JPS5924214Y2 - television receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a television receiver equipped with a self-oscillation type switching regulator type power supply circuit.

FIG. 1 is a circuit diagram showing the main parts of a television receiver equipped with a conventional self-oscillation type switching regulator type power supply circuit.

The self-oscillating switching regulator type power supply circuit shown in Figure 1 is a DC-D converter using a blocking oscillation circuit.
This is a known technology in which a constant voltage control circuit 17 is provided in a C converter.

The constant voltage control circuit 17 detects fluctuations in the DC voltage obtained at the output terminal A, and controls the switching time of the switching transistor 12 so as to suppress this fluctuation.

The output terminal B has the tertiary winding 2 of the flyback transformer 21.
A voltage is obtained by converting the flyback pulse generated at 2 into a direct current, and the overvoltage protection circuit 23 stops voltage generation when this voltage rises abnormally.

Resistors 24, 25 and Zener diode 26 constitute a voltage detection circuit, and cynostar 28 is connected between output terminal A and ground.

When the DC voltage at output terminal B exceeds a specified value, thyristor 28 turns on, short-circuits output terminal A, reduces the output voltage to zero, and loads circuit 18 consisting of horizontal output circuit 20, audio circuit, etc. protect

At this time, the DC voltage generated at the output terminal C also becomes approximately zero, and the horizontal oscillation/drive circuit 19 also stops operating.

In FIG. 1, when the tertiary winding 8 or the diode 13 of the converter transformer 5 is disconnected, no DC voltage is output to the output terminal A, and the constant voltage control circuit 17 does not function. The generated DC voltage rises above the specified value.

Since conventional circuits do not provide any protection against such a phenomenon, components of the horizontal oscillation/drive circuit 18 are selected so that they will not be destroyed even by the increased voltage.

However, since there is no protection against the above phenomenon, the conventional circuit lacks safety and the components selected above are expensive.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide an inexpensive and highly reliable television receiver.

In order to achieve the above object, the present invention connects a switch that is turned on when high voltage abnormally rises to an output terminal and a reference potential terminal where an output voltage is generated for which fluctuations are not detected by the constant voltage control circuit of a switching regulator. In addition, the switch is turned on even when the output terminal rises abnormally.

The present invention will be explained below with reference to FIG.

FIG. 2 is a circuit diagram showing an embodiment of the present invention.

In FIG. 2, the same parts as in FIG. 1 are designated by the same reference numerals.

In FIG. 2, a diode 29 is provided and the thyristor 28 is connected to the output terminal C.

When the transformer tertiary winding 8 or the diode 13 has an open failure, the increased output voltage generated at the output terminal C is transmitted to the output terminal B through the diode 29, so the overvoltage protection circuit 23 is activated and the output terminal C is grounded. Short circuit.

Also, the DC voltage at output terminal B increases and the thyristor 28
When the output terminal C is turned on and the output terminal C is connected to ground, the horizontal oscillation/drive circuit 19 stops operating, so the horizontal output circuit 20 also stops operating, and high voltage generation is also stopped.

As described above, the overvoltage protection circuit 23 can be operated to prevent the output voltage of the output terminal C from rising when the tertiary winding 8 or the diode 13 of the converter transformer 5 has an open failure. The horizontal oscillation/drive circuit 19 can be protected.

Note that in the event of an open failure in the diode 15 or the quaternary winding 9 of the converter transformer 5, the output voltage at the output terminal A does not rise due to the control action of the constant voltage control circuit 17.

In the figure, 1 is an AC power supply, 2 is a diode, and 3 is an AC power supply.
, 14 and 16 are capacitors, 6 and 7 are primary and secondary windings of the converter transformer 5, and 30 is a picture tube.

As described above, the horizontal oscillation/drive circuit 1 is
It is possible to reduce the cost and improve the safety of No. 9 parts.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing a conventional television receiver, Figure 2 is a circuit diagram showing a conventional television receiver.
The figure is a circuit diagram showing an embodiment of a television receiver according to the present invention. 5: Converter transformer, 8: Tertiary winding, 9: Quaternary winding, 13, 15, 29: Diode, 19: Horizontal oscillation
Drive circuit, 20: Horizontal output circuit, 23: Overvoltage protection circuit, 28: Cyrisk.

Claims (1)

[Scope of utility model registration request] A switching regulator includes a transformer having a first output terminal and a second output terminal, and operates to detect fluctuations in a first output voltage generated at the first output terminal and suppress the fluctuations; a horizontal output stage that is operated by an output voltage of and generates a high voltage; a drive stage that is operated by a second output voltage that is generated at a second output terminal and drives the horizontal output stage; For the drive stage to operate, flat light 1. and a stop means for turning on the switch and stopping the operation of the drive stage when at least one of the high voltage and the second output voltage exceeds a predetermined value. A television receiver comprising: