Patent ID: 8023196

Claim:
A projection lens disposed in a projection device, wherein the projection lens from an image side sequentially comprises: only two lens groups, comprising: a first lens group having a negative refracting power and comprising an aspherical lens surface; and a second lens group having a positive refracting power, wherein a combined total number of lenses in the first and second lens groups is equal to 4; wherein, the first lens group has a first focal length f 1 , the second lens group has a second focal length f 2 , and the first focal length f 1 and the second focal length f 2 satisfy the following two conditions: 0.5 <|f 1 /f 2|<1.5; and −31 mm< f 1<−15 mm; wherein the projection lens has an overall length ranging from 60 mm to 110 mm and an effective focal length ranging from 15 mm to 30 mm.