Microprocessor-controlled printing mechanism having an opto-electronic sensor

Claim 1

In a printing system incorporating an armature and a driving coil therefore, said armature functioning as a print hammer and a stop for positively locating said armature in its rest position, the combination comprising; an opto-electronic sensor juxtaposed with said armature for developing signals in response to movement of said armature, drive means for supplying an accelerating or decelerating pulse to said armature in response to determination of the time required for said armature to travel over a predetermined distance, control means for receiving plural successive signals generated by said opto-electronic sensor and comparing the time interval between said signals with one of a plurality of stored quantities, said stored quantities comprising a plurality of values corresponding to three separate predetermined intervals of motion of said armature, and a plurality of correction values being stored at locations in memory associated with said stored quantities and corresponding to accelerating or decelerating movement of said armature, means for controlling said drive means for accelerating said armature, during an accelerating interval in accordance with said correction values, means for controlling said drive means for decelerating said armature through a first deceleration interval, and for decelerating said armature through a second deceleration interval immediately prior to the armature returning to said rest position, in accordance with said correction values, said correction values corresponding to exciting current required by said drive means to modify the existing value of armature velocity to a predetermined prescribed velocity.