JPH10164384A - Television receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a television receiver in which the interval of scanning lines is always kept excellent even when there is local ununiformity in intervals of scanning lies due to fluctuation in lightness or the like. SOLUTION: A phase comparator circuit 8 compares the phase of a vertical synchronizing signal with the phase of an output voltage outputted from a vertical deflection output circuit 5. An auxiliary drive pulse generating circuit 9 generates an auxiliary drive pulse. An amplitude adjustment circuit 10 adjusts the amplitude of the auxiliary drive pulse based on comparison result by the phase comparator circuit 8. An auxiliary vertical output circuit 11 supplies a current to an auxiliary vertical deflection coil 12 by the received auxiliary drive pulse to move scanning lines vertically within the range of one line interval.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver for displaying an image by raster scanning, and more particularly to a television receiver capable of improving non-uniformity of scanning line intervals.

[0002]

2. Description of the Related Art At present, in the NTSC standard television system in Japan, interlaced scanning of 525 scanning lines is performed. For this reason, cathode ray tubes (CRTs)
The larger the is, the wider the scanning line interval becomes, and individual scanning lines become conspicuous. At this time, if the scanning lines are uneven on the screen, they appear as luminance changes. In order to improve this, there is a television receiver in which the phase of an incoming synchronization signal is adjusted using a phase adjustment circuit to adjust the scanning line interval.

FIG. 4 is a block diagram showing an example of a conventional television receiver. Referring to FIG.
Separates the vertical sync signal. The phase adjustment circuit 2 adjusts the phase of the vertical synchronization signal. The vertical oscillation circuit 3 oscillates at a frequency synchronized with the input vertical synchronization signal. The vertical drive circuit 4 outputs a sawtooth signal using the oscillation waveform from the vertical oscillation circuit 3. The vertical output circuit 5 amplifies the sawtooth signal and supplies it to a vertical deflection coil 7 mounted on the CRT 6. As a result, a vertical deflection current, which is a sawtooth current of a vertical cycle, flows through the vertical deflection coil 7,
The electron beam of the CRT 6 is deflected in the vertical direction.

[0004]

However, in recent years, CR
The screen of T6 has become larger and wider. Wide television receivers are equipped with a zoom (cinema) mode in which a letter-box size image is vertically enlarged and projected by a vertical deflection circuit, and the scanning line interval has become particularly noticeable. In the above-described conventional television receiver, it is necessary to predict the disturbance of the phase of the vertical deflection current due to the horizontal deflection pulse in the vertical output circuit 5 and correct the phase by the phase adjustment circuit 2 in advance. Accordingly, the scanning line interval can be corrected by the phase adjustment circuit 2 for the constant deviation of the scanning line interval. However, the phase variation due to local brightness fluctuation of the screen, the vertical output At present, it is impossible to cope with a shift in the scanning line interval caused by a change in the amount of phase disturbance due to the temperature characteristic of the circuit 5.

FIG. 5A shows a normal raster scan, and FIG. 5B shows a state in which scanning line intervals are not uniform. 5A and 5B, a solid line indicates a scanning line of the first field, and a broken line indicates a scanning line of the second field. In a conventional television receiver, FIG.
As shown in (B), for example, even if the scanning line of the second field is displaced from the original position, the unevenness of the scanning line interval cannot be eliminated as described above, and this appears as a luminance difference. This was a cause of image quality deterioration. The present invention has been made in view of such a problem, and a television receiver that can always maintain a good scanning line interval even when there is a local uneven scanning line interval due to brightness fluctuation or the like. The purpose is to provide.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present invention provides a synchronization separation circuit (1) for separating a vertical synchronization signal from an incoming video signal, and a synchronization separation circuit. A vertical deflection circuit (3 to 5, which vertically deflects the electron beam using the separated vertical synchronizing signal.
7) a phase comparison circuit (8) for comparing the phase of the vertical synchronization signal with the output voltage output from the vertical deflection circuit; and an electron beam using the vertical synchronization signal. An auxiliary vertical deflection circuit (9, 11, 12) for performing an auxiliary vertical deflection, and an adjustment circuit (10) for adjusting the auxiliary vertical deflection by the auxiliary vertical deflection circuit based on the comparison result of the phase comparison circuit. It is intended to provide a television receiver characterized in that it is configured.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a television receiver according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram showing one embodiment of a television receiver of the present invention,
FIG. 2 is a waveform diagram showing an auxiliary drive pulse used in the television receiver of the present invention, and FIG. 3 is a diagram for explaining the operation of the television receiver of the present invention. In FIG. 1, the same parts as those in FIG. 4 are denoted by the same reference numerals.

In FIG. 1, a synchronization separation circuit 1 separates a horizontal synchronization signal and a vertical synchronization signal. The horizontal synchronization signal is supplied to a horizontal deflection circuit (not shown). The vertical synchronizing signal is input to the vertical oscillation circuit 3. The vertical oscillation circuit 3 oscillates at a frequency synchronized with the input vertical synchronization signal. The vertical drive circuit 4 outputs a sawtooth signal using the oscillation waveform from the vertical oscillation circuit 3. The vertical output circuit 5 amplifies the sawtooth signal and supplies it to a vertical deflection coil 7 mounted on the CRT 6. As a result, a vertical deflection current, which is a sawtooth current of a vertical cycle, flows through the vertical deflection coil 7,
The electron beam of the CRT 6 is deflected in the vertical direction. In addition,
Vertical oscillation circuit 3 to vertical output circuit 5 and vertical deflection coil 7
Constitutes a vertical deflection circuit.

Further, the phase comparison circuit 8 compares the phase of the vertical synchronization signal output from the synchronization separation circuit 1 with the output pulse voltage of the vertical deflection cycle output from the vertical output circuit 5, and detects the comparison result. The signal is supplied to the amplitude adjustment circuit 10. The vertical synchronization signal output from the synchronization separation circuit 1 is also input to the auxiliary drive pulse generation circuit 9, and the auxiliary drive pulse generation circuit 9 generates an auxiliary drive pulse that is a rectangular wave as shown in FIG. This auxiliary drive pulse is input to the amplitude adjustment circuit 10. The amplitude adjustment circuit 10 adjusts the amplitude of the auxiliary drive pulse based on the detection signal input from the phase comparison circuit 8.

The auxiliary drive pulse output from the amplitude adjustment circuit 10 is input to the auxiliary vertical output circuit 11. The auxiliary vertical output circuit 11 supplies a current to the auxiliary vertical deflection coil 12 and moves the scanning line of the field up and down within a range of one line interval. The auxiliary drive pulse generating circuit 9, auxiliary vertical output circuit 11, and auxiliary vertical deflection coil 12 constitute an auxiliary vertical deflection circuit. FIG. 3 shows a case where the scanning line intervals are non-uniform as shown in FIG.
A state in which the scanning line is moved within a range of one line interval so as to be in a normal state as shown in FIG. The scanning line indicated by the thin broken line is moved to the position indicated by the thick broken line, whereby the scanning line interval becomes uniform.

As a result, the deviation of the scanning line interval due to the vertical output circuit 5 can be corrected, and the scanning line interval can always be kept constant. In this embodiment, as the most preferable embodiment of the auxiliary vertical deflection circuit, the scanning line interval is adjusted by the auxiliary vertical deflection coil 12, so that precise alignment can be performed.

[0012]

As described above in detail, the television receiver according to the present invention comprises a synchronization separation circuit for separating a vertical synchronization signal from an incoming video signal, and a vertical synchronization signal separated by the synchronization separation circuit. In a television receiver having a vertical deflection circuit for vertically deflecting an electron beam by using a phase comparison circuit for comparing the phase of a vertical synchronization signal with an output voltage output from the vertical deflection circuit, and a vertical synchronization signal. Since it is equipped with an auxiliary vertical deflection circuit that uses the auxiliary vertical deflection circuit to make the auxiliary vertical deflection of the electron beam, and an adjustment circuit that adjusts the auxiliary vertical deflection by the auxiliary vertical deflection circuit based on the comparison result of the phase comparison circuit, Therefore, even if there is local unevenness in the scanning line interval due to the above, the scanning line interval can always be kept good. Therefore, the quality of the projected image can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a waveform diagram showing an auxiliary drive pulse used in the present invention.

FIG. 3 is a diagram for explaining the operation of the television receiver of the present invention.

FIG. 4 is a block diagram showing a conventional example.

FIG. 5 is a diagram for explaining a problem of a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sync separation circuit 3 vertical oscillation circuit 4 vertical drive circuit 5 vertical output circuit 6 cathode ray tube 7 vertical deflection coil 8 phase comparison circuit 9 auxiliary drive pulse generation circuit 10 amplitude adjustment circuit 11 auxiliary vertical output circuit 12 auxiliary vertical deflection coil

Claims (1)

[Claims] A synchronization circuit for separating a vertical synchronization signal from an incoming video signal; and a vertical deflection circuit for vertically deflecting an electron beam using the vertical synchronization signal separated by the synchronization separation circuit. In a television receiver, a phase comparison circuit for comparing the phase of the vertical synchronization signal with an output voltage output from the vertical deflection circuit, and an auxiliary vertical deflection circuit for auxiliary vertical deflection of an electron beam using the vertical synchronization signal And a adjusting circuit for adjusting auxiliary vertical deflection by the auxiliary vertical deflection circuit based on a comparison result of the phase comparison circuit.