JPS596517Y2 - Rotating head type magnetic recording/playback device - Google Patents

Description

[Detailed description of the invention] The present invention uses a helical scan type rotary head that sequentially records and replays approximately one field of television signals using a plurality of rotary heads as a recording locus that is inclined with respect to the longitudinal direction of the magnetic tape. The present invention relates to a type magnetic recording and reproducing apparatus (hereinafter referred to as a VTR), and is constructed so that the switching point of the output of the plurality of rotary heads during reproduction is always at a fixed position on the screen.

In conventional VTRs, the rotating head is switched during playback using a detection signal indicating the rotational phase of the rotating head, and when the rotating head reaches a certain rotational phase, the other rotating head is switched. be.

However, according to this structure, the reproduced video signal and the rotational phase of the rotary head are not necessarily in the same phase due to phase fluctuations of the rotary head during recording and reproduction, tracking deviations during reproduction, etc., and it is difficult to switch the head output. The switching point would be slightly different, and this switching point would appear as noise on the screen of the monitor receiver.

The present invention aims to solve this problem, and is designed so that switching is always performed at a position where a predetermined number of horizontal synchronization signals are counted from the vertical synchronization signals in the reproduced video signal.

One embodiment will be described below with reference to the drawings.

In the drawing, 1 is a running magnetic tape, and 2 and 3 are rotary heads provided with an angle index of 180 degrees, similar to a normal VTR. The magnetic tape 1 with a winding angle
is wrapped around.

Reference numeral 4 denotes a switching circuit that selectively selects each output of the two rotary heads 2 and 3, and the output is F as in the conventional case.
After being demodulated by the M demodulator 5, the signal is guided to the television receiver side, and also to a horizontal synchronization signal separation circuit 6 and a vertical synchronization signal separation circuit 7, respectively.

The horizontal synchronization signal separated by the horizontal synchronization signal separation circuit 6 is applied to the counting circuit 8.

This counting circuit 8 is reset by the vertical synchronizing signal from the vertical synchronizing signal separation circuit 7, and sequentially counts the horizontal synchronizing signals applied thereafter, and counts the horizontal synchronizing signals in a predetermined period slightly shorter than one field. The output is set to a high level when the count reaches a number corresponding to the number of horizontal synchronization signals (for example, 258).

A flip-flop 9 is triggered by the rise of the output of the counting circuit 8 to a high level, and the output of the flip-flop 8 drives the switching circuit 4 to switch the outputs of the rotary heads 2 and 3.

That is, since the head is switched by counting horizontal synchronizing signals corresponding to approximately one field period after the vertical synchronizing signal of the reproduced signal, switching can always be performed at a predetermined position of the projected image.

As described above, in the present invention, since the heads are switched based on the vertical synchronization signal of the reproduced signal, stable head switching can be performed regardless of tracking deviation or the like.

[Brief explanation of the drawing]

The drawing is a block diagram showing one embodiment of the present invention. 2, 3...Rotating head, 4...Switching circuit, 6...Horizontal synchronization signal separation circuit, 7
... Vertical synchronization signal separation circuit, 8 ... Counting circuit, 9 ... Flip-flop.

Claims (1)

[Scope of utility model registration request] In a rotary head type magnetic recording and reproducing device in which a plurality of rotary heads sequentially reproduce partially overlapping television signals, and the reproduction output of each rotary head is sequentially switched by a switching circuit to produce a continuous reproduced television signal. ,
It is reset by the vertical synchronization signal in the output television signal of the switching circuit, and outputs the number of horizontal synchronization signals in the output television signal corresponding to the period slightly shorter than one field. A rotary head type magnetic recording/reproducing device configured to drive the switching circuit by the output of the counting circuit generated.