JPS57115564A - Two-color copying method - Google Patents

Abstract

PURPOSE:To form two-color image without mixed color easily with a simple method, by using a composite photoreceptor and exposing and developing it with a specific system. CONSTITUTION:Uniform negative charge is applied to a photoreceptor 10 of boss charge property (sensitive to red and blue lights) (primary charge), and after image exposure by optical image of red/black two-color original O is made via a red filter FR, positive polarity charge is made by a charger 1 secondary charge) to give a surface potential of positive polarity proportional to the potential before the secondary charge. The image exposure of the original O is made by a suitable amount via a blue filter FB so that the potential at white part is a mean value between the black and red image potential (e.g., black; 40V, red; 450V and white; 230V). Next, 220V of bias voltage is applied, inverted development is made with a positive charged black toner TN, 240V bias voltage is applied to develop with a negative charged red toner TR, and two-color visual image is transferred on a sheet.