| 摘要 |
PROBLEM TO BE SOLVED: To provide a developing device capable of stably obtaining a high- quality printed image excellent in density and uniformity by forming a uniform developer thin layer neither too much nor too little on a developing roll while restraining the deterioration of developer. SOLUTION: This device is provided with the developing roll 21 arranged to be opposed to a photoreceptor drum and developing an electrostatic latent image with toner, and a layer forming roll 23 forming a developer layer on the roll 21 before it is opposed to the photoreceptor drum; the roll 21 has plural magnetic poles nearly equally attracting almost one layer of carrier on its peripheral surface, and the roll 23 is provided to be opposed to the roll 21 through a gap and has an alternating magnetic field generating member 23b generating alternating magnetic field while moving the developer carried on the surface in the same direction as the peripheral surface of the roll 21. In the alternating magnetic field formed by the member 23b, the peak value of magnetic flux density in a perpendicular direction at a position separated from the member 23b by a distance equal to the gap formed between the roll 21 and the member 23b is set to be smaller than the magnetic flux density peak value in the perpendicular direction of the surface of the roll 21. |
