Carriage Motor Drive Circuit - Epson SQ-1170 Service Manual

2.3.5 Carriage Motor Drive Circuit

This printer uses a DC motor for the carriage drive. To drive the
array E05A48 monitors the encoder signals and then supplies proper voltage to the motor by turning
the motor power on/off. The gate array can recognize rotational direction of the motor (i.e. moving
direction of the carriage) because there are two encoders attached on the carriage with 90-degree phase
difference. The gate array can thus recognize current position of the carriage with reference to the home
position. In detail, the position counter in the gate array is reset every time the carriage hits the left
frame, and the counter counts up as the carriage moves rightward. (Home position sensor is not used.)
The IC 17 (SLA4391 ) is a DC motor driver. This printer is provided with a case open sensor (interlock
switch). When the printer cover is opened during printing operation, the printer immediately stops
printing and moves the carriage to the capping position to cap the printhead. Also, when the interlock
switch is activated, the interlock resistor is inserted in series into the carriage motor drive circuit to
decrease the motor torque. The purpose of this function is to protect users from possible injury they
may suffer when they open the case and touches the carriage as the carriage is moving toward the
capping position.
CPU
This printer has four different carriage speeds as listed below.
Bus
S T O P ENCB
Figure 2-42. Carriage Motor Drive Circuit
Table 2-7. Carriage Motor Drive Modes
Mode No.
o
6.60 KHz
2 2.40 Khz
0 . 4 8
DC
motor at a constant
4391
Carriage
Dot Density
Speed
180 DPI
360 DPI
I
2-33
speed, the gate
Interlock
Register
I
I
CR MOTOR
I
I
I
, ENA
I
ENCODER