JPS608677B2 - Color video signal converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a signal conversion device for use in transmitting, storing and reproducing color video signals.

When the television signal shown in the frequency diagram in Figure 1a is recorded on a disc-shaped recording medium in the form of an angle modulation signal, there are limitations on the recording density of the recording medium and problems due to interference between the carrier color signal and the carrier signal. Due to reasons such as the need to minimize the amount of noise, an embedded subcarrier format signal (hereinafter referred to as A method of converting color image signals in video disc devices has been proposed in which a veridical chroma signal (referred to as a veridical chroma signal) is generated, the veridical chroma signal is angularly modulated, and then recorded and reproduced on a disc-shaped recording medium using an appropriate method.

FIG. 2 is a block diagram showing an example of the color image signal conversion device. The signal that has entered the input mode 1 of the NTSC color image signal is supplied to three blocks: an LPF 2, a delay circuit 3, and a synchronous separation circuit 4. The respective outputs of the LPF 2 and the delay circuit 3 are added to the subtraction circuit 8,
Here, by matching the delay times of circuits 2 and 3, an HPF is constructed. The output signal of the subtraction circuit 5 is directly applied to the addition circuit 6 and the subtraction circuit 7, and at the same time
After passing through the horizontal scanning period (IH) delay circuit 8, it is applied to the addition circuit 6 and the subtraction circuit 7, and in the addition circuit 6, the Y-shaped comb filter output signal is also applied to the subtraction circuit hole. obtained a C-shaped comb filter output signal. The output signal of the adder circuit 6 is added to another adder circuit 9, where the signals from the LPF 2 are added together to create a luminance signal having a full range. The output signal of the adder circuit 9 is applied to the adder circuit 12 through a delay circuit 11 for aligning the phase with the chroma signal after passing through an LPFIO having a cutoff frequency that should be limited to a band suitable for the video disc system to be adopted. The output signal of the subtraction circuit 7 is approximately 3.5 Isohata Z±0. Owns the castle of the enthroned Z. After passing through the BPF 1 3, the signal applied to the modulation circuit 14 and the burst gate circuit 15 is gated by the burst gate pulse created by the synchronous separation circuit 4, and then sent to the APC oscillation circuit 1.
6 to generate a continuous signal that is now locked to the phase of the color carrier signal of the input NTSC signal. AP
The output signal of the C oscillation circuit 16 is applied to a multiplier circuit 17, where, for example, if the color carrier frequency frequency of the Berritt chroma signal is selected to be fH/2×195 (however, fw horizontal synchronization signal frequency multiplication Beef X (9 states 55) = 6pm
so that a signal of 50 frequencies is obtained, i.e. 10/7
The multiplication rate is determined so that it is multiplied. The output signal of the multiplier circuit 17 is applied to the modulation circuit 14, where the BPF 13
After modulating the chroma signal from LPF (or BP
F) In step 18, unnecessary components are removed, an adder circuit 12 is added, and the luminance signal component from the delay circuit 11 is added, after which the signal is output to the buried chroma signal output terminal 19. This output terminal 1
The spectral distribution of the signal output to 9 is as shown in FIG. 1b. In the above conversion device, in order to minimize the reduction in vertical resolution due to the comb-shaped filter configuration, the band that makes up the comb-shaped filter is set in the band of the output signal of the subtraction circuit 5 (i.e., the HPF output signal). It is restricted.
Here, the signal band of the subtracting circuit 5 is determined by the band of the LPF 2, and it goes without saying that the cutoff frequency of the LPF 2 should be as high as possible in order to reduce the drop in vertical resolution. Since it is necessary to superimpose the carrier color signal on the middle frequency band of the luminance signal, it is necessary to remove the odd vertical component of the luminance signal component in the band to be superimposed.

Therefore, this belt castle also has a comb-shaped structure.
The cut-off frequency of the LPF 2 should be set to approximately MH2 or lower, assuming that the minute value is XI95.

FIG. 3 is a block diagram showing an example of a reproducing circuit in a video disc device for reproducing the verit chroma signal shown in FIG. 2 to the original television signal (NTSC format). The signal input to the verit chroma signal input terminal 201 is applied to the BPF 21, where the signal of approximately the sum of the carrier color signal band "S'±0.Rule 5 z)" is extracted,
In addition to the balanced modulation circuit 22, here a voltage suppressed oscillator generates a signal having a frequency that is the sum of a signal locked to the phase of the color carrier signal of the input verit chroma signal and a signal having a stable oscillation frequency n. After being balanced modulated by the signal from VC023, the difference signal component, approximately 3
．． A signal in a band of 0.8 MHz relative to 58 MHz is extracted by a BPF 24 and applied to a C-shaped comb filter 27 comprising an IH delay circuit 25 and a subtraction circuit 26. In this C-shaped comb-shaped filter 27, the luminance signal component included in that band is removed and only the chroma signal component is taken out, and then added to the balanced modulation circuit 28, where it passes through the variable phase shifter 29. It is balanced modulated by the signal from VC023, and the difference signal component is removed by the BPF 4, thereby converting it back into the original chroma signal of the band. The output signal of the BPF 40 is added to the adder circuit 30', where it is mixed with the veridical chroma signal from the input terminal 20 which has passed through the delay circuit 31 for matching the phase, and the chroma signal component in the veritable chroma signal is removed to adjust the luminance. The output signal of the adder circuit 30, which extracts only the signal component, is added to another adder circuit 32,
Here, the chroma signal from the C-shaped comb filter 27 which has passed through the delay circuit 33 is added to the NTSC format signal output terminal 34.
is output to. FIG. 4 shows the horizontal scanning line configuration when using the color video signal converter and video disc playback device described above. In FIG. 4, for example, when focusing on the nth line of the original signal, The line of the output signal of the reproducing device corresponding to
4 and the (n-1)th line is 1/4, forming one line.

That is, while the main signal is the (n-1)th line of the original signal, the line in which the comb-shaped filter is not formed is the nth line of the original signal. For this reason, there is a drawback that the reproduced image becomes blurred, especially in the video portion where the vertical correlation is low. It is an object of the present invention to eliminate such drawbacks and to improve the deterioration of image quality in the vertical direction due to the comb-shaped filter configuration.

FIG. 5 is a block diagram showing one embodiment of the present invention. All flocks common to Figure 2 are numbered the same. 5 differs from FIG. 2 in that an I-day delay circuit 35 is inserted between the LPF 2 and the adder circuit 9. In other words, the LPF 2 delays the signal in the band that does not have a comb-shaped filter configuration and is delayed by I days, and the signal is added to the adder circuit 6.
is added to the Y-comb filter output signal from the Y-comb filter. By doing this, the line configuration of the output signal of the reproducing device corresponding to the nth line of the original IJ original signal shown in FIG. n-1), and the main line (
Matches n-1)th. Therefore, it is possible to improve the defects particularly in the video portion where the vertical correlation is low, and the reproduced image quality can be significantly improved. FIG. 6 is a block diagram of a color video conversion apparatus showing another embodiment of the present invention.
As in the case of FIG. 6, blocks common to those in FIG. 2 are given the same numbers. The I-day delay circuits 8 and 35 used in the embodiment of FIG. 5 have good characteristics and require very expensive circuits, but in the embodiment shown in FIG.
Since it is necessary to use two circuits (1 and 35), the entire device becomes expensive. The embodiment shown in FIG. 6 also improves this problem. The difference from the embodiment shown in FIG. 5 is that the I-day delay circuit is omitted. That is, the signal input to the input terminal 1 passes through the IH delay circuit 36 and is then applied to the HPF circuit consisting of the LPF 37, the delay circuit 38, and the subtraction circuit 39. The characteristics of this HPF circuit are approximately the same as those of the HPF circuit composed of blocks 2, 3, and 5. In this case, the output signal of the subtraction circuit 39 is a high frequency band signal delayed by I days, and is equivalent to the output signal of the IH delay circuit 8 in FIG. Therefore, subtraction circuit 3
By adding the output signals of 9 to the addition circuit 6 and the subtraction circuit 7, respectively, and mixing them with the signal from the subtraction circuit 5, a Y-shaped comb filter output signal and a C-shaped comb filter output signal are obtained as in the case of FIG. can be obtained. On the other hand, the signal from the LPF 37 applied to the adder circuit 9 is a low frequency component delayed by I days. Therefore, not only the operational effect is the same as that of the embodiment shown in FIG. 5, but also one expensive I-day delay circuit can be omitted, making it possible to provide an inexpensive device. As described above, according to the present invention, it is possible to transmit, record and reproduce color video signals using the vertical chroma signal system while reducing the reduction in vertical resolution, and it is possible to transmit, record and reproduce color video signals using the vertical chroma signal system, and it is possible to reduce the reduction in vertical resolution. It can be effectively used for John telephones, etc.

[Brief explanation of the drawing]

Figure 1 is a frequency diagram of a color television signal. FIG. 2 is a block diagram showing an example of a conventional color video signal conversion device. FIG. 3 is a block diagram showing an example of a playback circuit in a conventional video disc device. FIG. 4 is a diagram showing the configuration of a horizontal scanning line in a converting device and a reproducing device when a comb-shaped filter configuration is adopted. FIG. 5 is a block diagram showing an embodiment of a color video signal conversion device according to the present invention. 6th
The figure is a block diagram showing another embodiment of the color video signal conversion device according to the present invention. 1...Input terminal, 2
,10,18,37...LPF,3,1 1,38
...Delay circuit, 5, 7, 39...Subtractor, 8,
35.36...I day delay circuit, 13...BFF
, 14...Modulation circuit. Section 1 Figure Leopard 2 Figure Hoko 4 Figure Scales 6 Figure 3 Box Tsutomu 5 Figure

Claims (1)

[Scope of Claims] 1. Separating means for separating a color video signal into a first signal component occupying a first frequency band and a second signal component occupying a higher second frequency band, and the separating means a first comb-shaped filter means for separating and extracting a spectral component of a frequency corresponding to an odd multiple of 1/2 of the horizontal scanning frequency from the second signal component occupying the second frequency band separated by; and the separating means 1/1 of the horizontal scanning frequency from the second signal component occupying the second frequency band separated by
After limiting the chrominance signal in the output signal of the second comb-shaped filter means for separating and extracting spectral components of frequencies corresponding to even multiples of 2 and the first comb-shaped filter means to a necessary band, the chrominance signal is a frequency converting means for converting into a chrominance signal having a frequency lower than that of the signal and existing within the second frequency band; and a first signal occupying the first frequency band separated by the separating means. A color video signal conversion device comprising a delay means for delaying a component by one horizontal scanning time, and means for mixing an output of the delay means, an output of the frequency conversion means, and each output of the second comb filter means. 2. After passing through a delay means for delaying the color video signal by one horizontal scanning time, the output signal of the delay means is divided into a first signal component occupying a first frequency band and a second signal component occupying a higher second frequency band. a first separating means for separating a signal component occupying the first frequency band from the color video signal;
1/1 of the horizontal scanning frequency using the signal components of the two second frequency bands separated by the second separating means.
A first comb-shaped filter means for separating and extracting spectrum components having a frequency equivalent to an odd multiple of 2, and a second comb-shaped filter means for separating and extracting a spectrum component having a frequency corresponding to an even multiple of 1/2 of the horizontal scanning frequency. and after limiting the chrominance signal in the output signal of the first comb-shaped filter means to a required band, the chrominance signal in a band having a lower frequency than the chrominance signal and existing within the second frequency band. A color image comprising a frequency conversion means for converting into a signal, and a mixing means for mixing the output of the frequency conversion means, the output of the second comb filter means, and the first signal component signal of the second separation means. Signal device.