JPS5946479B2 - SECAM color video signal recording device - Google Patents

Description

Detailed Description of the Invention When recording and reproducing an NTSC color video signal in a VTR (magnetic recording and reproducing device), at the time of recording, the luminance signal is converted into an FM signal, and the carrier color signal is converted into the FM luminance signal. The frequency is converted to the lower frequency side, and a frequency multiplexed signal of the carrier color signal subjected to the lower frequency conversion and the FM luminance signal is recorded.

During playback, the original color video signal is obtained through signal processing that is reverse to that during recording. Therefore, it is conceivable to record and reproduce SECAM color video signals in a similar manner.

However, the carrier color signal of the SECAM color video signal is N
TSC Gala: Since the modulation format is different from the carrier color signal of the video signal, such recording/reproduction causes the following inconvenience. That is, the carrier color signal Sc of the SECAM color video signal includes an FM signal Br that is FM-modulated by a red color difference signal, and an FM signal F that is FM-modulated by a blue color difference signal.
The M signal Sb is a signal taken out alternately every horizontal period, and the FM signal taken out in an odd-numbered or even-numbered horizontal period is a determination indicating whether the signal Br or Sb is a signal. A signal is included in each vertical retrace period.

The signals Br and Sb have standards as shown in FIGS. 1 and 2, and the signal Br has the maximum frequency deviation Δfr depending on the red color difference signal and the discrimination signal. Signal S
b is the frequency deviation △ due to the discrimination signal and blue color difference signal.
fb becomes maximum. Furthermore, the frequency shift of the signal Br is in the band fr±△f (band of 4.13 to 4.75 MHτ).
and the band fb±△fb (3.
9 to 4.48 MHz), there is a difference in the band. Therefore, for the sake of simplicity, if we consider the case where the carrier color signal Sc is transmitted without frequency conversion, the lower limit of the band of the transmission path is, for example, the lowest value of the frequency deviation of the signal Br, 4.13M.
If it is higher than H2, the carrier wave itself of the signal Br is not transmitted, so that the red color corresponding to the lowest value of 4.13 MHz cannot be reproduced.

Further, it becomes impossible to obtain a discrimination signal for the signal Sb. Similarly, if the upper limit of the band of the transmission path is lower than the maximum frequency deviation of the signal Sb, 4.48 MHz, blue color cannot be reproduced, and a discrimination signal for the signal Sr cannot be obtained.

Therefore, the signal S.

To transmit the signal S. A band of at least 3.9 to 4.75 MHz is required, corresponding to the lowest and highest frequency values. That is, the carrier color signal S. At least 850kHz (=4.75-3.9
MHz) bandwidth is required. Therefore, the carrier color signal S
Even when recording and reproducing O by converting it to a low frequency, a bandwidth of at least 850 kHz is required.

And in fact, signal S. Because it also transmits sidebands, it requires even more bandwidth. However, the carrier color signal S.

If the occupied frequency band is wide, the F located on the high frequency side of this
The frequency band occupied by the M luminance signal becomes higher overall. Therefore, such FM luminance signal and carrier color signal S
In order to record and play back C, the relative speed between the rotating head and the tape must be increased, and to do this, the radius of rotation of the rotating head must be increased and the tape width must be increased. This results in an increase in the size of the VTR and the amount of tape used. Alternatively, instead of increasing the frequency band occupied by the FM brightness signal as a whole, if the frequency shift of the FM brightness signal is reduced to narrow the frequency band occupied by the FM brightness signal, the S/N of the reproduced brightness signal is The quality of the reproduced image deteriorates due to a decrease in the image quality or a decrease in high-frequency characteristics.

Also, the carrier color signal S.

It is also conceivable to convert the FM signal into an AM signal and record and reproduce it in the same way as an NTSC color video signal. However, at the start of each horizontal scan, the phase of the carrier color signal Sc is
Since it is locked to the reference phase or the opposite phase and dot interleaf is performed, the carrier color signal Sc is
When converting an AM signal back to an FM signal, dot interleaf must be performed.

Therefore, the signal system becomes complicated and large due to the conversion of the carrier color signal SOf) from the FM signal to the AM signal, the reconversion from the AM signal to the FM signal, and the dot interleaf. Therefore, the following TR can be considered as a VTR for SECAM color video signals that eliminates the above problems.

First, let me explain about →1.

In FIG. 3, during recording, a SECAM color video signal is supplied to a low-pass filter 12 through an input terminal 11 and a luminance signal is taken out.
It is supplied to the FM modulation circuit 17 through the line of C amplifier 13 -> clamp circuit 14 -> pre-emphasis circuit 15 -> dark and white clip circuit 16, and is made into FM signal Sy. This signal Sy is supplied to adder circuit 19 through high-pass filter 18. Ru.

Further, the color video signal from the terminal 11 is supplied to the pandopass filter 21, and as shown in FIG. 4A, the color video signal S is conveyed.

This signal SO is supplied to an inverse bell filter 22 to have a flat frequency characteristic, and then supplied to a frequency converter 23. Further, the luminance signal from the amplifier 13 is supplied to the synchronization separation circuit 61 through the recording side contact R of the recording/reproduction changeover switch 82 to extract a horizontal synchronization pulse, and this pulse is supplied to the PLLs 62 and 63 to generate a horizontal synchronization pulse. synchronized with the frequency Fmlr, fmb
However, for example, alternating signals of FInr=43fh; 672kHz fn1b=27fh=422kHz are formed, and these signals are sent to the switch circuit 64.
supplied to

Furthermore, the horizontal synchronizing pulse from the separation circuit 61 is supplied to the flip-flop circuit 65 to form a rectangular wave signal Sh that is inverted every horizontal period as shown in FIG. 4B. 64.

Also in this case, the conveyed color signal S from the filter 21. but,
The signal S is supplied to the discrimination circuit 68 through the recording side contact R of the recording/reproduction changeover switch 85. The carrier color signal S is obtained from the discrimination signal included in the carrier color signal S. A signal indicating whether the signal is the signal Sr or the signal Sb is formed, and this signal is supplied to the flip-flop circuit 65 to regulate the phase of the signal Sh. In this way, from the switch circuit 64,
As shown in , the carrier color signal S.

In the horizontal period Tr when becomes the FM signal Sr, the frequency Fmr
Therefore, signal S. An alternating signal SIIl having a frequency FT]11b is extracted during a horizontal period Tb in which the FM signal Sb becomes the FM signal Sb. This signal Sm is then supplied to the frequency converter 66, and is also supplied with the frequency F from the oscillation circuit 67.
However, for example, an oscillation signal of 11f0 = (284--)Fh--Fh; 4.43MHz is supplied to the converter 66, and the converter 6
6, as shown in FIG. 4D, the frequency becomes (FO+Flr) during the period Tr, and the frequency (FO+Flr) during the period Tb.
Fmb) is taken out, and this signal S
n is supplied to the converter 23.

In this way, in the converter 23, the carrier color signal Sc is frequency-converted into the signal Ss by the signal Sn, that is, as shown in FIG. 4E and FIG.
r is the carrier frequency Fsr=FO+Fmr-Fr,
The signal Sb during the period Tb has a carrier frequency Fsb=FO+Fm
b-Fb.

In this case, as is clear from FIG. 5, in the signal Ss, even when the frequency deviation △Fb of the signal Sb becomes maximum, it is within the range of the frequency deviation △Fr of the signal Sr. , Fsr−△Fr. FBb−ΔFb. fBb+△
Fb<Fsr+Fr. Therefore, the occupied frequency band (band including sidebands) of the signal Sb is also within the occupied frequency band of the signal Sr, and the occupied frequency band of the signal S8 is equal to the occupied frequency band of the signal Sr. This signal Ss is then supplied to the adder circuit 19 and added to the FM signal Sy from the filter 18. Therefore, from the adder circuit 19, as shown in FIG. 6, during the period Tr, the FM signal Sy is distributed on the high frequency side, and the carrier frequency F8 is distributed on the low frequency side.
A frequency multiplexed signal St in which a carrier color signal Ss (FM signal Sr) of r is distributed is extracted, and in a period Tb, an FM signal Sy is distributed on the high frequency side and a carrier color signal with a carrier frequency F8b is distributed on the low frequency side. Multiplexed signal S in which S8 (FM signal Sb) is distributed
t is taken out. Then, this signal St passes through the recording amplifier 31 and further through the recording side contact R of the recording/reproducing switch 81 to the two rotating magnetic heads 1A, for example.
, 1B.

The heads 1A and 1B have an angular spacing of 180 degrees from each other, and are rotated by a motor 4 at a frame frequency, and a magnetic tape 2 is wound diagonally over an angular range of more than 1800 degrees with respect to the rotating circumferential surface. At the same time, the tape 2 is run at a constant speed by a capstan and a pinch roller.

Further, the rotation of the heads 1A and 1B is synchronized with the luminance signal by a servo circuit 70. That is, the luminance signal from the amplifier 13 is supplied to the synchronization separation circuit 71 to extract a vertical synchronization pulse, and this pulse is supplied to the frequency division circuit 72 and divided into pulses at the frame frequency. , are supplied to the phase comparator circuit 73 through the recording side contact R of the recording/reproduction changeover switch 83. Also head 1A
, 1B is provided with a pulse generating means 74, for example, on the rotating shaft 5, from which one pulse is taken out for each rotation of the heads 1A, 1B, and this pulse is supplied to the comparator circuit 73 through a shaping amplifier 75. The comparison output of the comparison circuit 73 is supplied to the motor 5 through the amplifier 76, and the rotational phases of the heads 1A and 1B are synchronized with the frame of the luminance signal.

Therefore, the signal St is sequentially recorded on the tape 2 with each field having a guard band as one diagonal magnetic track.

Also, the frequency divided pulse from the frequency dividing circuit 72 is
V, and is further supplied to the magnetic head 78 through the recording side contact R of the recording/reproducing switch 84, and is recorded on the side edge of the tape 2 as a control pulse during reproduction.

The SECAM color video signal is recorded on the tape 2 as described above.

On the other hand, during playback, a control pulse is played back from the tape 2 by the head 78, and this pulse is supplied to the comparator circuit 73 through the line from the playback contact P of the switch 84 to the playback amplifier 79 to the playback contact P of the switch 83. be done.

Therefore, the tracking servo of the heads 1A and 1B for the track is performed, and the heads 1A and 1B scan the track in the same manner as during recording, and receive the multiplexed signal St from the track.
is played. Then, this signal St is applied to the switch 81.
is further supplied to the bandpass filter 42 through the reproduction amplifier 41 to extract the FM signal Sy.
The luminance signal is demodulated by being supplied to a demodulation circuit 44, and this signal is sent to an addition circuit 46 via a de-emphasis circuit 45.
supplied to

Further, the signal St from the amplifier 41 is supplied to the low-pass filter 51 to extract the carrier color signal SB, and this signal Ss is supplied to the frequency converter 52. moreover,
The luminance signal from the de-emphasis circuit 45 is supplied to the synchronization separation circuit 61 through the playback side contact P of the switch 82, and therefore, the luminance signal is supplied from the converter 66 in the same manner as during recording.
As shown in FIG. 4D, an alternating signal Sn is taken out.

This signal Sn is then supplied to the converter 52.
Therefore, in the converter 52, as shown in FIG. 4C, the signals Sr and Sb in the carrier color signal S8 have a carrier frequency F
The signal is frequency-converted to r and fb and becomes the original carrier color signal S8. And this signal S.

is supplied to the adder circuit 46 through the limiter 53 and further through the bell filter 54, where it is added to the luminance signal to form the original SECAM color video signal, which is taken out to the output terminal 47. Recording and reproduction are performed in this way, but in this case, the original carrier color signal SO (Fig. 2)
In the VTR described above, the occupied frequency band of the signal Sr and the occupied frequency band of the signal Sb are different from each other, and therefore the occupied frequency band of the signal Sc is wide.
When the carrier color signal Sc is low-pass converted into the signal Ss, the signal S
Since the signal Sb is located within the frequency band occupied by the signal Sr in 8, the occupied frequency band of the signal S8 may be narrow.

Therefore, in the signal St shown in FIG. 6, the occupied frequency band of the FM signal Sy can be lowered, and therefore
Since the relative speed between the heads 1A and 1B and the tape 2 can be slowed down, the radius of rotation of the heads 1A and 1B can be made smaller, the sub-section of the tape 2 can be made narrower, and the VTR can be made smaller.

Furthermore, since there is no need to reduce the frequency shift in the FM signal Sy, there is no reduction in the S/N ratio of the luminance signal or in high frequency characteristics, and excellent reproduced image quality can be achieved. Also,
The carrier color signal Sc is only subjected to frequency conversion during recording and reproduction, and becomes the carrier color signal S.

Since the phase and frequency information of the dots are not disturbed, dot interleaf can be performed correctly. Moreover, no special circuit or configuration is required for this purpose. However,
In the above-mentioned TR, it is necessary to provide a guard band between adjacent magnetic tracks to prevent inter-track crosstalk from occurring in the signal St, and therefore, it is not possible to record at such high density. Therefore, in the present invention, , which enables even higher density recording.

Therefore, in the present invention, the carrier frequencies Fsr and fsb of the signals Sr and Sb in the signal Ss are relatively in the same relationship as described above, but in one of the adjacent track portions, the carrier frequencies Fsr and fsb of the signals Sr and Sb are set as shown in FIG. On the other hand, low frequency conversion is performed as shown in FIG. 7B.

Then, the signal St is recorded so that the inclinations of the operating gaps of the heads 1A and 1B are different from each other and the tracks on the tape 2 are in contact with each other. If you do this, F
The M signal Sy can be reproduced without inter-track crosstalk due to azimuth loss, and the carrier color signal Ss causes inter-track crosstalk, but after frequency conversion of the signal Ss to the carrier color signal Sc, the band Any crosstalk signals that may be present in the pass filter can be removed.

Therefore, a guard band between adjacent tracks can be omitted, and each track can be formed close to each other or adjacent to each other, so that even higher density recording can be achieved.

[Brief explanation of the drawing]

FIGS. 1 and 2 are diagrams for explaining SECAM color video signals, and FIGS. 3 to 7 are diagrams for explaining the present invention. 11 to 31 are recording systems, 41 to 54 are reproduction systems, and 70 is a servo circuit.

Claims (1)

[Claims] 1 A SECAM color video signal is recorded on a magnetic tape by sequentially forming adjacent tracks in each field period using two magnetic heads with different operating gap inclinations, and in odd-numbered field periods, the red color signal in the conveyed color signal is recorded on a magnetic tape. The FM signal based on the color difference signal and the FM signal based on the blue color difference signal are frequency-converted into a first frequency band by making the occupied frequency bands of the FM signals almost equal using alternating signals having different frequencies, and in the even field period. The FM signal based on the red color difference signal and the FM signal based on the blue color difference signal in the carrier color signal are made into the first frequency band by using alternating signals having mutually different frequencies so that the occupied frequency bands of the FM signals are made almost equal. A recording device for SECAM color video signals, which converts the frequency into a second different frequency band, and records the frequency-converted carrier color signals on the magnetic tape.