Patent ID: 7380968

Claim:
A light source device comprising: a primary light source; a light guide having a light-incident face into which light emitted from the primary light source enters, and a light-emitting face from which guide light is emitted; and an optical deflector element provided adjacent to the light guide on a side of the light emitting-face thereof, wherein the optical deflector element comprising: a light incoming surface into which enters a light emitted from a light-emitting face of a light guide; and a light outgoing surface which is positioned on a side opposite to the light incoming surface and from which the light is emitted, wherein plural elongated prisms are arrayed in parallel with each other on the light incoming surface, and each of the elongated prisms is constituted by a top end flat face having an inclination angle of 1 to 50 degrees and positioned at a top end part of the elongated prism, a first prism face positioned on one side of the top end flat face, and a second prism face positioned on another side of the top end flat face, and wherein an inclination angle of the top end flat face of the optical deflector element is an angle at which peak light emitted from the light-emitting face of the light guide does not enter into the optical deflector element through the top end flat face of the optical deflector element.