| 摘要 |
PURPOSE:To correctly detect fogging on printing paper by providing one or plural detecting element detecting a toner picture on the printing paper, detecting the toner picture on the printing paper before and after exposure is carried out, and comparing the outputs of the detecting elements before and after the exposure. CONSTITUTION:Exposure data for forming the toner picture on the photosensitive drum 11 is stored into a storage element 21 by each dot line. As for a fogging on the printing paper fogging detecting part 23, whether or not each part of the exposure data corresponding to each position of the detecting elements 221, 222, 223 and 224 is 'white', i.e., data for not forming the toner picture on the printing paper is detected by each dot line based on the output of the storage element 21. Then, after the exposure is carried out on the photosensitive drum 11, the toner picture formed thereon is transferred onto the printing paper by a transfer charger 13, and the outputs of the detecting elements 221, 222, 223 and 224 with respect to the toner picture transferred onto the printing paper are detected. When the output corresponding to the exposure data which was 'white' before the photosensitizing is at 'L' level (a picture is detected), it is judged that the fogging arises on the printing paper. |
