JPS59138031A - Drive circuit for relay - 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] Technical field The present invention relates to a relay drive circuit.

In order to accurately control the switching behavior of prior art relays,
It is necessary to supply an accurate value of excitation current to the relay coil, and also to suppress the abnormally high back electromotive force that occurs during demagnetization.

Purpose The purpose of the present invention is to operate a relay accurately, and
An object of the present invention is to provide a relay drive circuit that suppresses the generation of abnormally high back electromotive force.

Embodiment FIG. 1 is an electrical circuit diagram of an embodiment of the present invention. This drive circuit controls a so-called bistable relay l. In this bistable relay 1, when current flows through the relay coil 2 in the direction of the arrow 3, the relay switch 4 becomes conductive in one switching mode, for example, and thereafter, even when the excitation current disappears, the switching mode of the relay switch 4 remains unchanged. Retained.

Further, when a current flows through the relay coil 2 in the opposite direction of the arrow 3, the relay switch 4 shuts off the other switching mode, for example, and thereafter maintains that switching mode even if there is no excitation current. There are 5 relay drive power supplies, all of which are DC power supplies. An excitation current is supplied from this power source 5 to the relay coil 2 in the direction of arrow 3 or in the opposite direction via a line 6, a constant current circuit 7, and four switching circuits 8 to 11 connected in a bridge. . A relay coil 2 is connected between opposing connection points 12 and 13 of the switching circuits 8 to 110. Switching circuits 8 to 11
The remaining opposing connection points 14.15 are .

It is connected to the constant current circuit 7 and the power supply 5, respectively.

A first diode 16 is connected to the constant current circuit 7 in parallel and with opposite polarity. Second diodes 17 to 2o are connected to each switching circuit 8 to 11 in parallel and with opposite polarity, respectively.

The control circuit 21 is connected in association with the switching circuits 8 to 11, and when a pair of switching circuits 8.9 facing each other becomes conductive, the remaining pair of switching circuits 10.11 are cut off.

At this time, an exciting current flows through the relay coil 2 in the direction of the arrow 3. On the contrary, a pair of switching circuits 10
．． 11 is conductive, and the remaining pair of switching circuits 8 and 9
When the relay coil 2VCid is cut off, the relay coil 2VCid arrow 3
Excitation current flows in the opposite direction. In this way relay 1
The switching mode of the relay switch 4 can be changed.

When an excitation current is flowing through the relay coil 2 in the direction of arrow 3, a back electromotive force is generated in the relay coil 2 when the excitation current disappears. This back electromotive force is transmitted from the connection point 12 to the second diode 17. Connection point 14, first diode 1
6. Line 6, power supply 5, connection point 15. It flows through the closed loop formed via the diode 18 and the connection point 13. Therefore, the back electromotive force is prevented from increasing beyond the voltage E of the power supply 5. In this way, abnormal high voltage is not generated when the relay coil 2 is demagnetized.

In the constant current circuit 7, the light emitting diode 23 of the photocoupler 22 is driven to turn on as shown at t1+ in Figure 2. Therefore, the phototransistor 24Fi becomes conductive every time light is received. When the phototransistor 24 becomes conductive,
Transistor 25 shuts off. This causes transistor 26 to shut off and transistor 27 to conduct. Resistors R1, R2, R3, R4 and a diode 28 are connected to the transistor 27. The current flowing between the emitter and the collector of the transistor 27 is determined by a constant value directly depending on the resistance of the resistor R3.

Photocoupler 29 included in switching circuit 8.9
．． The light emitting elements 31 and 32 of 30 are driven to light up as shown in FIG. 2(2). Switching circuit 10.11
A light emitting element 35. of the photocoupler 33.34 included in the photocoupler 33.34.
36 is driven to turn on as shown in FIG. 2(3). The current flowing through the relay coil 2 is as shown in FIG. 2(4)K. Photocoupler 2 of switching circuit 8
When the light emitting element 31 included in 9 lights up, the phototransistor 36 becomes conductive. This allows transistor 3
7 conducts, so that transistor 38 conducts.

This causes transistor 39 to become conductive. Further, in the switching circuit 9, the light emitting element 3 of the photocoupler 3o
2 lights up, the transistor 41 becomes conductive. This causes transistors 42 and 43 to conduct. In this way, an excitation current flows in the direction of arrow 3 through transistors 39 and 43. This excitation current is limited to one constant current by the constant current circuit 7. Light emitting element 2
When 3, 31, and 32 go out, it becomes relay coil 2! ! The generated back electromotive force is transferred to the diode 17°16 as mentioned above.
, flows through the power supply 5 and the electric current 18. Therefore, the back electromotive force never exceeds the voltage E of the power supply 5.

Light emitting element 35.3 included in photocoupler 33.34
When 6 is lit, transistors 45 and 46 become conductive. This causes transistors 47 and 48 to become conductive, and transistors 49, 50 and 51 to become conductive. In this way, a constant excitation current determined by the constant current circuit 7 flows through the relay coil 2 in the opposite direction of the arrow 3 through the transistors 50 and 51.

When the light emitting elements 35 and 36 are turned off, the back electromotive force induced in the relay coil 2 flows through the diode 19.16% power supply 5 and the diode 20. As a result, the back electromotive force increases the voltage E of the power supply 5.

It will never be surpassed.

Constant current circuit 7 is energized by power supply 53.

The switching circuit 8.10 is also energized by the power supply 54. The switching circuit 9.11 is powered by the power supply 55.

In order to improve the responsiveness of the relay 1, the voltage of the power source 5 may be increased, or alternatively, the excitation current determined by the constant current circuit 7 may be increased.

As another embodiment of the present invention, a relay driving power source 5, a constant current circuit 7, a switching circuit 8 or 9, and a relay coil 2 of a relay 1 are connected in series to form a closed loop, and a first The diode 16 and the second diode 17, 18 corresponding to the switching circuit 8 or 9 may be connected with opposite polarity. Such modifications are also included within the spirit of the invention.

The relay l may have a configuration in which the switching mode changes only during the period when the relay coil 2 is excited,
It may have other configurations. The present invention can also be used to test the characteristics of relays.

Effects As described above, according to the present invention, the excitation current of the relay can be supplied at a reliable value by the constant current circuit, and the generation of abnormal back electromotive force can be suppressed. The switching mode can be changed accurately.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram of an embodiment of the present invention; FIG. 2 is a waveform diagram for explaining the operation of the embodiment shown in FIG. 1; FIG. 1...Relay, 2...Relay coil, 5...1)
Ray J1 toy power supply, 7...constant current circuit, 8-11.
...Switching circuit% 16...First diode, 1
7-20...Second diode, 21...Control circuit agent Patent attorney Kei Nishi - Yoshishi

Claims (1)

[Claims] f+) A power supply for driving a relay, and a constant current circuit connected in series with the power supply for driving a relay. A switching circuit connected in series to the relay drive power supply, constant current circuit, and relay coil. A first diode connected in parallel to the constant current circuit and with opposite polarity, and a second diode connected in parallel with the switching circuit and with opposite polarity.
A relay drive circuit that includes a diode. (2) Four of the switching circuits are provided and connected in a bridge manner, and the relay coil is connected between the opposing connection points of these switching circuits, and the remaining opposing connection points of the switching circuits are used for driving the relay. A patent claim characterized in that a pair of switching circuits that are connected in series to a power supply and a constant current circuit, and that face each other are made conductive, and at this time, the remaining pair of switching circuits are controlled to be cut off. A drive circuit for the relay according to item 1.