JPS603675Y2 - power supply - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a switching regulator type power supply device, and allows the use of small-capacity switching elements for opening and closing the power supply device.

A conventional power supply device of this type is shown in FIG.

In the figure, 1 is an AC power supply, 2 is a power switch, 3 is a rectifier diode, 4 is a starting transistor, 5 and 6 are its bias resistors, 7 is a control transistor, 8 is its base resistor, 9
is a Zener diode, 10 is a charging capacitor, 11
is an oscillation circuit, 12 is a drive circuit, 13 is an output transistor, 14 is an output transformer, 15 is a rectifier diode, 1
6 is a load, and 17 is a rectifier diode having a backflow prevention function.

Its operation will be briefly explained.

Now, when the switch 2 is closed, the AC power supply voltage is rectified by the rectifier diode 3 to become a DC voltage, and the output voltage
4 to the collector of the output transistor 13.

On the other hand, the starting transistor 4 also becomes conductive and a DC voltage is generated at its emitter, causing the oscillation circuit 11 and the drive circuit 12 to become conductive.
is applied to

As a result, the oscillation circuit 11 and the drive circuit 12 operate, the output transistor 13 becomes conductive, and the output transistor 14 becomes conductive.
, a load 16 operates via a rectifier diode 15.

Further, the output of the rectifier diode 15 is also applied to the oscillation circuit 11 and the drive circuit 12 via the diode 17.

On the other hand, the output of the starting transistor 4 is charged to the capacitor 10 via the Zener diode 9 and the base resistor 8, and when the potential across the capacitor 10 rises, the base potential of the control transistor 7 also rises, and the control transistor 7 is conductive.

When the control transistor 7 becomes conductive, a collector current flows and the base potential of the starting transistor 4 decreases, so that the starting transistor 4 is finally cut off.

However, at this time, voltage has already been applied to the oscillation circuit 11 and the drive circuit 12 by the rectifier diode 17, so they continue to operate as a power supply circuit.

However, in the above-described conventional configuration, a large current flows through the switch 2, so if an electronic switch is used as the switch 2, a large-capacity transistor is required, and the auxiliary circuit for controlling this becomes complex, resulting in increased cost. The disadvantage was that it was expensive.

The present invention eliminates the above-mentioned conventional drawbacks.

An example of this will be described below with reference to FIG.

In the figure, elements having the same functions as those in FIG. 1 are denoted by the same numbers, and explanations thereof will be omitted.

In FIG. 2, the switch 2 in FIG. 1 is removed and a transistor 18 is provided, and the emitter of the transistor 18 is connected to a forward voltage protection diode 19 and a reverse current prevention diode 2.
0 to one end of the resistor 6, and the collector to the resistor 21
It is connected to the base of an oscillation transistor (not shown) in the oscillation circuit 11 via a resistor 22, and the base is connected to the emitter of the starting transistor 4 via a resistor 22.

Then, a switch 23 is inserted between the connection point between the diode 19 and the diode 20, the base of the starting transistor 4, and the collector of the control transistor 7.

24 is a charging capacitor inserted into the base of the transistor 18.

Next, its operation will be explained.

Now, when contacts A and B of the switch 23 are momentarily short-circuited, the starting transistor 4 becomes conductive, and the oscillation circuit 11 and drive circuit 12 start operating as described above.
A power supply voltage is supplied to the load 16 .

When the transistor 7 becomes conductive after a certain period of time has elapsed, the starting transistor 4 is cut off.

At this time, the power supply voltage is supplied from the rectifier diode 17 to the oscillation circuit 11 and the drive circuit 12 as described above.

On the other hand, voltage is also supplied to the base of the transistor 18 from the rectifier diode 17, and when the capacitor 24 is charged, the transistor 18 becomes conductive.

However, in this case, the contacts A and B of the switch 23 are already open, and in other words, by making the time constant of the resistor 22 and capacitor 24 relatively long, the transistor 18 becomes conductive before the switch 23 is opened. By setting it so that it does not occur, contacts A and B are open, and the diode 20 is in the opposite direction, so
The collector current of transistor 18 does not flow, and the power supply circuit continues to operate.

Next time, when you want to stop the operation of the power supply, switch 2 again.
3, contacts A and B are momentarily short-circuited.

In this case, since the control transistor 7 is already conductive and the transistor 18 is also kept conductive, the collector current of the transistor 18 flows to the ground via the diode 19 and the contacts A and B transistor 7. As a result, the operation of the oscillation circuit 11 is stopped, and all the circuits after the drive circuit 12 are also stopped, and the power supply device becomes inactive.

Furthermore, when operating the power supply device again, it is sufficient to momentarily short-circuit contacts A and B in the same way.

As explained above, according to the present invention, by providing the switch circuit in the base circuit of the starting transistor, when using a transistor in the switch circuit, it is possible to use a transistor with a small current capacity, which reduces cost. You can get a cheap power supply.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional power supply device, and FIG. 2 is a circuit diagram of a power supply device according to an embodiment of the present invention. 1... AC power supply, 3, 15... Rectifier diode, 4... Starting transistor, 7...
... Control transistor, 〒 ... Zener diode, 10゜24 ... Charging capacitor, 11 ... Oscillation circuit, 12 ... Drive circuit , 13... Output transistor, 14...
...Output Lance, 16...Load, 18.
...Transistor, 23...Switch.

Claims (1)

[Scope of utility model registration request] a DC power supply circuit, an oscillation circuit, an output circuit that generates a DC voltage and supplies it to a load when an oscillation output from the oscillation circuit connected to the DC power supply circuit is supplied, and a DC output of the output circuit; a first diode connected between the output side of the output circuit and the oscillation circuit so as to supply the voltage also to the oscillation circuit; a starting transistor whose collector and emitter are connected in series between the DC power supply circuit and the oscillation circuit; and a control transistor whose collector and emitter are connected between the base of the starting transistor and ground. Then, a certain period of time after the voltage at the interconnection point connected between the oscillation circuit, the first diode, and the starting transistor and the base of the control transistor increases, a resistor and a capacitor that conduct the control transistor and cut off the starting transistor; a stopping transistor whose collector is connected to the oscillation control portion of the oscillation circuit; and a stopping transistor having the same polarity as the stopping transistor. a second connected in series with the emitter of the transistor;
a third diode having a polarity opposite to that of the second diode and connected between the second diode and the DC power supply circuit, and an interconnection point between the second and third diodes; a switch connected between the base of the starting transistor, an interconnection point between the oscillation circuit, the first diode, the starting transistor, and the base of the stopping transistor; A power supply device comprising a resistor and a capacitor that raise the voltage to a point at which the base of the stop transistor becomes conductive after a certain period of time after the voltage at the connection point increases.