Patent
1974-10-22
1976-05-04
Corbin, John K.
350 97, 350104, 350102, 350106, G02B 5136
Patent
active
039543242
ABSTRACT:
A pavement marker including a housing having a base for engagement with the surface of a roadway and a reflective wall for reflecting light from vehicles on the roadway when the fore-and-aft axis of the housing is disposed in parallel relationship with the direction of travel of vehicles on the roadway. The central portion of the reflective wall is formed with a plurality of conical reflector elements having relatively high optical efficiency for reflecting incident light rays on the outer surface of the reflective wall that are substantially in a horizontal plane parallel to the plane of the base and that are substantially parallel to the fore-and-aft axis of the housing, but having relatively low optical efficiency for reflecting light rays making a substantial acute angle with respect to the plane of the base or the fore-and-aft axis of the housing. Wide angle reflector elements are formed on side portions of the reflective wall projecting from opposite ends of the central portion. The wide angle reflector elements are of a configuration other than conical and have less optical efficiency than the conical reflector elements for reflecting incident light rays on the outer surface of the reflective wall that are substantially in a horizontal plane parallel to the plane of the base and that are substantially parallel to the fore-and-aft axis, but have greater optical efficiency than the conical reflector elements for reflecting incident light rays that make a substantial acute angle with the plane of the base or the fore-and-aft axis of the housing. The conical reflector elements each have an apex located remotely from the outer face of the reflective wall and an axis passing through the apex and lying in a plane that is perpendicular to the plane of the base and parallel to the fore-and-aft axis of the housing, the axis of each of the conical reflector elements extending at an acute angle with respect to the normal to the outer face such that the conical reflector elements are oriented to receive incident light refracted from the outer face and reflect the light in a direction substantially parallel to the direction of incidence. The wide angle reflector elements are of the cube corner type in the preferred embodiment. In a modified embodiment, the wide angle reflector elements are of spherical configuration, the spherical reflector elements providing good wide angle performance but having lower optical efficiency than the cube corner reflector elements.
REFERENCES:
patent: 1643420 (1925-01-01), Porter
patent: 1675431 (1928-07-01), Shapp
patent: 1743835 (1923-07-01), Stimson
patent: 2181725 (1936-12-01), Eckel
patent: 3627403 (1971-12-01), Hedgewick
patent: 3873184 (1975-03-01), Heenan
Arnott Robin A.
Domaracki John F.
Corbin John K.
DE LOS Reyes Ben Wm.
International Tools (1973) Limited
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