Patent ID: 8491125

Claim:
A lighting device comprising: a plurality of light sources; a plurality of converging lenses for converging respective light beams emitted from the light sources; a right-angle prism for bending the light beam emitted from one of the light sources; and a composite rod integrator for combining the light beams emitted from the plurality of light sources; wherein a predetermined air gap is provided between an exit surface of the right-angle prism and an incident surface of the composite rod integrator, the focal point of one of the plurality of converging lenses is located on an incident surface of the right-angle prism, and the lighting device is configured to satisfy the following condition: | n 1sin (π/2-2 θi+sin −1 ((sin(θc))/ n 1)|<1, where θi: angle formed between a central axis of the light beam entering the right-angle prism and a line perpendicular to the inclined surface of the right-angle prism, θc: angle formed between the light beam that is outputted from the converging lens and incident on the incident surface of the right-angle prism at the largest incident angle, and the optical axis of the converging lens, and n1: refractive index of material forming the right-angle prism.