MINIATURE TELEPHOTO LENS ASSEMBLY

• US 20160085056A1
• Filed: 11/04/2015
• Published: 03/24/2016
• Est. Priority Date: 07/04/2013
• Status: Active Grant

• Current Assignee: Corephotonics Ltd. (Samsung Electronics Co. Ltd.)
• Original Assignee: Corephotonics Ltd. (Samsung Electronics Co. Ltd.)
• Inventors: Goldenberg, Ephraim, Shabtay, Gal, Dror, Michael
• Granted Patent: US 9,402,032 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G02B 1/041 Lenses
• CPC Class Codes: G02B 13/00 Optical objectives specially designed for the purposes specified below with variable magnification in general G02B15/00
• CPC Class Codes: G02B 13/002 having at least one aspherical surface
• CPC Class Codes: G02B 13/004 having four lenses
• CPC Class Codes: G02B 13/0045 having five or more lenses
• 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 13/18 with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration G02B13/002 takes precedence
• CPC Class Codes: G02B 27/0025 for optical correction, e.g. distorsion, aberration
• CPC Class Codes: G02B 27/646 compensating for small deviations, e.g. due to vibration or shake movement of one or more optical elements for control of motion blur in cameras, projectors or printers G03B2205/0007; image stabilisation in cameras peculiar to the presence or use of an electronic image sensor H04N23/68
• CPC Class Codes: G02B 5/005 Diaphragms for cameras G03B9/02
• CPC Class Codes: G02B 9/00 Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - G02B15/00 takes precedence
• CPC Class Codes: G02B 9/12 having three components only
• CPC Class Codes: G02B 9/60 having five components only
• CPC Class Codes: G02B 9/62 having six components only
• CPC Class Codes: G02B 9/64 having more than six components
• CPC Class Codes: H04N 2101/00 Still video cameras
• CPC Class Codes: H04N 2201/00 Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
• CPC Class Codes: H04N 23/16 Optical arrangements associated therewith, e.g. for beam-splitting or for colour correction
• CPC Class Codes: H04N 23/45 for generating image signals from two or more image sensors being of different type or operating in different modes, e.g. with a CMOS sensor for moving images in combination with a charge-coupled device [CCD] for still images
• CPC Class Codes: H04N 23/57 : Mechanical or electrical details of cameras or camera modules specially adapted for being embedded in other devices
• CPC Class Codes: H04N 23/69 : Control of means for changing angle of the field of view, e.g. optical zoom objectives or electronic zooming
• CPC Class Codes: Y10T 29/4913 : Assembling to base an electrical component, e.g., capacitor, etc.

Abstract

An optical lens assembly includes five lens elements and provides a TTL/EFL<1.0. In an embodiment, the focal length of the first lens element f1<TTL/2, an air gap between first and second lens elements is smaller than half the second lens element thickness, an air gap between the third and fourth lens elements is greater than TTL/5 and an air gap between the fourth and fifth lens elements is smaller than about 1.5 times the fifth lens element thickness. All lens elements may be aspheric.

Claims

1. A lens assembly, comprising:

a plurality of refractive lens elements arranged along an optical axis, wherein at least one surface of at least one of the plurality of lens elements is aspheric, wherein the lens assembly has an effective focal length (EFL), and wherein the lens assembly has a total track length (TTL) of 6.5 millimeters or less and a ratio TTL/EFL of less than 1.0.

2. The lens assembly of claim 1, wherein the plurality of lens elements comprises, in order from an object side to an image side, a first lens element with positive refractive power, a second lens element with negative refractive power, a third lens element with negative refractive power, and a fourth element, wherein the third and fourth lens elements are separated by an air gap which is greater than TTL/5.

3. The lens assembly of claim 2, wherein the plurality of lens elements further includes a fifth lens element, wherein one of the fourth and the fifth lens elements has a positive refractive power and the other of the fourth and fifth lens elements has a negative refractive power.

4. The lens assembly of claim 3, wherein the fourth lens element and the fifth lens element are separated by a second air gap which is smaller than TTL/20.

5. The lens assembly of claim 4, wherein a focal length f1 of the first lens element is smaller than TTL/2.

6. The lens assembly of claim 5, wherein a lens assembly F # is smaller than 2.9.

7. The lens assembly of claim 6, wherein the first lens element has an Abbe number greater than 50 and the second lens element has an Abbe number smaller than 30.

8. The lens assembly of claim 7, wherein one of the fourth and fifth lens elements that has a positive refractive power is characterized by an Abbe number smaller than 30 and wherein the other of the fourth and fifth lens elements that has a negative refractive power is characterized by an Abbe number greater than 50, thereby adding compensation for chromatic aberrations and assisting in bringing all fields focal points to an image plane.

9. The lens assembly of claim 8, wherein the first lens element has a convex object-side surface and a convex or concave image-side surface and wherein the second lens element is a meniscus lens having a convex object-side surface.

10. The lens assembly of claim 9, wherein the focal length f1, a focal length f2 of the second lens element and a focal length f3 of the third lens element fulfill the condition 1.2×

|f3|>

|f2|>

1.5×

f1.

11. The lens assembly of claim 8, wherein the third, fourth and fifth lens element are made of plastic.

12. The lens assembly of claim 8, wherein all the lens elements are made of plastic.

13. The lens assembly of claim 12, wherein the TTL is 6.0 millimeters or less.

23. The lens assembly of claim 1, wherein the plurality of lens elements comprises, in order from an object side to an image side, a first lens element with positive refractive power and a second lens element with negative refractive power, wherein a focal length fl of the first lens element is smaller than TTL/2.

24. The lens assembly of claim 23, wherein the first lens element has an Abbe number greater than 50 and the second lens element has an Abbe number smaller than 30.

25. The lens assembly of claim 24, wherein the first lens element has a convex object-side surface and a convex or concave image-side surface and wherein the second lens element is a meniscus lens having a convex object-side surface.

26. The lens assembly of claim 25, wherein a lens assembly F # is smaller than 2.9.

27. The lens assembly of claim 26, wherein the plurality of lens elements further comprises a third lens element with negative refractive power, a fourth lens element and a fifth lens element, wherein one of the fourth and fifth lens elements has a positive refractive power and the other of the fourth and the fifth lens elements has a negative refractive power.

28. The lens assembly of claim 27, wherein one of the fourth and fifth lens elements that has a positive refractive power is characterized by an Abbe number smaller than 30 and wherein the other lens element of the fourth and fifth lens elements that has a negative refractive power is characterized by an Abbe number greater than 50, thereby adding compensation for chromatic aberrations and assisting in bringing all fields focal points to an image plane.

29. The lens assembly of claim 27, wherein the third, fourth and fifth lens element are made of plastic, and wherein the fourth and fifth lens elements are separated by a second air gap which is smaller than TTL/20.

30. The lens assembly of claim 28, wherein the focal length f1, a focal length f2 of the second lens element and a focal length f3 of the third lens element fulfill the condition 1.2×

|f3|>

|f2|>

1.5×

f1.

14-22. -22. (canceled)

31. A lens assembly having a total track lens (TTL) smaller than an effective focal lens (EFL) thereof and comprising:

a plurality of lens elements made of at least two different polymer materials having different Abbe numbers and including, in order from an object plane to an image plane along an optical axis of the lens assembly, a first lens element having positive optical power and a pair of second and third lenses having each a negative optical power, the combination of the first, second and third lens elements providing the lens assembly with a ratio TTL/EFL<

1,wherein the second and third lens elements are each made of a different one of the at least two polymer materials having a different Abbe number to reduce chromatic aberrations of the lens assembly, the plurality of lens elements further including a combination of fourth and fifth lens elements configured to assist in bringing all fields focal points to the image plane, wherein the third and fourth lens elements are separated by an air gap which is greater than TTL/5, and wherein the fourth and fifth lens elements are each made of a different one of the at least two polymer materials having a different Abbe number to further reduce chromatic aberrations of the lens assembly.