| 摘要 |
A rotational phase detecting apparatus for a head drum utilizing a video head capable of directly detecting the rotational phase of the head drum for the reproducing signal of the video head without using an additional pulse generating head by disposing a permanent magnet facing the rotational direction of video heads. When video heads pass by the permanent magnet, positive pulses are generated from the video heads and the positive pulse signal of the first video head is applied to a phase detecting signal processing unit via a rotary transformer and the positive pulse signal of the second video head is converted into a negative pulse signal at the rotary transformer and applied to a phase detecting signal processing unit.
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