Patent ID: 7563013

Claim:
A light guide plate adapted for use with at least one light source that is capable of providing source light beams, said light guide plate comprising: a plate body; and a plurality of light-guiding structures that are distributed on said plate body, each of said light-guiding structures being in a substantially quadrilateral pyramidal form, and including a quadrilateral lower end that has four corners, and a tapered upper end that is disposed opposite to said lower end, each of said light-guiding structures further including four sides, each of which is defined by said upper end and a corresponding adjacent pair of said corners, adjacent ones of said sides being interconnected; wherein said plate body includes opposite upper and lower sides, the source light beams provided by the light source entering said light guide plate through a side edge thereof that interconnects said upper and lower sides; and wherein said light-guiding structures are capable of changing optical paths of light beams propagating through said light guide plate such that the light beams exit said light guide plate with angles relative to a normal of said upper side of said plate body that fall within a predefined range; wherein said predefined range is between 55 to 75 degrees to generate the greatest luminance of 6000 cd/m.sup.2 so as to concentrate the light beams which exits the light guide plate; each of said light-guiding structures has a first boundary edge connecting a first pair of said corners and extending to said upper end, and a second boundary edge connecting a second pair of said corners and crossing said first boundary edge at said upper end, each of said light-guiding structures being symmetrical relative to said first and second boundary edges.