JPS59111485A - Recorder of video signal - Google Patents

Abstract

PURPOSE:To reproduce all video signals sithout changing tape width at still reproduction in a video signal recorder using one head by compressing a video signal or changing a winding angle so as to increase effectively the video track length. CONSTITUTION:A video signal is applied from a terminal 11 to an A-D converter 13 via an ACC circuit in a recording system 10 of a VTR recording a PCM audio signal and also applied to a clock generator 14 so as to form a clock synchronized with a synchronizing signal and an enable pulse. Only the video signal part of the A-D conversion output is written in the memory 15. As the synchronizing signal added to the video signal read-out, the signal subject to time axis compression is used, and then the compressed data of the synchronizing signal is stored in memories 16, 17 corresponding to an even and an odd field. In the time axis compression recording like this, all the video signals of the tracks are reproduced by the dynamic tracking servo.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a video signal recording device suitable for application to a VTR which records and reproduces video signals using one head.

BACKGROUND TECHNOLOGY AND PROBLEMS For example, as shown in FIG.
A VTR designed to record one field of video signals has a tape pattern as shown in FIG. That is, the video track is formed as one diagonal track, and near the upper end of this track TV there is a chi 7' (2+
In this example there are two audio tracks, T
Al and TA2 are formed.

When playing back stills with such a VTR that plays tape or turns, the scanning locus is as shown by the chain line in Figure 2. Therefore, by dynamic tracking control of the rotary head H to scan the video track TV, it is possible to reproduce the stills. During playback, the tape (2) is stationary at this time, so if the tape running direction is as shown, the track length LSO of the still track Ts is shorter than the track length L■ of the video track TV. . Therefore, the rotating head H is Lv
After scanning by l (= Ls), the rotary head H no longer hits the tape (2) and the video track T
During the latter half of period LV2 shown by diagonal lines in V, the signal is not reproduced, and therefore a part of the signal is missing. 1 rotation -
- When recording with RAD H, a part of the vertical synchronization signal is recorded in the latter half of the video track TV, so a lack of the video signal or a synchronization disorder occurs.

In order to eliminate partial signal loss during still playback, for example, the winding angle (360
°−〇) to make it thicker and set the track length when still by ΔLS
It is only necessary to increase the length of the video track so that the entire length of the video track TV can be played back by dynamic tracking.

However, if the wrapping angle is increased as shown above, the length of the video track TV will also increase by ΔLv, so the audio track T will be extended in the longitudinal direction of the tape (2) as shown in the figure.
A1. If TA2 etc. is formed, part of the video track TV and audio track TAL + T
There is a possibility that part of A2 will overlap, and in such a case, double recording will occur.

Audio trunk TAIITA to eliminate double recording
However, since this audio track 'rAl l 'I'A2 is usually positioned at the very edge of the tape edge, in order to achieve this purpose, the tape width There is no other way than using a wide chi f(2). If you do this, compatibility will not be maintained. Also,
If a tape with a wide width is used, the recording density of the tape will decrease.

A similar problem occurs in the case of segment recording in which one field of video signal is divided into a plurality of tracks and recorded. The example shown in FIG. 3 is a case of two-segment recording, in which the video signal of the first field of one field is recorded in the first half track 11''Vl, and the video signal of the second half field is recorded in the second half track TV2. The signal is recorded.

In this case as well, there is a lack of video transmission in the shaded section. In the case of two-segment recording, a portion of the video signal at the center of the screen is missing, resulting in a noticeable deterioration in image quality.

Therefore, even in the case of the segment recording method, if the wrapping angle is increased as described above in order to prevent signal loss during still reproduction, the above-mentioned problems occur.

Purpose of the Invention Therefore, in the present invention, in a video signal recording device that records video signals using one head, it is possible to reproduce the entire video signal without changing the tape width etc. even during still playback. be.

SUMMARY OF THE INVENTION Therefore, in the present invention, the video track length is effectively increased, and the video signal is cut off near the end of the video track during recording.

Embodiment Next, an example of the present invention applied to a two-segment recording type VTR will be described in detail with reference to FIG. 4 and subsequent figures.

In this embodiment, the video signal is compressed and recorded in order to effectively increase the video track length. The signal compression is determined by taking into account the hit and miss of the rotary head H on the tape (2) at normal playback speed, and
This also differs depending on the number of H lines between video tracks recording the noise field in the first half of each field. In the chive pattern shown in Fig. 4, the track T has a track length of ΔLvo.
Since VB is the signal missing section during still playback,
The compression ratio is selected so that all the video signals of the dedicated field can be recorded on the remaining track TVF (rack length Lvo). According to experiments, it was sufficient to compress the data by more than 10 H in the dedicated field.

If the signal is compressed and recorded in this way, the effective video track length will be extended even if the wrap angle is the same as before, and the dynamic tracking servo during still recording will allow each track TVI to be
All the video signals of the last field recorded on I TV2 can be reproduced by one rotary head H.

Since the video signal is recorded by one rotating head H, the signal is simply compressed and recorded. If so, part of the video signal of the next dedicated field is recorded in the latter track TVH. I end up.

In order to prevent this from happening, the present invention stops supplying the video signal when the recording of the video signal of field A is completed, and starts recording the video signal of the next outer field from the beginning of the next track. so that by this,
Since the second half track TVB is a no-signal section, this track section can record an information signal (for example, a PCJi audio signal) that is related to or completely unrelated to the video signal recorded on the first half track TVF. .

If no information signal is recorded, it is possible to form a new track extending in the longitudinal direction of Q7' (2+) that intersects this track TVB.In addition to audio signals, this new track can also contain various code signals. , other information signals can be recorded.

FIG. 5 shows an example of a VTR in which a PCM audio signal is recorded on the latter track TVB.

The symbol indicates the recording system, and the video signal sI supplied to the terminal 0υ
is supplied to the ACC circuit (A-D converter 03 via 121), and is also supplied to the clock generator ■ to form a clock synchronized with the input synchronization signal, an enable pulse for writing and reading, etc. . The A-D converted video signal SI is supplied to the memory α5, and in this example, only the video signal portion of the composite video signal is convoluted. Reading starts with a predetermined H delay from the writing time (see FIG. 6).

The synchronization signal added to the read video signal is time-base compressed. That is, in this example, only the synchronization signal portion is time-base compressed to obtain a predetermined compression ratio.

Therefore, two F
Memories (161, αη) such as ROM are provided. One memory α6 is used for data conveniently used in odd fields, and the other memory IJQ"nl is used for even fields.

Memo') (Each data from L5+ to η is switched by the switching circuit Q81 and sent to the D-A converter (1
The scratch converts it into an analog signal. Memory 15) ~Q
Read timing and switching circuit 0 for 71
The switching timing of 81 is determined by the clock generator α.
It is controlled by the output along the line.

FIG. 6 is a diagram showing the timing relationship between the video signal for each field compressed on the time axis and the original signal. In the period 1'H, after recording the video signal of field A, the video signal of the next field ■ is started. This is the time it takes to record a signal.

(20) is a circuit for forming the PCM audio signal SA, and this signal SA and the DA-converted video signal SIc after time axis compression are switched by the switching circuit (21), and the signal is shown in FIG. 6B. As shown, the PCM audio signal SA is recorded on the second half track TVB immediately after the recording of the video signal SIC of the field is completed. Cno is a recording/playback selector switch.

(to) indicates the regenerated yarn, and the regenerated video signal SIC is A
- The video signal SIC is supplied to the D converter 01) and the clock generator (3), and the video signal SIC is A-D converted using a clock synchronized with the reproduction synchronization signal, and this is written in the memory mark).

The data to be written is only the video signal portion as in the case of recording. Data read out at a predetermined timing after writing is converted into an analog video signal by a DA converter 0341.

651 is an analog composite synchronization signal generator, and (36) is a burst signal sB generator, which outputs the composite synchronization signal and burst signal with a normal time axis at a predetermined timing. A synthesizer (371) combines the video signal with a video signal and outputs a video signal including a synchronization signal whose time axis has been expanded.

The reproduced PCM audio signal SA is sent to the decoder (,3
8) and is restored to an analog audio signal.

By compressing the time axis of the video signal and recording it in this manner, it is possible to reproduce all of the video signals marked on each track by performing dynamic tracking servo even during still playback. Therefore, the desired still image can be reproduced without increasing the tape width. Even if the video signal is recorded in segments, the entire video signal can be reproduced, so it is possible to reliably avoid significant deterioration in image quality due to lack of the video signal in the center of the screen.

In addition, if multiple horizontal tracks are formed in parallel in the longitudinal direction of the tape (2) instead of making the track TvB in the latter half a no-signal section, these horizontal tracks are the first and last tracks of the track TV. They may be formed separately on the end portion sides. For example, when forming two horizontal tracks,
It is possible to form one horizontal track above and below the track TV.

Incidentally, in the above embodiment, the video track length is effectively extended by compressing the signal, but of course the video track length may be extended by changing the wrap angle itself.

FIG. 7 shows an example of the rotary head device after the winding angle has been changed.

The wrapping angle is from (360°-θ) to (360°-θ')(θ
′〈θ). If the wrapping angle is increased, the video track length will also be increased accordingly. The track TvS extended by changing the wrapping angle is indicated by is in FIG. The figure shows the case where the non-segment recording method is applied, and the track/TvS
is likely to intersect with the audio track TAL + Ta2. Therefore, in this case, the signal supplied to the rotary head H is only the video signal SI of one field, and immediately after the recording of the video signal S of one field is completed. The supply of signal current to the rotating head H is stopped. The signal current is all signal current including the FM carrier signal.

By doing this, all the video signals of one field can be constrained to still status, and the audio track TAL
+ Even if the position of Ta2 is not changed, the audio track TA1. The influence on TA2 can be avoided.

In the embodiment shown in Fig. 8, the wrapping angle is the same as the conventional one, 9.
The signal may also be compressed and recorded.

As described in detail, according to the present invention, the video track length is effectively lengthened, so that even during still playback, the entire video signal of one track can be played back, and stable, high-quality methylated images can be produced. is obtained. After recording the video signal of 1 track, 1 field, or dedicated field, the signal current is cut off or another signal is recorded, so it is possible to prevent second record and also to prevent a decrease in recording density. .

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a rotary head device, FIGS. 2 and 3 are explanatory diagrams of a track pattern used to explain the present invention, FIG. 4 is an explanatory diagram showing an example of a track pattern based on the present invention, and FIG. FIG. 6 is a block diagram showing an example of a recording/reproducing device according to the present invention, FIG. 6 is an explanatory diagram showing a signal compression state,
FIG. 7 is an explanatory diagram of a rotary head device showing another example of the present invention, and FIG. 8 is a diagram of a track putter 7 when this rotary head device is used. (1) is a rotating drum, (2) is a tape, H is a rotating head, TV is a video track, TS is a methyl track, TAL
. Ta2 is an audio track, (rule is a recording system, 00) is a reproduction system.

Claims (1)

[Claims] When recording video signals by helical scanning with a head, the effective track length can be selected to be long by increasing the tape winding angle around the rotating drum or by compressing the signal and recording. A video signal recording device configured to cut off a recording current based on the video signal at an end of a track.