Cut Sheet Pick Up Motor Encoder (Pme - Printronix L5000 Series Maintenance Manual

Cut sheet pickup motor encoder (PME)
This is a rotary encoder, comprised of a slotted plate attached to the cut–sheet pick up
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 revolutions of the cut–sheet pick up motor that carries
out the paper need not be extremely precise. Therefore, a PWM (Pulse width
Modulation) circuit is used to control the average voltage to the motor, which adjusts
the motor on time at a certain operating cycle, via a chopper circuit. The pulse string
that is detected here is fed back to this PWM circuit.
Optional Cut Sheet Feeder D–15