JPS5740278A - Developing method in electrophotography - Google Patents

Abstract

PURPOSE:To form optionally an erecting image and an inverted image having good quality with a simple constitution, by executing a development treatment by use of, for instance, two development rolls, to which prescribed bias voltage have been applied, respectively. CONSTITUTION:When prescribed bias voltage is applied to the first development roll 5 formed by a sleeve 6 and a magnet roll 7, an electrically conductive toner on the sleeve 6 is charged to the same polarity as the bias voltage. Subsequently, the toner adheres onto an unexposed part which is charged with the charge whose polarity is different from that of the toner of a photoreceptor 1 whose electrically conductive substrate 4 is grounded, and on the exposure part, the adhering quantity of a toner is decreased due to neutralization, and a picture having fog is formed on the photoreceptor 1. Subsequently, when bias voltage to be applied to the second development roll 9 constituted in the same way as the roll 5 is made smaller than the bias voltage of the roll 5, a toner on the unexposed part is magnetically absorbed by the roll 7, the toner adheres to the exposure part, and the last picture becomes an inverted image having a good quality. When this bias voltage is made almost same as the bias voltage of the roll 5, a correct having an erecting image quality is formed in the same way.