Patent ID: 8768224

Claim:
A developing device comprising: a first developer carrying means for performing a first developing process of developing a latent image on a latent image carrying means with a developer containing toner and carrier particles, the developer being carried on a surface of the first developer carrying means that is moved in a same direction as a moving direction of the latent image carrier at a faster linear speed than the latent image carrying means at a first developing region facing the latent image carrying means; a second developer carrying means for performing a second developing process of further developing a toner image obtained by the first developing process with a developer carried on a surface of the second developer carrying means that is moved in a same direction as a moving direction of the image carrier at a faster linear speed than the latent image carrier at a second developing region facing the latent image carrying means; and a bias output means for outputting a developing bias to be applied to the second developer carrying means, the developing bias including a direct-current component and a non-rectangular alternating-current component whose waveform has an edge at which a direction of an electric field between the second developer carrying means and a background portion of the latent image carrying means is changed to a direction in which the toner is moved from the background portion toward the second developer carrying means, the edge of the waveform having a gradient more gentle than that of a rectangular wave.