Illumination apparatus and a projection type image display apparatus using it

Abstract

A projection type image display apparatus for projecting an image onto a screen includes a light source, a beam shape converter, a beam divider, a beam superimposer, a processing unit, and a projection lens. In operation, the light source emits a light beam. The beam shape converter converts a sectional shape of the light beam into a different shape. For example, the beam shape converter can convert a circular cross section into a rectangular cross section. The beam divider then spatially divides the converted light beam into plural light beams. The beam divider can include, for example, a first prism array that divides the converted light beam horizontally and vertically into four beams. The beam superimposer superimposes the plural light beams onto a target surface, such as a liquid crystal panel. The beam superimposer can include, for example, a second prism array and a beam collimator that superimpose the plural light beams on the target surface. The processing unit supplies a signal so as to display an image on the target surface. The projection lens projects the image onto the screen by the superimposed beam. This apparatus can improve the uniformity of illuminance distribution and the light utilization efficiency, while maintaining high directivity of light.