| 摘要 |
<P>PROBLEM TO BE SOLVED: To inform a user or the like of a suitable replacing period of a filter in an image forming apparatus provided with the filter for collecting dust in air exhausted from the apparatus or sucked into the apparatus. <P>SOLUTION: A sensor 3 for measuring the number of dust pieces in air is arranged on the upstream side of the filter in the exhaust direction, and when the integrated number of dust pieces which is measured by the sensor 3 becomes a prescribed number and more, an information means informs the user of the inspection/replacement of the filter 2. In order to more accurately measure the number of dust pieces in air exhausted or sucked from/into the apparatus, the sensor 3 having a light emitting part 31 and a light receiving part 32 and forming a detection hole 33 on the perpendicular bisector of a straight line connecting the light emitting part 31 and the light receiving part 32 is preferably used. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
