Patent ID: 7465083

Claim:
A light guide plate provided with an incidence side end face, a distal side face located oppositely to the incidence side end face, an emission face outputting light inputted from said incidence side end face and a back face located oppositely to the emission face, allowing the light inputted from said incidence side end face to be outputted from said emission face during traveling; at least a part of said emission face providing an emission promotion surface which has a plurality of first slopes and a plurality of second slopes; said first slopes being arranged repeatedly at intervals along a direction from said incidence side end face towards said distal side face; said second slopes being arranged as to fill up the intervals respectively; each of said first slopes being inclined as to have a normal leaning to the distal side face; each of said second slopes being inclined as to have a normal leaning to the incidence side end face and to be steeper than adjacent first slopes on both sides thereof; and wherein inclination angles of said first slopes get smaller gradually with an increasing distance from said incidence side end face.