JPS6136283B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video signal recording and reproducing device such as a VTR, and more particularly to a rotary head type video signal recording device that records and reproduces video signals by transporting a recording medium such as a video tape along a rotary head. Regarding a playback device.

Conventionally, in rotary head type video signal recording and reproducing devices such as VTRs, audio signal tracks and image signal tracks are provided at separate locations on the recording medium, and the audio head and video head are made to correspond to each track. The video head consists of a rotating head to increase the relative speed between the recording medium and the head. Therefore, the recording medium transfer speed in such devices is extremely slow (for example, 2 cm/
sec), so the audio signal obtained from the audio track by the audio head cannot be said to be of sufficient quality.

Therefore, in Patent Application No. 53-129379, the present applicant has already proposed a rotary head type video signal recording and reproducing system that makes it possible to record and reproduce high quality audio signals.

In other words, this video signal recording and reproducing method is as follows:
A video signal modulation wave and an audio signal modulation wave are recorded on adjacent tracks among consecutively existing video tracks on a video signal recording medium by at least a pair of rotary heads that rotate together, and the recording is reproduced. has been done.

First, in a conventional two-head helical scan type VTR, a pair of rotary heads A and B that rotate integrally are fixed to a housing H at a distance of 180 degrees with respect to the rotation axis as shown in FIG.
While transporting the video tape T at a speed corresponding to the number of rotations of the rotary head, field signals of continuous video signals are alternately supplied to the rotary heads A and B, so that continuous video signals are continuously displayed on the video tape T as shown in FIG. video tracks. Track A in FIG. 2 corresponds to rotary head A, and track B corresponds to rotary head B. In FIG. During reproduction, signals recorded by similar rotating heads are detected from video tracks A and B, and these signals are combined to reproduce a video signal consisting of continuous field signals.

On the other hand, audio signals are recorded and reproduced on audio track 1 (two channels in this figure) by an audio head. Track 2 records control signals.

FIG. 3 shows a rotary head used in the video signal recording and reproducing system devised by the applicant mentioned above, in which heads A, B, C,
D are provided with a phase difference of 90° from each other. When the video tape T is transported at a relative speed that is, for example, twice that of the conventional device described above while rotating the rotary head at a predetermined rate, tracks A, C, and B as shown in FIG. 4 are formed on the video tape T. ，
D exists, and tracks A, C, B,
D corresponds to heads A, C, B, and D.

Now, if continuous field signals of video signals are alternately supplied to heads A and B, and audio signals are supplied to heads C and D, the video signals will be recorded on tracks A and B, and the audio signals will be recorded on tracks C and D. The signal is recorded. To explain the scanning process of heads A, C, B, and D in more detail, when head A has scanned half of track A, head C starts scanning track C; When head A finishes scanning half of the track, head B starts scanning track B, and when head B finishes scanning half of track B, head C finishes scanning while head B starts scanning track B. D starts scanning track D, and when head B finishes scanning, head D finishes scanning half of track D while head A starts scanning again, and the sequence is repeated as shown in FIG. A track like this is formed on the tape.

In this way, the band of the audio signal recorded on the video track in the conventional method was reduced to 20KHz.
If a dynamic range of about 80 dB is required, an analog-to-digital converter that samples the audio signal at about 50 KHz and quantizes it at 14 bits may be used. The output of this converter is 14 x 50KHz = 700KHz, and a band of about 1.4MHz is required to record and transmit this, even when considering stereo signals.
If the 3MHz band is secured, it is possible to record and reproduce sufficiently good audio signals.

Heads C and D rotate integrally with heads A and B, and the relative speeds with respect to the video tape T are both equal, and video signals are recorded and played back by heads A and B. Therefore, heads C and D record audio signals. It is also easy to play. In other words, a frequency that does not interfere with the carrier wave of the video signal is used as the audio signal carrier wave, and this carrier wave is used by the digitized audio signal as described above.
Perform FM modulation and send the resulting FM modulated waves to heads C and D.
If the signal is supplied to the tape T and sequentially recorded on tracks C and D and then reproduced, an extremely high quality audio signal can be obtained. Since this audio signal is recorded simultaneously with the video signal recorded on tracks A and B, it is possible to obtain reproduced sound synchronized with the image.

The audio signal thus obtained can be complementarily combined with a signal (not limited to an audio signal) recorded on the original audio track to obtain an audio signal of even higher quality.

Furthermore, heads A and B and heads C and D can record and reproduce different video signals.

FIG. 5 shows an example of a reproducing apparatus in the video signal recording and reproducing method described above.

In this figure, high frequency amplifiers 10 and 11 amplify high frequency signals from heads A and B and heads C and D. In this embodiment, the signals detected by heads A and B are normal video signals.
This is an FM modulated wave, and the signal detected by heads C and D is an FM modulated wave by a digitized audio signal or by another video signal.
It is an FM modulated wave. Of course, the signals recorded and reproduced by heads A and B and heads C and D can be combined in the opposite manner. The video signal modulated wave from the high frequency amplifier 10 is demodulated by an ordinary video signal reproduction processing circuit 12 and reproduced by a display device such as a CRT. on the other hand,
The high frequency signal from the high frequency amplifier 11 is supplied to a filter 13 and a filter 14 . Filter 1
The filter 14 has a characteristic of passing only the video signal modulation wave of the supplied high frequency signal.
is designed to have a characteristic of passing only the audio signal modulated wave. As described above, the frequency of the video signal carrier wave and the frequency of the audio signal carrier wave must be made different to avoid interference with each other. The signal passing through the filter 13 or 14 is detected and smoothed by the detection smoothing circuit 15 or 16 and sent to the detection circuit 17 or 1.
8. The detection circuits 17 and 18 are composed of comparators and the like, and output a logic "1" signal when the input voltage exceeds a predetermined level. When the analog switches 19 and 20 receive a logic "1" signal at the trigger terminal T, they turn on and allow the input analog signal to pass. Therefore, when a video signal modulation wave is detected from heads C and D, analog switch 1
9 is turned on, and the video signal modulated wave from the high frequency amplifier is supplied to the video signal reproduction processing circuit 12 for reproduction processing. On the other hand, when an audio signal modulation wave is detected from heads C and D, the analog switch 20
is turned on, and the signal from the high frequency amplifier 11 is
The signal is supplied to the audio processing circuit 21. Audio processing circuit 2
1 demodulates the supplied signal into an audio signal. Since the analog switch 22 is also on, the demodulated audio signal is amplified by the power amplifier 23 and then supplied to the speaker for reproduction.

When an audio signal is detected from the aforementioned audio track head, the audio signal amplifier 24 amplifies it and supplies it to the analog switch 25. Analog switch 25 is turned on by a logic signal from inverter 26 that inverts the logic signal from detector 18, and supplies the audio signal from sound expansion amplifier 24 to power amplifier 23.

As is clear from the above, the present invention provides recording of different video signals or audio signals and video signals on adjacent tracks of consecutively existing video tracks on a recording medium by at least one pair of rotary heads that rotate together. The present invention provides a signal reproducing device suitable for use in the reproducing method.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of a two-head rotary head;
These figures show the arrangement of tracks on a video tape run by the rotary head of FIG. 1, FIG. 3 is a schematic diagram of a two-head rotary head used in the video signal reproducing apparatus of the present invention, and FIG. 5 is a diagram showing the arrangement of tracks on a video tape scanned by the rotating head of FIG. 3 according to the recording method to be used in the video signal reproducing apparatus according to the present invention, and FIG. FIG. Explanation of symbols of main parts, A, B, C, D...Rotating head, T...Video tape, H...Housing, 1
...Audio track, 2...Control track.

Claims (1)

[Claims] 1. A magnetic tape is driven to at least two rotating heads that rotate together in accordance with the rotational speed of the rotating heads, and the magnetic tape is sequentially scanned in a direction oblique to the tape width direction by the rotating heads. A helical scan magnetic tape signal recording and reproducing system that records and reproduces electrical signals through the rotating heads, wherein one of the rotating heads records and reproduces a first electrical signal, and the other one records and reproduces the first electrical signal. recording and reproducing a second electric signal that is electrically independent from the first electric signal; and determining a reproduction processing method for the one electric signal according to an identification signal included in at least one of the first and second electric signals. A magnetic tape signal recording and reproducing method characterized in that it is made to be selective.