Detectors - Star Micronics LC-1011C Technical Manual

4-2. Detectors

(1) Print head temperature detectors
The A/D converter in the CPU detects the print head temperature at power on and before each line begins to print.
Control Method (by Text printing)
Print
Error stop (thermistor open)
Normal print
Unidirectional print
Print stop
(2) Home Position Detector
A photo-interrupter is used in the home detector on the printer.
ON/OFF signals are generated according to the position of the carriage. (Shield plate mounted at the base of the
carriage.) The printing position is determined by these signals.
V
ref
AN0
CPU
Fig. 2-5 Printer head temperature detector circuit
A/D Conversion Value
POINT
0-5
6-215
216-225
226-251
Detecting
signal
+5V
Fig. 2-6 Carriage home position detector circuit
Output (V)
5 in home position (with shield plate)
0 not in home position (without shield plate)
+5V +5V
Printer head
Thermistor
R1
C1 R2
AN Voltage
V
0.00
0.00-4.22
4.22-4.42
4.42-5.00
+5V
R1
R2
C1
R3
Decision
– 23 –
THEORY OF OPERATION
Temperature
C
-
~120
120-135
Over 135