JP2643372B2 - Flyback transformer device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flyback transformer device used for a television receiver or the like.

2. Description of the Related Art The high-voltage output voltage regulation characteristics of a flyback transformer affect the screen of a television receiver,
If the regulation characteristics are poor, the width of the screen of the television receiver changes with the output voltage of the flyback transformer. For this reason, there has conventionally been a device in which the horizontal deflection pulse is changed according to the output voltage of the flyback transformer as shown in FIG. In FIG. 3, reference numeral 20 denotes a flyback transformer.
And a secondary winding 22 of a saturable reactor transformer 21 is connected in parallel. A horizontal output transistor 19 supplies a horizontal deflection pulse to the primary winding 1 of the flyback transformer 20. Numeral 2 denotes a secondary winding of the flyback transformer 20. The output voltage of the secondary winding 2 is divided to provide a differential amplifier.
Has been added to 10. The output of the differential amplifier 10 is applied to the primary winding of the correction transformer 21. The television receiver using the conventional flyback transformer as described above is
If the high-voltage output voltage of the flyback transformer 20 changes due to the increase or decrease of the beam current and deviates from the reference voltage, the differential amplifier
The output voltage appears at the 10 output terminals. As a result, the current flowing in the primary winding of the correction transformer 21 changes and the inductance of the secondary winding 22 changes, so that the horizontal deflection pulse voltage generated in the primary winding 1 of the flyback transformer also changes,
The output voltage regulation characteristics of the flyback transformer 20 are improved.

There is also a conventional flyback transformer device as shown in FIG. That is, 1 is 1 of the main flyback transformer.
A secondary coil 2 is a secondary coil, and a switching pulse coil 3 is wound around a common core 11. Reference numeral 4 denotes a primary coil of an auxiliary transformer, and reference numeral 5 denotes a secondary coil, each of which is wound on a core 12. 6 is a rectifier diode for the auxiliary transformer, 7 is a smoothing capacitor,
9 is a high-voltage detection resistor, 10 is a differential amplifier, and 13 is a switching element. In the case of this example, when the high-voltage output voltage changes, the voltage divided by the high-voltage detection resistors 8 and 9 also changes, and a signal indicating the change is applied to the differential amplifier 10 and the output amplified and compared with the reference voltage. Are output from the differential amplifier 10. Therefore, the switching pulse of the coil 3 connected to the output terminal of the differential amplifier 10 changes. As a result, the ON time of the switching element 13 changes, the output voltage of the auxiliary transformer changes, and the high output voltage of the flyback transformer 23 can be kept constant.

However, when the conventional flyback transformer as described above is used, in order to control the output voltage of the flyback transformer, the input voltage to the flyback transformer, that is, the horizontal pulse, is controlled by an automatic frequency control circuit or the like. When used as a reference pulse, the voltage and waveform of this reference pulse change,
The automatic control circuit becomes unstable. Further, when the input voltage changes, there is a problem that the width of the screen changes. In addition, the control of a large current portion on the primary side requires a control element having a large loss and a coil having a thick winding, which has a disadvantage of increasing the cost of the product.

Further, in the case of a device using a conventional flyback transformer as shown in FIG. 4, since the secondary side is controlled, there is no such a drawback as described above. Since the ON time is controlled and the reaction speed when keeping the high voltage output voltage constant is not sufficient, the dynamic regulation of the high voltage output voltage may not be sufficiently improved.

Means for Solving the Problems In order to solve the above problems, the flyback transformer device of the present invention connects a capacitor in parallel to the secondary coil of the flyback transformer and magnetically couples the flyback transformer in series with the secondary coil of the flyback transformer. The decoupling connects the secondary coil of the auxiliary transformer, connects the switching element to one end of the primary coil of the auxiliary transformer and connects the power supply to the other end, and turns the switching element on and off in synchronization with the flyback pulse. The on-time is longer when the output voltage of the sum of the output voltage of the secondary coil of the flyback transformer and the output voltage of the secondary coil of the auxiliary transformer drops than when it rises. .

According to the above configuration, the DC bias voltage of the switching flyback pulse is changed according to the change of the output voltage of the sum of the output voltage of the secondary coil of the flyback transformer and the output voltage of the secondary coil of the auxiliary transformer. The pulse width of the correction current flowing through the correction transformer is controlled, the output voltage of the correction transformer changes, the voltage on the secondary side of the flyback transformer is kept constant, and the secondary side of the flyback transformer is connected in parallel. The impedance on the secondary side of the flyback transformer is reduced by the capacitor connected to
The output voltage of the auxiliary transformer appears immediately on the secondary side of the flyback transformer.

Embodiment Hereinafter, an embodiment of the flyback transformer device of the present invention will be described in detail.

FIG. 1 is a wiring diagram of one embodiment of the present flyback transformer device. 1 is a primary coil of a main flyback transformer, 2 is a secondary coil, and 3 is a switching pulse coil, each of which is wound on a common core 11. 4
Is a primary coil of the auxiliary transformer, and 5 is a secondary coil, which is wound on the core 12. The core 11 and the core 12 are not magnetically coupled to each other. Reference numeral 6 denotes a rectifying diode of the auxiliary transformer, and 7 denotes a smoothing capacitor which is connected to the secondary coil 5 to form a rectifying circuit. Reference numerals 8 and 9 denote high voltage detecting resistors which divide the output voltage of the secondary coil 2. Reference numeral 10 denotes a differential amplifier. One input terminal is connected to a connection terminal of the resistors 8 and 9, and the other input terminal is connected to a reference power supply. Reference numeral 13 denotes a switching element, which uses a metal oxide film field effect transistor (MOSFET).
Reference numeral 14 denotes a capacitor which is connected to the positive terminal of the secondary coil 2 via a rectifier diode, and is directly connected to the negative terminal.

The flyback transformer of the present invention has the above configuration and is used for a horizontal deflection circuit and a high voltage generation circuit as shown in FIG. Reference numeral 19 denotes a horizontal output transistor, 15 denotes a deflection yoke, 16 denotes an S-shaped correction capacitor, 17 denotes a resonance capacitor, and 18 denotes a damper diode, forming a horizontal deflection circuit.

The operation when used in the above-described horizontal deflection circuit will be described. A horizontal drive pulse is applied to the transistor 19, and a horizontal deflection flyback pulse is generated in the primary coil 1 of the flyback transformer. A similar flyback pulse voltage is induced in the secondary coil 2, and a high DC voltage is generated. Similarly, a flyback pulse is also generated in the switching coil 3. The terminal on the positive pulse side of the switching coil 3 is connected to the gate of the switching element 13, and the terminal on the negative pulse side is connected to the output of the differential amplifier 10. The differential amplifier 10 is biased to operate with a negative output. A switching element 13 for performing a switching operation by a pulse from the switching coil 3 and a DC power supply are connected in series to the primary coil 4 of the auxiliary transformer. Secondary coil 5 of auxiliary transformer
A rectifier circuit including a rectifier diode 6 and a capacitor 7 is formed at the output end of the main flyback transformer. The rectifier circuit is connected to the winding start end of the secondary coil 2 of the main flyback transformer. The sum of the output voltages is obtained at the final output terminal, and further connected to the secondary coil 2 of the main flyback transformer via a rectifier diode. When the high voltage output voltage decreases due to an increase in the load current, the voltage divided by the high voltage detection resistors 8 and 9 also decreases. This signal is applied to the differential amplifier 10, and an output that is compared and amplified with the reference voltage is obtained. The output of the differential amplifier 10 approaches 0 V from minus. The switching coil 3 and the output side of the differential amplifier 10 are connected in series, and when the output voltage of the differential amplifier 10 increases, the switching element 13
The voltage applied to the gate of the gate also increases. That is, it is applied to the gate of the switching element 13. The flyback pulse has a form in which the positive half wave of the sine wave is biased by the negative DC voltage as shown in FIG. Therefore, when the bias voltage approaches 0 V, the ON time of the switching element 13 increases. This is because the switching element 13 has a characteristic that it turns on when the voltage between the gate and the source reaches a certain threshold voltage, and when the negative bias voltage approaches 0V,
This is because the width of a portion above a certain threshold level of the flyback pulse increases. As a result, the output voltage of the auxiliary transformer increases. On the other hand, the output terminal of the secondary coil 5 of the auxiliary transformer is connected to the winding start end of the secondary coil 2 of the main transformer via a rectifier circuit, and the positive terminal of the secondary coil 2 of the main transformer via a capacitor 14. Is connected via a rectifier diode, so that a so-called change in the output voltage of the auxiliary transformer appears at the output end of the secondary coil 2 of the main transformer through the capacitor 14, and as a result, the high-voltage output voltage increases. Then, control for stabilizing the high-voltage output voltage is performed.

When the high-voltage output voltage becomes high, the operation opposite to the above is performed, and similarly, the control for stabilizing the high-voltage output voltage is performed.

In this embodiment, the auxiliary transformer is connected to the low voltage side of the secondary side of the main transformer. However, the connection position may be connected to the secondary coil of the main transformer in series. Even at the high voltage output end, the effect remains unchanged.

According to the present invention, as described above, the auxiliary transformer that is magnetically uncoupled from the flyback transformer is connected in series to the secondary coil of the flyback transformer, and the width is varied according to the output voltage of the secondary coil. The high-voltage output voltage is stabilized without changing the horizontal deflection pulse voltage because the capacitor is connected in parallel with the secondary coil of the flyback transformer by correcting the changing pulse by applying it to the auxiliary transformer. In addition, it is possible to cope with a sudden change in the high-voltage output voltage. Therefore, even if the horizontal deflection pulse is used in an automatic frequency control circuit, a blanking circuit, or the like, there is no particular problem.In addition, there is no need to change the width of the horizontal deflection pulse in order to stabilize a high output voltage. There is no need to change the input voltage to the primary coil. For this reason, it is possible to realize a screen with little amplitude fluctuation.

Further, in the flyback transformer device of the present invention, control is performed only on the secondary side, so that the primary side and the secondary side can be insulated from each other, so that safety is enhanced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of one embodiment of a flyback transformer device of the present invention, FIG. 2 is a circuit diagram of a horizontal deflection circuit using the flyback transformer device, and FIGS. 3 and 4 are conventional flyback transformer devices. FIG. 5 is a circuit diagram of a horizontal deflection circuit having a high-voltage stabilizing function using a transformer device, and FIG. 5 is a flyback pulse waveform diagram. DESCRIPTION OF SYMBOLS 1 ... Primary coil (main flyback transformer) 2 ... Secondary coil (main flyback transformer) 3 ... Switching coil 4 ... Primary coil (auxiliary transformer) 5 ... Secondary coil (auxiliary transformer) 6 ... Diode, 7 ... Capacitor 8, 9 ... High voltage detection resistor 10 ... Differential amplifier, 11, 12 ... Core 13 ... Switching element 14 ... Capacitor 15 ... Deflection yoke 16 ... S-shaped capacitor 17 …… Resonant capacitor 18 …… Damper diode 19 …… Transistor 20 …… Flyback transformer 21 …… Compensation transformer 22 …… Transistor

Claims (1)

(57) [Claims] 1. A secondary coil of an auxiliary transformer which is magnetically non-coupled with the flyback transformer is connected in series with a secondary coil of the secondary transformer of the flyback transformer. A switching element is connected to one end of the coil and a power supply is connected to the other end. The switching element is turned on and off in synchronization with a flyback pulse, and the output voltage of the secondary coil of the flyback transformer and the secondary voltage of the auxiliary transformer are connected. A flyback transformer device wherein the on-time is longer when the output voltage of the sum of the output voltage of the coil and the output voltage drops than when the output voltage rises.