ILLUMINATING OPTICAL SYSTEM, IMAGE DISPLAY UNIT AND METHOD OF ILLUMINATING SPACE MODULATION ELEMENT

摘要

An illuminating optical system excellent in color rendering with a sufficient illuminance ensured, an image display unit provided with such an illuminating optical system and a space modulation element illuminated by this, and a method of illuminating such a space modulation element. The system comprises a first light source (11), a second light source (21) having an emission spectrum different from that of the first light source (11), and a replacing optical system for replacing a light beam in a specific wavelength band out of a light flux (L1) from the first light source (11) with a light flux (L2) from the second light source (21), a weak-light-intensity light beam in a specific wavelength band in a light flux (L1) from the first light source (11) being replace by a light flux (L2) from the second light source (21) having a sufficient intensity. Accordingly, white balance can be ensured without lowering in illuminance more than necessary to deliver an excellent color rendering performance.