JP2000316101A - Deflection circuit and television receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a television receiver in which compression can not be generated in the image on a tube screen. SOLUTION: This television receiver in a bi-directional deflection system is provided with a horizontal deflection circuit 1 and a vertical deflection circuit 2 which respectively control a horizontal direction coil 3 and a vertical deflection coil 4, and symmetrical output currents approximating to a sign waveform are generated by the horizontal deflection circuit 1 so that reciprocating horizontal scanning periods can be obtained, and picture display can be executed in both reciprocating horizontal scanning periods. This television receiver is provided with a correcting circuit which cancels the reciprocating components of the cross talk components by using correcting currents extracted from the output currents of the horizontal deflection circuit 1, and a deflection circuit which removes any scanning deviation generated due to the cross talk between the horizontal deflection coil 3 and the vertical deflection coil 4. Thus, the compression of scanning lines on the tube screen can be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection circuit of a television receiver, and more particularly to a bidirectional deflection type deflection circuit using a sine waveform approximation as a horizontal deflection current.

[0002]

2. Description of the Related Art In recent years, there has been proposed a television receiver using a bidirectional deflection system as a horizontal deflection circuit for the purpose of reducing the power of the deflection circuit.

FIG. 6 shows a vertical deflection current waveform in an ideal bidirectional deflection system and how it is viewed on a tube surface. FIG. 6 (a)
FIG. 6B shows an ideal vertical deflection current waveform. By forming a vertical sawtooth current waveform in a stepwise manner, the difference between the forward and backward current values becomes uniform. As shown in (1), the forward and backward scanning lines appear parallel on the tube surface.

[0004]

However, in an actual deflection circuit, a leak component of a horizontal deflection current is superimposed on a vertical deflection current component due to unavoidable crosstalk between the horizontal deflection coil and the vertical deflection coil. Scan lines will be dense and dense on the tube surface. This will be described with reference to FIG.

FIG. 7A is a schematic diagram of a horizontal deflection current waveform component leaking into a vertical deflection current waveform. Due to the mechanical positional relationship between the horizontal coil and the vertical coil, the leakage waveform is superimposed with a phase shift. The vertical deflection current waveform at this time is shown in FIG. FIG. 7C shows the appearance on the tube surface.

Although it is possible to obtain the ideal waveform shown in FIG. 6A by removing the leak component shown in FIG. 7A, it is necessary to adjust the phase and amplitude, and all the leaks are required. The removal of components requires a corresponding amount of power, which is contrary to the idea of a bidirectional deflection circuit for reducing power.

An object of the present invention is to provide a television receiver which solves such a conventional problem and does not cause unevenness in the appearance on the tube surface.

[0008]

In order to achieve this object, a deflection circuit according to the present invention is provided with a correction circuit which acts in a direction to cancel a reciprocal difference of a leakage component (crosstalk component) of a horizontal deflection current to a vertical deflection current. It has a circuit.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A deflection circuit according to the present invention includes a correction circuit which acts in a direction for canceling a reciprocal difference of a leakage component (crosstalk component) of a horizontal deflection current to a vertical deflection current, and has an amplitude. Adjustment only, no phase adjustment required
Further, since not all the leak components are canceled, power consumption can be reduced as compared with the case where all the leak components are removed, and the density of the scanning lines can be reduced.

An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, deflection currents generated from a horizontal deflection circuit 1 and a vertical deflection circuit 2 are applied to a horizontal deflection coil 3 and a vertical deflection coil 4, respectively. At this time, the current / voltage conversion circuit 5 for converting the horizontal deflection current waveform into a voltage passes through the normal rotation circuit 6 or the inversion circuit 7 in order to convert the voltage of the horizontal deflection current waveform and select the polarity of the leakage component due to the mechanical configuration of the deflection coil. The polarity is switched by the switching circuit 8 for selecting one of the waveforms, the amplitude is adjusted by the amplitude adjusting circuit 9, and the correction waveform is superimposed on the vertical deflection current through the transformer 10.

Hereinafter, the waveforms of the respective parts will be described. FIG. 2 shows a crosstalk component and a waveform of a round-trip difference which causes the density of the scanning line to be low. The crosstalk component 11 to the vertical deflection current waveform is out of phase with respect to the basic waveform 12. The reciprocal difference 13 of the crosstalk component appears as the density of scanning lines on the tube surface.

FIG. 3 shows the corrected waveform. Round trip difference 13
To the corrected waveform 1 by superimposing the corrected waveform 14 on
5 is symmetrical in reciprocation. As a result, as shown in FIG. 4, the density of the scanning lines reciprocating visually on the tube surface disappears. Also, at this time, the amplitude of the correction waveform is necessarily smaller than the crosstalk component, so that the power can be reduced compared to canceling all the crosstalk components. The phase of the corrected waveform is not symmetric with respect to the difference waveform due to the delay of the circuit or the like, but as shown in FIG.
By adjusting only the amplitude at the midpoint 17, the corrected differential waveform 17 becomes symmetrical in a reciprocating manner, so that the density of the scanning lines can be eliminated and the necessity of phase adjustment can be eliminated.

[0014]

As described above, the deflection circuit of the present invention is provided with a correction circuit which acts in the direction of canceling the round trip difference of the leakage component (crosstalk component) of the horizontal deflection current to the vertical deflection current. Because only amplitude adjustment does not require phase adjustment and does not cancel all leakage components, power consumption can be reduced as compared to removing all leakage components, and the density of scanning lines can be reduced. This is extremely advantageous.

[Brief description of the drawings]

FIG. 1 is a block diagram of a deflection circuit according to one embodiment of the present invention.

FIG. 2 is a diagram showing a crosstalk component of a horizontal deflection current and a round-trip difference thereof.

FIG. 3 is a diagram showing a round-trip difference and a correction waveform thereof.

FIG. 4 is a schematic diagram after correction.

FIG. 5 is a schematic diagram of correction when a correction waveform has a phase shift;

FIG. 6 is a schematic diagram of an ideal bidirectional deflection.

FIG. 7 is a schematic diagram of actual bidirectional deflection.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Horizontal deflection circuit 2 Vertical deflection circuit 3 Horizontal deflection coil 4 Vertical deflection coil 5 Current-voltage conversion circuit 6 Forward rotation circuit 7 Inversion circuit 8 Switching circuit 9 Amplitude adjustment circuit 10 Transformer 11 Crosstalk component 12 Basic waveform 13 Difference 14 Correction waveform 15 Corrected waveform 16 Delayed corrected waveform 17 Midpoint

Claims (6)

[Claims] 1. A horizontal deflection circuit and a vertical deflection circuit for controlling a horizontal deflection coil and a vertical deflection coil, respectively.
The horizontal deflection circuit has a reciprocating horizontal scanning period by generating a symmetrical output current of a sine waveform approximation, in a bidirectional deflection television receiver for displaying an image also in the reciprocating horizontal scanning period, A correction circuit that cancels a reciprocal difference of the crosstalk component using a correction current extracted from an output current of the horizontal deflection circuit,
A deflection circuit for removing scanning distortion caused by crosstalk between the horizontal deflection coil and the vertical deflection coil. 2. The deflection circuit according to claim 1, further comprising a correction circuit configured to superimpose the correction current on a current flowing through the vertical deflection coil. 3. The deflection circuit according to claim 1, further comprising a correction circuit for applying the correction current to an auxiliary coil. 4. The deflection circuit according to claim 1, further comprising an amplitude adjustment circuit for adjusting the amplitude of the correction current. 5. A circuit according to claim 1, further comprising a circuit capable of selecting either a polarity inversion or a normal waveform of said correction current.
The deflection circuit according to claim 1. 6. A television receiver comprising the deflection circuit according to claim 1. Description: