| 摘要 |
<P>PROBLEM TO BE SOLVED: To easily estimate that a jam is caused by a failure of a sensor for sensing passage of paper. <P>SOLUTION: An image forming apparatus includes: a passage detecting sensor (sensor) provided above a conveyance path for conveying recording paper to sense passage of the recording paper; a unit for measuring the number of sheets passed which measures the number of recording paper sheets detected to be passed (the number of sheets passed) for each sensor; a jam detection unit which detects, when a time difference in detection of passage of recording paper between two continuously disposed sensors is larger than a time predetermined according to the combination of the two sensors, occurrence of a jam in a section with the two sensors at both ends (jam occurrence section); and a sensor failure estimation unit which compares, upon detection of the occurrence of a jam, the number of sheets passed corresponding to the upstream and downstream sensors in the jam occurrence section with the number of sheets for failure determination predetermined in conformation thereto, and estimates that a sensor determined to have the number of sheets passed which is larger than the number of sheets for failure determination is failed. <P>COPYRIGHT: (C)2012,JPO&INPIT |
