Abstract: A cylindrical structure is formed by a cylinder and a terminal engaging member, such as a gear or a flange for rotating the cylinder. The inner surface of the cylinder is processed for a socket joint. The engaging member has a head inserted to the cylinder and a plurality of recesses adjacent to the head, and is fastened to at least one end of the cylinder by bending and cutting the cylinder, at plural parts thereof, into the recesses of the cylinder. The engaging member is preferably equipped with a helical gear. The cylindrical structure is characterized by the joint between the cylinder and the terminal engaging member, which joint can be formed securely in a simple manner and at a high accuracy. The cylindrical structure may be embodied, e.g., as a photosensitive drum or a developing sleeve for electrophotography.

Abstract: A method for forming a cylindrical structure by fastening an engaging member to an open end of a cylinder, including the steps of preparing an inner surface at the open end of the cylinder to provide the cylinder with a reduced thickness, providing an engaging member having a plurality of discrete recesses formed circumferentially around the periphery of the engaging member, and fitting the engaging member into the processed open end of the cylinder. The invention further comprises bending and cutting the processed open end of the cylinder around the open end of the cylinder such that plural projections project into the recesses of the engaging member. In this manner the engaging member is restricted from relative movement between the cylinder and the engaging member in both the longitudinal and rotational directions.

Abstract: A reading optical system comprises a transparent block a part of whose bottom surface is an inclined surface forming an angle with respect to the horizontal plane, combined light-guides embedded in the block and having one end thereof all disposed on the intermediate portion of the inclined surface spaced apart by a predetermined distance from the lower end of the inclined surface and the other end extending on the upper surface of the block, a light sensor installed on the upper surface of the block in opposed relationship with the other end of the combined light-guides, and an illuminating system for illuminating the vicinity of the surface of an original opposed to the one end of the combined light-guides, through the block.

Abstract: A luminance amplifier comprises excitative irradiation generating device for exciting a fluorescent body which extends continuously or discontinuously, a plate carrying said fluorecent body and a grating disposed intimately close to said plate and including a plurality of minute cells which are provided with light-diffusive walls. The minute cells are adapted to amplify the luminance in the irradiant area on the fluorescent body which is excited by the excitative irradiation.