Printer Control - Sharp XE-A302 Service Manual

3. PRINTER CONTROL

3-1. STEPPING MOTOR CONTROL
The two phase Bi-Polar stepping motor is driven at a constant voltage
by SANYO LB1838M.
1step: 0.087mm, 1dot: 2step
< CPU's PORT >
No. CPU PORT Signal to be used
76 P14
75 P15
74 P16
73 P17
< Driving steps >
Driver IC input
(CPU output)
STEP IN1 IN2 ENA1 ENA2
1 L L H
2 H L H
3 H H H
4 L H H
*When the motor is at rest, the same phase as the final excitation
phase is RUSH energize to turn off all phases. 3 Turn ENA1 and
ENA2 into L.
No energizing should be allowed at lease 40 ms after stopping the
motor before restarting.
When starting the motor etc, required the chopping
3-2. HEAD CONTROL
HEAD: 288 dots in all, width: 0.167mm/dot (6dot/mm)
<Related PORT>
No. I/O PORT Function
18 OUT P84
89 OUT P107
30 OUT P70 TXD2
28 OUT P72 CLK2
90 OUT P106
91 OUT P105
/STB1: 1 ~ 144 dot: 144 dots in all
/STB2: 145 ~ 288 dot: 144 dots in all
1
IN1
IN2
ENA1
ENA2
Motor driving signal
A B /A
(OUT1) (OUT3) (OUT2) (OUT4)
H H H L
H L H H
H L L H
H H L L
Port setup
Signal Initial
in single
name value
chip mode
PRINTING
H
Out L
/STB2
PRINTING
H
Out L
/STB1
PRINTING
DAT H
Out L
(Print DATA)
PRINTING
PCLK
Out L
(Transfer Clock)
PRINTING
/LAT H
Out L
(DATA Latch)
PRINTING
VPON (Head
L
Out L
motor POWER
SUPPLY)
Total 288 dots
288
XE-A302U HARDWARE DESCRIPTION
Conduction pulse width: Refer to the M-T53II specifications.
OFF time of print strobe
Logo print ratio restriction : Average print ratio 35% or below (Same as
*When turning on or off the printer power supply, make sure to turn
/STB1, 2 to "H".
*Do not turn on without paper.
*THERMAL HEAD power supply control : Turns ON when P105= "H";
turns OFF when "L". (The power supply for HEAD and STEPPING
/B
MOTOR is shared). When printing is finished (when the motor is
stopped) Athe power should be turned OFF.
L
*Before printing or feeding paper, perform A/D conversion in 20 ms
L
after the printer head is turned ON and make sure the voltage is sta-
H
ble.
H
(The power supply of the printer head should be turned ON and OFF
by using the regulator IC.)
*The head rank confirmation was abolished.
3-3. WINDING MOTOR CONTROL
<Related port>
No. I/O PORT Function
21 Out P81
3-4. PAPER EMPTY DETECTION
When LOW is detected twice continuously in sampling of signals for
every one dot line, it is judged as paper empty.
The threshold level of High/Low level is 2.5 m 0.2V. (Vcc = 5VDC m 5%)
When paper empty is detected, printing is terminated. However, when
paper empty is detected during printing, 15-dot lines from detection of
paper empty can be printed.
3-5. PLATEN OVER
When signals are sampled in the frequency of 1ms or less and open
state is detected twice continuously, it is judged as platen over.
If the head is conducted under the platen over state, the thermal head
life may be shortened. When, therefore, platen over is detected, printing
is terminated.
Under the platen over state (switch open state), driving the paper feed
motor is inhibited.
– 6 –
: Conduction strobe OFF time between dots
min. 160us
the M-T51)
When the print ratio at the peak one-dot
line is 50%, the average print ratio of 10-
dot line including the above line should be
35% or less.
Signal
Initial Port setup in
value single chip mode
name
Printer motor L
(Winding motor)
ON