Abstract: A transmission type optical sensor, which is disposed in a position facing a label sheet fed by a sheet feeding mechanism. It detects the position of a label according to the output value of the same, and a reflection type optical sensor, which is disposed in a position facing a tag sheet fed by the sheet feeding mechanism detects the position of a tag according to the output value of the same. The apparatus, when the detection timing of the label or the tag deviates from a predetermined tolerance, detects a sheet failure, and at this time, it (when a label sheet is fed) determines whether the output value of the reflection type optical sensor provided as the sensor for detecting the position of the tag is high or low, or (when a tag sheet is fed) determines whether the output value of the transmission type optical sensor provided as the sensor for detecting the position of the label is high or low.

Abstract: A label printer includes a communication interface for sequentially inputting issue label data; a frame memory for storing print pattern data; a printing unit for printing print pattern data stored in the frame memory; and a processing circuit for creating print pattern data corresponding to input issue label data in the frame memory. With the above label printer, the processing circuit determines an empty area of the frame memory which is different from an area occupied by the to-be-printed print pattern data when issue label data is input from the communication interface and creates print pattern data corresponding to input issue label data in the empty area.