US 8,576,496 B2Granted

Imaging lens system

AssigneeLargan Precision Co., Ltd.

InventorsDung-Yi Hsieh, Tsung-Han Tsai, Wei-Yu Chen

Life of this patent

Estimating the term…

Loading patent…

Abstract

This invention provides an imaging lens system comprising two non-cemented lens elements with refractive power: a positive first lens element having a convex object-side surface at a paraxial region and a convex or flat image-side surface at the paraxial region; and a negative second lens element having a concave object-side surface at a paraxial region and a concave image-side surface at a paraxial region, and both the object-side and image-side surfaces being aspheric; wherein, the shape of the image-side surface of the second lens element changes from concave when near an optical axis to convex when away from the optical axis. By such arrangement, the imaging lens system has not only a shorter total track length for compact electronic products, but also the advantage of a more comparable focusing performance between the short wavelength and long wavelength applications with improved image quality.

Claims19

Dependent claims

An imaging lens system, in order from an object side to an image side comprising two non-cemented lens elements with refractive power:

a positive first lens element having a convex object-side surface at a paraxial region thereof and a convex or flat image-side surface at the paraxial region thereof;
and
a negative second lens element having a concave object-side surface at a paraxial region thereof and a concave image-side surface at a paraxial region thereof, and both the object-side and image-side surfaces being aspheric;
wherein, the shape of the image-side surface of the second lens element changes from concave when near an optical axis to convex when away from the optical axis;
wherein an Abbe number of the first lens element is V1, an Abbe number of the second lens element is V2, a curvature radius of the object-side surface of the first lens element is R1, a curvature radius of the image-side surface of the first lens element is R2, a focal length of the imaging lens system is f, half of the maximal field of view is HFOV, and they satisfy the following relations:
0.4<ln(V1/V2)<1.1;
−1.0≦(R1+R2)/(R1−R2)<0.4;
and
1.0 mm<f/tan(HFOV)<7.5 mm.

6 more elements

An imaging lens system, in order from an object side to an image side comprising two non-cemented lens elements with refractive power:

a positive first lens element having a convex object-side surface at a paraxial region thereof and a convex or flat image-side surface at the paraxial region thereof;
and
a negative second lens element having a concave object-side surface at a paraxial region thereof and a concave image-side surface at a paraxial region thereof, and both the object-side and image-side surfaces being aspheric;
wherein, the shape of the image-side surface of the second lens element changes from concave when near an optical axis to convex when away from the optical axis;
wherein an Abbe number of the first lens element is V1, an Abbe number of the second lens element is V2, a curvature radius of the object-side surface of the first lens element is R1, a curvature radius of the image-side surface of the first lens element is R2, the imaging lens system further comprises a stop, an axial distance from the stop to the image-side surface of the second lens element is SD, an axial distance between the object-side surface of the first lens element and the image-side surface of the second lens element is TD, and they satisfy the following relations:
0.4<ln(V1/V2)<1.1;
−1.0≦(R1+R2)/(R1−R2)<0.4;
and
0.9<SD/TD<1.2.

6 more elements

Dependencies are inferred from the claim text.