Lens system

• US 10,564,401 B2
• Filed: 01/18/2019
• Issued: 02/18/2020
• Est. Priority Date: 10/22/2015
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Shinohara, Yoshikazu
• Primary Examiner(s): Alexander, William R
• Assistant Examiner(s): Washington, Tamara Y.
• Application Number:
  US16/252,434
• Publication Number:
  US 20190227284A1
• Time in Patent Office: 396 Days
• Field of Search: 359641, 359648, 359650, 359672-706, 359712-716
• CPC Class Codes: G02B 13/0045 having five or more lenses
• CPC Class Codes: G02B 13/02 Telephoto objectives, i.e. systems of the type + - in which the distance from the front vertex to the image plane is less than the equivalent focal length
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G02B 5/005 Diaphragms for cameras G03B9/02
• CPC Class Codes: G02B 5/208 for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation
• CPC Class Codes: G02B 9/62 having six components only

Abstract

Compact narrow angle lens systems that may be used in small form factor cameras. The lens system may include six lens elements with refractive power, and may provide lower F-numbers while maintaining or improving imaging quality and package size when compared to other compact lens systems. Total track length of the lens system may be 6.5 millimeters or less, for example 5.9 or 6 millimeters. Focal length of the lens system may be 7.0 millimeters or less, for example 6.6 millimeters. The lens system may include an aperture stop located behind the front vertex of the lens system, for example between the first and second lens elements, that effectively moves the ideal principal point of the camera to in front of the front vertex. The lens system may provide a focal ratio of 2.8 or less, for example 2.6 or 2.4.

Claims

1. A lens system, comprising:

six refractive lens elements arranged along an optical axis and configured to refract light from an object field to form an image of a scene at an image plane, wherein the lens elements include, in order along the optical axis 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 having a concave image side surface and a concave object side surface;

a third lens element having a convex image side surface;

a fourth lens element with negative refractive power having a concave image side surface;

a fifth lens element; and

a sixth lens element with positive refractive power having a convex image side surface; and

an aperture stop located behind a front vertex of the lens system;

wherein a total track length (TTL) of the lens system is 6.5 millimeter or less, and wherein a focal ratio of the lens system is 2.8 or less; and

wherein the lens system has effective focal length f and wherein a telephoto ratio (TTL/f ) of the lens system is less than or equal to 1.0.

2. The lens system as recited in claim 1, wherein the third lens element from the object side of the lens system is a positive lens with positive refractive power.

3. The lens system as recited in claim 1, wherein the fifth lens element from the object side of the lens system is a negative lens with negative refractive power.

4. The lens system as recited in claim 1, wherein effective focal length f of the lens system is 7.0 millimeters or less.

5. The lens system as recited in claim 1, wherein the aperture stop is located between the first lens element and the second lens element of the lens system.

6. The lens system as recited in claim 1, wherein effective aperture of the lens system is 2.8 millimeters or less.

7. A camera system, comprising:

a lens system comprising;

six refractive lens elements arranged along an optical axis and configured to refract light from an object field to form an image of a scene at an image plane, wherein the six refractive lens elements include, in order along the optical axis 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 having a concave image side surface and a concave object side surface;

a third lens element having a convex image side surface;

a fourth lens element with negative refractive power having a concave image side surface;

a fifth lens element; and

a sixth lens element with positive refractive power having a convex image side surface; and

an aperture stop located behind a front vertex of the lens system;

wherein a total track length (TTL) of the lens system is 6.5 millimeter or less, and wherein a focal ratio of the lens system is 2.8 or less;

wherein the lens system has effective focal length f , and wherein a telephoto ratio (TTL/f ) of the lens system is less than or equal to 1.0; and

a photosensor configured to capture light projected onto a surface of the photosensor from the lens system.

8. The camera system as recited in claim 7, wherein effective aperture of the lens system is 2.8 millimeters or less.

9. The camera system as recited in claim 7, wherein the third lens element from the object side is a positive lens with positive refractive power.

10. The camera system as recited in claim 7, wherein the fifth lens element from the object side is a negative lens with negative refractive power.

11. The camera system as recited in claim 7, wherein at least one surface of at least one of the six refractive lens elements is aspheric.

12. The camera system as recited in claim 7, wherein at least one of the six refractive lens elements is composed of a first plastic material, and wherein at least one other of the six refractive lens elements is composed of a second plastic material with different optical characteristics than the first plastic material.

13. 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 comprises;

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 proximate to the surface of the photosensor, wherein the lens system comprises;

six refractive lens elements arranged along an optical axis and configured to refract light from an object field to form an image of a scene at an image plane, wherein the lens elements include, in order along the optical axis 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 having a concave image side surface and a concave object side surface;

a third lens element having a convex image side surface;

a fourth lens element with negative refractive power having a concave image side surface;

a fifth lens element; and

a sixth lens element with positive refractive power having a convex image side surface; and

an aperture stop located behind a front vertex of the lens system;

wherein a total track length (TTL) of the lens system is 6.5 millimeter or less, and wherein a focal ratio of the lens system is 2.8 or less; and

wherein the lens system has effective focal length f and wherein a telephoto ratio (TTL/f ) of the lens system is less than or equal to 1.0.

14. The device as recited in claim 13, wherein effective aperture of the lens system is 2.8 millimeters or less.

15. The device as recited in claim 13, wherein the third lens element from the object side is a positive lens with positive refractive power.

16. The device as recited in claim 13, wherein the fifth lens element from the object side is a negative lens with negative refractive power.

17. The device as recited in claim 13, wherein at least one surface of at least one of the six refractive lens elements is aspheric.