| 摘要 |
PROBLEM TO BE SOLVED: To provide a bright and compact imaging lens capable of being suitably used for a cellular phone or the like and having a large viewing angle. SOLUTION: The imaging lens is equipped with a first negative lens L1 whose surface S1 on an object side is formed to be convex to the object side and whose surface S2 on an image side is formed to be concave to the image side, an aperture diaphragm St, and a second positive lens L2 whose surface S4 on the image side is formed to be convex to the image side in order from the object side. The four surfaces S1 to S4 are all aspherical. The aperture diaphragm St is provided at a position nearer to the second lens than the first lens in terms of a distance on an optical axis. The f-number of the imaging lens is≤4.0 and the half viewing angle thereof is≥25°, and the lens satisfies conditional expressions (1): 0.15<D2/D<0.21 and (2): h2/z2<3.6. Provided that D means the entire length of the lens, D2 means the distance on the optical axis between the surfaces S2 and S3, h2 means the effective radius of the surface S2, and z2 means a distance in an optical axis direction from the apex of the surface S2 to the effective diameter position of the surface S2 in the conditional expressions (1) and (2). COPYRIGHT: (C)2004,JPO&NCIPI
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