Cut Sheet Pickup Motor Encoder (Pme) - Printronix L5535 Maintenance Manual

Appendix B
Control Principles

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.
Paper Supply
Preparation Start
Command
MC
Board
Paper Supply
Preparation Stop
Command
248
PBA-OPTION1
On
Off
PWM Circuit
Rotation Speed
Detection
Motor
Encoder
Duty Cycle
Adjustment