| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve optical characteristics, while securing miniaturization. <P>SOLUTION: An aperture diaphragm, a biconvex first lens having positive refractive power, a second lens which has negative refractive power and in which an image-side surface is a concave surface, a meniscus third lens having positive refractive power and being convex to an image side, and a fourth lens which has negative refractive power and in which an image-side surface is a concave surface are arranged in order from an object side to the image side. An imaging lens satisfies the following conditional expressions (1) to (5): 0≤(R2+R1)/(R2-R1)≤1 (1), R3≤0 (2), 0.1<D34/f<0.3 (3), -8≤(R6+R5)/(R6-R5)≤-2 (4), R7≤0 (5), where R1 is the radius of curvature of the surface on the object side of the first lens, R2 is the radius of curvature of the surface on the image side of the first lens, R3 is the radius of curvature of the surface on the object side of the second lens, f is the focal length of the entire lens system, and D34 is an air interval between the third lens and the fourth lens. <P>COPYRIGHT: (C)2013,JPO&INPIT |
