A drive Method for a Direct-drive Motor Built into a Camcorder Lens Barrel

摘要

Camcorders would be more compact, lighter, andlower-priced if their drive motors were built into their lensbarrels. We propose a new direct-drive motor built into a lensbarrel. This motor has a three-phase set of armature windings.Only two phases are excited by a rectangular source, and theother phase is not excited. This paper presents a new drivemethod, called "three-phase on mode by a sinusoidal source," inwhich all three phases are excited by a sinusoidal source to get asmooth axial shift of a rotor. We confirmed that the rotor of themotor shifted smoothly in an axial direction, using the new drivemethod. Calculated rotor displacements and times agree wellwith measured values. Torques do not depend on frequency andare constant below 20 Hz. The principles for the new drivemethod for the motor were verified.