7.3.8. SUPERVISION CIRCUIT FOR THE THERMAL HEAD TEMPERATURE
1. Function
The thermistor changes the resistor according to the temperature
and uses the thermistor's characteristics. The output of pin 137 of
IC501 becomes a low level. Then when it becomes a high level, it
triggers point A In point C, accordingto the voltage output time,
the thermal head's temperature is detected.
After the thermal head temperature is converted to voltage in B, it
is then changed to digital data in the A/D converter inside IC501.
The CPU decides the strobe width of the thermal head according
to this value. Therefore, this circuitcan keep the thermal head at an
even temperature in order to stabilize the printing density and
prevent the head from being overheated.
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