| 摘要 |
PURPOSE:To generate and output a discrimination signal which uses 4-track scanning period as the period all the time by using a delay circuit which delays control pulses reproduced from a control track by a period longer than a 2-track scanning period and shorter than a 3-track scanning period. CONSTITUTION:A control head 36 reproduces and outputs a pulse (k) which has positive polarity at the leading edge of a recorded pulse (f) and negative polarity at the trailing edge from the control track 9 according to its own differential characteristics. This pulse (k) is supplied to the amplifier 47 in a control discriminating circuit 10, and amplification and waveform shaping are carried out there to perform conversion to a rectangular wave l with a period T0. Then, the rectangular wave is supplied to a monostable multivibrator 8. The monostable multivibrator 48 generates and outputs a pulse whose pulse width is larger than a 2-field period and smaller than the 3-field period. A pulse (m) with the 4-field period is therefore led out of the monostable multivibrator 48. |
