Pf Motor Driver Circuit - Epson Stylus COLOR 760 Service Manual

EPSON Stylus COLOR 760

2.2.2.4 PF Motor Driver Circuit

TheStylus COLOR 760 is equipped with a DC motor for the PF motor. In
addition to the CPU and ASIC, a slave CPU is mounted on the C298MAIN
board. Since the slave CPU is exclusively used to control DC motors, it
reduces duty of CPU and ASIC to offer faster data processing. The block
diagram for the PF motor driver circuit is as shown below:
Figure 2-23. PF Motor Driver Circuit Block Diagram
IC15 slave CPU controls paper feeding amount by referring to the encoder
pulses sent from IC8 ASIC. It also sets a proper drive current value according
to the paper feeding amount and direction. So it outputs specified control signal
to the motor driver. The motor driver IC19 outputs PF motor drive current to the
PF motor according to the control signals from the IC15 slave CPU.
Operating Principles
Unlike a stepping motor, the DC motor that drives the PF motor can not detect
a paper feeding amount by referring to the pulses given. For this reason, a loop
scale is attached on the Gear 76 to mechanically detect a paper feeding
amount.
The loop scale encoder sensor outputs 2two kinds of TTL level pulses Phase A
and Phase B to IC8 ASIC.
Rotational direction of the PF motor is determined by the phase between the
output waveforms of Phase A and Phase B. Refer to Figure 2-24 for different
phase for each direction.
NOTE: If the drive voltage for the PF motor reaches 1A, a fatal error occurs.
Electrical Circuit Operating Principles
1/1440 inches
1/5760 inches
Figure 2-24. Loop Scale Encoder Pulse
Revision C
PF motor CW rotation
PF motor CCW rotation
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