Motor Driver Circuit - Epson STYLUS PHOTO 925 Service Manual

EPSON Stylus Photo 925

2.2.2.2 Motor Driver Circuit

DC motors are used. The ASF/Pump Motor employed for exclusive use with the paper
loading mechanism controls the paper loading system and the pump system.
This printer employs another DC motor for exclusive use with the cutter mechanism, which
is newly added to this printer.
CR MOTOR DRIVER CIRCUIT
Figure 2-19 below shows the outline of the CR motor drive circuit.
ENA
CR Encoder
ENB
(CN10)
CPU (IC11)
E01A27CA
Figure 2-19. CR Motor Driver Circuit
CPU (IC11) controls the carriage position by referring to the pulse issued by the linear
encoder.
This circuit also outputs a special control signal to the motor driver to drive the motor
by setting an optimum current value for determining the carriage position and
direction.
Then the Motor Driver IC (IC13) outputs the CR motor drive current to the CR Motor.
The DC motor to drive the carriage, unlike a stepping motor, can not recognize the
current position by pulse. The linear scale mounted along the carriage travel region
detects the carriage position physically. The linear scale encoder sensor outputs two
types of TTL level pulses (phase A and phase B).
Operating Principles
+42V
CR-A
Motor Driver IC
CR
(IC13)
Motor
CR-B
Electrical Circuit Operating Principles
Phase A
Phase B
Phase A
Phase B
Figure 2-20. Output Waveform from the CR Linear Scale Encoder
The current moving direction of the carriage is detected based on the pulse waveforms
of phase A and phase B, which are shifted from each other. At the same time, the
carriage position is controlled based on the waveform output from phase A of one
fundamental cycle (1 cycle: 1/180 inch). Especially, all the output waveforms (1/720
inch cycle) of the rise and fall edges of phase A and phase B are used to control the
carriage position while the carriage is at the home position for the ink system.
Revision A
CR Motor runs forward
(Rotor rotates clockwise)
CR Motor runs backward
(Rotor rotates
counterclockwise)
Phase A
Phase B
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