JPS61150476A - Reproduction system of video signal - Google Patents

Abstract

PURPOSE:To decrease both the maximum deviation of a rotary magnetic head for reproduction and the overlap amount of a tape winding angle around a tape guide drum, by shifting a magnetic head in the direction approximately orthogonal to a sloping track and scanning plural sloping tracks in the order opposite to a recording mode for reproduction of recording signals. CONSTITUTION:In a figure 1 the areas enclosed by the broken lines show the sloping tracks where the digital signals are recorded. The figures A-D show four tracks which forms a sheet of field to be reproduced in the order of A-D. Here a DT head is moved for scanning in the order of 1-4 and four tracks are reproduced, that is, the tracks D, C, B and A are reproduced in the loci 1, 2, 3 and 4 respectively. Thus the video signals equivalent to a field are obtained. In this case, the maximum deflection width HDT of the DT head is set as shown in a figure 2 for each reproduction speed (including still and forward reproductions) as well as reverse reproduction) VT. In other words, the width HDH is reduced to the same speed VT in comparison with conventional values in case the reverse reproduction speed VT is less than 0.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video signal reproduction system that enables reverse reproduction.

[Conventional technology]

As many as digital VTRs! If you want to record omnivore,
It is almost impossible to record one field of video signals on one inclined track. Therefore, it is necessary to record one field of video signals by dividing them into a plurality of inclined tracks.

This formation of multiple tracks in one field is achieved by providing multiple recording (reproducing) rotary magnetic heads and multiple rotations.

That is, if the number of recording heads that a VTR has is NH, and the number of revolutions per field of the tape guide drum on which these heads are mounted is FD (rotations/field), then the video signal of one field is: NT=NHXFD ()U7ri/Field] ---
-(It will be divided into 11 tracks and recorded on the magnetic tape.

In this way, the digital video signal recorded on the magnetic tape by dividing the screen can be reproduced using a rotating magnetic head for variable reproduction (the head chip is mounted in a bimorph type and can be deflected in a direction approximately perpendicular to the inclined track). DT head) for variable speed playback, the video signal for one field,
That is, N7 tracks shown in equation (1) must be continuously reproduced. At this time, control of the DT head is actually achieved by moving the height of the DT head. The maximum swing width of this head is track pitch T
P and playback speed (tape running speed during playback) are determined by VT, and generally the maximum swing width increases as the distance from 1x speed playback increases. Therefore, the variable speed reproduction range is determined by the maximum possible swing width of the DT head, or conversely,
The required maximum swing width of the DT head is determined from the variable speed playback range.

Furthermore, as the height of the DT head changes, its scanning locus changes accordingly, so in order to ensure head-to-tape contact even at speeds below 1x, the mechanical tape winding on the drum is performed at the corners of the DT head. An amount of overlap corresponding to the maximum swing width is required.

FIGS. 7 and 9 show the relationship between the track and the head trajectory when the DT head is controlled using the conventional method. The number of recording heads in both FIGS. 7 and 9 is when Nu =: 1,
If Nu is 2 or more, the maximum swing width HDT of the head will be N1 times the value shown. The drum rotation speed is Fn in Figure 7.
= 4 (rotation/field), Fig. 9 is Fp = 3
(rotation/field) and a to dVc respectively show cases where the reproduction speed vT is 0 times speed (methyl), -1 times speed, -2 times speed, and -3 times speed.

In FIG. 7, the areas surrounded by each broken line indicate inclined tracks on which digital video signals are recorded; (A);
(B), (C), and (D) indicate four tracks constituting one field to be reproduced in this order. α indicates the tape running direction. At this time, the DT head moves to scan the tracks in the order of ■, ■, ■, ■, and tracks A on the trajectory of ■, B on the trajectory of ■, and B on the trajectory of ■.
Then, reproduce D with C9■ to obtain a digital video signal for one field. The maximum swing width HDT of the DT head at this time
As shown in Fig. 8 for each playback speed VT, HDT = NHX (4X IVT -11) XTp[
μm] (FD=4) (2). Note that FIG. 8 also includes the cases of still playback (vT=o) and forward playback (Vt>O).

Similarly, in FIG. 9, tracks (A) and (B)
, (C) constitutes one field in this order 3
Of the tracks in the book, the DT head sequentially plays track A on the trajectory of ■, B on ■, and C on ■ to obtain data for one field. The maximum swing width HDT of the DT head at this time is as shown in Fig. 10 for each playback speed VT: HDT = Nu X (3XIVT -11)XTP
(,!l?FL] (FD = 3) (3).

Generally, when the drum rotation speed is FDC rotation/feed, the equations (21, (31) are expressed by the following equations.

HDT = Nu X FD XIVT -11X T
P(/J7Fl]...(4) [Problem to be solved by the invention] As described above, in the case of reverse playback in the conventional playback method, D
The maximum swing width of the T head is large (and the associated tape winding around the drum has the disadvantage that the amount of corner overlap becomes large).

The present invention has been proposed in an attempt to solve these drawbacks.

[Means for solving problems]

The video signal reproducing method according to the present invention uses a rotating magnetic head for reproducing when reproducing a magnetic tape on which one field of video signals is divided into a plurality of inclined tracks and is played back in a direction different from that during recording. This method is characterized in that the recording signal is reproduced by scanning a plurality of inclined tracks in the reverse order to that during recording by shifting in a direction substantially perpendicular to the inclined tracks.

[Effect]

According to the present invention, the maximum swing width (positioning deviation) of the reproducing rotary magnetic head during reverse reproduction is reduced, and thereby the amount of overlap of the magnetic tape with respect to the drum can be reduced.

〔Example〕

FIGS. 1 and 3 show the relationship between the track and the head trajectory when the DT head is controlled by the method of the present invention. The number of recording heads is in the case of Nu=1 in both FIGS. 1 and 3, and N
When H is 2 or more, the maximum swing width HDT of the head becomes the value NH@K shown in the figure. The drum rotation speed in Figure 1 is Fp=
4 (rotation/field), Fig. 3 is FD = 3 [rotation/field], and playback speed vT is shown in a and d, respectively.
The cases where is 0x speed, (still), -1x speed, -2x speed, and -3x speed are shown.

In FIG. 1, the areas surrounded by broken lines indicate inclined tracks on which digital video signals are recorded, among which (A)
, (B), (C), and (D) are four tracks constituting one field to be reproduced in this order. At this time, the DT head is ■,■.

The movement moves to scan the tracks in the order of ■ and ■, respectively, and the trajectory of ■ is track D, the path of ■ is C2, and the path of ■ is B.

In (2), the four tracks are played back in the reverse order of A and the case shown in FIG. 7, and a video signal for one field is obtained. At this time, the maximum swing width HDT of the DT head is as shown in Fig. 2 for each playback speed (including reverse playback, still playback, and forward playback) VT. (5) In other words, during reverse playback (V<O),
Compared to the conventional equation (2) shown in FIG. 7, the maximum swing width HDT of the head is smaller for the same reproduction speed VT.

Similarly, in Fig. 3, tracks A, B, and C are three tracks that constitute one field in this order, and DT
The head sequentially reproduces three tracks in the reverse order of that shown in FIG. 9, with track C9 being B at track C9, and A at C9, in the reverse order of the case shown in FIG. 9, and data for one field is obtained. At this time, the maximum swing width HDT of the DT head is as shown in Figure 4 for each playback speed (including reverse playback, still playback, and forward playback) VT. That is, during reverse playback (VT<0), the maximum swing width HDT of the head is smaller for the same playback speed VT compared to the conventional equation (3) shown in FIG.

Generally, when the drum rotation speed is FDC rotation/feed x do], equations (5) and (6) are expressed as the following equation (7).

(7) Therefore, in such a split-screen recording method, as shown in FIGS. 5 and 6, FIGS.
When the characteristics shown in Figure 0 are combined, that is, when variable speed playback is performed using a DT head, one field's worth of tracks are played back in the original order as before during still and forward playback, and during reverse playback, the track is played back in the original order. With this method (by reproducing one field's worth of tracks in the reverse order from the original, the maximum swing width of the DT head can be reduced for the same playback speed during reverse playback. (No. 5) (See Figure and Figure 6)
. That is, for the same variable speed range, the required maximum swing width of the DT head can be small, and furthermore, the amount of overlapping of the corners of the tape corresponding to the swing width of the DT head can be reduced. Or conversely, the variable speed playback range can be widened with respect to the maximum possible swing width pressure of the same DT head.

Note that when controlling the DT head during reverse playback using this method, the tracks for one field are played back in the reverse order, so in order to process this in the correct order, the playback system has one A memory is required to store data for one field (more precisely, (one field) - (one rotation of the head)).

〔Effect of the invention〕

According to the method of the present invention described above, it is possible to reduce the maximum deviation amount (maximum swing width) of the rotary magnetic head for reproduction, which can be displaced in a direction substantially perpendicular to the inclined track during reverse reproduction. Wrapping the tape around the tape guide drum can reduce the amount of corner overlap. or,
Conversely, the variable range of reverse playback can be widened for the same maximum deviation of the magnetic head.

[Brief explanation of the drawing]

1 and 3 are pattern diagrams showing the track patterns on the magnetic tape of each embodiment of the method of the present invention, and FIG.
4, 5 and 6 are characteristic curve diagrams for explaining each embodiment of the present invention, FIGS. 7 and 9 are pattern diagrams showing track patterns on a conventional magnetic tape, and FIG. 1 and 10 are characteristic curve diagrams for explaining the conventional system. Figure 1 1 Field-1) Buttocks Figure 2 Figure 3 Figure 4 Figure 7 Figure 17 Figure 8 Figure 9 174 Figure 10

Claims (1)

[Claims] When a magnetic tape on which one field of video signals is divided and recorded on a plurality of inclined tracks is played back by running in a direction different from that during recording, the rotating magnetic head for reproduction is moved in a direction approximately perpendicular to the inclined tracks. A method for reproducing a video signal, characterized in that the recorded signal is reproduced by scanning the plurality of inclined tracks in the reverse order to that during recording.