LOW-GLARE OVERHEAD PROJECTOR

摘要

An overhead projector is disclosed which has in optical alignment a light source, a transparent surface on which a transparency is laid for projection, and echelon lens structure located between the light source and the surface, and a projection lens for focusing an image of the transparency onto a projection screen. The echelon lens structure comprises at least two linear echelon lenses which are oriented so that their cylinder axes are crossed at an angle greater than 0.degree. and so that the lens structure achieves focusing of an image of the light source, whereby a user of the projector is not disturbed by "propeller"-type concentrated glare emanating from the lens structure.