Abstract: An individual, who is to be subsequently identified, first signs his signature, hereinafter called a template signature, with a special pen, attached to circuits, which produce digital sample signals from which a set of parameters of his signature are derived. This set of template signature parameters is stored in a memory along with sets of parameters derived from template signatures of other individuals. Subsequently, when an individual signs his name with a special pen, the circuits will produce a set of parameters, corresponding to those produced for a template signature. Parameters are selected which can provide strong distinction between signatures. The selected parameters are then used to derive from memory only those sets of template parameters which include the selected parameters which have values falling within a predetermined acceptable range of values.

Abstract: A machine for making a copy on a medium such as paper of a visual image. Particles of toner material are accelerated toward the paper through an apertured screen. Formed on the screen is a pattern of electrostatic charge regions that corresponds to the image so that the arrangement of the toner particles impinging on the paper corresponds to the image. A composite apertured screen composed of two conductive layers separated by an insulative layer and having an insulative layer on one outer surface. Means for establishing oppositely polarized fields across the inner insulative layer and across the outer insulative layer. One of the fields is selectively discharged to control the passage of toner particles through the apertures in the screen.