2.3.2.3 Carriage Motor Drive Circuit
The carriage motor drive IC SLA7041MS (IC15) outputs a constant current to drive the carriage
motor for the printer mechanism. Gate array E05A96EA (IC2) decides the motor phase andspeed
and then sends a signal to the carriage motor driver IC (SLA7041MS) using the 4-bit serial
transmissionline .
The first bit indicates the direction of the motor rotation. The other three bits are current duty
data for the motor speed of each printing sequence. SLA7041MS can select the reference voltage
itself based on these three current duty data. Also, it receives these signals by 2 serial
transmission lines for 2 motor’s phases (phase A and phase B). Due to this, the carriage motor
candrive the micro step sequence (min. 1/720 inches).
Four-bit serial data is read by the SLA7041MS motor driver with four clock counts from the
E05A96 (IC2) clock. Each bit is read at the falling edges of these clock pulses. Due to this,
received serial data is placed in the shift register and then shifts the latch register. When the
STROBE pulse becomes active from the E05A96 (IC2), the serial data is moved intothe reference
voltage selection circuit, and the voltage is changed. Therefore, when the printer is in the
constant speed mode, this STROBE pulse becomes inactive. The following table indicates the
currentduty of each carriage motor speed mode.
Table 2-8. Serial Data ContentsMode c b a Vref (typical) +
0000
Vref ×1/3
(Vref = +5 V)
×0%
1001 ×20%
2010 ×40 %
3011 ×55.5%
4100 ×71.4%
5101 ×83%
6110 ×91%
7111 ×100%
NPN Tr
(Q27, 28)
E05A96
(IC2)
28
25
30
29
CRB
CRSTB
CLKA
5
16
2
13
CRA
SLA7041MS
(IC15)
CLKB
STBA
STBB
DATA A
DATA B
6
17
CRVRF
REF A
REF B
CRHLD
RSA
RSB
3
14
9
10
CRCLK
(PB0-PB7)
BE
C
C
A
A
B
B
1
8
11
18
1
2
3
4
+35 V
5
(CN6)
31-38
56
Stylus Pro XL Operating Principles
REV.-A 2-17