JPS6244460B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power supply circuit for starting horizontal oscillation.

A television receiver equipped with a conventional power supply circuit for starting horizontal oscillation is shown in FIGS. 1 and 2.

The television receiver shown in FIG. 1 is semi-cold, with the power supply rectification/stabilization circuit 1 and the horizontal output circuit 2 serving as live parts, and the other parts being non-live parts. The live parts and non-live parts are separated by transformers T ₁ , T ₂ and flyback transformer T ₃ . Power for each circuit, except for the horizontal output circuit 2, is supplied by rectifying and smoothing horizontal pulses obtained from a flyback transformer _T3 .
For this purpose, it is necessary to operate the horizontal deflection circuit, but since the horizontal oscillation/drive circuit 3 is a non-charging section, power must be supplied separately from the charging section. For this reason, a transformer T ₁ is provided,
A non-charged DC voltage is obtained by rectifying and smoothing the secondary output of the transformer _T1 using a diode _D1 and a capacitor _C1 . This uncharged DC voltage is supplied as a starting power source for the horizontal oscillation/drive circuit 3, and then the horizontal pulse obtained from the flyback transformer _T3 is rectified and smoothed by a diode _D2 and a capacitor _C1 to convert it into a DC voltage. A voltage is obtained, and this DC voltage is supplied to the horizontal oscillation/drive circuit 3 to sustain the operation of the horizontal deflection circuit. Note that the transformer _T2 performs impedance conversion as a drive transformer as well as separating a charging part and a non-charging part. In addition, the power supply for the signal system circuit 4, etc. other than the horizontal deflection circuit uses a non-charged DC voltage obtained by rectifying and smoothing the horizontal pulse obtained from the flyback transformer T ₃ with a diode D ₃ and a capacitor C ₂ . There is.

Horizontal oscillation start power supply circuits T ₁ , D ₁ , C ₁ used in the television receiver shown in FIG.
In this case, the primary winding of the transformer _T1 is located on the AC power supply side, and due to the impedance seen from the AC power supply side, it was not possible to use a transformer with a very small capacity, resulting in high costs.

The television receiver shown in Fig. ₂ is also semi-cold, and _the circuit division of live and non-charged parts is the same as in Fig. ₁ . and non-current parts are separated. The difference from FIG. 1 lies in the method of supplying power for starting the horizontal oscillation/drive circuit 3, and the other configurations are the same.
When the power switch S ₁ is turned on, the AC voltage is rectified by the diodes D ₄ , D ₅ , D ₆ , and D ₇ and charged to the smoothing capacitor C ₃ via the choke transformer T ₄ . At this time, charging current flows through this smoothing capacitor _C3 , which causes the chiyoke transformer to
The pulse induced on the secondary side of T ₄ passes through diode D ₁
The voltage is then rectified and smoothed by a capacitor _C1 , and this voltage is supplied to the horizontal oscillation/drive circuit 3 for starting. Note that 1a is a stabilizing circuit, and the other configurations are the same as those in FIG. 1, so explanations will be omitted.

The horizontal oscillation start power supply circuits T ₄ , C ₃ , D ₁ , used in the television receiver shown in FIG.
C ₁ is also a chiyoke transformer T ₄ similar to the one in Figure 1.
Since the primary winding of the is the path for power supply,
This Chiyoke transformer _T4 could not be used with a small capacity, resulting in high costs. Furthermore, the horizontal oscillation start power supply circuits T ₄ , C ₃ , D ₁ , and C ₁ cannot operate the horizontal oscillation/drive circuit 3 under the condition that the AC power supply voltage gradually increases from zero. .

Therefore, an object of the present invention is to provide an inexpensive power supply circuit for starting horizontal oscillation, which can start horizontal oscillation even when the AC voltage gradually increases.

FIG. 3 shows a television receiver equipped with a horizontal oscillation start power supply circuit according to an embodiment of the present invention. The television receiver shown in Fig. 3 is also semi-cold, and the circuit division of live parts and non-live parts is the same as the television receiver shown in Figs. ₁ and 2. A live part and a non-live part are separated by transformer _T3 and transformer _T5 . The difference from the conventional example lies in the method of supplying the starting power to the horizontal oscillation/drive circuit 3, and the other configurations are the same. When the television receiver operates, a rectified and stabilized DC voltage is obtained from point A. A blocking oscillation circuit is constructed which operates when this DC voltage is supplied, and its output is supplied as a starting power source for the horizontal oscillation/drive circuit 3. Point B is set to a DC voltage by resistor R ₁ and capacitor C ₄ , and a constant voltage divided by resistors R ₂ and R ₃ is applied to the base of transistor Q ₁ . The emitter potential of transistor _Q1 is initially equal to the potential at point B when DC voltage is supplied from point B through capacitor _C5 , but capacitor _C5 is charged with a time constant of capacitor _C5 x resistor _R4 . As a result, the voltage gradually decreases by the charging voltage of capacitor _C5 . When the emitter potential of transistor Q ₁ falls below its base potential, transistor Q ₁ is turned on and collector current flows in the primary winding of transformer T ₅ . Furthermore, the capacitor
Since positive feedback is applied by _C6 , the transistor _Q1 becomes saturated in an instant, and the charging voltage of the capacitor _C5 is also discharged by the transistor _Q1 . When the charging voltage of capacitor C ₅ is discharged, the transistor
The emitter potential of Q ₁ rises to the potential at point B, and transistor Q ₁ is turned off. The above operation is repeated, and during this operation, transistor Q ₁
When turned on, collector current flows through the primary winding of transformer _T5 , so the induced voltage in the secondary winding of transformer _T5 is rectified and smoothed by diode _D1 and capacitor _C1 , and the horizontal oscillation/drive circuit Supplied as starting power for step 3. The other operations are the same as those of the conventional example, so the explanation will be omitted.

In this way, the horizontal oscillation start power supply circuit of this embodiment extracts the DC voltage from the power rectification/stabilization circuit 1, causes blocking oscillation using this DC voltage, and uses the oscillation output to transform the transformer _T5.
In order to rectify and smooth the induced voltage of the secondary winding of transformer T5 and apply it to the horizontal oscillation/drive circuit 3, which is a non-charged part, as a non-charged starting power supply voltage, the horizontal oscillation/drive circuit ₃ It is possible to design a device with a small capacity by passing enough current to start the device. Also, in terms of cost, transistor Q ₁ , resistors R ₁ to R ₄ , and capacitors C ₅ and C ₆ are added, but since transformer T ₅ can be designed with a small capacity, the total cost is lower than that of the conventional example. Become. Furthermore, since blocking oscillation is used, horizontal oscillation can be started even when the AC voltage gradually increases.

As described above, the power supply circuit for horizontal oscillation start of the present invention includes a power supply rectification/stabilization circuit that rectifies and stabilizes the AC power supply voltage, and a blocking circuit that starts oscillation operation by being supplied with power from the power supply rectification/stabilization circuit. The induced voltage in the oscillation circuit and the secondary winding of the isolated transformer of this blocking oscillation circuit is rectified and smoothed and applied as a non-charging starting power supply voltage to the horizontal oscillation/drive circuit, which is a non-charging part. Since it is equipped with a rectifying and smoothing circuit, horizontal oscillation can be started even when the AC voltage gradually increases, and the transformer that constitutes the blocking oscillation circuit has a small capacity and is therefore inexpensive.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams of a television receiver equipped with a conventional horizontal oscillation start power supply circuit, respectively, and FIG. 3 is a circuit diagram of a television receiver equipped with a horizontal oscillation start power supply circuit according to an embodiment of the present invention. FIG. 2 is a circuit diagram of a receiver. 1...Power rectification/stabilization circuit, 3...Horizontal oscillation/drive circuit, _Q1 ...Transistor, R1 _~
R ₄ ... Resistor, C ₁ , C ₄ , C ₅ ... Capacitor, T ₅ ...
…transformer, D ₁ …diode.

Claims (1)

[Claims] 1. Power supply rectifier that rectifies and stabilizes AC power supply voltage.
A stabilizing circuit, a blocking oscillator circuit that starts oscillation when powered by the power supply rectifier/stabilizer circuit, and a blocking oscillator circuit that rectifies and smoothes the induced voltage in the secondary winding of the isolated transformer of the blocking oscillator circuit. A horizontal oscillation start power supply circuit that includes a rectifier and smoothing circuit that applies a non-charged start power supply voltage to the horizontal oscillation/drive circuit that is a charging section.