JPS59229984A - Magnetic recording and reproducing system for still picture - Google Patents

Abstract

PURPOSE:To record a still picture with high picture quality by multiplexing two chrominance signals which shift in phase relatively by 180 deg., and recording a carrier luminance signal and the multiplexed chrominance signals on a magnetic medium on frequency multiplex basis. CONSTITUTION:A balanced modulator 12 inputs a color signal B-Y and Acosomegact to generate a balanced modulation signal, which is added to the Asinomegact as a carrier to generate a PM color signal CBt of B-Y. For example, CRt in the obtained PM color signal is inputted to an inverting circuit 16 to control phase inversion with a rectangular wave of 1/2fH, generating a PM color signal + or -CRt which is inverted in phase (by 180 deg.) at every horizontal scanning period (1H). Then, the + or -CRt and CBt are composed and multiplexed to obtain a PM color signal Ct, and a Fm luminance signal CYt obtained by imposing FM modulation upon a luminance signal Y and a reference signal fP of 6fH generated by dividing the voltage of a carrier by, for example, eight through a counter 8 are mixed with the signal Ct on frequency multiplex basis, recording the resulting signal on a magnetic disk 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording/reproducing method for methyl images, and is a method for improving the color signal modulation/demodulation method to improve the image quality of magnetic recording. If you want to use the movie (
(Video) Due to its visual characteristics, it is necessary to record and play back in higher quality than in the case of images. In addition, in the case of magnetic recording of still images, whether it is frame recording or field recording,
Since still images recorded in adjacent recording tracks with different shooting units generally have no picture correlation, it is necessary to record and reproduce them in a manner that prevents crosstalk from occurring from adjacent tracks. Generally, crosstalk is prevented by forming guard bands between recording tracks.

In order to perform high-quality still recording, when modulating the luminance signal (to) and the color signal (C) during recording, it is sufficient to give each a wide occupied band. However, the color signals are R-Y, B-
Since there are two types of reeds such as Y, and these need to be detected independently of each other during reproduction, various problems arise.

Conventionally, there are representative examples (1) to (3) below for recording color signals, but each of them has its own problems. Note that a frequency modulation (FM) method is mainly used for recording luminance signals, and a phase modulation (PM) method is being used in some cases.

(1) A method in which occupied bands that can be separated from each other are assigned to two TV color signals R-Y and B-x, and the signals are FM modulated and recorded.

Since there is an upper limit to the frequency characteristics of magnetic recording, if independent occupied bands are assigned to the luminance signal and two color signals, the occupied band of each signal will inevitably become narrower. Not suitable for

Q) Same < FM modulation, but one occupied band, R
A method of recording by alternately switching -Y and B-Y color signals every horizontal scan. This is called the line sequential recording method.
Although the occupied band of each signal becomes wider, color information 7 is missing for both R-Y and B-Y. The reduction in image quality caused by this lack of color information is not so noticeable during video playback, but
This is noticeable when playing back still images, especially when playing hard copies, so it is not suitable for still recording.

(3) Balanced modulation (BM), which is the key to amplitude modulation (AM)
A method in which two carriers of the same frequency but with a phase shift of 90 degrees are balanced-modulated and recorded separately in R-Y and B-Y. Since the same occupied band is assigned to the two color signals, the occupied band of each signal is wide, and there is no loss of color information, but since it is an AM system, there are some A/D errors such as fluctuations in the touch of the magnetic head during recording and reproduction. If M noise is received, it cannot be removed, so it is essentially unsuitable for still recording.

In view of the above-mentioned problems of the prior art regarding recording of color signals, the present invention provides a magnetic recording system suitable for still recording, which can occupy a wide band for each signal, has no loss of color information, and is not affected by AM noise. The purpose is to provide a playback method.

To achieve the object of the present invention, (a) First, the color signal is recorded by phase modulation, and the first and second subcarriers having the same frequency orthogonal to each other are used as the two color signals. Phase modulates one side at a time. The luminance signal is angularly modulated using either FM or PM.

As a result, even if AM noise is received, the influence of the noise can be removed by passing it through the amplitude limiter. Also, since quadrature two-phase PM modulation is applied to the color signal, two carrier m
(PM) Color signals must occupy the same band, Y
and the occupied band of each of the two C signals becomes wider. Of course, there is no lack of color information.

(b) However, if two PM color signals are simply multiplexed and recorded, residual components will appear in the demodulated signal during reproduction.

Therefore, as a second method, at least one of the two PM color signals, the first sub-carrier and the second sub-carrier is inverted or phase-shifted every horizontal scanning period, and the two P
Processing is performed so that the M color signal is relatively phase-shifted by 180 degrees every horizontal scanning period.

If such processing is performed, at the time of playback, the multiplexed PM color signal is delayed by one horizontal scanning time and is first separated into two PM color signals by adding and subtracting the signals before and after the delay. Then, by demodulating each PM color signal with a phase reference signal whose phase is the same as the phase shift during each recording, complete demodulation without residual components can be achieved.

(c) When PM modulating the subcarrier with a color signal, use balanced modulation (BM) and add another carrier whose phase is delayed by 90 degrees with respect to the carrier to be balanced modulated to the BM output signal of the color signal. PM modulation can be performed by injection. If a PM modulation method using this balanced modulation is adopted, a quadrature two-phase FIM modulation circuit can be realized with a simple configuration. In addition, the demodulation circuit can be easily realized using a balanced modulator and has a good S-matching. However, it goes without saying that any PM demodulation method may be used, and of course any PM modulation method may also be used during recording.

Hereinafter, the present invention will be explained in detail based on the drawings. In addition,
In the embodiment, a magnetic disk is used as the magnetic medium, but the same applies to a magnetic tape or magnetic sheet. Here, to briefly explain the drawings, Fig. 1 is a block diagram showing one embodiment of the recording system, Fig. 2 is a graph showing changes in the value of ~Bessel function, and Fig. 3 is a graph showing crosstalk. An explanatory diagram showing an example of a recording/playback method that prevents this from occurring, Fig. 4 is a block diagram showing an example of a playback system, Fig. 5 is a block diagram showing another example of a playback system, and Fig. 6 is an animation. A simplified block diagram showing an example of a device with a playback function, FIG. 7 is a block diagram showing another embodiment of the recording system, and FIG. 8 is a block diagram showing another embodiment of the playback system corresponding to this. be.

In Figure 1, 1 is a quadrature two-phase PM modulation circuit for color signals, 2 is an FM modulation circuit for luminance signals, 3 is a reference signal creation counter, 4 is a synthesis circuit, 5 is a recording amplifier, and 6 is a magnetic The head, 7 is a magnetic disk, and 8 is a drive motor. The quadrature two-phase FM modulation circuit 1 in this embodiment includes a carrier oscillator 9, a phase shifter 10, two balanced modulators 11.
12, combining circuits 13, 14, and 15, and an inverting circuit 16. The output of the oscillator 9 (if fH is the horizontal scanning frequency, for example, 756 KHz equivalent to 48 fH)
) to three types of carriers A cos by the phase shifter 10
ωct r A sin ω. t, −A sinωc
t is made. One balanced modulator 11 includes, for example, R-Y
A balanced modulation signal is created by inputting the color signal of and -A sinωct, and A cosωct is added as a subcarrier to it to generate the carrier color signal of it -y, that is, the PM color signal CB(t).
make. The other balanced modulator 12 receives color signals B-Y and A.
A balanced modulation signal is created by inputting cosωct, and As1nωct is added as a subcarrier to the B-Y PM.
A color signal CB(t) is generated. Among the PM color signals obtained in this way, for example, CR(t) is inputted to the inverting circuit 16 and 1fH
One horizontal scanning period (IH) by controlling phase inversion with a square wave of
A PM color signal ±CR(t) whose phase is inverted (shifted by 180') is generated every time. ±CR(t) and Cn(t) are synthesized to create a multiplexed PM color signal C(t), and the luminance signal Y is FM modulated on this to produce an FMfJ intensity signal Cy(t).
Then, counter 3 divides the frequency of the carrier by 8, for example, to obtain 6f.
The H reference signal fP is synthesized by frequency multiplexing and recorded on the magnetic disk 7. The recording tracks are formed concentrically.

Generally speaking, in NTSC, for example, a magnetic disk is rotated at 1800 rpm to record 1 track/1 frame, and another is rotated at 3600 rpm and recorded 1 frame.
There are those that perform field recording of one track/one field or frame recording of two tracks/one frame.

Here, the principle of phase modulation using a balanced modulator will be explained.

Now, if the carrier is Acosωct1 modulated signal is f(t) and the constant term is ignored, then the phase modulated PM signal C
(t) becomes the following formula (1).

C(t) = A cos (ωc t + K−f
(t) :] ・=Formula (1) However, if K is a constant and −f(t)<1 at all times t, then the above formula (1)
becomes the following equation (2)・C(t) = A cosωct-A-to-f(t)
sinω. Equation (2) The first term in Equation (2) is a carrier, and the second term represents a balanced modulated wave.

Therefore, it can be seen that in the range -f(t)<1, phase modulation can be performed using a balanced modulator, and sidebands of secondary and higher order can be ignored. Here, K −f (t) <
Considering the conditions for establishing 1, f(t) = a-sinωm1-...Equation (3),
If we substitute this into equation (2) and organize it, we get C(t) =
,A Ccosωct 〒(cos (ω.+ω'm
)t-cos(ω.-0m)t)')...
Formula (4) is obtained. However, -a is added to mp- to represent the maximum modulation index. On the other hand, by substituting equation (3) into equation (1), the first
When expanded in linear terms using the seed Bessel function, -cos (ω.-0m)t)) ...Equation (5) is obtained.Is the range in which Equations (4) and (5) hold -f? It is considered that the range satisfies (t)<:1. Therefore, when considering the value of the Bessel function of the first kind, we get
From Figure 2, mp<1.3 In practice, mp<1.5...
・If Equation (7) is true, Equation (6) holds true as a good approximation.

From the above discussion, it can be seen that phase modulation can be performed by a balanced modulator as long as the modulation index is below the level that the modulation index is satisfied. It can also be seen that phase modulation multiplexing using quadrature two-phase modulation is also possible.

Considering now the upper limit of the modulation index, the upper limit of mp is largely determined visually. Special Public Service 56-51406
When a luminance signal is phase-modulated for the purpose of allowing crosstalk from adjacent trunks, as disclosed in Japanese Patent Application Laid-Open No. 53-41126, mp<1.0 and rmp<Z 1 in practice. , ' 3. but,
Considering that the color signal has a narrower band than the luminance signal, and that still recording is recorded and played back in such a way that crosstalk does not occur, it is considered that an MP of about 1.5 is not a problem in practice. In particular, in the case of phase modulation using a balanced modulator, since there is no secondary sideband, a larger mp f can be tolerated than in normal phase modulation.

Note that as mp increases, the sharpness improves, but distortion increases, but this distortion can be corrected.

Next, the two color signals (R-Y) and (B, -Y) are used as modulation signals, and each has an orthogonal relationship A sinω
. When t and Acosωct are phase modulated using a balanced modulator, the following equations (8) and (9) are obtained. However, (RY).

The voltages of (, B-Y) are ER-Y and EB-Y, respectively.
shall be.

KR, I (B is a constant.

CR(t) = A cosωct −AKR−ER−
Y(t) sinωc1 -...Formula (8) CB(t)
= A sinωat +AKB-En-y(t) c
os ω. t - Equation (9) In order to demodulate ER-Y and EB-Y independently in Equations (8) and Equations (9), (at(t) x sinωat r Cn(t)
It is sufficient to perform synchronous detection like X cosωct. But c(t) = Cn(t) + Cn(t)
...If you simply multiplex it with equation (10),
No matter which phase reference signal, sinωct or cosωct, is used for synchronous detection, the carriers in phase with these are C
(t), a DC component remains and cannot be completely removed.

Therefore, in the present invention, in order to remove the above-mentioned DC component, CR(
CR(t) and CB(t) are interleaved in frequency with each other, that is, using the vertical correlation of the video signal, so that they can be separated by a comb filter during playback.
(t) Either one of the waterfalls can have its phase reversed in one horizontal scanning cycle, or one can advance the phase by 90 degrees every half-water scanning cycle and the other can retard the phase by 90 degrees. Alternatively, CR(t) and CB(t) are multiplexed so that they are phase-shifted by 180 degrees each horizontal scanning period,
become The phase shifting method includes a method of phase shifting the modulator output,
There is a method to phase shift the carrier. For example, as shown in Figure 1, C(t)=±CR(t) 1CB(t)=±[Aco
sω. t-AKR-ER-y(t) sinω. t〕＋
[:As1nωct +AKn e EB-Y(j)
e08ωct]...Equation (11). In the case of demodulation, C(t)
can be separated into CR(t) and CB(t) by delaying the signal by one horizontal scanning time and adding and subtracting the signals before and after the delay. After separation, each can be detected synchronously.

However, since the subtraction process results in ±CR(t), the phase reference signal used for this synchronous detection is also phase-inverted every horizontal scanning period to be ±ginωct. Such a phase shift of the phase reference signal for each horizontal scanning period is, for example, CR(t) by 1.
CB(t) is advanced by 90 degrees in each horizontal scanning period.
This is also necessary when the time is delayed. That is, the phase shift angle of the phase reference signal is determined according to the phase shift angles of CR(t) and Cn(t) during recording. Note that if the phases of the subcarriers are not aligned in each horizontal scan, the separation described above will be incomplete, so the frequency ω of the subcarriers is associated with the horizontal scanning frequency fH.

In magnetic recording of still images, if there is no phase between the images, crosstalk with other images on adjacent recording tracks must not occur. Therefore, generally, a guard band 2n is formed between the recording tracks tn and tn+1 as shown in FIG. 3(a). However, the scanning width jH of the reproducing magnetic head 17
p It is the same as the recording track width rt. but,
In the case of the guard band shown in Fig. 3(a), crosstalk is less likely to occur, but JHP = I! t, therefore, if the reproducing head 17 deviates even slightly from the recording track tn, the reproducing output will decrease and the quality will deteriorate. Therefore, a tracking servo with high precision is required, but the magnetic disk 7
There was an eccentricity in the loading of the playback head 17 during one rotation.
If the recording track tn randomly deviates from the recording track tn, there will be random fluctuations in the playback direction, and the random fluctuations caused by this cannot be compensated for. To solve this problem, as shown in FIG. 3(b) or FIG. 3(c), the scanning width I! of the recording head 6 must be adjusted. I(R and scanning width lHP of the reproducing head 17
The relationship with I! O〉I! , ...Formula (1
2) is sufficient. For example, when considering a plastic film-based magnetic disk of about 40 rtttaφ, the worst case is ±20 μm, taking into account thermal expansion and contraction, humidity expansion and contraction, eccentricity, etc.
The width of the recording track is 7t.
If 80ttm (IHB = 89 μm) and the scanning width IHP of the reproducing head 17 is 40 μm, a constant reproduction output can always be obtained by simple tracking. A reproducing head width of 40 μm is sufficient for current technology. Incidentally, as long as the above formula (12) is satisfied, either a guard band may be formed as shown in FIG. 3(b), or there may be no guard band as shown in FIG. 3(c).

FIG. 4 shows an embodiment of the reproducing system for the first recording, in which 17 is a reproducing magnetic head, 18 is a reproducing amplifier,
19 to 21 are a bypass filter for separating the t'tt FM luminance signal, an amplitude limiter, an FM demodulator,
22 is a demodulation circuit for multiplexed PM color signals. The demodulation circuit 22 of this embodiment includes a band pass filter (BPF) for extracting PM color signals 23.1 horizontal scanning time delay line 2
4, subtracter 25, adder 26, amplitude 1, 1 mitter 27
゜28, flat ain device 29, 30. Low pass filter 3
1.32 and a phase reference signal generator 33. Also,
The phase reference signal generator 33 in this example includes a 48 fH oscillator 34, a phase shifter 35, and an inversion circuit 36. Further, the oscillator 34 in this example includes a 6fH reference signal extraction bandpass filter (BPF) 34a, an amplitude limiter 34b, a counter 34d for frequency division of the voltage controlled oscillator 34, and a phase comparator 34e.

In FIG. 4, the FM luminance signal Cy (t) of the reproduced signal 17a is the same as the conventional <FM demodulated/multiplexed PM color signal (±CR(t) 10B (t))
is extracted by the bandpass filter 23, and the delay line 2
4, separated into ±Cm(t) and CB(t) by subtracter 25 and adder 26, and then amplitude limiter 27.28
through each balanced modulator (BM) 29 .

30. Each balanced modulator 2.9. ．． The phase reference signal given to 30 is ±sinω. t and CO8ωct, which are created as follows. The output 48fH of the voltage controlled oscillator 34c is divided by 8 by the counter 34d, and this is combined with the bandpass filter 34a and the amplitude IJ transmitter 3.
The phase comparator 34c compares the phase of the 6fH reference signal f6 obtained through the oscillation output 4b with the 6fH reference signal f6, thereby controlling the phase of the oscillation output. From this oscillation output, the phase shifter 35 converts sinωct and cosωct.
and cosω. t is -1: It is given to the balanced modulator 30 for BY demodulation. sinω. t is passed through an inverting circuit 36 controlled by a 2fH rectangular wave, and one horizontal scanning period (I
H), it is converted to ±sinωct and then applied to the balanced modulator 29 for R-Y demodulation. The output rear and high-order components of each balanced modulator 29.30 are removed, and ER-Y(t) and EB-Y(
t) are obtained.

Here, the phase reference signal will be described. The phase reference signal required for synchronous detection needs to absorb time axis fluctuations caused by fluctuations in the relative movement between the magnetic disk and the magnetic head both during recording and during reproduction. Therefore, the first
In the embodiment shown in Fig. 4, a 6fH reference signal fp is recorded together with an FM luminance signal and a PM color signal by frequency multiplexing, and during demodulation, this 6fH reproduced signal fQ is used to change the phase of the phase reference signal over time. Adjusts to axis fluctuation. The above reference signal is set below the PM chrominance signal band, such as 6fH, but it may also be between the PM chrominance signal band and the FM luminance signal band. When set to twice the frequency, jitter, phase delay,
When the number of circuits is taken into consideration, the total number and circuit configuration of the phase reference signal generator becomes simple. Another method for obtaining the phase reference signal is to prepare an auxiliary track on the magnetic disk and record either one of the subcarriers there, or to record the first and second subcarriers during the horizontal blanking period. There is a method of using a composite signal of 1, or a method of controlling the phase by detecting rotational fluctuations of the disk drive motor using a frequency generator (FG). In the method using an auxiliary track or FG, the phase of the auxiliary carrier is controlled even during recording.

FIG. 5 shows a reproduction system using a phase reference signal generator based on a method of utilizing subcarriers during the horizontal blanking period. However, the counter 3 shown in FIG. 1 is not required in the recording system. In addition, in FIG. 5, the same parts as in FIG. 4 are designated by the same reference numerals to avoid redundant explanation.

In FIG. 5, the gate pulse circuit 37 manually outputs a pulse 37a having the width of the horizontal blanking period by inputting the horizontal synchronizing signal 38, and the reference signal gate circuit 39 outputs a pulse 37a'f having the width of the horizontal blanking period.
: Open only while receiving a burst reference signal (48
fH, ) 39 a to APC (automatic phase control) circuit 40
send to.

Since there is no signal component during the horizontal blanking period of the color signal, the phase of the subcarrier is constant, and therefore, the output 39a of the reference signal gate circuit 39 is simply a combination of the first and second subcarriers. In the APC circuit 40, a phase detection circuit 42 compares the phase between the oscillation output 41a of the VCO (voltage controlled oscillator) 41 and the inputted reference signal 39a, and the output 42a controls the VCO 41, thereby generating a shiburst state. Output 41 with the same phase and frequency as the reference signal 39a
a is obtained. This oscillation output 41a is transmitted through a 90 degree phase shifter 43
It becomes a constant phase phase reference (No. 8 cosωct) for the balanced modulator 3o for B-Y demodulation. On the other hand, the flip-flop (F/F) 44 uses the horizontal synchronization signal 38 as a clock, and the phase detection circuit 42 Burst reference signal 39a
It is reset by a signal 4-2b which detects the phase of each input and outputs it. Therefore, the output of the flip-flop 44 switches the switch 45 every horizontal run, and the VCO 41
direct output 41a and 180 degree phase shifter (inverting circuit) 4
By alternately giving the output 46a passed through 6 to the balanced modulator 29 for R-Y demodulation, a phase reference signal of ±sinωct is obtained.In the example shown in FIG. sinω. t and is inverted during recording, the phase of the burst reference signal 39a differs by 90 degrees every horizontal scanning period, similar to the burst signal in the PAL system. Therefore, the phase detection circuit 28 of the A20 circuit , the phase reference signal is set as sinω.t for each horizontal scanning period.
A signal 28b can be obtained for inverting.

An example of a magnetic disk device that makes it possible to play back animation by applying the above-described still image magnetic recording/playback method will be described in Section 6C. In Figure 6, Figures 1 and 3
Since the circuit shown in the figure is used, the same parts are given the same reference numerals and redundant explanation will be omitted. In the example shown in FIG. 6(a), an auxiliary track formed, for example, on the outermost circumference of the magnetic disk 7 is used for animation reproduction. Reference numeral 47 denotes a composite main head for still recording, in which a wide head 6 and a narrow head 17 are integrally formed side by side in a row in the track direction. Reference numeral 48 denotes a composite auxiliary five-head for animation reproduction, which also has a wide head 49 and a narrow head 50 integrally formed in the track direction-column. Further, 51 is an erase signal oscillator, 52 is a control unit, 53 is a head position control device, 54 is a magnetic disk rotation counter, 55 and 56 are recording and reproduction amplifiers, and 57 is a tracking pilot signal. The amplifier to extract, S, -S,
is a mode changeover switch. The main head 47 for methyl recording moves in the radial direction of the magnetic disk and is positioned on a desired track, while the auxiliary head 48 for animation reproduction is fixedly positioned on the auxiliary track.

The apparatus shown in FIG. 6(a) has still recording mode SR,
Three types of mode commands are input to the control unit 52: still image reproduction mode (SP) and animation reproduction mode AP. The operation of each mode will be explained with reference to Table 1. Table 1 shows the contact selection of each switch corresponding to the mode.
Contact C of each switch indicates OFF.

<Head feed switch> Only S2 enters the contact point, other switches Str Ss
r84 is turned OFF. Wide head 6 of main head 47
A tracking pilot signal is extracted from the reproduction output and inputted to the control section 52, and a signal for positioning the main head 47 to a desired track is given to the head position control device 53, so that the main head 47 is positioned.

<Erase> S, enters contact A, S2 enters contact A, others are OFF.
It is said that The output of the oscillator 51 is amplified by the recording amplifier 5, and an extinguishing current is applied to the wide head 6 of the main head 47. Note that if erasing must be performed before recording on each track, this erasing mode can be combined with the still recording mode SR.

Still recording mode SR> SI and 82 enter contact a, and the others are turned off.

The synthesis circuit 15 outputs the FM luminance signal Cy(t) and the PM color signal C.
After the (t) and the base code fp are multiplexed and amplified, one field of the video signal is recorded on a desired track by the wide bed 6 of the main head 47.

<Still playback mode sp> Only S3 is turned on to contact a, and the others are turned off.

The reproduction output of the narrow head 17 of the main head 47 is transmitted to the amplifier 18.
and demodulated in the same manner as in FIG. For this,
The video signal for one field is obtained by flashing green, and a still image is played back. <Animation playback mode AP> When continuously shooting a subject with changes using still recording, it is generally necessary to make a smooth video. difficult to play. Basically, after reproducing the same track multiple times, you can move on to the next track and repeat the same process one after another. However, when the head moves from one track to the next, the reproduced image becomes distorted. Therefore, [1] First, put only S and S into contact a, and put the others into O.
FF, and demodulates the playback output of the narrow head 17 of the main head 47, amplifies this playback output as it is, and records it on the auxiliary track by the wide head 49 of the auxiliary head 48. The counter 54 indicates that the magnetic disk has rotated once.
[2] Immediately put only S into the contact point and move the narrow head 50 of the auxiliary head 48 from the auxiliary track recorded just before.
Play using. This reproduction continues for a predetermined number of times on the magnetic disk, during which time the main head 47 is sent to the next track. When the counter 54 detects a predetermined number of rotations, the operation [1] is repeated for the next track. By repeating the above steps, the reproduced image will not be disturbed at all during the movement of the head, and a desirable animation can be reproduced.

The above explanation for FIG. 6(a) is based on one track/track.
This is about field recording of one field, but the same applies to frame' recording of one track/171/-b. In addition, in the case of frame recording of 2 tracks/1 frame, a composite main head 47 f for still recording is used.
Prepare two pieces, one for the first field and one for the second field.
In addition, two composite auxiliary heads 48 for auxiliary track and animation playback may be prepared, one for the first field and one for the second field, and each head may be electrically switched for use for each field.

FIG. 6(b) shows an example in which the digital memory 58 for one field or one frame is used in place of an auxiliary track. In the example of FIG. 6(a), the converter 5
9 and an elbow transducer 60 are used, but are the same.

In the above explanation, the luminance signal is FM modulated to simplify the circuit. In the case of methyl recording, it is necessary to record and play back without receiving crosstalk from adjacent tracks, and several examples are shown in FIG. However, in the unlikely event that a tracking error occurs and the head straddles two tracks during playback, a significant beat disturbance will occur in FM modulation recording. However, it is assumed that the horizontal and vertical synchronization signals are aligned between adjacent tracks.

In order to prevent the above-mentioned beat failure, it is effective to use the tilted azimuth method that has been employed in the past.

However, when the tilted azimuth method is adopted, there are separation points that increase the cost of the magnetic head. Therefore, if the luminance signal is also PM-modulated, beat disturbances will not occur as often.

As a method for recording luminance signals by PM modulation, it is used for recording and reproducing movie images,
Some of them are disclosed in Japanese Patent Application Laid-Open No. 51406 and Japanese Patent Application Laid-Open No. 53-41126. The summary is as follows.

(1) Synchronize the carrier with the relative movement between the magnetic medium and the magnetic head, (II) PM-modulate the carrier with the luminance signal by suppressing the modulation index mp to 1.3 or less, (iii) PM the carrier with the luminance signal, Recording is performed so that the positions of vertical and horizontal synchronizing signals are aligned between adjacent tracks, and the carrier phases are also aligned between descending tracks.

When PM modulation recording is performed in this way, the amplitude of the carrier component recorded on each track is approximately constant because Gv) mp is small, and since the carrier component is in phase between tracks, it is difficult for the head to straddle adjacent tracks. (v) Furthermore, since the mp is small, the sideband components of secondary and higher order can be ignored; (v) Also, since the positions of the synchronization signals are aligned, for these reasons, the playback head Even if the signal straddles adjacent tracks, the reproduced signal merely represents the composite of the two screens. Therefore, no beat disturbance occurs as in FM modulation recording.

Other embodiments of the present invention based on the above considerations are shown in FIGS. 7 and 8. FIG. 7 shows the recording system, and FIG. 8 shows the reproducing system. However, in these figures, except for the PM modulation recording of the luminance signal, there is basically no major difference from FIGS. 1 and 4, so the same parts are given the same reference numerals to avoid redundant explanation.

The recording system shown in FIG. 7 will be explained. In this example, PM, Q
The central carrier of the signal multiplied by t is approximately 7.8 MHz, and P
The center carrier of the M color signal is (about 1.3 degrees),
The reference signal is set to the same < a (approximately 2-6 MHz). 2.6 MHz is an empty frequency between the PM luminance signal band and the PM color signal band.

In FIG. 7, 61 is a carrier generation circuit; 2.
From a 6 MHz oscillator 62, a 2.6 MHz bandpass filter 63, an amplitude limiter 64, a selector switch 65, a frequency divider 66, a tripler circuit 67, and phase shifters 68 and 69. Become. 70 PM the luminance signal (Y)
A balanced modulator for modulation, 71 is a synthesis circuit.

In operation, when recording on an unrecorded magnetic disk for the first time, the switch 65 is set to contact a, PM modulation is performed using the fixed frequency power of the oscillator 62, and the PM luminance signal Cy
(t) and the multiplexed PM color signal C(t).2.
A 6 MHz reference signal fp is multiplexed onto one track. Next, when recording to another trunk, switch 65 is turned on to contact bK, and the auxiliary head (not shown) and BPF 63 output the reference signal f6 from the already recorded track.
(2.6MHz) and create the required carrier from it. As a result, the phases of the carriers are aligned with each other in all tracks.

FIG. 8 shows the reproduction system. The difference from FIG. 4 is that the PM luminance signal is demodulated by a balanced modulator 72, and the frequency of the reference signal fp of /1 2.6 MHz is divided by 2 to create a phase reference signal for demodulating the PM color signal. , and multiply by 3 again to obtain PM4
This is because it creates a phase reference signal for signal demodulation. In the figure, 73 is a bandpass filter, 74 is an amplitude limiter, 75 is a frequency divider by 2, 76 is a triple multiplier, and 77 is a phase shifter.

Although the above explanation relates to magnetic recording, the present invention can also be applied to various other storage devices or transmission systems. An example of application to a system where both coexist is shown in Figure 9. In FIG. 9, 100 is a storage device, 101 and 102 are transmission lines, 103 is a transmitter, 104 is a receiver, 105 is an angle modulation circuit for luminance signals, and 106 is a quadrature two-phase PM for R-Y and B-Y. Modulation circuit, 107, reference signal generation circuit, 108
109 is a carrier luminance signal demodulation circuit, and 109 is a multiplexed PM.
A color signal PM demodulation circuit 110 is a phase reference signal generation circuit. In addition, 105,106°107.108,10
Each of the circuits 9 and 110 may be any of the various circuits described in connection with the magnetic recording described above. In addition, storage device 1
00 can be targeted at various things, for example: ■ converting the modulated signal 4a output from the synthesis circuit 4 into an electrical/optical converter (including LEDs, etc., as well as lasers); A beam-shaped optical signal is converted into an optical signal by exposing a silver halide photosensitive material to optically record the memory, and a beam-shaped optical signal is also irradiated onto a magneto-optical recording medium to perform magneto-optical recording. Memory to do.

■ Various types of semiconductor memory and capacitive memory that record the output 4a of the synthesis circuit 4 as an electrical quantity without converting it into magnetism or light.

■ Various digital magnetic memories that convert the output 4a of the synthesis circuit 4 into digital signals and record them.

There is. Magneto-optical memory, semiconductor memory, and magnetic memory basically record the output 4a of the synthesis circuit 4 by converting it into a digital signal using the PCM or PNM method, but in the case of other storage devices, it is recorded as an analog signal or digital signal. It can often be recorded as a signal. In such a case, the output 4a of the synthesis circuit 4 may be recorded as analog as it is, or it may be sampled and recorded in PAM format, and then converted into PWM format and recorded. However, the output 100a of each storage device 100 is connected to the synthesis circuit 4.
The output 4a is sampled as PAM, PWM, apart from the case where it is analog recorded as a whole.
If the signal is recorded in O format, or in PNM or PCM format, it must be converted into a baseband signal, that is, a signal in the same format as the output 4a of the synthesis circuit 4, using a detection circuit, converter, etc. There is.

As described above with reference to the embodiments, according to the present invention, still images can be recorded and reproduced with extremely high image quality.

[Brief explanation of drawings]

The figures relate to the present invention; FIG. 1 is a block diagram showing an embodiment of the recording system, FIG. 2 is a graph showing changes in Bessel function values, and FIGS. An explanatory diagram showing an example of a recording/playback method that does not cause the occurrence of the problem, FIG. 4 is a block diagram showing an embodiment of the playback system, FIG. 5 is a block diagram showing another embodiment of the playback system, and FIG. 6(a) , (b) is a simplified block diagram of the second side of the device equipped with an animation playback function, FIG. 7 is a block diagram showing yet another embodiment of the recording system, and FIG. 8 shows an example of the corresponding playback system. Block Diagram FIG. 9 is a block diagram showing another example of application of the present invention. In the drawing, R-Y, B-Y are color signals, Y is luminance signal, ±CR(t), CB(t) is PM color signal, Cy(t
) is the angle-modulated luminance signal, C(t) is the multiplexed PM color signal, A sinω. t, A cosωct is the secondary carrier, ±sinωct, cosω. t is the phase reference signal,
fp, fp is a reference signal, 1 is a PM modulation circuit for color signals, 2 is an FM modulator for brightness signals, 6.17 is a magnetic head, 7 is a magnetic disk, 9.34 is an oscillation circuit, 10.35 is a phase shift 11.12, 29, and 30 are balanced modulators, 16.36 is an inversion circuit, 21 is an FM demodulator, 22 is a PM demodulation circuit, and 24 is a delay line for one horizontal scanning time. Patent applicant Fuji Photo Film Co., Ltd. Patent attorney Shibu Mitsuishi (and 1 other person) Fig. 2 9 Jinkun Sai Umaki mp [rad] Fig. 3 7 (0) togn~tn++ 11\-t n+1 to tn+2

Claims (3)

[Claims] (1) For two color signals of the color video signal, the first and second subcarriers of the same frequency, which are orthogonal to each other, are phase-modulated by one side of the color signal, and these two phase-modulated colors are At least one of the two carrier color signals, the first sub-carrier, and the second sub-carrier is used so that the two carrier color signals relatively shift in phase by 180 degrees every horizontal scanning period during the process up to recording. One is inverted or phase shifted every horizontal scanning period, and this relative 180
While multiplexing two carrier color signals whose phases are shifted by degrees,
A magnetic recording method for methyl images, characterized in that a carrier luminance signal obtained by an arbitrary angle modulation method and the multiplexed carrier color signal are frequency-multiplexed and recorded on a magnetic medium. (2) The phase modulation of the color signal is achieved by injecting and synthesizing another carrier whose phase is delayed by 90 degrees with respect to the carrier balancedly modulated by the color signal into the balanced modulation output of the color signal. The magnetic recording system for methyl images according to claim 1, characterized in that it is a phase modulation system using balanced modulation to obtain modulation. (3) For two color signals among the color video signals of the methyl image, the first and second subcarriers having the same frequency, which are orthogonal to each other, are phase-modulated by one side of the color signal, and these two phase modulations are performed. In the process up to recording, the color signals that have been transferred, that is, the two conveyed color signals, are
The two carrier color signals, the first one, are shifted in phase by 80 degrees.
At least one of the sub-carrier and the second sub-carrier is inverted or phase-shifted every horizontal scanning period, and this relative 1
The color of a methyl image is obtained from a magnetic medium recorded by multiplexing two carrier color signals with a phase shift of 80 degrees and frequency-multiplexing the carrier luminance signal obtained by an arbitrary angle modulation method and the multiplexed carrier color signal. In the method of reproducing video signals, the carrier luminance signal and the multiplexed carrier color signal are extracted from the output of the playback head, and the carrier luminance signal is demodulated using a demodulation method that corresponds to the modulation method used during recording, and then multiplexed. The carried color signal is delayed by one horizontal scanning time and separated into two carried color signals by adding and subtracting the signals before and after the delay.
A methyl image reproduction method characterized in that each separated carrier color signal is demodulated with a phase reference signal whose phase is shifted in the same manner as the phase shift at the time of each recording.