Epson Stylus 200 Service Manual page 30

Operating Principles
2.1.1.1 Carriage Motor Driver Circuit
Carriage motor driver IC UDN2917EB (IC8) outputs a constant current to drive the carriage motor.
CPU M3772152BFP (IC2) determines the motor phase and speed, and then sends a signal to the
UDN2917EB carriage motor driver IC (IC8) via a 4-bit signal transmission line. The carriage motor is
controlled by a 2W1-2 phase drive method. The figure below shows the carriage motor driver circuit
block.
Figure 2-2. Carriage Motor Drive Circuit Block Diagram
Motor driver IC UDN2917EB controls the motor stepping direction and drive current with a
combination of six signals supplied from the CPU. PH1 and PH2 signals control the current flow
direction to determine the motor stepping position; and the I10, I11 and I20, I21 signals determine the
drive current supplied to each motor drive coil. Table 2-1 lists the combinations of these signals used
for the 2W1-2 phase drive control.
Table 2-1. Carriage Motor Drive Sequences
Sequence
^
RTP03
^
PH1
0
0
1
0
2
0
3
0
4
1
5
1
6
1
7
1
8
1
9
1
10
1
11
1
12
0
13
0
14
0
15
0
2-2
Phase A
RTP10 RTP11
Current
Duty
I11 I10
0 0
0 0
0 1 –2/3
1 0 –1/3
1 1
1 0 +1/3
0 1 +2/3
0 0
0 0
0 0
0 1 +2/3
1 0 +1/3
1 1
1 0 –1/3
0 1 –2/3
0 0
EPSON Stylus COLOR 200 / EPSON Stylus 200
Phase B
RTP02 RTP12
PH2 I21
–1 0 1
–1 0 1
0 0
0 0
0 0 0
0 0
0 0
+1 0 1
+1 0 1
+1 1 1
1 0
1 0
0 1 0
1 0
1 0
–1 1 1
+
Current
RTP13
Duty
I22 ^
1 0
0 –1/3
1 –2/3
0 –1
0 –1
0 –1
1 –2/3
0 –1/3
1 0
0 +1/3
1 +2/3
0 +1
0 +1
0 +1
1 +2/3
0 +1/3
Rev. A