Patent ID: 6457829
Filing Date: 2002-10-01
Classification: G02B,H04N

Abstract:
In a projection device having three optical modulation elements that modulate three respective color-component light beams with image information corresponding to said respective color components, a prism optical system that combines each color-component light beam from the optical modulation elements into a single beam; and a projection lens that receives substantially telecentric light from said prism and projects said light as a magnified image, the improvement of: providing a correction lens that is arranged between the prism optical system and at least one of the optical modulation elements, said correction lens including a curved surface that is convex on the side of the correction lens nearest the optical modulation element, said correction lens correcting for lateral color aberration of the projection lens and having a focal length F defined by the following equationâ€ƒF=DÃ—H/&dgr;whereD is the air conversion length from the liquid crystal panel to the on-axis position of said curved surface, H is the maximum image height at the image before projection, and &dgr; is the lateral color aberration generated by the projection lens.