JPS603295A - Color video signal processing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of processing color video signals that can be used in video tape recorders and the like.

Conventional configurations and their problems Currently, consumer color videotape recorders (VTRs), which are widely used in general, are capable of recording only 18 degrees, 18 degrees, and 18 degrees. 11. The carrier color signal is converted into an FM signal that occupies the fF band side, and the carrier color signal is frequency-converted to the lower frequency side of the FM luminance signal, and the carrier color signal is frequency-converted to the lower frequency side of the FM luminance signal.
A frequency multiplexed signal with a carrier color signal is recorded on the magnetic tape. At the time of reproduction, the FM luminance signal and the low frequency converted carrier color signal are separated from the reproduced multiplexed signal, the original luminance signal is demodulated from the FM luminance signal, and the low frequency converted carrier color signal is demodulated from the FM luminance signal. The color signal is also frequency converted to the original frequency band. Color signal processing in such a recording method is quite complicated, and this process requires 1 dVTH.
``Simplifying the circuit of the circuit'' was one of the problems. Especially in recent consumer VTRs, card bandless azimuth recording is adopted to achieve high recording density, but in this case, in order to prevent crosstalk between adjacent tracks for color signals, the The configuration is such that the phase of the carrier color signal is changed and recorded, the phase is returned for each line during reproduction, and a 1H comb filter is arranged on the reproduction output side. Such processing not only complicates the circuit, but also requires a glass delay line that constitutes the comb filter, which poses a problem in terms of miniaturization.

OBJECTS OF THE INVENTION An object of the present invention is to simplify the color signal processing circuit of a VTR and to make it possible to incorporate it into an LSI by using a configuration that does not use a glass delay line, thereby reducing the size and cost of the circuit. The object of the present invention is to provide a processing method.

Structure of the Invention The color video signal processing method of the present invention applies a phase change opposite to the field and line unit phase change received on the recording side to the low-frequency conversion carrier color signal, and then combs it. This allows the signal to be passed through a comb-shaped filter.This allows the low frequency conversion carrier color signal to be processed in the frequency range 1. This makes it easy to manufacture semiconductors using the technology, making it possible to miniaturize circuits and reduce costs.

DESCRIPTION OF EMBODIMENTS Hereinafter, non-inventive embodiments will be described in comparison with conventional examples.

Figure 1 shows the FJf of a general consumer azimuth recording VTR.
FIG. 2 is a schematic configuration diagram of a raw side color belief color value theory system. (Actually, a time axis fluctuation removal circuit is involved, but the explanation will be complicated, so it is omitted.)
I'm here. ) The color video signal produced by the magnetic tape and rotating head is divided into a reproduced low-thorn-converted carrier color signal A by a low-pass filter, and is applied to a frequency converter 1. A head switching signal B from the rotating cylinder and a horizontal synchronizing signal C extracted from the reproduced color video signal q are applied to a phase converter 2. The phase converter 2 generates a local oscillation frequency for frequency conversion with the reproduced low frequency conversion carrier color signal signal, and changes the phase of each line by the head switching signal and the horizontal synchronization signal. The phase change for each line is controlled so that the phase change is in the opposite direction to the phase change that occurs during recording with respect to the conveyed color signal. Frequency converter 1
and phase converter 2 and bandpass filter (BPF) 3
By reproducing the low frequency conversion carrier color signal the person is returned to the high frequency ft, N
In the TSc method, the color signal is centered at 3.58 MHz.

The color signal returned to 3.58MHz is filtered by a comb filter to remove crosstalk components from adjacent trunks.
Outputs the transport color signal. In this way, the conventional reproduction side color signal processing system changes the phase of the low-pass converted carrier color signal during frequency conversion, returns it to the carrier color signal, and then passes it through a comb filter.

FIG. 2 is a schematic diagram of a reproduction side color signal processing system showing an embodiment of the present invention. Reproduction low-pass conversion carrier color signal person is phase converter 5. The signal passes through a comb filter 6, a frequency converter 7 coupled with a local oscillator 8, and a bandpass filter 9 in this order, and is converted into a carrier color signal. The difference from the conventional example shown in FIG. 1 is that before performing frequency conversion, a phase change is applied and the signal is passed through a comb filter. The phase converter 5 applies a predetermined phase change to the inputted low-frequency conversion carrier color signal line by a head switching signal B and a horizontal synchronizing signal C in a direction opposite to that during recording. The comb filter serves to remove crosstalk components from adjacent trunks from the phase-changed low-pass transformed carrier color signal. The principle by which adjacent crosstalk components are removed by the comb filter 6 by changing the low-pass converted carrier color signal will be explained with reference to FIGS. 3 and 4. FIG.

FIG. 3 is a diagram showing the phase relationship of low frequency conversion carrier color signals for the VH3H3 system. During recording, the phase of track A is shifted in the direction of advancing by 90 lines, and (
It changes as shown by the arrow in a).

If 1 reline 1 is 0, then on line 2 it advances 98, on line 3 it advances 180, on line 4 it advances 27 g, and on line 5 it returns to the same state as line 1, and the same changes are repeated thereafter. In the B track, the phase is shifted in the direction of delay by 90 for each line and changes as shown by the arrow in (b). During reproduction, the phase shifter 6 applies a phase shift in the opposite direction to that during recording, so that the reproduction output of track A, for example, has its phase returned to its original state as shown in (C). Generally, when reproducing the A track, a portion of the B trunk signal is also picked up as adjacent crosstalk, so this is shown by a broken arrow. The phase (b) of adjacent crosstalk components is 9
The phase is shifted in the direction of 0 lag. (d) is (0
) is delayed by one line (usually called 1H). (e) is the sum of the reproduced output (C) of the human track and the signal delayed by 1H (d). As a result, the adjacent crosstalk components indicated by the broken lines are in opposite phases and cancel each other out, and A Only the track signal will be extracted.

Here, adding the signal (0) and (d) means passing it through a comb filter.In other words, the A track output (C) is expressed as a spectrum as shown in Figure 4 (a).VH3H3 The low frequency conversion carrier color signal used in the system is 40 fH.
It has a band of approximately ±500 KHz centered around (fH is the line frequency), and has a distribution with a peak for each fH.

On the other hand, since the phase of the crosstalk component is reversed for each line as shown by the broken line in Figure 3 (C),
The spectrum falls into the f□ interval. Therefore, if the signal is passed through a Y-shaped comb filter having characteristics as shown in FIG. 4(b), the main signal for each f□ is extracted and the crosstalk component is removed. As mentioned above, after returning the phase shift to the adjacent crosstalk, the low-frequency conversion carrier color signal remains as it is, and the Y
It can be removed by passing it through a comb filter.

The low frequency converted carrier color signal from which adjacent crosstalk has been removed by the comb filter 6 is sent to a frequency converter 7° local oscillator 8. A predetermined band (NTSC
(3.58 MHz) to obtain a carrier color signal.

In the configuration shown in Fig. 2, the band used by the comb filter 6 is the low-pass conversion carrier color signal (ij: 629KH2±50 in the VH8 system).
0KHz) band is sufficient. Therefore, it is easy to use a semiconductor analog delay circuit such as a COD for the 1H delay circuit that is a component of the comb filter. In other words, 1H when returning to K 3.68 MHz as in the conventional example.
If COD were to be used for delay, a high clock frequency would be required and the number of COD stages would increase, making it difficult to implement in terms of performance and cost. In contrast, 1H at 629 KHz
To delay, a low clock frequency is required and the number of stages is small, which is advantageous in terms of performance and cost. In this way the second
In the illustrated embodiment, the comb filter can be easily constructed from a semiconductor such as COD, and the circuit can be easily miniaturized.

FIG. 6 is a block diagram of a reproduction side signal processing system showing another embodiment of the present invention. The reproduction low-pass conversion carrier color signal is converted into a digital color signal E by the AFiAD converter 10, the phase change is reflected in the phase converter 11, and the digital comb filter 1
2, the signal is returned to an analog signal by a DA converter 13, and restored to a carrier color signal by a frequency converter 14 coupled to a local oscillator 16 and a digital filter (BPF) 16. The difference from the embodiment of FIG. 2 is that the phase conversion and comb filter are performed on the digitized signal of the low-pass conversion carrier color signal. The phase converter 11 changes the phase of the digital signal exactly, and an example of its operation is shown in FIG. It is necessary to realize the advance and lag for each VH3H3 system 98. FIG. 6(g) is an input analog signal, which can be considered as a part of the low frequency conversion carrier color signal. (A) is the case where the phase shift is O, and each sample value of the input signal S1゜S2 + 33 + S4 + S5
+S6... is, for example, a 6-bit digital value. (The figure shows the state in which the converter is converted to analog.) The signal obtained by delaying the signal of 0) by 98 (advanced by 27♂) is (1), and this is @), and each sample This is achieved by delaying the value by one sample period (in this case, the sample frequency is four times the frequency of the low-pass conversion carrier color signal). The 9O lead (27♂ delay) signal is obtained by delaying each sample value of @) by one sample period and further inverting its analog polarity (for example, taking the complement for digital values). Although not shown, 18♂
This can be easily realized by making each sample value (leading or lagging) reverse polarity in an analog manner. in this way,
By delaying and inverting the sampled digital signal, the phase of the digital signal can be shifted. The configuration of the digital comb filter can be realized using a 1H digital memory and an adder. FIG. 7 shows an example of the configuration of a digital comb filter.

Input F is a digital value obtained by phase shifting the low frequency conversion carrier color signal, and this signal is sent to the 1H memory unit 17 and the adder 18.
added to. A digital signal delayed by 1H is also applied to the adder 18, and its output becomes a digital signal passed through a il'iY-type comb filter.

In this way, a comb filter can be easily realized using digital signals. In the embodiment shown in FIG. 6, since the phase conversion and comb filter are performed using digital signals, it is possible to realize the desired operation with better viscosity and without performance deterioration compared to the conventional analog method.

In particular, conventional comb filters use glass delay lines, and it has been difficult to obtain ideal comb characteristics due to various reasons such as variations in the delay time, spurious waves due to reflection, and fluctuations in frequency characteristics in the pass band. On the other hand, with a digital comb filter, an ideal comb filter can be easily obtained. In short, the AD converter 10 and the DA converter 13 only need to cover the band of the low-frequency conversion carrier color signal, and can be extremely small-scaled compared to processing in the 3.58 MHz band, for example.

In the above embodiment, the color signal processing of the VH8 system is mainly explained, but it should be noted that it can be implemented in exactly the same way for a system such as the β system, which does not use 9g for the phase shift and processes only with a 180° relationship. do not have.

Effects of the Invention As is clear from the above explanation, the present invention applies a phase change to the reproduced low-frequency conversion carrier color signal, which is opposite to the phase change in units of fields and lines received on the recording side. , because it passes through a comb-shaped filter, it is possible to realize an inexpensive phase shift in the reproduction side color signal processing system and a comb-shaped filter in the low-pass conversion carrier color signal band. It is possible to make it into a semiconductor using COD or the like, and it is also easy to convert it into a digital signal and process it. Therefore, the signal processing system on the playback side can be implemented as a single-chip LSI, and extremely useful effects such as cost reduction and reduction in occupied space can be obtained by reducing the number of parts and adjustment steps.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a conventional reproduction side color signal processing system in a VTR, FIG. 2 is a schematic block diagram of a reproduction side color signal processing system according to an embodiment of the present invention, and FIGS. 5 is a schematic block diagram of a reproduction side color signal processing system according to another embodiment of the present invention, and FIG. 6 is an explanation of the operation of the phase converter. FIG. 7 is a block diagram showing an example of the configuration of a digital comb filter. 6... Phase converter, 6... Comb filter, 7... Frequency converter, 8... Local oscillator, 9... Bandpass filter, 1
0...AD converter, 11...Phase converter, 12...Digital comb filter, 13...
...9 person converter, 14 ... frequency converter, 15 ... local oscillator, 16 ...
bandpass filter. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Diin Nρ 12a4 . 5---Note (ω → i, -1---AL shi, /2 Figure 4 □Kisaka number Figure 5 Figure 7/7

Claims (6)

[Claims] (1) The reproduced low-frequency conversion carrier color signal is subjected to a phase change that is opposite to the phase change in field and line units received on the recording side, and then passed through a comb filter. Color video signal processing method. (2) A patent claim characterized in that the phase change in units of field and line is shifted by 90 for each line, processed to reverse the direction in the field, and then passed through a Y-shaped comb filter. A color video signal processing method according to scope (1). (3) A color video signal processing method according to claim (1), characterized in that the comb-shaped filter 1 for passing the low-pass conversion carrier color signal includes an analog delay line in the horizontal scanning period. . (4) The reproduced low-pass conversion carrier color signal is converted into a digital fixture, digitally processed to give a phase change that is opposite to the phase change processed for each field and line during recording, and then digitally processed. A color video signal processing method characterized in that the signal is passed through a comb filter. (5) The color video signal processing method according to claim (4), wherein the phase change by digital processing is constructed by delaying and inverting the digital signal. (6) The color video signal processing method according to claim (4), wherein the digital comb filter includes a delay circuit for one horizontal scanning period using a digital memory and an adder. .