PRINTER ESCAPEMENT CONTROL SYSTEM

摘要

Disclosed is a digital escapement control system in which the motor (DC) control is completely digital requiring no tachometer generation of feed back signal nor any analog to digital convertors. Connected to the DC motor shaft is a code wheel and detector to determine the time between discreet positions of the motor shaft as it rotates. The time between discreet positions is then compared with a desired time, and the difference is stored, as by a register. The difference is then converted to a pulse-width-modulated (PWM) signal which directly controls the rotational velocity of the motor, increasing or decreasing it as necessary. The system operates, in a ramp, open loop start up mode and digital velocity controlled braking mode while in the motional mode with the feed back as described above. At start up, provision is made for inserting the feed back loop when the velocity reaches some predetermined level or percentage of the desired velocity.