Electrography
Electrography is a subset of electrophotography that uses similar processes but does not include exposure of a photo-sensitive receiver element. There are direct and indirect forms of electrography.
Direct electrography employs a means of writing an electrostatic charge on an insulating surface that will be the final print. Various elements have been used for placing the charge on the print media. Usually an array of pins is used. The actual mechanism of charging is known as Paschen discharge and it takes place when the very small air gap between the end of the pin and the media reaches ionization.
Typically the print media is paper that has been coated with a thin insulating layer and a ground plane or electrode is placed on the surface of the media opposite to the writing pins. After the charge has been written on the surface it is developed using a toner development system as in electrophotography. After the image is developed it is usually fixed by heat thereby providing the print.
Indirect electrography uses a similar electrostatic system but writes to an intermediate element, develops the toner image on that element and then transfers the image to paper. In the best known implementation by Delphax, the intermediate is an anodized drum and the writing element is a proprietary electron beam array.