JPS6313631B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a SECAM color video signal recording system and a recording/reproducing system, in which the phase of a conveying color signal is adjusted approximately 90° every horizontal scanning period only in one of the adjacent tracks. The phase shift of the carrier color signal is recorded by 2 degrees, and during playback, the phase shift of the phase shifted carrier color signal is returned to the original state, and a 2 horizontal scanning period delay circuit is used to remove crosstalk components from adjacent tracks. , the horizontal synchronization sections of the carrier color signals are not aligned in adjacent tracks, and
The purpose of this invention is to provide a system that can record and play back high-quality SECAM system color video signals while maintaining mechanical compatibility even with an azimuth recording and playback system recording and reproducing device that does not have a guard band between adjacent tracks. shall be.

A SECAM color video signal can be used, for example, in a two-head helical scan magnetic recording/reproducing device (VTR).
As a method for recording and reproducing by using the following method, the present applicant previously proposed the following SECAM color video signal recording and reproducing method in Japanese Patent Laid-Open No. 54-37426. In other words, a luminance signal and a frequency-modulated carrier color signal are separated from a SECAM color video signal, the luminance signal is frequency-modulated, and the carrier color signal is transferred to a frequency lower band than the frequency-modulated luminance signal band. For example, the signals are converted by frequency down to 1/4, and both of these signals are mixed and then applied to the magnetic tape by two rotary heads having different azimuth angles, which alternately tilt the magnetic tape in the longitudinal direction. the frequency-modulated luminance signal and the low-frequency conversion carrier chrominance signal are separated from the mixed signal reproduced from the magnetic tape.
The frequency-modulated luminance signal is FM demodulated, and the low-frequency converted carrier color signal is obtained using a frequency multiplier circuit to obtain the carrier color signal in the original band.The two signals are then mixed to produce a reproduced SECAM color video signal. This is the way to obtain it.

According to the method proposed by the present applicant, the reproduced signal obtained by reproducing one track by a rotating head during reproduction also includes crosstalk components from adjacent tracks; Since the frequency-modulated and recorded luminance signal has a high frequency, the azimuth loss is large and is hardly included, whereas the low-frequency conversion carrier chrominance signal has a low frequency, so the azimuth loss is comparatively low. This is a small target and is reproduced as a crosstalk component.

However, in general, the horizontal synchronizing signals are arranged and recorded in a direction perpendicular to the track longitudinal direction (so-called H arrangement), and the low-frequency conversion carrier color signals are recorded with substantially the same modulation signal components. Since the two tracks are recorded adjacent to each other, the crosstalk from adjacent tracks of the low frequency conversion carrier color signal mentioned above has a correlation between the color video signal components at one field interval, and moreover, the modulation signal components are approximately equal to each other. Since the same tracks are recorded next to each other, the frequencies of the reproduced low-frequency conversion carrier signals of the reproduced track and the adjacent track are approximately the same frequency, and the beats of both signals have frequencies close to zero, so they are not crossed. There is almost no influence of talk.

For example, if the tape running speed is reduced without changing the drum diameter, tape width, drum rotation speed, or number of horizontal scanning lines in order to record and play over a longer period of time, as shown in Figure 1, the adjacent track This results in a tape pattern in which the horizontal synchronizing signal recording positions are not aligned. Here, in FIG. 1, 1R, 2B, 3R, ..., 312 are formed sequentially from the right side to the left side.
B, 313R track, 313R, 314B,
..., 624B, 325R track, 1B, 2
R, 3B, ..., 312R, 313B tracks,
313B, 314R, 315B,..., 624R,
Among the 625B tracks, adjacent tracks are 0.75H with different azimuth angle magnetic heads.
The data are recorded with a difference of minutes (H is the horizontal scanning period), and no guard band is provided. In FIG. 1, R and B indicate the recording sections of the carrier color signals (converted to low frequency in this case) in which the color difference signals RY and BY are frequency-modulated, respectively, and the numbers are 1.
It shows the order of horizontal scanning lines in a frame.

However, when playing back a magnetic tape with a tape pattern that is not arranged in H as shown in FIG. Because the carrier frequencies of the color signals are different, the beat frequency due to crosstalk from adjacent tracks extends to high frequencies, and this appears as noise on the reproduced television screen.

The present invention solves the above problems,
One embodiment will be described with reference to the drawings from FIG. 2 onwards.

2 and 3 are block system diagrams of an embodiment of each part of the carrier color signal transmission system according to the present invention, and FIG. 4 is a block diagram of an embodiment of the luminance signal and mixed signal transmission system according to the present invention. A phylogenetic diagram is shown. First, to explain the operation during recording, the SECAM color video signal input to the input terminal 1 shown in Fig. 2 is
The low-pass filter 2 separates the luminance signal, and the bandpass filter 3 separates the carrier color signal of the frequency modulated wave. The luminance signal is outputted from the output terminal 5 after being given a certain amount of delay time by the delay circuit 4.

On the other hand, the carrier color signal taken out from the band filter 3 is composed of the first frequency modulated wave obtained by frequency modulating the color subcarrier frequency _OB with the color difference signal B-Y and the color difference signal R-Y. At color subcarrier frequency
It is a signal that is obtained by frequency-modulating _{the OR} and the second frequency-modulated wave is synthesized alternately in time series every 1H, and has a carrier frequency of 3.9MHz to 4.75MHz, and has a carrier frequency of 3.9MHz to 4.75MHz. is supplied to the FM demodulator 6 of
FM demodulated. The signal extracted as a result of FM demodulation by the FM demodulator 6 is a line-sequential color difference signal in which the color difference signals BY and RY are synthesized alternately in time series every 1H, as shown in FIG. 5A. a,
As you can see from A in the same figure, the line B-Y and the line R-
There is a difference in the achromatic color DC level between the Y line and the Y line. This means that the color subcarrier frequency of the carrier color signal is 4.25MHz (= _OB ) on the color difference signal B-Y line,
4.406MHz (= _OR ) for color difference signal RY line
This is because they are different. Furthermore, since the horizontal synchronization signal part originally does not have a color subcarrier, it is output as noise to the output terminal of the FM demodulator 6.

The line-sequential color difference signal a shown in FIG.
(abbreviated as H circuit) 8 and 9, respectively. The switch circuit 7 is switched and controlled by the output pulse of a monostable multivibrator (hereinafter referred to as monomulti) 10, which will be described later. The SH circuit 8 samples and holds the level of the achromatic portion of the color difference signal transmission line of one of the two color difference signals. In this embodiment, the SH circuit 8 samples and holds the level of the achromatic portion of the transmission line of the color difference signal BY, and supplies its output to the terminal LOW of the switch circuit 7. Therefore, the input signal at terminal RO of the switch circuit 7 is a DC signal at the same DC level as the achromatic portion of the color difference signal BY.

The switching signals and sample-hold pulses supplied to the switch circuit 7 and SH circuits 8 and 9 are generated as follows. That is, the rectangular wave d shown in FIG. 5D (not necessarily a symmetrical rectangular wave) that is phase-synchronized with the horizontal synchronization signal is supplied to the terminal 11 shown in FIG.
The signal is supplied to a flip-flop 12, a sample-and-hold pulse generating circuit 13, and a monomulti 10 shown in the figure. The flip-flop 12 divides the frequency of the above-mentioned rectangular wave d into 1/2, generates a rectangular wave e as shown in FIG. , from its output terminal generates an inverted output of a rectangular wave e as shown in FIG.

The sample-and-hold pulse generation circuit 13 is a circuit that generates two types of sample-and-hold pulses g and h as shown in FIG. 5G and H from the rectangular waves d and e. Here, the achromatic color portion of the transmission line of the color difference signal BY is sampled and held, and at the same time, a second sample and hold pulse h is supplied to S.
The signal is supplied to the H circuit 9, where the achromatic portion of the transmission line of the color difference signal RY is sampled and held.
The output signal of the SH circuit 8 is supplied to terminal RO of the switch circuit 7, and is also supplied to the non-inverting input terminal of the comparator 17, where the level is compared with the output signal of the SH circuit 9, which is supplied to the inverting input terminal. .
The output signal of the comparator 17 is transmitted to the switch circuit 18.
It is supplied to the gate circuit 14 through the terminal A, where it is gated by the rectangular wave e, and then supplied to the reset pulse generation circuit 19, where it is converted into a reset pulse, and further supplied to the flip-flop 12, which resets it. .

Now, the rectangular waves e, sample-and-hold pulses g, h have the relationships shown in FIG. Color difference signal (B-Y)
In such a case, the output of the SH circuit 9
The DC level is the achromatic part of the color difference signal (RY).
Since it is a DC level, it is higher than the output DC level of the SH circuit 8. Therefore, the output of the comparator 17 at this time becomes a low level, and the reset pulse generation circuit 19 is prevented from outputting a reset pulse, so that the flip-flop 12 is not reset.

However, the above rectangular wave e is at a low level of 1H.
When the color difference signal (RY) is output from the FM demodulator 6 during this period, the output of the comparator 17 becomes high level, and a reset pulse is generated from the reset pulse generation circuit 19 to reset the flip-flop 12. . As a result, the relationship is restored such that the color difference signal (BY) is output during the 1H period when the Q output e of the flip-flop 12 is at a low level. As described above, line discrimination for each 1H of the SECAM type carrier color signal is performed.

On the other hand, from the monomulti 10 (actually, this monomulti is connected in two stages in cascade), the signal is kept at low level for a period corresponding to the transmission period of the horizontal synchronization signal portion and the achromatic color portion. A rectangular wave 1 as shown by L is taken out and supplied to the switch circuit 7 as a switching signal, and at the same time, it is also supplied to the gate circuit 20. The switch circuit 7 allows the input color difference signal of the terminal A to pass through and output to the next stage DC shift circuit 21 during the period when the rectangular wave l is at a high level, and outputs the input color difference signal at the terminal B (i.e., the color difference signal B-Y achromatic color level)
is selectively outputted and supplied to the DC shift circuit 21. The DC shift circuit 21 performs a DC shift on the line sequential color difference signal from the switch circuit 7 in response to the pulse m shown in FIG.
Y) and is supplied to the burst pulse addition circuit 22 by canceling the DC level difference between the burst pulse and the burst pulse addition circuit 22.

The burst pulse addition circuit 22 applies the fifth pulse from the burst pulse generation circuit 15 to the line-sequential color difference signal in which the DC level difference from the DC shift circuit 21 has been canceled.
A burst pulse k shown in Figure K is added. As a result, the output signal waveform of the burst pulse adding circuit 22 becomes as shown in FIG. 5B. Furthermore, Figure 5B
In the middle, k ₁ and k ₂ are added burst pulses.
The line-sequential color difference signal b to which the burst pulse has been added is supplied to the clamp circuit 23, where the horizontal synchronizing signal portion is clamped by the clamp pulse i shown in FIG. 5I from the clamp pulse generating circuit 16, and then further balanced. The signal is supplied to the modulator 24, where the carrier wave from the oscillator 25 is subjected to carrier wave suppression amplitude modulation. In this embodiment, the oscillation frequency of the carrier wave of the oscillator 25 is selected to be 4.433619 MHz, which is the same frequency as the color subcarrier frequency of the PAL system.
A line-sequential color difference signal (carrier color signal) c, which has been subjected to carrier suppression amplitude modulation and is taken out from the balanced modulator 24 as shown in FIG. and the third
The circuit shown in the figure performs frequency low-frequency conversion for recording.

The circuit shown in FIG. 3 has the same circuit configuration as the carrier color signal processing system of a known PAL type magnetic recording/reproducing apparatus, except for a part. In FIG. 3, the carrier color signal c is supplied to an amplifier 31, an emitter follower (hereinafter referred to as EF
) 32 and is supplied to a balanced modulator 34 via an ACC circuit 33. On the other hand, 35 is a drum pulse input terminal, and the drum pulse inputted from this terminal is passed through an inverter 37, counted down and phase shifter 38.
The phase shift operation is performed only during the field period in which the drum pulse is at a high level. On the other hand, from the composite synchronization signal in the color video signal to be recorded that has entered the input terminal 36, only the horizontal synchronization signal is separated and outputted by the horizontal synchronization signal separation circuit 39 and applied to the monomulti 40, which then converts it into a reference signal. The signal is supplied to the AFC circuit 41 as a signal.
The AFC circuit 41 is supplied with a PAL horizontal scanning frequency _h signal from the 1/4 frequency divider 46 (rectangular wave d shown in FIG. ) 42 as a control voltage. For example, 160 _h from VCO42
A signal with a frequency of is output and supplied to the countdown and phase shifter 38.

The countdown and phase shifter 38 divides the output signal of the VCO 42 by 1/4 during the high level period of the drum pulse so that the frequency is 40 _h and the phases are mutually equal.
A total of four types of signals differing by 90 degrees are generated and supplied to the gate circuit 43, and during the low level period of the drum pulse, a signal with a constant phase and a frequency of 40 _h is generated and supplied to the gate circuit 43. There is. The gate circuit 43 divides the above-mentioned four types of signals every 1H in accordance with the rectangular wave d of the horizontal scanning frequency _h obtained by sequentially dividing the frequencies of the four types of signals with a 1/10 frequency divider 45 and a 1/4 frequency divider 46. Select and output sequentially. As a result, the gate circuit 43 outputs a phase transition signal with a frequency of 40 _h in which the phase sequentially changes by 90 degrees every 1 h during the high level period of the drum pulse, and is constant during the low level period of the drum pulse. Phase frequency 40 _h
The signal will be extracted. The output signal of this gate circuit 43 is supplied to a balanced modulator 47 via an inverter 44, where it is balanced modulated by a signal of a frequency equal to the color subcarrier frequency of the PAL system from a voltage controlled crystal oscillator (VXO) 52. ,
A bandpass filter 48 extracts only the signal having the frequency that is the sum of both signals. The output signal of this bandpass filter 48 is supplied to the above-mentioned balanced modulator 34,
Here, balanced modulation (frequency conversion) with the carrier color signal is performed.

As a result, the color subcarrier frequency is set to 40 _h from the balanced modulator 34, and the phase is changed every 1 h.
A low-pass conversion carrier color signal (low-pass conversion sub-modulation wave) in which a phase shift period in which the phase shift is sequentially shifted in a fixed direction by 90 degrees and a period in which no phase shift is performed are alternately repeated every field period. taken out,
Furthermore, after unnecessary frequency components are removed by a low-pass filter 49, the signal is outputted to an output terminal 50 via an E.F.

Further, the horizontal synchronization signal taken out from the horizontal synchronization signal separation circuit 39 is applied as a gate pulse to the gate circuit 53, and the rectangular wave shown in FIG. 5F from the output terminal 27 shown in FIG. A 2H period pulse j shown in FIG. J is taken out. This pulse j is generated by the burst gate pulse generation circuit 54.
It is supplied to the burst gate circuit 59, where it passes through a bandpass filter 57 and an E.F 58, respectively. The burst pulse superimposed on the achromatic portion of the transmission line of the color difference signal (BY) is extracted. This burst pulse is supplied to phase comparators 60 and 61, respectively, and phase comparison operations are performed every 2H. Note that the phase comparator 60 applies a constant voltage to the VXO 52 since the oscillator 62 is stopped during recording. Therefore, VXO52 oscillates at a constant frequency of 4.433619MHz. Also at this time, the phase comparator 61
is not used.

The output signal of the burst gate pulse generation circuit 54 is also supplied to the burst gate circuit 55.
The ACC circuit 33 performs burst gate of the color signal input from the switch SW every 2H, and the output thereof is further supplied to the ACC circuit 33 via the detection circuit 56.

The low-frequency converted carrier color signal obtained as described above is supplied from the output terminal 51 to an adder circuit 67 shown in FIG. On the other hand, the luminance signal taken out from the terminal 4 shown in FIGS. 2 and 4 is subjected to appropriate signal processing in the recorded video signal processing circuit 65 shown in FIG. The signal is supplied to an adder circuit 67. Therefore, a composite color video signal obtained by frequency division multiplexing the frequency modulated luminance signal and the low frequency conversion carrier color signal is taken out from the adder circuit 67, and is connected to the recording amplifier 68 and the contact a.
Through two switches 69 and 70 and two rotary transformers 71 and 72, two rotary heads 73 and 74 formed with gaps with different azimuth angles alternately rotate magnetic tape (not shown) upwardly and diagonally for each field. recorded while forming a track. Therefore, in the magnetic tape pattern recorded as described above, the phase of the recorded low frequency conversion carrier color signal for one of the adjacent recording tracks sequentially shifts in a fixed direction by 90 degrees every 1H. It will be done. In addition, the color subcarrier frequency of the low-pass conversion carrier color signal is 1 of the content of the color difference signal.
The frequency is always the same regardless of the change in H.

Next, the operation of the method of the present invention during reproduction will be explained. In FIG. 4, the composite color video signal recorded on the tracks on the magnetic tape is alternately recorded on each track by rotary heads 73 and 74 formed with a gap of the same azimuth angle as the rotary heads that formed the tracks. The preamplifier 7 is regenerated by the switches 69 and 70 connected to contact b during regeneration through the rotary transformers 71 and 72.
5 and 76, and the necessary amplification is performed.
The reproduced and synthesized color video signals taken out from the expansion amplifiers 75 and 76 are alternately synthesized in time series by a changeover switch that is switched every one track reproduction period (one field reproduction period), and then sent to a limiter and a demodulation circuit. 78 and low pass filter 81, respectively.

The limiter and demodulation circuit 78 limits the amplitude of only the frequency modulated luminance signal in the reproduced composite color video signal to remove unnecessary AM components, and then performs FM demodulation to obtain a reproduced luminance signal. This reproduced luminance signal is subjected to necessary signal processing by a reproduced video signal processing circuit 79 and then outputted to an output terminal 80.

On the other hand, the low-pass filter 81 separates only the low-pass converted carrier color signal from the reproduced composite color video signal and sends it to the delay circuit 83 shown in FIG. 3 via the output terminal 82.
and then delayed for a certain period of time. The reproduced low-pass conversion carrier color signal with a color subcarrier frequency of 40 _h taken out from the delay circuit 83 is sent to the amplifier 31 and the E.F3.
2. The signal is supplied to the balanced modulator 34 through the ACC circuit 33, where it is balanced-modulated and returned to the original reproduction carrier color signal. In order to perform the above-mentioned balanced modulation (frequency conversion), this balanced modulator 34 has a frequency equal to the sum of 40 _h and 4.433619 MHz, and a phase of 1 during the high level period of the drum pulse.
The band filter 48 supplies a signal that sequentially moves in a fixed direction by 90° every H and has a fixed phase during the low level period of the drum pulse. VXO5
The burst signal of the reproduced carrier color signal passing through the burst gate 59 and the phase error voltage with the crystal oscillator 62 are supplied to the input to the VXO 52.
control the oscillation frequency. The output of the VXO 52 is sent to a balanced modulator 47 to generate a signal having a frequency equal to the sum of 40 _H , and is supplied to the balanced modulator 34. By doing this, the jitter contained in the reproduced transport color signal is canceled out.

The reproduced carrier color signal taken out from the balanced modulator 34 has a color subcarrier frequency of 4.433619MHz, which is the same as that of the PAL system, and the phase of the high level period of the drum pulse is 1H in the opposite direction to that during recording.
By receiving a phase shift of 90 degrees each time, the phase shift during recording is canceled out, and the phase during the low level period of the drum pulse remains unchanged. This reproduced carrier color signal is passed through a band filter 57,E.
The signal is supplied to the 2H delay circuit 87 through the F58, amplifier 85, and E.F86, respectively. The reproduced carrier color signal extracted after being delayed by 2H from the 2H delay circuit 87 is
The signal is mixed with the reproduced carrier color signal branched out from the amplifier 85 and output to the amplifier 88 .

Here, when reproducing a track in which the low-frequency conversion carrier color signal is recorded after undergoing the above-mentioned phase shift,
Since a phase shift is performed to cancel the phase shift during recording described above, the crosstalk component of the low-frequency converted carrier color signal recorded without phase shift from the adjacent track at this time also has a 90° phase. Since the signal is reproduced according to the transition, the crosstalk components between 2H have opposite polarities. On the other hand, when reproducing a track in which the low frequency conversion carrier color signal is recorded without phase shifting, the track is reproduced without phase shifting, but at this time, crosstalk components from adjacent tracks are The low-frequency conversion carrier color signal component recorded with a phase shift of 90 degrees becomes the crosstalk component as it is.
At this time, the crosstalk components also have opposite polarities in 2H.

On the other hand, the above reproduced carrier color signals are R-Y, B-Y
Since this is a signal obtained by carrier wave suppression amplitude modulation using a line sequential color difference signal obtained by combining two color difference signals alternately in time series every 1H, substantially the same color information is repeatedly obtained every 2H. Therefore, by taking this two-line correlation into account and mixing the input and output of the 2H delay circuit 87 as described above, the crosstalk components from adjacent tracks are canceled out and recorded on the reproduced track. It is possible to extract only the carrier color signal that is present in the image.

In this way, the reproduced carrier color signal (reproduced amplitude modulated wave) from which crosstalk components from adjacent tracks have been canceled out is transmitted to the amplifier 88, the killer amplifier 84, and the level adjuster, which operate by applying a power supply voltage only during reproduction. 89 and then from the output terminal 90 to the second
The signal is supplied to a removal circuit 91 shown in the figure. Note that when the added burst pulse is taken out at a 2H cycle from the burst gate circuit 59 shown in FIG. When the burst pulse is not extracted at all, it is determined that the input signal is a black and white signal, and the operation is controlled so as to cut off its transmission.

In FIG. 2, the removal circuit 91 is an OR
The pulse from the circuit 106 removes the burst pulse in the reproduced carrier color signal from the terminal 90 and the signal portion (a predetermined 9H period after the vertical synchronization signal) into which a line discrimination signal (described later) should be inserted. and supplies it to the demodulation circuit 92. The demodulation circuit 92 is the third
4.433169M extracted from oscillator 62 shown in the figure
A Hz signal is supplied via a terminal 93, and this signal is used to synchronously detect and demodulate the reproduced carrier color signal output from the removal circuit 91 to obtain a line-sequential color difference signal (the waveform of this line-sequential color difference signal is This is a waveform similar to that obtained by removing the burst pulses k ₁ and k ₂ from the signal in Figure 5B).

This line sequential color difference signal is supplied to a DC shift circuit 94, where a pulse n shown in FIG. 5N from the gate circuit 20 gives a level difference between each line DC of the color difference signals RY and BY. This level difference is caused by the carrier frequency of the transmission line of the color difference signal BY at the output end of the FM modulator 97, which will be described later.
4.25MHz, and the DC level difference is such that the carrier frequency of the transmission line of the color difference signal RY is 4.406MHz. The reproduced line sequential color difference signal to which the above DC level difference has been added by the DC shift circuit 94 is supplied to the clamp circuit 95, where the color difference signal B-Y is changed by a 2H cycle clamp pulse from the clamp pulse generation circuit 16. After being clamped at the achromatic portion of the signal, it is supplied to the line discrimination signal addition circuit 96,
Here, the line discrimination signal from the line discrimination signal generation circuit 104 is added to the 9H period after the vertical synchronization signal.

Here, the generation of the above-mentioned line discrimination signal and control pulse will be explained. A rectangular wave d as shown in FIG. be done. Further, a composite synchronization signal q ₁ or q ₂ shown in FIG. 6A or B separated from the reproduced luminance signal enters the input terminal 101, and a vertical synchronization signal r shown in FIG. After being extracted, it is supplied to the line discrimination signal gate pulse generation circuit 103. The line discrimination signal gate pulse generation circuit 103 generates a pulse s shown in FIG. 6D, latches it with a rectangular wave d, and generates gate pulses t ₁ and t ₂ as shown in FIGS. 6E and F, This is connected to the line discrimination signal generation circuit 104 and
The signals are supplied to the OR circuit 106 respectively. Here, the gate pulse t ₁ is generated during the field period when the composite synchronization signal q ₁ is received, and the gate pulse t ₂ is generated during the field period when the composite synchronization signal q ₂ is received.

The line discrimination signal generation circuit 104 uses this gate pulse t ₁ or t ₂ and the rectangular wave (shown in FIG. 5F) which is the output of the flip-flop 17 to generate line discrimination signals u ₁ , as shown in FIGS. 6G and 6H. _u2 is generated and supplied to the line discrimination signal addition circuit 96. The rectangular wave is also supplied to a burst blanking pulse generation circuit 105, which generates a pulse O corresponding to the added burst pulse k as shown in FIG. 5O. This burst blanking pulse o
and gate pulses t ₁ and t ₂ are supplied to the removal circuit 91 via the OR circuit 106.

The line discrimination signal addition circuit 96 outputs line discrimination signals u ₁ and u ₂ having waveforms as shown in FIG. It is added to 9H after the vertical synchronization signal of the output line sequential color difference signal and output to the FM modulator 97. This allows the FM modulator 9
A carrier color signal, which is a frequency modulated wave substantially based on the above-mentioned SECAM method, is extracted from 7 and supplied to an AFC circuit 98 and a low-pass filter 99, respectively. (Since it has a color subcarrier, it is not completely compliant with the SECAM method.)

The AFC circuit 98 demodulates the carrier color signal,
The potential of the achromatic portion of the color difference signal BY is sampled and held using the output pulse of the clamp pulse generating circuit 16 and fed back to the FM modulator 97, thereby stabilizing the oscillation frequency. In addition, the low-pass filter 99 removes unnecessary high-frequency components from the carrier color signal, and then supplies the signal to the planking circuit 100, where the color subcarrier of the horizontal synchronization signal portion is removed by the pulse l from the monomulti 10. It is then used as a reproduced carrier color signal of the SECAM system. This reproduced carrier color signal of the SECAM system is supplied to the mixer 108, where it is taken out from the reproduced video signal processing circuit 79 shown in FIG.
0 and the reproduced luminance signals that have entered through the delay circuit 107 shown in FIG. As a result, the reproduced color video signal of the SECAM system is taken out from the mixer 108 and outputted from the output terminal 109 for monitor reproduction.

Note that during this playback, the input terminal 2 shown in Figure 2
A reproduced carrier color signal to which a burst pulse is added is inputted to 8, and the added burst pulse is detected and extracted by a burst detection circuit 29. A reproduced burst pulse P having a waveform as shown in FIG. During normal operation, when the reproduction burst pulse P is at a high level, the rectangular wave e is at a low level, so the flip-flop 12 is not reset. However, when the rectangular wave e is also at a high level when the reproduction burst pulse P is at a high level, the reproduction burst pulse P passes through the gate circuit 14, passes through the reset pulse generation circuit 19, resets the flip-flop 12, and returns to a normal state. Pull back.

Although the present invention is particularly suitable for application to a magnetic recording/reproducing apparatus having a tape pattern that is not arranged in an H arrangement as shown in FIG. Furthermore, it is applicable not only to magnetic tapes but also to sheet-shaped magnetic disks and other recording media.

As described above, the SECAM color video signal recording method according to the present invention produces a line-sequential color difference signal obtained by frequency demodulating a carrier color signal separated from a SECAM color video signal and synthesizing two color difference signals in time series. Then, the amplitude modulated wave obtained by carrier suppression amplitude modulation with this line-sequential color difference signal is frequency-converted to a low frequency band, and the phase of the low-frequency converted amplitude modulated wave recorded on one of the adjacent recording tracks is changed by one horizontal frequency. Since recording is performed by moving approximately 90 degrees in a predetermined direction every scanning period, even if a track pattern that is not aligned in H is recorded, the carrier frequency of the low frequency conversion amplitude modulated wave can be kept at the same frequency in adjacent tracks. Furthermore, since the burst pulse is superimposed near the achromatic part of one of the color difference signals, the line is set based on this burst pulse during playback. Can perform discrimination and generate line discrimination signals.

Further, the SECAM color video signal recording and reproducing method according to the present invention uses a low frequency conversion amplitude modulated wave reproduced from a recording medium recorded by the recording method according to the present invention as an amplitude modulated wave of the original band, and Only during the reproduction period of the low-frequency conversion amplitude modulated wave recorded with a phase shift, the phase is approximately changed every horizontal scanning period.
The signal is reproduced by moving the amplitude modulated wave by 90 degrees in a direction substantially opposite to that at the time of recording, and demodulates a signal obtained by mixing the reproduced amplitude modulated wave and a signal obtained by delaying the reproduced amplitude modulated wave by a delay circuit for two horizontal scanning periods. to obtain a line-sequential color difference signal, and perform frequency modulation with the line-sequential color difference signal.
Since it is output as a carrier color signal compliant with the SECAM system, even in devices where horizontal synchronization signal recording positions are not lined up in the track width direction between adjacent tracks, low Since the range conversion amplitude modulated wave can be canceled out and removed with the crosstalk component from two horizontal scanning periods ago, the carrier color signal of the SECAM system and
It is possible to reproduce SECAM color video signals with high quality, and also performs line discrimination using burst pulses, and generates line discrimination signals from the reproduced burst pulses, which are used as vertical synchronization signals for line-sequential color difference signals. Since the carrier color signal conforming to the SECAM system is obtained by frequency modulating the signal obtained by superimposing the latter part of the image, it has the advantage of stabilizing the color of the reproduced image.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing the recording positional relationship of the carrier color signal in an example when a SECAM method color video signal is recorded, and FIGS. 2 and 3 respectively show the carrier color signal transmission system in the recording and reproducing method of the present invention. FIG. 4 is a block system diagram showing an embodiment of each part, FIG. 4 is a block system diagram showing an embodiment of the transmission system for luminance signals, etc. in the recording and reproducing system of the present invention, FIGS. 5A to 6A
-H are signal waveform diagrams for explaining the operation of each part in FIGS. 2 and 3, respectively. 1...SECAM color video signal input terminal, 3
...Carrier color signal separation band filter, 5...Luminance signal output terminal, 6...FM demodulator, 7, 18...Switch circuit, 14, 20, 43, 53... Gate circuit, 2
1, 94... DC shift circuit, 22... Burst pulse addition circuit, 24, 34, 47... Balance modulator, 2
6... Amplitude modulated wave (carrier color signal) output terminal, 30...
Amplitude modulated wave (carrier color signal) input terminal, 35... Drum pulse input terminal, 38... Countdown and phase shift circuit, 51... Low frequency conversion amplitude modulated wave (low frequency conversion carrier color signal) output terminal, 81... Reproduction low frequency Converted amplitude modulated wave (reproduced low frequency converted carrier color signal) separation low-pass filter, 87...2H delay circuit, 90... reproduced amplitude modulated wave (reproduced carrier color signal) output terminal, 91... removal circuit, 92... demodulation circuit, 97...FM modulator, 104
...Line discrimination signal generation circuit, 109...Reproduction
SECAM color video signal output terminal.

Claims (1)

[Claims] 1. In a system in which a carrier color signal separated from a SECAM color video signal is frequency-converted to a lower frequency band and recorded on a recording medium, the separated carrier color signal is frequency demodulated to produce two color difference signals. A line-sequential color difference signal is obtained by time-series synthesis of A SECAM characterized in that the phase of the low-frequency conversion amplitude modulated wave recorded on the waveform is recorded by shifting it in a predetermined direction by about 90 degrees every horizontal scanning period.
Color video signal recording method. 2 SECAM system In a method in which a carrier color signal separated from a color video signal is frequency-converted to a lower frequency band and recorded on a recording medium, the separated carrier color signal is frequency demodulated and two color difference signals are synthesized in time series. After generating a line sequential color difference signal, a burst pulse is superimposed near the achromatic color portion of one of the two color difference signals, and the line sequential color difference signal with the burst pulse superimposed has a carrier wave suppression amplitude. The frequency of the amplitude modulated wave obtained by modulation is converted to the above-mentioned low frequency band, and the phase of the low frequency converted amplitude modulated wave recorded on one of the adjacent recording tracks is changed by about 90 degrees every horizontal scanning period. A SECAM color video signal recording method that is characterized by recording transitions in a predetermined direction. 3. The DC level of each achromatic color portion of the line-sequential color difference signal on which the burst pulse is superimposed is substantially the same level.
SECAM color video signal recording method as described in section. 4 The carrier color signal separated from the SECAM color video signal is frequency-converted to a lower frequency band, recorded on a recording medium, and then reproduced as a carrier color signal in the original band.
In the SECAM color video signal recording and reproducing system, the separated carrier color signal is frequency-demodulated into 2
A line-sequential color-difference signal is obtained by time-series synthesis of two color-difference signals, and the amplitude-modulated wave obtained by performing carrier suppression amplitude modulation with the line-sequential color-difference signal is frequency-converted to the above-mentioned low frequency band, and the adjacent recording The phase of the low-frequency conversion amplitude modulation wave recorded on one side of the track is recorded by shifting approximately 90 degrees in a predetermined direction every horizontal scanning period, and during playback, the low-frequency conversion amplitude modulation wave reproduced from the recording medium is recorded. Let the wave be an amplitude modulated wave in the original band, and
Only during the reproduction period of the low-frequency conversion amplitude modulated wave recorded with the phase shift, the phase is shifted by approximately 90 degrees every horizontal scanning period in the direction substantially opposite to that at the time of recording, and the phase is reproduced. A signal obtained by mixing the reproduced amplitude modulated wave and a signal obtained by delaying the reproduced amplitude modulated wave by a two-horizontal scanning period delay circuit is demodulated to obtain the line sequential color difference signal, and the line sequential color difference signal is frequency modulated. A SECAM color video signal recording and reproducing method, which is characterized in that it outputs as a carrier color signal compliant with the SECAM method. 5 The carrier color signal separated from the SECAM color video signal is frequency-converted to a lower frequency band, recorded on a recording medium, and then reproduced as a carrier color signal in the original band.
In the SECAM color video signal recording and reproducing system, the separated carrier color signal is frequency-demodulated into 2
After the two color difference signals are synthesized in time series to form a line sequential color difference signal, a burst pulse is superimposed near the achromatic part of one of the two color difference signals, and the burst pulse is superimposed. The amplitude modulated wave obtained by carrier suppression amplitude modulation using a line-sequential color difference signal is frequency-converted to the above-mentioned low band, and the phase of the low-band converted amplitude modulated wave recorded on one of the adjacent recording tracks is changed to 1. Recording is performed by shifting approximately 90 degrees in a predetermined direction for each horizontal scanning period, and during playback, the low frequency converted amplitude modulated wave reproduced from the recording medium is made into the amplitude modulated wave of the original band, and the phase is shifted. Only during the reproduction period of the low frequency conversion amplitude modulated wave recorded by
The phase is shifted by approximately 90 degrees every horizontal scanning period in the direction substantially opposite to that at the time of recording and reproduced, and the reproduced amplitude modulated wave and the reproduced amplitude modulated wave are
The signals obtained by mixing the signals delayed by the horizontal scanning period delay circuit are demodulated, the burst pulses are removed to obtain the line-sequential color difference signal, and the reproduced burst pulses are used to perform line discrimination and the reproduced A line discrimination signal is generated from the burst pulse, and the line discrimination signal is superimposed on the corresponding part of the line sequential color difference signal after the vertical synchronization signal. Frequency modulation is performed using the line sequential color difference signal obtained, and the transmission is compliant with the SECAM method. SECAM color video signal recording and playback system that is characterized by outputting color signals. 6 Constructing the line-sequential color difference signal obtained by demodulation 2
6. The SECAM color video signal recording and reproducing system according to claim 5, wherein the DC levels of each achromatic color portion of the two color difference signals are made to have a relatively constant difference.