Retroreflector for road surfaces

Claim 1

A retroreflective assembly for mounting on roadways and the like comprising: A. an elongated housing of substantially transparent material having a base surface, a top surface, and side surfaces extending along the length thereof, said base surface defining a base plane upon which said housing may be supported, said housing having a channel extending perpendicularly upward from said base surface and terminating at a point spaced from said top surface by a predetermined distance, at least one of said side surfaces of said housing having a longitudinally extending planar light-reception surface portion lying in a plane that intersects an imaginary line extension of said channel at a point spaced above said top surface and at a predetermined acute angle; and B. an elongated strip of retroflective sheet material snugly seated in said channel with a retroflective face disposed towards said planar surface portion of said housing, said retroreflective sheet material having retroreflective formations of cube-corner configuration spaced from said retroreflective face; said predetermined spacing of said channel from said top surface being at least 0.020 inch; the distance between said base surface and said top surface being less than 0.30 inch; said predetermined acute angle being at least 8°, the refractive index of the housing material cooperating with said acute angle to cause light rays impinging on said planar surface portion to be refracted downwardly onto said retroreflective face of said strip and reflected therefrom outwardly through said planar portions in a direction substantially parallel to that of incidence thereon, the apparent position of said strip from a viewpoint of less than 8° above said plane of said base thereby being higher than the actual position of said strip; and said housing providing an opaque upper surface, said retroreflective strip thereby being projected from sunlight impinging on said housing from above.