Folded camera lens designs

• US 10,571,644 B2
• Filed: 01/19/2019
• Issued: 02/25/2020
• Est. Priority Date: 02/23/2017
• Status: Active Grant

• Current Assignee: Corephotonics Ltd. (Samsung Electronics Co. Ltd.)
• Original Assignee: Corephotonics Ltd. (Samsung Electronics Co. Ltd.)
• Inventors: Shabtay, Gal, Goldenberg, Ephraim, Dror, Michael, Yedid, Itay, Bachar, Gil
• Primary Examiner(s): Alexander, William R
• Assistant Examiner(s): Mebrahtu, Ephrem Z
• Application Number:
  US16/252,608
• Publication Number:
  US 20190170965A1
• Time in Patent Office: 402 Days
• CPC Class Codes: G02B 13/004 having four lenses
• CPC Class Codes: G02B 13/0065 having a beam-folding prism or mirror
• CPC Class Codes: G02B 13/009 having zoom function
• 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 27/0149 characterised by mechanical features G02B27/0176 takes precedence
• CPC Class Codes: G02B 7/021 for more than one lens
• CPC Class Codes: G02B 7/08 adapted to co-operate with a remote control mechanism
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof
• CPC Class Codes: H04N 23/58 Means for changing the camera field of view without moving the camera body, e.g. nutating or panning of optics or image sensors

Abstract

Digital cameras, optical lens modules for such digital cameras and methods for assembling lens elements in such lens modules. In various embodiments, the digital cameras comprise an optical lens module including N≥3 lens elements L_i, each lens element comprising a respective front surface S_2i-1 and a respective rear surface S_2i. In various embodiments the first lens element toward the object side, L₁ and its respective front surfaces S₁ have optical and/or mechanical properties, such as a clear aperture, a clear height and a mechanical height that are larger than respective properties of following lens elements and surfaces. This is done to achieve a camera with large aperture stop, given a lens and/or camera height.

Claims

1. A digital camera, comprising:

a) N lens elements having a symmetry along a first optical axis, wherein N is equal to or greater than 3;

b) an image sensor;

c) an optical path folding element (OPFE) operative to provide a folded optical path from a first optical path to a second optical path; and

d) a barrel with a cavity in which the plurality of lens elements are held, wherein a height of cavity measured along the first optical path is variable along the first optical axis,

wherein the cavity comprises a first portion in which a first lens element L₁ of the N lens elements is located and a second portion in which at least the last lens element L_N of the other lens elements closest to the sensor is located,

wherein a height of the first portion of the cavity H₁ is greater than the height of the second portion of the cavity H₂, so that H₁>

1.1×

H₂,

wherein each lens element of the N lens elements comprises a respective front surface S_2i-1 and a respective rear surface S_2i, the lens element surfaces marked S_k where 1≤

k≤

2N,

wherein each lens element surface S_k has a clear height value CH(S_k), and

wherein clear height value CH(S₁) of surface S₁ is greater than a clear height value of each of surfaces S₂ to S_2N.

2. The digital camera of claim 1, wherein the N lens elements have an axial symmetry.

3. The digital camera of claim 1, wherein the digital camera has a total track length TTL and a focal back length BFL and wherein BFL≥

0.3×

TTL.

4. The digital camera of claim 1, wherein lens element L₁ is made of glass.

5. The digital camera of claim 1, wherein lens element L₁ is made of plastic.

6. The digital camera of claim 1, wherein lens element L₁ is made of plastic for any 2≤

i≤

N.

7. The digital camera of claim 1, wherein the N lens elements form a front aperture lens module.

8. The digital camera of claim 1, wherein at least some of the lens elements have a width W_L greater than their height H_L.

9. The digital camera of claim 1, wherein a height of cavity, measured along an axis orthogonal to the first optical axis, is variable along the first optical axis.

10. The digital camera of claim 1, wherein lens element L₁ has a portion that is not completely surrounded by the cavity and wherein walls of the cavity align a center of lens element L₁ with the first optical axis.

11. The digital camera of claim 8, wherein lens element L_N is located outside the barrel.

12. The digital camera of claim 10, wherein lens element L_N has a portion that is not completely surrounded by the cavity and wherein walls of the cavity align a center of lens element L_N with the first optical axis.

13. The digital camera of claim 10, wherein at least one of an extremity of the walls and an extremity of lens element L₁ is shaped so that the extremity of the walls acts a stop for at least a portion of lens element L₁, thereby aligning a center of lens element L₁ with the first optical axis.

14. The digital camera of claim 12, wherein a first portion of lens element L₁ is located in the cavity between the extremity of the walls and a second portion of lens element L₁ is located outside the barrel and wherein a thickness of the second portion of lens element L₁ along the first optical axis is greater than a thickness of the first portion of lens element L₁ along the first optical axis.

15. The digital camera of claim 12, wherein a cross-section of the extremity of the walls has a stepped shape.

16. The digital camera of claim 12, wherein a cross-section of the extremity of lens element L₁ has a stepped shape.

17. The digital camera of claim 12, wherein a cross-section of the extremity of the walls has a sloping shape.

18. The digital camera of claim 12, wherein the extremity of the walls comprises a chamfer.

19. The digital camera of claim 10, further comprising a cover for covering and protecting lens element L₁.

20. The digital camera of claim 19, wherein the cover has an extreme point beyond lens element L₁.

21. The digital camera of claim 19, wherein the cover blocks light from entering a mechanical part of lens element L₁.

22. The digital camera of claim 1, wherein each lens elements of the N lens elements comprises a respective front surface S_2i-1 and a respective rear surface S_2i, the lens element surfaces marked S_k where 1≤

k≤

2N, wherein each respective lens element surface S_k has a clear aperture value CA(S_k), wherein CA(S₁) is greater than CA(S_k) for 2≤

k≤

2N and wherein CA(S_2N)≤

CA(S₁).

23. The digital camera of claim 22, wherein CA(S₁)<

7 mm.

24. The digital camera of claim 1, wherein CH(S₁)<

7 mm.