Abstract
Camcorders would be more compact, lighter, and lower-priced if their drive motors were built into their lens barrels. We propose a new direct-drive motor built into a lens barrel. This motor has a three-phase set of armature windings. Only two phases are excited by a rectangular source, and the other phase is not excited. This paper presents a new drive method, called “three-phase on mode by a sinusoidal source,” in which all three phases are excited by a sinusoidal source to get a smooth axial shift of a rotor. We confirmed that the rotor of the motor shifted smoothly in an axial direction, using the new drive method. Calculated rotor displacements and times agree well with measured values. Torques do not depend on frequency and are constant below 20 Hz. The principles for the new drive method for the motor were verified.
