JPH05308659A - Chrominance signal processor - Google Patents

Abstract

PURPOSE:To prevent the large deflection of the output signal of an LPF, which smooths the output signal of a phase comparator, even just after inversion of a color array and to suppress the hue variance and color disappearance by correcting the inversion of the color array. CONSTITUTION:When a reproducing head is moved to an adjacent track at the time of special reproducing, a comb line filter is switched to a low pass filter LPF 23 by a switch circuit 7 if the color array is inverted. The comb line filter 6 is switched to the LPF 23 by the occurrence of inversion of the color array. Consequently, the continuity of the color array is not lost because a signal obtained by inverting the hue of the output signal of the comb line filter 6 is outputted from the LPF 23, and the output of a phase comparator 20 and the output of a correcting circuit 18 are kept mutually cancelled, and the large deflection of the output signal of an LPF 17 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color signal processing device in a VHS video tape recorder (hereinafter abbreviated as VTR) for recording / reproducing PAL color video signals.

[0002]

2. Description of the Related Art In recent years, with the increase in screen size of televisions, high-quality video sources are required. Also, due to the diversification of applications, higher image quality during special reproduction is required.

An example of color signal processing of a VHS type VTR for recording / reproducing a PAL type color signal will be described below with reference to the drawings.

FIG. 3 is a block diagram of a reproducing system for color signal processing of the conventional VHS-PAL system. In the figure, the reproduction signal input from the input terminal 1 is extracted as a low-pass conversion color signal in a low-pass filter (hereinafter abbreviated as LPF) 2. The low-pass conversion color signal is supplied to a balanced modulator (hereinafter abbreviated as BM) 4 whose amplitude is controlled by an automatic gain control circuit (hereinafter abbreviated as ACC) 3 so that the color burst signal has a constant level. The frequency is converted in the BM4, and a bandpass filter (hereinafter, BPF) is used.
5), unnecessary components generated at the time of balanced modulation are removed and a reproduced carrier signal is extracted. Next, the comb filter 6
At, the adjacent crosstalk component is removed and the signal is output from the output terminal 8 through the switch circuit 7. The output signal of the comb-shaped filter 6 is delayed by 1H in the delay line 24 for one horizontal scanning period (hereinafter, abbreviated as 1H) and supplied to the switch circuit 7. The switch circuit 7 is controlled by the control signal from the input terminal 9, but the output signal of the comb filter 6 is always selected during normal reproduction, and it is switched and used during special reproduction. The reason will be described below. Although the (RY) axis of the PAL-type carrier color signal is inverted every 1H, during special reproduction of a long-time recording tape,
Inversion of the polarity of the (RY) axis may be irregular. Hereinafter, this state is referred to as color array inversion. If the color arrangement is reversed, the color demodulation circuit of the TV malfunctions and the color disappears. In order to correct this, when the color array is inverted, a signal delayed by 1H is output to correct the color array inversion. The above correction is performed by the 1H delay line 24, the switch circuit 7, and the control signal input terminal 8.

The phase comparator 20 compares the phase of the color burst signal of the carrier color signal output from the comb filter 6 with the reference signal from the reference signal oscillator 11. The error signal passes through the adder 19 and the LPF 17 and then 32.
A voltage controlled oscillator (hereinafter, abbreviated as VCO) 15 having a horizontal scanning frequency (hereinafter, abbreviated as f _H ) of 1 time is controlled. The fluctuation component for each 1H included in the error signal from the phase comparator 20 is canceled by supplying the output signal from the correction circuit 18 to the adder 19. The correction circuit 18 outputs a signal that is inverted every 1H, but when the polarity of the output signal is inverted, the variation component for each 1H is not canceled and increased, so that the waveform of the output signal of the LPF 17 is large. Become. The error detector 16 detects the increased output signal of the LPF 17 and outputs a control signal for inverting the polarity of the output signal of the correction circuit 18. Well 321f _H
The oscillation frequency of the VCO 15 is divided by 1/8 in the 1/8 divider circuit 14, and four output signals having different phases by 90 degrees are supplied to the selection circuit 13. In the selection circuit 13, VHS
According to the standard, one of the four output signals from the 1/8 frequency dividing circuit 14 is selected and supplied to the balanced modulation circuit 12. The balanced modulation circuit 12 carries out balanced modulation with the reference signal from the reference oscillator 11, and the BPF 10 removes unnecessary components to use as a carrier of the balanced modulator 4. As described above, the phase fluctuation that occurs during reproduction is corrected.

Here, a case where the color array is reversed when the reproducing head moves to an adjacent track during special reproduction will be described. FIG. 4 is a vector diagram of the color burst signal output from the comb filter 6 and the 1H delay line 24.
The vector diagram of the color burst signal output from the output, the waveform of the DC component of the output signal of the phase comparator 20 (hereinafter abbreviated as DC), the waveform of the output signal of the correction circuit 18, and the waveform of the output signal of the LPF 17 for each 1H. When the color array inversion occurs in the dotted line portion, the switch circuit 7 switches the selection from the comb filter to the 1H delay line 24. Alternatively, the 1H delay line 24 is switched to the comb filter 6. Here, the case of switching from the comb filter 6 to the 1H delay line 24 will be considered. When the color array inversion occurs, the comb filter 6 is switched to the 1H delay line 24. At this time, the polarity of the phase inversion for each 1H is switched, the polarity is inverted in 1H immediately after, and the original polarity is returned after 2H.

[0007]

However, in the above configuration, the output signal of the LPF 17 largely fluctuates during the 1H period immediately after the color array inversion occurs, and the pull-in for the phase variation is delayed. Therefore, when the color array is inverted immediately after the noise bar during special reproduction in the long-time mode, there is a problem in that hue variation and color disappearance occur. Further, since the 1H delay line is required, it has been difficult to rationalize by making it into an integrated circuit.

The present invention solves the above problems, and an object of the present invention is to provide a color signal processing device which is capable of suppressing hue variation and color disappearance even when color array inversion occurs and which is suitable for integration into an integrated circuit. I am trying.

[0009]

In order to achieve the above object, the present invention provides a comb filter for removing adjacent crosstalk components during reproduction, and a balanced modulation for inverting the phase of the output signal of the comb filter. , A multiplier for multiplying the output of the reference oscillator, a low-pass filter for removing unnecessary components of balanced modulation, and an output signal of the comb filter and LP
A switch circuit for inputting the output signal of F and selecting one,
A phase comparator for comparing the phase of a reference signal from a reference oscillator and a color burst signal of a color signal output from a switch circuit in order to correct a phase fluctuation generated during reproduction, and P
The color signal processing device includes a correction circuit that generates a signal that corrects a phase fluctuation for each horizontal scanning period that occurs in the AL system, and an adder that adds the correction signal to the output signal of the phase comparator.

[0010]

According to the present invention, by the above configuration, the output signal of the LPF for smoothing the output signal of the phase comparator is stable and stable even immediately after the color array inversion occurs by performing the color array inversion correction. Since the phase variation can be corrected, the hue variation and color disappearance can be suppressed. In addition, it was necessary 1
The H delay line becomes unnecessary.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A color signal processing apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows VHS- in one embodiment of the present invention.
It is a block diagram of a reproduction system of PAL system color signal processing.
In the figure, the reproduction signal input from the input terminal 1 is L
The low-pass conversion color signal is taken out in PF2. The amplitude of the low-pass conversion color signal is controlled by the ACC 3 so that the color burst signal has a constant level and is supplied to the BM 4. The frequency is converted in the BM4, and the unnecessary component generated during the balanced modulation is removed in the BPF5 to extract the reproduced carrier color signal. Next, the comb filter 6 removes the adjacent crosstalk component, and passes through the switch circuit 7 and is output from the output terminal 8. On the other hand, the output signal of the comb-shaped filter 6 is balanced-modulated in the BM 22 with the signal obtained by doubling the output signal of the reference oscillator as a carrier, and the LPF 23.
The unnecessary components are removed in step S3 and then supplied to the switch circuit 7. The switch circuit 7 is controlled by the control signal from the input terminal 9, but always selects the output signal of the comb filter 6 during normal reproduction. It will be used by switching during special playback.

The phase comparator 20 compares the phase of the color burst signal of the carrier color signal output from the comb filter 6 with the reference signal from the reference signal oscillator 11. The error signal passes through the adder 19 and the LPF 17 and then 32.
A voltage controlled oscillator (hereinafter, abbreviated as VCO) 15 having a horizontal scanning frequency (hereinafter, abbreviated as f _H ) of 1 time is controlled. The fluctuation component for each 1H included in the error signal from the phase comparator 20 is canceled by supplying the output signal from the correction circuit 18 to the adder 19. The correction circuit 18 outputs a signal that is inverted every 1H, but when the polarity of the output signal is inverted, the variation component for each 1H is not canceled and increased, so that the waveform of the output signal of the LPF 17 is large. Become. The error detector 16 detects the increased output signal of the LPF 17 and outputs a control signal for inverting the polarity of the output signal of the correction circuit 18. Well 321f _H
The oscillation frequency of the VCO 15 is divided by 1/8 in the 1/8 divider circuit 14, and four output signals having different phases by 90 degrees are supplied to the selection circuit 13. In the selection circuit 13, VHS
According to the standard, one of the four output signals from the 1/8 frequency dividing circuit 14 is selected and supplied to the balanced modulation circuit 12. The balanced modulation circuit 12 carries out balanced modulation with the reference signal from the reference oscillator 11, the BPF 10 removes unnecessary components, and the carrier is used as the carrier of the balanced modulator 4. As described above, the phase fluctuation that occurs during reproduction is corrected.

Here, the case where the color array is inverted when the reproducing head moves to an adjacent track during special reproduction will be described. FIG. 2 is a vector diagram of the color burst signal output from the comb filter 6, LPF2.
3 is a vector diagram of the color burst signal output from the signal No. 3, the waveform of the DC component of the output signal of the phase comparator 20 (hereinafter referred to as DC
Abbreviated), the waveform of the output signal of the correction circuit 18, the LPF 17
The waveform of the output signal is shown for each 1H, and when the color array inversion occurs in the dotted line portion, the switch circuit 7 switches the selection from the comb filter to the LPF 23. Alternatively, the LPF 23 is switched to the comb filter 6. Here, the case of switching from the comb filter 6 to the LPF 23 will be considered. When the color array inversion occurs, the comb filter 6 is switched to the LPF 23. Since the LPF 23 outputs the output signal of the comb filter 6 and the signal whose hue is inverted, the continuity of the color arrangement is not lost, and the output of the phase comparator 20 and the output of the correction circuit 18 cancel each other. The output signal of the LPF 17 does not fluctuate greatly.

As described above, according to the color signal processing device of the embodiment of the present invention, the output signal of the LPF for smoothing the output signal of the phase comparator is suppressed and greatly stabilized even immediately after the inversion of the color arrangement occurs. Since the phase variation can be corrected, the hue variation and the color disappearance can be suppressed even when the color array inversion occurs, and the 1H delay line is unnecessary.

[0016]

As is clear from the above embodiments, according to the present invention, the output signal of the LPF for smoothing the output signal of the phase comparator is stable and stable even immediately after the inversion of the color array occurs. Since the phase variation can be corrected, the hue variation and the color disappearance can be suppressed even when the color array inversion occurs, and a good screen can be obtained. Further, since the 1H delay line is not required, it is possible to provide a color signal device which can be easily integrated into a circuit and can be greatly rationalized.

[Brief description of drawings]

FIG. 1 is a block diagram of a color signal processing device according to an embodiment of the present invention.

FIG. 2 is a vector diagram and output waveform of each block of the same embodiment.

FIG. 3 is a block diagram of a conventional color signal processing device array.

FIG. 4 is a vector diagram and output waveform of each conventional block.

[Explanation of symbols]

 2 LPF 3 ACC 4 Balanced modulator 6 Comb type filter 7 Switch circuit 18 Correction circuit 19 Adder 20 Phase comparator

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hirotsugu Nakayama 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A color signal processing device for frequency-converting and recording a carrier color signal in a low frequency range, and inversely converting it during reproduction, wherein the comb-shaped filter removes adjacent crosstalk components during reproduction, and the comb-shaped filter. A Heihei modulator for inverting the phase of the (R-Y) axis of the output signal of the filter, a multiplier for multiplying the output of the reference oscillator, and a low-pass filter for removing unnecessary components of the balanced modulation, A switch circuit for inputting the output signal of the comb-shaped filter and the output signal of the low-pass filter and selecting and outputting one of them, a reference signal from a reference oscillator for correcting the phase fluctuation generated at the time of reproduction, and the output from the switch circuit. A phase comparator for comparing the phases of the color burst signals of the color signals, a correction circuit for generating a signal for correcting the phase fluctuation for each horizontal scanning period generated in the PAL system, Color signal processing apparatus characterized by comprising an adder for adding the correction signal to the output signal of the phase comparator.