Patent ID: 7242530

Claim:
A projection display system, comprising: an illuminating system generating a light; an optical engine displaying an image according to an image signal; and a projection lens system enlarging the image transmitted from the optical engine and projecting the enlarged imaged on a screen, wherein the projection lens system comprises a first lens group having a negative refractive power, a second lens group having a positive refractive power and a total reflection mirror arranged between the first lens group and the second lens group, wherein the arrangement of the first lens group, the second lens group and the total reflection mirror satisfies the following conditions: 3.2< bfl/fl< 3.5, 0.75<| f 2/ f 1|<1.0, and 5.0< d 8/ fl< 7.0, wherein bfl represents a distance between the optical engine and the second lens group, fl represents a total focal length of the projection lens system, f1 represents a focal length of the second lens group, f2 represents a focal length of the first lens group, and d8 represents a distance between the first lens group and the second lens group.