| 摘要 |
PURPOSE:To prevent contamination which is generated on a white ground part of a copy image by providing a detecting means for detecting the transmission light quantity of a document on a carrying path and correcting automatically density of a copy in accordance with its output. CONSTITUTION:A detecting means 15 is provided on a carrying path of a document D between a document delivery means 23 and a carrying roller 24, etc., and detects the transmission light quantity of the document D. In this state, based on its result, a developing bias voltage of a developing device 3 or the quantity of light of an exposure lamp La is switched so that a bright copy image can be obtained when transmittivity of the document D is high. In such a way, contamination of the back of the document D, and contamination generated in a white ground part of the copy image due to a shadow of a carrying belt 21, the carrying roller 24, etc., can be prevented. |
