Electrostatic document copying machine - exposes original and dielectric coated sheet between capacitor plates with latent image developed by toner

摘要

The copying procedure for documents is based on the different dielectric properties of the written or printed characters and the white spaces between them. The original and a dielectric coated sensitive surfaces are exposed to an electric field between the plates of a condenser, so that a latent image is formed which can be developed in known fashion using a toner. The condenser voltage is between 500 and 5000 volts, and pref. between 2000 and 4000V. Positive or negative copies, direct or inverted, may be obtained by control of the polarity of the field and the relative positions of original and copy sheet. The dielectric layer is pref. an artificial resin of the polystyrol or polyvinylcarbazole groups.