JPS5836544B2 - Vertical deflection power circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vertical deflection power supply circuit that can be used in a television receiver, and which reduces ripples in the voltage for the vertical deflection circuit taken out from a flyback transformer and does not cause raster vertical line distortion. Yo (purpose of rubbing.

Conventionally, this type of vertical deflection circuit has been constructed, for example, as shown in FIG.

In Figure 1, 1 is a flyback transformer,
A secondary winding 2 for extracting voltage is provided on the secondary side of the flyback transformer 1.

The middle point of this secondary winding 2 is grounded, one end is connected to the anode of a diode 3, and the other end is connected to the cathode of a rectifying diode 4.

The cathode of the diode 3 is led to the output terminal 5 and grounded via a smoothing capacitor T, and the anode of the diode 4 is led to the output terminal 6 and grounded via the smoothing capacitor 8. Combimentary connected vertical output transistor 11
．． 12, the collector of the vertical output transistor 11 is connected to the cathode of the diode 3 and the emitter of the vertical drive transistor 10 via the resistor 9, and the collector of the vertical output transistor 12 is connected to the anode of the diode 4. It is connected.

Between the bases of both vertical output transistors 11.12, a series connection circuit of diodes 13 and 14 is inserted to compensate for the VBE of these vertical output transistors 11.12, and between the base and collector of the vertical output transistors 12, A load resistor 15 is inserted.

Reference numeral 16 denotes a vertical deflection coil connected between the connection point of the vertical output transistors 11 and 12 and ground.

A vertical drive signal is applied to a terminal 17 connected to the base of the vertical drive transistor 10.

In this circuit, a positive DC voltage is obtained from the output terminal 5 and a negative DC voltage is obtained from the output terminal 6.

The voltage appearing at the output terminals 5 and 6 can also be used as a power source for a vertical oscillation circuit or the like.

That is, the voltage obtained from the secondary winding 2 is rectified by the diodes 3 and 4, and smoothed by the capacitors 7 and 8 to become a DC voltage.

The vertical drive signal applied from the terminal 17 is amplified by the drive transistor 10, drives a pair of complementary-connected output transistors 11, 12, and causes a vertical deflection current to flow through the vertical deflection coil 16.

During the first half of deflection, the positive DC current obtained from the diode 3 and capacitor 7 flows through the output transistor 11 to the vertical deflection coil 16, and during the second half, the current flows through the output transistor to the capacitor 8 and diode 4.

If you want to change the raster position in order to correctly adjust the center of the picture tube raster, you can change the base bias voltage of the drive transistor 10 and change the DC level of the vertical drive signal in the positive or negative direction. good.

In this way, the emitter potentials of the output transistors 11 and 12 are displaced in the positive or negative direction, and either positive or negative direct current flows through the vertical deflection coil 16 superimposed on the vertical deflection current, and the centering of the raster is adjusted. It is something that can be done.

Since this superimposed direct current is small, good raster centering adjustment is possible without adversely affecting vertical deflection scanning.

However, as mentioned above, if the positive DC current in the first half of vertical scanning and the negative DC current in the latter half differ slightly from each other due to centering adjustment, the amplitudes of their respective AC components, that is, ripple components, will naturally also differ from each other. .

In other words, even if it is assumed that the power supply output impedance of the positive and negative DC power supplies is the same, if the extraction current (power) used by the load circuit connected to the output terminals 5 and 6 is different, the positive and negative DC currents will be different. This is because the ripple voltages are different and the effects on the primary side of the flyback transformer 1 are different.

This has a negative effect on the primary side, especially when the horizontal deflection circuit connected to the primary side of the flyback transformer 1 uses a thyristor element and is a high impedance circuit.

In this way, the ripple on the secondary side of the flyback transformer 1 affects the primary side through inductance coupling, and as a result, the horizontal deflection output circuit on the primary side is modulated in the vertical direction, resulting in raster vertical line distortion.

These are the ripple voltages of the positive and negative power supplies, an alternating current that is superimposed on the direct current appearing at the output terminal 5, and an alternating current that is superimposed on the direct current that appears at the output terminal 6.

By reducing the alternating current of the positive and negative direct currents, that is, the ripple voltage, there will be no influence on the primary side of the flyback transformer, and a beautiful image without vertical line distortion can be obtained.

The present invention is designed to reduce ripples on the secondary side of a flyback transformer to obtain a beautiful image.One embodiment of the present invention will be described below with reference to FIG. 2 of the drawings.

In FIG. 2, the same parts as in FIG. 1 are given the same numbers and will be explained.

A feature of this circuit is that a capacitor 18 is inserted between the output terminal 5 and the output terminal 6.

This capacitor 18 cancels out the alternating current that is superimposed on the positive DC voltage and the alternating current that is superimposed on the negative DC voltage, and as a result both the positive and negative ripples are reduced and the flyback This eliminates any adverse effects on the primary side of the transformer 1.

Therefore, a beautiful television image can be obtained without causing vertical line distortion in the raster due to modulation of the horizontal deflection circuit.

As described above, according to the present invention, when windings are provided to supply positive and negative voltages from the secondary side of a flyback transformer to a vertical deflection circuit, etc., the ripple difference between the positive and negative voltages causes the horizontal A beautiful television image can be provided without adversely affecting the deflection circuit.

[Brief explanation of drawings]

FIG. 1 is a conventional vertical deflection power supply circuit diagram, and FIG. 2 is a circuit diagram of a vertical deflection power supply circuit according to an embodiment of the present invention. 1...Flyback transformer, 2...
Secondary winding, 3, 4... Diode, 5, 6...
...Output terminal, 7,8,18...Capacitor, 10...Drive diode, 11,12
...Output transistor, 16...Vertical deflection coil, 17...Terminal.

Claims (1)

[Claims] 1 A winding is provided on the secondary side of the flyback transformer, the middle point of this winding is grounded, and the positive and negative pulses obtained from both ends are rectified and smoothed respectively, and the positive and negative DC voltages are taken out and guided to the output terminals respectively. The above-mentioned direct current voltage and the above-mentioned negative current voltage are applied to the respective collectors of a pair of mentally connected vertical output transistors, a vertical deflection coil is connected to the interconnection point of both the above-mentioned vertical output transistors, and a voltage is applied between the above-mentioned pair of output terminals. A vertical deflection power supply circuit characterized in that a capacitor is connected to the vertical deflection power supply circuit.