Projection lens system for a video projector

摘要

A projection lens system for a video projector for projecting a color image which is generated by combining red, green and blue images from an image source on a large screen. One lens element of a four lens optical lens system is disposed between an image-generating surface (or CRT) and an image combining unit for combining the images, and an oil chamber is provided by sealing the edges of the lens element and the image-generating surface. The flattening of the CRT's image-generating surface and a large aperture are attained by allowing the one lens to correct field curvature aberration and the other lenses to correct coma aberration. Separate cooling for respective CRTs enhances cooling devices efficiency and facilitates CRT movement adjustment for correcting chromatic aberration.