Reading device

Claim 1

A reading device for viewing microfilms, transparencies, fiches and the like, said device comprising: a plate-shaped projecion screen made of transparent material, said screen being inclined to the horizontal at an acute angle and having upper and lower ends and opposite sides, said screen having on one side a frosted surface, said surface constituting the viewing side of the screen; prism-shaped parts disposed on the opposite side of the projection screen; a source of light on said opposite side of the screen; a carrier for placing thereupon microfilms, transparencies and fiches to be projected; and a mirror assembly disposed to reflect rays of light from said source of light thorugh said prism-shaped parts upon and through said projection screen, said prism-shaped parts being disposed in lengthwise rows and having prism surfaces extending at an angle with respect to said opposite side of the projection screen for deflecting light rays reflected from the mirror assembly so as to project an image of the article placed on the carrier within an angle converging toward a viewer situated above and in front of the screen at an acute viewing angle with respect to said screen, said prism surfaces progressively increasing in angle with respect to the opposite side of the projection screen from the lower end of the screen whereat said angle is substantially zero toward the upper end of the screen whereat said angle is maximum to provide substantially uniform illumination within the visual angle of the observer.