| 摘要 |
PURPOSE:To automatically detect a misprint and prevent an accident, by providing a photoelectric sensor at a position to which the newest print mark on an ink ribbon is minutely fed immediately upon an impact operation, and discriminating a misprint on the basis of an output from the sensor. CONSTITUTION:A pair of print detecting sensor S4A, S4B capable of detecting the presence or absence of a void in an ink layer on an ink ribbon is provided at a position to which the newest print mark on the ribbon is minutely fed by a onecharacter amount immediately after an impact operation, and detection of a misprint is performed based on an output from the sensor. When light is projected on the ink ribbon 14A from the light emitting element S4A, the light-receiving element S4B detects only those ribbon parts at which the ink is lost, namely, void parts of the ink layer, as indicated by a reference sign 14B. When a misprint such as one indicated by a reference sign 14a is present on the ink ribbon 14A already subjected to the impact operation, the misprint is detected by the light receiving element S4B as a misprint 14b in 14B. |
