JPS5570857A - Four-color electrophotographic copying method - Google Patents

Abstract

PURPOSE: To form four-color copy image in a simple constitution, by exposing the photosensitive drum on which two photoconductive layers differing in spectral sensitivity with the original image lights through different filters, and developing and processing with coloring toners of different colors.

CONSTITUTION: At the first rotation of a photosensitive drum 1 on which two photoconductive layers differing in spectral sensitivity, red and green visible images are formed on the drum 1 by means of a charger 2 for primarily charging the surface of the drum 1 uniformly, a charger 3 for forming latent image performing secondary charge in the reverse polarity of the charger 2, optical system 4, yellow filter YF for primary exposure, and developing devices 5, 8 for developing with red and green toners in the reverse polarity of the surface potential on the drum 1. At the second rotation of the drum 1, development by using a blue toner by a developing device 6 after secondary exposure by blue filter BF, uniform exposure by green filter GF, and development with black toner by a developing device 9 are performed, and a four-color visible image of the same charge polarity by a precharger 13 is formed on the drum 1, so that four-color image may be copied in a simple constitution.

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