| 摘要 |
PURPOSE:To accurately decide the time for replacement by detecting the cumulative value of the number of revolutions of an image carrier, thereby calculating the length of the life of the image carrier. CONSTITUTION:A bar code in which a drum identification mark is recorded is stuck to the photosensitive drum 1, outside an image forming area. The information of this bar code is read by a reading driver 21 to be stored in a memory 22. A drum attachment sensor 24 detects the presence or absence of parts which are invariably detached in the replacement of the photosensitive drum 1, for example a drum partition and an inside cover, and generates a drum attachment signal. By means of the drum attachment signal, the drum identification mark is stored in a memory 25. A revolution counter 30 for the photosensitive drum 1 converts the number of revolutions of the photosensitive drum 1 to a pulse and stores it in drum rotation memories 33 and 34 via gates 31 and 32, respectively. In each of the drum revolution memories 33 and 34 the prescribed number of revolutions is set. When the cumulative count value of each reaches the prescribed number of revolutions, the indication of the necessity of drum replacement is provided on a display 37. |
