JPS6041372A - Power supply device of television receiver - Google Patents

Abstract

PURPOSE:To improve the efficiency of the whole of a device and prevent the influence of a switching noise by multiplying the frequency of a fly-back pulse to switch a switching element with a multiplied frequency of a horizontal frequency. CONSTITUTION:The fly-back pulse is taken out from a horizontal deflecting circuit 1 of a TV receiver and the frequency is multiplied in a multiplying circuit 2 to a frequency which is a number of times as high as the horizontal frequency. This obtained signal is differentiated by a differentiation circuit 3 to obtain a trigger signal having a narrow pulse width. This trigger signal is applied to an oscillating circuit 4 to obtain a pulse oscillation output which has an integer-fold frequency of the horizontal frequency and is synchronized with the fly-back pulse. This output is applied to a pulse width modulating circuit 5 to control the pulse width and is amplified by an amplifying circuit 6 and is applied to a switching element to switch this element 7. Then, a pulse having an optional magnitude is obtained from a transformer 8 and is rectified and smoothed by means 9 and 10 and is supplied to a load circuit 11. Meanwhile, its DC voltage is detected by an error circuit 12; and if it is deviated from a desired voltage, the width of the output pulse in the circuit 5 is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a switching regulator type power supply device used in a television receiver. is often used. However, this type of power supply circuit has the disadvantage of generating a lot of switching noise, and in order to prevent this noise from appearing on the screen, the switching signal was synchronized with the flybank pulse. It was designed to perform horizontal frequency switching. In this way, the influence of switching noise can be reduced by providing a horizontal frequency filter circuit (trap circuit).

However, such conventional devices have the disadvantage that the conversion efficiency of the transformer is poor due to the low switching frequency, and the efficiency is not very good.

Furthermore, if the switching frequency is increased in an attempt to improve efficiency, the stability of the oscillation frequency of the switching signal becomes extremely poor, and the frequency changes significantly due to fluctuations in load current, making it difficult for filter circuits to remove switching noise. There is a problem that the ``mud'' does not work well and noise appears on the screen.

SUMMARY OF THE INVENTION An object of the present invention is to provide a power supply device for a television receiver that eliminates such conventional drawbacks, and one embodiment thereof will be described below with reference to the drawings.

In the figure, 1 is the horizontal deflection circuit of the television receiver, from which the flyback pulse is extracted, and the multiplier circuit 2
The frequency is multiplied by multiple times (2 to 5 times the horizontal frequency) the horizontal frequency. As the multiplier means, it is preferable to use, for example, a tank circuit as shown in FIG. 2, which consists of a koinol 2L and a capacitor 2C tuned to a frequency multiple times the horizontal frequency. Then, the obtained signal is differentiated by a differentiating circuit 3 to obtain a trigger signal with a narrow pulse width. This differentiating circuit 3 may also include a capacitor 3C and a resistor 3R as shown in FIG. Then, the trigger signal is added to an oscillation circuit 4 such as an unstable multi-pipe rake that oscillates pulses at a frequency that is approximately multiple times the horizontal frequency, and the oscillation operation is triggered to generate a pulse at a frequency that is an integer multiple of the horizontal frequency. Obtain stable pulse oscillation output synchronized with bank pulse. After this is added to the pulse width modulation circuit 5 to control the pulse width, it is amplified by the amplifier circuit 6, and is added to the switching element 7 for switching. Then, a pulse of an arbitrary magnitude is obtained from a transformer 8 connected between the switching element 7 and the power supply terminal, which is rectified and smoothed by a diode 9 and a capacitor 10, and then supplied to the load circuit 11 as a DC power source. do. On the other hand, the error detection circuit 12 detects whether the magnitude of the DC power supply deviates from the desired voltage, and if there is a deviation, the width of the output pulse in the pulse width modulation circuit 5 is controlled to control the DC power supply voltage. Control is performed so that the magnitude is always constant at the desired voltage.

In this way, this device multiplies the flyback pulse and switches the switching element at a frequency multiple times the horizontal frequency, which greatly improves the conversion efficiency in the transformer and greatly improves the overall efficiency. It is something that can be done. Moreover, since the switching signal is synchronized with the multiplied signal of the flyback pulse, it is extremely stable, and the frequency of the switching noise generated is also stable, so its influence can be easily reduced with a filter circuit, etc. It is also easy to prevent noise from appearing on the screen.

As described in detail above, according to the present invention, it is possible to obtain a power supply device for a television receiver that is highly efficient and less affected by the adverse effects of switching noise.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a power supply device for a television receiver according to an embodiment of the present invention, and FIG. 2 is a specific circuit diagram of a part thereof. 1... Horizontal deflection circuit, G... Multiplier circuit, 3...
...Differentiating circuit, 4...Oscillation circuit, 5...Pulse width modulation 1 path, End...Switching element, 8.
・River Lance, 9...Diode, 10...
・Capacitor, 11...;...Load circuit, 12 ・
・Error detection circuit.

Claims (1)

[Claims] The flybank pulse obtained from the horizontal deflection circuit is multiplied to produce a signal with multiple times the horizontal frequency, and this signal triggers the oscillation circuit to output a pulse oscillation at multiple times the horizontal frequency in synchronization with the flyback pulse. This pulse m is generated and the switching element is switched by the output signal controlled by the pulse width modulation circuit, and the pulse output generated in the transformer connected to this switching element is rectified and smoothed to supply DC power to the load circuit. A power supply device for a television receiver, wherein the pulse width modulation circuit is controlled by a signal that detects the magnitude of the output DC power supply to stabilize the magnitude thereof.