To compensate for the faults of a developing device, using conventional techniques to obtain a stable print quality by improving the peripheral speed ratio of each developing roller to a photosensitive body and the shape factor of toner for use in a developing device, having two developing rollers, in an imaging method which repeatedly forms many images in a high speed recorder of an electrophotographic method, an electrostatic recording method, or the like.
A first developing roller 61, which moves in a direction opposite to the moving direction of a photosensitive body 1, is placed close to the photosensitive body 1 and on the upstream side viewing from the moving direction of the photosensitive body, so as to face the photosensitive body 1, and the peripheral speed ratio of the peripheral speed of the first developing roller 61 to that of the photosensitive body 1 to 0.8 2.0, and a second developing roller 62 which rotates in the same direction as the photosensitive body 1 is placed on the downstream side of the first developing roll, and the peripheral speed ratio of the peripheral speed of the second developing roll 62 to that of the photosensitive body 1 is 1.05 to 2.0, and shape factors SF1 and SF2 of the toner of a two-component developer, essentially consisting of the toner and a magnetic carrier, are 120 to 170 and 110 to 130 respectively.
ISHIKAWA MASAMI
KAWANISHI TSUNEAKI
MITSUYA TERUAKI
OKADA HISAO
ISHII MASAYOSHI
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