| 摘要 |
PROBLEM TO BE SOLVED: To provide a novel fixed-focus projection lens configured to adjust focus in accordance with a projection distance.SOLUTION: A projection lens is for projecting an image displayed on an image display element to a projection surface to present a magnified view of the image and is capable of adjusting focus in accordance with a projection distance. The projection lens includes, in order from a magnification side to the image display element side, a first lens group G1 having positive or negative refractive power close to zero, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having positive refractive power, where an aperture stop (Stop) is located in the fifth lens group G5. When adjusting focus, the first lens group G1 and the fifth lens group G5 are stationary, while two or more groups of the second through fourth lens groups G2-G4 move. An effective lens diameter MDi of a lens with the largest effective lens diameter in an i-th lens group (i is 1 through 5) satisfies a magnitude relation expressed as: MD5<MD2<MD3≤MD4<MD1.SELECTED DRAWING: Figure 1 |
