Star Micronics LC-8521, Technical Manual

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Output (V) Decision
0 Paper present
5 Not paper
(3) Paper end detector (Front)
This detects the paper from the front of the printer. When paper is present, the photo transistor with the reflecting
type photo sensor goes on. As soon as paper runs out, this transistor goes off, outputting a paper empty signal.
V
Ref
AN
CPU
+5V
+5V
R2
C1
R3
Paper
R1
Fig. 2-12 Paper end detector (Front) circuit
(4) Paper end detector (Rear)
A photo-interrupter is used in the paper end detector (rear) on the printer.
ON/OFF signals are generated as the paper end activates the paper detector lever mounted at the frame base.
+5V
R2
R1
C1
R3
+5V
Detecting
signal
Fig. 2-13 Paper end detector (Rear) circuit
(5) Paper end detector (Carriage unit)
The paper end detector is located in the carriage unit. The A/D converter in the CPU detects the presence or absence
of paper.
V
Ref
AN
CPU
+5V
+5V
R2
C1
R3
Paper
R1
Fig. 2-14 Paper end detector (Carriage unit) circuit