| 摘要 |
PROBLEM TO BE SOLVED: To obtain a retroreflective sheet satisfying incident angle characteristic, observation angle characteristic and rotating angle characteristic by making the sheet include a prism layer consisting of a retroreflective element having a specified prism apex angle. SOLUTION: Cube corner type retroreflective elements 1 are arranged in a closest packed state to form a prism assembly surface. The top part of a circumferential wall 3 surrounding the prism assembly surface is bonded to a binder layer 6, and a sealed structure including an air layer 7 is formed between the prism assembly surface and the binder layer 6. A retainer layer 5 is formed on the incident side of the binder layer 6. A support layer 9 and an adhesive layer 10 are formed on the surface opposite to the incident side of the binder layer 6. The respective intersection (prism apex angle) formed by two faces of three faces in the retroreflective element 1 is slightly deviated from 90 deg., so that the reflected luminous flux is dispersed only by a slight angle. The apex angle deviation is ±0.001 deg.-±0.2 deg.. |
