| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a drum-jam detecting device capable of surely recognizing the toner image from a photosensitive drum base tube by comparing the signal from a detection sensor having a plurality of different spectral sensitivity in the wavelength range in the spectral reflection factor distribution of the toner to be used with the prescribed reference value for the operation. SOLUTION: A detection member 70 is provided on the downstream side of a transfer electrode in the rotational direction of a photosensitive drum, and is provided with a detection sensor having at least two different spectral sensitivity in the wavelength range in the spectral reflection factor distribution of the toner of one color or a plurality of colors to be used. A microprocessor 510 calculates the drum constant for each light emission source of the detection sensor, and calculates the reference value to recognize the tube level of the photosensitive drum from the drum constant. A comparison circuit 720 compares the signal from the detection sensor with the reference value, and a paper sheet jam judging part judges presence/absence of the paper jam by the operation based on the results of the comparison circuit.</p> |
