Projection lens system

摘要

A projection lens system for projecting an enlarged image onto a display screen front an image appearing on a faceplate of a cathode ray tube utilizes at least six lens groups. The first lens group, from an end closest to the display screen, is in a form of a meniscus having a negative power. The second lens group has a weak positive power and a convex surface towards the display screen. The third lens group has a strong positive power. The fourth lens group is bi-convex and has a strong positive power. The fifth lens group has a weak positive power. The sixth lens group has a negative power and a pronounced concave surface away from the display screen. The second and fifth lens groups each are made with plastic lenses with at least aspheric surfaces on one side.