Patent ID: 7492520

Claim:
A light source apparatus comprising: a light-emitting portion; a light-guiding plate having the light-emitting portion disposed at a side surface thereof, light beams being emitted from a top surface of the light-guiding plate; and a light path converting sheet above the light-guiding plate, formed of a prism sheet including cylindrical prisms, a cross-section of which is a polygon obtained by deforming an isosceles triangle; wherein each of the prisms on the prism sheet includes at least a first light incidence plane that forms a first equilateral constituting one surface of each of the prisms associated with an apex angle of the isosceles triangle, a first reflection plane that forms a base of the isosceles triangle, and a second light incidence plane that forms one side of the polygon, a second reflection plane that forms another side of the polygon and a light exit plane that forms a second equilateral constituting another surface of each of the prisms associated with the apex angle of the isosceles triangle, an angle formed with the second reflection plane and the light exit plane being equal to an angle formed with the second reflection plane and the second light incidence plane, and wherein each of the prisms is disposed such that the first light incidence plane is approximately perpendicular to a direction of light beams with highest luminous intensity and that the second light incidence plane is approximately perpendicular to a direction of light beams with second highest luminous intensity, among the light beams emitted from the top surface of the light-guiding plate.