TWI853411B - Folded camera lens designs - Google Patents

Abstract

Folded lens modules and assemblies characterized by low height and large entrance pupil (clear aperture), designed for folded cameras in consumer electronics and specifically in mobile phones. In some embodiments, a folded lens assembly comprises a plurality of lens elements that include, in order for an object side to an image side, a first lens element L1 with a clear aperture CA(S1) and a second lens element L2 with a clear aperture CA(S3), wherein CA(S1)/CA(S3) ＞ 1.2 and wherein the lens assembly has a ratio between an image sensor diagonal length SDL and a clear aperture of a last lens element surface CA(S2N), SDL/CA(S2N) ＞ 1.5.

Description

Folding camera lens design

The subject matter of this disclosure generally relates to the field of digital cameras.

Dual-aperture zoom cameras (also called "dual cameras") are known in which one camera (also called "sub-camera") has a wide field of view ("wide-angle sub-camera") and the other has a narrow field of view ("telephoto sub-camera").

International patent publication WO 2016/024192, which is hereby incorporated by reference, discloses a "folding camera module" (also referred to as a "folding camera") that reduces the height of a portable camera. In order to tilt the light propagation direction from perpendicular to the back surface of the smartphone to parallel to the back surface of the smartphone, an optical diameter folding element (also referred to as "OPFE"), such as a prism or a mirror (also referred to as a "reflective element" herein), is added to the folding camera. If the folding camera is part of a dual-aperture camera, a folded aperture is provided through a lens assembly (e.g., a telephoto lens). Such a camera is referred to herein as a "folding lens dual aperture camera". Typically the camera may be included in a multi-aperture camera, for example together with two "non-folding (upright)" camera modules in a tri-aperture camera.

The small height of a folding camera is very important for making a host device containing it (such as a smartphone, tablet, laptop or smart TV) as thin and light as possible. Industrial design often limits the height of the camera. In contrast, increasing the aperture of the lens leads to an increase in the amount of light reaching the image sensor and improves the optical properties of the camera.

Therefore, it is desirable and beneficial to provide a folding camera that provides a maximum lens diameter for a given camera height and/or for a lens module height.

In exemplary embodiments, a high optical performance lens (or "lens assembly") is provided that has a large front clear aperture (CA), a large first surface clear aperture, and all other lens elements of relatively small clear apertures. The lens elements are listed in order from an object side (first lens element L1) to an image side (last lens element L2). In each embodiment, the last lens element clear aperture is less than the diagonal length of an image sensor of the lens contained in a digital camera (also referred to herein as the "sensor diagonal length" or "SDL"). In the following tables, all dimensions are indicated in millimeters. All terms and abbreviations as known in the art have their usual meanings.

In some embodiments, a lens assembly of a folding camera is provided, comprising: a plurality of lens elements, in order from an object side to an image side, comprising a first lens element L1 having a clear aperture CA(S1) and a second lens element L2 having a clear aperture CA(S3), wherein CA(S1)/CA(S3)>1.2 and wherein the lens assembly has a ratio between an image sensor diagonal length SDL and a clear aperture CA(S2N) of a surface of a last lens element, SDL/CA(S2N)>1.5.

In some embodiments, the first lens assembly has positive refractive power and the second lens assembly has negative refractive power, and wherein the plurality of lens assemblies further include a third lens assembly having positive refractive power and a fourth lens assembly having negative refractive power.

In some embodiments, the first lens assembly has positive refractive power and the second lens assembly has negative refractive power, and wherein the plurality of lens assemblies further include a third lens assembly having positive refractive power and a fourth lens assembly having positive refractive power.

In some embodiments, the first lens assembly has positive refractive power and the second lens assembly has negative refractive power, and wherein the plurality of lens assemblies further include a third lens assembly having negative refractive power and a fourth lens assembly having positive refractive power.

In some embodiments, the plurality of lens assemblies further include a fifth lens assembly having negative refractive power.

In some embodiments, the lens assembly has a total track length (TTL) and a back focal length (BFL) and a ratio BFL/TTL>0.35.

In some embodiments, an optical window is positioned within a path defining the BFL and the TTL.

In some embodiments, a lens assembly of a folding camera is provided, comprising: N lens elements, in order from an object side to an image side, including a first lens element L1 having a clear aperture CA(S1), wherein all clear apertures of all other lens elements L2 to LN of the N lens elements are no greater than CA(S1), wherein the folding camera includes an image sensor having a sensor diagonal length SDL, and wherein CA(S1)＜SDL＜1.5xCA(S1).

In the following detailed description, many specific details are set forth to provide a thorough understanding. However, those skilled in the art will appreciate that the subject matter of the present disclosure can be practiced without these specific details. In other cases, well-known methods are not described in detail to avoid obscuring the subject matter of the present disclosure.

It should be understood that, for clarity, certain features of the subject matter of the present disclosure described in the context of individual embodiments may also be provided in combination in a single embodiment. Conversely, for brevity, various features of the subject matter of the present disclosure described in the context of a single embodiment may also be provided individually or in any suitable subcombination.

The term "processing unit" disclosed herein should be broadly interpreted to include any type of electronic device having data processing circuitry, including, for example, a computer processing device (e.g., a digital signal processor (DSP), a microcontroller, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), etc.) operably connected to a computer memory capable of performing various data processing operations.

In addition, for the sake of clarity, the term "substantially" is used herein to imply the possibility that a numerical value may vary within an acceptable range. According to one example, the term "substantially" used herein should be interpreted as implying a possible variation of up to 10% above or below any specified numerical value. According to another example, the term "substantially" used herein should be interpreted as implying a possible variation of up to 5% above or below any specified numerical value. According to another example, the term "substantially" used herein should be interpreted as implying a possible variation of up to 2.5% above or below any specified numerical value.

1A and 1B illustrate a digital folding camera 100 that may operate as, for example, a telephoto camera. The digital camera 100 includes a first reflective element (e.g., a mirror or prism, sometimes also referred to as an "optical path folding element" (OPFE)) 101, multiple lens elements (not shown in this figure, but visible, for example, in FIGS. 2A and 2B), and an image sensor 104. The lens element (also lens barrel, the optical lens module) may have an axial symmetry along a first optical axis 103. At least some of the optical elements may be maintained by a structure referred to as a "lens barrel" 102. An optical lens module includes the lens element and the lens barrel. The barrel may have a longitudinal symmetry along the optical axis 103. In FIGS. 1A to 1D , the cross section of the barrel is circular. However, this is not mandatory and other shapes may be used.

The path of the optical line from an object (not shown) to an image sensor 104 defines an optical path (see optical paths 105 and 106, which represent portions of the optical path.)

The optical path folding element 101 may be a prism or a mirror. As shown in FIG. 1A , the optical path folding element 101 may be a mirror tilted relative to the optical axis 103. In other cases (not shown, for example, see PCT/IB2017/052383), the optical path folding element 101 may be a prism having a back surface that is tilted relative to the optical axis 103. The optical path folding element folds the optical path from a first optical path 105 to a second optical path 106. The optical path 106 is substantially parallel to the optical axis 103. The optical path is therefore referred to as a "folded optical path" (indicated by optical paths 105 and 106) and camera 100 is referred to as a "folded camera."

In particular, in some examples, the optical path folding element 101 can be substantially tilted 450 relative to the optical axis 103. In FIG. 1A, the optical path folding element 101 is also substantially tilted 450 relative to the optical path 105.

In some known examples, the image sensor 104 is located in an X-Y plane substantially perpendicular to the optical axis 103. However, this is not a limitation and the image sensor 104 may have a different orientation. For example, as described in WO 2016/024192, the image sensor 104 may be in the X-Z plane. In this case, an additional optical path folding element may be used to reflect the optical line toward the image sensor 104.

According to some embodiments, the image sensor 104 has a rectangular shape. According to some embodiments, the image sensor 104 has a circular shape. However, these examples are not limiting.

In various examples, the camera 100 may be mounted on a substrate 109, such as a printed circuit board, as is known in the art.

Two sub-cameras, such as a wide-angle sub-camera 130 and a telephoto sub-camera 100 may be included in a digital camera 170 (also referred to as a dual-camera or dual-aperture camera). A possible configuration is described with reference to FIGS. 1C and 1D. In this example, the telephoto sub-camera 100 is described with reference to FIGS. 1A and 1B according to the camera. Therefore, the parts of the telephoto sub-camera 100 as in FIGS. 1A and 1B have the same reference numbers and are not described again.

The wide-angle sub-camera 130 may include an aperture 132 (indicating the object side of the camera) and an optical lens module 133 (or "wide-angle lens module") having a symmetry (and optical) axis 134 in the Y direction, and a wide-angle image sensor 135. The wide-angle lens module is configured to provide a wide-angle image. The wide-angle sub-camera has a wide field of view (FOVW) and the telephoto sub-camera has a telephoto field of view (FOVT) that is narrower than the wide field of view. In particular, in some examples, multiple wide-angle sub-cameras and/or multiple telephoto sub-cameras may be combined and operated in a single digital camera.

According to one example, the wide angle image sensor 135 is located in the X-Z plane, whereas the image sensor 104 (in this example a telephoto image sensor) is located in an X-Y plane substantially perpendicular to the optical axis 130.

In the example of Figures 1A to 1D, the camera 100 may also include (or otherwise be operably connected to) a processing device that includes one or more suitably configured processors (not shown) that perform various processing operations, such as processing the telephoto image and the wide-angle image into a fused output image.

The processing unit may include hardware (HW) and software (SW) dedicated to digital camera operations. Alternatively, a processor of an electronic device installed in the camera (e.g., its local central processing unit) may be adapted to perform various processing operations associated with the digital camera (including, but not limited to, processing the telephoto image and the wide-angle image into an output image).

Attention is now directed to FIGS. 2A and 2B, which show schematic diagrams of lens modules according to some examples of the presently disclosed subject matter, with lens elements shown in optical lines. Lens module 200 is shown without a lens barrel. FIG. 2A shows optical line tracing of lens module 200, while FIG. 2B shows only the lens element for greater clarity. In addition, both figures show an image sensor 202 and an optical element 205.

The lens module 200 includes N lens elements Li (where "i" is an integer between 1 and N). L1 is the lens element closest to the object side, and LN is the lens element closest to the image side, that is, the side where the image sensor is located. All lenses and lens elements disclosed herein maintain this order. Lens element Li can be used, for example, as a lens element of the camera 100 shown in Figures 1A and 1B or as a lens element of the telephoto sub-camera 100 in Figures 1C and 1D. As shown, the N lens elements are axially symmetric along the optical axis 103.

In the example of Figures 2A and 2B, N is equal to four. In the example of Figures 6-12, N is equal to 5, however this is not a limitation and a different number of lens elements may be used. For example, N may be equal to 3, 6 or 7.

In the example of Figures 2A and 2B, some of the surfaces of the lens element are convex and some are concave. However, the illustrations of Figures 2A and 2B are not limiting, and depending on various factors such as the application, the desired optical power, etc., a different combination of convex and/or concave surfaces may be used.

The optical rays (after their reflection by a reflective element, such as the optical path folding element 101) pass through the lens element Li and form an image on an image sensor 202. In the example of FIGS. 2A and 2B, the optical rays pass through an optical element 205 (comprising a front surface 205a and a rear surface 205b, and may be, for example, a cut-off filter) before irradiating the image sensor 202, and the optical element 205 is also referred to as an "optical window" or simply "window". However, this is not a limitation, and in some examples, the optical element 205 is not present. The optical element 205 may be, for example, an infrared (IR) filter, and/or a glass image sensor dust cover.

Each lens element Li includes a respective front surface S2i-1 (the index "2i-1" is the number of the front surface) and a respective back surface S2i (the index "2i" is the number of the back surface), where "i" is an integer between 1 and N. This numbering convention is used throughout the description. Alternatively, as in this description, lens surfaces are labeled "Sk", with k ranging from 1 to 2N. In some cases the front surface and the back surface can be aspherical. However, this is not a limitation.

As used herein, the term "front surface" of each lens element refers to the surface of a lens element located near the entrance of the camera (camera object side), and the term "back surface" refers to the surface of a lens element located near the image sensor (camera image side).

As shown below, a net height value CH(Sk) of 1≤k≤2N can be defined for each surface Sk, and a clear aperture CA(Sk) of 1≤k≤2N can be defined for each surface Sk. CA(Sk) and CH(Sk) define the optical properties of each surface Sk of each lens element.

As shown in Figures 3A, 3B and 4, each optical ray passing through a surface Sk (for 1≤k≤2N) strikes this surface at an impact point IP. The optical ray enters the lens module 200 from surface S1 and passes through surfaces S2 to S2N in succession. Some optical rays may strike any surface Sk but cannot/will not reach the image sensor 202. For a given surface Sk, only optical rays that can form an image on the image sensor 202 are considered to form the multiple impact points IP obtained. CH(Sk) is defined as the distance between two closest possible parallel lines (see lines 400 and 401 in FIG. 4 located on a plane P orthogonal to the optical axis of the lens element (in the illustrations of FIGS. 3A and 3B , plane P is parallel to plane X-Y and orthogonal to optical axis 103), resulting in the orthogonal projection IPorth of all impact points IP on plane P being located between the two parallel lines. Therefore, CH(Sk) can be defined for each surface Sk (front and back surfaces, 1≤k≤2N).

The definition of CH(Sk) does not depend on the object currently being imaged, since it refers to the optical rays that "can" form an image on the image sensor. Thus, even if the object currently being imaged is located in a black background that does not generate light, the definition does not refer to this black background, since it refers to any optical rays that "can" reach the image sensor to form an image (e.g. optical rays emitted by a background that will emit light, as opposed to a black background).

For example, Fig. 3A illustrates the orthogonal projections IPorth,1, IPorth,2 of two impact points IP1 and IP2 on a plane P orthogonal to the optical axis 103. For example, as shown in Fig. 3A, the surface Sk is convex.

Fig. 3B illustrates the orthogonal projections IPorth,3, IPorth,4 of two impact points IP3 and IP4 on the plane P. For example, in this illustration of Fig. 3B, the surface Sk is concave.

In FIG. 4 , the orthogonal projection IPorth of all impact points IP of a surface Sk on plane P lies between parallel lines 400 and 401. Therefore, CH(Sk) is the distance between lines 400 and 401.

Attention is now directed to Fig. 5. In accordance with the presently disclosed subject matter, for each given surface Sk (for 1≤k≤2N) a clear aperture CA(Sk) is defined as the diameter of a circle, where the circle is the smallest possible circle that lies in a plane P orthogonal to the optical axis 103 and that surrounds all orthogonal projections IPorth of all impact points on plane P. As noted above, with respect to CH(Sk), note that this definition of CA(Sk) also does not depend on the object currently being imaged.

As shown in FIG. 5 , the orthogonal projection IPorth of the delimiting line of all impact points IP on plane P is a circle 500. The diameter of the circle 500 is defined as CA (Sk).

The following table gives detailed optical data and surface data of ten lens (or lens assembly) examples (embodiments) numbered Ex1, Ex2, ... Ex 10. The ten lens assembly embodiments Ex1 to Ex10 are also shown in Figures 2, 6, 7, 8, 9, 10, 11, 12, 13 and 14, respectively.

Characteristic Description Table

Tables 1, 4, 7, 10, 13, 16, 19, 22, 25 and 28 provide a summary of the characteristics of each lens in Examples 1-10, respectively. For each lens, the following parameters are described: - Effective focal length (EFL), in millimeters (mm). - Total track length (TTL), in millimeters, defined as the distance from the first surface S1 of the first lens element to the image sensor. In some embodiments, an optical window is positioned within the total track length and is included in the total track length. - f number f/#, (unitless number). - Image sensor diagonal length (SDL), in millimeters. - Back focal length (BFL), in millimeters, the distance from the last surface of the last lens element S2N to the image sensor. In some embodiments, an optical window is positioned in the back focal length and is included in the back focal length. - The ratio between the total track length and the back focal length, TTL/EFL. - The ratio between the back focal length and the effective focal length, BFL/EFL. - The ratio between the clear aperture (CA) of the first surface S1 of the first lens element and the clear aperture of the first surface S3 of the second lens element CA(S1)/CA(S3). - The focal length of each lens, fi.

Surface parameter table

Tables 2, 5, 8, 11, 14, 17, 20, 23, 26 and 29 provide a description of the surface of each element of each embodiment Ex1, Ex2, ... Ex 10, respectively. For each lens element and each surface, the following parameters are described: - Surface type (see below). - The lens element number L and the surface number. - The radius of the surface in mm, infinite for flat surfaces. - The thickness between surface i and surface i+1. - The surface refractive index Nd. - The surface Abbe number Vd. - The surface semi-diameter D/2.

Aspherical surface coefficient table:

Tables 3, 6, 9, 12, 15, 18, 21, 24, 27 and 30 provide a further description of the non-spherical surface of each lens element in Examples Ex1, Ex2, ... Ex 10, respectively.

Surface type

a) Q-type 1 surface depression formula:

where {z, r} are the standard cylindrical polar coordinates, c is the paraxial curvature of the surface, k is the cone parameter, rmax is half the clear aperture of the surface, and An is the polynomial coefficient shown in the lens data sheet.

b) Uniform non-spherical surface formula:

The equation for the surface profile for each surface Sk (for k between 1 and 2N) is expressed as:

Wherein "z" is the position of the profile of the surface Sk measured along the optical axis 103 (co-located with the Z axis, where z = 0 corresponds to the intersection of the profile of the surface Sk with the Z axis), "r" is the distance from the optical axis 103 (measured along an axis perpendicular to the optical axis 103), "K" is the cone coefficient, c = 1/R, where R is the radius of curvature, and An (n from 1 to 7) is the coefficient for each surface Sk in Tables 2 and 4. The maximum value of r, "max r", is equal to D/2.

c) plane surface;

d) Termination.

The values provided for these examples are illustrative only, and other values may be used according to other examples.

In the following table, the radius of curvature ("R"), lens element thickness ("T"), and clear aperture are expressed in millimeters.

Row "0" of Tables 1, 3, 5 and 7 describes the parameters associated with the object (not shown in the figure); the object placed 1 km from the system is considered to be at an infinite distance.

The "1" to "8" rows of Tables 1 to 4 describe parameters about surfaces S1 to S8, respectively. The "1" to "10" rows of Tables 5 to 8 describe parameters about surfaces S1 to S10, respectively.

Rows “9”, “10” and “11” of Tables 1 and 3 and rows “11”, “12” and “13” of Tables 5 and 7 respectively describe parameters regarding the surfaces 205a, 205b of the optical element 205 and a surface 202a of the image sensor 202.

In the “i” row of Tables 1, 3 and 5 (i is between 1 and 10 in Tables 1 and 3, and between 1 and 12 in Table 5), the thickness corresponds to the distance between surface Si and surface Si + 1 measured along optical axis 103 (coincident with the Z axis).

In row "11" of Tables 1 and 3 (row "13" of Tables 5 and 7), the thickness is equal to zero because this corresponds to the last surface 202a.

The following list and Table 33 summarize the design features and parameters present in the examples listed above. These features contribute to the goal of achieving a lightweight folding lens with a large lens assembly aperture:

"AA": AA1≡BFL/TTL＞0.35, AA2≡BFL/TTL＞0.4, AA3≡BFL/TTL＞0.5;

"BB": BB1≡CA(S1)/CA(S3)＞1.2, BB2≡CA(S1)/CA(S3)＞1.3, BB3≡CA(S1)/CA(S3)＞1.4;

“CC”: CC1≡T (AS to S3)/TTL＞0.1, CC2≡T (AS to S3)/TTL＞0.135, CC3≡T (AS to S3)/TTL＞0.15;

"DD": at least two gaps meeting DD1≡STD＜0.020, DD2≡STD＜0.015, DD3≡STD＜0.010;

"EE": at least 3 gaps that meet EE1≡STD＜0.035, EE2≡STD＜0.025, EE3≡STD＜0.015;

"FF": at least 4 gaps that meet the requirements of FF1≡STD＜0.050, FF2≡STD＜0.035, FF3≡STD＜0.025;

"GG": GG1 ≡ SDL/CA(S2N) ＞ 1.5, GG2 ≡ SDL/CA(S2N) ＞ 1.55, GG3 ≡ SDL/CA(S2N) ＞ 1.6;

"HH": power symbol sequence;

“II”: At least one gap that meets II1≡STD＜0.01 and OA_Gap / TTL＜1/80, II2≡STD＜0.015 and OA_Gap / TTL＜1/65;

"JJ": JJ1: The Abbe number sequences of lens elements L1, L2 and L3 may be greater than 50, less than 30 and greater than 50 respectively;

JJ2: The Abbe numbers of lens elements L1, L2, and L3 may be greater than 50, less than 30, and less than 30, respectively;

“KK”: KK1≡| f2 / f1 | > 0.4, and the Abbe number sequence of lens elements L1, L2 and L3 may be greater than 50, less than 30 and less than 30, respectively; , KK2≡| f2 / f1 | < 0.5, and the Abbe number sequence of lens elements L1, L2 and L3 may be greater than 50, less than 30 and greater than 50, respectively; and

"LL": LL1 ≡ f1/EFL <0.55, LL2 ≡ f1/EFL <0.45;

“MM”: MM1 ≡ |f2/f1|＜0.9, MM2 ≡ |f2/f1|＜0.5; and

"NN":NN1 ≡ TTL/EFL＜0.99, NN2 ≡ TTL/EFL＜0.97, NN3 ≡ TTL/EFL＜0.95.

"OO": at least two gaps meeting OO1 ≡ STD＞ 0.020, OO2 ≡ STD＞ 0.03, OO3 ≡ STD＞ 0.040;

"PP": at least three gaps that meet PP1≡STD＞ 0.015, PP2≡STD＞ 0.02, PP3≡STD＞ 0.03;

"QQ": at least 4 gaps that meet QQ1≡STD＞ 0.015, QQ2≡STD＞ 0.02, QQ3≡STD＞ 0.03;

“RR”: At least 3 OA_Gaps that meet RR1≡TTL/Min_Gap＞50, RR2≡TTL/Min_Gap＞60, RR3≡TTL/Min_Gap＞100.

Unless otherwise stated, the use of "and/or" in the description between the last two members of a list of options for selection indicates that one selection of one or more of the list options is appropriate and possible.

It should be understood that where a claim or specification refers to "a" or "an" element, such reference should not be interpreted as there being only one of that element.

All patents and patent applications mentioned in the specification are incorporated herein by reference in their entirety, to the same extent as if each individual patent or patent application was specifically and individually designated as incorporated by reference herein. In addition, citation or identification of any reference in this application should not be construed as an admission that the reference is available as prior art for the present disclosure.

without

The following non-limiting examples of the embodiments disclosed herein are described with reference to the figures listed after this paragraph. The figures and descriptions are intended to illustrate and clarify the embodiments disclosed herein and should not be considered to be limiting in any way. The same elements in different figures may be indicated by the same figure labels. The elements in the figures are not necessarily drawn to scale. In the figure: Figure 1A is a generally isometric view of an example of a known folding camera. Figure 1B is a side view of the camera of Figure 1A. Figure 1C is a generally isometric view of an example of a known camera including a folding telephoto sub-camera and a wide-angle sub-camera. Figure 1D is a side view of the camera of Figure 1C. Figure 2A is a schematic diagram of an example of a lens element with light according to some examples of the subject matter disclosed herein. Figure 2B is another schematic diagram of the lens element of Figure 2A. FIG. 3A is a diagrammatic representation of the impact point of an optical line illuminating a convex surface of a lens element, and a diagrammatic representation of the orthogonal projection of the impact point on a plane P, according to some examples of the presently disclosed subject matter. FIG. 3B is a diagrammatic representation of the impact point of an optical line illuminating a concave surface of a lens element, and a diagrammatic representation of the orthogonal projection of the impact point on a plane P, according to some examples of the presently disclosed subject matter. FIG. 4 is a diagrammatic representation of the orthogonal projection of the impact point on a plane P, and a diagrammatic representation of a net height value ("CH"), according to some examples of the presently disclosed subject matter. FIG. 5 is a diagrammatic representation of the orthogonal projection of the impact point on a plane P, and a diagrammatic representation of a clear aperture value ("CA"), according to some examples of the presently disclosed subject matter. FIG. 6 is a diagrammatic representation of another embodiment of a lens element having light, according to some examples of the presently disclosed subject matter. FIG. 7 is also a schematic diagram of another embodiment of a lens element with light according to some examples of the disclosed subject matter. FIG. 8 is a schematic diagram of another embodiment of a lens element with light according to some examples of the disclosed subject matter. FIG. 9 is a schematic diagram of another embodiment of a lens element with light according to some examples of the disclosed subject matter. FIG. 10 is a schematic diagram of another embodiment of a lens element with light according to some examples of the disclosed subject matter. FIG. 11 is a schematic diagram of another embodiment of a lens element with light according to some examples of the disclosed subject matter. FIG. 12 is a schematic diagram of another embodiment of a lens element with light according to some examples of the disclosed subject matter. FIG. 13 is a side view schematic diagram of an optical lens module that maintains the lens element according to some examples of the disclosed subject matter. FIG. 14A is a schematic diagram of another embodiment of a lens element for displaying light according to another example of the disclosed subject matter. FIG. 14B is another schematic diagram of the lens element of FIG. 14A.

Claims (13)

A lens assembly includes: an image sensor; and four or five lens elements, which include, in order from an object side to an image side, a first lens element L1 having positive refractive power and a clear aperture CA (S1), a second lens element L2 having negative refractive power, a third lens element L3 having positive refractive power, and a fourth lens element L4 having negative refractive power, wherein S1 is the first lens element L1 close to the object. a surface on the side of the first lens element L1; wherein all the clear apertures of all other lens elements of the four or five lens elements are no greater than CA(S1); wherein the lens assembly has an effective focal length (EFL) and a total track length (TTL), the total track length being defined as the distance from the surface S1 of the first lens element L1 to the image sensor; wherein TTL/EFL<0.99; wherein the lens assembly is included in a folding camera. A lens assembly as described in claim 1, wherein TTL/EFL<0.97. A lens assembly as described in claim 1, wherein TTL/EFL<0.95. A lens assembly includes: an image sensor; and four or five lens elements, which include, in order from an object side to an image side, a first lens element L1 having positive refractive power and a clear aperture CA (S1), a second lens element L2 having negative refractive power, a third lens element L3 having negative refractive power, and a fourth lens element L4 having positive refractive power, wherein S1 is the first lens element L1 close to the object side. a surface of the first lens element L1; wherein all clear apertures of all other lens elements of the four or five lens elements are no greater than CA(S1); wherein the lens assembly has an effective focal length (EFL) and a total track length (TTL), the total track length being defined as the distance from the surface S1 of the first lens element L1 to the image sensor; wherein TTL/EFL<0.99; wherein the lens assembly is included in a folding camera. A lens assembly includes: an image sensor; and four or five lens elements, which include, in order from an object side to an image side, a first lens element L1 having positive refractive power and a clear aperture CA (S1), a second lens element L2 having negative refractive power, and a fifth lens element L5 having positive refractive power, wherein S1 is a surface of the first lens element L1 close to the object side; All clear apertures of all other lens elements of the four or five lens elements are no greater than CA(S1); wherein the lens assembly has an effective focal length (EFL) and a total track length (TTL), the total track length being defined as the distance from the surface S1 of the first lens element L1 to the image sensor; wherein TTL/EFL<0.99; wherein the lens assembly is included in a folding camera. A lens assembly as described in any one of claims 1 to 3, wherein the four or five lens elements further include a fifth lens element L5 having a negative refractive power. A lens assembly as claimed in any one of claims 1 to 3, wherein an optical window is positioned on a path defining the BFL and the TTL. A lens assembly as described in any one of claims 1 to 3, wherein the first lens element L1 has an f-number f1, wherein f1/EFL<0.55. A lens assembly as described in any one of claims 1 to 3, wherein the first lens element L1 has an f-number f1, wherein f1/EFL<0.45. A lens assembly comprises: an image sensor; and four or five lens elements, which, in order from an object side to an image side, comprise a first lens element L1 having positive refractive power and a clear aperture CA(S1), a second lens element L2 having negative refractive power, a third lens element L3 having positive refractive power, and a fifth lens element L5 having positive refractive power or negative refractive power, wherein the Abbe number of the first lens element L1 is greater than 50, the Abbe number of the second lens element L2 is less than 30, and the Abbe number of the third lens element L5 is less than 50. The Abbe number of the first lens element L3 is greater than 50, wherein S1 is a surface of the first lens element L1 close to the object side; wherein all the clear apertures of all other lens elements of the four or five lens elements are not greater than CA(S1); wherein the lens assembly has an effective focal length (EFL) and a total track length (TTL), the total track length being defined as the distance from the surface S1 of the first lens element L1 to the image sensor; wherein TTL/EFL<0.99; wherein the lens assembly is included in a folding camera. A lens assembly, comprising: an image sensor; and four or five lens elements, in order from an object side to an image side, comprising a first lens element L1 having positive refractive power and a clear aperture CA(S1), a second lens element L2 having negative refractive power, and a third lens element L3 having positive refractive power, wherein S1 is a surface of the first lens element L1 close to the object side; wherein all clear apertures of all other lens elements of the four or five lens elements are not greater than CA(S1); wherein the lens assembly has an effective focal length (EFL) and an Total track length (TTL), the total track length is defined as the distance from the surface S1 of the first lens element L1 to the image sensor; wherein TTL/EFL<0.99; wherein the lens assembly is included in a folding camera, wherein the absolute value of a ratio of the f-number f2 of the second lens element L2 to the f-number f1 of the first lens element L1 |f2/f1| satisfies |f2/f1|>0.4, wherein the Abbe number of the first lens element L1 is greater than 50, the Abbe number of the second lens element L2 is less than 30, and the Abbe number of the third lens element L3 is less than 30. A lens assembly, comprising: an image sensor; and four or five lens elements, including, in order from an object side to an image side, a first lens element L1 having positive refractive power and a clear aperture CA(S1), a second lens element L2 having negative refractive power, and a third lens element L3 having positive refractive power, wherein S1 is a surface of the first lens element L1 close to the object side; wherein all clear apertures of all other lens elements of the four or five lens elements are not greater than CA(S1); wherein the lens assembly has an effective focal length (EFL) and an Total track length (TTL), the total track length is defined as the distance from the surface S1 of the first lens element L1 to the image sensor; wherein TTL/EFL<0.99; wherein the lens assembly is included in a folding camera, wherein the absolute value of a ratio of the f-number f2 of the second lens element L2 to the f-number f1 of the first lens element L1 |f2/f1| satisfies |f2/f1|<0.5, wherein the Abbe number of the first lens element L1 is greater than 50, the Abbe number of the second lens element L2 is less than 30, and the Abbe number of the third lens element L3 is greater than 50. A lens assembly comprises: an image sensor; and four or five lens elements, which, in order from an object side to an image side, comprise a first lens element L1 having positive refractive power and a clear aperture CA(S1), a second lens element L2 having negative refractive power, and a third lens element L3 having positive refractive power, wherein S1 is a surface of the first lens element L1 close to the object side; wherein all clear apertures of all other lens elements of the four or five lens elements are not greater than CA(S1). A(S1); wherein the lens assembly has an effective focal length (EFL) and a total track length (TTL), the total track length being defined as the distance from the surface S1 of the first lens element L1 to the image sensor; wherein TTL/EFL<0.99; wherein the lens assembly is included in a folding camera, wherein the absolute value of a ratio of the f-number f2 of the second lens element L2 to the f-number f1 of the first lens element L1 |f2/f1| satisfies |f2/f1|<0.9.