Patent ID: 7128460

Claim:
An illumination device comprising: a light source to radiate light; a light guide plate to receive the light radiated from the light source through a side surface of the light guide plate and to guide the received light in a surface direction of an upper surface and a lower surface of the light guide plate to perform a surface emission; a hand member disposed at an upper surface side of the light guide plate; and a liquid crystal display member at a lower surface side of the light guide plate; wherein the light guide plate comprises: an upper illuminating portion to guide the received light from the light source in the surface direction and to radiate the light toward the upper surface side of the light guide plate; a lower illuminating portion to guide the received light from the light source in the surface direction and to radiate the light toward the lower surface side of the light guide plate, wherein the lower illuminating portion comprises a plurality of line-shaped prisms having reflection surfaces on the upper surface of the light guide plate, wherein each of the reflection surfaces of the line-shaped prisms is configured to reflect the light guided in the light guide plate toward the lower surface side of the light guide plate, and wherein each of the line-shaped prisms is provided to be approximately in parallel with a line connecting the light source and a portion of a side surface of the light guide plate which faces the light source; and a side surface reflection portion provided on a side surface of the light guide plate adjacent to the lower illuminating portion, to reflect light which is transmitted straight through the lower illuminating portion and reaches the side surface of the light guide plate toward an inside of the lower illuminating portion; wherein the upper illuminating portion comprises a fine concavo-convex portion formed on the lower surface of the light guide plate, and the concavo-convex portion diffusely reflects the light guided in the light guide plate toward the hand member disposed at the upper surface side of the light guide plate.