3- 2．Sensor - SANEI ELECTRIC SK1-21A Technical Manual

3- 2．Sensor
(1) Paper-end sensor
The paper-end sensor is installed into the paper path and the photo-interrupter detects the
existence of paper in the printer. When the paper runs out, the red LED lights and the printer
goes into error mode and stops in the printing process.
After the paper is replaced, the printer resumes printing.
・Once the paper end sensor sends the paper empty signal, the printer stops printing.
・As soon as the paper end strip appears, replace the paper roll.
(2) Head open sensor
The head open sensor detects whether the print head is open or closed. Once the sensor detects
the head open signal, the printer stops printing and goes OFF-Line, the Error LED lights Red. The
printer resumes printing after the head is closed.
(3) Thermistor
The thermistor built in the print head detects the temperature of the print head.
If printing at a high printing rate for a long time, the print head temperature rises and
the head may become overheated. To prevent overheating, the printer stops printing when the
temperature is beyond a certain level, and blinks the red Error LED.
SK1-21A/31A
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