Roadway sign
AssigneeMinnesota Mining and Manufacturing Company
InventorHenry L. Woltman
Life of this patent
Estimating the term…
Abstract
An improved roadway sign comprising a light retroreflective indicia region and colored retroreflective background region is provided. The retroreflective properties of the regions are selected such that the ratio of the retroreflective brightness of the indicia to that of the background is substantially larger at observation locations within the legibility zone for the sign, than the ratio is at observation locations outside the legibility zone. The sign is conspicuous by virtue of the bright retroreflection and distinctive color of the background outside the legibility zone, yet is legible because of the increased contrast ratio of the indicia to the background in the legibility zone.
Claims9
A sign comprising a retroreflective background region and a retroreflective indicia region, wherein the retroreflective properties of said regions are selected such that the ratio of retroreflective brightness of said indicia to the retroreflective brightness of said background is substantially larger at locations within the legibility zone for the sign, than said ratio is at locations outside the legibility zone.
A sign comprising a retroreflective background region and a retroreflective indicia region, wherein the retroreflective properties of said regions are selected such that the ratio of retroreflective brightness of said indicia to the retroreflective brightness of said background is at least 10:1 at an observation angle of 0.5.degree., and said ratio is less than about 6:1 at an observation angle of 0.1.degree..
Dependencies are inferred from the claim text.