JPS6211102Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to stabilization of the bias power supply of the horizontal oscillation circuit of a television receiver.

In conventional television receivers, especially those operated using battery power, the horizontal oscillation frequency may shift due to fluctuations in the power supply. That is, the base bias of the horizontal oscillation transistor is obtained by applying the +B voltage obtained from the power supply circuit together with the horizontal AFC output through a resistor. Therefore, when the voltage of the battery power source drops and the voltage falls outside the control range of the stabilizing operation of the power supply circuit, +B decreases.
This causes the horizontal oscillation frequency to shift toward the lower side.

The present invention has been proposed in order to alleviate the above-mentioned problems, and allows the television receiver to continue operating for a while even if the power supply circuit goes out of control. Therefore, in the present invention, a negative DC voltage is obtained using a horizontal flyback pulse, and a stable bias voltage with little fluctuation is synthesized from this voltage and the +B voltage obtained from the power supply circuit. Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block circuit diagram showing a portion of a horizontal deflection circuit of a television receiver according to an embodiment of the present invention. Reference numeral 1 denotes an input terminal to which a horizontal synchronization signal separated from the composite video signal by a synchronization separation circuit is applied. 2 is a horizontal AFC circuit, the output of which is applied to a horizontal oscillation transistor 31 of a horizontal oscillation circuit 3. The output pulses of horizontal oscillation circuit 3 are applied to horizontal drive and horizontal output circuit 4. The output side of the horizontal output circuit 4 is connected to a series circuit of an S-shaped correction capacitor 5 and a horizontal deflection coil 6 so that a deflection current is supplied. 7 is a flyback transformer, to which a horizontal flyback pulse is applied to its primary winding 71, one end of which is connected to a parallel circuit of a damper diode 8 and a capacitor 9, and the other end of which is supplied to a horizontal output transistor. A DC voltage source is provided. The secondary winding 72 of the transformer 7 boosts the flyback pulse to the rectifier 1.
0, and its rectified output is applied as high voltage to the anode of the cathode ray tube. The output pulse of the circuit 4 is also transformed into a sawtooth wave by the integrating circuit 11, and is applied to the horizontal AFC circuit 2 for phase comparison. The circuit configuration so far is a well-known connection arrangement.

In the circuit arrangement shown in FIG. 1, the base bias voltage of the horizontal oscillation transistor 31 is set by the resistor 2
A +B voltage is applied from the power supply circuit via pins 0 and 21, and in addition to this, a negative DC voltage is applied as follows. A negative horizontal flyback pulse a from the secondary winding 73 of the flyback transformer 7
is taken out. This pulse a is transmitted through diode 2
2. It is converted into a negative DC voltage by a rectifying and smoothing circuit having a well-known connection consisting of a capacitor 23 and a resistor 24. This negative DC voltage is applied to resistors 20, 2
At connection point b of 1, the positive DC voltage is added to the +B voltage, resulting in a positive DC voltage selected to a predetermined value. This combined voltage is applied to the base of the horizontal oscillation transistor 31 together with the output of the horizontal AFC circuit 2.

Here, if the voltage of the power supply circuit decreases, the peak value of the flyback pulse a also decreases accordingly. Therefore, the absolute value of the negative DC voltage of the rectifying and smoothing circuit becomes small, and the combined bias voltage is kept constant because it cancels out. As a result, it is possible to prevent the frequency of the oscillation circuit from decreasing due to a decrease in the power supply voltage.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing a portion of a horizontal deflection circuit of a television receiver according to an embodiment of the present invention. 3...Horizontal oscillation circuit, 73...Winding of flyback transformer, 22-24...Rectification smoothing circuit, 2
0 and 21...Synthesis circuit.

Claims (1)

[Scope of utility model registration request] In the horizontal oscillation circuit of a television receiver, where a positive DC voltage is applied from the power supply circuit as the base bias of the horizontal oscillation transistor along with the horizontal AFC output, the winding installed in the flyback transformer extracts the negative horizontal flyback pulse. and,
A rectifying and smoothing circuit that obtains a negative DC voltage from this negative horizontal flyback pulse, and a synthesis circuit that adds the positive DC voltage and the negative DC voltage to form a base bias of the horizontal oscillation transistor. A bias power supply stabilizing device for horizontal oscillation circuits featuring: