US 2015/0146306 A1Published application

Imaging lens

AssigneeKantatsu Co., Ltd.

InventorsTomohiro Yonezawa, Yukio Sekine

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Abstract

A compact low-cost imaging lens which provides brightness with an F-value of 2.5 or less and a wide field of view and corrects aberrations properly, meeting the demand for low-profileness. The imaging lens elements are arranged in order from an object side, an aperture stop, positive first lens having convex object-side and image-side surfaces, negative meniscus second lens having a concave image-side surface, positive third lens having at least one aspheric surface, positive double-sided aspheric fourth lens, and negative double-sided aspheric fifth lens having concave object-side and image-side surfaces with its image-side surface having a pole-change point off the axis. It satisfies conditional expressions below: 0.5<f1/f<1.0 (1) 10.0<f3/f (2) 0.8<(r3+r4)/(r3−r4)<2.0 (3) where f: focal length of the imaging lens overall optical system f1: first lens focal length f3: third lens focal length r3: curvature radius of the second lens object-side surface r4: curvature radius of the second lens image-side surface.

Claims6

Dependent claims

An imaging lens which forms an image of an object on a solid-state image sensor, in which elements are arranged in order from an object side to an image side, comprising:

an aperture stop;
a first lens with positive refractive power having a convex surface on each of the object side and the image side;
a second lens with negative refractive power as a meniscus lens having a concave surface on the image side;
a third lens with positive refractive power having at least one aspheric surface;
a fourth lens with positive refractive power as a double-sided aspheric lens;
and
a fifth lens with negative refractive power as a double-sided aspheric lens having a concave surface near an optical axis on each of the object side and the image side, the image-side surface of the fifth lens having a pole-change point in a position off the optical axis,
wherein conditional expressions (1) to (3) below are satisfied:
0.5<f1/f<1.0 (1)
10.0<f3/f (2)
0.8<(r3+r4)/(r3−r4)<2.0 (3)
where
f:
focal length of an overall optical system of the imaging lens
f1:
focal length of the first lens
f3:
focal length of the third lens
r3:
curvature radius of the object-side surface of the second lens
r4:
curvature radius of the image-side surface of the second lens.

19 more elements

Dependencies are inferred from the claim text.