JPS63194494A - Video signal recording method - Google Patents

Abstract

PURPOSE:To attain a variable speed reproduction with a simple processing by dividing a video signal obtained by time base multiplexing a chrominance signal to a luminance signal into two channels in a helical scan VTR, simultaneously recording two tracks in one scanning and recording one field by N times of sequential scannings. CONSTITUTION:A color sequential time compressed integration (TCI) signal is shown in a drawing. This is a high vision signal consisting of 1125 scanning lines for one frame and the effective lines of a first field are constituted of a 40th line to a 557th line and the effective lines of a second field are constituted of a 603th line to a 1120th line. In the drawing, numerals indicate line numbers. On the chrominance signal, Cws and Cns simultaneously appear. The one field of this signal is divided into three segments. The heads 2, 2' among the pairs of heads 2, 2' and 3, 3' have azimuth angles different from each other and the heads 2, 3 and 2', 3' have respectively the same azimuth angles.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applied to a helical scan video tape recorder (hereinafter referred to as VTR) when recording a wideband video signal.
The present invention relates to a segment recording method recording method in which one field is divided into multiple tracks and recorded.

Conventional technology Rotating two-head helical scan videotape recording is a technology employed in many VTR systems, typified by the VH8 and β systems.

The basic configuration, recording format, and recording/playback screen of this system are shown in FIGS. 7, 8 (&), and (b), respectively.

In FIG. 7, 1 is a magnetic tape, 2.3 is a magnetic head,
4 is a rotating drum. In FIG. 8 (?L), 5 is the recording track, T is the tape running direction, and H is the head moving direction. One recording track is recorded by the magnetic head 2 or 3 while the rotating drum rotates 180 degrees.

Therefore, P is the distance that the magnetic tape travels during one frame (two fields) when the recorded signal is 2:1 interlaced. Points A, B, C, and D correspond to person B, C, and D in Figure 8). As described above, in this system, one field of video signal is basically recorded on one track, and the number of revolutions of the drum is equal to the frame frequency.

2 designed to record NTSC video signals.
In order to record a wider band video signal, such as a no-vision signal, using the mechanical system of a head helical scan VTR, the input signal is divided into multiple channels and recorded.

@) To increase the relative speed of the head and tape, increase the rotation speed of the drum attached to the head.

There are two methods. In order to achieve the above-mentioned problem, it is only necessary to decide whether to adopt method (support) or method 0) or both, depending on the balance between the input signal bandwidth and the mechanical strength of the VTR. If method (a) is adopted, it will inevitably become a method called the segment recording method.

The case of the two-segment recording method will be explained below.

In order to record a signal with twice the band of the NTSC signal, it is necessary to rotate the rotating drum at twice the number of revolutions.

It is also necessary to double the tape running speed. The recording format and screen at this time are shown in FIG. 9 (IL), Φ). In this case, P' is the distance that the magnetic tape travels during one field.

SG1 and SG2 are segments obtained by dividing one field into two.

In this way, in the case of the two-segment system, one field of video signal is divided into two segments, and each segment is recorded on a separate track.

The problem that the invention aims to solve The problems with this method are as follows.

(To) In the case of variable speed playback in which a plurality of tracks are played back, such as slow, still, fast forward, etc., the SG1 and SG2 segments are mixed and played back in one screen.

(a) In general, the reproduction output of the RF signal of a VTR is unstable at the end of the tape. Therefore, the SN ratio of the reproduced signal corresponding to that portion becomes unstable. With this method, this part appears in the center of the screen.

The above two problems will be explained in detail.

The first problem is as follows.

FIG. 10 is a recording pattern diagram in the case of the segment method shown in FIG. 9. Here, 6 and 6' are each 1000
These are the trajectories drawn on the tape by the two heads at the same position when the tape feed speed is 4 times faster.

F1 to F8 in FIG. 10 show how the first to fourth fields are reproduced at normal tape speed. Furthermore, the hatched portions S and -S8 in this figure indicate the portions where the locus 6.6' of a is reproduced when the speed is 4 times faster. FIG. 10C shows one screen that is played back at 4x speed. This screen is a unit of W-width band-shaped image of the entire screen, with the upper half image and the lower half image alternately exchanged, and it is difficult to distinguish the image content.

The above is an example of 4x high-speed playback, but any n
The same is true in the case of variable speed reproduction of double speed or 17n times speed, and a screen is reproduced in which the locations on the screen are jumbled in segments. Furthermore, as is clear from the above description, the order in which segments are played varies depending on the tape running speed. Therefore, even if you try to obtain a correct playback screen by performing appropriate processing during playback, you will have to perform different signal processing depending on the tape running speed.
It becomes very complicated.

The second problem becomes noticeable in the following cases.

The envelope of the VTR's RF playback signal is often
The shape will be as shown in the figure. The figure shows an envelope for two segments, and A, B, C, I) correspond to the respective positions in FIG. This is because, as mentioned above, the contact between the head and the tape at the edge of the tape becomes unstable. As a result, a portion B with a poor SN ratio and a portion C with a good SN ratio exist adjacent to each other in the center of the playback screen. This phenomenon gives the impression that the image quality is worse than it actually is.

The above explanation has been based on the two-segment method, but these problems become more serious as the number of segments increases. That is, for the first problem, more segments will be played in a jumbled manner, and for the second problem, more seams will appear on the screen.

An object of the present invention is to provide a video signal recording method that does not have such problems.

Means for Solving the Problems The present invention solves the drawbacks of the segment recording method by line-sequentially generating the first and second color signals from a video signal consisting of a luminance signal and first and second color signals. When the signal is compressed, time-axis compressed, and time-axis multiplexed to the luminance signal, the signal is expanded by approximately twice the time axis, divided into two channels, and simultaneously recorded on two tracks, and one field is sequentially recorded by N scans. , the first color signal and the second color signal are applied to both of the above two tracks.
color signals are recorded at approximately equal intervals, and for all 2N tracks constituting one field, the color signals are recorded continuously from the scan start position to the scan end position on the track, from the start to the end of the screen. Scanning lines are recorded sequentially.

Effects of the present invention With the above-described configuration, in the case of variable speed playback, a normal screen can be obtained by performing relatively simple processing.
Furthermore, even if the head of one channel becomes clogged, it is possible to obtain a screen with a normal hue.

Embodiment Next, a first embodiment of the present invention will be described with reference to FIGS. 1 to 4.

In this embodiment, there are 1125 scanning lines and a field frequency of 60.
The H2 (2:1 interlaced) no-vision signal, which has a bandwidth approximately six times that of NTSC, is divided into two channels by time-axis expansion, and a pair of two-channel heads are placed on a rotating drum at 180 Hz. The number of drum rotations is recorded as 90112 on a rotating head helical scan VTR mounted at an angle.

FIG. 1 shows this embodiment. Figure e) shows a recording pattern on the magnetic tape, where 1 is the magnetic tape and T1-T12 are recording tracks. Horizontal scanning line numbers forming tracks T1 to T12 are shown in (b).

Below, the process of creating the combination of scanning lines shown in FIG. 1(b) will be explained in detail.

The high-definition signal includes a luminance signal (Y) and a color signal (Cw).

Cn) consists of three components. To multiplex these signals into one channel signal.

■ A method that uses color subcarriers to generate composite video signals, H
LO-PAL (Half' 1ine offs
et-PAL) ■ TCI method, which compresses the time axis of the color signal and multiplexes it on the horizontal blanking of the luminance signal, (Tinθc
There is an impressed integration. Among these, method (3) is considered to be a promising method because narrowband transmission is possible by transmitting color signals line-sequentially.

A color line sequential TCI signal is shown in FIG. This is made up of 1,126 scanning lines per frame... In the Evision signal, the effective lines of the first field are from the 40th line to the 657th line, and the effective lines of the second field are from the 603rd line to the 1,120th line. In the figure, the numbers indicate line numbers.

FIG. 3 is a diagram illustrating the process of time-axis expanding this signal and dividing it into two channels. this is.

Although only the first part of the first field is shown, the same applies to other parts. As for the color signal, it is arranged so that both 0w and on can appear at the same time. One field of this signal is divided into three segments according to the rules shown in FIG. 1(b). In the figure, 81 is a first segment consisting of a first track TI and a second track T2. Similarly, each segment consists of two tracks. Also, the first field is 31, S2, 33
゜The second field is s4. It consists of three segments each, ss and se.

Furthermore, FIG. 1(C) shows the configuration of the rotating drum used in this embodiment. In the figure, 4 is a rotating drum, 2.degree. 2' is a set of heads for simultaneously recording signals divided into two channels, and 3.3' is another set of heads. Here, the heads 2 and 2' have different azimuth angles, and the heads 2 and 3 and 2' and 3' have the same azimuth angle.

T1. T2 is simultaneously recorded by 2.2' and T3
, T4 are simultaneously recorded by 3.3'.

When recorded in this way, every track has a scan line at the top of the screen at the bottom of the tape, a scan line further down as it progresses on the tape, and a scan line at the bottom of the screen at the top of the tape. It will be recorded.

When a pattern recorded in this manner is reproduced, the reproduced screen is conceptually shown in FIG. 4. e) is the original screen to be recorded, and (b) is the reproduced screen. From the screen in (b), by relatively simple processing (2L
) screen is obtained. In the case of variable speed playback, even if a plurality of tracks are played back, a screen similar to that shown in (b) will be played back. That is, a normal screen can be obtained by the same processing in both normal playback and variable speed playback.

Furthermore, even if the envelope of the VTR's RF playback signal is as shown in Figure 11, points 0 and 8 correspond to the top and bottom edges of the screen, so there will be no discontinuities in the screen like in the segment method. .

Furthermore, when a pattern recorded in this manner is reproduced, even if one of the two heads that are simultaneously reproduced becomes clogged, both color signals of cw, . . . and an are reproduced. Therefore, it is possible to prevent fatal damage from appearing on the screen by the playback signal dropout process. Further, since similar luminance and color signals are recorded in adjacent tracks of the same segment, there is little influence from crosstalk.

A second embodiment of the present invention will be described using FIG. 6. Second
The embodiment has 1125 scanning lines as in the first embodiment,
In order to record a signal with a field frequency of 60 Hz (2:1 interlace) and a bandwidth approximately four times that of NTSC, the time axis is expanded and divided into two channels. is recorded as 5ol(z).

FIG. 5 shows segment division in this case.

In this case, since the number of segments is even, the order in which the luminance signals are allocated is set to 1. Second. Second. It is in the order of the first segment. In this case as well, the same effects as in the first embodiment can be obtained.

Next, a third embodiment is shown in FIG. This is the same condition as in the first embodiment, but the combination of the color signal and the luminance signal is changed, and the line number of the luminance signal and the line number of the color signal are made the same to simplify control. Even in this case, the effect of the crosstalk between adjacent color signals of the same segment becomes large, but in the first case. The same effects as in the second embodiment can be obtained.

Effects of the Invention As described above, according to the present invention, the helical scan V
In TR, a video signal in which a color signal is time-axis multiplexed with a luminance signal is divided into two channels, two tracks are simultaneously recorded in one scan, and one field is recorded in sequential N scans using simple processing. Variable speed playback may be possible.

[Brief explanation of the drawing]

1(Δ) is a recording track pattern diagram of the first embodiment method of the present invention, FIG. 1(b) is a correspondence diagram of tracks and scanning lines, FIG. 1(0) is a top view of the rotating drum, The figure shows a TC in which the color line sequential signal recorded by the present invention is time-axis multiplexed to the luminance signal.
An explanatory diagram showing the I signal, Fig. 3 shows the TCI signal in Fig. 2
Explanatory diagram of the process of dividing into channels, Figure 4 (2L)
, (b) is a screen diagram of a signal reproduced from a tape recorded by the method of the first embodiment, FIG. 5 is an explanatory diagram of segment division in the method of the second embodiment of the present invention, and FIG. Third
FIG. 7 is a top view of a rotating drum of a conventional two-head helical scan VTR, and FIG. 8e) is a diagram of a conventional two-head helical scan VTR.
Figure 9 (b) is a screen diagram showing the scanning method; Figure 9 (2L) is a recording track pattern diagram of the conventional segment recording method; (in the figure) is a screen diagram showing the scanning method. , Fig. 10 (2L) is a recording track pattern diagram for explaining variable speed playback in the case of the conventional segment recording method, Fig. 10 (1)) is a correspondence diagram of tracks and screens, and Fig. 10 (C) is a reproduction diagram. The screen diagram and FIG. 11 are waveform diagrams showing the shape of the envelope of the RF reproduction signal of the VTR. 1...Magnetic tape, 2, 2', 3, 3
'・・・Head, 4...Rotating drum, 6
...Record track. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure (Q) ←-Tape running? Thea... f:! , 2 4f 44 El! g
g\,1/\,ノ\,I\1. No +
+++ ζ2,2 ward 6 Kiyoshi 5 Jump Hu 1st figure ward Shoupi OJ. Figure 4 CQ) tb) Total stomach = ni p ward ---. no gun 8 3 ≧ ≧ O -ノ \ノ' () V -ノ
War ~ bolt size ■
-ω 5 ri φ ri Fig. 7 Fig. 8 (α) (b) Fig. 9 CQ) (b Fig. 11 c)

Claims (1)

[Claims] From a video signal consisting of a luminance signal, first and second color signals, the first and second color signals are line-sequentialized, time-axis compressed, and time-axis multiplexed on the luminance signal, and the time is approximately doubled. When the axis is expanded and divided into two channels, and two tracks are simultaneously recorded and one field is sequentially recorded by N scans, the first color signal and the second color signal are applied to both of the two tracks. The scanning lines are recorded at approximately equal intervals, and the scanning lines from the beginning of the screen to the end of the screen are sequentially recorded on all 2N tracks constituting one field, continuously from the scanning start position to the scanning end position on the track. A video signal recording method characterized by: