| 摘要 |
PURPOSE:To recognize a damage of a part of a heat-generating part by oneself, and to prevent generation of printing failure such as printing unevenness by equipping a diagnostic circuit for detecting trouble of the heat-generating pant by both output signal of a current detection part of the heat-generating part and a driving signal supplied from a main control part to a heat-generating driving part. CONSTITUTION:When a main control part 4 shifts driving signals (L1-Ln) 6 one pulse by one pulse and sends them to the driving circuits Tr1-Trn of a driving part 2 in a time for printing, current is allowed to flow and heat-generating elements R1-Rn are allowed to successively generate heat. When a detection part 3 detects current and a continuous pulselike output signal is sent to the input terminals of one side of AND circuits 8-1-8-n, the driving signals 6 are inputted respectively to the input terminals of the other side of the same circuits. The same circuits send the output signal to the main control part 4 as a detection signal 5. When a part of the elements R1-Rn of a heat-generating part 1 is damaged, a pulse signal is not generated in the correspondent part of the output signal of the detection part 3 and therefore a signal is not outputted from the correspondent circuit. Accordingly the main control part 4 recognizes damage of a part of the heat-generating part 1. |
