JPS6022695Y2 - television receiver - Google Patents

Description

[Detailed Description of the Invention] Some television receivers have a high voltage generation circuit and a horizontal deflection output circuit made up of a common switching element, and a boost circuit is provided for the horizontal output.

The present invention effectively prevents changes in the image size due to fluctuations in high voltage due to changes in beam current in such television receivers without using a high voltage stabilizing circuit. be.

Hereinafter, a specific example of the television receiver according to the present invention will be explained with reference to the drawings.

Figure 1 shows an example of the present invention, where 1 is a switching transistor that serves both for high voltage generation and horizontal deflection output, its collector is connected to one end of the primary side 2a of the horizontal output transformer 2, and its emitter is grounded. Ru.

A damper diode 3 and a capacitor 4 are connected between the collector of the transistor 1 and the ground, and a horizontal deflection coil 5 and a so-called 5-character correction capacitor 6 are connected.
series circuit is connected.

The power supply terminal 8 is connected to the intermediate tap of the primary side 2a of the transformer 2 via the capacitor 10, the damping resistor 11, and the booster diode 12 in this order.
The other end PA of a is grounded via a capacitor 13 to form a boost circuit 7.

A rectifier circuit 14 is connected to the secondary side 2b of the transformer 2, and a high voltage output is taken out.

In the present invention, the coil 15 is connected in series with the boost diode 12 of the boost circuit 7, that is, in parallel with the series circuit of the capacitor 10 and the damping resistor 11, for example.

In addition, as a specific numerical example, the capacitor 10 is set to 0.
001μF, resistor 11 to 470Ω, coil 15 to 2
Set it to 50μH.

According to the present invention, changes in image size due to fluctuations in high voltage due to changes in beam current are corrected.

That is, when there is no coil 15, the diode 12 has a second
A current flows as shown in Figure A, but in this invention, coil 1
5, a sawtooth wave current flows through the diode 12 as shown in FIG.

When the beam current flows, this diode 7 and 12
The current flowing through the coil 15 increases, the voltage drop across the coil 15 increases, and the boost voltage at the point PA decreases.

For example, in the above numerical example, when the beam current is zero, the boost voltage is 132■, but when the beam current is 1
When mA flows, the boost voltage becomes 129■.

Therefore, when the beam current increases, the high voltage decreases, and the image size is about to increase, the current flowing through the diode 12 increases as shown by the solid line in FIG. 2B, and the boost voltage at point PA increases. As the beam current decreases, the horizontal deflection current flowing through the horizontal deflection coil 5 becomes smaller, and conversely, when the beam current becomes smaller, the high voltage rises and the image size is about to become smaller, the current flowing through the diode 12 decreases as shown in Fig. 2. As shown by the broken line B, the boost voltage at point PA increases, and the horizontal deflection current flowing through the horizontal deflection coil 5 increases.

Therefore, the horizontal deflection current changes to compensate for changes in the image size due to changes in the high voltage, and the image size does not change even if the high voltage changes due to changes in the beam current.

In this case, since the diode 12 is off during the retrace section, the high voltage characteristics are not affected by the connection of the coil 15.

According to this circuit, it is also corrected that the magnitude of the horizontal deflection current changes in the vertical period due to ripples in the power supply voltage having a vertical period, and that the image is curved.

The present invention can be similarly applied to a case where a flyback transformer 16 is provided separately from the horizontal output transformer 2, as in the example shown in FIG.

Note that the coil 15 may be connected between the diode 12 and the intermediate tap of the horizontal output lance 2 on each of the above-mentioned sides.

According to the present invention described above, it is possible to prevent the image size from changing due to fluctuations in high voltage due to changes in beam current without using a high voltage stabilizing circuit.

Furthermore, in the present invention, since the coil 15 is connected in series with the boosting diode 12 of the boost circuit 7, power consumption does not increase unlike when a resistor is connected.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram of one example of the present invention, FIG. 2 is a waveform diagram for explaining the same, and FIG. 3 is a connection diagram of another example of the present invention. 1 is a switching transistor, 2 is a horizontal output transistor,
3 is a damper diode, 5 is a horizontal deflection coil, 7 is a boost circuit, 8 is a power supply terminal, 12 is a boost diode, and 15 is a coil.

Claims (1)

[Scope of utility model registration request] In a device in which a high voltage output and a horizontal deflection output are obtained by a common switching element, and a boost circuit is provided for the horizontal output drance, by connecting a coil in series to the boost diode of the boost circuit,
The television receiver 911& is configured to reduce the horizontal deflection current by lowering the boost voltage by taking into consideration the voltage drop in the coil when the beam current increases, thereby correcting the increase in picture size due to the drop in high voltage.