JPS598978B2 - Dengen Cairo - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power supply circuit using silicon-controlled rectifying elements used in television receivers and the like.

Conventionally, this type of power supply circuit normally connects an AC power input terminal 1 to a DC power input terminal 8 via a rectifying and smoothing circuit T consisting of four diodes 2, 3, 4, 5 and a capacitor 6, as shown in FIG. Derive the uncontrolled DC input voltage B, and apply this DC input voltage B to the primary winding 10 of the choke transformer 9.
, is supplied to the anode of the silicon-controlled rectifier 13 via the tertiary winding 12 of the horizontal output transformer 11, and supplies the DC output voltage B2 derived to the cathode of the silicon-controlled rectifier 13 to the horizontal output circuit 14. There is.

Here, the horizontal output circuit 14 includes, in addition to the horizontal output transformer 11, a horizontal output transistor 15, a damper diode 16, a resonance capacitor IT), a diode 18 for absorbing abnormal pulses, a resistor 19, a capacitor 20, a horizontal deflection coil 21, and a It is composed of a character correction capacitor 22.

Further, the DC power input terminal 8 is connected to the starting pulse supply circuit 26 of the silicon-controlled rectifier 13, which is formed by connecting a diode 25 in series with the capacitor 23 and grounding it in the opposite direction, and connecting a reverse current blocking diode 24 to the connection point. The gate electrode 27 is connected to a cathode via a resistor 28, and the cathode, ie, the power output terminal 29, is grounded via a capacitor 30.

Further, the power input terminal 8 is connected to a power output terminal 29 via a resistor 31, and the choke transformer 9 has two
One end of the next winding 32 is grounded via a diode 33,
The other end is connected to the power supply output terminal 29, and the DC output voltage B2 derived to the power supply output terminal 29 is stepped down and stabilized by a resistor 34, a constant voltage diode 35, and a capacitor 36, and then output from the power supply terminal 3T to the error detection phase. The output pulse of the phase control circuit 38 is supplied to the gate electrode 27 of the rectifying element 13 via the capacitor 41. In the constant voltage power supply circuit configured as described above, the power switch 39 is closed and the rectifying and smoothing circuit T.
When supplying input AC voltage to the power supply input terminal 8
A rectified and smoothed uncontrolled DC voltage is derived, and this uncontrolled DC voltage is applied to the primary winding 10 of the choke transformer 9,
Controlled through the tertiary winding 12 of the horizontal output transformer 11 and the silicon-controlled rectifier 13, a stabilized DC output voltage B2 is derived from the power supply output terminal 29, and the DC output voltage B is the horizontal output voltage. The signal is supplied to the circuit 14, and after being stepped down through the resistor 34, it is also supplied to the error detection phase control circuit 38 from the power supply terminal 37.

When the power switch 39 is turned on now, the starting pulse supply circuit 26 is activated and a starting pulse is supplied to the gate electrode 27 of the silicon-controlled rectifying element 13. As a result, the silicon-controlled rectifying element 13 is triggered and turned on, and the winding 10 of the power supply input terminal 8 is connected to the winding 10 of the transformer 9.
The capacitor 30 is charged via the tertiary winding 12 of the horizontal output transformer 11. When the capacitor 30 is charged to a certain voltage, the horizontal output circuit 14 starts the horizontal deflection operation and the error detection phase control circuit 38 also starts the horizontal deflection operation. The operation also starts, and thereafter the silicon-controlled rectifier 13 is turned on by the output pulse obtained from the tertiary winding 12 of the horizontal output transformer 11 and the output pulse (turn-off pulse) obtained from the error detection phase control circuit 38. - It is controlled to be off, and thus the voltage stabilization operation of the DC output voltage B is performed.

That is, the error detection phase control circuit 38
In this circuit, the phase of the turn-off pulse of A starting pulse supply circuit 26 consisting of a capacitor 23 and diodes 24 and 25 is provided between the rectifying and smoothing circuit 7 and the gate electrode 27 of the control rectifying element 13.
The power switch 39 is turned on and the charging current of the capacitor 23 is applied as a starting pulse to the gate electrode 27 of the control rectifier 13, turning on the control rectifier 13 and supplying the starting voltage to the horizontal output circuit 14, etc. In this case, Voltage value of DC input voltage B of DC power supply input terminal 8, capacitor 23
Charging time constant of capacitor 2 when power switch 39 is turned on.
The operating period of this circuit is determined by the minimum trigger current value of the charge control rectifier 13 stored in the capacitor 23, and when the charging current of the capacitor 23 exceeds the gate trigger current of the control rectifier 13, the rectifier 13 It is turned on.

However, in this type of conventional circuit, when the power supply voltage B1 applied to the AC power input terminal 8 becomes higher than the rated value, a starting pulse is supplied to the gate electrode 27 of the control rectifier 13 after the power switch 39 is turned on. The charging current of the capacitor 23 of the circuit 26 increases, and the output voltage obtained through the control rectifier 13 may become temporarily high, and the charging current of the capacitor 23 is used to turn on the control rectifier 13. When the power supply voltage is gradually increased from O to the rated voltage value, there are disadvantages such as the charging current of the capacitor 23 does not reach the gate trigger current value of the control rectifier 13 and the control rectifier 13 cannot be turned on. Ta.

The present invention has been made in view of the above-mentioned drawbacks.
An embodiment thereof will be explained with reference to the drawings. In other words, the present invention provides a bidirectional varistor 40 between the DC power input terminal 8 at the output end of the rectifying and smoothing circuit 7 and the gate electrode 27 of the silicon-controlled rectifying element 13 as shown in FIG. Connect the bidirectional varistor 40
This constitutes the pulse supply circuit 26.

The bidirectional varistor 40 used in the present invention has a voltage-current characteristic that rises sharply with the rising voltage E1 (-E,), as shown in FIG. 3, for example. Since the present invention is configured as described above, when the power switch 39 is turned on, the DC input voltage B1 is derived from the DC power input terminal 8 via the rectifying and smoothing circuit 7, and the DC output is derived from the cathode of the silicon-controlled rectifying element 13. Assuming that the voltage is B, and the rising voltage of the bidirectional varistor 40 is E1, if B, -B,>E, the bidirectional varistor 40 becomes conductive and the starting pulse supply circuit 26 operates, and the silicon Control rectifier 1
A current flows through the gate electrode 27 of No. 3, turns on the silicon-controlled rectifying element 13, and the DC output voltage B rises to a certain voltage value, starting the horizontal output circuit 14, the word difference detection phase control circuit 38, etc. A horizontal retrace pulse is superimposed on the anode of the silicon-controlled rectifying element 13 from the tertiary winding 12 of the horizontal output transformer 11, and this superimposed pulse voltage causes the DC input voltage B to become the <DC output voltage B. Even in this case, the bidirectional varistor 40 connects the gate electrode 27 of the silicon-controlled rectifier 13 to the DC power input terminal 8.
Since no current flows towards the reverse current blocking diode 24
becomes unnecessary.

In this way, since the starting pulse supply circuit of the present invention utilizes the rising voltage of the bidirectional varistor, it is not subject to power supply voltage restrictions, which was a drawback of conventional capacitor charging currents, and when the power supply voltage is high. However, even if the voltage rises gradually, everything is controlled by the rising voltage of the bidirectional varistor, so a good starting pulse supply operation is always performed.
The horizontal output circuit can be activated reliably and stably.

Furthermore, the circuit configuration of the starting pulse supply circuit can be made extremely simple and inexpensive.

[Brief explanation of the drawings] Fig. 1 is a conventional circuit diagram, Fig. 2 is a circuit diagram of the present invention, and Fig. 3 is a conventional circuit diagram.
The figure is a voltage-current characteristic diagram of a bidirectional varistor used in the present invention, where 8 is a DC power input terminal, 13 is a silicon-controlled rectifier, 26 is a starting pulse supply circuit, 27 is a gate electrode, and 40 is a bidirectional varistor. gender barista, respectively.

Claims (1)

[Claims] 1. A power supply circuit for a television receiver that controls on/off a silicon-controlled rectifying element based on horizontal pulses obtained from a horizontal output transformer and output pulses obtained from an error detection phase control circuit to obtain a stabilized DC output voltage. A starting pulse supply circuit made of a bidirectional varistor is connected between the DC power input terminal and the gate electrode of the silicon-controlled rectifier, and a starting pulse is applied to the gate electrode of the silicon-controlled rectifier through the starting pulse supply circuit. A power supply circuit configured to supply power.