JPH0226825B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a door opening/closing switch that opens and closes a door when a person or other moving object approaches.

The conventional door opening/closing switch (see Figure 1) has a capacitor 3 buried in the ground near the door as a detector whose capacitance changes due to the approach of a person or other moving object, and the output voltage of the oscillator 1 is set to a known value. The voltage is applied to a circuit in which a capacitor 2 and a capacitor 3 are connected in series, and the voltage applied to the capacitor 3 is detected to detect the approach of a person or other moving object.

However, when using the conventional door opening/closing switch described above, the oscillator 1 and the detection circuit 4 must be installed near the installation position of the capacitor 3 in order to directly detect the capacitance change of the capacitor 3 as a voltage change. It was hot.

The present invention has been made in view of the above, and eliminates the above-mentioned drawbacks, and makes it possible to install an electric circuit such as a detection circuit at a position away from a capacitor serving as a detector, thereby easing restrictions on the installation position. The purpose is to provide a door opening/closing switch, and in order to achieve this purpose, a change in capacitance of a capacitor due to the approach of a person or other moving object is treated as detuning of two resonant circuits. is the technical issue.

The present invention includes an oscillator, a capacitor as a detector that is buried close to the door and whose capacitance changes as a moving object approaches, and an oscillation output of the detector is applied and the oscillation frequency of the oscillator is set as a resonance frequency. The oscillation output of an oscillator is applied to a first resonant circuit and a capacitor as part of the components, and when a moving object does not approach, the oscillation frequency of the oscillator is set as a resonant frequency, and when detuned, the external signal causes a transition to a resonant state. A second resonant circuit is subtracted from the respective output voltages detected from the second resonant circuit, which are in opposite phases to each other, and a resonant output voltage separately detected from the first resonant circuit, and the subtracted output is output. A detection circuit applies a signal as an external signal to the second resonant circuit, and a subtraction output signal from this detection circuit is input, and the door is closed for a time set by a delay circuit only when the subtraction output signal increases. It is configured to include means for outputting a signal for driving in the opening direction.

The present invention will be explained below with reference to the embodiments shown in FIGS. 2 and 3.

Capacitor 5 that resonates at the oscillation frequency of oscillator 1
A first parallel resonant circuit consisting of a coil 6 and a coil 6 is connected to the oscillator 1, and a second parallel resonant circuit consisting of a coil 7 that resonates at the oscillation frequency of the oscillator 1, capacitors 8 and 9, a variable capacitance diode 10, and a capacitor 3 as a detection circuit is connected to the oscillator 1. A parallel resonant circuit is connected to the oscillator 1.

Note that the capacitor 3 is buried in the ground near the door via a coaxial cable 11.

12 is a coil that takes out the resonant output of the first parallel resonant circuit, and 13 is a coil that takes out the output of the second parallel resonant circuit.

The middle point of the coil 13 is drawn out, and the coil winding direction from the middle point to one end is opposite to the coil winding direction from the middle point to the other end, and the middle point is drawn out from the coil 12. The coil 13 is connected to one end of the parallel resonant circuit, and the coil 13 takes out the outputs of the second parallel resonant circuit with opposite polarities, and the coil 12 takes out the outputs of the first parallel resonant circuit.
It is configured to add the resonant output of the parallel resonant circuit.

One end of the coil 13 is connected to a diode 14 and a resistor 16.
The other end of the coil 13 is connected to a second detection circuit consisting of a diode 17, a resistor 19, and a capacitor 18.

The output voltage of the second detection circuit and the output voltage of the first detection circuit are applied to the detection circuit 20, and the output voltage of the first detection circuit is subtracted from the output voltage of the second detection circuit. The output voltage is applied to the variable capacitance diode 10 of the second parallel resonant circuit to restore the second parallel resonant circuit to a resonant state.

That is, since the variable capacitance diode 10 has a characteristic that its capacitance decreases as the applied voltage increases, if a moving object approaches the capacitor 3 from the state where the second parallel resonant circuit is resonating, By increasing the capacity of the second parallel resonant circuit, the second
The output voltage of the parallel resonant circuit becomes larger than the output voltage of the first parallel resonant circuit, and as a result, the voltage value of the subtracted output signal, which is the output signal of the detection circuit 20, increases, and the capacitance of the variable capacitance diode 10 increases. As a result, the second parallel resonant circuit returns to a resonant state and maintains that state due to the reduction in the capacitance of the variable capacitance diode 10.

Further, the subtracted output signal from the detection circuit 20 is directly applied to the differential amplifier 22 through a delay circuit 21 consisting of a low-pass filter, and the differential amplifier 2
The output of No. 2 is applied to a comparator 23 having hysteresis, and the output of this comparator 23 is used as a signal for driving the door in the opening direction.

That is, the delay circuit 21, the differential amplifier 22, and the comparator 23 input the subtraction output signal from the detection circuit, and only when the subtraction output signal increases and changes, the door is closed for a period of time set by the delay circuit. This constitutes means for outputting a signal for driving in the opening direction.

To explain more specifically, the delay circuit 21
has a delay circuit section consisting of a resistor and a capacitor in which diodes in reverse orientation are connected in parallel, and when the subtraction output signal input to the delay circuit 21 rises, the delay circuit part is composed of a resistor and a capacitor. When descending, due to the action of the diode connected in the opposite direction, the subtracted output signal is simultaneously input to the differential amplifier 22 directly. is applied to the dynamic amplifier 22.

That is, when a moving object approaches the capacitor 3 and the subtracted output signal of the detection circuit 20 rises, the increased subtracted output signal is directly applied to one input terminal of the differential amplifier 22; This increased subtraction output signal is applied after a delay of a time set by the delay circuit 21. Therefore, the differential amplifier 22 is
It will output only during the time set in 1.

In this embodiment configured as described above, when no moving object approaches the position where the capacitor 3 is buried as a detector, the capacitance of the capacitor 3 does not change, and the second parallel resonant circuit is connected to the oscillator 1. It is in a resonant state at the oscillation frequency.

Therefore, as shown in the upper half of FIG. 3a, one end of the coil 13 is connected to the voltage OA detected by the coil 12 to detect the resonance output of the first parallel resonance circuit, and the resonance output of the second parallel resonance circuit to the coil 13. The sum voltage OABR of the voltage BR detected at one side winding of 13 is output.

In addition, as shown in the lower half of FIG. 3a, the other end of the coil 13 is connected to the voltage OA detected by the coil 12 to detect the resonant output of the first parallel resonant circuit, and the resonant output of the second parallel resonant circuit to the coil 13. The sum voltage OAB'R of the voltage B'R (which has the opposite polarity to the voltage BR) detected at the other winding of the 12 windings is output.

The voltage OABR is detected by the first detection circuit,
Voltage OAB'R is detected by a second detection circuit.

However, as is clear from Figure 3a, the voltage
Since OABR and voltage OAB'R are equal, the output of the detection circuit 20, that is, the subtraction output signal, is zero,
The output of the differential amplifier 22 is zero, and the output of the comparator 23 remains at a high potential, so that no drive signal is output in the direction to open the door.

Next, as shown in Figure 3b, when a human or other moving object approaches the buried position of the capacitor 3 as a detector, the capacitance on the capacitor 3 side increases due to the stray capacitance of the moving object, and The parallel resonant circuit becomes detuned.

Therefore, as shown in the upper half of FIG. The sum voltage OABN with the voltage BN detected on one side of the winding is output.

Further, as shown in the lower half of FIG. The sum voltage OAB'N of the voltage B'N (which has the opposite polarity to the voltage BN) detected at the other side winding is output.

The voltage OABN is detected by the first detection circuit,
Voltage OAB'N is detected by a second detection circuit.

However, as is clear from Figure 3c, the voltage
Since OABN<voltage OAB'N, the detection circuit 20 outputs the difference voltage between the two voltages as a subtracted output signal.

The subtracted output signal, which is this differential voltage, is applied to the variable capacitance diode 1 of the second parallel resonant circuit which is in a detuned state.
0 is applied to decrease the capacitance of the variable capacitance diode 10, so that the second parallel resonant circuit returns to the resonant state again.

In addition, this subtracted output signal is directly transmitted to the differential amplifier 2.
2 is applied to one input terminal of the differential amplifier 2, and is inputted to the other input terminal after being delayed by the set time through the delay circuit 21. During the time set by the delay circuit 21, the differential amplifier 22 A differential voltage is output, and this output causes the comparator 23 to output a low-potential door drive signal.

As mentioned above, since the second parallel resonant circuit returns to the resonant state by the subtracted output signal, this second
The output of the detection circuit 20, that is, the subtracted output signal, is returned to zero by the return of the second parallel resonant circuit to the resonant state. The door will be held open until the subtracted output signal decreases and the output voltage of the comparator 23 becomes a high potential.

During the period when this door is open, comparator 2
3 and the time constant of the delay circuit 21.

As is clear from the above description, according to the present invention, by using a capacitor as a detector as a component of a resonant circuit, the capacitor as a detector can be installed at a desired position using a coaxial cable. Therefore, the detector and circuits other than the detector can be provided at separate locations.

[Brief explanation of drawings]

FIG. 1 shows a block diagram of a conventional door opening/closing switch. FIG. 2 is a circuit diagram showing one embodiment of the present invention. FIG. 3 is a diagram for explaining the operation of one embodiment of the present invention. Explanation of symbols 1: Oscillator, 3: Capacitor as a detector, 5: Capacitor forming the first parallel resonant circuit, 6: Coil forming the first parallel resonant circuit, 7: Second parallel resonant circuit. Constituent coils, 8 and 9; Capacitor, 10, which constitutes the second parallel resonant circuit; Variable capacitance diodes, 12 and 13; Coil, 20, which takes out the output voltage of the first and second parallel resonant circuits; Detection circuit, 21;
Delay circuit, 22; differential amplifier, 23; comparator.

Claims (1)

[Claims] 1. An oscillator, a capacitor as a detector buried close to the door and whose capacitance changes with the approach of a moving object, and a first capacitor to which the oscillation output of the oscillator is applied and whose resonance frequency is the oscillation frequency of the oscillator.
and a resonant circuit including the capacitor as a component, to which the oscillation output of the oscillator is applied, and when the moving object does not approach, the oscillation frequency of the oscillator is set as the resonant frequency, and when detuned, it is brought into a resonant state by an external signal. Subtracting the second resonant circuit to which the transition occurs, the respective output voltages detected from the second resonant circuit that are in opposite phases, and the sum of the resonant output voltages separately detected from the first resonant circuit. and a detection circuit that applies a subtraction output signal to the second resonant circuit as the external signal, and a time set by a delay circuit that inputs the subtraction output signal from the detection circuit and only when the subtraction output signal increases and changes. During the
A door opening/closing switch comprising: means for outputting a signal for driving the door in the opening direction.