| 摘要 |
PURPOSE:To prevent the breakdown of a printer and to improve the rate of operation thereof by amplifying the output of an optical sensor to a low-level gain for checking it up in a printer wherein a printing position is controlled by a slit disc and the optical sensor. CONSTITUTION:A central processing unit 23 is provided additionally with a function 23a of instructing the suppression of gain, and an output port 24 has a decoder 24a whereby bus-line signals delivered from CPU23 are collected into a gain suppression instruction signal (e). When a power is supplied to an apparatus or a key 22a is subjected to an input operation, the gain suppression instruction (e) is delivered immediately from CPU23 to turn AGC of an amplifier to be at a low level and simultaneously to drive a printing head to conduct one spacing reciprocation. When the output (a) of a light-receiving element 4b detecting the position of the head is lowered by any reasons at this time, the output (b) of the amplifier 5 is lowered, and thereby a dot pulse (c) or a zone pulse (d) is suppressed in the amplification in the range of low gain. This suppression is detected by a counter 26 or 27, and an alarm is given by an alarming lamp 29 via an OR circuit 23. |
