JPH0682444B2 - Video and PCM audio double speed playback device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a double speed reproducing apparatus for video signals and PCM audio signals.

[Outline of Invention]

Using four rotating heads, a pair of rotating heads with the same azimuth at 180 ° intervals reproduces every other video track, and the PCM audio signal recorded at one end of each video track rotates the remaining pair of reverse azimuths. The head enables reproduction in tracks between reproduced video tracks to enable quick reproduction with audio in which the time axes of video signals and PCM audio signals are doubled.

[Conventional technology]

With a two-turn head VTR called 8mm VTR, the tape winding angle to the drum is 180 ° or more (for example 220 °),
It is known to record a video signal (180 °) and a time-compressed PCM audio signal (36 °) in a time division manner. FM audio signals can be additionally recorded in the video area.
The recording time can be switched to LP (long time) audio SP (short time). As shown in FIG. 4, since the tracks are closely arranged in the LP mode, opposite azimuths are attached to both heads to reduce crosstalk by the azimuth effect.

[Problems to be solved by the invention]

When fast-forwarding playback is performed by doubling the tape running speed, as shown in Fig. 4, even if the head can read and scan with the correct azimuth in the video section, the reverse azimuth section of the adjacent track in the audio PCM section at the beginning of the track However, it was difficult to reproduce. The FM audio signal superimposed on the video section can be played at double speed,
In this case, it will be monaural.

An object of the present invention is to solve this problem so that a PCM audio signal can be reproduced during fast-forward reproduction.

[Means for solving problems]

This is a reproducing device capable of alternately recording a video signal with a rotary head of reverse azimuth and reproducing a recording medium having a PCM audio signal recorded at one end of each video track at double speed.

As shown in FIG. 1, a pair of first rotary heads Sa and Lb arranged in close proximity to each other and having a reverse azimuth relationship, and
The pair of rotating heads is composed of a second pair of rotating heads Sb and La of opposite azimuths which are provided at an angle difference of about 180 ° with respect to the pair of rotating heads.

During double speed reproduction, a pair of rotary heads (for example, Sa, La) of the same azimuth at 180 ° intervals of the first and second rotary head pairs are alternately used to reproduce a video signal in every other track. However, the PCM audio signal is reproduced by alternately using the remaining pair of rotary heads (Lb, Sb) at one end of each track between the reproduction video tracks placed every other line.

〔Example〕

FIG. 1 is a block diagram of an 8 mm VTR reproducing system to which an embodiment of the present invention is applied. The rotating drum 1 has about 220 magnetic tapes.
It is wound in an angle range of °, the 180 ° section is assigned to the video section, and the 36 section is assigned to the PCM audio signal section. Therefore, as shown in Fig. 4, a PC is placed at the beginning of the track.
The M signal is recorded, followed by the video signal.

A set of 180 degree magnetic heads Sa and Sb are for high image quality
A wide head with a wide track width for recording and replaying in P mode (short time). The other pair of magnetic heads La and Lb at 180 ° intervals are for standard image quality, and are narrow heads with a narrow track width for recording and reproducing in LP mode (long time). Heads Sa and Sb, La and Lb are mutually opposite azimuths, Sa and L
Each of b, Sb and La is composed of an integrated double azimuth head.

The reproduction output of each head is led to a video channel and a PCM channel via the S head and L head changeover switches 3a and 3b and the a channel and b channel changeover switches 4a and 4b. The video signal is processed by the video reproduction circuit 5, and the PCM audio signal is demodulated by the demodulation circuit 6 and then written in the memory 7 and encoded.
It is time-expanded, read by the D / A converter 8 and converted into an analog audio signal.

During normal playback, the selector switches 3a and 3b are set to the S side (or L
The video signal and the audio signal are derived by switching the signals of the a channel and the b channel by the changeover switches 4a and 4b.

FIG. 2 is a time chart during double speed reproduction, and FIG. 3 shows a head scanning locus on a track. In this reproducing mode, for example, only the track Ta of channel a is scanned every other track as shown in FIG. Therefore, for the video signal, the heads Sa and La are alternately switched and used. The tracking servo works so that the head scans approximately the center of the video section. Therefore, in the PCM section at the beginning of the scanning of each head, the track of the b channel having the reverse azimuth is scanned, so that the heads Sb and Lb are scanned.
And are used by switching.

FIG. 2B shows a switching pulse S1 for switching the changeover switches 4a and 4b.
And C indicates a switching pulse S2 for switching the changeover switches 3a and 3b. Switching pulses S1 and S2 are
Each time the video section of ° is scanned, the level becomes high / low alternately. Regarding the video channel, since the a / b channel is selected by the changeover switch 4a and the heads Sb and La are alternately selected by the changeover switches 3a and 3b, as shown in FIG. Is reproduced to the video reproducing circuit 5.

Regarding the PCM audio channel, when the head Sa is selected in the video system, the output of the head Sb is selected by the changeover switches 3b and 4b (the upper contacts respectively). Therefore, the head Sb moves to the third position near the end of the track Ta.
When it extends to the PCM section at the start end of the adjacent track Tb as shown by the dotted line in the figure, the head Sb scans this PCM section and derives it as a reproduced PCM signal.

Similarly, when the head La is selected in the video system, the output of the head Lb is selected by the changeover switches 3a and 4b (contacts on the lower side, respectively). Therefore, at the start end of the next track Ta, the head Lb scans the PCM section of the adjacent track Tb and derives the reproduced PCM signal.

Although the reproduced PCM signal is lost every other track, the time axis is stretched when the memory 7 is read out to form a continuous audio signal, and although it is somewhat unnatural, the recorded content can be sufficiently discriminated.

In FIG. 2C, the switching pulse S2 may be narrowed as shown by the dotted line.

〔The invention's effect〕

As described above, the present invention scans every other video track and reproduces at double speed, and at one end of each track.
For the PCM audio signal, one end of the track between them can be scanned and reproduced by the head of reverse azimuth, so that not only the video signal but also the audio signal can be reproduced at double speed fast-forward.

[Brief description of drawings]

FIG. 1 is a block diagram of an 8 mm VTR reproducing system to which the present invention is applied,
FIG. 2 is a reproduction time chart, FIG. 3 is a diagram showing a track recording pattern and a head scanning locus at the time of double speed reproduction,
FIG. 4 is a diagram showing a track recording pattern and a head scanning locus during conventional double speed reproduction. In the reference numerals used in the drawings, 1 ... rotating drum 2 ... magnetic tape 3a, 3b ... changeover switch 4a, 4b ... changeover switch 5 ... video reproduction circuit 6 ... demodulation circuit 7 ... memory 8 ... It is a D / A converter.

Claims (1)

[Claims] 1. A reverse azimuth rotary head alternately records video signals, and a PC is provided at one end of each video track.
A reproducing device for a recording medium on which an M audio signal has been recorded, the first rotary head pair having a reverse azimuth relationship arranged close to each other, and about 180 ° with respect to the first rotary head pair. A second rotary head pair of mutually opposite azimuths provided at an angle difference of 1 and a pair of rotary heads of the same azimuth at 180 ° intervals of the first and second rotary head pairs during double speed reproduction The video playback circuit that plays back the video signal on every other track by alternately using and the remaining pair of rotary heads at one end of the track between the playback video tracks on every other track alternately to play the PCM audio signal. A double-speed playback device for video signals and PCM audio signals, which is provided with a PCM audio playback circuit for playback.