| 摘要 |
PURPOSE:To prevent deterioration of contrast of latent image potential in the early stage of copying cycles in continuous repeated copying, by using a substance colored in a normal state but decolored by applying light or heat. CONSTITUTION:A substance A colored in a normal state, but decolored by heat or light is applied onto the outer circumference of an exposure halogen lamp 1, and on a reflective cover 3 or on a dust-preventing glass 4. It is rapidly decolored in a first few cycles of copying, and it takes a few hours to return to the initial color. Exposure is small in the first copying cycle, and it increases gradually. Such exposure control permits the potential contrast of a latent image to be retained constant through the initial stage, the first half stage and the second half stage. As the heat-decolorizing substance, copper sulfate, silica gel, iron sulfate are embodied, and as the light-decolorizing substance, a proper substance may be selected from a photochromic substance. |
