JPS63158992A - Color video signal recorder - Google Patents

Abstract

PURPOSE:To record wide-band color video signals in high density so that an accurate time variation is executed at the time of reproducing by multiplexing a luminance signal converted to a low frequency band and a necessary reference signal respectively with two pairs of illuminance signals that are frequency-converted to low bands in synchronism with the leading and trailing edges of an FM modulation wave, then recording them. CONSTITUTION:The luminance signal separated in a comb-line filter 11 is inverted in synchronism with the leading and the trailing edges of an modulation wave by an FM modulator 14 to which modulation frequency is about double that of the luminance signal, and frequency- converted to a low band by 1/2-frequency dividers 16a, 16b, and goes to two signals. To one of these signals, a chroma signal separated by the filter 11 and frequency-divided to a low band by a balanced modulator 21 is multiplexed by an adder 18a, and a resulting signal is recorded by rotary heads 1A, 1B. To the other of the two signals, a reference signal from a 1/8-frequency divider synchronized with H signal is multiplexed, and recording by heads 2A, 2B that are shifted for a track-pitch length from the heads 1A, 1B. In such a way, a high-band luminance signal is divided into two signals to which frequencies are equal to each other, hence the influence of the variation in time base is reduced, a reference signal is made included in a chroma signal, hence the time correction at the time of reproducing becomes more accurate, and as a result, a high-density recording can be executed with a low frequency conversion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video signal recording device, and particularly to a video signal recording device for recording a wideband color video signal.

[Conventional technology]

In recent years, various high-resolution, wideband television signal standards have been proposed in order to improve the reproduction quality of television signals. For example, in the so-called high-def, where the number of scanning lines is 1125 and the luminance signal band is about 20 MHz,
Initiation television (HD-TV) signal, a so-called extended-de which is compatible with current television signals and has a luminance signal band of approximately 8 MHz.
finition television (ED-TV) signals and the like have been proposed.

Considering the recording and playback of these wideband television signals, current video tape recorders have a recordable and playable band of about 4 MHz, and cannot record and playback the above-mentioned wideband television signals. .

Therefore, various VTRs have been proposed in which conventionally, wideband television signals are made into multi-channels, and each channel is limited to a band of about 4 MHz for recording and reproduction.

[Problem that the invention seeks to solve]

However, when assuming a VTR that performs multi-channel recording as described above, even if the composite video signal is converted to multi-track by a simple method such as band division,
The effects of jitter and the like must be removed extremely accurately, and the circuit configuration of the recycled yarn becomes large-scale. In particular, when dividing a video signal into high-frequency components and low-frequency components, the time constants of the circuits that handle the two components are different, so the time constants of these image frequency components are adjusted during playback to restore the original video signal. It was extremely difficult to restore it. In particular, the carrier color signal cannot be reproduced satisfactorily because small jitters cause hue shifts.

Furthermore, when considering separating a composite video signal into component signals such as R, G, and B components for recording, each component signal is a wideband signal, so each of these must be converted into a multichannel signal. Since the number of channels increases dramatically, high-density recording cannot be performed.

The present invention has been made in view of the above-mentioned problems, and is capable of recording wideband color video signals at high density, and is capable of recording color video signals in a manner that accurately eliminates time axis fluctuations that occur during playback.
An object of the present invention is to provide a video signal recording device.

[Means for solving problems]

For this purpose, the color video signal recording device of the present invention includes a first signal that is inverted in synchronization with the rise of an FM modulated wave obtained by FM modulating a luminance signal in a video signal;
a second signal that is inverted in synchronization with the falling edge of the FM modulated wave, and frequency-converts the chroma signal in the video signal to a lower frequency range of the first signal and the second signal. 1 signal and a second signal, and a reference signal of a predetermined frequency within the band of the low frequency converted chroma signal is multiplexed onto the other of the first signal and the second signal and recorded respectively. It was configured to do this.

[For production]

By configuring as described above, a wideband luminance signal has an extremely simple configuration, can be handled in the same format, can be divided into two signals with equal information frequency, and can reduce the adverse effects of time axis fluctuations. Since the reference signal can be recorded, extremely accurate time axis correction is possible for the chroma signal during playback.

Therefore, the wideband color video signal recorded by the recording apparatus of the present invention can be reproduced satisfactorily without time axis fluctuation.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail.

In the following, it is assumed that the input video signal is an NTSC signal with a luminance signal band of about 8 MHz.

FIG. 1 is a block diagram showing the configuration of a recording system of a VTR as an embodiment of the present invention, and FIGS. 2(A) and 2(B) are diagrams showing head arrangement in the VTR of FIG. 1.

In the VTR of this embodiment, the modulation frequency of the luminance signal is about twice that of the conventional one (for example, the sync chip part is
．． 4MHz, white peak part is 10.8MHz), and forms a signal that inverts in synchronization with the rising edge of this FM modulated wave and a signal that inverts in synchronization with the falling edge of the FM modulated wave,
These are assumed to be two channel luminance signals. Then, a low frequency converted chroma signal is superimposed on one of the luminance signals of these two channels, and a reference signal of the low frequency carrier frequency (r LSC) of this chroma signal is superimposed on the other. Furthermore, the sum signal of the L channel and R channel of the stereo audio signal is superimposed on one channel, and the difference signal is superimposed on the other channel so that their bands are arranged between the luminance signal and the chroma signal. The purpose is to simultaneously record the two channels of recording signals obtained in this way.

In FIG. 2, IA and IB are heads for recording the first channel recording signal, and 2A and 2B are heads for recording the second channel recording signal. Head IA
, IB rotate at 30 revolutions per second with a phase difference of 1806 degrees, and the heads 2A and 2B, which rotate with a phase difference close to these, rotate with a phase difference of 180 degrees. The azimuth angles of each head IA, IB, 2A, and 2B are +1O°, -1O°, +30', respectively.
-30°. As shown in Figure 2 (A), these four
A magnetic tape 4 is wound over an angular range of 180° or more around a rotating cylinder 3 to which two heads are fixedly attached, and the cylinder 3 rotates in the direction shown by an arrow 5. Also head IA
and 2A, heads IB and 2B are fixedly installed on the cylinder 3 so as to have a predetermined step Tw, as shown in FIG. 2(B), and this Tw almost matches the track pitch. FIG. 3 is a diagram showing a recording pattern on a magnetic tape when recording is performed using the head shown in FIG. 2. As shown in the figure, two tracks are formed at the same time,
Track TIA where the first channel signal is recorded
, T IB and the tracks T 2A and 72B on which the second channel signals are recorded are arranged alternately. As for the azimuth angle, as shown in the figure, there is always a difference of 20' or more between adjacent tracks, which serves to prevent crosstalk from adjacent tracks during reproduction. The magnetic tape 4 is rotated at 2 times per 1800 rotations (1/60 seconds) by a capstan or the like (not shown).
The vehicle is made to travel a distance corresponding to Tw.

Hereinafter, the recording signals supplied to each head will be explained in detail based on FIG. 1.

In FIG. 1, 10 is an input terminal for a composite NTSC signal, and the input signal is separated into a luminance signal Y and a carrier color signal (chroma signal) C by a comb filter 11. The brightness signal Y has its high frequency components cut by a low pass filter (LPF) 12, and is then passed through a clamp circuit.

The signal is supplied to a luminance signal processing circuit 13 including well-known circuits such as a clip circuit and a pre-emphasis circuit. The luminance signal processed by the circuit 13 is supplied to the FM modulator 14, and the modulation frequency is twice that of the conventional one (for example, the sync chip part is 8.4MH).
z, white peak part 10.8MHz).

This FM-modulated luminance signal is shaped into a pulse shape by a pulse shaping circuit 15, and then passed through a 172 frequency divider 16a.

16b, respectively. The 1/2 frequency divider 16a performs 1/2 frequency division by inverting the high level (Hi) and low level (Lo) at the rising edge of the pulse output from the pulse shaping circuit 15. At 16b, Hi and LO are inverted at the falling edge to perform 1/2 frequency division. That is,
The 1/2 frequency divider 16a stores the timing of the rising edge of the pulse related to the FM modulated wave, and the 1/2 frequency divider 16b
Similarly, the timing of the falling edge will be preserved. This situation is shown in Figure 4 (a), (b), (
C), shown in (d). Ca') in the figure is FM modulator 1
4, (b) is the output of the pulse shaping circuit 15, (C)
is the output of the 1/2 frequency divider 16a, (d) is the output of the 1/2 frequency divider 1
6b are shown respectively.

The signals frequency-divided as described above (luminance signals of the first channel and the second channel) are each passed through a bypass filter (HPF
) 17a and 17b, and attenuates band components for a low frequency converted chroma signal, a low frequency carrier reference signal, and an FM modulated audio signal, which will be described later, and adders 18a and 18b.
supplied to

On the other hand, the chroma signal separated by the comb filter 1 is band-limited by a bandpass filter (BPF) 19, level-adjusted by a well-known ACC circuit 20, and then supplied to a balanced modulator (BM) 21 that performs frequency conversion. be done. In BM21, the carrier frequency of the chroma signal is converted to a low frequency (47- * f H#74 in this example) by a frequency conversion signal described later.
3KHz). The LPF 24 passes only the low-frequency converted signal during the output of the BM 21, and supplies it to the adder 18a as a low-frequency converted chroma signal. This adder 18a
Now, the luminance signal of the first channel and this low frequency converted chroma signal are added.

The frequency conversion signal will be explained below.

A horizontal synchronizing signal (HD) separation circuit 23 separates the HD signal from the NTSC television signal input to the terminal 10 and uses it as one input of the phase comparator circuit 40 . Phase comparison circuit 40
The output of 1,117) controls a voltage controlled oscillator (VCO) 41 with a center frequency of 378f+-+.
The output is divided by a 1/378 frequency dividing circuit 42, and the frequency is
The signal H is used as the other input signal of the phase comparator 40. V
The output signal of the CO 41 is supplied to a 1/8 frequency divider 43, and this 1/8 frequency divider 43 provides a signal of 47.2 that is phase-synchronized with the HD.
Obtain a 5fH reference signal. This 47.25fH is the low frequency carrier frequency f SCL of the low frequency converted chroma signal, and the output signal of this frequency divider 43 is supplied as a reference signal to the adder 18b and added to the luminance signal of the second channel.

BM45 is the output signal of this 1/8 frequency divider (f SCL
) and the color subcarrier frequency of the NTSC television signal (
The output signal (r sc ) from the crystal oscillator 44 of 3.58 MHz (fsC) is balanced-modulated. In the BPF46, in the output signal of this BM (f sc + f SCL
) components are separated and input to the phase inversion circuit 47 at the next stage.

The phase inversion circuit 47 inverts the input signal every one horizontal period (H) in response to the output signal of the inversion control circuit 48. As a result, the frequency of the frequency conversion signal input to BM21 is l / 2 f with respect to fsc + fsct.
As a result, the carrier frequency of the low-frequency converted chroma signal output from BM21 is also shifted by l with respect to f SCL.
/ 2 f H shift.

As shown in Figure 3 above, the first channel signal and the second
Channel signals are recorded on tracks adjacent to each other, but the carrier frequency of the low-frequency converted chroma signal multiplexed on the first channel luminance signal and the frequency of the reference signal multiplexed on the second channel luminance signal are 1. /2 fH shift, and even if these two signals become crosstalk components with each other during reproduction, they can be removed.

Further, the L channel audio signal input from the input terminal 25 and the R channel audio signal input from the terminal 26 are supplied to an adder 27 and a subtracter 28, respectively. The adder 27 outputs the sum signal of both channels (L+R
), and the subtracter 28 outputs the difference signal (L-R) of both channels.
are obtained, and these are subjected to processing such as emphasis and logarithmic compression in the signal processing zones i29 and 30, and then sent to the FM modulator 31.
．． 32.

The received FM output from this FM modulator 31 and 32
The modulated audio signal is added to the first channel and second channel signals by adders 33a and 33b.

The pilot signal generation circuit 34 is a circuit that generates a pilot signal for tracking control using a well-known four-frequency method, and generates four types of pilot signals by dividing the oscillation signal of the oscillator 35 with four different frequency division ratios. Output sequentially. This frequency division ratio is 30H, which is related to the rotational phase of the head.
It is sequentially switched at the timing based on the rectangular wave signal (PG) of z. Note that this PG is output by the PG generator 36.

The pilot signal obtained in this way is sent to an adder 38a,
38b, and added to the first channel and second channel signals. However, the pilot signal delayed by the delay circuit 37 by the delay in the rotational phase of heads 2A and 2B with respect to heads IA and IB is added to the second channel signal.

The first
．． The frequency allocation of the recording signal of the second channel is shown in FIGS. 5(A) and 5(B). Since this allocation for both channels is exactly the same as that of a conventional VTR, it goes without saying that these are recordable signals. In the figure, Y is a luminance signal, C is a chroma signal, CR is a reference signal, and A is an audio signal.

P indicates a pilot signal component, respectively.

These first. The recording signals of the second channel are supplied to heads IA, IB, 2A, and 2B via recording amplifiers 39a, 39b, 39c, and 39d, respectively, and head IA.

The first channel signal is sent to the head 2A by IB.

2B, the signals of the second channel are respectively recorded on the magnetic tape 4 as shown in FIG. Therefore, four types of pilot signals are sequentially recorded, one type each on two tracks.

FIG. 6 is a diagram showing the configuration of the reproduction system of the VTR of this embodiment. During playback, each head IA and IB.

2A and 2B are tracks TIA and TIB, respectively.
, T 2A , T 2B.

The first channel signals reproduced by heads IA and IB are amplified by head amplifiers 51a and 51b, and each head traces each track by a switch 52a controlled by the PG generated by the PG generator 36 mentioned above. The signal inside is extracted as a continuous signal. The output of this switch 52a is supplied to the HPF 53a, and only the first channel luminance signal included in the reproduced signal is separated. A dropout compensation circuit (DOC) 54a is a circuit that replaces a dropout with a signal from one horizontal scanning period ago when a dropout occurs in the reproduced signal, and the luminance signal of the first channel via the circuit 54a is sent to a limiter. At step 55a, level fluctuations are removed and the signal is shaped into a pulse.

On the other hand, the second channel signal reproduced by the heads 2A and 2B is sent to the head amplifier 51c like the first channel.

The signal is amplified by 51d and made into a continuous signal by switch 52b. Similarly, a pulsed second channel luminance signal is obtained via the HPF 53b, DOC 54b, and limiter 55b. The timing correction circuit 56 corrects the output timing of the luminance signal of the second channel in order to compensate for the relative positional deviation of the head during recording and reproduction.

The first result obtained in this way. The pulsed luminance signal of the second channel is supplied to a synthesis circuit 57 to obtain a pulsed FM modulated luminance signal related to the original broadband luminance signal.

This synthesis circuit 57 is, for example, an exclusive OR circuit (EXOR).
) etc., and the output shown in FIG. 4(e) is obtained.

The FM modulated luminance signal synthesized by the circuit 57 is demodulated by the FM demodulator 58 and returned to the original luminance signal by the signal processing circuit 59 including a de-emphasis circuit and the like.

60 removes frequency components of the chroma signal (frequency components near odd multiples of 1/2 fH) that will be added in a later processing step. After the noise component is suppressed by a noise reduction circuit (NR) 61, the signal is supplied to an adder 62. The ROMA signal separated from the output signal of the switch 52a by the BPF 63a has its reproduction level corrected by the ACC circuit 64a, is then supplied to the 8M 65a, and is returned to the original band using a method as described below. The output of BM 65 a is BP
After being supplied to F66a and having unnecessary frequency components removed, it is supplied to comb filter 68a. This comb filter 68a has a characteristic opposite to that of the comb filter 60 (1/2
(passes components near odd multiples of fH), thereby eliminating leakage of luminance signal components and audio signals, as well as crosstalk components of reference signals of adjacent tracks. The chroma signal thus obtained is sent to an adder 62.
The signal is added to the reproduced luminance signal to obtain a reproduced wideband NTSC signal.

On the other hand, the above-mentioned reference signal separated from the output signal of the switch 52b by the BPFR 3b is made to have a constant reproduction level by the ACC circuit 64b, and then reproduced at 3.58 MHz (by 8M65b).
f sc ) is balancedly modulated by the oscillation output of the crystal oscillator 72. In the output signal of 8M65b, BPF67b has (f
sc + fsct) component is separated and the frequency (f sc + f
set, ) is obtained. This signal is transmitted to the phase inversion circuit 7
1 and output from the inversion control signal 70.
After being inverted every IH by a signal synchronized with D, B M
65a as a frequency conversion signal. Therefore, the frequency of this frequency conversion signal is shifted by 1/2 fH with respect to fsc 10rsct, and from 8M65a, a signal of frequency fsc from which time axis fluctuations have been removed is obtained. The leakage (crosstalk) of the reference signal from the adjacent track becomes a component shifted by 1/2 fH with respect to fSC, and is removed by the comb filter 68a.

Further, the FM modulated audio signal (sum signal) separated from the output of the switch 52a by the BPF 73a is sent to the FM demodulator 7.
After being FM modulated by 4a, the noise reduction circuit 75
At step a, noise removal, etc. according to the aforementioned emphasis and logarithmic compression is performed, and a reproduced sum signal (L+R) is obtained. Similarly, the FM modulated audio signal (difference signal) separated from the output of the switch 52b by the BPF 73b is sent to the FM demodulator 74b.
After being demodulated, a reproduced difference signal (LR) is obtained via the noise reduction circuit 75b. Further, the reproduced difference signal (L-R) is supplied to a timing correction circuit 76 to match the timing with the reproduced sum signal (L+R). These signals are then supplied to an adder 77 and a subtracter 78, from which L channel and R channel reproduced audio signals are obtained, respectively.

In this way, a reproduced wideband NTSC signal is output from the output terminal 100, and the output terminal 101. From 102, reproduced audio signals of L channel and R channel are obtained.

The output signal of the switch 52a is sent to the head I in a delay circuit 79.
The signal is delayed by a period corresponding to the difference in trace timing between A and IB and the heads 2A and 2B, and is added to the output signal of the switch 53a by an adder 80. The output of the adder 80 is supplied to an LPF 81, where the pilot signal component is separated and supplied to a tracking control signal generation circuit (ATF circuit) 82.

Along with this, the ATF circuit 82 performs the well-known processing associated with the four-frequency system using two adjacent tracks that are simultaneously traced as one unit, and obtains a tracking error signal. Based on this tracking error signal, the tracking control circuit 86 controls a capstan (not shown), etc.
The running of the magnetic tape 4 is controlled so that each head accurately traces the target track.

According to the VTR of the above embodiment, it is possible to record a luminance signal having twice the band of the conventional one, and the luminance signals of the first channel and the second channel are FM modulated signals of the same band and do not contain the original information. Since the band is also the same, the influence of time axis fluctuations is small. On the other hand, as for the chroma signal, since the time base fluctuation can be completely removed by the reference signal, a better replayed chroma signal can be obtained although the band width remains the same compared to the conventional method.

Next, another configuration example of a reproduction system of the type that effectively utilizes the reference signal recorded by the apparatus shown in FIG. 1 and completely eliminates time axis fluctuations of the luminance signal will be described.

FIG. 7 is a diagram showing another configuration example of a reproducing system corresponding to the recording system shown in FIG. 1. In the diagram, the same components as in FIG. 6 are given the same numbers, and explanations thereof will be omitted.

In FIG. 7, reference numerals 110 and 111 are variable delay lines, which are connected to the outputs of switches 52a and 52b in order to perform time axis correction of the first channel signal and the second channel signal, respectively.

The reproduction reference signal output from the BPF 63b is input to the 13M 65b via the ACC circuit 64b. BM65b
Then the center frequency is (fsc + fscL) (7)
The frequency of the reproduction reference signal output from the VCO 125 is set to fsc, and the phase is compared with the output signal of the crystal oscillator 120 of 3.58 MHz by the phase comparator 124. Since the output of the phase comparator 124 becomes a signal that continuously shows time axis fluctuations, this signal is used to control the VCO 125 and the variable delay lines (VDL) 110 and 111. This leads to the first. The time axis fluctuations of both second channels can be removed.

112 is an HD separation circuit; 113 is a phase comparison circuit that compares the phase of the HD separated by the HD separation circuit 112 and the output of the 17378 frequency dividing circuit 115; 114 is a phase comparison circuit;
The center frequency controlled by the output of No. 13 is vCO of 378 fH. VCOI 14 (7) Output is 1/37
The signal is supplied to a divide-by-8 circuit 115 to form a well-known AFC circuit. On the other hand, the color burst signal in the chroma signal output from the B-shaped filter 68a is processed by the burst gate circuit (B
G) 119, and its phase is compared with the output of the oscillator 120 described above in a phase comparator 116, and this comparison output also controls the VCO 114. This forms a well-known APC circuit.

The output of CONO vCO114 is 1/8 frequency divider 117i:TE f
scL, and is further balanced modulated by the output of the oscillator 120 in the BM118, and the frequency becomes (f sc + f sc
t ) signal is obtained. This signal is extracted via the BPF 121, inverted every 1H by the phase inversion circuit 122, and input to the B M 65 a. In addition, phase inversion circuit 1
22 is controlled by an inversion control circuit 122.

According to the configuration shown in FIG. 7 as described above, time axis correction can also be performed on the reproduced luminance signal, and the influence of time axis fluctuations on the luminance signal is further reduced compared to the configuration shown in FIG. 6.

Incidentally, in the VTRs of the above embodiments, the FM modulated audio signal and the video signal are frequency multiplexed, but the FM modulated audio signal is recorded in the deep layer of the magnetic edge medium, and the video signal is recorded in the surface layer. By doing so, it is also possible to record on the same track.

Furthermore, although the so-called four-frequency method was used for tracking control, other methods may be used, for example, tracking control may be performed by recording a control signal relating to the track pitch along the edge of the tape and reproducing this control signal. It is also possible.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to obtain a color video signal recording apparatus that can record a wideband video signal and perform recording such that time axis correction can be performed extremely accurately during playback.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a recording thread of a VTR as an embodiment of the present invention, FIGS. 2(A) and (B) are diagrams showing the head arrangement in FIG. Figure 3 is a diagram showing the recording pattern on the magnetic tape by the VTR in Figure 1, Figure 4 is a diagram showing how luminance signals are divided into channels, and Figures 5 (A) and (B) are recordings of each channel. FIG. 6 is a diagram showing an example of the configuration of a VTR playback system corresponding to the recording system shown in FIG. 1. FIG. 7 is a diagram showing a VTR playback system corresponding to the recording system shown in FIG. 1. It is a figure which shows the other example of a structure. IA, IB are rotating heads for the first channel, 2A, 2B
is the rotary head for the second channel, and 14 is the FM for the luminance signal.
Modulator, 15 is a pulse shaping circuit, 16a, 16b are 1/2 frequency dividers, 18a, 18b are adders, 21 is a balanced modulator, 23 is a horizontal synchronizing signal separation circuit, 40 is a phase comparator, 41 is a voltage Controlled oscillator, 42.43 is a frequency divider.

Claims (1)

[Claims] forming a first signal that is inverted in synchronization with the rising edge of an FM modulated wave obtained by FM modulating a luminance signal in a video signal; and a second signal that is inverted in synchronization with the falling edge of the FM modulated wave; A chroma signal in a video signal is frequency-converted to the low frequency range of the first signal and the second signal, and multiplexed on one of the first signal and the second signal, and the low frequency converted chroma signal is 1. A color video signal recording apparatus, characterized in that a reference signal of a predetermined frequency within a band is multiplexed onto the other of the first signal and the second signal and recorded respectively.