Imaging lens system

Patent metadata

Field	Value
Publication number	US-11347030-B2
Application number	US-201815979776-A
Country	US
Kind code	B2
Filing date	May 15, 2018
Priority date	Jun 20, 2017
Publication date	May 31, 2022
Grant date	May 31, 2022

Abstract

Compact lens systems are described that may be used in small form factor cameras. The lens systems may include seven lens elements with refractive power, and may provide low F-numbers with wide field of view while maintaining or improving imaging quality and package size when compared to other compact lens systems. The lens systems may, for example, provide a focal ratio of 1.85 or less, with full field of view of 75 degrees or more. The lens systems may conform to a criterion for compactness TTL/ImageH<1.7, where TTL is the total track length of the lens system, and ImageH is the semi-diagonal image height of the image plane at the photosensor. Lens system parameters and relationships may be selected at least in part to reduce, compensate, or correct for optical aberrations and lens artifacts and effects across the field of view.

First claim

What is claimed is:

1. A lens system, comprising:
a plurality of refractive lens elements arranged along an optical axis of the lens system, wherein the plurality of lens elements includes, in order along the optical axis from an object side to an image side:
a first lens element with positive refractive power;
a second lens element with refractive power;
a third lens element with negative refractive power;
a fourth lens element with positive refractive power;
a fifth lens element with refractive power;
a sixth lens element with positive refractive power; and
a seventh lens element with refractive power;

wherein Abbe number of the sixth lens element (Vd 6 ) satisfies Vd 6 >45;
wherein the lens system satisfies the relationship:
TTL/Image H <1.7,

where TTL is total track length of the lens system, and ImageH is semi-diagonal image height at an image plane of the lens system;
wherein the second lens element has an Abbe number higher than respective Abbe numbers for the third and fifth lens elements;
wherein the lens system satisfies the relationship:
( R 9+ R 10)/( R 9− R 10)<−2,

where R 9 is radius of curvature of an object side surface of the fifth lens element and R 10 is radius of curvature of an image side surface of the fifth lens element; and
wherein an F-number of the lens system is within a range of 1.6 to 1.85.

2. The lens system as recited in claim 1 , wherein the lens system satisfies the relationship:
0.6<( f system /f 12)<1.4,

where f system is effective focal length of the lens system and f 12 is composite focal length of the first and second lens elements.

3. The lens system as recited in claim 1 , wherein the lens system satisfies the relationship:
0.55<| f system /f 3|+| f system /f 5|<1.15,

where f system is effective focal length of the lens system, f 3 is effective focal length of the third lens element, and f 5 is effective focal length of the fifth lens element.

4. The lens system as recited in claim 1 , wherein the lens system satisfies the relationship:
0.8<( Vd 1+ Vd 3)/ Vd 2<3,

where Vd 1 , Vd 2 , and Vd 3 are Abbe numbers of the first, second, and third lens elements, respectively.

5. The lens system as recited in claim 1 , wherein the third lens element has a concave image-side surface in a paraxial region.

6. The lens system as recited in claim 1 , wherein the fifth lens element has a concave object-side surface and a convex image-side surface.

7. The lens system as recited in claim 1 , wherein an object-side surface and an image-side surface of the sixth lens element are aspheric, wherein the sixth lens element has a convex object-side surface in a paraxial region, and wherein the object side surface of the sixth lens element has at least one part being concave in a peripheral region.

8. The lens system as recited in claim 1 , wherein an object-side surface and an image-side surface of the seventh lens element are aspheric, wherein the seventh lens element has a concave image-side surface in a paraxial region, wherein the object-side surface of the seventh lens element has at least one part being concave in a peripheral region, and wherein the image-side surface of the seventh lens element has at least one part being convex in a peripheral region.

9. The lens system as recited in claim 1 , wherein the lens system further includes an aperture stop located between a front vertex of the lens system and the second lens element.

10. The lens system as recited in claim 9 , wherein the lens system further includes at least one secondary stop located between the first lens element and the fifth lens element.

11. The lens system as recited in claim 1 , wherein effective focal length f of the lens system is within a range of 3.4 to 5 mm, and full field of view of the lens system is within a range of 75 to 94 degrees.

12. The lens system as recited in claim 1 , wherein TTL of the lens system is less than 6.8 mm.

13. A camera, comprising:
a photosensor configured to capture light projected onto a surface of the photosensor; and
a lens system configured to refract light from an object field located in front of the camera to form an image of a scene at an image plane at or near the surface of the photosensor, wherein the lens system includes seven refractive lens elements arranged in order along an optical axis from a first lens element having a positive refractive power on an object side of the camera to a seventh lens element on an image side of the camera, including a fourth lens with positive refractive power and a sixth lens element with positive refractive power;
wherein the lens system satisfies the relationship:
TTL/Image H <1.7,

where TTL is total track length of the lens system, and ImageH is semi-diagonal image height at the image plane; and
wherein a second lens element in order along the optical axis has an Abbe number higher than respective Abbe numbers for a third lens element and a fifth lens element in order along the optical axis;
wherein Abbe number of the sixth lens (Vd 6 ) satisfies Vd 6 >45;
wherein the lens system satisfies the relationship:
( R 9+ R 10)/( R 9− R 10)<−2,

where R 9 is radius of curvature of an object side surface of the fifth lens element and R 10 is radius of curvature of an image side surface of the fifth lens element; and
wherein an F-number of the lens system is within a range of 1.6 to 1.85.

14. The camera as recited in claim 13 , wherein the lens system satisfies one or more of the relationships:
0.6<( f system /f 12)<1.4,
0.55<| f system /f 3|+| f system /f 5|<1.15,
( R 9+ R 10)/( R 9− R 10)<−2,

0.8<( Vd 1+ Vd 3)/ Vd 2<3,

where f system is effective focal length of the lens system, f 12 is composite focal length of the first and second lens elements, f 3 is effective focal length of the third lens element, f 5 is effective focal length of the fifth lens element, R 9 is radius of curvature of an object side surface of the fifth lens element, R 10 is radius of curvature of an image side surface of the fifth lens element, and Vd 1 , Vd 2 , and Vd 3 are Abbe numbers of the first, second, and third lens elements, respectively.

15. The camera as recited in claim 13 , wherein effective focal length f of the lens system is within a range of 3.4 to 5 mm, and full field of view of the lens system is within a range of 75 to 94 degrees.

16. The camera as recited in claim 13 , wherein TTL of the lens system is less than 6.8 mm.

17. A device, comprising:
one or more processors;
one or more cameras; and
a memory comprising program instructions executable by at least one of the one or more processors to control operations of the one or more cameras;
wherein at least one of the one or more cameras is a camera comprising:
a photosensor configured to capture light projected onto a surface of the photosensor; and
a lens system configured to refract light from an object field located in front of the camera to form an image of a scene at an image plane at or near the surface of the photosensor, wherein the lens system includes seven refractive lens elements arranged in order along an optical axis from a first lens element having a positive refractive power on an object side of the camera to a seventh lens element on an image side of the camera, including a fourth lens with positive refractive power and a sixth lens element with positive refractive power;
wherein the lens system satisfies the relationship:
TTL/Image H <1.7,

where TTL is total track length of the lens system,

Assignees

• Apple Inc

Inventors

• Yao Yuhong
• Shinohara Yoshikazu
• Liao Lin-Yao

Classifications

• G02B9/64

  having more than six components · CPC title

• G02B13/0045 Primary

  having five or more lenses · CPC title