Patent ID: 8714745
Filing Date: 2014-05-06
Classification: G02B,G03B

Abstract:
1. A projection display apparatus comprising: a first reflection type image display element configured to display an image; a second reflection type image display element configured to display an image; a third reflection type image display element configured to display an image; an illumination optical system configured to illuminate the first, second and third reflection type image display elements using light from a light source; a color splitter and combiner system; and a projection optical system configured to project image light from the color splitter and combiner system, onto a screen, wherein the color splitter and combiner system includes: a first polarization beam splitter configured to lead first color light to a first reflection type image display element and to analyze first reflected light from the first reflection type image display element; a second polarization beam splitter configured to lead second color light to a second reflection type image display element, to analyze second reflected light from the second reflection type image display element, and to lead third color light to a third reflection type image display element, and to analyze third reflected light from the third reflection type image display element; an optical path combiner configured to combine the first color light emitted from the first polarization beam splitter with the second color light and the third color light that are emitted from the second polarization beam splitter; a first transparent plate located on an optical path between the first polarization beam splitter and the optical path combiner; and a second transparent plate located on an optical path between the second polarization beam splitter and the optical path combiner, wherein 0.05(mm)<|t1/ν1−t2/ν2|<1.00(mm) is met, where t1 is a thickness of the first transparent plate, t2 is a thickness of the second transparent plate, ν1 is an Abbe number of a material of the first transparent plate, and ν2 is an Abbe number of a material of the second transparent plate, and wherein an interference pattern in the image light projected on the screen by the projection optical system would be created unless the projection display apparatus includes the first and second transparent plates.