| 摘要 |
PROBLEM TO BE SOLVED: To form an image having high quality without using highly accurate gears by specifying the diameter of the gear of a final stage and circumferential pitches of all gears constituting a gear string. SOLUTION: The diameter of the gear 34 of a final stage is made to be two-times the diameter of an electrophotographic sensitive body (photosensitive drum) 7 of more and also circumferential pitches of all gears constituting a gear sting are set so as to become <=0.8mm. That is, the diameter of the photosensitive drum 7 is, for example, 30mm and the pitch circular diameter of a large, 34 is 60mm and a module (m) is 0.5 and the pitch of one tooth of the gear on an image is made to be 0.78. Generally, the ratio D3/D1 of the pitch circular diameter D3 of the large gear 34 with respect to the diameter D1 of the photosensitive drum 7 is >=2 and (m) is >=0.5 and the pitch (p) of one tooth of the gear on the image is made to be <=0.8. That the circular pitch is <=0.8 on the image means that for example, when the diameter of the drum 7 is 30mm, the circumferential length of the drum becomes 30πmm and at this time, when the number of teeth of the large gear 34 is 100, the pitch on the image becomes 30π/100mm. |
