JPS5824077A - Touch switch for door opening and closing apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a touch switch for a door opening/closing device for detecting whether a passenger is getting on or off a vehicle.

Traditionally, vehicles such as buses have been equipped with touch switches to detect whether or not passengers are getting on or off the vehicle, in order to prevent the doors from closing suddenly and trapping passengers in the door. ,
Pressure is applied to keep the door in the open position when passengers are boarding and exiting the vehicle.

As a conventional touch switch for a door opening/closing device, an antenna placed near the doorway that can be touched by a person is connected to the antenna, and the touch switch responds to the change in capacitance that occurs when a person touches the antenna. , which is equipped with a frequency oscillator whose oscillation frequency changes and a discriminator which discriminates changes in the oscillation frequency of the frequency oscillator, and detects whether a person is touching the antenna based on the output of the discriminator. Are known.

Incidentally, conventionally, a resonant circuit is used as a discriminator for discriminating changes in the oscillation frequency of a single-frequency oscillator.

The oscillation frequency of the frequency oscillator when a person is not in contact with the antenna is set to match the resonant frequency of the resonant circuit, and the oscillation frequency of the frequency oscillator is set to match the resonant frequency of the resonant circuit. Although contact is detected, the oscillation frequency of commonly used frequency oscillators easily changes when the environmental temperature changes, etc.
Furthermore, since the resonant frequency band of the resonant circuit is narrow, when the oscillation frequency changes due to changes in the environmental temperature, etc., the resonant state is canceled and there is a problem in that false information that a person is in contact with the antenna is generated. In addition, to solve this problem, it is necessary to use a high-precision frequency oscillator to keep the oscillation frequency constant with high precision when five people are not touching the antenna, which is economically expensive. There is a drawback.

This invention was made in view of the above-mentioned problems, and provides a touch switch for a door opening/closing device that ensures stable operation regardless of slight fluctuations in the oscillation frequency due to the influence of environmental temperature, etc. of a dual frequency oscillator. The object of the present invention is to provide a discriminator for discriminating changes in the oscillation frequency of a single-frequency oscillator, which is configured with a phase locked circuit comprising a phase detector, a low-pass filter, and a voltage or current controlled oscillator. , the oscillation frequency signal of the frequency oscillator is used as the input signal of the phase detector.

In other words, a phase-locked circuit consisting of a phase detector, a low-pass filter, and a voltage- or current-controlled oscillator and having a predetermined synchronous frequency band with respect to the frequency of an input signal is used as a discriminator for determining changes in the oscillation frequency of the frequency oscillator. Even if the oscillation frequency of the single-frequency oscillator fluctuates slightly due to changes in temperature, etc., the periodic frequency band has a predetermined width, so there is no need to worry about erroneous differences due to slight frequency fluctuations. .

Embodiments of the present invention will be described below with reference to the drawings.

In the figure, the phase synchronization circuit indicated by reference numeral 1 includes a 1-phase detector 2, a voltage controlled oscillator 3, and a capacitor 4 forming a low-pass filter. The input signal terminal 5 of the phase detector 2 is connected via a capacitor 6° line 7 to a frequency oscillator 8, which will be detailed later, and the other input terminal 9 is connected via a line 10 to an output terminal 11&C of the voltage controlled oscillator 3. The output terminal 12 is connected to the resistor 13. It is connected via a line 14 to an input terminal 15 of the voltage controlled oscillator 3. Also, line 1
4 is connected to a capacitor 4. Voltage controlled oscillator 3
The capacitor 16% resistor 17 connected to is used to set the voltage controlled oscillator 30 frequency band to a predetermined value, and is set to a predetermined value corresponding to the frequency oscillator 80 frequency. Note that the power supply terminals 18 and 19 of the 1-phase detectors 2 and 3 are connected to a constant voltage power supply line 20.

The above phase detector 2 and voltage controlled oscillator 3 have conventionally known structures, and the phase detector 2 detects the phase difference between the output signal of the voltage controlled oscillator 3 and the input signal transmitted to the input terminal 5. , an output signal of a voltage corresponding to the phase difference is outputted from the output terminal 12.

The AC component of this output signal is removed by the low-pass filter 4 and transmitted to the input terminal 15 of the voltage controlled oscillator 3. The voltage controlled oscillator 3 changes the frequency of the output signal in a direction that eliminates the phase difference according to the input signal. Therefore, when the frequency of the signal transmitted to the input terminal 5 of the 1-phase detector 20 is within the frequency band of the voltage controlled oscillator 3, 1
The phase synchronization circuit 1 is in a synchronous state, and the signal on the line 14 is at a high potential.When the frequency of the signal transmitted to the input terminal 5 is lower than the above frequency band, synchronization is not achieved and the signal on the line 14 is at a low potential. It is electric potential.

The frequency oscillator 8 includes a differential amplifier 21 , and its positive input terminal 22 is connected to the constant voltage power supply line 2 via a resistor 23 .
0 and grounded via a resistor 24, and connected to an output terminal 26 via a resistor 25. Further, the negative terminal 27 is connected to the output terminal 26 via a resistor 28 and grounded via a capacitor 29. The output terminal 26 is connected to the constant voltage power supply line 20 via a resistor 30, and is connected to the constant voltage power supply line 20 via a resistor 31.
The line 7 is connected to a line 7 via a resistor 32, and the line 7 is grounded via a resistor 32. Reference numeral 33 denotes an antenna, which is constituted by a grip bar placed near the doorway, and is connected to the line 7. Therefore, if a passenger touches the antenna 33 when getting on or off, the
The human body acts as a capacitor and generates a capacitance between the wire 7 and the ground corresponding to the capacitor 34. Therefore, when no person is in contact with the antenna 33, the one-frequency oscillator 8 generates a signal with a frequency determined by the resistor 28 and the capacitor 29, and this frequency is approximately the center value of the frequency band of the voltage-controlled oscillator 3. And then,
When a person touches the antenna, it is equivalent to connecting a capacitor 34 between line 7 and ground. Therefore, the oscillation frequency of the one-frequency oscillator 8 is affected by the equivalent capacitor 34, and the oscillation frequency is lowered, and the voltage-controlled oscillator 3
It will be outside the frequency band of

35 is a differential amplifier constituting a comparator, and its positive input terminal 36 is connected to the constant voltage power supply line 20 via a resistor 37.
is grounded via a resistor 38, and its negative input terminal 39 is connected to the constant voltage power supply line 20 via a resistor 40 via a capacitor 41, and the phase is connected via a resistor 42 and a source follower 43. It is connected to the line 14 of the synchronous circuit 1. The source follower 43 is an impedance converter for preventing the influence of the circuit on the comparator 35 side from reaching the phase-locked circuit IK, and the capacitor 41 is an alternating current of the signal transmitted to the input terminal 39 of the differential amplifier 35. This is for smoothing the components. Output terminal 44 of differential amplifier 35
is connected to the constant voltage power supply line 20 via a resistor 45 and to the base of an output transistor 47 via a resistor 46. A smoothing capacitor 48 is interposed between the pace of the transistor 47 and the ground, and its emitter is grounded. A relay coil 51 is connected between the collector of the transistor 47 and a power line 50 connected to a power source 49, and when the coil 51 is energized, the relay is activated.
The door is held in the open position via a control circuit (not shown). 52 is an arc-extinguishing diode connected in parallel to the coil 51.

53 is a resistor, and 54 is a Zener diode. The resistor 53 and the Zener diode 54 constitute a constant voltage circuit that keeps the voltage of the constant voltage power supply line 20 constant.

The operation, etc. of the embodiment of the present invention configured as above will be explained.

When the antenna 33 is not touched by a person, the oscillation frequency of the frequency oscillator 8 is approximately at the center of the frequency band of the voltage controlled oscillator 3. This oscillation frequency signal is transmitted via line 7 and capacitor 6 to input signal terminal 5 of phase detector 20. If there is a frequency difference, that is, a phase difference, between the signal transmitted to the input signal terminal 5 and the signal from the voltage controlled oscillator 3, a voltage signal corresponding to the phase difference is transmitted to the voltage controlled oscillator via the line 14. 3, the oscillation frequency of the voltage controlled oscillator 3 quickly changes in the direction of zeroing the phase difference and matches the frequency transmitted to the input signal terminal 5, that is, the phase synchronized circuit 1 is in a synchronized state. become. In this synchronized state, there is no longer an alternating current signal at the output terminal 12 of the phase detector 2, and the potential of the line 14 is at a high potential.

This high potential is transmitted to the negative input terminal 39 of the differential amplifier 35 via the source 7 orer 43 and the resistor 42, and the potential of this terminal 39 is kept higher than the reference voltage of the positive input terminal 36. Therefore, the output of the differential amplifier 35 is at a low potential and the four output transistors are non-conductive.

If the frequency oscillator 8
Even if the frequency of the voltage-controlled oscillator 3 changes slightly from the equal voltage change of the power supply voltage, as long as the frequency change is within the frequency band of the voltage-controlled oscillator 3, the frequency of the voltage-controlled oscillator 3 immediately follows the frequency change, Synchronization will never be released.

Now, when a person comes into contact with the antenna 33, a capacitance equivalent to the capacitor 34 is created between the wire 7 and the ground, and the oscillation frequency of the frequency oscillator 8 is significantly lowered due to this capacitance. Therefore, the frequency of the signal transmitted to the input signal terminal 5 of the phase detector 20 falls outside the frequency band of the voltage controlled oscillator 3, and the oscillation frequency of the voltage controlled oscillator 3 can no longer be followed, and the synchronized state of the phase locked circuit 1 changes. Release, line 14
potential decreases. As a result, the potential at the negative input terminal 39 of the differential amplifier 35 becomes lower than the reference potential at the positive input terminal 36, the output of the operating voltage amplifier 35 becomes high potential, and the output transistor 47 becomes conductive. Coil 51 is excited. This excitation of the coil 51 activates the control circuit to hold the door in the open/closed position.

When the person leaves the antenna 33 again, the oscillation frequency of the frequency oscillator 8 returns to the original frequency, and the one-phase synchronization circuit 1 becomes synchronous, and the output transistor 47 becomes non-conductive due to the same effect as described above.

As is clear from the above description, the present invention provides a discriminator that detects changes in the oscillation frequency of a frequency oscillator that changes due to one person's contact with an antenna, which is composed of a five-phase detector, a low-pass filter, and a voltage or current controlled oscillator. Since it is configured with a phase-locked circuit, the frequency of the frequency oscillator changes with changes in the environmental temperature.

Even if the power supply voltage deviates slightly from the equal voltage, there is no fear that the synchronization will be canceled and an erroneous signal will be output because the phase synchronization circuit has a predetermined synchronization frequency band.

In addition, since the phase synchronized circuit has a predetermined synchronized frequency band, the frequency accuracy of a single frequency oscillator is not required to be %: an ordinary oscillator can be used, and the constant voltage circuit can also have a simple configuration, making it economical. can be produced at low cost.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be modified in many ways within the scope of the technical idea of the fifth invention.

For example, in the embodiment, a voltage controlled oscillator is used as the controlled oscillator of the phase locked loop, but a current controlled oscillator may be used instead.

[Brief explanation of the drawing]

The figure is a circuit diagram showing one embodiment of the present invention. 1... Phase synchronized circuit 2... Phase detector 3...
Voltage controlled oscillator 4... Capacitor (Rono (Sfilter)) 8... Frequency oscillator 21... Differential amplifier 33... Antenna 43... Source follower
47...output transistor

Claims (1)

[Claims] An antenna placed near the door that can be touched by a person, a frequency oscillator connected to the antenna and whose oscillation frequency changes according to the change in capacitance that occurs when a person touches the antenna, and its frequency. A touch switch for a door opening/closing device, which is equipped with a discriminator that discriminates a change in the oscillation frequency of an oscillator, and detects a person's contact with the antenna based on the output of the discriminator, the discriminator being a one-phase detector, A touch switch for a door opening/closing device, which is constituted by a phase synchronized circuit including a low-pass filter and a voltage or current controlled oscillator, and uses an oscillation frequency signal of the frequency oscillator as an input signal of the phase detector.