Patent ID: 8462293

Claim:
An illuminating device comprising: a plurality of combinations each including: at least one point light source, and a light guide plate for causing light from the at least one point light source to be diffused and surface-emitted, the light guide plate including (i) a light-emitting section having a light-emitting surface and (ii) a light guide section for guiding the light from the at least one point light source to the light-emitting section, a light-emitting section of one of any adjacent two light guide plates in the plurality of combinations being provided above a light guide section of the other of the any adjacent two light guide plates in the plurality of combinations, a following expression being satisfied X<Y where Y is a length of the light-emitting section in a length direction, and X is a length of the light guide section in the length direction, the length direction being a direction pointing from the at least one point light source toward the light-emitting section, a reflecting sheet being sandwiched between the light guide plate and a substrate having the light source, and wherein a length of the light guide section provided between the at least one point light source and the light-emitting section being set so that an area, on a boundary surface between the light-emitting section and the light guide section, of a cross-section of a light beam that is emitted from the at least one point light source and is diffused in the light guide plate is equal to or larger than an area of the boundary surface.