JPS5839435B2 - Color video signal recording/playback device - Google Patents

Description

[Detailed Description of the Invention] When recording a luminance signal (black and white video signal) on a magnetic tape or the like, the following method (this allows the amount of recording to be significantly increased and therefore allows for long-time playback) can.

That is, as shown in FIG. 1, the rotating magnetic heads 12 are arranged at 1800 angular intervals from each other and rotated at a rate of 30 times per second, and the magnetic tape 3 is spread along the tape guide drum 4 over an approximately 1800 angular range. Run it diagonally across.

Further, in this case, as shown in FIG. 2, the width direction of the operating gaps g12g2 of the heads 1 and 2, that is, the azimuth angles are different from each other.

Then, the luminance signal is converted into an f'M signal that occupies the high frequency side of the recordable band, and this FM luminance signal is converted to the head 1,
Supply to 2.

Therefore, according to such a recording method, one field of the luminance signal is obliquely recorded on the tape 3 as one magnetic track 5, as shown in FIG.

Therefore, let us consider a case where such a recorded pattern is reproduced using a magnetic head similar to that described above.

Then, the azimuth angle is different between the playback head for track 5A and the playback head for trunk 5B, and the FM luminance signal is recorded on the high frequency side, so there is no inter-track crosstalk due to azimuth loss. Can reproduce FM brightness signals.

Also, even if some crosstalk occurs between tracks,
Since the luminance signal is an FM signal, its crosstalk is suppressed by the limiter action of the limiter in the reproduction system.
Therefore, an FM luminance signal without inter-track crosstalk can be obtained.

In this way, the reproduced FM luminance signal (since no inter-track crosstalk occurs, the width of the guard band between adjacent tracks 5A and 5B can be narrowed during recording, or as shown in Figure 3). , so that there is no guard band, the FM brightness signal can be recorded so that the adjacent tracks 5A and 5B partially overlap, so the amount of recording can be greatly increased, so less tape is used. You can play for a long time.

On the other hand, in order to magnetically record a color video signal, the luminance signal is generally converted into an F'M luminance signal, the carrier color signal is frequency-converted to the lower frequency side of the FM luminance signal, and the frequency-converted carrier The added signal of the color signal and the FM luminance signal is magnetically recorded.

Therefore, when recording the luminance signal using the recording method shown in FIGS. 1 to 3, it is conceivable to frequency-convert the carrier color signal to a low frequency band, add it to the f'M luminance signal, and record the signal simultaneously.

However, if recorded in this way, during playback, the luminance signal will not cause inter-track crosstalk due to the azimuth loss of the playback head, but the carrier chrominance signal has a low frequency band, so the carrier of the adjacent magnetic track will The azimuth loss of the reproducing head is small in contrast to the chrominance signal, and as a result, inter-track crosstalk occurs in the carrier chrominance signal.

The present invention takes these points into account and attempts to prevent inter-track crosstalk from occurring in carrier color signals during reproduction.

Therefore, during recording, the luminance signal is converted to an FM signal so as to occupy the high frequency side of the recordable band, and the carrier color signal is frequency converted to the low frequency side of the f'M luminance signal, and this frequency conversion is performed. In this case, the carrier frequency of the carrier color signal is recorded in every other magnetic track 5A and the remaining every other magnetic track 5B. Select a relationship that will interleave.

That is, as shown in the frequency spectrum of the recording signal in FIG. 4, in every other vertical period Ta (FIG. 4A), F
M luminance signal S and a carrier color signal S with carrier frequency fca.

The multiplexed signal of FM
luminance signal Sy and carrier frequency f.

The carrier color signal S of b. The multiplexed bone is recorded as a magnetic track 5B.

And in this case, shall be.

Figure 6 shows an example of a recording system, teeth, In this example This is the case.

That is, the NTSC color video signal is supplied to the low-pass filter 2 through the terminal 11, and the luminance signal is extracted.
This luminance signal is supplied to the FM modulation circuit 13 to form an FM luminance signal S, and this signal S is supplied to the adder circuit 15 after unnecessary signal components are removed by the bypass filter 4 .

Further, oscillation circuits 16 and 17 are provided, and the oscillation circuit 16 outputs a frequency (f5-7 fh) (for example, f5=3, 58
An oscillation signal with a frequency of
The oscillation signal is taken out, and this oscillation signal is supplied to the other contact of the switch circuit 18.

Furthermore, the color video signal from the terminal 11 is supplied to a vertical synchronization separation circuit 21 to extract a vertical synchronization pulse, and this pulse is supplied to a flip-flop circuit 22, from which one vertical period is divided as shown in FIG. 8A. A pulse Pa is formed which is inverted to the switch circuit 18.
is supplied as its control signal.

Therefore, from the switch circuit 18, as shown in FIG.
fh) signals are taken out alternately in one vertical period.

The oscillation signal from this switch circuit 18 is then supplied to a frequency converter 23.

A variable frequency oscillation circuit 25 is also provided, from which the reference frequency is set to, for example, f.

-4(fca +feb) = 44fh (approximately 693
kHz) is taken out, this oscillation signal is supplied to the down-down circuit 26 and made into a signal of the frequency of the stone, that is, frequency fh. The color video signal is supplied to the horizontal synchronization separation circuit 28, a horizontal synchronization pulse is extracted, and this pulse is supplied to the comparison circuit 27.

Then, in the comparator circuit 27, the signal from the down-down circuit 26 and the horizontal synchronizing pulse from the separation circuit 28 are compared in phase and frequency, and the comparison output is sent to the variable frequency oscillation circuit 25.
is supplied as its control signal.

In this way, the oscillation circuit 25 outputs a frequency f that is locked to a frequency that is 44 times the horizontal frequency fh.

An oscillation signal of =44fh is extracted.

This oscillation signal is then supplied to the converter 23.

Therefore, from the converter 23, as shown in FIG.
f5-i fh) and the frequency (tlG+f,
+-1i-fh) are obtained alternately every vertical period.

The alternating signal from the converter 23 is supplied to the frequency converter 31, and the color video signal from the terminal 11 is supplied to the C-shaped comb filter 32 to provide the carrier color signal S.
(carrier frequency f,) is extracted, and this carrier signal S8
is supplied to the converter 31.

Therefore, from the converter 31, a low frequency converted carrier color signal S is output.

That is, as shown in the seventh diagram, the carrier frequency is f.

a=fo-, fh, (7) Carrier color signal S.

and the carrier frequency is f. b=f o-1-7f h carrier color signal S;

are obtained alternately every vertical period.

The carrier color signal So from the converter 31 is supplied to the adder circuit 15 after unnecessary signal components are removed by a low-pass filter 33 .

In this way, from the adder circuit 15, a multiplexed signal with the frequency spectrum shown in FIG. 4A and a multiplexed signal with the frequency spectrum shown in FIG. 4B are obtained alternately in one vertical period.

The multiplexed signal from the adder circuit 15 is supplied to the head 1.2 through the recording amplifier 34, and one field thereof is recorded as one magnetic track 5 on the tape 3 in the pattern shown in FIG.

In this case, the pulse Pa (FIG. 8A) from the flip-flop circuit 22 is supplied to the servo circuit 35 to perform servo control during recording, and the pulse Pa is supplied to the magnetic head 36, as shown in FIG. Tape 3 as shown
is recorded as a magnetic track 6 on one side of the .

When track 5 recorded in this manner is reproduced using head 1.2, as mentioned above, the FM luminance signal Sy has a high frequency band, so it can be extracted without causing inter-track crosstalk due to azimuth loss. can.

However, since the carrier color signal Sc has a low occupied frequency band,
A reduction in inter-track crosstalk due to azimuth loss such as in the FM luminance signal Sy cannot be expected, and therefore, as shown in FIG. 5A, the carrier frequency f is changed from the track 5A.

During the vertical period Ta during which the carrier color signal Sc of a is being reproduced, the carrier frequency f is transmitted from the adjacent track 5B.

The carrier color signal of track 5B (shown by the dotted line) is simultaneously reproduced as a crosstalk component Sk, and as shown in FIG.

During the vertical period Tb during which the carrier color signal Sc of b is being reproduced, the carrier frequency f is applied from the phosphor track 5A.

The carrier color signal of a (shown by the dotted line) is simultaneously reproduced as the crosstalk component Sk.

However, in this case, the carrier frequency of the carrier color signal Sc in the adjacent magnetic tracks 5A and 5B is f.

a and feb, which are interleaved with each other by f. Therefore, when the carrier color signal Sc is frequency-converted to the carrier color signal Ss of the original carrier frequency f8, the crosstalk component included in the carrier color signal Ss is Sk is interleaved with the signal Ss.

If the crosstalk component Sk is interleaved, the crosstalk component Sk can be removed by supplying the carrier color signal Ss to a C-comb filter.

The present invention performs reproduction in this way.1. Let me explain this below.

In FIG. 7, the head 36 reproduces the track 6 (therefore, the head 36 takes out a differential pulse Pe of the pulse Pa as shown in FIG. 8E, and this pulse Pe is supplied to the servo circuit 4H. Then, tracking servo is performed for heads 1 and 2 on track 5 so that the relationship between heads 1 and 2 and tracks 5A and 5B is the same as during recording.

In this way, from the heads 1 and 2, the multiplexed signal and crosstalk component Sk of the frequency spectrum shown in FIG.
The multiplexed signal and crosstalk component Sk of the frequency spectrum shown in FIG. B are alternately extracted every vertical period.

The signal from this head 1.2 is supplied to a bypass filter 43 through a reproducing amplifier 42, where the f'M luminance signal Sy is extracted from the multiplexed signal, and this FM
The luminance signal Sy is supplied to the demodulation circuit 45 through the limiter 14 and the original luminance signal is extracted, and this luminance signal is supplied to the adder circuit 47 through the amplifier 46.

Further, the signal from the amplifier 42 is supplied to a low-pass filter 52, and a carrier color signal Sc (including the crosstalk component Sk) is extracted.

In this case, as described above, and as shown in FIG. 8F, for example, in the vertical period Ta, the carrier frequency f is set.

a” fc 4 rh carrier color signal Sc and carrier frequency f.

The crosstalk component Sk of b−−fc+〒fh is extracted, and the carrier frequency f is taken out during the vertical period Tb.

b carrier color signal SC and carrier frequency f.

The crosstalk component Sk of a is extracted.

The carrier color signal Sc and crosstalk component Sk from this filter 52 are supplied to the frequency converter 51.

Furthermore, in this playback system as well, the recording system circuits 16 to 28
The same circuits 16-28 are provided.

However, in this case, the oscillation circuits 16 and 17 are variable frequency oscillation circuits, and the synchronization separation circuits 21 and 28 are supplied with a luminance signal from an amplifier 46.

In this way, from the oscillation circuit 16.17, the reference 1 frequency is (fs-7fh), (fs + a fh) as in the recording system.
) are taken out from the switch circuit 18 by the pulse Pa, and these oscillation signals are taken out alternately every vertical period as shown in FIG. 8B.
As shown in FIG. 8C, the converter 23 takes out a signal with a frequency (fo+f8-ifh) during the vertical period Ta, and a signal with a frequency (f) during the vertical period Tb.

+f, +7fh) signals are extracted.

The signal from the converter 23 of the social lever is transferred to the converter 51.
supplied to

Therefore, from the converter 51, as shown in FIG. 8G,
In the vertical period Ta, a carrier color signal Ss with a carrier frequency f, and a crosstalk component S with a carrier frequency (f, -, fh-) are present.
k is obtained, and in the vertical period Tb, a carrier color signal Ss with a carrier frequency f5 and a cross 2 talk component Sk with a carrier frequency (f+-!fh) are obtained.

That is, from the converter 51, the carrier color signal Ss of the original carrier frequency f is continuously obtained, and the crosstalk component Sk of the frequency (f5-7rh) or (f8+Hfh) isotarleaved with respect to this is obtained. is obtained.

The carrier color signal Ss and crosstalk component Sk from this converter 51 are supplied to a C-shaped comb filter 54 through a bandpass filter 53.

In this case, since the carrier frequency (f51 -fh) or (f, +)fh) of the crosstalk component S is interleaved with the carrier frequency f5 of the carrier color signal Sk, this filter 54 (here, The talk component Sk is removed and only the carrier color signal Ss is extracted.

This carrier color signal Ss is then supplied to the addition circuit 41,
Therefore, the original NTSC color video signal can be obtained from the terminal 55σ.

In this case, an oscillation circuit 63 is provided, and when an oscillation signal with an oscillation frequency f8 is supplied to the phase comparator circuit 64, a carrier color signal Ss from the filter 54 is supplied to a burst gate circuit 65 and a burst signal is generated. The signal is taken out, and this burst signal is supplied to a comparator circuit 64, where it is phase-compared with the oscillation signal from the oscillation circuit 63, and the comparison output is sent to the variable frequency oscillation circuit 16, 17 as its control signal.
and thus the carrier color signal S from filter 54
The reference phase of s is stabilized.

However, with only the above configuration, when the phase of the pulse Pa of the reproduction system is reversed and the switching phase of the switch circuit 18 is reversed, the converter 51 outputs the frequency-related carrier color signal Ss and the crosstalk component Sk as described above. You won't be able to get it.

Therefore, in order to prevent this, in the present invention, the phase of the pulse Pa of the reproduction system is further regulated.

Therefore, in the example shown in FIG. 7, the pulse Pe from the head 36 is supplied to the waveform shaping circuit 61, and its shaped output is supplied to the flip-flop circuit 22 as its control signal, and is inverted by the vertical synchronization pulse of the flip-flop circuit 22. The operation is controlled, the pulse Pa is set to a predetermined phase, and the switching phase of the switch circuit 18 is set to the correct state.

Thus, according to the present invention, adjacent tracks 5A and 5B
If the width of the girt band between the
Even if a color video signal is recorded, the color video signal can be reproduced without causing crosstalk between tracks, and therefore can be reproduced for a long time with a small amount of tape used.

Furthermore, since all the carrier color signals Ss are recorded, the S/N of the reproduced carrier color signals Ss is good and a clear color screen can be reproduced.

FIG. 9 shows another example of the recording system, and this example shows the case of the recording system.

That is, a variable frequency oscillation circuit 71 is provided, from which an oscillation signal with a reference frequency of 4 feb is supplied to one contact of the switch circuit 18, and is also supplied to a step-down circuit 72 to generate a frequency of 7 feb. The signal strength 20' is supplied to the multiplier circuit 73 and the frequency 7 fcb"" 4f is increased five times.
ca signal, and this signal is supplied to the other contact of the switch circuit 18.

The switch circuit 18 is switched every vertical period by the pulse Pa, so that a signal with a frequency of 4 fob and a signal with a frequency of 4 foa are alternately taken out from the switch circuit 18 every vertical period.

The signal from this switch circuit 18 is supplied to a down-down circuit 74, where it is down-done to a frequency of 7, and output from the down-down circuit 74 to a frequency f.

b signal and frequency f.

A signal is taken out alternately every vertical period, and is supplied to the converter 23.

Further, this converter 23 is supplied with a frequency f from an oscillation circuit 75.
5 oscillation signals are supplied.

Therefore, a signal with a frequency (f8+fob;) and a signal with a frequency (f, +foa) are alternately taken out from the converter 23 every l vertical period, and this signal is supplied to the converter 31. Carrier frequency f.

b carrier color signal Sc and carrier frequency f.

The carrier color signal Sc of a and the carrier color signal Sc are alternately obtained every vertical period.

Thereafter, recording on the tape 3 is performed in the same manner as in the example shown in FIG.

In this case, the signal from the down-down circuit 72 is transmitted to the down-down circuit 76.
(This signal is supplied as a signal with the frequency fh, that is, the horizontal synchronizing pulse from the separation circuit 28 is supplied to the phase comparison circuit 27 for phase comparison, and the comparison output is used in the variable frequency oscillation circuit. 71 as its control signal, and its oscillation frequency is maintained at 4fob.

FIG. 10 shows a reproducing system corresponding to the recording system of FIG. 9, in which a down-down circuit 74 outputs a frequency f as in the recording system.

b signal and frequency f. The signal a is taken out alternately every vertical period.

Then, the signal from the down-down circuit T4 is supplied to the converter 23, and at the same time, the oscillation signal with the reference frequency f5 is supplied from the variable frequency oscillation circuit 81 to the converter 23, and the converter 23 generates a signal with the frequency (fs+feb).
A signal with a frequency (fs+fca) is taken out every vertical period (alternately), and this signal is supplied to the converter 51.

Therefore, a carrier color signal Ss without a crosstalk component Sk is obtained from the filter 54.

In this example, the burst signal from the burst gate circuit 65 and the oscillation signal from the oscillation circuit 63 are compared in phase in the comparison circuit 64, and the comparison output is sent to the variable frequency oscillation circuit 81 as its control signal. The reference phase of the carrier color signal Ss from the filter 54 is stabilized.

As described above, according to the present invention, color video signals can be reproduced over a long period of time with a small amount of tape used.

Furthermore, the S/N of the reproduced carrier color signal Ss is good, and a clear color image can be reproduced.

In the above description, the C-shaped comb filter 32°54 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.

For example, in the case of a PAL color video signal (in this case, 1 fcb fca a (2k l ) f h may be used).

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 the color video signal is recorded on a recording medium such as a magnetic sheet.

[Brief explanation of drawings]

FIG. 1 is a plan view of an example of a rotating magnetic head device, FIG. 2 is a diagram showing an operating gap of the magnetic head, FIG. 3 is a diagram showing a magnetic track, and FIGS. 4 and 5 explain the present invention. 6 and 9 are system diagrams each showing an example of a recording system, FIGS. 7 and 10 are system diagrams each showing an example of the present invention, and FIG. 8 is a system diagram showing an example of the recording system. FIG. 32 is a C-shaped comb filter, 13 is an FM modulation circuit, and 23.degree. 31 is a frequency converter.

Claims (1)

[Claims] 1 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, and transfers the separated carrier color signal to an adjacent track. A converter circuit performs frequency conversion using the first alternating signal in one of the adjacent tracks, and a converter circuit converts the frequency using the second alternating signal, and the carrier color signal frequency-converted in this converter circuit. is a circuit for generating the first and second alternating signals that are substantially interleaved in frequency with each other in adjacent tracks, and adding the angle-modulated signal and the frequency-converted carrier color signal. a recording medium (a recording head for recording, a reproducing head for reproducing the recorded addition signal, and a separation circuit for separating the angle-modulated signal and the frequency-converted carrier color signal from the reproduced addition signal); and a demodulation circuit that demodulates the original luminance signal from the separated angle-modulated signal.
a discrimination circuit for discriminating between one and the other of the adjacent tracks, and a discrimination output of the discrimination circuit for determining the first and second tracks;
The first and second alternating signals for the corresponding re-frequency conversion
a converter circuit that re-converts the frequency of the separated carrier color signal to the original carrier color signal using the first and second alternating signals for re-frequency conversion; a comb filter that removes crosstalk components from adjacent tracks from the carrier color signal of the comb filter; and an adder circuit that adds the carrier color signal from the comb filter to the demodulated luminance signal; A color video signal recording and reproducing device that obtains the original color video signal from the source.