Abstract: An applicator for depositing toner particles onto an electrostatically-charged latent image formed on a photoconductive insulating layer to render visible and develop this image. The applicator includes a trough containing a supply of toner and provided with a flexible blade of dielectric material which engages the surface of a rotating carrier roll to form a tight nip. As the roll turns, toner particles at the bottom of the trough are advanced toward the blade and forced through the nip, the blade being deflected to admit a thin layer of particles which adhere to the roller surface. In the course of such passage, the particles are frictionally rubbed by the edge of the blade and thereby caused to assume a triboelectric charge.

Abstract: Apparatus for the elimination of noxious ammonia fumes associated with diazo copiers includes a plenum chamber disposed about the output aperture of the machine developer chamber. Vacuum means are provided to draw the ammonia laden air out of this chamber. Preferably this apparatus is used in conjunction with a novel filter connected between the chamber and the vacuum means. The filter comprises a filter body of a material such as corrugated paper having a plurality of longitudinal substantially parallel channels, the walls of which are impregnated with a material, such as phosphoric acid, which will react with ammonia to generate odorless end products. A granular layer impregnated with such a material may be disposed in contact with the output end of this filter body.