JPS5853834B2 - Color video signal recording/reproducing method and device - Google Patents

Description

[Detailed Description of the Invention] When recording a color video signal on a magnetic tape or the like, the first
According to the method shown in the figure, the amount of recording can be greatly increased.

That is, in FIG. 1, a color video signal is supplied to a low-pass filter 12 through a terminal 11 to extract a luminance signal, and this luminance signal is supplied to an FM modulation circuit 13 to extract frequency components occupying the high frequency side of the recordable band. This FM brightness signal is supplied to the adder circuit 14.

Further, the color video signal is supplied from the terminal 11 to the bandpass filter 15, and the carrier color signal Cs (carrier frequency f,)
is taken out, this carrier color signal C8 is supplied to the frequency converter 16, frequency-converted to a carrier color signal Cc occupying the low frequency side of the FM luminance signal, and this carrier color signal Cc is supplied to the adder circuit 14.

Therefore, the adder circuit 14 obtains a frequency multiplexed signal of the FM luminance signal and the carrier color signal Cc.

The multiplexed signal power is then supplied to the rotating magnetic heads 1 and 2 through the silk amplifier 17, and one field of the multiplexed signal (color video signal) is placed on the magnetic tape 3 as one field, as shown in FIG. The magnetic track 4 is recorded as follows.

However, in this case, as shown in FIG. 3, the angles of the working gaps gljg2 of the heads 1.2 are different from each other, that is, the azimuth angles of the heads 1 and 2 are different from each other so that the adjacent magnetic tracks 4A and 4B Then, their azimuth angles are different from each other.

The carrier frequency of the carrier color signal Cc is set to frequency fa during odd field periods, and set to frequency fb during even field periods.

where k is a positive integer fh horizontal scanning frequency It is.

That is, the carrier frequency fa of the carrier color signal cc. fb is changed to a frequency such that the signals Cc are interleaved with each other every one field period.

Therefore, the carrier frequency of the carrier color signal Cc in the track 4A is fa, and the carrier frequency of the carrier color signal Cc in the track 4B is fa.
The carrier frequency of is f, and the carrier color signals Cc in tracks 4A and 4B have a frequency relationship that interleaves them with each other.

Let us now consider the case where such track 4 is reproduced using the heads 1 and 2 with the same relationship as when recording.

Then, the azimuth angles are different between tracks 4A and 4B, and the FM luminance signal is recorded on the high frequency side, so
The FM luminance signal can be reproduced without causing inter-track crosstalk due to azimuth loss.

Also, even if some crosstalk occurs between tracks,
Because it is considered to be an FM brightness signal.

Since the crosstalk component is suppressed by the reproduction system limiter, an FM luminance signal without inter-track crosstalk can be obtained.

Regarding the carrier color signal Cc, since it is recorded on the low frequency side, we cannot expect a reduction in inter-track crosstalk due to azimuth loss, and inter-track crosstalk occurs in the reproduced carrier color signal CC. There is.

However, the adjacent truck 4A. In 4B, the carrier color signals Cc are in a frequency relationship that interleaves each other, so even if inter-track crosstalk occurs in the carrier color signal CC, the crosstalk component is not the same as the original carrier color signal C.
Frequency interleaving is performed for c.

Such a losstalk component can be easily removed by a C-shaped comb filter.

Therefore, inter-track crosstalk does not occur with respect to the carrier color signal Cc.

Since it is possible to reproduce the FM luminance signal and the carrier color signal without inter-track crosstalk in this way, the width of the guard band between the adjacent tracks 4A and 4B can be narrowed, or as shown in FIG. Signals can be recorded without guard bands or in such a way that adjacent tracks 4A and 4B are partially formed, so that the amount of recording can be greatly increased.

However, in such a recording method, the carrier frequency f8 of the carrier color signal Cs must be converted into the frequency fa or fb every field period in the converter 16, so the signal source of the frequency (f8+fa) and the frequency (
f5+fb) signal sources are required, which complicates the configuration, and since there are two signal sources, signal interference between them becomes a problem.

In view of these points, the present invention increases the recording density by interleaving the carrier frequency of the carrier color signal CC between the tracks 4A and 4B as described above, and at the same time increases the recording density by interleaving the carrier frequency of the carrier color signal CC between the tracks 4A and 4B. , which attempts to prevent signal interference from occurring.

Now, if we consider the case where a signal of frequency fx is balanced modulated by a signal of frequency fy (f, ≦2fx), the modulated signal consists of signal components of frequencies (fx+f,) and (fx-f,), and these The signal component is shifted by f from the original frequency fx.

Therefore, if the carrier color signal Cs is 1/1/1 of the horizontal scanning frequency fh,
If balanced modulation is performed using a signal with a frequency of 2, the modulated signal will deviate from the original carrier color signal Cs by a frequency of 1/2fh, and the modulated signal and the original carrier signal Cs will have an interleaved frequency relationship. Become.

That is, the carrier color signal Cs is converted into a carrier color signal Ca with a carrier frequency fa.
At the same time, this signal Ca is converted to a frequency of 1/2.
If balanced modulation is performed with a signal of fh, the carrier frequency fb (fb-
A carrier color signal cb of fa=Σfh) is obtained.

Therefore, in the present invention, the carrier color signal Ca is set to have a frequency of 1/2.
The carrier color signal fb is modulated by the signal fh, and the modulation is performed by shifting the phase of the carrier color signal Ca every horizontal period.

An example of the present invention will be explained below with reference to FIG.

In FIG. 4, an NTSC color video signal is supplied to a low-pass filter 2 through a terminal 11 to extract a luminance signal, which is supplied to an FM modulation circuit 13 and converted into an FM luminance signal occupying the high frequency side of the recordable band. , this signal is supplied to the adder circuit 14.

Further, the color video signal from the terminal 11 is supplied to a bandpass filter 5 and a C-shaped comb filter 21 to extract a carrier color signal Cs, and this carrier color signal Cs is supplied to a balanced modulation circuit (frequency conversion circuit) 22. At the same time, an oscillation signal of frequency (fs+fa) from the oscillation circuit 23 is also supplied to this, and the carrier color signal Cs is frequency-converted to a carrier color signal Ca of a carrier frequency fa that occupies the lower frequency side of the FM luminance signal. The carrier color signal Ca is supplied to one contact of the switch circuit 24.

At this time, a carrier color signal -Ca having an opposite phase to the carrier color signal Ca is also taken out from the modulation circuit 22 at the same time as the carrier color signal Ca.
This signal -Ca is supplied to the other contact of the switch circuit 24.

Furthermore, the color video signal from terminal 11 is sent to the sync separation circuit 3.
1.32, a horizontal synchronizing pulse and a vertical synchronizing pulse are respectively taken out, and these pulses are respectively supplied to flip-flop circuits 33 and 34, and output from the flip-flop circuit 33 for one horizontal period as shown in FIG. 5A. A pulse Ph that is inverted every field period is taken out, and a pulse Pv that is inverted every field period is taken out from the flip-flop circuit 34 as shown in FIG. 5B.

These pulses Ph and Pv are supplied to the AND circuit 35, and as shown in FIG. A pulse Pk that is inverted to 1 is taken out, and this pulse Pk is supplied to the switch circuit 24 as its control signal.

In this way, the carrier color signal Ca is taken out from the switch circuit 24 during the odd field period Ta, and the carrier color signals Ca and -Ca are taken out alternately every horizontal period during the even field period Tb.

In this case, the line sequential signals of the carrier color signals Ca and -Ca extracted during the even field period Tb have equivalent signal components that are equivalent to the signal obtained by modulating the carrier color signal Ca with a signal of frequency 1/2fh, Further, a signal obtained by modulating the carrier color signal Ca with a signal having a frequency of 172fh has a frequency relationship that ink-leaves with respect to the original carrier color signal Ca.

Therefore, the carrier color signal C obtained during the even field period Tb
The line sequential signal of a and -Ca has a carrier frequency fb (fb=
fa+, fh) carrier color signals.

Therefore, from the switch circuit 24, the odd field period T
A carrier color signal Ca is taken out during the even field period Tb, and a carrier color signal cb is taken out during the even field period Tb.

In this way, the carrier color signals Ca and Cb alternately taken out from the switch circuit 24 every one field period are supplied to the low-pass filter 25 to remove unnecessary components, and then supplied to the adder circuit 14 where they are combined with the FM luminance signal and frequency. The multiplexed signal is sent to the head 1 through the recording amplifier 17.
,2.

The signal in the odd field period Ta is recorded as track 4A, and the signal in the even field period Tb is recorded as track 4B.

The reproduction system is configured as shown in FIG. 6, for example.

That is, a multiplexed signal is reproduced from the track 4 by heads 1 and 2, this multiplexed signal is supplied to a bypass filter 42 through a reproduction amplifier 41, and an FM luminance signal is extracted, and this FM luminance signal is transmitted through a limiter 43 to a demodulation circuit 44. The luminance signal is demodulated and supplied to the adder circuit 45.

Also, the multiplexed signal from the amplifier 41 is filtered through the low-pass filter 5.
1, the carrier color signal Ca is extracted during the odd field period Ta, and the carrier color signal cb is extracted during the even field period Tb.

In this case, due to inter-track crosstalk as described above, the carrier color signal Ca has a crosstalk component of the carrier frequency fb, and the carrier color signal cb has a crosstalk component of the carrier frequency fa.

The field sequential signals of the carrier color signals Ca and cb from the filter 51 are supplied to the balanced modulation circuit 52, and are supplied from the oscillation circuit 53 to the frequency (f5+fa).
) is also supplied.

Therefore, from the modulation circuit 52, the carrier color signal Cs having the original carrier frequency f and the carrier color signal -Cs having the opposite phase are simultaneously taken out during the odd field period Ta, and also during the even field period Tb. is the carrier frequency (f, -1/2f
The carrier color signal Csb of h) and the carrier color signal -Csb having an opposite phase are outputted at the same time.

The signal from this modulation circuit 52 is transmitted to the switch circuit 54.
In addition, circuits 31 to 35 similar to circuits 31 to 35 of the recording system (FIG. 4) are provided, and the luminance signal from the demodulation circuit 44 is supplied to the synchronization separation circuit 31.
, 32, and the pulse Pk shown in FIG.

In this way, in the switch circuit 54, the carrier color signal Cs is taken out during the odd field period Ta, and the carrier color signals Csb and -Csb are taken out alternately every horizontal period during the even field period Tb.

In this case, the line sequential signal of the carrier color signals Csb and -Csb extracted during the even field period Tb is equivalent to a signal obtained by modulating the carrier color signal Csb (carrier frequency f8-T2fh) with a signal of frequency 1/2fh. Therefore, this line-sequential signal has a carrier frequency shifted by the frequency 1/2fh with respect to the carrier color signal Csb, and is a carrier color signal Cs having a carrier frequency fs.

The carrier color signal Cs from the switch circuit 54 is then supplied to a bandpass filter 55 to remove unnecessary signal components (inter-track crosstalk components still remain), and is supplied to a C-shaped comb filter 56. .

In this case, the carrier color signal Ca or c from the filter 51
The carrier frequency of the inter-track crosstalk component included in the signal b is shifted by 1/2fh from the carrier frequency f or fb of the original carrier color signal Ca or Cb, and the crosstalk component is shifted from the carrier frequency f or fb of the original carrier color signal Ca or Cb. Frequency interleaving is performed with respect to Ca or cb.

Therefore, the crosstalk components included in the carrier color signal Cs supplied to the filter 56 are also frequency interleaved with respect to the carrier color signal Cs.

Therefore, when such carrier color signal Cs and crosstalk components are supplied to the filter 56, the crosstalk components are removed and only the carrier color signal C8 is taken out. Therefore, a carrier color signal Cs with no color difference is obtained.

Then, the carrier color signal Cs from the filter 56 is sent to the adder circuit 4.
5 and added to the FM luminance signal to form the original NTS
The signal is output as a C color video signal to the terminal 46.

In this way, according to the present invention, since crosstalk between tracks does not occur, the width of the guard band between the adjacent tracks 4A and 4B can be narrowed, or the guard band can be made so that there is no guard band, or even a part of the guard band overlaps. Signals can be recorded and the amount of recording can therefore be increased significantly.

Also, as in the case of the circuit of FIG. 1, the frequency (f).

Since a signal source of +fa) and a signal source of frequency (f5+fh) are not required, the configuration does not become complicated and signal interference does not occur between these two signal sources.

Moreover, since the conveyance color signal Cs is recorded continuously,
The S/N of the reproduced carrier color signal Cs is good, and a clear color image can be reproduced.

In the above description, the C-shaped comb filter 21°56 is
It can be configured by a delay circuit that delays an input signal by one horizontal period, and a subtraction circuit that subtracts one of the input signal and the delayed signal from the delay circuit.

In addition, the carrier color signals Ca and Cs from the modulation circuit 22.52 are supplied to the filter 25.55 without switching, and the oscillation signal from the oscillation circuit 23.53 is supplied to the filter 25.55 by the pulse Pk every horizontal period in even field periods. The phase may be reversed.

For example, when recording a PAL color video signal,
The frequency of the pulse Ph may be set to 1/4fh.

Further, in the above description, the color video signal is recorded on a magnetic tape, but the present invention can also be applied to a case where a color video signal is recorded on a magnetic medium such as a magnetic sheet or a recording medium such as a film.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of an example of a magnetic recording device, FIG. 2 is a diagram showing the magnetization pattern on the magnetic tape, FIG. 3 is a diagram showing the operating gap of the magnetic head, and FIG. 4 is an example of the present invention. FIG. 5 is a waveform diagram for explaining the system, and FIG. 6 is a system diagram of an example of the reproduction system. 13 is an FM modulation circuit, 22 is a balanced modulation circuit, 21.56
It is a comb filter.

Claims (1)

[Claims] 1. During recording, a color video signal is separated into a luminance signal and a carrier color signal, the separated luminance signal is converted into an angle-modulated signal, and the separated carrier color signal is converted into an adjacent color signal. By controlling the phase relationship of the carrier color signal in a horizontal section separated by an integer horizontal section from the phase relationship of the carrier color signal in a predetermined horizontal section of matching tracks to be inverted, making the carrier color signals have a frequency interleaved relationship with each other, converting the frequency of the angle-modulated signal to a lower frequency side, and adding the frequency-converted carrier color signal and the angle-modulated signal;
This added signal is recorded on the recording medium as the above track,
At the time of reproduction, the angle-modulated signal and the low-pass converted carrier color signal are separated from the added signal reproduced from the recording medium, and the original luminance signal is demodulated from the separated angle-modulated signal. , the separated carrier color signal is reconverted to the original frequency band and phase, and the reconverted carrier color signal is fed to a comb filter to remove crosstalk from adjacent tracks. A method for recording and reproducing color video signals in which the carrier color signal from which talk has been removed is added to the original luminance signal to obtain the original color video signal. 2. A separation circuit that separates a color video signal into a luminance signal and a carrier color signal, an angle modulation circuit that converts the separated luminance signal into an angle modulated signal, and an angle modulation circuit that converts the separated carrier color signal into an angle modulated signal. A converter circuit that converts the frequency of the modulated signal to the lower frequency side, and a horizontal section that is an integer horizontal section apart from the phase relationship of the carrier color signal in a predetermined horizontal section of adjacent tracks in this low-frequency converted carrier color signal. and a circuit that performs control so that the phase relationship of the carrier color signals in the track is inverted, so that the carrier color signals recorded in the adjacent tracks are in a frequency interleaved relationship with each other, and this low frequency conversion and phase Used in the color video signal recording/reproducing power method as set forth in claim 1, wherein a sum signal of the controlled carrier color signal and the angle-modulated signal is recorded on the recording medium as the track. A recording device for color video signals. 3. A separation circuit that separates a color video signal into a luminance signal and a carrier color signal, an angle modulation circuit that converts the separated luminance signal into an angle-modulated signal, and an angle modulation circuit that converts the separated carrier color signal into an angle-modulated signal. A converter circuit that converts the frequency of the modulated signal to the lower frequency side, and a horizontal section that is an integer horizontal section apart from the phase relationship of the carrier color signal in a predetermined horizontal section of adjacent tracks in this low-frequency converted carrier color signal. a circuit for performing the phase relationship of the carrier color signals recorded on the adjacent tracks so that the phase relationship between the carrier color signals is inverted and that the carrier color signals recorded on the adjacent tracks are in a frequency interleaved relationship with each other; a recording head for recording a sum signal of the carrier color signal and the angle-modulated signal on the recording medium as the track; a playback head for reproducing the sum signal from the recording medium; and a sum signal reproduced by the playback head. a separation circuit for separating the angle-modulated signal from the low-pass converted carrier color signal; a demodulation circuit for demodulating the original luminance signal from the separated angle-modulated signal; and a demodulation circuit for demodulating the original luminance signal from the separated angle-modulated signal; a converter circuit that reconverts the color signal to the original frequency band and original phase;
A comb filter removes crosstalk from adjacent tracks from this reconverted carrier color signal, and the carrier color signal from which crosstalk has been removed is added to the original luminance signal to produce the original color image. 1. A color video signal recording/reproducing apparatus comprising an adder circuit for extracting a signal, and used in the color video signal recording/reproducing method set forth in claim 1.