Method for forming retroreflective sheeting
US4243618A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 23, 1978 |
| Grant date | Jan 6, 1981 |
| Priority date | — |
| Expiry date | Oct 23, 1998 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T29/49813
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A method is disclosed for forming a retroreflective sheeting having a plurality of retroreflective cube-corner prisms distributed over one of its surfaces such that the prisms are disposed in a planar array having a plurality of zones of prisms having differing angular orientations such that the zones have differing retroreflective brightness when illuminated by a light beam at a high angle of incidence. The method comprises clamping a plurality of pins together such that the ends of the pins form a substantially planar surface, inscribing the planar surface for forming thereon a continuous pattern of solid trigonal pyramids with internal dihedral angles of 90 degrees, releasing the bundle of pins and rotating the individual pins for changing the angular orientation of the formed trigonal pyramids on adjacent pins, reclamping the pins together and using the inscribed surface of the bundle of pins for forming a mold containing cube-corner prism cavities, and producing prismatic retroreflective sheeting by embossing, molding or casting in such mold.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.