GB531467A - Improvements in or relating to vision apparatus - Google Patents

Abstract

531,467. Signs. STEVENS, A. H. (Trafficscope Inc.). April 28, 1939, No. 12754. [Class 3 (ii)] [Also in Group XX] In order to afford unrestricted view along a highway where visibility is restricted as by a hillcrest or bend, a lighttransmitting refracting device is erected over the highway at or near the crest &c. The device at a crest may comprise a series of horizontal rows of prism-lenses 26, Fig. 3, located one above another in a framework 29 trunnioned (to permit yielding to. wind pressure) at 30 in a supporting structure 25 spanning the crest. The prism-lenses 26 have their refracting edges horizontal and upper most, Fig. 10, and have one plain face and one concave cylindrical face 28, but both faces may be concave cylindrical, and preferably the cylindrical faces all have the same radius of curvature. The prism-lenses have increasing refracting power downwards from row to row, and the assembly preferably spans from one quarter to three quarters of the width of the highway. Protection from the weather is afforded by a hood and side wings. The prismlenses may be solid, and of glass or plastic material, e.g., a vinyl resin; or they may be glass vessels filled with liquid which may be non-freezing, e.g., a mixture of methanol and a solution of calcium chloride. In addition to or instead of the prism-lenses 26, a set of prisms 41, Fig. 10, with their refracting edges vertical may be similarly supported where visibility round a bend is desirably in 'addition to or instead of visibility beyond a crest.