Retroreflective sheet structure

1. A retroreflective sheet structure comprising a transparent layer having a front light-receiving surface and a rear retroreflecting surface whereby light incident on the front surface will pass through the layer, impinge on the rear retroreflective surface and reflect back out through the front surface in a predetermined direction;

wherein a large majority of the retroreflective elements have three faces that are planar without any out-thrusts or depressions, wherein at least some of the remaining elements have at least one disturbed face including a planar-disturbance which disrupts the planar profile of the face;

wherein the disturbed faces are arranged in a pattern to collectively form a chosen identifying indicia on the retroreflecting surface;

wherein most of the disturbed face reflective regions remain intact;

wherein identifying indicia becomes visually detectable at an inspection distance of about 20 cm or less; and

wherein the identifying indicia will not interfere with or detract from the retroreflective qualities of the structure.

2. A retroreflective sheet structure as set forth in claim 1 , wherein the retroreflective rear surface of the transparent layer comprises a repeating array of retroreflective elements formed thereon.

3. A retroreflective sheet structure as set forth in claim 2 , wherein the retroreflective elements are corner cubes which each comprise three faces arranged mutually at right angles and connected by edges which join at an apex.

4. A retroreflective sheet structure as set forth in claim 3 , wherein the corner cubes are microcubes having a cube area of about 1 mm 2 or less.

5. A retroreflective sheet structure as set forth in claim 1 , wherein at least 80% of the retroreflective elements have three flat planar faces.

6. A retroreflective sheet structure as set forth in claim 1 , wherein the identifying indicia occupies an area of less than 16 cm 2 on the rear retroreflective surface.

7. An end product incorporating the retroreflective sheet structure set forth in claim 1 , the end product including a mounting surface to which the retroreflective sheet structure is attached.

8. An end product as set forth in claim 7 , wherein the retroreflective sheet structure is adhesively attached to the mounting surface.

9. An end product as set forth in claim 7 , wherein the end product is a vehicle, a highway sign, or a barrel.