| 摘要 |
An image forming apparatus includes a photosensitive member rotatably supported by a bearing portion provided on a supporting casing; a motor fixed on the supporting casing; a driving gear provided on the supporting casing; and a driven gear for being engaged with the driving gear to be rotated integrally with the photosensitive member. The driven gear includes teeth each of which is crowned such that a tooth thickness is maximum at a maximum tooth thickness position with respect to the gear thickness direction. A maximum force receiving position of the tooth where a force received by the driven gear from said driving gear is maximum when the photosensitive member is driven is different from the maximum tooth thickness position. The tooth thickness decreases from the maximum tooth thickness position toward the maximum force receiving position at a first degree and decreases from the maximum tooth thickness position away from the maximum force receiving position at a second degree, by the crowning. The first degree is larger than the second degree.
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