Patent ID: 8203792

Claim:
A projection lens comprising, from a long conjugate side to a short conjugate side, a first lens unit with positive optical power, a second lens unit with negative optical power, and a third lens unit with negative optical power, wherein the first lens unit is configured for correcting chromatic aberration of the projection lens; the third lens unit comprises a meniscus lens which is convex toward to the short conjugate side of the projection lens; the projection lens satisfies conditions: 0.1 < f 2 ⁢ / ⁢ f 3 < 0.4 ; ( 1 ) 0.6 < f 1 ⁢ / ⁢ f < 0.9 ; ( 2 ) 1.2 < BFL ⁢ / ⁢ h < 1.6 ; ( 3 ) 0.7 < f ⁢ / ⁢ BFL < 1.2 ; ( 4 ) wherein f represents a focal length of the projection lens, f 1 represents a focal length of the first lens unit, f 2 represents a focal length of the second lens unit, f 3 represents a focal length of the third lens unit, BFL represents a back focal length of the projection lens, h represents an object height.