| 摘要 |
PURPOSE:To prevent a photosensitive object unit from breaking off by setting the twisting direction of the thread of a spiral gear so that the synthesized thrust of a plurality of driven gear may be generated in the engaging direction of the photosensitive object unit. CONSTITUTION:A drum driving gear 51 and a drum driven gear 15, a cleaner driving gear 52 and a cleaner driven gear 47 are composed of spiral gears and the twisting direction of the thread of drum driven gear 15 is set in left-side down state, and the twisting direction of the thread of the cleaner driven gear 47 is set in right-side down state to make them mesh each other. Therefore, when the drum driving gear 51 and the cleaner driving gear 52 are rotated, thrust forces Fa1, Fa2 in the engaging direction of a photosensitive object unit 1 are generated in the drum driven gear 15 and the cleaner driven gear 47. Accordingly, as thrust forces are always exerted on the photosensitive object unit 1 to press it in the apparatus main body, the photosensitive object unit 1 is pressed back so that its breaking off can be prevented. |
