Retroreflective sign having improved legibility

• US 5,050,327 A
• Filed: 11/17/1989
• Issued: 09/24/1991
• Est. Priority Date: 11/17/1989
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Inventors: Woltman, Henry L.
• Primary Examiner(s): SILBERMANN, JOANNE
• Assistant Examiner(s): Bonifanti, J.
• Application Number:
  US07/438,691
• Time in Patent Office: 676 Days
• Field of Search: 40/582, 40/903, 40/615, 350/101, 350/103, 350/109
• US Class Current: 40/582
• CPC Class Codes: G09F 13/0472 Traffic signs
• CPC Class Codes: G09F 13/16 Signs formed of or incorporating reflecting elements or surfaces, e.g. warning signs having triangular or other geometrical shape

Abstract

A sign having a face bearing an informational legand thereon, the face comprising at least one legend portion and at least one background portion, and the sign comprising at least one legend segment and at least one background segment, which segments are defined by the legend and background portions, wherein at least part of at least one of the legend and background segments is retroreflective and translucent. The segments of the signs which are translucent and retroreflective exhibit increased luminance under adverse lighting conditions, thereby increasing the conspicuity and legibility of the sign.

Claims

1. A sign located adjacent a road having a face bearing an informational legend thereon, said face comprising at least one legend portion and at least one background portion, each of said legend portions of said face defining a cross-sectional legend segment of said sign, said legend segment extending from said legend portion through the entirety of said sign, and each of said background portions of said face defining a cross-sectional background segment of said sign, said background segment extending from said background portion through the entirety of said sign,

wherein at least one of said legend and background segments is both retroreflective and translucent such that light incident to the front surface of said retroreflective and translucent segment is retroreflected and light incident to the back surface of said retroreflective and translucent segment is transmitted through said front surface.

2. The sign of claim 1 wherein said translucent segment has a retroreflective brightness of at least about 1 candela per lux per meter² at an observation angle of 0.2°

and an entrance angle of -4°

.

3. The sign of claim 1 wherein said translucent segment has a retroreflective brightness of at least about 5 candela per lux per meter² at an observation angle of 0.2°

and an entrance angle of -4°

.

4. The sign of claim 1 wherein said translucent segment has a retroreflective brightness of at least about 50 candela per lux per meter² at an observation angle of 0.2°

and an entrance angle of -4°

.

5. The sign of claim 1 wherein said translucent segment has a retroreflective brightness of at least about 100 candela per lux per meter² at an observation angle of 0.2°

and an entrance angle of -4°

.

6. The sign of claim 1 wherein said translucent segment has a retroreflective brightness of at least about 1000 candela per lux per meter² at an observation angle of 0.2°

and an entrance angle of -4°

. PG,18

7. The sign of claim 1 further comprising a backing member.

8. The sign of claim 7 wherein said backing member comprises at least one of the following:

polycarbonate, polymethylmethacrylate, modified acrylics, polyester, or epoxy.

9. The sign of claim 7 wherein said backing member comprises a coloring agent.

10. The sign of claim 1 wherein said legend and said background portions of said face are of legibility-enhancing contrasting colors.

11. The sign of claim 1 wherein at least a part of said legend portion is black.

12. The sign of claim 1 wherein at least a part of said background portion is at least one of white, blue, brown, orange, yellow, red, or green.

13. The sign of claim 1 wherein at least part of said translucent segment is also fluorescent.

14. The sign of claim 1 wherein the transmittance of said legend segment is at least 10 percent different from the transmissivity of said background segment.

15. The sign of claim 1 wherein the effective transmittance of said translucent segment is at least about 0.01 as determined in accordance with ASTM D 1003-61, Procedure B.

16. The sign of claim 1 wherein the effective transmittance of said translucent segment is at least about 0.02 as determined in accordance with ASTM D 1003-61, Procedure B.

17. The sign of claim 1 wherein the effective transmittance of said translucent segment is at least about 0.05 as determined in accordance with ASTM D 1003-61, Procedure B.

18. The sign of claim 1 mounted on a support in a substantially optically-non-interfering manner.

19. The sign of claim 1 further comprising a coloring member.

20. The sign of claim 7 wherein said backing member is translucent and white.