JPH0488872A - Stabilizing power source circuit - Google Patents

Abstract

PURPOSE:To reduce the calorific value of an SCR and allow latitude in the selection of the element capacity by connecting plural switching elements (SCR) in parallel, and further providing control circuits, which control SCR's individually according to the change of load. CONSTITUTION:When an SCR 3 is turned on and started by a starting circuit 5, a capacitor 17 is charged by the output voltage from the cathode side, and the start-up stops, and also a horizontal output circuit 16 gets in operating condition, and generates a flyback pulse, and it is boosted by a flyback transformer 23. At this time, by the pulse from tertiary winding 27, gate control circuits 6 and 9 get in operating conditions, respectively, and also the capacitors 32 and 33 are charged. Therefore, the gate control circuit 9 instantaneously turns on the third transistor 41 by the negative electrode pulse, which is gotten from a differentiating circuit 39 by the second transistor 37 being turned on by the voltage that the output voltage from SCR3 is superposed through the first transistor 35, and outputs a control pulse. And the control pulse form this gate control circuit 9 is supplied to the gate of SCR 8, and it is turned on.

Description

[Detailed description of the invention] L Awagami Nisarasato! The present invention relates to a stabilized power supply circuit used for supplying driving DC voltage to, for example, a horizontal output circuit of a television receiver.

Traditionally, in television receivers, the DC voltage for driving the horizontal output circuit is supplied from a stabilized power supply circuit, and the voltage supplied to the horizontal output circuit is affected by fluctuations in the input power supply voltage and fluctuations in the high-voltage load current. I tried to prevent it from changing. Specifically, such a stabilized power supply circuit is configured as shown in Figure 4, where (1) is an input terminal to which an unstable DC voltage obtained by rectifying and smoothing a commercial AC voltage is supplied, and (2) is an input terminal as shown in Figure 4. A blanking period pulse of negative polarity is provided on the primary side of a flyback transformer that boosts and takes out a blanking period pulse from a horizontal output circuit (not shown). , that is, for turn-off), the pulse superimposition winding (3) repeats on and off, and is supplied from the input terminal (1) to its anode side via the pulse superimposition winding (2). This is a silicon-controlled rectifier (hereinafter referred to as rscRj) that intermittently outputs a DC voltage of from the cathode side, and the voltage output from the cathode side is
4) is supplied to the horizontal output circuit. (5) is a starting circuit that outputs a turn-on starting pulse to the gate of SCR (3) only when voltage supply starts, (6) is 5CR (3)
The gate control circuit (6) outputs a turn-on control pulse to the gate of the SCR (3), and the gate control circuit (6) controls the output timing of the control pulse according to the value of the output voltage output from the cathode side of the SCR (3). It is meant to be controlled.

Therefore, after activation, the SCR (3) is turned on during the horizontal scanning period by a control pulse supplied to its gate, and turned off during the retrace period by a negative retrace period pulse supplied to its anode side. The turn-on timing is controlled based on the value of the output voltage from the cathode side, which is likely to change depending on input voltage and load fluctuations. As a result, SCR(3
The voltage output from the cathode side of ) will supply a stabilized DC voltage.

However, in a stabilized power supply circuit with a conventional configuration like this,
As power consumption increases due to larger screens of television receivers,
Since the amount of heat generated by the SCR increases, it is necessary to take various measures to prevent heat dissipation, such as enlarging the heat sink.
The device capacitance was also limited to large ones.

The present invention has been made in view of these points, and is
It is an object of the present invention to provide a stabilized power supply circuit that reduces the amount of heat generated in a CR and allows a wide selection of element capacitances.

In order to achieve the above object, the present invention provides a stabilized power supply circuit that stabilizes an unstable DC voltage through a switching element that repeatedly turns on and off, and then supplies it to a load.
A plurality of the switching elements (in this case, 5CR) are connected in parallel, and a control circuit (in this case, a gate control circuit) is provided to individually control each SCR according to load fluctuations. be. Specifically, a DC voltage is supplied to the anode side of each SCR via a pulse superimposition winding that superimposes a turn-off pulse, and a DC voltage is supplied to the gate of each SCR according to the voltage output from the cathode side. A turn-on pulse is supplied from the gate control circuit at the same timing.

With this configuration, the amount of heat generated by each SCR is reduced by the number of SCRs, and furthermore, by controlling each SCR individually, the capacity of each element can be efficiently selected.

'LJL! 11 An embodiment of the present invention will be described below with reference to the drawings.

It should be noted that the same parts as those in the prior art will be given the same reference numerals and the explanation thereof will be omitted.

In this embodiment, as shown in FIG. 1, in addition to the combination of the above-mentioned pulse superimposition winding (2), SCR (3), and gate control circuit (6), one more stage of pulse superimposition winding (
7) and SCR (8) and its gate control circuit (9)
The combinations of are connected in parallel, and this added SCR (
8) is activated by the gate control circuit (9) when the SCR (3) is activated by the activation circuit (5) and generates an output voltage on its cathode side.

Therefore, after activation, the SCRs (3) and (8) are turned on during the horizontal scanning period by control pulses from the gate control circuits (6) and (9) supplied to their gates, respectively, and the SCRs (3) and (8) are turned on during the horizontal scanning period by the control pulses supplied to their gates, respectively. It is simultaneously turned off during the retrace period by a retrace period pulse of negative polarity, and the turn-on timing is controlled based on the value of the output voltage from the cathode side. As a result, S
The voltage output from the cathode side of CR (3) (8) is always kept constant except for the horizontal retrace period, regardless of input voltage or load fluctuations, and S CR (3)
The amount of heat generated in (8) is also reduced by the parallel connection and the current is dispersed. Depending on the control conditions of the gate control circuits (6) and (9), SCRs (3) and (8) are always used in parallel, or only 5CRs (3) are used at all times to reduce the load by increasing the beam current of the picture tube. S only if becomes heavier
It is also possible to use CR(8) in parallel, and the element capacitance of 5CR(3)(8) can be efficiently selected accordingly.

Figure 2 shows a specific example of the circuit configuration in Figure 1, (10)
connects the commercial AC voltage from the AC plug (11) to the bridge rectifier (12) and the smoothing capacitor (13) (1
4) and the choke coil (15) rectifies and smoothes it as unstable DC voltage (Ein) SCR (3) (8)
The power supply circuit (16) is supplied to the anode side of the SCR (3) (8) through the windings (2) (7) for pulse superimposition.
) is a horizontal output circuit that becomes active when a stabilized DC voltage (Eout) is supplied from the cathode side of the rectifier (17) and the primary winding of a flyback transformer (to be described later); (18) is a horizontal output circuit. A horizontal output transistor is turned on and off by the oscillation output from the oscillation circuit, (19) is a horizontal deflection coil to which a deflection current is supplied by turning on and off the horizontal output transistor (18), (2o) is a damper diode, (21) is a The resonant capacitor (22) is an S-shaped correction capacitor. (23) is its − next winding (
The retrace period pulse from the horizontal output circuit (16) supplied to 23a) is boosted from its secondary winding (23b), rectified by a high-voltage rectifier diode (24), and then supplied to the picture tube as an anode voltage. This is a flyback transformer. Furthermore, (25) (26) is S CR(3) (8
) is a commutation prevention circuit that prevents irregular turn-on that is not caused by gate drive.

Here, the gate control circuit (6) of SCR (3) (8)
) (9) is a diode (28) and a capacitor (
The voltage rectified and smoothed in step 29) is supplied as the power supply voltage for operation. The gate control circuits (6) and (9) are connected to capacitors (3) to which pulses from the tertiary winding (27) are supplied via resistors (30) and (31).
2) The first transistor (34) superimposes the output voltage (Eout) from the cathode side on the charging voltage of (33) (
35), and second transistors (36) (37) whose operation is controlled by supplying the superimposed voltage to the transistor,
The operation is controlled by the second transistors (36) (37) via the differentiating circuits (38) (39), and the SCR(
3) Consists of a third transistor (40) (41,) that outputs a turn-on pulse to the gate of (8), etc. In this case, the control conditions of gate control circuits (6) and (9) are the same. shall be. In addition, the starting circuit (5) of the SCR (3) includes a resistor (42) and a Zener diode (
43) and a backflow prevention diode (44) are connected in series, for example, a resistor (42) and a diode (44) are connected in series.
44) and the voltage drop between the gate and cathode of S
0), and Ein
-When Eout, > ν2, current flows and S
CR(3) is started.

Therefore, when the SCR (3) is started and turned on by the starting circuit (5) when the power supply is started by closing the power switch (45), the capacitor (17) is charged by the output voltage from the cathode side, and the start-up occurs. Circuit (5)
At the same time, the horizontal output circuit (16) is activated to generate a retrace period pulse, and the retrace period pulse is boosted by the flyback transformer (23). At this time, the pulse from the tertiary winding (27) (the third
(see figure (a)) by the gate control circuit (6) (9)
are in operation, and their capacitors (32)
(33) will be charged.

Therefore, the gate control circuit (9) controls the first transistor (
At the voltage at point P (see the solid line in Figure 3(b)), which is the superimposition of the output voltage from the SCR (3) through the SCR (35), the second transistor (37) By being turned on for a period of time, the third transistor (41) is activated by a negative pulse (see Fig. 3(d)) obtained from the differentiating circuit (39).
is turned on instantaneously, and a control pulse as shown in FIG. 3(e) is output. Then, this gate control circuit (9
) will be supplied to the gate of 5CR(8) and S CR(8) will also be turned on.

Then, the turned-on SCR(3) (8) is simultaneously turned off during the retrace period by a negative retrace period pulse supplied to its anode side, and thereafter, the SCR(3)(8) is turned off simultaneously during the retrace period.
3) In (8), the turn-on by the gate control circuit (6) (9) and the simultaneous turn-off by the pulse superimposition windings (2) and (7) are repeated alternately, and the turn-on timing is determined from the cathode side. is controlled based on the value of the output voltage. For example, when the output voltage increases due to a decrease in the beam current of the picture tube, the collector potential of the first transistor (34) (35) decreases by that amount, and the voltage at point P decreases as shown by the dotted line in Figure 3(b). In order to do so, the second. Turning on of the third transistors (36), (37) and (40) (, H) is sequentially delayed as shown in the dotted lines in Figure 3 (c) and (e), and is output from the gate control circuit (6) and (9). Control pulses will also be delayed.

Therefore, the turn-on timing of SCR(3)(8) is delayed, and the voltage output from the cathode side of SCR(3)(8) is reduced. As a result, the output voltage (Eout) from S CR(3) (8)
is always kept constant, and the horizontal output circuit (16
) is always supplied with a stabilized DC voltage for its operation.

In this embodiment, a case has been described in which a combination of a winding for pulse superimposition, an SCR, and a gate control circuit are connected in two stages in parallel, but it is also possible to connect the combination of a winding for pulse superimposition, an SCR, and a gate control circuit in two stages, or use an SCR as a switching element. Although the case is described above, the present invention is not limited to this. Furthermore, instead of the horizontal output circuit, a retrace period pulse of doubtful value υ from a pulse generation circuit having a similar configuration to the horizontal output circuit may be used.

Furthermore, as described above, according to the stabilized power supply circuit of the present invention, by connecting a plurality of SCRs as switching elements in parallel, the amount of heat generated by each SCR can be reduced, and the amount of heat generated by each SCR can be reduced. Since each SCR is individually controlled by a gate control circuit, the element capacitance of the SCR can be efficiently selected.

Furthermore, in the present invention, one of each SCR is activated by a single activation circuit, and the remaining SCRs are activated by a gate control circuit, so there is no need to provide a activation circuit for each SCR. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing a specific circuit configuration example thereof, FIG. 3 is an operation waveform diagram thereof, and FIG. 4 is a block diagram showing a conventional example. be. (2) (7)...-Winding for pulse superimposition. (3) (8) -3CR, (5) -Start circuit (6)
(9) ---Gate control circuit. 11th! I

Claims (3)

[Claims] (1) A stabilized power supply circuit that supplies an unstable DC voltage to a load after stabilizing it through a switching element that repeatedly turns on and off, characterized in that a plurality of the switching elements are connected in parallel. circuit. (2) A first feature characterized in that a control circuit is provided that individually controls each of the switching elements according to load fluctuations.
A stabilized power supply circuit according to the claims. (3) The switching element is a silicon-controlled rectifier element in which an unstable DC voltage is supplied to the anode side via a pulse superimposition winding that superimposes a turn-off pulse, and the control circuit is a silicon-controlled rectifier for each silicon-controlled rectifier. 3. The stabilized power supply circuit according to claim 2, wherein the stabilized power supply circuit is a gate control circuit that supplies a turn-on pulse to a gate of an element at a timing corresponding to a voltage output from the cathode side of the element.