency of the resonance circuit 23 becomes the oscillation circuit 2.
The output of the resonance circuit 23 increases because it decreases as it approaches the oscillation frequency of 2. As a result, the OP amplifier 47
Output switches from low level to high level, the switching transistor 52 is turned on, and a low level signal is output from the output terminal 55.

When the human body approaches the sensor unit 4 and the human body further presses the pressure-sensitive element 11, the deformation of the pressure-sensitive conductive rubber 15 lowers the resistance value of the pressure-conductive rubber 15. The voltage between the terminals decreases, and the current flowing through the relay 12 decreases. As a result, the relay 12 is deenergized, the relay contact 12a is turned on, and the bias voltage is applied to the switching transistor 52 via the relay contact 12a. Therefore, even if the human body approaches the sensor unit 4 due to a change in ambient temperature,
Even if the output of the P amplifier 47 does not go high,
When the pressure sensitive element 11 is pressed, the switching transistor 52 is turned on and a low level signal is output from the output terminal 55, so that the contact of the human body with the sensor unit 4 can be detected.

As described above, according to this embodiment, the approach of the human body to the sensor unit 4 is detected by the capacitance type sensor 2 based on the change in the capacitance of the variable capacitor 42, and the sensor unit 4 is further detected. The pressure-sensitive element 1 of the pressure-sensitive sensor 1 indicates that the pressure-sensitive element 11 of No. 4 is pressed by the human body.
Since the detection signal of the logical sum of the pressure sensitive sensor 1 and the capacitance type sensor 2 is output from the output means 3 by detecting based on the resistance change of 1, the proximity and contact of the human body can be quickly And it can be detected reliably. Therefore, for example, in the case of applying to a power window control circuit of an automobile, by providing the pressure-sensitive element 11 in the window frame portion where the window glass is raised and comes into contact with and pressed, the window frame is not lifted while the window glass is being raised. When a hand or a head is inserted between the window glass and the window glass, the window glass can be stopped from rising based on the output of the output terminal 55 due to the capacitance change of the variable capacitor 42. Therefore, even if the electrostatic capacitance cannot be detected, the pressure-sensitive element 11 in the window frame portion
The rising of the window glass can be stopped by the output of the output terminal 55 based on the resistance change caused by pressing.

The present invention is not limited to the above-described embodiment, but various modifications and changes can be made. For example, in the above-described embodiment, the oscillator circuit 2
2 and the resonance circuit 23 are configured by using the primary side coil 21a and the secondary side coil 21b of the coupling transformer 21, respectively, the oscillation circuit 22 and the resonance circuit 23.
Is provided separately from the coupling transformer 21, and the oscillation circuit 22
Of the coupling transformer 21 and the output of the secondary coil 21b of the coupling transformer 21 to the resonance circuit 23. In addition, the oscillator circuit 22
The configuration is not limited to that shown in FIG. 1, and a known LC oscillation circuit or another oscillation circuit can be used.

Further, in FIG. 1, the pressure sensor 1 is connected to the relay 1
2, the relay 12 is energized / deenergized based on the resistance change of the pressure sensitive element 11 to detect the deformation of the pressure sensitive element 11, that is, the pressing by the human body. For example, by using a photocoupler having a light emitting diode and a phototransistor, and turning on and off the light emitting diode based on the resistance change of the pressure sensitive element 11, the pressure sensitive element 11 can be deformed from conduction / non-conduction of the phototransistor. It can also be configured to detect. Further, the output means 3 can be configured by using a bipolar IC or a MOS IC, and the signal output from the output terminal 55 of the output means 3 can be a high level signal due to the proximity of the human body to the sensor unit 4 or the like. It can also be configured to output.

[0023]

As described above, according to the present invention, the presence or absence of external pressure is detected by the pressure-sensitive sensor having the pressure-sensitive element, and at least one of the flexibility of the pressure-sensitive element is configured. A capacitive sensor having a capacitive element with the conductive member as one electrode and the ground side as the other electrode is used to detect the proximity and contact of the human body, and the pressure sensor and the capacitive sensor Since the logical sum detection signal is output, it is possible to obtain a highly reliable interpersonal sensor that can detect proximity and contact of the human body quickly and reliably while taking advantage of the advantage of the capacitance type sensor.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an example of the pressure-sensitive element shown in FIG.

[Explanation of symbols]

 1 Pressure Sensitive Sensor 2 Capacitive Sensor 3 Output Means 4 Sensor Section 11 Pressure Sensitive Element 12 Relay 12a Relay Contact 15 Pressurized Conductive Rubber 16a, 16b Flat Braided Wire Electrode 21 Coupling Transformer 22 Oscillation Circuit 23 Resonance Circuit 24 Rectifier Circuit 25 Comparison Circuit 42 Variable Capacitor 52 Switching Transistor 55 Output Terminal

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G01V 11/00 G01V 11/00

Claims (2)

[Claims] 1. A pressure-sensitive element comprising a pair of flexible conductive members and a pressure conductive rubber provided between the flexible conductive members, and based on a change in resistance value of the pressure-sensitive element. A pressure-sensitive sensor for detecting the presence or absence of external pressure, and a capacitive element having at least one flexible conductive member of the pressure-sensitive element as one electrode and the ground side as the other electrode, and its capacitance change Based on the above, an interpersonal person characterized by comprising an electrostatic capacity sensor for detecting proximity and contact of a human body, and an output means for outputting a detection signal of a logical sum of the pressure sensitive sensor and the electrostatic capacity sensor. Sensor. 2. The interpersonal sensor according to claim 1, wherein the pressure-sensitive sensor is connected in parallel to the pressure-sensitive element and is selectively turned on / off based on a change in resistance value of the pressure-sensitive element. The capacitive sensor includes a coupling transformer having a primary side coil and a secondary side coil, an oscillation circuit coupled to the primary side coil of the coupling transformer, and a coupling to a secondary side coil of the coupling transformer. And a comparison circuit for comparing an output of the resonance circuit with a reference value, the output means having a switching transistor and a relay contact of the relay, and the switching transistor. Is connected to the output terminal of the comparison circuit and the relay contact is connected to the bias path of the switching transistor. Sa.