JP2536145B2 - AC 2-wire solid state switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an AC two-wire non-contact type in which a series circuit of an AC power supply and a load is opened and closed by a sensor circuit such as a proximity switch driven by the AC power supply. Regarding switches.

[Conventional technology]

When the switching signal such as thyristor is controlled by the detection signal of the sensor circuit to open and close the series circuit of the AC power supply connected to the outside and the load, the sensor circuit power supply is not an independent power supply but is supplied from the AC power supply. In this way, the power to the load can be controlled by the switching element simply by connecting the output terminal between both ends of the series circuit of the general commercial power source and the load. FIG. 3 is a wiring diagram of such an AC two-wire type non-contact switch filed by the applicant (Japanese Patent Application No. 63-331674). In FIG. 3, an AC power supply 1 and a load 2 are connected in series and connected between output terminals T ₁ and T ₂ .
The AC terminal of the single-phase bridge rectifier circuit 3 is connected between the terminals T ₁ and T ₂ . A main thyristor 4 is connected between the DC output terminals of the bridge rectifier circuit 3 (hereinafter, this DC output terminal is abbreviated as a power supply terminal), and a constant voltage circuit 5, a sensor circuit 6, a capacitor 7, a gate circuit 8, etc. In the constant voltage circuit 5, a series circuit of a zener diode 9 and a resistor 10 is connected to the power supply ± ends, and this connection point is a transistor.
It is connected to 11 bases. And switching transistor
The sensor circuit 6 is supplied with power via 12 collectors and emitters, and is connected so as to charge the capacitor 7. The base of this transistor 12 is a resistor connected to the power supply ±
It is connected to the connection point of the series circuit of 13 and the collector / emitter of the output transistor 6a, and the detection signal of the sensor circuit 6 turns on the output transistor 6a and turns off the transistor 12. The charging thyristor 14 is connected in series with the sensor circuit 6 and is connected to the power supply ± terminal, and the gate thereof has both transistors 11,1.
Connected to 2 connection points. The gate circuit 8 of the main thyristor 4 comprises a zener diode 15, a resistor 16, and a capacitor 17 connected in parallel with the resistor 16, and one end of the capacitor 17 is connected to the gate of the main thyristor 4.

The transistor 11 is on when a voltage is generated at the power supply terminal. When the sensor circuit 6 does not detect the phenomenon and the output transistor 6a is off, a voltage is applied to the base of the switching transistor 12 and the transistor 12 is turned on. Then, power is supplied to the sensor circuit 6 and the capacitor 7 is charged. At this time, since the voltage across the sensor circuit 6 is set lower than the zener voltage of the zener diode 15, the zener diode 15 does not conduct and the main thyristor 4 is off. When the sensor circuit 6 detects a phenomenon, the output transistor 6a turns on, the transistor 12 turns off, and the charging thyristor 14 turns on. That is, the power supply to the sensor circuit 6 is switched from the transistor 12 to the charging thyristor 14. At this time, the Zener diode 15 becomes conductive, so the main thyristor 4
Turns on, and a current flows through the load 2. At this time, the voltage at the power supply ± ends drops to almost 0, but the sensor circuit 6
Of the main thyristor 4 turned on by continuing the detection operation with the discharge current of
Turns off at every 0th point of the power supply frequency current, but this has no effect.

When the amplification factor of the transistor 11 that constitutes the constant voltage circuit 5 is high, if a resistor 18 is connected in series to the collector of the transistor 11 as shown by the broken line, the capacitor 7 becomes sharp when the power supply 1 is turned on. It is possible to prevent the load 2 from malfunctioning due to the charging current flowing therethrough.

[Problems to be Solved by the Invention]

In the circuit shown in FIG. 3, when the output transistor 6a of the sensor circuit 6 is turned off, the output voltage of the constant voltage circuit 5, that is, the voltage V _Z1 of the Zener diode 9 to the base-emitter voltage V _BE of the transistor 11 and the transistor 12 of the transistor 12. The voltage V _Z1 −V _BE −V _CE minus the collector-emitter voltage V _CE is lower than the sum of the Zener voltage V _Z2 of the Zener diode 15 and the gate voltage V _g1 of the main thyristor 4 (V _Z2 + V _g1 ). I have to. When the output transistor 6a is on, the output voltage of the constant voltage circuit 5 varies from the voltage V _Z1 of the Zener diode 9 to the base / emitter voltage V _{BE of the} transistor 11 and the thyristor 1.
The voltage _Z1 −V _BE −V _g2 minus the gate voltage V _g2 of 4 must be lower than the voltage plus the sum of V _Z2 and V _g2 (V _Z2 + V _g2 ). That is, there must be a relationship of voltage V _g2 >> voltage V _CE . Under these conditions, it is desirable to select the characteristics of the components with some margin due to their variations, but the output transistor 6a turns on, the transistor 12 turns off, and the thyristor 14
When is turned on, the capacitor 7 is charged until the thyristor 4 is turned on, that is, the voltage of the capacitor 7 reaches the voltage V _Z2 + V _g1 . After that, the thyristor 4 is once turned off about every half cycle, but if the voltage of the capacitor 7 is higher than the output voltage V _Z1 −V _BE −V _{g2 of the} constant voltage circuit 5 at this time, the thyristor 14 is turned on without the gate current flowing. It becomes impossible. In order for the thyristor 14 to turn on, the voltage of the capacitor 7 is the voltage while the thyristor 4 is on.
It must be lower than V _Z1 -V _BE -V _g2 , and in order to do so, the relationship between the capacitance of the capacitor 7 and the impedance of the sensor circuit 6 must be fully considered. Therefore, in this circuit, not only the accuracy of the voltage of each part but also the capacity of the capacitor and the impedance of the sensor circuit are accurate, and the characteristics of the semiconductor are greatly influenced by the temperature, so that the temperature must be stable. .

An object of the present invention is to provide an AC two-wire non-contact switch that is not affected by the accuracy of the voltage of each part of the circuit, the capacity of the capacitor, the accuracy of the impedance of the sensor circuit, and the temperature.

[Means for solving the problem]

The present invention, in order to solve the above problems, a rectifier circuit in which a series circuit of an AC power supply and a load is connected between both input terminals,
A main thyristor connected between both output terminals of the rectifier circuit, and a sensor circuit having an output transistor whose emitter is connected to the gate of the main thyristor and detecting a predetermined phenomenon and sending a detection signal to the output transistor. A capacitor connected in parallel with the sensor circuit, a constant voltage circuit connected between both output terminals of the rectifier circuit, a gate connected to the emitter of a transistor of the constant voltage circuit and connected in series with the sensor circuit. Charging thyristor, a switching transistor connected between the charging thyristor, a gate and a cathode, a Zener diode connected between the base of the switching transistor and the collector of the output transistor, and a base-emitter of the switching transistor. And a diode connected between them.

[Action]

The switching transistor is turned off by turning on the output transistor of the sensor circuit, and the current flowing from the output of the constant voltage circuit to the sensor circuit is passed to the gate of the charging thyristor to make the charging thyristor conductive and the voltage across the sensor circuit is detected by the zener diode. Then, a current is caused to flow through the gate of the main thyristor via the output transistor to make the main thyristor conductive. Even if the main thyristor is turned off by setting the Zener diode in series with this output transistor to a value lower than the output voltage of the constant voltage circuit, while the output transistor is on, the transistor of the constant voltage circuit immediately changes the charging thyristor. A current is sent to the output transistor through the gate / cathode, diode, and Zener diode,
The main thyristor is quickly turned on without being affected by the accuracy of the voltage of each part, the impedance of the sensor circuit, and temperature changes, and the capacitor connected in parallel with the sensor circuit is charged rapidly to the voltage of the Zener diode. In this way it is also possible to accelerate the operation of this switch and reduce its voltage drop.

〔Example〕

1 and 2 show an embodiment of the present invention, in which the same parts as those in FIG. 3 are designated by the same reference numerals as those in FIG. In FIG. 1, an AC power supply 1 and a load 2 are connected in series as usual, and are connected between terminals T ₁ and T ₂ . The AC terminal of the single-phase bridge rectifier circuit 3 is connected between the terminals T ₁ and T ₂ .
In addition, main thyristor 4, constant voltage circuit 5, output transistor
Since the sensor circuit 6, the capacitor 7 and the like except 6a are completely the same as the conventional ones, the description thereof will be omitted. This switch differs from the conventional one in that the output transistor 6a of the sensor circuit 6 is connected in series with the resistor 13 and the gate / cathode of the main transistor 4, and is connected to the power supply terminal. Further, a series circuit of the charging thyristor 14 and the sensor circuit 6 is connected to the power supply terminal. And a gate circuit 8 consisting of a resistor 16 and a capacitor 17 between the gate and cathode of the main thyristor 4.
Is connected. A switching transistor 12 whose collector is connected to the emitter of the transistor 11 is connected between the gate and cathode of the thyristor 14, and a Zener diode 19 is connected between the base of the transistor 12 and the collector of the output transistor 6a. The diode 20 is connected in antiparallel between the emitters.

With such a configuration, when the sensor circuit 6 does not detect a phenomenon, the output transistor 6a is off, the transistor 12 is on, and both thyristors 4 and 14 are off. Further, when the output transistor 6a turns on, the base current of the transistor 12 does not flow, so that the transistor 12 turns off, the output current of the constant voltage circuit 5 flows to the gate of the thyristor 14, and the thyristor 14 turns on. When the output transistor 6a is turned on, the base and emitter of the transistor 12 are reversely biased, but the diode 20, Zener diode 19, output transistor 6a
Since a current flows through the gate of the main thyristor 4 via the, the main thyristor 4 is turned on, and while the main thyristor 4 is on, the sensor circuit 6 operates stably by the electric charge of the capacitor 7. Once turned on, the main thyristor 4 turns off at the current 0 point in each half cycle of the frequency of the power supply 1, but at that time, the voltage across the sensor circuit 6, that is, the voltage across the capacitor 7 is 0 at the sensor circuit 6. Also, the voltage V _{d of the} diode 20 and the zener voltage of the zener diode 19
V _Z3 is the sum of the voltage V _O of the output transistor 6a and the gate voltage V _g1 of the main thyristor 4, and the output voltage of the constant voltage circuit 5 is higher than the above sum voltage (V _d + V _Z3 + V _O + V _g1 ). If set, the current naturally flows from the constant voltage circuit 5 to the gate of the charging thyristor 14, the thyristor 14 is turned on, the capacitor 7 is instantly charged, and the main thyristor 4 is turned on again when it rises from 0 point.

FIG. 2 shows an embodiment different from FIG. This circuit is different from Fig. 1 in that the Zener diode 19 and the diode are
20 is omitted and the Zener diode 19 is short-circuited.

The operation of this circuit is such that when the output transistor 6a turns on, the base current of the transistor 12 does not flow, so that the output current of the constant voltage circuit 5 flows to the gate of the thyristor 14 and the thyristor 14 turns on. When the output transistor 6a is turned on, the base and emitter of the transistor 12 are reversely biased, but the emitter and base of the transistor normally have a Zener effect of about 6V. Similarly to the Zener diode 19 shown, a gate current is supplied to the main thyristor 4 via the emitter / base of the transistor 12 and the output transistor 6a to turn on the main thyristor 4. Then, while the main thyristor 4 is on, the sensor circuit 6 operates stably by the discharge current of the capacitor 7. The other operations are the same as those in FIG.

〔The invention's effect〕

The gate current for conducting the main thyristor flows by detecting the voltage across the sensor circuit with the Zener diode, and sometimes with the emitter-base voltage of the switching transistor, and by setting this voltage lower than the voltage of the constant voltage circuit. It is possible to instantly conduct the switch every half cycle, and reduce the voltage drop during the switch operation. By inserting a Zener diode between the base of the switching transistor and the collector of the output transistor, the relationship between the output voltage of the low-voltage circuit and the voltage level across the sensor circuit can be made arbitrary, facilitating component selection, The effect is that it is not affected by temperature. In addition, the gate current for conducting the charging thyristor is
Since the current consumed by the sensor circuit is switched and supplied by the switching transistor, the circuit for supplying the gate current to the charging thyristor is not required. Further, since the switching transistor does not require a high breakdown voltage and the current capacity may be small, there is an effect that the switching transistor has a simple circuit configuration and is inexpensive.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 show an embodiment of an AC two-wire type contactless switch according to the present invention, FIG. 1 is a connection diagram showing one embodiment, and FIG. 2 is FIG. 3 is a connection diagram showing an embodiment different from
FIG. 1 is a connection diagram showing an example of a conventional AC two-wire non-contact switch. 1: AC power supply, 2: Load, 3: Rectifier circuit, 4: Main thyristor, 5:
Constant voltage circuit, 6: sensor circuit, 6a: output transistor, 7:
Capacitor, 12: switching transistor, 14: charging thyristor, 19: Zener diode, 20: diode.

Claims (1)

(57) [Claims] 1. A rectifier circuit in which a series circuit of an AC power source and a load is connected between both input terminals, a main thyristor connected between both output terminals of the rectifier circuit, and an emitter at the gate of the main thyristor. A sensor circuit having a connected output transistor for detecting a predetermined phenomenon and sending a detection signal to the output transistor, a capacitor connected in parallel with the sensor circuit, and a capacitor circuit connected between both output terminals of the rectifier circuit. A constant voltage circuit, a charging thyristor having a gate connected to the emitter of a transistor of the constant voltage circuit and connected in series with the sensor circuit, and a switching transistor connected between the gate and the cathode of the charging thyristor, A Zener diode connected to the base of the switching transistor and the collector of the output transistor, and a base of the switching transistor. And exchange 2 wire proximity switch, characterized by comprising a diode connected between the emitter.