Abstract: A real image direct front projector includes a housing with a plane transparent object support for placing objects thereunder and for permitting light emitted from at least one light source to pass therethrough. A projection lens is mounted concentrically above the object support for producing an object image on an image wall outside of the projector. The projection lens is located above and vertically within the circumference of the object support. The object support has in at least a predetermined area thereof a plurality of microprisms on a side of the object support facing away from the object.

Abstract: This invention is for an overhead projector to be used with at least one large stage aperture and a small stage aperture above a Fresnel lens, comprising a light source mounted below the plane of the stage, characterized by a single or multi-element condenser which can be positioned between the lamp housing and Fresnel lens. In the case of a small stage aperture, the condenser focuses the light flux designed for the large stage aperture onto the small stage aperture.

Abstract: The invention concerns a transparency overhead projector having an illumination unit of which the height has been extremely reduced. The main component of the illumination unit is a specular surface comprising mutually parallel, mirrorized prismatic shoulders either on its top or on its lower side, which reflect the light from at least one lateral source toward the Fresnel lens, the platen and the projecting lens. The specular surface may be plane, however it may also be curved in circular, hyperbolic etc. manner in the longitudinal direction of the prismatic shoulders. This curvature may be constant or it may vary. Further, the specular surface also may be twisted, that is, it may also be curved in a direction orthogonal to the prismatic shoulders, and this curvature also may be constant or variable.