Lens components

Abstract

The lens assembly includes seven lens elements numbered L1 to L7 from the object side to the imaging side; an optical window; and an image sensor having a sensor diagonal length (SDL), wherein an exemplary lens assembly has a total lens length TTL including the optical window, an effective focal length EFL, and a field of view (FOV), wherein TTL / EFL<1.100, wherein TTL / SDL<0.64, wherein FOV<90 degrees, wherein the normalized thickness standard deviation constant T_STD and the center thickness CT of at least three of the seven lens elements meet T_STD / CT<0.065, wherein the focal length f of the lens element L1 1 Satisfy f 1 / EFL<0.95.

Description

[0001] This application is a divisional application of application number CN 202080004884.1 (PCT application number is PCT / IB2020 / 056923), application date July 22, 2020, and invention name “Low total lens length for large sensor format”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Provisional Patent Application No. 62 / 889,633, filed on August 21, 2019, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0004] Embodiments disclosed herein relate to optical lenses, and more particularly to micro lens assemblies. Background Art

[0005] Digital camera modules are now standard in a variety of host devices. Such host devices include cell phones (smart phones), personal data assistants (PDAs), computers, and the like. Smart phone cameras in particular require a small imaging lens system to achieve high quality imaging and have a small total track length (TTL) relative to the size of the image sensor in such cameras. The size of an image sensor can be expressed in terms of the sensor diagonal (SDL). Summary of the invention

[0006] In various exemplary embodiments, a lens assembly is disclosed that includes: from an object side to an imaging side, seven lens elements numbered L1 to L7, an optical window, and an image sensor having a sensor diagonal length (SDL), wherein the exemplary lens assembly has a total lens length TTL including the optical window, an effective focal length EFL, and a field of view (FOV), wherein TTL / EFL<1.100, wherein TTL / SDL<0.64, wherein FOV<90 degrees, wherein the focal length f of the lens element L1 1 Satisfy f 1 / EFL<0.95.

[0007] In one embodiment, D / 2 is the aperture radius, where for the surface LO of L1 1 , LI 1 and the surface LO of L2 2 , LI 2 , the sign z(r) is positive from z(0.85*D / 2) to z(D / 2), for the surface LO of L4 4 , LI 4 , L5 surface LO 5 , LI5 , L6 surface LO 6 , LI 6 and the surface LO of L7 7 , LI 7 , the sign z(r) is negative from z(0.85*D / 2) to z(D / 2).

[0008] In some embodiments, each element has a clear aperture (CA), wherein the clear aperture of lens element L3 or L4 is the smallest of all clear apertures of the lens assembly.

[0009] In some embodiments, TTL / EFL<1.090.

[0010] In some embodiments, TTL / EFL<1.083.

[0011] In some embodiments, TTL / SDL<0.63.

[0012] In some embodiments, TTL / SDL<0.61.

[0013] In some embodiments, lens element L1 is convex on the object side.

[0014] In some embodiments, starting from lens element L1, the plurality of lens elements have a power-of-one sign sequence of positive-negative-positive-negative-positive-positive-negative.

[0015] In some embodiments, the CT of at least six of the seven lens elements meets CT / TTL<0.07.

[0016] In some embodiments, f 1 / EFL<0.9.

[0017] In some embodiments, f 1 / EFL<0.85;

[0018] In some embodiments, the focal length f of lens element L5 5 Satisfy | 5 / EFL|>4.0.

[0019] In some embodiments, the focal length f of lens element L5 5 Satisfy | 5 / EFL|>6.0.

[0020] In some embodiments, the focal length f of lens element L5 5 Satisfy | 5 / EFL|>8.0.

[0021] In some embodiments, the focal length f of lens element L6 is 6 Satisfy | 6 / EFL|>15.0.

[0022] In some embodiments, the focal length f of lens element L6 is 6 Satisfy | 6 / EFL|>30.0.

[0023] In some embodiments, the focal length f of lens element L6 is 6 Satisfy | 5 / EFL|>45.0.

[0024] In some embodiments, a normalized gap standard deviation constant G_STD of a gap between lens elements L1 and L2 meets G_STD<0.01.

[0025] In some embodiments, a normalized gap standard deviation constant G_STD of a gap between lens elements L1 and L2 meets G_STD<0.007.

[0026] In some embodiments, SDL = 12 mm and FOV < 82.1 degrees BRIEF DESCRIPTION OF THE DRAWINGS

[0027] A number of non-limiting examples of the various embodiments disclosed herein are described with reference to the accompanying drawings listed later in this paragraph. The drawings and description are intended to explain and illustrate the various embodiments disclosed herein and should not be considered limiting in any way. Similar elements in different drawings may be represented by similar numbers. The elements in the drawings are not necessarily drawn to scale.

[0028] Figure 1 An exemplary embodiment of a lens assembly disclosed herein is shown. DETAILED DESCRIPTION

[0029] Figure 1 An embodiment of an optical lens system disclosed herein and numbered 100 is shown. Embodiment 100 includes a plurality of lens elements (here exemplarily seven lens elements numbered L1 to L7) having a common optical axis 102 in order from the object side to the imaging side. The lens also includes three aperture stops labeled S1 and two blocking surfaces S8 and S9. The lens element surfaces are labeled "Si", where S2 labels the object side surface of the first lens element L1 and S18 labels the imaging side of the lens element L7. Lens 100 also includes an optional glass window 104 disposed between surface S18 and an image sensor 106 for image formation of an object. Image sensor 106 has a size characterized by an image sensor diagonal SDL.

[0030] TTL is defined as the1 Distance to the image sensor. Figure 1 Also shown is the back focal length (BFL), which is defined as the distance from the last lens element S 2N The distance from the last surface to the image sensor.

[0031] For convenience in some of the equations and relationships shown below, the lens element surfaces are also marked with “LO i ", on the imaging side surface of lens element number i, mark "LI i ”.

[0032] Surface type

[0033] The surface types are defined in Table 1 and the surface coefficients in Table 2:

[0034] a) Plane: a flat surface with no curvature

[0035] b) Q Type 1 (QT1) surface depression formula:

[0036] (Eq.1)

[0037]

[0038] x=u2

[0039]

[0040] where {z, r} are standard cylindrical polar coordinates, c is the paraxial curvature of the surface, k is the conic parameter, and rnor m Typically half the clear aperture of the surface, and A n are the polynomial coefficients shown in the lens data sheet. The z-axis is directly across the image.

[0041] In this specification, the term "RMO i ” refers to the surface LO i The term "RMI i ” refers to the surface LI i The radius of the aperture.

[0042] In this specification, the term "normal thickness" (NT) is a function of r and is denoted by NT i (r), and is the distance between the two surfaces of a lens element at coordinate r, along the normal vector of the surface closer to the object. Several functions and constants for each normal thickness are defined as:

[0043] For r = 0, NTi (r=0) is defined as the center thickness (CT) of lens element i (CTi)

[0044] The "average thickness" (T_AVGi) constant is given by:

[0045] (Eq2 where k is a discrete variable running from 0 to N, where N is an integer greater than 10 (for this and all other functions and constants below).

[0046] Normalized thickness standard deviation (T_STD i ) constant is given by:

[0047] (Eq3) where k is a discrete variable running from 0 to N, where T_AVG i is defined as (Eq.2).

[0048] In this specification, "gap" or "air gap" refers to the space between consecutive lens components. Several functions and constants for each gap are defined as:

[0049] “Gap i (r)” function (when r=0, “Axis clearance” OA_Gap i ) is defined as the thickness LI i

[0050] Gap i (r) = OA_Gap i +LI i z(r)-LO i+1 z(r), where z(r) is the standard polar coordinate z. i OA_Gap i (r=0) is the air thickness, and r=0 is the air gap.

[0051] Gap Average (G_AVG i ) constant is given by:

[0052] Eq4 where k is a discrete variable running from 0 to N, where N is an integer greater than 10, where Rmin i Is the surface {RMI i , RMO i+1}Minimum aperture radius value;

[0053] The normalized gap standard deviation (G_STDi) constant is given by:

[0054] (Eq.5) And G_AVG iis defined as (Eq.4).

[0055] *Reference wavelength is 587.6 nm (d-line)

[0056]

[0057] *Except for index and Abbe number, the unit is nanometers. HFOV stands for Half Field of View

[0058] Table 1

[0059]

[0060] Table 2

[0061]

[0062] Table 2 (continued)

[0063] Table 3 below summarizes the design features and parameters present in the above examples. These characteristics contribute to the goal of a small lens (i.e., small TTL) with large image height (i.e., large SDL) and small F number (F#):

[0064] "AA":AA 1 ≡TTL / EFL<1.100,AA 2 ≡TTL / EFL<1.090,AA 3 ≡

[0065] TTL / EFL<1.083;

[0066] "BB":BB 1 ≡TTL / SDL<0.64,BB 2 ≡TTL / SDL<0.63,BB 3 ≡TTL /

[0067] SDL < 0.61;

[0068] "CC": Lens 1 is convex on the target side;

[0069] "DD": CA of lens 3 or 4 is the smallest among all components;

[0070] "EE": power symbol sequence: +-+-++-;

[0071] "FF": The center thickness (CT) of at least six of the seven lens components meets the following criteria: FF 1 =

[0072] CT / TTL<0.07;

[0073] “II” for surface LO1 , LI 1 , LO 2 , LI 2 , the sign z(r) is positive from z(0.85*D / 2) to z(D / 2), for the surface LO 4 , LI 4 , LO 5 , LI 5 , LO 6 , LI 6 , LO 7 , LI 7 , the sign z(r) is negative from z(0.85*D / 2) to z(D / 2);

[0074] "JJ": JJ 1 ≡f 1 / EFL<0.95,JJ 2 ≡f 1 / EFL<0.9,JJ 3 ≡f 1 / EFL<0.85;

[0075] "KK": KK 1 ≡|f 5 / EFL|>4.0,KK 2 ≡|f 5 / EFL|>6.0,KK 3 ≡|f 5 / EFL|>8.0;

[0076] "LL":LL 1 ≡|f 6 / EFL|>15.0,LL 2 ≡|f 6 / EFL|>30.0,LL 2 ≡|f 6 / EFL|>45.0;

[0077] "MM": The gap between lenses 1 and 2 meets: MM 2 ≡G_STD<0.01, and

[0078] MM 3 ≡G_STD<0.007;

[0079] “NN”: For a given SDL (12 mm), 0 ≤ FOV < 82.1 degrees.

[0080] Table 3

[0081] In summary, the various lens assembly embodiments disclosed herein have or satisfy the different design features and parameters listed in the above table.

[0082] Although the disclosure describes a limited number of embodiments, it should be understood that many variations, modifications and other applications of these embodiments are possible. In general, the disclosure should be understood not to be limited to the specific embodiments described herein, but only to the scope of the appended claims.

Claims

1. A lens assembly, comprising: From a target side to an imaging side, The seven lens elements are numbered L1 to L7; an optical window; and an image sensor having a sensor diagonal length SDL, The lens assembly has a total lens length TTL including the optical window, an effective focal length EFL, and a field of view FOV less than 90 degrees, wherein TTL / EFL<1.100, wherein TTL / SDL<0.64, wherein the focal length f1 of the lens element L1 satisfies f1 / EFL<0.95, wherein the lens element L1 is convex on the target side, wherein starting from the lens element L1, the seven lens elements have a light focality symbol sequence of positive-negative-positive-negative-positive-positive-negative, wherein the center thickness CT of at least six of the seven lens elements satisfies CT / TTL<0.

07.

2. A lens assembly as described in claim 1, wherein each lens element has a clear aperture CA, wherein the clear aperture of lens element L3 or L4 is the smallest among all clear apertures of the lens assembly.

3. The lens assembly of claim 1, wherein TTL / EFL<1.

090.

4. The lens assembly of claim 1, wherein TTL / EFL<1.

083.

5. The lens assembly of claim 1, wherein TTL / SDL<0.

63.

6. The lens assembly of claim 1, wherein TTL / SDL<0.

61.

7. The lens assembly of claim 1, wherein f1 / EFL<0.

9.

8. The lens assembly of claim 1, wherein f1 / EFL<0.

85.

9. The lens assembly of claim 1, wherein the focal length f5 of the lens element L5 satisfies |f5 / EFL|>4.

0.

10. The lens assembly of claim 1, wherein a focal length f5 of lens element L5 satisfies |f5 / EFL|>6.

0.

11. The lens assembly of claim 1, wherein a focal length f5 of lens element L5 satisfies |f5 / EFL|>8.

0.

12. The lens assembly of claim 1 , wherein focal length f6 of lens element L6 satisfies |f6 / EFL| >15.

0.

13. The lens assembly of claim 1, wherein focal length f6 of lens element L6 satisfies |f6 / EFL|>30.

0.

14. The lens assembly of claim 1, wherein focal length f6 of lens element L6 satisfies |f6 / EFL|>45.

0.

15. The lens assembly of claim 1, wherein a normalized gap standard deviation constant G_STD of a gap between the lens elements L1 and L2 complies with G_STD<0.

007.

16. The lens assembly of claim 1, wherein SDL = 12 mm, wherein FOV < 82.1 degrees.

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