MAGNETIC VIDEO RECORDING AND REPRODUCING DEVICE
PURPOSE:To eliminate an unstable oscillation state in the start of reproduction and perform the reproduction excellently by providing a means which holds a phase-locked loop circuit at the same frequency as that in a phase-locked state for a specific time after a capstan motor is started. CONSTITUTI...
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Format: | Patent |
Sprache: | eng |
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Zusammenfassung: | PURPOSE:To eliminate an unstable oscillation state in the start of reproduction and perform the reproduction excellently by providing a means which holds a phase-locked loop circuit at the same frequency as that in a phase-locked state for a specific time after a capstan motor is started. CONSTITUTION:A capstan start signal is inputted to a monostable multivibrator 28 simultaneously with the start of reproduction. Then, the vibrator 28 outputs pulses for several seconds until a drum motor and the capstan motor attain to normal rotating speeds. An offset voltage supply circuit 27 is operated for the period of said pulse generation, and consequently a voltage-controlled oscillator VOC23 is supplied with the same voltage that the VOC23 is supplied with while the phase-locked loop circuit PLL1 is locked. Consequently, the same frequency as that in the phase-locked state is obtained to eliminate the unstable oscillation state in the start of the reproduction mode of VTR, starting normal tracking servo operation speedily. |
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