| 摘要 |
PURPOSE:To prevent the danger caused when a high voltage is applied to a non-high voltage part of a copying device and a driving source of the copying device becomes an endless driving state at the time of runaway of a CPU, by resetting the CPU without requiring person's help even when an abnormal state such as runaway, etc. is generated in the CPU. CONSTITUTION:When a CPU1 is in a normal state, it generates a pulse of a prescribed period as a PLS. In case an abnormality such as a paper jam, etc. is generated, a seven-segment LED display device 6 informs it to an operator by displaying various jam numbers. In case the CPU1 runs away due to the cause of being struck by lightning, etc., the CPU1 generates a longer pulse than a prescribed period, or stops generating a pulse. A watchdog circuit 3 detects a fact that there is no pulse generation in a PLS output, transfers a reset signal to the CPU1 by setting an RST terminal to an ''L'' level, resets it, and also informs to an operator a fact that the CPU1 has run away, by lighting or flickering dots of the seven-segment LED indicator 6. |
