equal in size to the original, the toner at the side edge of photosensitive member is not transferred to the copying paper, but remains as a whole on the photosensitive member, whereby removal of the attached toner not only largely loads the machine but also produces much dust around the same, and further a large amount of toner is wasted so as to be not economical. For copying paper smaller than the original, the same problem as the above will be created.
In order to solve the above problem, an erase light source has been proposed which dissipates charge on the side edge areas of the photosensitive member at first electrified at the overall surface, the side edge areas being positioned perpendicularly to the moving direction of photosensitive memberand unnecessary for forming the image of original.
Also, a device (disclosed in the U.S. Pat. No. 3,792,913) has been developed which detects the size of copying paper to change corresponding thereto the size of the projection areas of erase light source at the side edges perpendicular to the moving direction of photosensitive member, which dissipates the charge in the area of the photosensitive member not contacted by the copying paper during the transfer, thereby preventing unnecessary toner from attaching to the photosensitive member.
Recently, an electrophotographic copying apparatus has been developed, in which the image of original can be copied in reduction or enlargement via selective variation of the copying magnfication. The image of original, when copied in reduction, is formed on the photosensitive member in reduction by a