Drive unit for video tape recorder - has electronically-commutated DC motor with bearings simultaneously acting as rotary head bearings

摘要

The drive unit, for a video tape recorder, has an electronically-commutated d.c. motor driving the drum that carries the video head. The motor bearings simultaneously act as bearings for the rotating part of the drum. The fixed, stationary part of the drum is flanged to the motor's end-plate. Apart from the electronic commutation, another circuit regulates the head's phase and speed according to a reference signal. Since the drive uses electronic commutation all acoustic and electrical noise from brushes is avoided. The construction also increases the motor's efficiency by avoiding thermal losses to the rotating head.