| 摘要 |
PROBLEM TO BE SOLVED: To obtain an image forming apparatus capable of detecting the driven-rotation position of a shaftless electrifying roller composed of hollow elastic material. SOLUTION: The image forming apparatus is equipped with an electrifying device including an electrifying roller 4 composed of the hollow elastic material and including no rotary supporting shaft. The electrifying roller 4 comes in contact with a surface of a photoreceptor drum 2 and rotates driven by the rotation of the photoreceptor drum 2. A regulating member for deciding the driven-rotation position of the electrifying roller 4 and also supplying the power to the electrifying roller 4 has a larger space than the free shape of the electrifying roller 4, and has a regulating surface regulating the electrifying roller 4 when the electrifying roller 4 is driven-rotated. In order to detect the driven-rotation position of the electrifying roller 4, hole parts 4a and 4b passing through the electrifying roller in a direction perpendicular to the axial direction of the roller are formed in one end part of the electrifying roller 4, and also, a light emitting element 21 and a light receiving element 22 are disposed, and the driven-rotation position of the electrifying roller 4 is determined based on a time required for the light to pass through the hole parts 4a and 4b. COPYRIGHT: (C)2010,JPO&INPIT |
