| 摘要 |
PROBLEM TO BE SOLVED: To improve image quality by transmitting driving force to an electrophotographic photoreceptor drum by using an untwisted projection and an untwisted hole. SOLUTION: A drum flange 16 is a plastic integral molding having a helical gear 16a, a coupling projecting shaft 17, a projecting part 17a and a fitting part, and is a driving force transmitting part having a function for transmitting the driving force. The shape of the projecting part 17a is an almost equilateral triangle pole (which is not twisted) and a recessed part 18a fit to the projecting part 17a is the untwisted hole the cross section of the recessed part space of which is formed to be an almost equilateral triangle. The recessed part 18a integrally rotates with a large gear provided in a device main body 13. In the case a process cartridge B is loaded in the main body 13 and the projecting part 17a is fit to the recessed part 18a provided in the main body 13 so as to transmit the rotational force of the recessed part 18a to the projecting part 17a, the respective ridge lines 17a1 of the almost equilateral triangle pole of the projecting part 17a abut on the almost equilateral triangle internal surface 18a1 of the recessed part 18a. Therefore, their axial centers are nearly aligned with each other.
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