A direct-current electric motor (29) used for, for example, positioning a printing device in an office machine, is controlled by an arrangement comprising a microprocessor (40) which causes the motor digitally to perform accelerations and/or decelerations to maintain it close to a desired speed programmed...http://www.google.com.au/patents/US4605887?utm_source=gb-gplus-sharePatent US4605887 - Arrangement for controlling the speed and positioning of an electric motor
