Patent ID: 7331680

Claim:
An illumination unit comprising: first, second, and third light source units to emit first, second, and third light beams of different wavelength bands, respectively; a first triangular prism including a first entrance surface through which the first light beam emitted from the first light source unit is incident, a first exit/reflection surface inclined with respect to the first entrance surface to transmit or reflect incident light according to an incident angle of the incident light, and a second entrance surface on which the first light beam reflected by the first exit/reflection surface and the second light beam emitted from the second light source unit are incident; a second triangular prism including a third entrance surface through which the third light beam emitted from the third light source unit is incident, a second exit/reflection surface inclined with respect to the third entrance surface to transmit or reflect incident light according to an incident angle of the incident light, and a fourth entrance surface facing the first exit/reflection surface to be spaced a predetermined distance from the first exit/reflection surface of the first triangular prism and allowing the third light beam reflected by the second exit/reflection surface and the first and second light beams transmitted through the first exit/reflection surface to be incident therethrough; a first color filter formed on the second entrance surface of the first triangular prism to reflect the first light beam incident from the first exit/reflection surface and to transmit the second light beam such that the first light beam and the second light beam are directed toward the first exit/reflection surface; and a second color filter formed on the fourth entrance surface of the second triangular prism to reflect the third light beam incident from the second exit/reflection surface and to transmit the first and second light beams transmitted through the first exit/reflection surface such that the first, second, and third light beams are directed toward the second exit/reflection surface.