| 摘要 |
PURPOSE:To form a sharp image by performing reversal development while putting the gap between a developer conveyor which conveys plural-component developers and an image carrier which holds an electrostatic latent image, and the amplitude and frequency of the AC component of a development bias voltage in specific relation. CONSTITUTION:A photosensitive drum 9 is exposed with a recording signal from a data recording part to record an electrostatic latent image. The plural-component developer 31 is contained in the developer reservoir 38 of a developing device 11, and when the developer 31 conveyed onto a sleeve 11A while its thickness is controlled by a napping controlling blade 30 reaches a development area 39, the electrostatic latent image recorded on the drum 9 is developed on reversal basis through the operation of the potential of the drum 9 and electric field by an AC power source 37 and a DC power source 36. Then, an expression is satisfied, where VAC(V) is the amplitude of the voltage of the power source 37, f(Hz) is the frequency, and d(mm.) is the gap between the drum 9 and sleeve 11A. Thus, a sharp image is formed without density deficiency nor fogging. |
