JPS6223272Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a power supply device using an inverter transformer, and is particularly designed to reduce the capacity of its power switch.

Prior to explaining the power supply device according to the present invention, a conventional device of this type will first be explained with reference to FIG. In the figure, 1 is a DC power supply, 2 is an inverter transformer, and 2a, 2b, and 2c are primary, secondary, and tertiary coils, respectively. The tertiary coil 2c is also called a feedback coil. 3 is an oscillation transistor, 4 is a starting resistor, and 5 is a capacitor, which in the illustrated example constitutes a so-called blocking oscillation circuit. 6 is a load connected to the secondary 2b. In such a power supply device, as shown in the figure, a switch 7 is connected to the output side of the power supply 1 to turn the power supply device on and off. Since the power switch 7 is directly connected to the output side of the DC power supply in this way, all of the current supplied from the power supply 1 flows to the switch 7, so that the switch 7 should have a relatively large capacity. Must be used. In the example of FIG. 1, the switch 7 is a so-called mechanical electric switch, but instead of this, the collector base of a transistor (not shown) may be connected and a DC voltage may be supplied to the base of the transistor from an external circuit. It is conceivable that this transistor could be operated in the same way as switch 7 by blocking it, but even in this case, it would be necessary to use a transistor with a large capacity.

In view of these points, the present invention is designed to use a switch with a smaller capacity and to perform the same operation as in the case of FIG. 1.

In explaining the apparatus according to the present invention with reference to FIG. 2, parts corresponding to those in FIG.

That is, in the present invention, the collector-emitter of the transistor 8 is inserted between the connection point P between the starting resistor 4 and the capacitor 5 and the base of the transistor 3, and the diode 9 is further connected between the collector-emitter. Therefore, transistor 8
A parallel circuit is constructed. In this case, the current flow direction in the diode 9 is selected to be opposite to the base-emitter current direction of the transistor 8. 10 is a control circuit for this transistor 8.

In this configuration, when the circuit 10 supplies a signal (current) that passes between the base and emitter of the transistor 8, the transistor 8 is turned on, and the power supply 1 supplies the starting resistor 4 and the collector of the transistor 8. A current is supplied to the base-emitter of the transistor 3 through the emitter, so that it is in an oscillating (operating) state and an output is supplied to the load 6. When the control circuit 10 cuts off the current to the base of the transistor 8, the transistor 8 is turned off, and the current passing between the base and emitter of the oscillation transistor 3 is cut off, and the above-mentioned oscillation operation is stopped. Therefore, no output is supplied to the load 6. Note that the diode 9 supplies a feedback current (alternating current) to the transistor 3 during the above-mentioned oscillation state.
This is to allow current to flow in the opposite direction of the current, and to allow blocking oscillation to occur normally.

According to the present invention explained above, the transistor 8
is connected between the base of transistor 3 and the connection point P, the current flowing here is only a very small current for transistor 3 to provide for blocking oscillation, and therefore transistor 8 can be used with a small capacitance. It has the characteristic of being able to use things. Moreover, by turning on or off this transistor 8, the entire device shown in FIG. 2 can be turned on and off in the same way as in the case shown in FIG. 1, so a small capacity switch is sufficient.

[Brief explanation of the drawing]

Figure 1 is a connection diagram showing an example of a conventional power supply device.
FIG. 2 is a connection diagram showing an example of the power supply device according to the present invention. 1 is a DC power supply, 2 is an inverter transformer, 4 is a starting resistor, 6 is a load, 8 is a transistor, 9 is a diode, and 10 is a control circuit.

Claims (1)

[Scope of utility model registration request] In a power supply device in which a transistor constituting an oscillation circuit is inserted between a DC power source and a primary coil of an inverter transformer, a starting resistor for the oscillating transistor and a capacitor connected to a feedback coil of the inverter transformer are provided. A power supply device characterized in that a parallel circuit consisting of a switching transistor and a diode is inserted between the connection point and the base of the oscillation transistor.