| 摘要 |
PURPOSE:To achieve prevention of a thermal head from breakage, by establishing a protective circuit for stopping generation of a printing pulse a preliminarily established time later when occurrence of a malfunction in making a power source is detected. CONSTITUTION:When a noise occurs in a signal conductor of output 29 before a trigger 23 is inputted, output 39 of a D type flip-flop(DFF) becomes of a level 'L', and output 41 Y0 of a decoder 40 becomes also of a level 'L'. Further, a load signal 33 inputted to a L terminal of a counter 31 is changed from a level 'L' to a level 'H', and the counter 31 starts to count from 0. When all their outputs Q0-7 become 1, their carry output 32 bocmes of a clock one cycle content level 'H', which is inputted to DFF 34 to be shifted by one clock content, and a pulse 'L' is inputted to an AND circuit 36. The pulse 'L' is inputted to the DFF 38, the output 39 thereof becomes of a level 'H', and the output 41 Y0 of the decorder 40 also becomes of a level 'H'. |
