| 摘要 |
An electrophotographic copying method for optionally producing a direct (positive) copy or an inverse (negative) copy of an original uses an electrophotographic recording material which has one above another on a conductive layer a first and a second photoconductive layer which are sensitive to radiation of a first and a second optical waveband, respectively. It can optionally be subjected to the following method steps before development, transmission and fixing: a) simultaneous charging and irradiation of the recording material with an image of an original which is generated by radiation in the first optical waveband, followed by uniform exposure by radiation in the second optical waveband, as a result of which the charge retained in the dark zone of the charge image produces a positive charge image, or b) simultaneous charging and irradiation of the recording material with an image of an original which is generated by radiation in the first optical waveband, followed by an inverse charging operation which reduces the surface potential essentially to a zero potential and is followed by uniform exposure in the second optical waveband, as a result of which the charge retained in the bright zone of the charge image produces a negative charge image.
|
