| 摘要 |
PURPOSE:To prevent active substadnce produced through the operation of a charger from corroding an optical element for an electrophotographic copying machine which consists of short-focus, small-diameter image forming elements, by providing a protective layer of an end surface of the optical element. CONSTITUTION:Short-focus, small-diameter image forming elements 1 are stuck with an adhesive 2 and fixed by a frame body 4 to form the optical element 3. An original image O is projected by the optical element 3 on a photosensitive surface I as an erect unmagnification image. This optical element 3 deteriorates in projected image quality unlike an element which uses a large-diameter lens when corroding even partially. For example, if one image forming element 1 is damaged, a copy has a spot omission. For corrosion by ozone, nitrogen oxides produced through the electrolytic dissociation of the corona charger, the protective layer consisting of an organic-solvent soluble type thermoplastic polymer originating from an alkenyl aromatic compound and a polymer with a radical polymerizing unsaturated bond is provided over the end surface of the optical element 3. |
