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593,045 · Cummings · "Light-Transmitter" · Page 2 Home  > Prism Glass  > Patent Index  > Page 2

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and will emerge from the convex surfaces. By reason of the shape of the convex projections the rays of light that are parallel when passing through the pane, when they emerge therefrom, will be localized along a line some distance beyond the convex surface and after passing the focal line will diverge, so as to spread and diffuse the light. In most cases, in addition to the rays of light coming from the main general direction, there is a large number of rays reflected from adjoining objects and falling on the incident surface from almost every direction. These rays will emerge from the convex projections in every direction within the limits of the convex surface of the said projections, and the light emerging from each convex projection will therefore spread out or radiate beyond its focal lines into a fan-like form or space, and the fan-shaped area of light from one convex projection will overlap the fan-shaped area of light from the adjoining projection. In this way the light is not only thoroughly spread and diffused, but it is made even and of maximum intensity. Very little, if any, light is lost by internal reflection.     As the projections and the intervening septum of the plate are made integral, it follows that rays of light falling on the incident surface opposite one of the convex projections, but at such an angle that they cannot emerge from the convex projection, will, nevertheless, emerge from the adjoining convex projection, and in this way be saved and utilized.     In some cases where the outside light is rather diffused the convex projections may be used as the incident side; but I have secured the best results in the manner above described. In Fig. 3 I have illustrated by means of a few lines representing rays of light the direction which those rays would take if the convex surface were incident.

This convex surface may be conceived of as made up of an infinite number of planes, and the rays of light coming from many different directions strike these planes at angles of incidence that minimize the reflection, so that the greatest possible amount of light enters the plate. These rays pass through the plate in their several and numerous directions and are refracted in a diffused manner and in divergent directions from the plane prism-surfaces.     What I claim as new, and desire to secure by Letters Patent, is—     1. As a new article of manufacture, a pane or light made of a single piece of translucent material and provided on one side with a series of parallel triangular prismatic ribs or projections and on the other side with a series of parallel convex projections, the convex surface of each projection being bounded by an arc of a circle, the arc of each projection joining or intersecting the arcs of the adjacent projections, and the convex projections being parallel with the triangular projections, substantially as set forth.     2. As a new article of manufacture, a pane or light made of a single piece of translucent material and provided on one side with a series of parallel triangular prismatic ribs or projections, and on the other side with a series of parallel convex projections, the convex surface of each projection being bounded by an arc of a circle, the arc of each projection joining or intersecting the arcs of the adjacent projections, and the convex projections being parallel with the triangular projections and being placed opposite thereto, substantially as set forth. GEORGE K. CUMMINGS. Witnesses:     S. S. STOUT,     W. T. CASGRAIN.