| 摘要 |
<p>PURPOSE:To change over easily the speed to a reproducing speed corresponding to the video recording mode of a tape (at intermittent slow reproduction), by detecting information of reproducing control pulse frequency and phase information of a horizontal synchronizing signal so as to monitor the video recording mode accurately at all times. CONSTITUTION:A horizontal synchronizing signal at intermittent feed is separated at a horizontal synchronizing separation circuit 25, applied to one input terminal of a phase comparator 30 and inputted to a trapezoidal generator 26. A voltage controlled oscillator 28 oscillates a double horizontal frequency, which is inputted to the phase comparator 30 via a 1/2 frequency division circuit 29 to form a sampling pulse of a sample holding circuit 27. The phase comparator 30 generates a detected output when the phase of the horizontal synchronizing signal is changed. A pulse obtained from a pulse detection circuit 31 is change catching information of the recording mode (1hr mode or 2hr mode), and a holding circuit 17 switches the stored recording mode information to either of 1hr mode or the 2hr mode.</p> |
