Patent ID: 7568805

Claim:
An illumination unit comprising: a plurality of light source units to emit light beams having different wavelengths; and a synthesizing prism to synthesize the light beams emitted from the light source units to proceed on the same path with respect to each other, the synthesizing prism comprising: a first triangular prism comprising a first outer surface to transmit or reflect a first portion of the light beams according to a direction in which the light beams are input, and first and second boundary surfaces, a second triangular prism comprising a second outer surface to transmit a second portion of the light beams, a third boundary surface arranged to face the second boundary surface, and a fourth boundary surface, a third triangular prism comprising a third outer surface to transmit or reflect the first and second portions of the light beams according to a direction in which the light beams are input, a fifth boundary surface arranged to face the fourth boundary surface, and a sixth boundary surface arranged to face the first boundary surface, and a color separation portion arranged at least one of positions between the second boundary surface and the third boundary surface, the fourth boundary surface and the fifth boundary surface, and the sixth boundary surface and the first boundary surface, to selectively transmit or reflect the light beams according to a wavelength of each light beam; wherein the plurality of light units comprises: a first light source unit arranged to face the first outer surface to emit the first light beam toward the second boundary surface, and a second light source unit arranged to face the second outer surface to emit the second light beam toward the third boundary surface.