JPH02244532A - Relay driving device - Google Patents

Abstract

PURPOSE:To lessen heat emission from the coil of a relay and suppress also the output current of a DC power supply by connecting a parallel circuitry of a resistance and capacitor with the emitter of a transistor, connecting a constant voltage element with the other end of this parallel circuitry and the base of transistor, and by driving the relay by the collector of transistor. CONSTITUTION:When a control circuit 7 gives an On signal to a resistance 6, a transistor 4 is turned on, and the output voltage of a DC power supply 2 is impressed on the two ends of relay 3. When a capacitor 10 is charged, a certain current flows through the coil of this relay 3 regardless of the coil resistance. therein the capacitor of this capacitor is set so that its charging time becomes longer than the relay operation time, and the voltage of a constant voltage element 12 and the resistance value of resistance 11 are set so that a holding current to allow holding of the relay 3 after actuation will flow through the coil of the relay 3, and thereby the current flowing through the coil of the relay 3 can be suppressed to the minimum because only the holding current flows through the coil of the relay 3 after its actuation.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a relay drive device.

2. Description of the Related Art A conventional relay drive device has a configuration as shown in FIG. That is, 1 is an AC power supply, 2 is a DC power supply composed of a transformer 2a, a rectifier stack 2b, and a capacitor 2C, 3 is a relay, and 4 is a transistor that controls the relay 3.
6, 6 is a resistor, 7 is a control circuit that outputs an on/off signal,
8 is a load circuit constituted by an electronic circuit (for example, an LED display circuit), and 9 is a constant voltage power supply serving as a power source for the control circuit 7 and the load circuit 8, and is constituted by a transistor 9a, a resistor 9b, and a constant voltage diode 9C. When the control circuit 7 outputs an on signal to the base of the transistor 4 via the resistor 6, the transistor 4 turns on and drives the relay 3.

Problems to be Solved by the Invention However, in such a conventional configuration, the AC power supply 1
Due to voltage fluctuations in the load circuit 8 and current fluctuations in the load circuit 8, the DC power supply 2
The output voltage of relay 3 fluctuates, while the voltage applied to relay 3 fluctuates by the change in coil resistance of relay 3 (relay 3 operates when the amperage of the coil reaches a constant value, so the current remains constant, and the current changes as the coil resistance changes). (The amount of change is the change in the impressed voltage), so depending on the temperature characteristics of the coil resistance, it will vary from -10℃ to
In the range of +116℃, it is about 0.9 to 1.
Changes by 4 times. Furthermore, if we take into account the variation in coil resistance (±10 degrees), the voltage applied to relay 3 will vary by a factor of 8 to 1.5, which means that the coil resistance of relay 3 is approximately 1.5 times that of 20°C. Furthermore, if the output voltage of the DC power supply 2 is set to a voltage that allows the relay 3 to operate even when the voltage of the AC power supply 1 is low and the current of the load circuit 9 is large, the coil resistance of the relay 3 will be approximately 0.8. When the voltage of the AC power supply 1 is high, the voltage applied to the relay 3 becomes high, and the temperature of the relay 3 becomes high. Since the output current of transformer 2a is large,
There are issues such as the need for a large capacity transformer.

It is an object of the present invention to solve these problems and provide a two-way relay drive device.

Means for Solving the Problems In order to solve the above problems, the relay drive device of the present invention connects a parallel circuit of a resistor and a capacitor to the emitter of a transistor, and connects the other end of this parallel 1.1l=1 path to the transistor. A constant voltage element is connected to the base of the transistor, and the collector of this transistor drives the relay.

Operation Since the relay drive device of the present invention has the above configuration and 17, the output voltage of the DC power source is applied to the relay coil for a predetermined time in the trench where the relay operates, but after the relay operates, the transistor is applied with a constant current. A constant current is applied to the relay regardless of the relay's coil resistance value, so even if the output voltage of the DC power supply changes, a constant current flows through the relay, which reduces heat generation in the relay coil and transforms the relay. The output current of the device may also be small.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIG. In Figure 1, 10 is a capacitor, 11 is a resistor, 1
2 is a constant voltage element, and the other configuration is the same as the second example shown in the conventional example.
The configuration is the same as that in the figure, and the same numbers are given.

Next, the operation of the configuration of the above embodiment will be explained.

The voltage between the base and emitter of transistor 4 is ■BE,
The resistance value of the resistor 11 is R11, and the voltage of the constant voltage element 12 is V.
z, when the control circuit 7 outputs an on signal to the resistor 6, the transistor 4 is turned on, and the output voltage of the DC power supply 2 is applied to both ends of the relay 3. On the other hand, capacitor 10
When charged, the resistance 11Kid(VZ-vBE)/R1
Assuming that 107L5ft is iXh and hFE of the transistor 4 is sufficiently large, a current of (Z-vBE)/R11 flows through the coil 12 of the relay 3 regardless of the coil resistance. Here, the capacitor 46 of the capacitor 10 is set such that the charging time of the capacitor 10 is longer than the operating time of the relay 3.
is set, and the constant current H element/
If the voltage vZ of 12 and the resistance value R11 of the resistor 11 are set, after the relay 3 operates, only a holding current (generally about a fraction of the moving current) flows through the coil of the relay 3. The current flowing through the coil can be minimized. In addition, if the capacity of the condenser 2C is set so that the current until the relay 3 operates can be supplied from the capacitor 2C of the DC power supply 2, the current capacity of the transformer FM2a can be further reduced.

Effects of the Invention As is clear from the description of the above embodiments, the present invention allows only the current required to maintain the relay to flow through the relay coil after the relay operates, so that voltage fluctuations of the AC power supply and load circuit Even if the output voltage of the DC power supply fluctuates due to current fluctuations, or the relay coil resistance changes due to temperature changes or variations, a constant current always flows through the relay coil.
Since the coil of the relay generates little heat and the output current of the DC power supply is also low, the transformer can be made smaller and lower in cost.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a relay driving device showing an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional relay driving device.

Claims (1)

[Claims] Connect one end of the relay to the collector of the transistor, connect one end of the parallel circuit of a resistor and capacitor to the emitter of the transistor, connect the other end of the relay and the other end of the parallel circuit of resistor and capacitor to a DC power supply, and connect the resistor and capacitor to the emitter of the transistor. A relay drive device configured by connecting a constant voltage element to the other end of a parallel circuit of a capacitor and the base of a transistor, and connecting a control circuit that outputs an on/off signal to the base of the transistor via a resistor.