JPH05145391A - Solid-state relay - Google Patents

Abstract

PURPOSE:To improve the safety by providing 1st and 2nd input side circuits and output side circuits to the relay activating other output circuit on the condition that either of the 1st and 2nd output side circuits is not activated. CONSTITUTION:With a switch SW closed, a photodiode PD 2 in a normally-on operation circuit 1 is lighted and a photo transistor(TR) PT2 is turned on, a PD 4 goes off and the PT4 is turned off. On the other hand, a PD1 is lighted in a normally-off operation circuit 2 and a voltage E is impressed between points e, f of the input circuit 1. With the SW opened, the PD4 of the circuit 1 is lighted, the PT4 is turned on and the voltage E is impressed between points g, h of the input circuit 2. The PD3 of the circuit 2 is lighted, the PT3 is turned on to goes off the PD1 and the PT1 is turned off and no voltage is impressed on the input circuit 1. With the switch turned on, a voltage is impressed on the input circuit 1 and no voltage is impressed on the input circuit 2. Thus, simultaneous conduction of the output side circuits is avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state relay, and more particularly to a C-contact type solid-state relay for controlling the states to be in conflict with each other.

[0002]

2. Description of the Related Art Conventionally, this type of solid-state relay uses two solid-state relays and is switched by a mechanical switch.

[0003]

In the above prior art, since two solid state relays are used,
There are drawbacks in that it is expensive in terms of configuration, and that it requires many man-hours including wiring work for mechanical switches and the like. There is also a drawback that both circuits are turned on at the same time due to malfunction or failure of the triac, leading to a serious accident. Further, there is a problem that switching sound is generated due to switching of contact points, and the use range is limited. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a solid state relay which prevents serious accidents and has high safety.

[0004]

In order to achieve the above object, a solid state relay according to the present invention has a photocoupler arranged between an input side circuit and an output side circuit, and turns on a triac by the output of the photocoupler. In the solid state relay, first and second input side circuits and output side circuits are provided, respectively, between the first input side circuit and the second output side circuit, between the second input side circuit, and the first output side. Photocouplers are respectively provided between the circuits, and the other output side circuit is made conductive on condition that one of the first and second output side circuits is not conductive.

[0005]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 shows an embodiment of a solid state relay of the present invention, which has a terminal 1 for voltage application for driving an input side circuit, a terminal 2 for inputting a circuit switching signal and a GND terminal 3 and responds to the circuit switching signal. And a normal-on operation type circuit 1 and a normal-off operation type circuit 2 which operate in a reciprocal manner. Further, the rectifier circuit 1 is the output circuit 1
Is connected in parallel with the terminal 1 of the input circuit 2 via the photocoupler PHC4. On the input side of the solid state relay, a driving DC power source E is connected between terminals 1-3, a pull-up resistor RP is connected between terminals 1-2, and an operation switching switch SW is connected between terminals 2-3. .. On the other hand, loads A and B and an AC power source e are connected to the output side.

The input circuit 1 includes resistors R1, R2, R
3, R4, R5 and transistors Q1, Q2, phototransistor PT1 of photocoupler PHC1 and photocoupler P
Input circuit 2 consisting of photodiode PD2 of HC2
Is composed of resistors R9, R10, R11, R12, R13, transistors Q3, Q4, Q5, a phototransistor PT4 of the photocoupler PHC4, and a photodiode PD3 of the photocoupler PHC3. The output circuits 1 and 2 include phototransistors PT2 and PT3 of the photocouplers PHC2 and 3, drive circuits and triacs TR1 and TR2, and resistors and capacitors R6, C11 and R1 that form a snubber circuit.
4 and C3. The rectifier circuits 1 and 2 include current limiting resistors R7, R8, R15, R16 and a full-wave rectifying diode.
Bridge DB1, DB2, capacitor C to smooth it
2, C4, photocouplers PHC4, and photodiodes PD4, PD1 of PHC1.

Next, the operation of the solid state relay having the above-mentioned structure when the loads A and B are switched will be described with reference to the timing chart. In the circuit, the transistor Q1 of the normally-on operation circuit 1 is off when the switch SW is on. At this time, photo coupler P
Since the phototransistor PT1 of HC1 is in the ON state (described later), current flows from the power source E to the transistor Q2 through the resistors R3 and R4 to the base and the emitter, and the transistor Q2 is turned on. Therefore, the photo coupler PH
The photodiode PD2 of C2 emits light, the phototransistor PT2 is turned on, and the triac TR1 is turned on via the drive circuit. Since no voltage is applied between a and b of the rectifier circuit 1, the photodiode PD4 of the photocoupler PHC4 is in the off state and the phototransistor PT4 is in the off state.

On the other hand, in the normally-off operation type circuit 2, since the phototransistor PT4 is in the off state, the photocoupler P
The photodiode PD3 of HC3 is off and is in an off state. At this time, the AC voltage e is applied between a and b of the rectifier circuit 2.
Is applied, the photodiode PD1 of the photocoupler PHC1 emits light. Therefore, the phototransistor P
T1 is in the ON state, and the voltage E is applied between e and f of the input circuit 1. Next, when the switch SW is turned off (FIG. 2A), in the normally-on operation type circuit 1, current flows from the DC power source E to the base and emitter of the transistor Q1 via the pull-up resistor RP and the resistor R1, and Q1 becomes It turns on. Therefore, the current does not flow to the base and emitter of the transistor Q2, and the transistor Q2 is turned off.
2 is turned off. Therefore, the normally-on operation type circuit 1 is turned off (FIG. 2A). Here, since the AC voltage e is applied between a and b of the rectifier circuit 1, the photodiode PD4 of the photocoupler PHC4 emits light and the phototransistor PT4 is turned on. Therefore, the DC voltage E is applied between g and h of the input circuit 2. (Fig. 2c)

In the normally-off operation type circuit 2, a current flows from the DC power source E through the pull-up resistor RP1 and the resistor R9 to the base and emitter of the transistor Q3, and is turned on. For this reason, no current flows through the base and emitter of the transistor Q4, and the transistor Q4 is turned off and the resistor R12
A current flows through the base and emitter of the transistor Q5 via the transistor Q5 to be turned on. Therefore, the photodiode PD3 of the photocoupler PHC3 emits light, and the phototransistor PT
3 is turned on. Therefore, the triac TR2 is turned on by the drive circuit. (FIG. 2D) At this time, since no voltage is applied between cd of the rectifier circuit 2, the photodiode PD1 is turned off and the phototransistor PT1 is turned off. Therefore, the input circuit 1
The voltage E is not applied between e and f. (FIG. 2E) Next, when the switch is turned on, the normally-on operation type circuit 1 at this point is not turned on because the phototransistor PT1 is in the off state. In the normally-off operation type circuit 2, the transistor Q3 is off, Q4 is on, and Q4 is on.
5, the phototransistor PT3 is also turned off, and the triac TR2 is turned off (FIG. 2C). Here, since the AC voltage e is applied between cd of the rectifier circuit 2, the photodiode PD1 emits light, the phototransistor PT1 is turned on, and the voltage E is applied between ef of the input circuit 3 (Fig. 2h).

In the normally-on operation type circuit 1, the transistor Q1 is turned off and the transistor Q2 is turned on.
1 is turned on (Fig. 2). Since no voltage is applied between a and b of the rectifier circuit 1, the photodiode PD4 is turned off and the phototransistor PT4 is turned off.
Therefore, the voltage E is not applied between g and h of the input circuit 2 (FIG. 2C). Thus, the outputs of the normally-on operation type circuit 1 and the normally-off operation type circuit 2 are applied to the output circuit after one of the output circuits is turned off. Then, since the other circuit is turned on by using the AC voltage, both circuits are not turned on at the same time. This can be dealt with not only in the case of normal operation, but also in the case of malfunction due to a failure of one of the output circuits.

[0011]

(1) According to the present invention, the first and second input side circuits and the output side circuit are respectively provided, and the first and second circuits are provided.
Photo couplers are provided between the input side circuit and the second output side circuit, between the second input side circuit, and between the first output side circuit, respectively.
Since the other output-side circuit is made conductive on condition that one of the first and second output-side circuits is not conductive, when either one of the triacs fails, the first and second The output side circuits do not conduct at the same time. Therefore, it is possible to prevent a serious accident such as burning of equipment and provide a highly safe solid state relay. (2) According to the present invention, the first and second input side circuits and the output side circuit are provided respectively, and the first input side circuit and the second output side circuit are connected and the second input side circuit is connected. Since a photocoupler is provided between the first output side circuits and the other output side circuit is made conductive on condition that one of the first and second output side circuits is not conductive, the operation switching is performed. Since there is always a fixed time difference, it is possible to reliably prevent damage and the like. (3) Since it is not necessary to use two solid state relays as in the conventional case, it is advantageous in terms of wiring work and price, and the wiring work is simplified and rational.

[0012]

[Brief description of drawings]

FIG. 1 is an embodiment of a solid relay of the present invention.

FIG. 2 is a timing chart of the present invention.

[Explanation of symbols]

 1, 2, 3, 4, 5, 6-terminal PHC1, PHC2, PHC3, PHC4 Photocoupler PT1, PT2, PT3, PT4 Phototransistor PD1, PD2, PD3, PD4 Photodiode TR1, TR2 Triac DB1, DB2 Full-wave rectification diode bridge A, B load

Claims (1)

[Claims] 1. A photocoupler is arranged between an input side circuit and an output side circuit, and a triac is turned on by the output of the photocoupler.
The first and second solid state relays with N
And a photocoupler between the first input side circuit and the second output side circuit, between the second input side circuit, and between the first output side circuit. A solid-state relay characterized in that one of the first and second output side circuits is made conductive, and the other output side circuit is made conductive.