US 8,804,253 B2Granted

Image lens system

AssigneeLargan Precision Co., Ltd.

InventorsTsung-Han Tsai, Ming-Ta Chou

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Abstract

This invention provides an image lens system in order from an object side to an image side comprising: a positive first lens element with a convex object-side surface; a negative second lens element; a plastic third lens element with a concave image-side surface, both the object-side and image-side surfaces thereof being aspheric; a positive plastic fourth lens element with a convex object-side surface and a convex image-side surface, both surfaces thereof being aspheric; and a negative plastic fifth lens element with a concave image-side surface, both the object-side and image-side surfaces thereof being aspheric, at least one inflection point is formed on at least one of the two surfaces thereof; wherein there are air distances between each of lens elements. By such arrangement, not only the photosensitivity and total track length of the system can be reduced, but also better image quality can be obtained.

Claims20

Dependent claims

An image lens system comprising, in order from an object side to an image side:

a first lens element with positive refractive power having a convex object-side surface;
a second lens element with negative refractive power;
a plastic third lens element having a concave image-side surface, both the object-side and image-side surfaces thereof being aspheric;
a plastic fourth lens element with positive refractive power having a convex object-side surface and a convex image-side surface, both the object-side and image-side surfaces thereof being aspheric;
and
a plastic fifth lens element with negative refractive power having a concave image-side surface, both the object-side and image-side surfaces thereof being aspheric, at least one inflection point is formed on at least one of the object-side and image-side surfaces thereof;
wherein there are air distances between the first lens element, the second lens element, the third lens element, the fourth lens element and the fifth lens element;
wherein the image lens system comprises a total of five lens elements with refractive power;
wherein a focal length of the image lens system is f, a focal length of the fourth lens element is f4, an axial distance between the third lens element and the fourth lens element is T34, an axial distance between the fourth lens element and the fifth lens element is T45, and they satisfy the following relations:
0<f/f4<0.95;
and
0<T34/T45<2.85.

9 more elements

Dependencies are inferred from the claim text.