JPS6034293B2 - Automatic reset type switch circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic return type switch circuit that can be used for automatic opening/closing doors.

Incidentally, in an oscillation type proximity switch for an automatic door opening/closing door, the oscillation output decreases when a human body or the like approaches, so this is detected and a signal to start opening/closing the door is output.

FIG. 1 shows an example of such a switch circuit (for example, Tsubaki Kaisho No. 50-126151).
When the potential of T is lower than V by △V, that is, the output S
W Kagigame A. When amplified by , its duration t is t=
C. -Tesen...'11.

However, Ao is the open loop gain of the operational amplifier 1. In this way, the duration t is affected by the leakage current of the capacitor C and the leakage current of the operational amplifier 1, and in practice, the leakage current of the operational amplifier 1 is especially large, so the duration t becomes difficult. However, in a buried type proximity switch, when the sensing part is deeply buried, the amount of change from the sensing part is small, so if the ratio of the amount of the amplifier is made large, the above problem becomes more noticeable. As a switch circuit to solve this problem, as shown in Fig. 2, a voltage follower with high input impedance consisting of an operational amplifier 2 is inserted into the negative input terminal of the operational amplifier 1, and the voltage across the capacitor C is held for a long time. There is something I did.

However, in this switch circuit, if the detection signal DT from the sensing plate gradually changes due to external noise such as temperature, the change will be shorter than the duration time constant C-T, and sometimes it will malfunction. To prevent this, a capacitor C. A variable resistor R3 is connected in parallel with the resistor R3 to minimize the necessary duration time constant to prevent the above-mentioned special effects.However, in order to maintain the voltage, the resistor R3 must be made as large as possible, This creates a contradiction in that the resistance R3 must be made smaller in order to follow changes. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an automatic reset type switch circuit which is free from the above-mentioned drawbacks and problems. This invention will be explained below.

The present invention relates to an automatic return type switch circuit used in an automatic opening/closing door, and as shown in FIG. A voltage follower 11 inputs the output S, and feeds it back to the other terminal (1) via a resistor R, o, a filter 12 for removing high frequency components of the detection signal DT, and an output of this filter 12. DTA to variable resistor VR.

The signal S2 whose gain was adjusted by and the output S of the operational amplifier 10
, and outputs a binary signal S3; a switching circuit 15 that amplifies the output S3 of the operational amplifier 13 to operate the IJ relay 14 as an automatic door control circuit; A transistor Q as a switching element whose on/off is controlled by an inverted signal S3 from an inverter NT of an output S3, a delay circuit 16 that delays the output S3 of the operational amplifier 13, and an output S4 of this delay circuit 16 connected to a variable resistor. VR,. A comparator 17 that outputs a binary signal S5 by comparing it with a reference voltage Ke formed by Resistors R, 5 and R, 7 are connected to the respective collectors of the voltage follower 11, and are also connected to the input of the voltage follower 11. Thus, the operational amplifier 1 is connected to feedback resistors R and 2, and the voltage follower 11 is connected to diodes D and 2 for reverse current blocking.
. , an operational amplifier 18 whose negative input terminal is directly connected and fed back, and a resistor R, 8 and a capacitor C, which are connected to the positive input terminal. It consists of Further, the filter 12 is connected to resistors R, . and capacitor C, . The switching circuit 15 consists of a resistor R,3 and a transistor Q3, and the relay 14 includes surge absorbing diodes D, . are connected in parallel. Furthermore, the transistor Q. Resistors R, 4 and R, 6 are inserted into the bases of Q3 and Q3, and the delay circuit 1
Reference numeral 6 is composed of a variable resistor VR,2, a diode D,2 connected in parallel to the variable resistor VR,2, and a capacitor C,2 connected between the connection point thereof and the power supply -Vc. Note that a switch button PB for circuit reset and a resistor R for adjusting a time constant are connected in parallel to the capacitors C and O of the voltage follower 11. In such a configuration, the switch circuit functions as a DC amplifier when the detection signal DT is (V, 1△V), and charges the capacitor C, o with an amplification factor of 1 when the detection signal DT is (V, 1△V). becomes.

Now, when the detection signal DT is V in a steady state, the output S of the operational amplifier 10 is SI=V. -Thatching-A.

...[21], which is input to the negative input terminal of the operational amplifier 13. However, in equation {2), n is the open loop gain of the operational amplifier 10. The positive input terminal of the operational amplifier 13 is connected to the detection signal DT (V,
) passes through filter 2 and then variable resistor VR,. Since the voltage is stepped down and inputted, the output S3 of the operational amplifier 13 is a binary "L". Therefore, the switching circuit 15
The transistor Q is turned off, and the relay 14 is cut off. Further, since the output S3 is inverted by the inverter NT, its output level 63 is "H", and the transistor Q becomes normal. This causes capacitor C,. Since the resistor R, 5 is inserted in parallel with the above-mentioned, there is no possibility of malfunction due to the gradual signal change. In addition, in the case of the Kinki switch for automatic doors, the resistance R, 5 as a leak resistance should be set to be longer than the speed (time) of a person approaching the sensing plate under the floor, and with such a time constant. By doing so, it is possible to sufficiently follow signal changes based on external temperature, etc., and the above-mentioned malfunctions can be eliminated. When a person approaches the sensing plate, the detection signal DT changes from V to (V, 1△V), and the output S of the operational amplifier 10 changes to S. =(v′△v)・Shadow・A.

...(3', and this is input to the negative input terminal of the operational amplifier 13, and the detection signal DT(V, -△V
) is divided by the variable resistor VR,o and input to its positive input terminal. Thus, since S2>S, the output S3 of the operational amplifier 13 becomes binary "H", the transistor Q3 is turned on, and the relay 14 is operated.
At this time, the output S3 of the inverter NT becomes ``L'', so the transistor Q. is turned off, and the insertion of the resistors R and 5 is cut off, so that it can be held for a long time.
In this case, the output S5 of the comparator 17 is a binary "L", and the transistor Q2 is off. Furthermore, if there are no resistors R and 8 connected in series to the capacitors C and o, the relationship between the detection signal DT and the output size 6 will be A resogging phenomenon may occur. However, when the resistors R and 8 are inserted as in the present invention, a delay is provided to the voltage of the capacitors C and o, which serve as the reference voltage of the negative input terminal of the operational amplifier 10, so that the change in the detection signal DT is Its output S. does not cause any ringing phenomenon. Here, if the holding time is too long, the door may remain open if rain or the like falls on the sensing slope.

Therefore, in the present invention, a delay circuit 16 is provided, and the output S3
When a predetermined time (for example, 1 minute) has elapsed after C. A resistor R, 7 is inserted in parallel with o. That is, when the output S3 becomes "H", the capacitor C,2 is gradually charged via the variable resistor VR,2, and this is input to the positive input terminal of the comparator 17, and the capacitor C,2 is charged through the variable resistor VR,2. It is compared with the reference voltage Re adjusted by . Then, when S4≧Re, the output of the comparator 17 becomes a binary "H", and the transistor Q2 turns on, so that the resistor R, 7 is connected to the capacitor C, and so on. It is inserted in parallel with. Thus, resistor R,7 becomes capacitor C,
. When inserted as a leakage resistor, the output S3 of the operational amplifier 13 becomes "L", the 1' relay 14 is also restored, and the transistor Q2 is also turned off, and as mentioned above, the transistor Q is turned on and the resistor R is , 5 is capacitor C
, o in parallel. Note that the recovery time is determined by the VR. of the delay circuit 16. It can be arbitrarily adjusted by changing the time constant of 2·C,2 or the reference voltage Re. Also,
If the return time is long, it is necessary to wait until the return time during maintenance or adjustment, which causes inconvenience, but in this case, it is sufficient to press the external operation switch button PB attached to the voltage follower 11. This allows for instantaneous recovery, which is very convenient for maintenance and the like. As described above, according to the switch circuit of the present invention, by inserting the resistor R, 5 as a leak resistance during steady state, it is possible to prevent malfunctions due to gradual signal changes, and when the switch is operating, it is possible to prevent the malfunctions from occurring automatically after the set time has elapsed. It has the advantage of being able to be restored.

Note that a timer or the like may be used as the delay circuit in the above-described embodiment, and other switching elements such as thyristors may be used in place of the transistors Q, -Q.

Also, capacitor C, in FIG. performs integration, and can be replaced by a Miller integrator using an operational amplifier.

[Brief explanation of the drawing]

FIGS. 1 and 2 are circuit configuration diagrams showing conventional switch circuits, respectively, and FIG. 3 is a circuit configuration diagram showing an embodiment of the present invention. 1, 2, 10, 13, 18... operational amplifier, 1
1... Voltage follower, 12... Filter follower,
14... Relay, 15... Switching circuit, 16... Delay circuit, 17...
Comparator, Q, ~Q3...Transistor, NT.
...in/data. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A first terminal for inputting a detection signal from a sensing plate to one terminal.
an operational amplifier; a voltage follower that inputs the output of the first operational amplifier and feeds it back to the other terminal; and a filter for removing high frequency components of the detection signal.
A second operational amplifier inputs the output of this filter and the output of the first operational amplifier and outputs a binary signal, and the output of the second operational amplifier is amplified to operate an automatic door control circuit. a switching circuit; a first switching element that is turned on and off by an inverted signal of the output of the second operational amplifier; a delay circuit that delays the output of the second operational amplifier; It comprises a comparator that outputs a binary signal in comparison with a reference voltage, and a second switching element that is turned on and off by the output of the comparator, and the first and second switching elements are connected to the voltage follower. An automatic return type switch circuit characterized in that it is connected to the input of the switch circuit. 2. The automatic reset type switch circuit according to claim 1, wherein the voltage follower includes a reset switch circuit.