Rotary head type magnetic recording and reproducing unit

Claim 2

A rotary head type magnetic recording and reproducing unit, comprising: two pulse generators respectively producing high frequency and low frequency pulse series in synchronism with a rotational phase of a rotary shaft of a rotary magnetic head assembly; a first servo-control loop to control the rotational phase of said rotary shaft during recording so as to provide a predetermined phase difference with respect to the vertical synchronizing signal in a video signal to be recorded through the comparison of the phase of said low frequency pulse series with the vertical synchronizing signal; a second servo-control loop to control the rotational phase of said rotary shaft during recording so as to provide predetermined phase differences with respect to the horizontal synchronizing signal in a video signal to be recorded through the comparison of the phase of said high frequency pulse series with the horizontal synchronizing signal; and a means to switch between said first and second servo-control loops.

Claim 3

A rotary head type magnetic recording and reproducing unit according to claim 1, wherein said means to switch between said first and second servo-control loops is so constructed as to automatically switch from said first over to said second servo-control loop a predetermined time after starting the recording.

Claim 4

A rotary head type magnetic recording and reproducing unit, comprising: two pulse generators respectively producing high frequency and low frequency pulse series in synchronism with a rotational phase of a rotary shaft of a rotary magnetic assembly; a first servo-control loop to control the rotational phase of said rotary shaft during recording so as to provide a predetermined phase difference with respect to the vertical synchronizing signal in a video signal to be recorded through the comparison of the phase of said low frequency pulse series with the vertical synchronizing signal; a second servo-control loop to control the rotational phase of said rotary shaft during recording so as to provide predetermined phase differences with respect to the horizontal synchronizing signal in a video signal to be recorded through the comparison of the phase of said high frequency pulse series with the horizontal synchronizing signal; a switching means to select either one of said firSt and second servo-control loops; wherein outputs from oscillators respectively at the frequencies of the vertical and horizontal synchronizing signals are used as the first and second reference signals during playback of a video signal.

Claim 5

A rotary head type magnetic recording and reproducing unit, comprising: two pulse generators respectively producing high frequency and low frequency pulse series in synchronism with a rotational phase of a rotary shaft of a rotary magnetic assembly; a first servo-control loop to control the rotational phase of said rotary shaft during recording so as to provide a predetermined phase difference with respect to the vertical synchronizing signal in a video signal to be recorded through the comparison of the phase of said low frequency pulse series with the vertical synchronizing signal; a second servo-control loop to control the rotational phase of said rotary shaft during recording so as to provide predetermined phase differences with respect to the horizontal synchronizing signal in a video signal to be recorded through the comparison of the phase of said high frequency pulse series with the horizontal synchronizing signal; a switching means to select either one of said firSt and second servo-control loops; wherein outputs from oscillators respectively at the frequencies of the vertical and horizontal synchronizing signals are used as the first and second reference signals during playback of a video signal.