Linear drive for a printing apparatus

摘要

A serial impact printing element is mounted on the slider of a high performance linear stepper motor. The slider moves through the stator-to-stator air gap of the linear motor stator comprising an active stator portion having windings associated therewith and a passive stator portion without windings. In order to achieve high performance of the motor, the slider is relatively short as compared with the stator, and longitudinal flux leakage through and the weight of the slider are minimized by the use of nonmagnetic discontinuities therein. The impact printing element includes a wheel having a plurality of circumferentially spaced character elements which are rotated to the printing position by means of a rotary stepper motor. Since there are no windings on the passive portion of the stator, the character elements of the wheel are able to pass in close proximity to the passive portion thereby allowing the center of gravity of the rotary motor to be low so as to achieve stability of the impact printing element during high speed operation.