JPH0474301A - Digital magnetic recording/reproducing method - Google Patents

Abstract

PURPOSE:To reduce the deterioration of a reproduced picture quality by reproducing the data (think blocks) at the same timing by adjacent magnetic heads at the time of variable speed reproduction in a multi-channel recording system. CONSTITUTION:Plural magnetic heads are placed adjacently on a rotary cylinder so that recording and reproduction are executed by winding a magnetic tape around this rotary cylinder, and digital magnetic recording and reproduction are executed so that data recorded through this magnetic head becomes the same phase relation with regard to a think block. That is, the magnetic head 1 and 2 become the same phase with regard to the think block on the magnetic tape, and the moment the magnetic head 1 traces on the tip 7 of the think block, the magnetic head 2 also traces on the tip 8 of the think block. In such a way, at the time of variable speed reproduction in multi-channel recording, such a defect as data can be reproduced only unsymmetrically between the magnetic heads is improved and deterioration of a reproduced picture quality is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to magnetic recording, particularly to a digital magnetic recording and reproducing method.

Conventional Technology Various recording and reproducing devices using magnetic tape as a recording medium have been developed and put into practical use. For example, the video tape recorder (hereinafter referred to as "VTR") is a typical example, and in recent years home VTRs have become widespread. has increased significantly, and its performance has improved significantly.

On the other hand, in recent years, demands for higher image quality have increased in the field of video equipment, and various methods have been adopted. Recently, due to rapid advances in semiconductors, research has been conducted into digital recording VTRs (hereinafter referred to as "DVTRs") that digitally process video signals and record them as digital data on magnetic tape.
It is beginning to be put into practical use in some areas.

The conventional DVTR system will be explained below with reference to the drawings.

FIG. 4 is a block diagram showing a conventional example. In the figure, 29 is a video signal input terminal, 37 is a video signal output terminal,
30 is a digital processor, 31 to 34 are magnetic heads, 3
6 is a magnetic tape, and 35 is a rotating cylinder.

The video signal to be recorded is applied to the digital processor 30 via the video signal input terminal 29. Digital processor 3
After performing various processing at 0, the signal is applied to the magnetic heads 31 to 34. The magnetic heads 31 to 34 are mounted on a rotating cylinder 35 and record signals on a magnetic tape 36 while rotating.

Problems to be Solved by the Invention Various problems occur when trying to perform variable speed playback by changing the tape speed on a VTR.

FIG. 5 is a diagram showing the trajectory of the magnetic head when performing variable speed reproduction using the method shown in FIG. In the figure, 38 is a magnetic tape, 39 to 41 are tracks, 42 and 43 are magnetic heads, and 44 and 45 are trajectories of the magnetic heads 42 and 43. Magnetic tape 38 and magnetic heads 42, 43 correspond to magnetic tape 36 and magnetic heads 31, 32 in FIG. 4, respectively. Since FIG. 4 shows helical scan recording, tracks 39 to 41 are created diagonally on the magnetic tape 38, but in order to simplify the drawing and explanation, tracks 39 to 41 are created at right angles to the longitudinal direction of the magnetic tape 38. Track 39-4 in the direction
1 is illustrated.

Furthermore, it is mechanically impossible to mount the magnetic heads 42 and 43 completely adjacent to each other on the rotary cylinder 35, so they are mounted with a slight gap between them. Therefore, the positional relationship between the magnetic heads 31 and 32 on the magnetic tape 36 is, for example, magnetic heads 42 and 43. When variable speed reproduction is performed in such a state, the trajectories of the magnetic heads 42 and 43 on the magnetic tape 38 become as shown by 44 and 45, respectively.

The situation in FIG. 5 will be further explained in conjunction with FIG. 6. In the figure, 48 and 49 are tracks, 46 and 47 are magnetic heads, 50 to 63 are the head positions of sync blocks, and 54 and 5 are magnetic heads.
5 is the sync block length. Also, tracks 48 and 4
9. The magnetic heads 46 and 47 are respectively connected to the trunk 3 in FIG.
9 and 40, corresponding to magnetic heads 42 and 43.

In this figure, the leading positions 250 (51) and 52 (53) of the sync blocks between tracks 48 and 49 are not aligned. Furthermore, the magnetic heads 46 and 47 are not in the same positional relationship with respect to the sync block.

FIG. 7 shows the reproduction signal when the magnetic heads 46 and 47 scan the trajectories 44 and 45 by variable speed reproduction as shown in FIG. 5 in the above state.
6 is the envelope of the reproduction signal reproduced via the magnetic heads 46 and 47, 58 is the zero level, 57 is the lower limit of the reproducible reproduction level of data, 59 is the period during which the data can be reproduced, and 60 is the envelope from the magnetic head 46. A data string to be reproduced, 63, a data string to be reproduced from the magnetic head 47, 54
and 55 is the sync block length, the shaded part 60 is the sync block in which data is restored, 61 and 64 are the beginnings of the sync block, and 66 to 70 are times. Since the magnetic heads 46 and 47 in FIG. 6 trace like the trajectories 44 and 45 in FIG. 5, the envelope of the signals reproduced from the magnetic heads 46 and 47 fluctuates as shown in 56. By the way, data can be reproduced only when a signal larger than the lower limit level 57 is obtained, so it is limited to the periods from times 67 to 68, from times 69 to 70, and so on, as shown in 57. On the other hand, the information is usually meaningful in units of sync blocks, and if there are some parts of the sync block that cannot be restored to correct data, the entire sync block becomes invalid. Therefore, the sixth
60 regarding the information reproduced from the magnetic head 48 in the figure.
Sync blocks with diagonal lines like this can be used as meaningful data. However, the magnetic head 47 in FIG.
As for the information played from 63, from time 67 to
68, the sync block may not be completely included in the period from time 69 to time 70... and no meaningful data can be obtained.Depending on the relative relationship between the magnetic heads 46 and 47 and the magnetic tape, the magnetic Naturally, there are cases in which data can be reproduced from the head 47 but data cannot be obtained from the magnetic head 46.

In general, in multi-channel recording, between magnetic heads that are closely spaced, adjacent (or identical) areas on the screen are often divided and recorded in adjacent locations on the magnetic tape.
If data can only be reproduced inconsistently between magnetic heads in this way, the reproduced screen will often deteriorate.

Means for Solving the Problems Therefore, in the present invention, in order to solve the above problems, a plurality of magnetic heads are arranged close to each other on a rotating cylinder, and a magnetic tape is wound around the rotating cylinder to perform recording and reproduction. The authors have proposed a method for digital magnetic recording and reproduction in which data recorded via the above-mentioned magnetic head has the same phase relationship with respect to synchro blocks.

By doing this, the defect that data can only be reproduced inconsistently between magnetic heads during variable speed reproduction in multi-channel recording is corrected, and deterioration of the reproduced screen is reduced.

Example An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a recording pattern and a magnetic head according to an embodiment of the present invention. In the figure, 3 and 4 are the tracks, 1 and 2 are the magnetic heads, 5 to 9 are the head positions of the sync blocks, 10 and 11 are the sync block lengths, and 12 is the distance between the magnetic heads 1 and 2. be. The names of these parts are the same as in FIG. 6, and the differences from FIG. 6 will be mainly explained. In the case of this embodiment, unlike FIG. 6, the magnetic helads 1 and 2 are in the same phase with respect to the sync block on the magnetic tape. That is, the magnetic head l
At the moment when the magnetic head 2 is tracing over the tip 7 of the sync block, the magnetic head 2 is also tracing over the tip 8 of the sync block.

FIG. 2 shows the state of the reproduced signal when the magnetic heads 1 and 2 scan the trajectories 44 and 45 by variable speed reproduction as shown in FIG. 5 in the state of the above-described embodiment. In FIG. 2, 13 is the envelope of the reproduction signal reproduced through the magnetic heads 1 and 2, 15 is the zero level, 14 is the lower limit of the reproducible level of data, and 16 is the period during which the data can be reproduced. , 17 is a data string reproduced from the magnetic head 1,
18 is a data string reproduced from the magnetic head 2, 19 and 20 are sync block lengths, the hatched portions are sync blocks from which data is restored, and 21 to 24 are times. Each of these is explained in FIG. 7, so the differences from FIG. 7 will be mainly explained. The difference from FIG. 7 is the difference between numbers 18 and 63. Since the magnetic heads 1 and 2 trace as trajectories 44 and 45 in FIG. 5, the envelope of the signals reproduced from the magnetic heads 1 and 2 fluctuates as shown in 13, and the data that can be reproduced is approximately as shown in 16. Time 21~
22, time 23-24, . . . On the other hand, regarding the information reproduced from the magnetic head 1 in FIG. 1, the shaded sync blocks 17 are completely restored in units of sync blocks, so that they can be used as meaningful data.

Furthermore, as shown in the explanation of FIG. 1, since the magnetic head 1 and the magnetic head 2 are set to have the same phase with respect to the sync block on the magnetic tape, the information reproduced from the magnetic head 2 in FIG. As shown, the sync blocks in the shaded areas become available as meaningful data during the periods 21-22, 23-24, . . . . Naturally, the sync block lengths 19 and 20 are completely included between time 21 and time 22.

As already mentioned, in multi-channel recording, magnetic heads that are clustered closely together often divide adjacent (or identical) areas on the screen and record on adjacent locations on the magnetic tape. By making it possible to simultaneously reproduce data at approximately the same position between magnetic heads, deterioration in the image quality of the reproduced screen is reduced.

Next, the state of the rotating cylinder in this embodiment will be shown together with FIG. 3. In the same figure, 27 is a rotating cylinder, 25 and 26
is a magnetic head, and 28 is a distance. Magnetic heads 25 and 26 correspond to magnetic heads 1 and 2 in FIG. 1, respectively. The magnetic heads 25 and 26 are fixed on a rotating cylinder 27, and as the rotating cylinder 27 rotates, helical scan recording is performed. By the way, the distance 28 is the magnetic head 2
This is the distance between the gap No. 5 and the gap of the magnetic head 26 on the rotational circumference. This distance 28 is equal to the distance in the track direction on the magnetic tape. Therefore, this distance 28 and the distance M12 in FIG. 1 are set to equal values.

The present invention has been described above along with one embodiment.

In short, the present invention takes into consideration that data (sync blocks) are reproduced at the same timing in adjacent magnetic heads during variable speed reproduction using a multi-channel recording method. Furthermore, data that is reproduced at the same timing (sync block)
are placed close to each other on the magnetic tape and on the screen.

Effects of the Invention As is clear from the above explanation, the present invention can simultaneously reproduce data at almost the same position between magnetic heads during variable speed playback of multi-channel recording, thereby reducing deterioration in the image quality of the playback screen. .

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a tape pattern and the position of a magnetic head showing one embodiment of the present invention, FIG. 2 is an explanatory diagram showing a reproduction state when variable speed reproduction is performed in FIG. 1, and FIG. An explanatory diagram showing the rotary cylinder and magnetic head to realize the state shown in Figure 1, Figure 4 is a block diagram showing the conventional system,
Fig. 5 is an explanatory diagram showing the trace state of the magnetic head during variable speed playback, Fig. 6 is an explanatory diagram showing the tape pattern and magnetic head position showing a conventional example, and Fig. 7 is an explanatory diagram showing the position of the magnetic head in variable speed playback in Fig. 6. FIG. 3 is an explanatory diagram showing a reproduction state when 1, 2.25.26...Magnetic head, 3.4
...Track, 5-9...Start of sync block, 10°11, 19.20...Sink block length, 27...Rotating cylinder, 28・
·····distance. Name of agent: Patent attorney Shigetaka Awano Hakaichimeika 6 Figure B q Figure 2/9! Figure 7 Z/2? ? 3 δ≠ , <J me3 do2 7θ

Claims (2)

[Claims] (1) A plurality of magnetic heads are arranged close to each other on a rotating cylinder, and a magnetic tape is wound around the rotating cylinder to perform recording and reproduction, and the data recorded via the magnetic heads is transferred to a sync block. A digital magnetic recording and reproducing method characterized in that the same phase relationship is achieved as much as possible. (2) A plurality of magnetic heads are disposed close to each other on a rotating cylinder, and a magnetic tape is wound around the rotating cylinder to perform recording and reproduction, and the magnetic heads are formed on the magnetic tape. A digital magnetic recording and reproducing method characterized in that sync blocks are arranged on a recording pattern so as to have the same phase relationship.