Fixed-focus lens

Patent metadata

Field	Value
Publication number	US-9261670-B2
Application number	US-201314133642-A
Country	US
Kind code	B2
Filing date	Dec 19, 2013
Priority date	Aug 28, 2013
Publication date	Feb 16, 2016
Grant date	Feb 16, 2016

Abstract

A fixed-focus lens including a first lens group and a second lens group is provided. The first lens group having a negative refractive power includes a first lens, a second lens and a third lens arranged in sequence from an object side to an image side, in which refractive powers of the first, second and third lenses are negative, negative and positive in sequence. The second lens group having a positive refractive power is located between the first lens group and the image side, and the second lens group includes a fourth lens, a fifth lens and a sixth lens arranged in sequence from the object side to the image side, in which refractive powers of the fourth, fifth and sixth lenses are positive, negative and positive in sequence. The first, second, third, fourth, fifth and sixth lenses are separated from each other.

First claim

What is claimed is:

1. A fixed-focus lens, comprising:
a first lens group having a negative refractive power, the first lens group comprising a first lens, a second lens and a third lens arranged in sequence from an object side to an image side, and refractive powers of the first lens, the second lens and the third lens being negative, negative and positive in sequence; and
a second lens group having a positive refractive power, disposed between the first lens group and the image side, the second lens group comprising a fourth lens, a fifth lens and a sixth lens arranged in sequence from the object side to the image side, and refractive powers of the fourth lens, the fifth lens and the sixth lens being positive, negative and positive in sequence, wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are separated from each other, and an Abbe number of the fourth lens is greater than 70.

2. The fixed-focus lens as recited in claim 1 , wherein none of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens is a cemented lens, and a double cemented lens is not formed by any two of above.

3. The fixed-focus lens as recited in claim 1 , wherein the fixed-focus lens satisfies 0.01<|f 5 /F+f 6 /F|<0.2, wherein f 5 is an effective focal length of the fifth lens, f 6 is an effective focal length of the sixth lens and F is an effective focal length of the fixed-focus lens.

4. The fixed-focus lens as recited in claim 1 , wherein a material of at least one among the first lens, the second lens and the third lens is plastic and a material of the rest is glass; and a material of at least one among the fourth lens, the fifth lens and the sixth lens is plastic and a material of the rest is glass.

5. The fixed-focus lens as recited in claim 1 , wherein a material of the fourth lens is glass.

6. The fixed-focus lens as recited in claim 5 , wherein an Abbe number of the fourth lens is greater than 75.

7. The fixed-focus lens as recited in claim 1 , wherein the first lens, the second lens, and the third lens comprise more than one aspheric lens, and the fourth lens, the fifth lens and the sixth lens comprise more than two aspheric lenses.

8. The fixed-focus lens as recited in claim 1 , wherein the fixed-focus lens satisfies 6<L/H<8, wherein L is a distance from a surface of the first lens facing the object side to the image side on an optical axis of the fixed-focus lens, and H is a maximum imaging height of the fixed-focus lens.

9. The fixed-focus lens as recited in claim 1 , further comprising an aperture stop disposed between the first lens group and the second lens group.

10. The fixed-focus lens as recited in claim 1 , wherein the first lens is a convex-concave lens with a convex surface facing the object side, the second lens is a plane-concave lens with a concave surface facing the image side, the third lens is a concave-convex lens with a concave surface facing the object side, the fourth lens and the sixth lens are respectively biconvex lenses, and the fifth lens is a biconcave lens.

11. A fixed-focus lens, comprising:
a first lens group having a negative refractive power, the first lens group comprising a first lens, a second lens and a third lens arranged in sequence from an object side to an image side; and
a second lens group having a positive refractive power, disposed between the first lens group and the image side, the second lens group comprising a fourth lens, a fifth lens and a sixth lens arranged in sequence from the object side to the image side, wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are separated from each other, and among all the lenses in the second lens group, only the fourth lens has an Abbe number greater than 70.

12. The fixed-focus lens as recited in claim 11 , wherein none of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens is a cemented lens, and a double cemented lens is not formed by any two of above.

13. The fixed-focus lens as recited in claim 11 , wherein the fixed-focus lens satisfies 0.01<|f5/F+f6/F | <0.2, wherein f5 is an effective focal length of the fifth lens, f6 is an effective focal length of the sixth lens and F is an effective focal length of the fixed-focus lens.

14. The fixed-focus lens as recited in claim 11 , wherein a material of at least one among the first lens, the second lens and the third lens is plastic and a material of the rest is glass; and a material of at least one among the fourth lens, the fifth lens and the sixth lens is plastic and a material of the rest is glass.

15. The fixed-focus lens as recited in claim 11 , wherein a material of the fourth lens is glass.

16. The fixed-focus lens as recited in claim 15 , wherein the Abbe number of the fourth lens is greater than 75.

17. The fixed-focus lens as recited in claim 11 , wherein the first lens, the second lens, and the third lens comprise more than one aspheric lens, and the fourth lens, the fifth lens and the sixth lens comprise more than two aspheric lenses.

18. The fixed-focus lens as recited in claim 11 , wherein the fixed-focus lens satisfies 6<L/H<8,wherein L is a distance from a surface of the first lens facing the object side to the image side on an optical axis of the fixed-focus lens, and H is a maximum imaging height of the fixed-focus lens.

19. The fixed-focus lens as recited in claim 11 , further comprising an aperture stop disposed between the first lens group and the second lens group.

20. The fixed-focus lens as recited in claim 11 , wherein the first lens is a convex-concave lens with a convex surface facing the object side, the second lens is a plane-concave lens with a concave surface facing the image side, the third lens is a concave-convex lens with a concave surface facing the object side, the fourth lens and the sixth lens are respectively biconvex lenses, and the fifth lens is a biconcave lens.

Assignees

• Lai Sheng-Tang
• Wang Kuo-Chuan
• Young Optics Inc

Inventors

• Lai Sheng-Tang
• Wang Kuo-Chuan

Classifications

• G02B13/04 Primary

  Reversed telephoto objectives · CPC title

• G02B15/177 Primary

  having a negative front lens or group of lenses · CPC title

• G02B9/62

  having six components only · CPC title

• G02B13/18

  with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)} · CPC title

• G02B9/10 Primary

  one + and one - component · CPC title