| 摘要 |
PURPOSE:To obtain a picture of high concentration, high density and high sharpness degree by a conductive toner and a high resistance toner, by developing the height of a magnetic brush ear by a magnetic brush within specified size between specified magnetic poles on the magnetic pole of a developing roll. CONSTITUTION:To a non-magnetic sleeve 3, bias voltage being opposite in polarity to a latent image is applied by a bias electric power supply 6, and in a developing area, a magnetic brush of a magnetic toner developes a latent image of a photosensitive body 1. This development is overdevelopment by which a toner has adhered to a picture background part, too. After that, the toner image on the photosensitive body enters under an action of the second developing roll 7, absorbs a toner adhering onto the background part of overdevelopment, scan-bends, and adds the bias of the same polarity as the latent image. Subsequently, height of a magnetic brush ear of the first developing roll 2 and the second developing roll 7 is set to 0.15-0.35 between the magnetic poles of 0.5-1mm. on the magnetic pole, and prescribed bias voltage is applied to each developing roll. |
