| 摘要 |
PURPOSE:To enhance stability by setting a feedback gain to a low value until a phase difference from a reference phase of a phase signal falls within a predetermined range. CONSTITUTION:A drum motor 1 of a VTR is driven by a motor driver 2, and a rotary head drum 3 is rotated at a predetermined speed and phase. This speed is supplied to a speed error detector 4 as a FG signal, and to a phase error detector 5 as a PG pulse. A gain control unit 6 is provided, its feedback gain is set to a low value until the phase difference from the reference phase of the PG pulse falls within a predetermined range, and set to a high value when it falls within it. |
