| 摘要 |
PURPOSE:To reduce running cost and prevent printing quality from being lowered, by detecting the time to replace a regular replacement part the performance of which is lowered with an increase in printing quantity, through counting the printing quantity. CONSTITUTION:A printing quantity counting circuit 8 is provided which receives an output of a light-emitting element 7 as an input, and has an output connected to a microprocessor circuit 2. The element 7 is a laser diode used for development in an electrophotographic printer, and printing quantity is proportional to the light-emitting time thereof. The circuit 8 counts the time for which light is emitted for printing on a paper during the emission of light by the element 7. The counting circuit 8 outputs a signal to the microprocessor circuit 2 when the counted time reaches a predetermined value, then the circuit 8 again counts the light-emitting time, and repeats these operations. Each time the circuit 2 receives the signal, the circuit 2 increments data at an arbitrary address in a nonvolatile RAM circuit 3 by 1. Each address in a ROM circuit 4 corresponds to a periodic replacement part the performance of which is lowered with an increase in the printing quantity, and data at each address is a value representing the replacing period of each part in terms of printing quantity. |
