Electrophotographic method for producing black and color separation

Abstract

An electrophotographic method is disclosed for forming a black (or neutral) toner separation image and a color toner separation image from a single original without cross-contamination of black toner in the color separation image and vice versa. The method entails composing an original containing 'false-color' information--other than black or neutral--corresponding to the black separation image desired and color information corresponding to the color separation image desired. The false-color and color information are selected to absorb actinic light in mutually exclusive wavelength regions of the spectrum. When the original is illuminated, for example, with light having wavelengths in the false-color absorption region only, a light pattern is formed and employed to expose a charged photoreceptor. The resulting electrostatic image is developed with black--or neutral--toner, thereby forming the black separation image. On the other hand, when the original is illuminated with light of wavelengths in the color information region only, the light pattern produced establishes a different charge pattern when used to expose a charged photoreceptor. The latter charge pattern is developed with a colored toner. The black and color toner separation images form a composite image without toner cross-contamination when transferred in register to a receiver.