JPH0444471B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a video signal recording and reproducing device.

BACKGROUND TECHNOLOGY AND PROBLEMS The following techniques are generally used when recording and reproducing moving image video signals on a rotating magnetic sheet, rotating magnetic disk, etc.

Video signals are recorded and reproduced as spiral magnetic tracks.

The magnetic sheet is rotated at a speed that is an integral multiple of the field frequency, and the magnetic tracks are formed in a plurality of circumferential shapes. At this time, the magnetic head is moved to the adjacent track during the vertical synchronization period.

The magnetic sheet and magnetic track are the same, but a plurality of magnetic heads are used by switching.

However, when using the method (2), it becomes difficult to perform stale reproduction, and at the time of reproduction, a technique for tracking a spiral magnetic track is required. Also, in the method, the vertical synchronization period is
Since it takes about 1.2 msec, there are many mechanical problems. Furthermore, the method requires multiple heads.

OBJECT OF THE INVENTION This invention attempts to eliminate the above-mentioned problems.

Summary of the invention Therefore, in this invention, if the original video signal Sy is shown as shown in FIG. 2A (Tv
is the vertical scanning period and Ts is the vertical synchronization period), and during recording, for example, as shown in FIG. The signal St has a blank period Tb at the beginning of the signal St. This signal St is recorded by the method shown in FIG.

Therefore, in the signal St, since the non-vertical scanning period (Tb + Ts) is long, by moving the magnetic head during this period (Tb + Ts), the magnetic head is moved in the radial direction of the rotating magnetic sheet. In addition, the head access mechanism can be slow and simple. It can also be used for still playback.

Embodiment In FIG. 1, numeral 10 indicates a recording system, and the video signal Sy (A in FIG. 2) is sent from the input terminal 11 to the amplifier 1.
2 to the time axis compression circuit 13.
The time axis is converted to the video signal St shown in Figure B, and this signal St is supplied to the FM modulation circuit 14 to generate an FM signal.
Sf, and this signal Sf passes through the recording amplifier 15,
Furthermore, it is supplied to the magnetic head 2 through the recording side contact R of the recording/reproducing switch 1 .

In this case, although not shown, the rotating magnetic sheet 3 is rotated at a speed that is an integral multiple of the field frequency in synchronization with the signal Sy, and the head 2 is rotated in the radial direction of the sheet 3 during the period (Tb+Ts). It is moved by one track for each revolution of 3. Therefore, the signal Sf is recorded on the sheet 3 as a plurality of circumferential magnetic tracks.

Further, 20 indicates a reproduction system, in which the head 2 reproduces the signal Sf from the sheet 3, and this signal Sf passes through the reproduction side contact P of the switch 1, and further passes through the reproduction amplifier 21 and limiter 22 to the FM demodulation circuit 2.
3, the signal St is demodulated, this signal St is supplied to the time axis expansion circuit 24, where it is converted into the original time axis signal Sm, and this signal Sy is taken out to the output terminal 26 through the amplifier 25.

In this way, according to the present invention, the recording and reproduction of the video signal Sy on the magnetic sheet 3 is performed. In this case, especially according to the present invention, if the time axis is compressed to 1/2, the period (Tb + Ts) is approximately 16 msec, and if the time axis is compressed by 10%,
Since (Tb+Ts) is approximately 5 msec, the head 2 can be moved with sufficient time during this period (Tb+Ts), and therefore a simple low-speed head access mechanism is sufficient. Furthermore, since the track is formed in a circumferential shape, stale reproduction is also possible.

In the above, when the signal Sy is obtained from a video camera, the time axis compression circuit 13 can be omitted by obtaining the signal St from the beginning by changing the synchronization of the video camera. Furthermore, the section corresponding to the period (Tb+Ts) of the sheet 3 can be reduced by changing the rotation frequency or phase of the sheet 3 during recording and reproduction.

Effects of the Invention Since the non-vertical scanning period (Tb + Ts) is becoming longer, by moving the rotating magnetic sheet of the magnetic head in the radial direction during this period (Tb + Ts), the movement of the magnetic head becomes easier and ,
The head access mechanism can also be slow and simple. It can also be used for still playback.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an example of the present invention, and FIG. 2 is a diagram for explaining the same. 10 is a recording system, and 20 is a reproduction system.

Claims (1)

[Scope of Claims] 1. In a video signal recording and reproducing device that records and reproduces video signals by moving a magnetic head in the radial direction of a rotating magnetic sheet, when recording video signals on the rotating magnetic sheet, the input video signal is The time axis of the vertical scanning period is compressed and the time length of the non-vertical scanning period is lengthened, and the magnetic head is moved in the radial direction during this lengthened non-vertical scanning period, and the time axis converted image is A signal is supplied to the magnetic head to form and record a circumferential magnetic track, and when reproducing the video signal recorded on the rotating magnetic sheet in this way, the above-mentioned signal is processed by reverse time axis processing to that during recording. A video signal recording and reproducing device configured to obtain an input video signal.