JPH10233935A - Stabilizing circuit for horizontal pulse output at start of application of power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a stable horizontal deflection circuit operation even for an unstable period from start of application of power till start of the operation of the horizontal deflection circuit and to reduce the power loss. SOLUTION: Only for a period from start of application of power till start of the operation of a horizontal deflection circuit, an input terminal and an output terminal of a voltage regulator connecting to a power supply line through which a voltage is applied to a horizontal pulse output block are connected by a switch element and the operation of the horizontal pulse output block is warranted by compensating the lowered voltage of the voltage on the power supply line than that in the operation of the horizontal deflection circuit through an inactivated voltage drop by the voltage regulator 4. Furthermore, after the horizontal operation, a DC bias is applied to the switch element with a DC voltage obtained by rectifying and smoothing a secondary winding output of a flyback transformer 6 so as to release the connection between the input terminal and the output terminal, thereby operating the voltage regulator 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal pulse at the start of a power supply using a power supply circuit for controlling switching by detecting a voltage change of a power supply line for supplying a voltage to a horizontal deflection circuit in a secondary winding of a switching transformer. It relates to an output stabilization circuit.

[0002]

2. Description of the Related Art Conventionally, a power supply output stabilizing circuit has been disclosed in
Japanese Patent Nos. 41392 and 6-105549 are known.

FIG. 5 shows an example of a conventional circuit, and FIGS.
2 shows the transition of the operating voltage of the conventional circuit. In FIG. 5, reference numeral 1 denotes a switching transformer, 2 denotes a rectifier diode, 3 denotes a smoothing capacitor, 4 denotes a voltage regulator, 5 denotes a horizontal pulse output block, 6 denotes a flyback transformer,
7 is a rectifier diode, 8 is a smoothing capacitor, 9 is a secondary output voltage terminal of 6, 10 is a horizontal output transistor, 11
Represents 10 drive blocks, 12 represents rectifier diodes, 1
3 is a smoothing capacitor, 14 is a resistor, 15 is a photocoupler, and 16 is an error detection amplifier.

In FIGS. 6A and 6B, 1C is at the start of power supply, 2C is at the start of horizontal deflection circuit operation, and 3C is
C is the threshold voltage of the operation guarantee voltage of the horizontal pulse output block 5 of FIG. 5, 4C is the transition of the cathode voltage of the rectifier diode 2 of FIG. 5, and 5C is the horizontal pulse output block 5 of FIG.
, 6C is the potential difference between 4C and 5C before the horizontal deflection circuit operation starts, and 7C is the 4C and 5C potential difference after the horizontal deflection circuit operation starts.

[0005]

In the circuit configuration of FIG. 5, since the horizontal pulse output block 5 is not operated during the period from FIG. 6-1 to FIG. 6-2, the flyback transformer 6 and the horizontal output transistor 10 are also not used. No operation was performed. Therefore, the secondary load is determined to be no load by the error detection amplifier 16, and the on-duty of the switching waveform on the primary side of the switching transformer 1 deviates from the control range in the normal operation and has a narrow waveform. Accordingly, the output impedance of each secondary winding also deviates from the control range during normal operation and increases. On the other hand, the load supplied from the secondary winding of the switching transformer 1 that is not controlled by the error detection amplifier 16 is the same regardless of whether the flyback transformer 6 and the horizontal output transistor 10 are operating or not. In the worst case, the voltage of the smoothing capacitor 3 is lowered by the voltage regulator 4 from the state at the time of normal operation.
As shown in the figure, the horizontal pulse is not output because the voltage 5C applied to the horizontal pulse output block 5 is lower than the operation guarantee voltage threshold value of the horizontal pulse output block 5, and the flyback transformer 6 and the horizontal output transistor 10 do not operate. Would.

In order to avoid the above-mentioned state, a method of reducing the number of windings of the winding of the switching transformer 1 controlled by the error detection amplifier 16 and relatively increasing the winding voltage not controlled by the error detection amplifier 16 is used. However, according to this method, as shown in FIG. 6A, the input / output potential difference of the voltage regulator 4 after the operation of the horizontal deflection circuit is large, which leads to power loss.

[0007]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention relates to a method for controlling a voltage connected to a power supply line for supplying a voltage to a horizontal pulse output block only during a period from a power supply start 1 to a horizontal deflection circuit operation start 2. The input / output terminal of the regulator 4 is short-circuited by a switch element, and the horizontal pulse output block operation is guaranteed by disabling the voltage drop by the voltage regulator 4 to the extent that the voltage of the power supply line becomes lower than that during the horizontal deflection circuit operation. I do.

After the horizontal operation, a DC bias is applied to the switch element by a DC voltage obtained by rectifying and smoothing the output of the secondary winding of the flyback transformer 6 to cancel a short circuit.
In this configuration, the voltage regulator 4 is operated.

Thus, a constant voltage is supplied to the horizontal pulse output block even during an unstable period from the start of the power supply to the start of the operation of the horizontal deflection circuit, thereby ensuring stable operation of the horizontal deflection circuit and reducing power loss. is there.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a power supply circuit for detecting a voltage change of a power supply line for supplying a voltage to a horizontal deflection circuit in a secondary winding of a switching transformer and controlling switching. Wherein the output voltage supplied to the secondary load of the switching transformer is switched using one winding, a transistor, and a resistor in a secondary winding of a flyback transformer. In addition, a constant voltage is supplied to the horizontal pulse output block even during an unstable period from the start of the power supply to the start of the operation of the horizontal deflection circuit, so that stable horizontal deflection circuit operation can be guaranteed and power loss can be reduced.

According to a second aspect of the present invention, there is provided a power supply circuit for detecting switching of a voltage of a power supply line for supplying a voltage to a horizontal deflection circuit in a secondary winding of a switching transformer and controlling switching, and comprising: A horizontal pulse output stabilization circuit at the time of power supply start, wherein an output voltage to be supplied to the secondary load of the switching transformer is switched using one winding in a next winding, a relay, a transistor, and a resistor. 2. A transistor which supplies a constant voltage to the horizontal pulse output block even during an unstable period from the start to the operation of the horizontal deflection circuit to ensure stable horizontal deflection circuit operation and reduce power loss. The switching transformer can be designed to reduce the power loss of VCESAT.

[0012]

【Example】

(Embodiment 1) Hereinafter, a horizontal pulse output stabilization circuit at the time of power supply start according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a circuit diagram of a horizontal pulse output stabilizing circuit at the time of power supply start of the present invention, and FIG. 2 shows a transition of an operating voltage of FIG.

In FIG. 1, reference numeral 1 denotes a switching transformer, 2 denotes a rectifying diode, 3 denotes a smoothing capacitor, 4 denotes a voltage regulator, 5 denotes a horizontal pulse output block, 6 denotes a flyback transformer, 7 denotes a rectifying diode, and 8 denotes a smoothing capacitor. , 9 is a secondary output voltage terminal of 6, 10 is a horizontal output transistor, 11 is a drive block of 10, 1
2 is a rectifier diode, 13 is a smoothing capacitor, 14 is a resistor, 15 is a photocoupler, 16 is an error detection amplifier, 17
Is a transistor, and 18, 19, and 20 are resistors.

In FIG. 2, 1A indicates a power supply start time.
2A indicates the start of the operation of the horizontal deflection circuit, 3A indicates the threshold voltage of the operation assurance voltage of the horizontal pulse output block 5 in FIG. 1, 4A indicates the transition of the cathode voltage of the rectifier diode 2 in FIG. 1, and 5A indicates the horizontal pulse output block 5 in FIG. The applied voltage transition, 6A is 4A before starting the horizontal deflection circuit operation.
The potential difference between A and 5A, 7A is the potential difference between 4A and 5A after the start of the horizontal deflection circuit operation.

The operation of the above-configured horizontal pulse output stabilizing circuit at power supply start will be described below.

When the power supply is started, the voltage of 4A in FIG. 2 is output from the switching transformer 1 and the smoothing capacitor 3 is charged. At this time, the transistor 17 is turned on by the resistors 18 and 19, the voltage drop by the voltage regulator 4 is invalidated, and the horizontal pulse output block 5 receives 5A in FIG.
As shown in FIG. 2, a voltage lower than the voltage of 4A in FIG. 2 by VCESAT of the transistor 17 is applied.
It exceeds the operation guarantee voltage threshold value 3 of the horizontal pulse output block 5.

Next, when the flyback transformer 6 and the horizontal output transistor 10 start operating, the rectifier diode 7
, The voltage is charged in the smoothing capacitor 8. Then, the transistor 17 is cut off via the resistor 20, and 4A in FIG.
A voltage value.

(Embodiment 2) Next, a horizontal pulse output stabilizing circuit at power supply start according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 3 is a circuit diagram of the horizontal pulse output stabilizing circuit at the time of power supply start of the present invention, and FIG. 4 shows the transition of the operating voltage of FIG.

In FIG. 3, 1 is a switching transformer,
2 is a rectifier diode, 3 is a smoothing capacitor, 4 is a voltage regulator, 5 is a horizontal pulse output block, 6 is a flyback transformer, 7 is a rectifier diode, 8 is a smoothing capacitor, 9 is a secondary output voltage terminal of 6, 10 Is a horizontal output transistor, 11 is a drive block of 10, 12 is a rectifier diode, 13 is a smoothing capacitor, 14 is a resistor,
5 is a photocoupler, 16 is an error detection amplifier, 17 is a relay, 18 is a transistor, and 19, 20, and 21 are resistors.

Further, in FIG.
2B is a horizontal operation start time, 3B is an operation guarantee voltage threshold value of the horizontal pulse output block 5 in FIG. 3, 4B is a transition of the cathode voltage of the rectifier diode 2 in FIG. 3, and 5B is applied to the horizontal pulse output block 5 in FIG. Voltage transition,
6B is the potential difference between 4B and 5B before the start of the horizontal operation (there is no theoretical potential difference because the relay 17 is used as a switch element), and 7B is the 4th potential after the start of the horizontal operation.
B, 5B.

The operation of the above-configured horizontal pulse output stabilizing circuit at the start of power supply will be described below.

When the power supply is started, the voltage of 4B in FIG. 4 is output from the switching transformer 1 and the smoothing capacitor 3 is charged. At this time, the transistor 18 is turned on by the resistors 19 and 20, the relay 17 is also turned on, the voltage drop by the voltage regulator 4 is invalidated, and as shown in FIG. 4B is directly applied to the horizontal pulse output block 5 and exceeds the operation guarantee voltage threshold value 3 of the horizontal pulse output block 5.

Next, when the flyback transformer 6 and the horizontal output transistor 10 start operating, the rectifier diode 7
, The voltage is charged in the smoothing capacitor 8. Then, the transistor 17 is cut off via the resistor 20, and 4B in FIG.
B voltage value.

[0026]

As described above, according to the horizontal pulse output stabilizing circuit at the time of power supply start of the present invention, the voltage regulator operation is switched by using the secondary output voltage of the flyback transformer as a trigger. In this case, a stable voltage can be supplied even during unstable operation of the power supply circuit, the horizontal pulse output becomes stable, and a stabilization circuit including a switching transformer that minimizes power loss is realized.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a horizontal pulse output stabilization circuit at power supply start according to an embodiment of the present invention.

FIG. 2 is an operation diagram of a secondary output voltage in FIG. 1;

FIG. 3 is a circuit diagram of a horizontal pulse output stabilization circuit at power supply start according to an embodiment of the present invention.

FIG. 4 is an operation diagram of a secondary side output voltage in FIG. 3;

FIG. 5 is a circuit diagram of a conventional horizontal pulse output circuit at power supply start.

FIG. 6 is a diagram showing the operation of the secondary output voltage in FIG. 5;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 switching transformer 2 rectifier diode 3 smoothing capacitor 4 voltage regulator 5 horizontal pulse output block 6 flyback transformer 7 rectifier diode 8 smoothing capacitor 9 6 secondary output voltage terminal 10 horizontal output transistor 11 10 drive block 12 rectifier diode 13 smoother Capacitor 14 Resistance 15 Photocoupler 16 Error detection amplifier 17 Transistor 18 Resistance 19 Resistance 20 Resistance

Claims (2)

[Claims] 1. A secondary winding of a switching transformer,
In a power supply circuit that detects a voltage change of a power supply line that supplies a voltage to a horizontal deflection circuit and controls switching, one winding in a secondary winding of a flyback transformer, a transistor,
A horizontal pulse output stabilizing circuit at power supply start, wherein an output voltage supplied to a secondary load of the switching transformer is switched using a resistor. 2. The secondary winding of a switching transformer,
In a power supply circuit for controlling switching by detecting a voltage change of a power supply line for supplying a voltage to a horizontal deflection circuit, a secondary winding of a flyback transformer, a relay, a transistor, and a resistor are used. A horizontal pulse output stabilizing circuit at the time of power supply start, wherein an output voltage supplied to a side load is switched.