Serial printer capable of promptly detecting abnormality in head carriage movement

摘要

A movement distance monitoring pulse counter counts drive pulses being applied to a carriage-moving pulse motor, and produces a count value M. An optical sensor attached to a head carriage detects slits of a slit encoder passed by the head carriage. A slit counter counts output pulses of the optical sensor, and produces a reset signal every time the count reaches a preset number of output pulses corresponding to a monitoring carriage movement distance. The count value M is reset in response to the reset signal. When the count value M exceeds a preset number of drive pulses corresponding to the monitoring carriage movement distance, an abnormality detection signal is produced.