Folded camera lens design

Abstract

A folding camera having a total track length (TTL), an aperture value less than 1.2, and a large field of view, such as at least 60 degrees. Such a folding camera may include N lens elements, where N≥7, an image sensor, and an optical path folding element for providing a folded optical path between an object and a lens, wherein an aperture stop of the lens is located closer than a distance d to a first surface of the first lens element facing the object, the distance d satisfying d / TTL = 0.2.

Description

[0001] Related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 054,862, filed July 22, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of digital cameras, and more particularly to a folding optical design in such digital cameras.

[0004] definition

[0005] In this application, the following symbols and abbreviations are used for optical and other characteristics mentioned throughout the specification and drawings, all of which are known in the art:

[0006] -Total track length (TTL): The maximum distance between a point on the front surface S1 of a first lens element L1 and an image sensor, measured along a direction parallel to the optical axis of a lens (or lens assembly) when a camera system including a lens is focused to an infinity object distance.

[0007] - Back focal length (BFL): When a camera system including a lens is focused to an infinity object distance, the back focal length (BFL) measured along a direction parallel to the first optical axis at the last lens element L of a lens (or lens assembly). N The rear surface S 2N The minimum distance between a point and an image sensor.

[0008] - Effective focal length (EFL): Lens element L1 to L N The distance between the rear principal point P' and the rear focal point F' of a lens assembly.

[0009] - Aperture value (f-number, f / #): The ratio of EFL to entrance pupil diameter. Background Technology

[0010] Dual-camera or triple-camera (or typically multi-camera) systems are known for use in mobile devices such as smartphones. In a typical triple-camera setup, one camera has an ultra-wide (UV) field of view (FOVUW), another camera has a wide field of view (FOVW) narrower than the UW, and yet another camera has a telephoto field of view (FOVT) narrower than the FOVW. These cameras are also referred to herein as ultra-wide (or UW) cameras, wide (or W) cameras, and telephoto (or T) cameras, respectively. Generally, the wide-angle camera is considered the main camera of a smartphone.

[0011] The aperture value ("f / #") of a camera lens is the ratio of the effective focal length (EFL) to the camera's entrance pupil diameter D: f / # = EFL / D. The entrance pupil is the optical image "seen" through the aperture stop of the lens system's front aperture. The front aperture is the object-side aperture of the lens. Smartphone main cameras require a low f / # because it offers three main advantages: good low-light sensitivity, strong "natural" bokeh, and high image resolution, which will be discussed below:

[0012] 1. Compared to cameras like digital single-lens reflex (DSLR) cameras, low ISO sensitivity is a major performance drawback of today's mobile-compatible cameras. For example, halving the camera's f / # (for the same EFL) increases the aperture area by four times, meaning four times more light enters the camera. This difference is especially significant when capturing low-light scenes.

[0013] 2. Bokeh refers to the blurred aesthetic quality produced by out-of-focus segments in an image, and it is a much-needed feature for today's smartphones. The bokeh effect is inversely proportional to the image's depth of field (DOF), where DOF ~ f / #. A low f / # is beneficial for supporting strong, "natural" bokeh effects. Since the f / # in today's smartphone cameras cannot provide sufficient "natural" bokeh, the need for strong bokeh is met by "artificial" bokeh, that is, artificially applying blur to out-of-focus image segments.

[0014] 3. Image sensors with ever-increasing pixel resolution are entering mobile devices, surpassing 100 megapixels for the first time in 2019. This (along with other factors) is achieved by reducing the size of individual pixels, i.e., increasing the spatial pixel frequency. To translate pixel resolution into image resolution, a camera lens must support the sensor's spatial pixel frequency k.Pixel For a well-designed (diffraction-limited) camera lens, the resolvable spatial frequency k of the lens is... Lens Inversely proportional to f / #: k Lens ~1 / f / #, meaning a lower f / # corresponds to a higher image resolution (assuming an image sensor has a sufficient spatial pixel frequency).

[0015] The latest high-end smartphones feature main wide-angle cameras with f / # of approximately f / 1.9 (Huawei P40 Pro) and f / 1.8 (Apple iPhone 11 Pro Max). A major challenge with low f / # cameras is lens design to correct the strong aberrations introduced by the large front aperture, such as those for chromatic aberration correction. This is typically addressed through a more complex lens design incorporating a large number of lens elements. However, this usually results in a larger total track length (TTL) and a larger camera module height, which is detrimental to achieving the goal of a slim smartphone design.

[0016] Recent developments in telephoto cameras involve using a prism to "fold" the telephoto camera: a reflective or optical path folding element ("OPFE") is added to the optical path to "fold" (tilt) the direction of light propagation from a back surface perpendicular to the host device to a back surface parallel to the host device. Folding cameras allow for large TTLs in a slim camera design.

[0017] To improve the main camera of a smartphone, adopting a low f / # foldable wide-angle camera design would be beneficial. Summary of the Invention

[0018] In various embodiments, a folding camera is provided, comprising: having N lens elements L i A lens, wherein N≥7, the lens having an effective focal length (EFL), each L i Each has its own focal length f i The camera includes a first lens element L1 facing an object; an image sensor; and an optical path folding element (OPFE) for providing a folded optical path to the optical axis of the lens between the object and the lens. The folding camera has a total track length (TTL), wherein an aperture stop of the lens is located closer to a first surface of the first lens element facing the object than a distance d, the distance d satisfying d / TTL = 0.2, and wherein an aperture value (f number, f / #) of the camera is less than 1.2.

[0019] In various embodiments, a folding camera is provided, comprising: a lens having an effective focal length (EFL), and said lens including N lens elements L i Where N≥7, the lens element has a first optical axis, and each lens element has a focal length f. i And includes a respective front surface S 2i-1 and their respective rear surfaces S 2i The lens element surface is marked with S k Where 1≤k≤2N, and the surface S of each lens element k With a clear height value CH(S) k ), where the last surface S 17 Net high value CH(S) 17 ) is greater than or equal to the plurality of surfaces S2 to S 2N-1 Each of the following elements has a height value; an image sensor; and an optical path folding element (OPFE) for providing a folded optical path between an object and the lens element, wherein an aperture value (f number, f / #) of the camera is less than 1.2.

[0020] In some embodiments, f / # < 1.1.

[0021] In some embodiments, f / # ≤ 1.0.

[0022] In some embodiments, 0.8 <f / #≤1.0。

[0023] In some embodiments, one or more of the folding cameras have a field of view (FOV) greater than 60 degrees.

[0024] In some embodiments, |f i |> 4 times EFL, for 1≤i≤3.

[0025] In some embodiments, |f i |> 5 times EFL, for 1≤i≤3.

[0026] In some embodiments, lens element L5 has the strongest optical power, i.e., |f5| < |f i |, for i≠5.

[0027] In some embodiments, f5 <EFL。

[0028] In some embodiments, a lens subsystem including the lens elements L4 and L5 has positive refractive power.

[0029] In some embodiments, the focal length f4 of the lens element L4 and the focal length f5 of the lens element L5 satisfy |f4| < 4 times f5.

[0030] In some embodiments, the focal length f4 of the lens element L4 and the focal length f5 of the lens element L5 satisfy |f4| < 3 times f5.

[0031] In some embodiments, the lens includes at least one air gap between the lens elements, the air gap meeting the condition STD<0.020, where STD is a standardized gap standard deviation.

[0032] In some embodiments, the lens includes at least one air gap between the lens elements, the air gap meeting the condition STD<0.010, where STD is a standardized gap standard deviation.

[0033] In some embodiments, an air gap between lens element L4 and lens element L5 satisfies STD < 0.020, where STD is a standardized gap standard deviation. Attached Figure Description

[0034] The following description, with reference to the accompanying drawings listed after this paragraph, illustrates non-limiting examples of embodiments disclosed herein. The drawings and description are intended to illustrate and explain the embodiments disclosed herein and should not be considered limiting in any way. Identical elements in different drawings may be represented by the same numerals. Elements in the drawings are not necessarily drawn to scale. In the drawings:

[0035] Figure 1A shows a perspective view of a known digital folding camera that can be used as a wide-angle camera operation;

[0036] Figure 1B shows a side view of the camera described in Figure 1A;

[0037] Figure 1C shows a known dual-camera system, which includes a folding camera as shown in Figures 1A and 1B, and a "standing" (non-folding) camera.

[0038] Figure 2A A schematic diagram of a folding optical lens system according to some examples of the subject matter of this disclosure is shown;

[0039] Figure 2B A schematic diagram of another folding optical lens system according to some examples of the subject matter of this disclosure is shown;

[0040] Figure 2CA schematic diagram of yet another folding optical lens system according to some examples of the subject matter of this disclosure is shown;

[0041] Figure 2D A schematic diagram of another folding optical lens system according to some examples of the subject matter of this disclosure is shown;

[0042] Figure 2E Another optical lens system based on some examples of the subject matter of this disclosure is schematically depicted;

[0043] Figure 3A The orthogonal projections IP1 and IP2 of two impact points on a plane P are shown. orth,1 IP orth,2 The plane P and Figures 2A to 2D The optical axes of the lenses in the system are orthogonal.

[0044] Figure 3B The orthogonal projections IP of two impact points IP3 and IP4 on a plane P are shown. orth,3 IP orth,4 The plane P and Figures 2A to 2D The optical axes of the lenses in the system are orthogonal.

[0045] Figure 4 The definition of clear height is provided graphically.

[0046] Figure 5 The definition of clear aperture is provided graphically.

[0047] Figure 6 Provides lens element L i diameter H Li A diagrammatic explanation.

[0048] Figure 7 An exploded view of the lens element is shown, illustrating the width W of the lens element. Li and height H Li . Detailed Implementation

[0049] In the following detailed description, numerous specific details are set forth to provide a thorough understanding. However, those skilled in the art will understand that the subject matter currently disclosed can be practiced without these specific details. In other instances, well-known methods have not been described in detail so as not to obscure the subject matter currently disclosed.

[0050] It should be understood that, for clarity, certain features of the currently disclosed subject matter described in the context of individual embodiments may also be provided in combination in a single embodiment. Conversely, for brevity, various features of the currently disclosed subject matter described in the context of individual embodiments may also be provided individually or in any suitable sub-combination.

[0051] Furthermore, for clarity, the term "substantially" is used here to imply the possibility that the value may vary within an acceptable range. According to one example, the term "substantially" as used herein should be interpreted as implying a possible variation of 10% or less than any specified value. According to another example, the term "substantially" as used herein should be interpreted as implying a possible variation of 5% or less than any specified value. According to a further example, the term "substantially" as used herein should be interpreted as implying a possible variation of up to 2.5% or less than any specified value.

[0052] Figures 1A and 1B illustrate a known digital folding camera 100, which can be used, for example, as a wide-angle camera. The camera 100 includes an optical path folding element (OPFE) 102, such as a prism, and a lens 104 having multiple lens elements (not visible in this illustration, but for example in...). Figures 2A to 2D (as can be seen in the image) and an image sensor 106. In some embodiments (such as...) Figures 2A to 2D The plurality of lens elements are symmetrical about a first optical axis 108. In other embodiments, the plurality of lens elements may not be axially symmetrical. For example, the lens elements may be cut (or diced or sliced) into a non-circular shape, such as... Figure 2B As shown.

[0053] At least some lens elements can be held by a structure referred to as a "lens barrel" 110. The lens barrel can have longitudinal symmetry along the optical axis 108. In Figures 1A to 1C, the cross-section of the lens barrel is circular. However, this is not mandatory, and other shapes can be used, for example, to support cut lens elements.

[0054] The path of a light ray from an object (not shown) to the image sensor 106 defines an optical path (see optical paths 112 and 114, which represent the optical path portions).

[0055] The OPFE folds the optical path from a first optical path 112 to a second optical path 114. The optical path 114 is substantially parallel to the optical axis 108. The optical path is therefore referred to as the "folded optical path" (represented by optical paths 112 and 114) and the camera 100 is referred to as the "folded optical path".

[0056] In particular, in some examples, OPFE 102 is tilted approximately 45° relative to the optical axis 108. In Figure 1A, OPFE 102 is also tilted approximately 45° relative to the optical path 112.

[0057] In some known examples, the image sensor 106 is located in an XY plane substantially perpendicular to the optical axis 108. However, this is not limiting and the image sensor 106 can have different orientations. For example, and as described in WO 2016 / 024192, the image sensor 106 can be in the XZ plane. In this case, an additional OPFE can be used to reflect light toward the image sensor 106.

[0058] Two cameras, such as a wide-angle camera 100 and a standard UW camera 130, can be included in a digital camera 150 (also known as a dual camera). One possible configuration is shown in Figure 1C.

[0059] UW camera 130 may include an aperture 132 (indicating the object side of the camera), an optical lens system 134 (or "wide-angle lens module") having a symmetry (and optical) axis 136 in the Y direction, and a UW image sensor 138. The UW camera includes a UW lens system configured to provide a UW image. As described above, the UW camera has a field of view (FOVUW) greater than the field of view (FOVW) of the wide-angle camera. For example, the FOVUW may be 80 to 130 degrees, while the FOVW may be 60 to 90 degrees. Notably, in other examples, multiple wide-angle cameras and / or multiple telephoto cameras may be incorporated and operated in a single digital camera. The FOVT of a telephoto camera may be, for example, 20 to 50 degrees.

[0060] Now pay attention Figure 2A The diagram schematically depicts an optical lens system disclosed herein and designated 200. Lens system 200 includes an OPFE 202, a lens (or “lens assembly”) 204, an optical element 206, and an image sensor 208. System 200 is shown using ray tracing. Optical element 206 may be, for example, an infrared (IR) filter and / or a glass image sensor dust cover. Light rays (after being reflected by prism 202) pass through lens 204 and form an image on image sensor 208. Figure 2A Three regions are shown, each with three rays: an upper edge ray, a lower edge ray, and a principal ray. Figure 2A In the example, the light rays pass through the optical element 206 before striking the image sensor 208. However, this is not limiting, and in some examples, the optical element 206 is not present; that is, in some lens systems, the optical element is optional.

[0061] Lens 204 includes multiple N lens elements L i 220 (where "i" is an integer between 1 and N). L1 is the lens element closest to the object (prism), L N This is the lens element closest to the image side, i.e., the side where the image sensor is located. This order applies to all lenses and lens elements disclosed herein. Lens element L i These can be used, for example, as lens elements of the aforementioned camera 100. The N lens elements are symmetrical about an optical axis 210. Each lens element L i Including a respective front surface S 2i-1 (Index "2i-1" is the number of the front surface) and a respective rear surface S2i (index "2i" is the number of the rear surface), where "i" is an integer between 1 and N. This numbering convention is used throughout the manual. Alternatively, as done throughout the manual, the lens surface is marked as "S k ", k ranges from 1 to 2N. The front and rear surfaces may be aspherical in some cases. However, this is not limiting."

[0062] As used herein, the term “front surface” for each lens element refers to the surface of the lens element located closer to the camera entrance (camera object side), and the term “rear surface” refers to the surface of the lens element located closer to the image sensor (camera image side).

[0063] In lens system 200, a first horizontal surface of the prism (oriented along the Z direction), denoted as T1, is 10.93 mm. A second horizontal surface of the prism (oriented along the X direction, not shown), denoted as T2, is 12.6 mm. The vertical surface of the prism (along the Y direction), denoted as V, is 8.68 mm. The prism angle is 45 degrees. The relatively large prism size allows a large amount of light to enter the camera, which allows the camera to have a low f / # of 1.0 in this example. In other embodiments, f / # can be from 0.8 to 1.2. The aperture stop of lens 204 is located at a distance d = -0.042 cm from S2, i.e., from the first surface of the first lens element. For the non-zero field shown in lens system 200, approximately 80% of the light reaches image sensor 208.

[0064] As explained below, for each surface S k Define a net height value CH(S) k ), where 1≤k≤2N) and can be for each surface S k Define a light aperture value CA(S) k ), where 1≤k≤2N). CA(S) k ) and CH(S k) defines each surface S of each lens element. k The optical properties. The CH term is a reference. Figure 4 As defined, the CA item is a reference. Figure 5 As defined below.

[0065] In addition, for each lens element L i A height ("H") is defined Li ", for 1≤i≤N). For each lens element L i H Li Lens element L corresponds to the lens element measured along a direction perpendicular to the optical axis of the lens element. i The maximum height. For a given lens element, the height is greater than or equal to the net height CH of the front and rear surfaces of the given lens element and the aperture value CA. Typically, for an axisymmetric lens element, H... Li It is the lens element L i The diameter, such as Figure 6 As shown. Typically, for axisymmetric lens elements, H Li =max{CA(S 2i-1 ),CA(S 2i )}+Dimensions of mechanical parts.

[0066] Generally, in lens design, the dimensions of mechanical parts are defined as having no contribution to the lens's optical characteristics. Therefore, two heights are defined for the lens: an optical height H representing the optically active area (dashed line). opt (Corresponding to the CA value) and a geometric (or mechanical) height H of the lens. L It covers an optically active region and an optically inactive region. The dimensions of the mechanical part are related to H. Li The contribution is typically 200 to 1000 micrometers.

[0067] In lens 204, the last surface S of the last lens element L8. 17 CA 17 The aperture diameter is larger than all other surfaces S of the lens element. i CA, i.e., CA 17 CA i For i < 17. The first surface S of the last lens element L8 16 CA, CA 16 Larger than all previous surfaces S of the lens element i CA, i.e., CA 16 CA i For i < 16.

[0068] In lens system 200, N equals 8. However, this is not limiting and different numbers of lens elements can be used. According to some examples, N is equal to or greater than 7. For example, N can be equal to 7, 8, 9, or 10.

[0069] In lens system 200, some surfaces of the lens element are represented as convex surfaces, while others are represented as concave surfaces. However, Figure 2A The representation is not restrictive and different combinations of convex and / or concave surfaces can be used, depending on various factors such as the application, the required optical power, etc.

[0070] For example, one lens barrel of lens barrel 110 can carry lens 204. In some embodiments, the lens barrel may be circular, such as lens barrel 110. In other embodiments, the lens barrel may not be circular, but may have, for example, a circular shape. Figure 7 The shape of the lens element. (Reference) Figure 7 A non-circular lens barrel may have an X-axis or a Y-axis as its axis of symmetry. A non-circular lens barrel may, for example, be shaped according to the cut lens elements of a lens, such as lens 204'. The height of a lens barrel may be only slightly higher than the lens element with the largest height in the lens. For example, the lens barrel may be 0 to 0.5 mm higher than the tallest lens element. For example, a lens barrel having the same height as the tallest lens element is described in, for example, in the jointly owned international patent application PCT / IB2018 / 050988, the entire contents of which are incorporated herein by reference.

[0071] like Figure 3A , Figure 3B and Figure 4 As shown, passing through surface S k Each light ray (for 1 ≤ k ≤ 2N) strikes a point IP on this surface. The light ray enters the optical lens system 200 from surface S1 and passes through surface S2 to S... 2N Some rays of light can strike any surface. k It is on but cannot / will not reach the image sensor 208. For a given surface S k Only the light rays that can form an image on the image sensor 208 are considered. CH(S) k () is defined as the distance between two closest possible parallel lines, see Figure 4 Lines 400 and 402 are located on a plane P orthogonal to the optical axis of the lens element. Figure 3A and Figure 3B In the representation, plane P is parallel to plane XY and orthogonal to the optical axis 103, such that the orthogonal projections of all impact points IP on plane P are equal to the projections of the impact points IP. orth Located between two parallel lines. This can be applied to each surface S. k(Front and back surfaces, 1≤k≤2N) Define CH(S) k ).

[0072] CH(S k The definition of light rays is independent of the object being imaged, as it refers to any light ray that "can" form an image on the image sensor. Therefore, even if the object being imaged is located against a black background that does not produce light, the definition does not concern this black background, as it refers to any light ray that "can" reach the image sensor to form an image (e.g., light rays emitted by a background that emits light, as opposed to a black background).

[0073] For example, Figure 3A The orthogonal projections IP1 and IP2 of two impact points on a plane P are shown. orth,1 IP orth,2 The plane P is orthogonal to the optical axis 103. For example, in Figure 3A In the representation, surface S k It is a convex surface.

[0074] Figure 3B The orthogonal projections IP of two impact points IP3 and IP4 on a plane P are shown. orth,3 IP orth,4 For example, in Figure 3B In the representation, surface S k It is a convex surface.

[0075] exist Figure 4 In the middle, on plane P, there is a surface S k Orthogonal projection of IP at all impact points orth It lies between parallel lines 400 and 402. Therefore, CH(S) k () is the distance between lines 400 and 402.

[0076] Note Figure 5 Based on the currently published topic, for each given surface S k (For 1≤k≤2N), a light aperture CA(S) k The diameter of a circle is defined as the diameter of a circle that lies in a plane P orthogonal to the optical axis 108 and surrounds all orthogonal projections IP of all impact points on plane P. orth The minimum possible circle. As mentioned above regarding CH(S) k As stated in the text, note that CA(S) k The definition of ) does not depend on the object being imaged.

[0077] like Figure 5 As shown, the circumscribed orthogonal projections of all impact points IP onto plane P are... orth Let be a circle 500. The diameter of circle 500 is defined by CA(S).k ).

[0078] for Figure 2A Examples of lens elements are provided, with detailed optical and surface data given in Tables 1 through 3. The values ​​provided in these examples are purely illustrative, and other values ​​may be used based on other examples.

[0079] Surface types are defined in Table 1, and surface coefficients are defined in Table 2:

[0080] Surface types include:

[0081] a) Plano: a flat surface with no curvature

[0082] b) Formula for surface sag (Q type 1, QT1):

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089]

[0090] Where {z,r} are standard cylindrical polar coordinates, c is the paraxial curvature of the surface, k is the conic parameter, and r norm It is typically half the aperture of the surface, and An is the polynomial coefficient in the lens datasheet. The Z-axis is positive when facing the image.

[0091]

[0092] Table 1

[0093] The value of CA is given as the aperture radius, i.e., CA / 2. The reference wavelength is 555.0 nanometers (nm). Except for the refractive index (“Index”) and Abbe number (Abbe#), the unit is millimeters (mm). Each lens element Li has its own focal length fi, as shown in Table 1.

[0094]

[0095] Table 2

[0096]

[0097] Table 2 (continued)

[0098] exist Figure 2A In the example, the following optical characteristics were achieved: -TTL = 8.34 mm

[0099] -BFL = 1.08 mm

[0100] -EFL = 4.14 mm

[0101] -CA(S 17 CA(S) k ), 1 <k≤2N

[0102] -CA(S 16 CA(S) k ), 1 <k≤2N-1

[0103] -CA(S 15 CA(S) k ), 1 <k<2N-2

[0104] -f / #=1.0

[0105] - The sensor diagonal (SD) is 7 mm, and the sensor width / height aspect ratio is 4:3.

[0106] -Minimum CA / SD ratio: CA(S4) / SD = 0.57

[0107] -Maximum CA / SD ratio: CA(S) 17 ) / SD = 0.94

[0108] - Diagonal field of view (FOV) = 80.44 degrees, horizontal FOV = 68.32 degrees, vertical FOV = 53.48 degrees

[0109] - The distance d from the aperture stop to S2: d = -0.042 mm

[0110] The power (amplitude) of L1, L2, and L3 is relatively low, so |fi| > 5 times EFL for 1 ≤ i ≤ 3

[0111] - L4 and L5 together have positive power; therefore, for a lens subsystem containing L4 and L5, with a thickness of d, as shown in Table 1, its focal length is 1 / (f4+f5)=[1 / f4+1 / f5–d / (f4f5)]>0

[0112] -For L5 production: f5 <EFL

[0113] -L4 and L5 satisfy: |f4 < 3 times f5

[0114] -Minimum gap between L4 and L5: Gap Min =0.04 mm

[0115] - Maximum gap between L4 and L5: Gap Max = 0.0745 mm

[0116] - The average gap between L4 and L5, AVG4: AVG4 = 0.048 mm

[0117] -STD4 of the average gap AVG4(r) between L4 and L5: STD4 = 3.42 x 10 -3 Millimeters.

[0118] The lens 204 can be carried by a lens barrel with a height of, for example, 6.57 mm to 7.2 mm.

[0119] In this specification, "gap" or "air gap" refers to the space between consecutive lens elements. In the case of lens elements 4 and 5, "gap" refers to the air space between the last surface of L4 and the first surface of L5.

[0120] Each gap defines many functions and constants:

[0121] 1. "Gap" i The function (r) (where i is the lens element number and r is the same variable used in Equation 1) is:

[0122] a) For i = 1: Gap1(r) of L2S1 = z(r) + (the distance between the exit surface of the prism and L2S1 along the second optical axis);

[0123] b) For i>1: Gap i (r)=L i+1 S1's z(r)+(L) i S2 and L i+1 S1 (distance along the second optical axis) - L i z(r) of S2;

[0124] c) For r = 0, "OA_Gap" i Defined as Gap i (r = 0);

[0125] 2. "Average Gap Gauge" (AVG) i The constant is given by the following formula:

[0126]

[0127] Where j is a discrete variable from 0 to N, where N is an integer > 10, and r norm It is the surface {L i S2,L i+1 The minimum value of S1} is D / 2.

[0128] 3. Standardized gap standard deviation (STD) i The constant is given by the following formula:

[0129]

[0130] Where r norm It is a curved surface {L i S2,L i+1 The minimum value of S1} is D / 2, N is an integer >10, and AVG i Defined in (Eq.2).

[0131] Now notice Figure 2B This schematically depicts another optical lens system disclosed herein and designated 200'. Lens system 200' includes an OPFE 202, a lens 204' having multiple lens elements, an optical element 206, and an image sensor 208. (As...) Figure 2A Ray tracing is provided. Detailed optical and surface data are given in Tables 1 and 2. However, all surfaces of L6 and L8, as well as the S-ray tracing of L7, are not shown. 15 The surface aperture radius data will be replaced with 2.5 mm in the y direction (no change in the x direction).

[0132] To achieve a folding lens system with both a low f / # and a low lens height, the lens element is cut into a non-circular shape (commonly referred to as a "cut lens" or "D-cut lens"). The lens element is obtained by cutting the large lens element of lens 204' to a height of 5 mm (in the Y direction). That is, the height H of lens 204' is... Li >5mm lens element L i (i.e., L6, L7, and L8) are cut to 5 mm. Unlike lens element 204, the cut lens elements do not have circular symmetry, but their width is greater than their height, i.e., W. Li >H Li (see Figure 7 (Example in the text). The height H of lens 204 Li For lens elements ≤5mm, Li remains unchanged. During the cutting process, the CA of lens elements L6, L7, and L8 is large, but CH remains low. This is beneficial because in folding lens designs, the lens height H... LThe camera height can be determined, as it is typically limited by the height of the host device. Lenses with a large CA and low CH are advantageous for compatibility with low f / # folding lenses, such as those used in smartphones, which have height limitations. The lens element of lens 204' is cut along the Y direction, meaning that the lens element H... Li The height is less than its width W Li The CA of lens elements L1 to L5 can be oriented in any direction, such as the Y direction. In the cutting design, the CA of lens elements L6, L7, and L8 are oriented in the X direction (not shown here). In other embodiments, only one or only two lens elements L can be cut. i That is, it can have W Li >H Li In some other embodiments, more than three lens elements L can be cut. i That is, it can have W Li >H Li In yet another embodiment, all lens elements L i All can be cut, that is, they can have W. Li >H Li In other embodiments, lens 204' can be implemented by cutting the large lens element of lens 204 to a height of, for example, 4.5 mm or 4 mm (in the Y direction), i.e., height H. Li Lens elements >4.5 mm (i.e., L4, L5, L6, L7, and L8) or 4 mm (i.e., L1 to L8) i It can be cut to 4.5 mm or 4 mm respectively. In some other embodiments, the lens 204' can be formed by cutting the large lens element of the lens 204 to a height of, for example, 3.5 mm or 3 mm (in the Y direction).

[0133] In lens system 200', the prism dimensions are the same as in lens system 200: T1 = 10.93 mm, T2 = 12.6 mm, V = 8.68 mm.

[0134] Apart from Figure 2A In addition to the features described in the text, Figure 2B In the example, the following optical properties were also implemented:

[0135] -CA(S 12 )=1.03x CH(S 12 = 2.58 mm

[0136] -CA(S 13 )=1.03x CH(S 13 = 2.58 mm

[0137] -CA(S 15 )=1.14x CH(S 15= 2.85 mm

[0138] -CA(S 16 )=1.19x CH(S 16 = 2.97 mm

[0139] -CA(S 17 )=1.32x CH(S 12 = 3.29 mm

[0140] -CA(S 17 CA(S) k ), 1 <k≤2N

[0141] -CA(S 16 CA(S) k ), 1 <k≤2N-1

[0142] -CA(S 15 CA(S) k )<,1 <k<2N-2

[0143] -For all lens surfaces CH(S) k ≤ mm

[0144] -f / #=1.0

[0145] -Minimum CA / SD ratio: CA(S4) / SD = 0.57

[0146] -Maximum CA / SD ratio: CA(S) 17 ) / SD = 0.71

[0147] Lens 204' can be carried by a lens barrel with a height of, for example, 5.0 mm to 5.5 mm.

[0148] Figure 2C Another optical lens system disclosed herein, designated 200", is schematically depicted. Lens system 200" includes an OPFE 202', a lens 204, an optical element 206, and an image sensor 208. (As follows...) Figure 2A Ray tracing is shown. Detailed optical and surface data are given in Tables 1 and 2. Figure 2A and Figure 2B Compared to the OPFE shown, the OPFE 202' has a smaller prism height (“V”) of 7.82 mm. The smaller prism height may be advantageous for achieving a slim folding camera.

[0149] Here, T1 = 9.815 mm, T2 = 12.6 mm, and V = 7.82 mm. For the non-zero field of lens system 200", the light reduction is 8% or less compared to optical lens systems 200 and 200'. For zero field, the amount of light entering the camera remains unchanged. The large amount of light entering the camera allows the camera's f / # to be as low as 1.0. In other embodiments, f / # can be from 0.8 to 1.2.

[0150] Figure 2D Another optical lens system disclosed herein, designated 200", is schematically depicted. Lens system 200" includes an OPFE 202", a lens 204, an optical element 206, and an image sensor 208. (As follows) Figure 2A Ray tracing is shown. Detailed optical and surface data are given in Tables 1 and 2. Figure 2C Compared to the OPFE 202' shown, the OPFE 202” has a smaller prism height (“V”) of 7.02 mm.

[0151] Here, T1 = 8.75 mm, T2 = 12.6 mm, and V = 7.02 mm. For a non-zero field of view of lens system 200”', the light reduction is 19% or less compared to lens systems 200 and 200'. For zero field, the amount of light entering the camera remains unchanged. The large amount of light entering the camera allows the camera's f / # to be as low as 1.0. In other embodiments, f / # can be from 0.8 to 1.2.

[0152] Figure 2E Another optical lens system disclosed herein is schematically depicted and designated 20.0”". Lens system 200”” includes an OPFE 202”, a lens 204”, an optical element 206, and an image sensor 208. As... Figure 2A Ray tracing is provided. Detailed optical and surface data are given in Tables 1 and 2. However, the aperture radius data for all surfaces of L6 and L8, and surfaces S11 of L5 and S15 of L7, will be replaced with 2.45 mm in the y-direction (no change in the x-direction). The prism height (measured along the Y-axis) is greater than the lens height of 204”. The height of the entire lens system 200”” (measured along the Y-axis) is determined solely by the prism height; that is, the lens 204” does not introduce any additional “height loss”.

[0153] and Figure 2D Compared to the OPFE 202” shown, the OPFE 202” prism has a smaller height of 6.00 mm.

[0154] The 204” lens element is obtained by cutting a large 204” lens element to a height of 4.9 mm (in the Y direction). That is, the height H of the 204” lens is...Li >4.9mm lens element L i (L6, L7, and L8) are cut to 4.9 mm. Unlike lens element 204, the cut lens elements do not have circular symmetry, but their width is greater than their height, i.e., W. Li >H Li (see Figure 7 (Example in the text). In other embodiments, lens 204” can be implemented by cutting the large lens element of lens 204 to a height of, for example, 4.5 mm or 4 mm (in the Y direction), i.e., height H. Li Lens elements >4.5 mm (i.e., L4, L5, L6, L7, and L8) or 4 mm (i.e., L1 to L8) i It can be cut into 4.5 mm or 4 mm pieces respectively.

[0155] exist Figure 2B Further explanation regarding the cut lens is provided in the description. Here, T1 = 6.95 mm, T2 = 12.6 mm, and V = 6.00 mm. For the non-zero field shown in lens system 200””, approximately 55% to 60% of the light reaches image sensor 208. For the non-zero field of lens system 200””, the light reduction is approximately 30% compared to the respective non-zero fields of lens systems 200 and 200'. The light reduction is primarily caused by the smaller prism size. The upper and lower edge rays undergo symmetrical light reduction. For the D-type cut lens and the non-D-type cut lens in lens system 200””, the difference in the amount of light reaching image sensor 208 is less than 5%. For zero field, the amount of light entering the camera does not change. The large amount of light entering the camera allows the camera's f / # to be as low as 1.0. In other embodiments, f / # can be from 0.8 to 1.2. Lens 204” can be carried by a lens barrel with a barrel height of, for example, 4.9 mm to 5.5 mm.

[0156] According to some examples, at least a portion of the lens element can have a non-circular shape (profile) in cross-section (in a plane XY, which is orthogonal to the optical lens system and typically coincides with the optical axis). In particular, as shown in the figure, for example in... Figure 7 In the middle, the width W of at least some lens elements integrated in the lens barrel 710 Li (Measured along the X-axis) greater than their height H Li (Measured along the Y-axis). Height H Li The total height of the lens elements (including mechanical parts) can correspond to this. In some embodiments, the lens elements in the lens system 700 may have symmetry about the Y-axis and / or about the X-axis.

[0157] Based on some examples, W Li Significantly greater than H Li(For example, at least 20% higher or greater; these values ​​are not limiting). In some examples, W Li It can be compared to H Li A percentage greater than 20% to 70%. Taking the L8 lens element of the 204' folding lens as an example: W L8 H L8 32% larger. Another example is the folding lens element L8:W 204”. L8 H L8 Larger by 44%.

[0158] Unless otherwise stated, the use of "and / or" between the last two members of the list of options indicates that it is appropriate and permissible to select one or more of the listed options.

[0159] It should be understood that when the claim or specification refers to the element “a” or “an”, such reference should not be interpreted as the existence of only one of that element.

[0160] All patents and patent applications mentioned in this specification are incorporated herein by reference in their entirety to the same extent that each individual patent or patent application is specifically and individually incorporated herein by reference. Furthermore, any reference or designation of any reference in this application should not be construed as an admission that such reference is used as prior art in this disclosure.

Claims

1. A folding camera, comprising: a) A lens having an effective focal length (EFL) and comprising N lens elements L along a lens optical axis. i Where N≥7, and a first lens element L faces an object side, each lens element L i Including a respective front surface S 2i-1 and their respective rear surfaces S 2i The lens element surface is marked with S k Where 1≤k≤2N, and the surface S of each lens element k It has a net high value CH(S) k ) and a light aperture value CA(S) k ); b) A lens barrel that carries the lens; c) An image sensor; as well as d) An optical path folding element (OPFE) for folding a first optical path into a second optical path, wherein the first optical path is parallel to a plane containing the image sensor, and the second optical path is perpendicular to the first optical path and parallel to the lens optical axis; The folding camera has a total track length (TTL), wherein an aperture stop of the lens is located closer to a first surface of the first lens element facing the object than a distance d, the distance d satisfying d / TTL = 0.2, and wherein the camera has an aperture value (f number, f / #) < 1.2, and wherein the last lens element L N The aperture value CA (S) of the last surface 2N () greater than the surface area S of the lens element k The light aperture value CA (S) k ), where 1≤k≤2N-1.

2. The folding camera as described in claim 1, characterized in that: The aperture value is <1.

1.

3. The folding camera as described in claim 1, characterized in that: The aperture value is ≤1.

0.

4. The folding camera of claim 1 further includes an optical element, wherein the optical element is located between the lens and the image sensor.

5. The folding camera as described in claim 1, characterized in that: The camera has a field of view (FOV) of more than 60 degrees.

6. The folding camera as described in claim 1, characterized in that: At least some of the lens elements are of a width W Li Greater than a height H Li Cutting lens elements, wherein the height H Li It is measured along a direction parallel to the first optical path, and wherein W is... Li It is measured along a direction perpendicular to both the first and second optical paths.

7. The folding camera as described in claim 1, characterized in that: At least some of the lens elements have a width W Li and a height H Li It satisfies the width W Li / height H Li >1.

1.

8. The folding camera as described in claim 1, characterized in that: At least some of the lens elements have a width W Li and a height H Li It satisfies the width W Li / height H Li >1.

2.

9. The folding camera as described in claim 1, characterized in that: The lens barrel has a lens barrel height of ≤5.5 mm.

10. The folding camera as described in claim 1, characterized in that: The image sensor has a sensor diagonal SD, which is >6 mm.

11. The folding camera as described in claim 1, characterized in that: The optical path folding element has a height H O The lens has a height H L And wherein the height H O The height H L The height H O and the height H L It was measured along a direction parallel to the first optical path.

12. The folding camera as described in claim 1, characterized in that: The height H of the optical path folding element O >One lens barrel height H LB The optical path folding element is of height H. O and the height H of the lens barrel LB It was measured along a direction parallel to the first optical path.

13. The folding camera as described in claim 1, characterized in that: The camera has a height H formed by the optical path folding element. O Determine a height H C And wherein the height H O and the height H C It was measured along a direction parallel to the first optical path.

14. The folding camera as described in claim 1, characterized in that: |f i |> 5 times the effective focal length (5xEFL), for 1≤i≤3.

15. The folding camera as described in claim 1, characterized in that: The lens element L5 has the strongest optical power of all lenses, |f5|<|fi|, for i≠5.

16. The folding camera as described in claim 1, characterized in that: f5 < the effective focal length (EFL).

17. The folding camera as described in claim 1, characterized in that: A lens subsystem including the lens elements L4 and L5 has positive refractive power.

18. The folding camera as described in claim 1, characterized in that: The focal length f4 of the lens element L4 and the focal length f5 of the lens element L5 satisfy |focal length f4| < 4 times the focal length f5 (4xf5).

19. The folding camera as described in claim 1, characterized in that: The focal length f4 of the lens element L4 and the focal length f5 of the lens element L5 satisfy |focal length f4| < 3 times the focal length f5 (3xf5).

20. The folding camera as described in claim 1, characterized in that: The lens includes at least one air gap between the lens elements, the air gap meeting the condition STD<0.020, where STD is a standardized gap standard deviation.

21. The folding camera as described in claim 1, characterized in that: An air gap between lens element L4 and lens element L5 satisfies STD < 0.020, where STD is a standardized gap standard deviation.

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