JPS5813093A - Magnetic recording and reproduction method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording and reproducing method that enables high-density recording.

As is well known, in the unified standard ML VTR,
To avoid so-called crosstalk from adjacent tracks that can occur during playback, guard bands can be installed between video tracks. However, in the ninth stage when moving to the small part (1), it is necessary to remove the guard band that does not participate in recording to increase the recording density.

Therefore, we realized a small VTR and adopted the 9 VH8 standard II VT.
R uses rounding, azimuth recording, and color phase shift recording to reduce crosstalk between adjacent tracks.

FIG. 1 is a diagram explaining the principle of the azimuth recording method.

In the figure, W indicates the video track width, 1 indicates the gap of the CH-1 head with respect to the supplementary track width W direction, and b indicates the gap of the CH-2 head with respect to the track width W direction.

If the gap inclination angles of the heads of CH-1 and CH-2 are each 0/2, the gap angle between the two heads is:
As shown in the figure, it becomes -.

In such a situation, if what was recorded on the CH-1 head is reproduced on the CH-4 head, the gap angle will be different. Therefore, a so-called azimuth loss, which can be found from equation (1), occurs.

■-1 Azimuth loss = 201 @ (dB)...
・(1)-(D-#) However, λ is the recording wavelength. ■For S standard 11 VTR, the gap angle, that is, the azimuth angle 0, is 12 degrees, [-] and the CH-1 head and CM-
The gap inclination angle of the two heads is +6 tl-6, respectively.
1. Therefore, in the frequency band of the video luminance signal (hereinafter simply referred to as the luminance signal), an azimuth loss of 306 or more (depending on the azimuth angle) can be obtained, and crosstalk can be sufficiently suppressed.

On the other hand, when the color signal frequency band is wide, the recording wavelength is long, and the azimuth loss is only about 10 dB. Therefore, in the azimuth recording method, crosstalk cannot be suppressed sufficiently, and the color phase shift recording method described below is adopted.

FIG. 2 is a schematic diagram showing the recording principle of color phase shift recording method 1, and FIG. 3 is a schematic diagram showing the principle during reproduction of the same method.

In these figures, the upper track is a track traced by the acH-1 head (hereinafter abbreviated as CH-1 rack), and the lower track is the track traced by ticH-2 head (hereinafter abbreviated as CH-2 rack). ), arrow X indicates the head running direction. In the following description, the left end H0 of each horizontal scanning period (hereinafter referred to as iH) is used as a reference.

In the color phase shift recording method, as is clear from Figure 2, when recording with CH-1) lag, IH
CM-
2) When recording with a rack, the phase t9 of the color signal for each IH
Delay by 0 degrees and play 1ilS.

On the other hand, during playback, if a CH-1 track is played back by an IfCH-1 head, the playback signal is delayed by 90 degrees for each IH, as is well known. As a result, the relationship between the main signal to be reproduced and the crosstalk becomes as shown in FIG. That is, the crosstalk component is I
H4111K: Has a phase difference of iao degrees.

' Here, regarding the video signal, since the IHmb signal has line correlation with almost the same content, each color signal AB of 1 rack of adjacent CH-1 and CH-2 AfI41 and B! II Bml+1
The relationship with A! I= Aa+1x or B@= B*+1
it is conceivable that.

IHj here! The X-shifted color signal and the color signal without delay are added to each of the CH-1) rack and CH-2) rack, and the signals of both tracks are added. In this case, CH-2 forming the crosstalk component
) If we pay attention to the fact that the rack signal is a phase shift every 111, we get equation (2).

(Am” Bm) + (in +1-1m+1) = 2
Aa "・"・"・"' (2) That is, while a color signal approximately twice as large as the main signal is obtained, the crosstalk components cancel each other out and are removed.

However, the conventional techniques described above have the following drawbacks when attempting to perform higher density recording.

In other words, in order to achieve high-density recording, considering the mechanical precision of track tracing by the head, the recording track width must be narrower than the head track width by the mechanical precision of the tracing to avoid mistracking. During recording, it is necessary to sequentially record (overwrite) parts of the recording tracks in an overlapping manner.

This overwriting width must be at least as accurate as the machine that traces the track, and is calculated by (head track width) - (jell) rack width → + (
overwriting width).

In such an E sickle that uses overwriting, if the track width' is narrowed to improve the recording density, it is extremely difficult to improve the track tracing accuracy. The ratio becomes smaller.

During playback, crosstalk components occur in the overwritten portion, so as the overwriting width becomes relatively large with respect to the recording track width, the crosstalk component with respect to the main signal becomes relatively large. .

Therefore, with respect to color signals, the conventional color-7Aze shift method, which makes full use of less-than-perfect correlation, has the drawback of not being able to cancel crosstalk components to a practical level. , the following methods can be considered.

α) Luminance signals are recorded continuously, but chrominance signals are recorded between 8 adjacent ones! ! Taking advantage of the strong correlation between
Record every INl.

During playback, the recorded color signal is output twice using an IH delay line, thereby compensating for the parts that are not reproduced.
, in this way a, II
@) The recording between the racks is arranged in a checkered pattern as shown in FIG. 4 (the shaded area in the figure indicates the color signal recording area). Therefore, the blank parts of the checkered pattern can function as mutual guard bands, and crosstalk can be eliminated.

However, as is clear from the above, this method has the drawback that the amount of information is reduced to 1/2.

Furthermore, the conventional techniques described above have the disadvantage that when recording at a higher density, the audio signal cannot be recorded satisfactorily.

That is, if one of the methods for improving the recording density is to further narrow the track width as described above, it is necessary to reduce the feeding speed of the magnetic tape. As a result, a sufficient audio band cannot be obtained by recording audio using a fixed head used in conventional VH8 standard VTRs.

One possible solution to this problem is to use a rotating head to record audio signals in a superimposed manner within a video track. However, as is clear from the frequency characteristics of the VTR, the audio and color signals recorded in a superimposed manner (hereinafter referred to as superimposed signals) cannot be set above the luminance signal frequency band. do not have.

As a result, the azimuth recording method has to be set in a long wavelength region where the azimuth effect is weak, and therefore a sufficient effect cannot be obtained with the azimuth recording method.

Furthermore, since there is no HMK correlation between the audio signals a and *, there is a drawback that crosstalk cannot be canceled even with the color phase shift method.

It is an object of the present invention to eliminate the above-mentioned nine drawbacks of the prior art, and to provide a high-performance magnetic recording device capable of high-density recording and reducing crosstalk from adjacent tracks, without missing information even in narrow video tracks. To provide a recording and playback method.

Furthermore, it is an object of the present invention to eliminate the problem of overlapping within a video track even for audio signals for which crosstalk cannot be canceled using phase 1lIW4 connections between adjacent horizontal scanning lines, such as video signals. Record it, and also next door! ) To provide a method for magnetically recording high-quality audio by reducing the image area of crosstalk from a rack.

In order to achieve the above object, the present invention employs the following method.

(1) Periodically compressing the time axis of a continuous signal to be recorded in a superimposed manner, converting the superimposed signal into an intermittent signal without reducing the amount of information, and recording the signal on a magnetic tape using a head. . On the other hand, the superimposed signal recorded on the adjacent track is similarly compressed on the time axis to form an intermittent recording pattern.

Furthermore, regarding the arrangement of the recording patterns, the time axis is compressed so that the recording patterns recorded intermittently between adjacent tracks are not adjacent to each other, that is, they are recorded in a checkered pattern or a striped pattern. do the
Also, as a control signal that changes the phase of recording timing between adjacent tracks. The standard signal is used as a reference.

(3) When the superimposed signals mentioned in (1) above are color signals and audio signals, and when these signals are time-axis compressed and recorded on magnetic tape, it is necessary to perform time-axis expansion when playing back them. Because of this, the luminance signal advances relatively,
The advance is compensated using, for example, a delay line.

Hereinafter, the present invention will be explained using the drawings.

FIG. 5 is an explanatory diagram showing an example of a recording pattern recorded on a magnetic tape by the method of the present invention.

In the same figure, the part with dots L1 is the recording track of the luminance signal by a 90H-2 head with a negative azimuth angle, and the part without dots is a CM-1 head with a positive 7 azimuth angle. There are two ways to record the luminance signal.

Further, the shaded area is the color signal recording area, and indicates the division of the thick solid line ridges IH.

The arrow X indicates the direction of rotation of the head, as in FIG. 2.3.

The CH-1 head runs on the magnetic tape in the direction of arrow X in order to record, for example, the first field of one frame, so it records a luminance signal and a chrominance signal. in this case,
The luminance signal is recorded continuously, but the color signal is
Performs twice the time axis compression on H@, and compresses the first half of IH by 1/2.
2 Record only during the H period.

The CH-2 head records the first field of one frame, performs R alignment, shifts by one video track, runs on the magnetic tape in the direction of arrow X, and outputs the luminance signal and color signal. Record.

In this case, the luminance signal is recorded continuously like the CH-1 head, but the color signal is recorded for each l
H45K time axis compression is performed, and recording is performed in the 1/2H period that is the opposite of the 0H-1 head.

By using the above recording method, a checkered recording pattern with no missing information as shown in FIG. 5 can be realized.

Next, the reproduction state of signals recorded on the magnetic tape as shown in FIG. 5 will be explained with reference to FIG. 11117.

Figures 7-) to (2) are diagrams showing the relationship between the spectral intensity (11 axis) and the frequency F (horizontal axis) of the recorded signal on the magnetic tape, and the figure (b) is in Figure 5. A diagram showing the relationship between the spectral intensity and frequency of the recorded signal at the part B2, Figure (e) is a diagram showing the relationship between the spectral strength and frequency of the recorded signal at the part B2 in Figure 5. A diagram showing the relationship between the spectrum intensity and frequency of the recording signal of the No part in Figure 5, same! ! 1(6) is a diagram showing the relationship between the intensity and frequency of the recorded signal at the location B2 in FIG. In these figures, 1. fyld indicates a luminance signal, and fc indicates a color signal.

If the CI (-1 head) traces and reproduces the AI part in the recording pattern of the CH-1 rack shown in Figure d, then the CH-1 head will have the data shown in Figure 7-). One spectrum signal is obtained as the main signal.

In this case, CH-1 Head Co., Ltd. simultaneously reproduces the recording signal of the section 13 in the track adjacent to the At section as a crosstalk signal. This crosstalk signal has a spectrum shown in (7).

Considering the cross F-reflection in this case, since the wavelength of the luminance signal component in the crosstalk signal is short, it can be sufficiently reduced by the azimuth effect. On the other hand 1. In the long wavelength color signal component for which the azimuth effect cannot be sufficiently expected, K does not exist there, as is clear from No. 7, and therefore there is no crosstalk problem.

Even when the CH-2 head traces and reproduces the part B2 in the recording pattern of the CH-2 rack shown in FIG. 5, as is clear from FIG. Similar to the relationship between A1 and B1 described above, no crosstalk occurs.

Also, 25 of M or B1 in Figure 5 (C and b in Figure 7)
- When reproducing a part for which no color signal is recorded, the time axis is expanded and lengthened by twice the time axis of the time axis compressed color signal of AI or B- (a and d in Figure 7). and then play it back.
As mentioned above, the lack of color signal in the Bl region means that
Not a problem.

In addition, it is possible to saturate the mesori by reproducing and writing in areas where color signals are recorded, and in this case, when reproducing areas where color signals are not recorded, 11 because it cuts off the memory and dies.
11) Crosstalk of the color signals from the 9x is not a problem.

Next, with reference to the drawings, methods for time axis compression during O recording and time axis expansion during playback in order to realize the recording butter shown in FIG. 5 will be explained.

8wJ is a block diagram showing an example of a signal processing N circuit that performs time axis compression during recording and time axis expansion during reproduction to realize the recording pattern shown in FIG. 5.

In the figure, 1 is the color signal input terminal, 2 is the first changeover switch, and the first variable delay memory (for example, BBD) from the three companies.
, COD, etc.), 4 is the second variable kite mesori, 5 is 1
12E) 'On/off switch, 6 is color signal output terminal, 7
10' are the first to 40th switches, 11 is a frequency af, an O clock circuit, 12 is a clock circuit with a frequency 2fo, which is twice the frequency f0, and 13
14 is an input terminal for a head switching signal, 15 is an input terminal for a horizontal synchronizing signal, and 16 is an input terminal for a recording/playback mode control signal.

The control signal generation circuit 13 generates control signals φ for the first and second changeover switches 2 and 50, which are determined by the head switching signal, the horizontal synchronization signal, and the recording/playback mode control F roll signal; φ, and the first to fourth switches 7 to 10 control signals ψ, to ψ6 are output.

FIG. 9 is a time chart showing an example of the timing of the horizontal synchronizing signal H8 and the control signals .phi.6 to .phi.6 in the case of silver printing with the CM-1 head.

At the same time as the horizontal synchronization signal H8O rises, the color signal input to the terminal IK is transferred to the first variable delay switch 2 via the first switch 2 controlled by the control signal φ1. It is input into memory 3. .

At this time, in the first variable delay memory 3, the control signals φ,
C) The clock circuit 11 is also operated to be written with the output clock via the first switch 7 which is controlled to be in the ON state. This write operation continues until the next rising edge of horizontal synchronizing signal H8, that is, I
The period of H is known. .

Simultaneously with the completion of the color signal writing operation described above, the control signal φ! As a result, the second changeover switch 5 is controlled to change fJb to the opposite side, and the first variable delay memory 3
When outputting the color signal written in the first variable delay memory 3, the control signal φ,
As a result, the time axis is compressed by 1/2 when recording onto the Oa tape. It is carried out in the first half of IH in a state where the

On the other hand, as is clear from the time chaff in FIG. 9, in the variable kite memory 4 of the irises 2, the first variable delay memory 3 performs the color signal O write operation using the output clock from the clock circuit 11 having the frequency f0. When doing this, the frequency 2f0
The time is compressed using the twice the clock outputted from the clock circuit 12, and the color signal readout operation is performed in the first half of IH.

Also, when the first variable delay memory 3 reads out the color signal at a clock rate of 92 times the clock outputted from the clock circuit 12 with the frequency 2f0, the variable delay memory 4 of Mori and Rattan 2 reads out the color signal with a clock frequency of 2f0. A color signal writing operation is performed using the output clock from the clock circuit 11.

FIG. 10 is a time chart showing an example of the timing of the horizontal synchronizing signal H8 and the above-mentioned control signals φ, to φ- when recording with the CH-2 head.

The difference between this FIG. 10 and the above-mentioned FIG. 9 is that the control signal number φ,
The timing of φ6 is 1s In the figure, the horizontal synchronizing signal H8 is at a high level (on state) in the first half of IH.

In contrast, Figure 10 shows that the level is high only in the latter half.

As a result, as shown in Figure 5, in the CM-1 head,
In contrast to OK, which records the color signal in the first half of the IH, in the CH-2 head that records and forms the Is contact track, the color signal is recorded in the second half of the IH. In this way, the color signal recording patterns of each track are prevented from being adjacent to each other.
It will be recorded in a checkered pattern.

During playback, the color signal is written into the memory using the clock output from the clock circuit 12 with a frequency of 2f, and the readout operation is performed using the clock circuit 12 with a frequency of fρ.
It is clear that the clock output from 1 can be used.

The above explanation has been given for the case where a color signal is recorded in a superimposed manner within a video track, but it can also be applied when an audio signal is recorded in a superimposed manner within a video track in a frequency band below the luminance signal frequency band. That is clear.

Furthermore, both the color signal and the audio signal can be time-base compressed and recorded. Figure 11 shows the method of the present invention.
FIG. 1 is an explanatory diagram showing an example of a nine-recording pattern in which both a color signal and an audio signal are recorded on a magnetic tape according to the method of the present invention.

As is clear from the figure, in this example, in the CM-1 rack recorded by the CM-1 head, its IH (1)
Record the "color signal" (the area where the dots were applied) in the first half, and
The audio signal (shaded area) is recorded in the latter half of H.

On the other hand, in the CH-2 rack recorded by the CH-2 head, the audio signal is recorded in the IHem half, and the color signal is recorded in the latter half.

In this way, when looking at the audio signal and the color signal for each part, even if they are recorded in a checkered pattern, their respective exclusive frequency bands are arranged in a parallel manner, so it is necessary to use a bandpass filter. By using this, it is possible to remove cross-F lines during reproduction from adjacent patterns.

In this embodiment, the luminance signal, the color signal, and the audio signal are recorded in the same area in quantity, but since the respective proprietary frequency bands are different, no problem arises on either side.

In the above explanation, the period of time axis compression during recording and time axis expansion during playback is IH, the compression ratio is 1/2, and the recording interval of the same recording signal compressed in the time axis between adjacent racks is Although the phase difference of the timing is set to 1/2H, the present invention is not limited to the above-mentioned case.

For example, as shown in figure ls6, color signals for 17 frames are transmitted over 1fl direct synchronization period, that is, 1 field period V(
If the data is compressed to a track period (not shaded), the period of time axis compression becomes one frame period F. That is,
In this case as well, it is possible to realize a striped recording pattern in which there is no loss of information, and the time-base compressed signals between tracks do not adjoin each other.

Therefore, it is clear that the period of time axis compression and expansion is not limited to IHK, but may be arbitrary. However, the 8th to 10th
Considering that by matching the timing of the control signal explained in the figure with the retrace period, it is possible to reduce noise and that the existing horizontal and vertical synchronization signals can be used as the reference for the control signal. It is effective to use a period that is a multiple of the horizontal and -direction synchronizing signals.

Furthermore, when the compression ratio is set to 172 or more, the phase difference in the recording timing of the time-axis compressed recording signals of nine identical racks between adjacent racks can also be arbitrarily changed according to the compression ratio. Furthermore, it is not necessarily necessary to perform H alignment of the time axis compressed nine recorded signals as shown in FIG. 5 and 111mK.

That is, the gist of the present invention is to compress the time axis of a color signal and/or audio signal without causing loss of information, and to prevent the time axis compressed signals from adjoining between adjacent tracks. The main purpose is to create a checkered or striped pattern.

Note that the audio signal is sampled during the blanking period of the horizontal synchronizing signal HaO, and the sampling value t17
By recording within 2H, a recording pattern can be formed so that audio signals do not overlap between adjacent tracks.

In this case, the number of stages of the first and second variable delay memories 3 and 4 in the block diagram of FIG. Circuit 12 also has frequency f6
It is equivalent to the 0 clock circuit 11 and can be made into a lock circuit.

That is, in this case Kd, the clock circuits 11 and 1
Since the period of 2 is IH, no time axis compression conversion is performed, but according to the Nyquist 0 theorem, for a horizontal scanning frequency of about 15IGk, the checkered pattern can be applied without losing audio information up to about 7KHS. It is possible to record patterns.

Furthermore, according to the present invention, when a color signal and an audio signal are compressed in the time axis and recorded in a superimposed manner with respect to a luminance signal, there is no difference between the chrominance signal and the audio signal with respect to the luminance signal during playback. arise. It is therefore necessary to compensate for the aforementioned deviations by appropriately delaying the luminance signal by well-known methods, for example by using delay lines.

From the above explanation, it is clear that according to the present invention, even if there is a narrow video track, there is no missing information,
11I) It has become possible to perform high performance magnetic recording with high ** recording without causing crosstalk in the rack interleaving.

Moreover, especially in the present invention, adjacent H signals such as Eirin signals
Even for audio signals whose crosstalk cannot be canceled by using the correlation between them, it is possible to record them in a superimposed manner within a video track without causing crosstalk between adjacent tracks. -t'' has the effect of obtaining high-density recording with high quality sound.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the principle of the azimuth recording method, Figure 2 is a schematic diagram showing the recording principle of the color phase shift method, and Figure 3 is a schematic diagram showing the recording principle of the color phase shift method.
Figure 4 is an explanatory diagram showing an example of a conventional recording pattern in which superimposed color signals are checkered, and Figure 5 is a schematic diagram showing the principle of reproduction of t. FIG. 6 is an explanatory diagram showing a first example of the recording pattern recorded on the magnetic tape, and FIG. Fig. 7 is a diagram showing the relationship between the spectrum intensity and frequency O of the recording signal on the magnetic tape in Fig. 5, and Fig. 8 shows the time axis compression during the ninth recording to realize the recording pattern shown in Fig. 5. A block diagram showing an example of a signal processing circuit that performs time axis expansion during playback. FIG. 9 is a block diagram showing an example of a signal processing circuit that performs time axis expansion during playback. The control signal φ shown in FIG. ~A time chart showing an example of the timing of φ6, /'
FIG. 11 is an explanatory diagram showing a second example of a deployment pattern recorded on a magnetic tape by the method of the present invention. 1 selector switch, 3... first variable i1 delay memory, 4... second variable delay memory, 5...
・Second changeover switch, 7 to lO...1st to 4th
switch ζ 11...clock circuit with frequency f,
12... Clock circuit with a frequency of 2f, 13... Control signal generation circuit. Agent Benhoshi Hiramoto Michihito Figure 1, Direction of travel Figure 2 Figure 3 Figure 411 Figure 511 Figure 6 Figure 11 Figure γ Figure 8

Claims (1)

[Claims] 0) A video luminance signal is continuously recorded on a magnetic tape,
and a signal recorded in a superimposed manner on the video luminance signal (
The superimposed signals (hereinafter abbreviated as superimposed signals) are compressed on the time axis at a desired magnification without losing the amount of information, and the superimposed signals compressed on the time axis are intermittently A magnetic recording method characterized by recording. 12) The magnetic recording method according to claim 1, wherein the superimposed signal is a color signal. C3) The magnetic recording method according to claim 1, wherein the superimposed signal is an audio signal. (4) The magnetic recording method according to claim 1, wherein the superimposed signals are a color signal and an audio signal. G) A video luminance signal is recorded continuously, and the superimposed signal is recorded in a superimposed manner on the video luminance signal, and the superimposed signal with no loss of information is compressed on the time axis at a desired magnification and is compared to adjacent tracks. In a method for reproducing a magnetic tape that is intermittently recorded so that they are not adjacent to each other, the brightness signals read from the magnetic tape are continuously recorded during one horizontal scanning period.
By writing the superimposed signal read from the magnetic tape into the memory at a clock according to the time axis compression magnification, all of the luminance signal and superimposed signal for one horizontal scanning period are A magnetic reproducing method characterized in that the luminance signal and the superimposed signal are written in a memory, and then read out and reproduced from the memory simultaneously and continuously during one horizontal scanning period. (6) The magnetic reproduction method according to claim 5, characterized in that the superimposed signal is a color signal; and (7) Claim 5, characterized in that the superimposed signal is an audio signal. The magnetic reproduction method described. Ql) The magnetic reproduction method according to claim 5, characterized in that the superimposed signals are a color signal and an audio signal.