Patent ID: 8061885

Claim:
A planar illumination device comprising: a light guide plate; point-like light sources arranged on a side end face of the light guide plate; and a frame holding the light guide plate and the point-like light sources, wherein the flame comprises an inner frame formed substantially in a U-shape in a plane of the light guide plate, and an outer frame having a plate-state seat portion and a plurality of side walls installed upright on an outer edge portion of the seat portion so as to accommodate the inner flame; the light guide plate is accommodated in the inner frame and mounted on the seat portion together with the inner frame; the point-like light source is held between the side end face on an open side of the inner flame in the light guide plate and at least one of the plurality of side walls of the outer flame that is opposite the side end face; an inner face side of each side constituting the inner flame is formed in a shape according to each side end face of the light guide plate, and on an outer face side of at least one of the sides constituting the inner flame, an elastic action portion is provided that is elastically deformed by making partial contact with at least one of the plurality of side walls of the outer flame and energizing the light guide plate toward the point-like light source; all of the inner face sides constituting the inner flame are in surface contact with the side end faces of the light guide plate; and the elastic action portion is provided on one side of the inner flame opposite the open side of the inner frame and comprises a thin beam portion and a projection portion projecting outward of the inner frame substantially from the center of the beam portion toward the outer frame, and the inner frame is accommodated in the outer frame with the projection portion in contact with at least one of the plurality of side walls of the outer frame.