Abstract: The end surface of the light guide plate has a flat surface and a protruding surface which protrudes with respect to the flat surface. Light traveling from the light source in a direction perpendicular to the flat surface enters the light guide plate in an expanded manner due to refraction at the protruding surface. The protruding surface has a shape in which cylindrical surfaces are integrated, the respective cylindrical surfaces being formed about central axes which are orthogonal to the front surface from which the light exits. A pair of cylindrical surfaces, which is positioned at both end portions of the protruding surface in an arraying direction of the cylindrical surfaces, is each adjacent to the flat surface. Adjacent cylindrical surfaces are connected to each other at a position shifted in a protruding direction of the protruding surface with respect to the flat surface.

Abstract: The end surface of the light guide plate has a flat surface and a protruding surface which protrudes with respect to the flat surface. Light traveling from the light source in a direction perpendicular to the flat surface enters the light guide plate in an expanded manner due to refraction at the protruding surface. The protruding surface has a shape in which cylindrical surfaces are integrated, the respective cylindrical surfaces being formed about central axes which are orthogonal to the front surface from which the light exits. A pair of cylindrical surfaces, which is positioned at both end portions of the protruding surface in an arraying direction of the cylindrical surfaces, is each adjacent to the flat surface. Adjacent cylindrical surfaces are connected to each other at a position shifted in a protruding direction of the protruding surface with respect to the flat surface.