US 9,541,735 B2Granted

Imaging lens

AssigneeKantatsu Co., Ltd.

InventorTomohiro Yonezawa

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Abstract

A compact low-priced imaging lens which offers a field of view of about 180 degrees and high optical performance. The imaging lens for a solid-state image sensor includes, in order from an object side to an image side, a first lens with negative refractive power having a convex object-side surface and an aspheric image-side surface; a second lens with negative refractive power as a double-sided aspheric lens having a concave surface on the image side; a third lens with positive refractive power; an aperture stop; and a fourth lens with positive refractive power. The first and second lenses are made of plastic material. The imaging lens satisfies conditional expressions (1) and (2) below: −65.0<f1/f<−17.0 (1) 0.04<f2/f1<0.14 (2) where f: focal length of the overall optical system of the imaging lens f1: focal length of the first lens f2: focal length of the second lens.

Claims3

Dependent claims

An imaging lens in which elements are arranged in order from an object side to an image side, comprising:

a first lens having negative refractive power, a convex surface on the object side, and an aspheric surface on the image side;
a second lens as a double-sided aspheric lens having negative refractive power and a concave surface on the image side;
a third lens having positive refractive power;
an aperture stop;
and
a fourth lens having positive refractive power,
wherein the first lens and the second lens are made of plastic material;
and
conditional expressions (1b), (2b), (3b), (4b), and (5b) below are satisfied:
−50.76≦f1/f≦−21.63 (1b)
0.06≦f2/f1≦0.12 (2b)
6.09≦f3/f≦7.64 (3b)
2.03≦f4/f≦2.41 (4b)
18.01≦TTL/f≦20.34 (5b)
where
f:
focal length of an overall optical system of the imaging lens
f1:
focal length of the first lens
f2:
focal length of the second lens
f3:
focal length of the third lens
f4:
focal length of the fourth lens
TTL:
distance on an optical axis from the object side surface of the first lens to an image plane.

24 more elements

Dependencies are inferred from the claim text.