Light guide film with cut lines, and optical keypad using such film

摘要

A light guide includes a light interface surface, top and bottom surfaces, a surface feature pattern, and a cut line. The light interface surface receives light into the light guide from a light source. The light received through the light interface surface reflects according to total internal reflection (TIR) within the light guide between portions of the top and bottom surfaces. The surface feature pattern disrupts the TIR and scatters at least some of the light outside of at least one surface of the top and bottom surfaces. The cut line redirects at least some of the light from a first direction to a second direction within the light guide. The first direction is a direction other than towards the surface feature pattern, while the second direction is a direction substantially towards the surface feature pattern. The light guide may back-illuminate an optical keypad with a plurality of push buttons.