Originally posted by womble Thanks womble.
Originally posted by the Patent Application: According to the present invention, a rotary actuator is achieved, in which torque in the circumferential direction is produced by magnetic force between the coil body and the multi-polar magnet by controlling currents supplied to the coil body. Accordingly, a reduction gear device becomes unnecessary, and miniaturization and a weight reduction of the actuator become possible. In addition, a high-voltage circuit for driving a motor such as an ultrasonic motor becomes unnecessary. Therefore, in the case where a rotary actuator according to the present invention is used as a drive source for an AF mechanism of a photographic lens, miniaturization of the AF mechanism becomes possible, so that miniaturization and a weight reduction of the photographic lens can be achieved.
So the new motor has more torque so it doesn't need a gearbox. And it can operate at lower voltages so it requires fewer electronic parts.