Cut Sheet Pickup Motor Encoder (Pme) - Printronix L5035 Maintenance Manual

Appendix C
Optional Cut Sheet Feeder

Cut Sheet Pickup Motor Encoder (PME)

The cut sheet pickup motor encoder is a rotary encoder that consists of a
slotted plate attached to the cut sheet pickup motor rotating axis, with a light
emitter and receptor on either side of the plate. The motor rotation is detected
by the pulse string that is created by light passing through the rotating slotted
plate. The rotational speed of the cut sheet pickup motor need not be
extremely precise. Therefore, a PWM (Pulse Width Modulation) circuit is used
to control the average voltage to the motor. This circuit adjusts the duty cycle
of the motor (percentage of the time that the motor is turned on) via a chopper
circuit. The pulse string that is detected here is fed back to this PWM circuit.
MC
board
642
Duty cycle
adjustment