| 摘要 |
An electrophotographic copy of an original is produced by forming on a transparent photosensitive first substrate a latent electrostatic image of the original by contact exposure, applying a toner powder to the image, superimposing a uniformly charged second substrate onto the image face of the first substrate and exposing the rear face of the first substrate to light to transfer the charged image to the second substrate which is developed to produce a high contrast, high density toner image which is then fused. A machine for practicing the method includes a transparent cylinder which may have a photosensitive face or over which a transparent photosensitive sheet is advanced, is reciprocable over the original with the cylinder rolling over the original, a light source having opposite exposure beam delineating slits is located in the cylinder. A pair of charging devices impart uniform charges of the same polarity the transparent sheet or cylinder which obtains a latent electrostatic image by contact with the original and exposure and is then toned by a rotating developing brush and to a copy sheet which is transported into contact with the cylinder or photosensitive sheet and exposed through its rear to transfer a charged image to the copy sheet. The copy sheet is then exposed to the rotating developing brush to transfer additional toner to the image.
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