Patent Description:
Dual-aperture zoom cameras (also referred to as dual-cameras), in which one camera (also referred to as "sub-camera") has a Wide FOV ("Wide sub-camera") and the other has a narrow FOV ("Tele sub-camera"), are known.

International patent publication <CIT>, discloses a "folded camera module" (also referred to simply as "folded camera") that reduces the height of a compact camera. In the folded camera, an optical path folding element (referred to hereinafter as "OPFE") e.g. a prism or a mirror (otherwise referred to herein collectively as "reflecting element") is added in order to tilt the light propagation direction from perpendicular to the smart-phone back surface to parallel to the smart-phone back surface. If the folded camera is part of a dual-aperture camera, this provides a folded optical path through one lens assembly (e.g. a Tele lens). Such a camera is referred to herein as "folded-lens dual-aperture camera". In general, the folded camera may be included in a multi-aperture camera, for example together with two "non-folded" (upright) camera modules in a triple-aperture camera.

A small height of a folded camera is important to allow a host device (e.g. a smartphone, tablets, laptops or smart TV) that includes it to be as thin as possible. The height of the camera is often limited by the industrial design. In contrast, increasing the optical aperture of the lens results in an increase in the amount of light arriving at the sensor and improves the optical properties of the camera.

Therefore, there is a need for, and it would be advantageous to have a folded camera in which the height of the lens optical aperture is maximal for a given camera height and/or for a lens module height.

In some exemplary embodiments, the optical lens module includes a cavity that holds the plurality of lens elements, wherein a height of cavity, measured along an axis orthogonal to the first optical axis, is variable along the first optical axis.

In some exemplary embodiments, the cavity comprises a first portion in which the first lens element L<NUM> is located and a second portion at which at least one of the other lens elements is located, and wherein the height of the first portion of the cavity is greater than the height of the second portion of the cavity.

In some exemplary embodiments, the optical lens module further comprises a lens barrel (or simply "barrel") with a cavity in which at least some of lens elements L<NUM> to LN are held and wherein lens element L<NUM> is located outside of the barrel.

According to another aspect of the presently disclosed subject matter, a camera described above is a Tele sub-camera configured to provide a Tele image and is included together with a Wide sub-camera configured to provide a Wide image in a dual-camera.

According to another aspect of the presently disclosed subject matter, there is provided a digital camera comprising N lens elements having a symmetry along a first optical axis, wherein N is equal to or greater than <NUM>, an image sensor, a reflecting element operative to provide a folded optical path between an object and the image sensor, and a barrel with a cavity in which the plurality of lens elements are held, wherein a height of cavity, measured along an axis orthogonal to the first optical axis, is variable along the first optical axis, wherein the cavity comprises a first portion in which the first lens element L<NUM> is located and a second portion at which at least one of the other lens elements is located, and wherein the height of the first portion of the cavity H<NUM> is greater than the height of the second portion of the cavity H<NUM>, so that H<NUM> > <NUM> × H<NUM>.

According to another aspect of the presently disclosed subject matter, there is provided a digital camera comprising N lens elements L<NUM> to LN having axial symmetry along a first optical axis, wherein N is equal to or greater than <NUM>, an image sensor, a reflecting element operative to provide a folded optical path between an object and the image sensor, and a barrel with a cavity in which at least some of the lens elements L<NUM> to LN are held, and wherein the lens element L<NUM> is located outside of barrel.

In an exemplary embodiment, LN is located outside the barrel.

According to some aspects of the presently disclosed subject matter, there is provided an optical lens module comprising a barrel having a cavity surrounded by walls and N lens elements L<NUM> to LN, wherein N is equal to or greater than <NUM>, wherein L<NUM> has a portion which is not completely surrounded by the cavity and wherein walls of the cavity are aligning a center of lens element L<NUM> with the first optical axis.

In an exemplary embodiment, LN has a portion which is not completely surrounded by the cavity and wherein walls of the cavity are aligning a center of lens element LN with the first optical axis.

In an exemplary embodiment, at least one of an extremity of the walls and an extremity of lens element L<NUM> is shaped so that the extremity of the walls acts a stop for at least a portion of lens element L<NUM>, thereby substantially aligning a center of lens element L<NUM> with the first optical axis.

In an exemplary embodiment, a first portion of lens element L<NUM> is located in the cavity between the extremity of the walls and a second portion of lens element L<NUM> is located outside the barrel and wherein a thickness of the second portion of lens element L<NUM> along the first optical axis is greater than a thickness of the first portion of lens element L<NUM> along the first optical axis.

In an exemplary embodiment, a cross-section of the extremity of the walls has a stepped shape.

In an exemplary embodiment, a cross-section of the extremity of lens element L<NUM> has a stepped shape.

In an exemplary embodiment, a cross-section of the extremity of the walls has a sloping shape.

In an exemplary embodiment, the extremity of the walls comprises a chamfer.

In an exemplary embodiment, the lens module further comprises a cover for protecting the lens, the cover covering lens element L<NUM>.

In an exemplary embodiment, the cover has an extreme point beyond lens element L<NUM>.

In an exemplary embodiment, the cover blocks light from entering a mechanical part of lens element L<NUM>.

According to some aspects of the presently disclosed subject matter, there is provided an optical lens module comprising a plurality N ≥ <NUM> of lens elements Li wherein <NUM> ≤ i ≤ N, each lens element comprising a respective front surface S2i-<NUM> and a respective rear surface S2i, the lens element surfaces marked Sk where <NUM>≤ k ≤ 2N, wherein each lens element surface has a clear aperture value CA(Sk), wherein CA(S<NUM>) is substantially equal to CA(S2N) and wherein CA(S<NUM>) is greater CA(Sk) for <NUM> ≤ k ≤ 2N-<NUM>.

According to some aspects of the presently disclosed subject matter, there is provided an optical lens module comprising a plurality N ≥ <NUM> of lens elements Li wherein <NUM> ≤ i ≤ N, each lens element comprising a respective front surface S<NUM>-<NUM> and a respective rear surface S2i, the lens element surfaces marked Sk where <NUM>≤ k ≤ 2N, wherein each lens element surface has a clear aperture value CA(Sk) and wherein CA(S<NUM>) is greater CA(Sk) for <NUM> ≤ k ≤ 2N.

According to some aspects of the presently disclosed subject matter, there is provided a digital camera comprising an image sensor, a reflecting element operative to provide a folded optical path between an object and the image sensor, and an optical lens module as described above.

According to another aspect of the presently disclosed subject matter, there is provided an optical lens module comprising a barrel having a barrel height H and N lens elements L<NUM> to LN, wherein N is equal to or greater than <NUM> and wherein a height HL1 of lens element L<NUM> satisfies or fulfills HL1 ≥ H. In an exemplary embodiment, HLN ≥ H. In an exemplary embodiment, HLN=HL1.

According to another aspect of the presently disclosed subject matter, there is provided an optical lens module comprising N lens elements L<NUM> to LN, wherein N ≥ <NUM>, wherein each lens element Li has a height HLi for <NUM>≤ i ≤ N and wherein HL1 ≥ HLN > HL2.

In an exemplary embodiment, HL1 > HLi for <NUM>≤ i ≤ N-<NUM>.

According to another aspect of the presently disclosed subject matter, there is provided a method for assembling an optical lens module, comprising: inserting a first lens element L<NUM> of N lens elements into a barrel from an object side of the barrel, fixedly attaching lens element L<NUM> to the barrel, inserting other lens elements L<NUM> to LN and spacers R<NUM> to RN that separate respective lens elements from an image side of the barrel in an insertion order R<NUM>, L<NUM>. RN-<NUM>, LN, and fixedly attaching lens element LN to the lens module.

According to another aspect of the presently disclosed subject matter, there is provided a mobile electronic device comprising an internal digital camera integrated inside a housing of the mobile electronic device, wherein the digital camera is in accordance with any one of the aspects mentioned above, or comprises any of the optical lens module described above.

According to another aspect of the presently disclosed subject matter there is provided a multiple-aperture camera comprising at least one Wide sub-camera and at least one Tele sub-camera, which is in accordance with any one of the aspects mentioned above, or comprises any of the optical lens module described above.

According to another aspect of the presently disclosed subject matter, the reflecting element is a rotating reflecting element capable of being rotated around one or two axes in order to move the position of a field of view (FOV) of the digital camera and capture a plurality of adjacent non-overlapping or partially overlapping images at a plurality of respective positions, and the digital camera is configured to generate from the plurality of images a composite image having an overall image FOV greater than an FOV of the digital camera.

In some exemplary embodiment, the digital camera according to the above aspect further comprises an actuator configured to apply rotational movement around one or two axes to the rotating reflecting element, the actuator operatively connected to a controller configured to control the actuator to cause the camera to scan an area corresponding to a requested zoom factor, the area being greater than the FOV of the digital camera, and to capture the plurality of images where each image is captured at a different position in the scanned area.

In an exemplary embodiment, the size of the composite image is generated by the stitching of <NUM> Tele images.

In an exemplary embodiment, a combined size of the plurality of image is greater than the size of the composite image.

Non-limiting examples of embodiments disclosed herein are described below with reference to figures attached hereto that are listed following this paragraph. The drawings and descriptions are meant to illuminate and clarify embodiments disclosed herein, and should not be considered limiting in any way. Like elements in different drawings may be indicated by like numerals. Elements in the drawings are not necessarily drawn to scale. In the drawings:.

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding. However, it will be understood by those skilled in the art that the presently disclosed subject matter may be practiced without these specific details. In other instances, well-known methods have not been described in detail so as not to obscure the presently disclosed subject matter.

It is appreciated that certain features of the presently disclosed subject matter, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the presently disclosed subject matter, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The term "processing unit" as disclosed herein should be broadly construed to include any kind of electronic device with data processing circuitry, which includes for example a computer processing device operatively connected to a computer memory (e.g. digital signal processor (DSP), a microcontroller, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), etc.) capable of executing various data processing operations.

Furthermore, for the sake of clarity the term "substantially" is used herein to imply the possibility of variations in values within an acceptable range. According to one example, the term "substantially" used herein should be interpreted to imply possible variation of up to <NUM>% over or under any specified value. According to another example, the term "substantially" used herein should be interpreted to imply possible variation of up to <NUM>% over or under any specified value. According to a further example, the term "substantially" used herein should be interpreted to imply possible variation of up to <NUM>% over or under any specified value.

<FIG> illustrate a known digital folded camera <NUM>, which may operate for example as a Tele camera. Digital camera <NUM> comprises a first reflecting element (e.g. mirror or prism, and also referred to sometimes as "optical path folding element" (OPFE)) <NUM>, a plurality of lens elements (not visible in this representation, but visible e.g. in <FIG> and <FIG>) and an image sensor <NUM>. The lens elements (and also barrel, the optical lens module) may have axial symmetric along a first optical axis <NUM>. At least some of the lens elements can be held by a structure called a "barrel" <NUM>. An optical lens module comprises the lens elements and the barrel. The barrel can have a longitudinal symmetry along optical axis <NUM>. In <FIG>, the cross-section of this barrel is circular. This is however not mandatory and other shapes can be used.

The path of the optical rays from an object (not shown) to image sensor <NUM> defines an optical path (see optical paths <NUM> and <NUM>, which represent portions of the optical path).

OPFE <NUM> may be a prism or a mirror. As shown in <FIG>, OPFE <NUM> can be a mirror inclined with respect to optical axis <NUM>. In other cases (not shown, see for example PCT/IB2017/<NUM>), OPFE <NUM> can be a prism with a back surface inclined with respect to optical axis <NUM>. OPFE folds the optical path from a first optical path <NUM> to a second optical path <NUM>. Optical path <NUM> is substantially parallel to the optical axis <NUM>. The optical path is thus referred to as "folded optical path" (indicated by optical paths <NUM> and <NUM>) and camera <NUM> is referred to as "folded camera". The lens module comprises the plurality of lens elements.

In particular, in some examples, OPFE <NUM> can be inclined at substantially <NUM><NUM> with respect to optical axis <NUM>. In <FIG>, OPFE <NUM> is also inclined at substantially <NUM><NUM> with respect to optical path <NUM>.

In some known examples, image sensor <NUM> lies in a X-Y plane substantially perpendicular to optical axis <NUM>. This is however not limiting and the image sensor <NUM> can have a different orientation. For example, and as described in <CIT>, image sensor <NUM> can be in the XZ plane. In this case, an additional OPFE can be used to reflect the optical rays towards image sensor <NUM>.

According to some examples, image sensor <NUM> has a rectangular shape. According to some examples, image sensor <NUM> has a circular shape. These examples are however not limiting.

In various examples camera <NUM> may be mounted on a substrate <NUM>, e.g. a printed circuit board (PCB), as known in the art.

Two sub-cameras, for example a regular Wide sub-camera <NUM> and a Tele sub-camera <NUM> may be included in a digital camera <NUM> (also referred to as dual-camera or dual-aperture camera). A possible configuration is described with reference to <FIG>. In this example, Tele sub-camera <NUM> is according to the camera described with reference to <FIG>. The components of Tele sub-camera <NUM> thus have the same reference numbers as in <FIG>, and are not described again.

Wide camera <NUM> can include an aperture <NUM> (indicating object side of the camera) and an optical lens module <NUM> (or "Wide lens module" in short) with a symmetry (and optical) axis <NUM> in the Y direction, as well as a Wide image sensor <NUM>. The Wide sub-camera comprises a Wide lens module configured to provide a Wide image, wherein the Wide sub-camera has a Wide field of view (FOVW) and the Tele sub-camera has a Tele field of view (FOVT) narrower than FOVw. Notably, in other examples a plurality of Wide sub-cameras and/or a plurality of Tele sub-cameras can be incorporated and operative in a single digital camera.

According to one example, the Wide image sensor <NUM> lies in the X-Z plane, while image sensor <NUM> (which is in this example is a Tele image sensor) lies in a X-Y plane substantially perpendicular to optical axis <NUM>.

In the examples of <FIG>, camera <NUM> can further include (or be otherwise operatively connected to) a processing unit comprising one or more suitably configured processors (not shown) for performing various processing operations, for example processing the Tele image and the Wide image into a fused output image.

The processing unit may include hardware (HW) and software (SW) specifically dedicated for operating with the digital camera. Alternatively, a processor of an electronic device (e.g. its native CPU) in which the camera is installed can be adapted for executing various processing operations related to the digital camera (including, but not limited to, processing the Tele image and the Wide image into an output image).

Attention is now drawn to <FIG> and <FIG>, which show schematic view of a lens module <NUM> having lens elements shown with optical rays according to some examples of the presently disclosed subject matter. Lens module <NUM> is shown without a lens barrel. <FIG> shows optical ray tracing of lens module <NUM> while <FIG> shows only the lens elements for more clarity. In addition, both figures show an image sensor <NUM> and an optical element <NUM>.

Lens module <NUM> includes a plurality of N lens elements Li (wherein "i" is an integer between <NUM> and N). L<NUM> is the lens element closest to the object side and LN is the lens element closest to the image side, i.e. the side where the image sensor is located. This order holds for all lenses and lens elements disclosed herein. Lens elements Li can be used e.g. as lens elements of camera <NUM> represented in <FIG> or as lens elements of the Tele sub-camera <NUM> of <FIG>. As shown, the N lens elements are axial symmetric along optical axis <NUM>.

In the examples of <FIG> and <FIG>, N is equal to four. This is however not limiting and a different number of lens elements can be used. According to some examples, N is equal to or greater than <NUM>. For example, N can be equal to <NUM>, <NUM>, <NUM>, <NUM> or <NUM>.

In the examples of <FIG> and <FIG>, some of the surfaces of the lens elements are represented as convex, and some are represented as concave. The representation of <FIG> and <FIG> is however not limiting and a different combination of convex and/or concave surfaces can be used, depending on various factors such as the application, the desired optical power, etc..

Optical rays (after their reflection by a reflecting element, such as OPFE <NUM>) pass through lens elements Li and form an image on an image sensor <NUM>. In the examples of <FIG> and <FIG>, the optical rays pass through an optical element <NUM> (which comprises a front surface 205a and a rear surface 205b, and can be e.g. a cut-off filter) before impinging on image sensor <NUM>. This is however not limiting, and in some examples, optical element <NUM> is not present. Optical element <NUM> may be for example infra-red (IR) filter, and\or a glass image sensor dust cover.

Each lens element Li comprises a respective front surface S2i-<NUM> (the index "2i-<NUM>" being the number of the front surface) and a respective rear surface S2i (the index "2i" being the number of the rear surface), where "i" is an integer between <NUM> and N. This numbering convention is used throughout the description. Alternatively, as done throughout this description, lens surfaces are marked as "Sk", with k running from <NUM> to 2N. The front surface and the rear surface can be in some cases aspherical. This is however not limiting.

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

As explained below, a clear height value CH(Sk) can be defined for each surface Sk for <NUM> ≤ k ≤ 2N), and a clear aperture value CA(Sk) can be defined for each surface Sk for <NUM> ≤ k ≤ 2N). CA(Sk) and CH(Sk) define optical properties of each surface Sk of each lens element.

In addition, and as shown e.g. in <FIG>, a height ("HLi", for <NUM> ≤ i ≤ N) is defined for each lens element Li. HLi corresponds, for each lens element Li, to the maximal height of lens element Li measured along an axis perpendicular to the optical axis of the lens elements (in the example in <FIG>, HLi is measured along optical path <NUM> which is perpendicular to optical axis <NUM>). For a given lens element, the height is greater than, or equal to the clear height value CH and the clear aperture value CA of the front and rear surfaces of this given lens element. Typically, for an axial symmetric lens element, HLi is the diameter of lens element Li as seen in <FIG>. Typically, for an axial symmetric lens element, HLi = max{CA(S2i-<NUM>), CA(S2i)} + mechanical part size. The mechanical part and its properties are defined below (<FIG> and <FIG>). The mechanical part size contribution to HLi is typically <NUM>-<NUM>.

In addition, as also shown in <FIG>, a height H is defined for the lens barrel. For any axis A which is perpendicular to the optical axis of a lens module, a diameter DA is defined as the maximal distance measured along axis A of the lens module. H is defined as the minimum of all DAs for all possible axes A. In the example in <FIG>, H corresponds to the maximal height of the barrel measured along an axis perpendicular to the optical axis <NUM> of the lens module and parallel to optical path <NUM>.

In addition, as also shown in <FIG>, a height He is defined for the cavity of a lens barrel. He corresponds to the height of the cavity barrel measured along an axis perpendicular to the optical axis of the lens module (in the example in <FIG>, He is measured along optical path <NUM> which is perpendicular to optical axis <NUM>). In some examples, where the cavity barrel is axial- symmetric, He is the internal diameter of the cavity barrel.

According to some examples of the presently disclosed subject matter, the closest lens element to the object side (L<NUM>) has a height which is greater than the height of each of the other lens elements. A non-limiting example is shown in <FIG>, where HL1 is greater than HL2, HL3 and HL4.

According to some examples of the presently disclosed subject matter, the closest lens element to the object side (L<NUM>) and the closest lens element to the image sensor (LN) have a height which is substantially equal and is greater than the height of each of the other lens elements. A non-limiting example is shown in <FIG>, where HL1 equal to HL5 and are greater than HL2, HL3 and HL4.

As shown in <FIG> and <FIG>, each optical ray that passes through a surface Sk (for <NUM> ≤ k ≤ 2N) impinges this surface on an impact point IP. Optical rays enter lens module <NUM> from surface S<NUM>, and pass through surfaces S<NUM> to S2N consecutively. Some optical rays can impinge on any surface Sk but cannot /will not reach image sensor <NUM>. For a given surface Sk, only optical rays that can form an image on image sensor <NUM> are considered forming a plurality of impact points IP are obtained. CH(Sk) is defined as the distance between two closest possible parallel lines (see lines <NUM> and <NUM> in <FIG> located on a plane P orthogonal to the optical axis of the lens elements (in the representation of <FIG>, plane P is parallel to plane X-Y and is orthogonal to optical axis <NUM>), such that the orthogonal projection IPorth of all impact points IP on plane P is located between the two parallel lines. CH(Sk) can be defined for each surface Sk (front and rear surfaces, with <NUM> ≤ k ≤ 2N).

The definition of CH(Sk) does not depend on the object currently imaged, since it refers to the optical rays that "can" form an image on the image sensor. Thus, even if the currently imaged object is located in a black background which does not produce 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 (for example optical rays emitted by a background which would emit light, contrary to a black background).

For example, <FIG> illustrates the orthogonal projections IPorth,<NUM>, IPorth,<NUM> of two impact points IP<NUM> and IP<NUM> on plane P which is orthogonal to optical axis <NUM>. By way of example, in the representation of <FIG>, surface Sk is convex.

<FIG> illustrates the orthogonal projections IPorth,<NUM>, IPorth,<NUM> of two impact points IP<NUM> and IP<NUM> on plane P. By way of example, in the representation of <FIG>, surface Sk is concave.

In <FIG>, the orthogonal projection IPorth of all impact points IP of a surface Sk on plane P is located between parallel lines <NUM> and <NUM>. CH(Sk) is thus the distance between lines <NUM> and <NUM>.

Attention is drawn to <FIG>. According to the presently disclosed subject matter, a clear aperture CA(Sk) is defined for each given surface Sk (for <NUM> ≤ k ≤ 2N), as the diameter of a circle, wherein the circle is the smallest possible circle located in a plane P orthogonal to the optical axis <NUM> and encircling all orthogonal projections IPorth of all impact points on plane P. As mentioned above with respect to CH(Sk), it is noted that the definition of CA(Sk) also does not depend on the object which is currently imaged.

As shown in <FIG>, the circumscribed orthogonal projection IPorth of all impact points IP on plane P is circle <NUM>. The diameter of this circle <NUM> defines CA(Sk).

Detailed optical data and surface data are given in Tables <NUM>-<NUM> for the example of the lens elements in <FIG>, in Tables <NUM> and <NUM> for the example of the lens elements in <FIG>, in Tables <NUM> and <NUM> for the example of the lens elements in <FIG> and in Tables <NUM> and <NUM> for the example of the lens elements in <FIG> (see below). The values provided for these examples are purely illustrative and according to other examples, other values can be used.

In the tables below, the units of the radius of curvature ("R"), the lens element thickness ("Thickness") and the clear aperture ("CA") are expressed in millimeters.

Line "<NUM>" of Tables <NUM>, <NUM> and <NUM> and <NUM> describes parameters associated to the object (not visible in the figures); the object is being placed at <NUM> from the system, considered to be an infinite distance.

Lines "<NUM>" to "<NUM>" of Tables <NUM> to <NUM> describe respectively parameters associated to surfaces S<NUM> to S<NUM>. Lines "<NUM>" to "<NUM>" of Tables <NUM> to <NUM> describe respectively parameters associated with surfaces S<NUM> to S<NUM>.

Lines "<NUM>", "<NUM>" and "<NUM>" of Tables <NUM> and <NUM>, and lines "<NUM>", "<NUM>" and "<NUM>" in Tables <NUM> and <NUM> describe respectively parameters associated to surfaces 205a, 205b of optical element <NUM> and of a surface 202a of the image sensor <NUM>.

In lines "i" of Tables <NUM>, <NUM> and <NUM> (with i between <NUM> and <NUM> in tables <NUM> and <NUM> and i between <NUM> and <NUM> in Table <NUM>), the thickness corresponds to the distance between surface Si and surface Si+<NUM>, measured along the optical axis <NUM> (which coincides with the Z axis).

In line "<NUM>" of Tables <NUM>, <NUM> (line "<NUM>" in Tables <NUM> and <NUM>), the thickness is equal to zero, since this corresponds to the last surface 202a.

"BK7", "K26R", "EP6000" and "H-ZK3" are conventional materials which are known to a person skilled in the art and which are mentioned by way of example.

"BK7" is characterized by the approximate following parameters:.

"K26R" is a material manufactured by Zeon Corporation, and is characterized by the approximate following parameters:.

"EP6000" is a material manufactured by Mitsubishi, and is characterized by the approximate following parameters:.

"H-ZK3" is a type of glass characterized by the approximate following parameters:.

In Table <NUM>, the properties of each surface material are given, with "Nd" as refractive index and "Vd" as Abbe number.

The equation of the surface profiles of each surface Sk (for k between <NUM> and 2N) is expressed by: <MAT> where "z" is the position of the profile of the surface Sk measured along optical axis <NUM> (coinciding with the Z axis, wherein z = <NUM> corresponds to the intersection of the profile of the surface Sk with the Z axis), "r" is the distance from optical axis <NUM> (measured along an axis which is perpendicular to optical axis <NUM>), "K" is the conic coefficient, c = <NUM>/R where R is the radius of curvature, and An (n from <NUM> to <NUM>) are coefficients given in Tables <NUM> and <NUM> for each surface Sk. The maximum value of r, "max r", is equal to D/<NUM>.

In the example of <FIG> and <FIG>, the following optical properties are achieved:.

In the example of <FIG>, the following optical properties are achieved:.

In this application and for the properties above, the following symbols and abbreviations are used, all of which are terms known in the art:.

The examples provided with reference to <FIG> and <FIG> illustrate a case where CA(S<NUM>) = CH(S<NUM>). In similar cases, CA(S<NUM>) may be substantially equal to CH(S<NUM>), for example with up to <NUM>% difference.

In addition, an "aperture stop" <NUM> (which defines the lens aperture) is located before the first surface S<NUM>. The aperture stop can be e.g. a mechanical piece. A lens module with an aperture stop located at or before the first surface S<NUM> is known in the art as a "front aperture lens". Lens module <NUM> is a front aperture lens.

Note that in other examples, the stop may be located at a different location or surface. In this case, this condition may not be true for the first surface S<NUM>. For example (this example being not limiting), the aperture stop can be located at the second surface S<NUM>. In this case, CA(S<NUM>) = CH(S<NUM>). In similar cases CA(S<NUM>), may be substantially equal to CH(S<NUM>), for example with up to <NUM>% difference.

According to some examples of the presently disclosed subject matter, there is provided an optical lens module comprising a plurality of lens elements where CH(S<NUM>) of surface S<NUM> of lens element L<NUM> (closest to the object side) is greater than CH(Sk) of each of all other surfaces Sk of the plurality of lens elements, with <NUM> ≤ k ≤ 2N.

For example, if N = <NUM> (as in <FIG>,<FIG> and <FIG>), CH(S<NUM>) is greater than CH(S<NUM>), CH(S<NUM>), CH(S<NUM>), CH(S<NUM>), CH(S<NUM>), CH(S<NUM>) and CH(S<NUM>). This applies to different values of N.

For example, if N = <NUM> (as in <FIG>,<FIG> and <FIG>), CH(S<NUM>) is greater than CH(S<NUM>), CH(S<NUM>), CH(S<NUM>), CH(S<NUM>), CH(S<NUM>) and CH(S<NUM>). This applies to different values of N.

For example, if N = <NUM> (as in <FIG>), CH(S<NUM>) is greater than CH(S<NUM>), CH(S<NUM>), CH(S<NUM>), CH(S<NUM>), CH(S<NUM>), CH(S<NUM>), CH(S<NUM>), CH(S<NUM>) and CH(S<NUM>). This applies to different values of N.

For example, if N = <NUM> (as in <FIG>), CH(S<NUM>) is greater than CH(S<NUM>), CH(S<NUM>), CH(S<NUM>), CH(S<NUM>), CH(S<NUM>), CH(S<NUM>), CH(S<NUM>) and CH(S<NUM>). This applies to different values of N.

According to some examples, CH(S<NUM>) ≥ X × CH(S<NUM>), wherein X is any value in the range [<NUM>;<NUM>] (such as X = <NUM> or any other value in this range).

According to some examples, the following conditions are fulfilled:.

According to some examples, the following condition is fulfilled:.

According to some examples, CA(S<NUM>) of surface S<NUM> of lens element L<NUM> is greater than CA(Sk) of each of all other surfaces Sk of the plurality of lens elements, with <NUM> ≤ k ≤ 2N. According to some examples, CA(S<NUM>) of surface S<NUM> of lens element L<NUM> is greater than CA(Sk) with <NUM> ≤ k ≤ 2N.

For example, if N = <NUM> (as in <FIG> and <FIG>), CA(S<NUM>) is greater than CA(S<NUM>), CA(S<NUM>), CA(S<NUM>), CA(S<NUM>), CA(S<NUM>), CA(S<NUM>) and CA(S<NUM>). This applies to different values of N.

According to some examples, CA(S<NUM>) ≥ X × CA(S<NUM>), wherein X is any value in the range [<NUM>;<NUM>] (such as X = <NUM> or any other value in this range).

In some examples, X can be any value in the range [<NUM>;<NUM>], and Y can be any value in the range [<NUM>;<NUM>].

According to some examples, CA(S<NUM>) is substantially equal to CA(S2N) and is greater than CA(Sk) of each of all other surfaces Sk of the plurality of lens elements, with <NUM> ≤ k ≤ 2N-<NUM>. For example, if N = <NUM> (as in <FIG> and <FIG>), CA(S<NUM>) = CA(S<NUM>) is greater than CA(S<NUM>), CA(S<NUM>), CA(S<NUM>), CA(S<NUM>), CA(S<NUM>), CA(S<NUM>), CA(S<NUM>) and CA(S<NUM>). This applies to different values of N. In similar cases CA(S<NUM>) may be substantially equal to CA(S<NUM>), for example with up to <NUM>% difference.

According to some examples, the following condition is fulfilled: <MAT>.

In this equation, X is any value in the range [<NUM>;<NUM>]. According to some examples, X = <NUM> or X=<NUM> where TTL and BFL are defined above.

In <FIG> and <FIG>, the BFL is measured between the center of the surface S<NUM> and the image sensor <NUM>.

In <FIG> and <FIG>, the TTL is measured between the center of the surface Sk and the image sensor <NUM>.

This configuration of the relative values of BFL and TTL as disclosed above can improve the quality of the image formed on the image sensor.

Using a lens element L<NUM> with a front surface that has a greater CH value or CA value with respect to the other surfaces can help to increase the amount of incoming light which can be sensed by the image sensor of the camera or of the Tele sub-camera.

Advantageously, f/# (f-number) can be less than <NUM>.

Advantageously, S<NUM> and\or S<NUM> can be spherical.

Advantageously, the ratio between the last lens element clear aperture CA(S2N) and the sensor diagonal (SD) may be less than <NUM> or <NUM> or <NUM>.

Advantageously, TTL may be smaller than EFL.

According to some examples of the presently disclosed subject matter (tables <NUM>-<NUM>), all lens elements L<NUM> to LN may be made of plastic material. According to some examples of the presently disclosed subject matter (Tables <NUM>-<NUM>), lens element L<NUM> may be made of glass material and all lens elements L<NUM> to LN may be made of plastic material. This is however non-limiting and lens elements L<NUM> to LN may all be made by either plastic or glass material. The selection of lens element material (plastic or glass) is influenced by various optical and mechanical demands. For example, and as known in the art, different materials (glass and/or plastic) have different refractive indexes, glass having typically a higher refractive index selection range than plastic. For example, different materials have different Abbe numbers, glass having typically a higher Abbe number selection range than plastic. An example for <NUM> materials, refractive indexes and Abbe numbers is given above, out of hundreds of materials with corresponding Abbe numbers and refractive indexes available. For example, the surface profiles of plastic lens elements may be approximated by a polynomial with many coefficients (<NUM>-<NUM> in the examples in Tables <NUM>-<NUM>), while surface profiles of glass lens elements can be approximated in a similar way when molded or may be limited to spherical shape when polished (<NUM> coefficient in the examples in Tables <NUM>-<NUM>). This limitation is driven from manufacturing limits known in the art. For example, the minimal thickness of a glass lens element may be smaller than that of a plastic element, as known in the art. For example, glass lens elements may be cut (or diced or sliced) to a non-circular shape, as demonstrated in <FIG>.

In addition to the fact that at least the first lens element can be of increased dimensions in order to increase light impinging on the sensor, according to some examples, the barrel that holds the lens elements has to be mechanically resilient to external stress while striving to maintain the module height (along an axis perpendicular to the optical axis of barrel, which corresponds to axis Y in the figures) as low as possible. This is advantageous for example when it is desired to fit a camera within the limited available space (e.g. thickness) of a computerized device such as a Smartphone.

Examples of an optical lens module which is designed to deal with these contradictory requirements are described with reference to <FIG>, <FIG>, <FIG> and <NUM>-<NUM>. The optical lens module is not limited to the examples described with reference to <FIG>, <FIG>, <FIG> and <NUM>-<NUM>.

In the example illustrated in <FIG>, barrel <NUM> of optical lens module <NUM> comprises a cavity <NUM> surrounded by walls <NUM>. In this example, a first subset of the lens elements is held in cavity <NUM>, and a second subset of the lens elements is located externally to barrel.

In particular, according to the example shown in <FIG>, lens elements L<NUM> to LN are held within cavity <NUM> and lens element L<NUM> is located outside of barrel <NUM> (that is to say that lens element L<NUM> is not within cavity <NUM>). Lens element L<NUM> can be affixed to barrel <NUM>, by any appropriate mechanical link, such as an adhesive material.

In other examples, lens elements L<NUM> to Li (with <NUM>< i <N) are located outside of barrel <NUM> (out of cavity <NUM>), and lens elements Li to LN are held within cavity <NUM>.

In the example of <FIG>, since lens element L<NUM> is located outside of cavity <NUM>, the height HL1 of lens element L<NUM> can be substantially equal to or larger than the height H of barrel <NUM> (measured along the axis Y between external surfaces of opposite walls of barrel <NUM>). Heights HL2 to HLN of lens element L<NUM> to LN can be smaller than the height H of barrel <NUM>. A numerical (non-limiting) example for lens <NUM> may be have the following values: HL1 = <NUM>, HL2 = HL3 = HL4 = <NUM>.

Attention is now drawn to <FIG>, which depicts another example of an optical lens module <NUM>.

In this example, optical lens module <NUM> comprises a barrel <NUM>. Barrel <NUM> comprises a cavity <NUM> circumvented by walls <NUM>. According to the example illustrated in <FIG>, lens elements L<NUM> to LN can be all located within cavity <NUM>.

According to some examples, a height He of cavity <NUM>, measured along an axis orthogonal to optical axis <NUM> (between internal parts <NUM>), is variable along optical axis <NUM>.

In the representation of <FIG>, height He of cavity <NUM> is measured along axis Y. For each position along the Z axis, height He corresponds in this example to the distance between the internal parts <NUM> of walls <NUM> along axis Y. For cases in which the cavity barrel is axial symmetric, He is the internal diameter of the cavity barrel. In the example of <FIG>, cavity height He is variable along axis Z. In other words, He (Z) is not a constant function.

According to some examples, cavity <NUM> comprises a first portion <NUM> in which first lens element L<NUM> is located and a second portion <NUM> in which at least some of the other lens elements (L<NUM> to LN) are located.

According to this example, height HC(Z<NUM>) of first portion <NUM> of cavity <NUM> is greater than height HC(Z<NUM>) of second portion <NUM> of cavity <NUM>. As a consequence, first lens element L<NUM> (which is generally of greater dimensions, as mentioned above) is positioned within first portion <NUM> of cavity <NUM>, and at least some of the other lens elements are positioned within second portion <NUM> of cavity <NUM>.

According to this example, height HC(Z<NUM>) of first portion <NUM> of cavity <NUM> is designed to fit with the height HL1 of first lens element L<NUM>, and height Hc(Z2) of the second portion <NUM> of cavity <NUM> is designed to fit with height HL2, HL3 and HL4 of the other lens element L<NUM> to L<NUM> (in this example, HL2 = HL3 = HL4).

The variable height of cavity <NUM> along optical axis <NUM> can be obtained e.g. by using walls <NUM> with a variable thickness. As shown in <FIG>, walls <NUM> have a thinner thickness in first portion <NUM> than in second portion <NUM>. In other examples, walls <NUM> have a constant thickness but they have a stepped shape.

Various examples (see <FIG> and <NUM>-<NUM>) of an optical lens module comprising a plurality of lens elements L<NUM> to LN will now be described. These optical lens modules can be used in any of the examples of cameras or of optical designs described above. In these examples (see <FIG> and <FIG>), the relationship between the dimensions of the lens elements can be in accordance with any of the examples described above (see e.g. <FIG> and Tables <NUM>-<NUM>) and are thus not described again.

According to some examples, the height of lens element L<NUM> is greater than the height each of lens elements L<NUM> to LN (in the examples of <FIG> and <NUM>-<NUM>). Other relationships can be defined, as already explained above (these definitions can rely e.g. on a relationship between the clear apertures and/or the clear heights of the lens elements).

Attention is now drawn to <FIG>, which depicts an example of an optical lens module <NUM> comprising a plurality of lens elements L<NUM> to LN. In this example, four lens elements L<NUM> to L<NUM> are depicted. In this example, optical lens module <NUM> comprises a barrel <NUM>. Barrel comprises a cavity <NUM> circumvented by walls <NUM>. At least some of lens elements L<NUM> to LN are located within cavity <NUM>.

The lens elements which are within cavity <NUM> have a center which is substantially aligned with optical axis <NUM>. The center of a lens element can be defined as the physical center of the whole lens element (including the optical part and the mechanical part of the lens element, see e.g. in <FIG> wherein the physical center can be located at the center of the total height HL of the lens element), or as the center of only the optical portion of the lens element (see e.g. in <FIG> wherein the optical center can be located at the center of the optical height Hopt of the lens element). Generally, the physical center of the lens element coincides with the center of the optical part (optical center) of the lens element. For an axial symmetric lens element, Hopt is defined as the maximum of clear apertures of front and back surfaces of the respective lens element.

In this example, extremity <NUM> of walls <NUM> is shaped so that extremity <NUM> of walls <NUM> acts a stop for at least a portion of lens element L<NUM>.

In particular, lens element L<NUM> is prevented from moving in the Y-Z plane by extremity <NUM> of the walls acting as a mechanical stop. By choosing an appropriate shape and appropriate dimensions for extremity <NUM> of the walls <NUM>, and likewise shaping a part of lens element L<NUM> to fit the shape of extremity <NUM>, the center of lens element L<NUM> can be substantially aligned with optical axis <NUM>.

In the example of <FIG>, the cross-section of extremity <NUM> of walls <NUM> has a stepped shape.

An extremal portion <NUM> (this portion is part of the thickness of the lens element) of lens element L<NUM> is located within cavity <NUM>. In some examples, extremal portion <NUM> corresponds to the rear surface of lens element L<NUM>.

A main portion <NUM> (this portion is part of the thickness of the lens element) of lens element L<NUM> is located outside of cavity <NUM>. In some examples, a thickness of extremal portion <NUM> measured along optical axis <NUM> is less than a thickness of main portion <NUM> measured along optical axis <NUM>. Extremal portion <NUM> of lens element L<NUM> is blocked between walls <NUM>. In particular, the stepped shape of extremity <NUM> of walls <NUM> is made to match or to fit a part <NUM> of extremal portion <NUM> of lens element L<NUM>, wherein part <NUM> has also a stepped shape in cross-section. As apparent in <FIG>, the stepped shape of extremity <NUM> fits together with the stepped shape of part <NUM> of lens element L<NUM>. Therefore, lens element L<NUM> is prevented from moving in the Y-Z plane, and the center of lens element L<NUM> can be maintained in alignment with optical axis <NUM>.

<FIG> describes another example of an optical lens module. In this example, the cross-section of extremity <NUM> of walls <NUM> has a sloped shape. In particular, extremity <NUM> can be shaped as a chamfer. An extremal portion <NUM> (this portion is considered in the width of the lens element) of lens element L<NUM> is located within a cavity <NUM> of barrel <NUM> of optical lens module <NUM>. In some examples, extremal portion <NUM> corresponds to the rear surface of lens element L<NUM>. A main portion <NUM> (this portion is part of the thickness of the lens element) of lens element L<NUM> is located outside of cavity <NUM>. Extremal portion <NUM> of lens element L<NUM> is prevented from moving in the Y-Z plane by extremity <NUM> of walls <NUM>.

In particular, the sloping shape of extremity <NUM> of walls <NUM> is made to match or to fit a part <NUM> of extremal portion <NUM> of lens element L<NUM>, wherein part <NUM> has also a sloping shape in cross-section. As apparent from <FIG>, the sloping shape of extremity <NUM> fits together with the sloping shape of part <NUM>. Therefore, lens element L<NUM> is prevented from moving in the Y-Z plane, and the center of lens element L<NUM> can be maintained in alignment with optical axis <NUM>.

<FIG> depicts a variant of <FIG>. In this example, a portion <NUM> of lens element L<NUM> is located within cavity. This portion <NUM> can correspond to a main portion of lens element L<NUM> or to the whole lens element L<NUM>. Extremity <NUM> of walls <NUM> has a sloping shape in cross-section, as in the example of <FIG>, but in this example the slope extends further along the side of lens element L<NUM>. A part <NUM> of portion <NUM> is in contact with extremity <NUM> of walls <NUM>, and has also a sloping shape in cross-section, which fits together with the sloping shape of extremity <NUM>. Therefore, portion <NUM> of lens element L<NUM> is prevented from moving in the Y-Z plane.

<FIG> describes another example. In this example, an extremal portion <NUM> (this portion is part of the width of the lens element) of lens element L<NUM> is located within a cavity <NUM>, whereas a main portion <NUM> (this portion is part of the width of the lens element) of lens element L<NUM> is located outside of cavity <NUM>. In some examples, extremal portion <NUM> corresponds to the rear surface of lens element L<NUM>.

In some examples, a thickness of the extremal portion <NUM> measured along optical axis <NUM> is less than a thickness of main portion <NUM> measured along optical axis <NUM>.

Extremal portion <NUM> of lens element L<NUM> is blocked between walls <NUM>. In particular, a part <NUM> of extremal portion <NUM> which is in contact with an extremity <NUM> of walls <NUM> has a stepped shape. Extremity <NUM> of walls <NUM> acts as a stop for extremal portion <NUM>, since part <NUM> is blocked by extremity <NUM> and is prevented from moving in the Y-Z plane. Therefore, lens element L<NUM> is prevented from moving in the Y-Z plane, and the center of lens element L<NUM> can be maintained in alignment with optical axis <NUM>.

In this example, the shape of walls <NUM> can be uniform. In particular, the shape of extremity <NUM> of walls <NUM> can be identical with the shape of the other portions of walls <NUM>, contrary to the examples described in <FIG>, <FIG> and <FIG>, and only a part of the lens element is needed to be shaped in order to fit extremity <NUM>.

According to some variants of the example of <FIG>, a main portion of lens element L<NUM> is located within the cavity (and not only an extremal portion as in <FIG>) and the extremity (see reference <NUM> in <FIG>) of the walls matches a part of lens element L<NUM> which has a stepped shape. Lens element L<NUM> is thus prevented from moving in the Y-Z plane.

According to some examples, an optical lens module <NUM> can comprise lens elements L<NUM> to LN and a barrel <NUM>. Barrel <NUM> comprises a cavity <NUM> surrounded by walls <NUM>. N lens elements L<NUM> to LN are located within cavity <NUM>. In this example, N is equal to four. The optical lens module can further comprise stops <NUM>, which can be present between each of two adjacent lens elements. Stops <NUM> can have an annular shape. These stops <NUM> are useful for maintaining the lens elements at their required position and for maintaining the required distance between the lens elements.

A height of barrel <NUM>, which can be measured, for example, between external surfaces <NUM> of opposite walls <NUM> of barrel <NUM> (e.g. along an axis Y orthogonal to a symmetry axis of barrel <NUM>) is equal to H. In the examples of <FIG>, the height HL1 of lens element L<NUM> can be substantially equal to H or greater than H. Thus, lens element L<NUM> can have a large height (thus benefiting from an increased optical collection surface) while being located within the optical lens module which provides protection and mechanical support of lens element L<NUM>. With this configuration, the center of lens element L<NUM> can be maintained in alignment with optical axis <NUM>.

In addition, a lens element generally has an optical part and a mechanical part. The mechanical part is the part of the lens element which is not used for transmitting rays. This is visible for example in <FIG>, in which lens element L<NUM> comprises an optical part <NUM> and a mechanical part <NUM>. This is also illustrated in <FIG>.

According to some examples, the ratio between a height of the optical part (see Hopt in <FIG>) and the height of the lens element (see HL in <FIG>) is greater for lens element L<NUM> than for each of lens elements L<NUM> to LN.

As shown in the figures, barrel <NUM> can comprise slots <NUM> on two of the opposite walls <NUM> of barrel <NUM>. This allows the lens element L<NUM> to be substantially of the same height as the barrel, or to have a height which is greater than the barrel, and to have a height which is greater than that of the other lens elements. In particular, lens element L<NUM> can be tangent to slots <NUM>, or at least part of the lens element L<NUM> can protrude through slots <NUM>.

Attention is now drawn to <FIG> which describes an example of a manufacturing method of the optical lens module of <FIG>. The method can comprise a step <NUM> of providing a barrel comprising walls defining a cavity. The barrel can already comprise slots on at least two opposite walls. Alternatively, the method can comprise creating slots in at least two opposite walls of the barrel.

The method can comprise a step <NUM> of inserting lens elements L<NUM> to LN in the cavity of the barrel. Generally, lens element LN, which is the closest to the image side, is the first lens element to be inserted. Lens element LN can be fastened to the barrel using a fastening material such as an adhesive, so that it acts as a stop at one side of cavity for the other lens elements.

According to some examples, stops are inserted within cavity, between the lens elements, as already discussed with respect to <FIG>. The lens elements are thus stacked within cavity. In order to prevent the lens elements from moving from their position, the method can comprise a step <NUM> of fastening at least lens element L<NUM> in order to maintain lens elements L<NUM> to LN within cavity. This can be performed by injecting a fastening material (e.g. adhesive) within the cavity, e.g. through adapted through-holes <NUM> present in the walls of the barrel. The adhesive thus fastens lens element L<NUM> to the internal surfaces of the walls. After these steps, and if necessary, the through holes can then be plugged.

The structure of the lens module as depicted in <FIG> is thus also advantageous in terms of the manufacturing process, since lens element L<NUM> can be of the height of barrel (or can have a height which is greater than the height of the barrel) and can still be fastened to the internal surfaces of the walls of the barrel (and not as in <FIG>, where lens element L<NUM> is outside of the barrel and affixed only to an extremity of the walls of the barrel).

Attention is now drawn to <FIG>, which depicts an example of an optical lens module <NUM> comprising a plurality of lens elements <NUM>. Optical lens module <NUM> comprises a barrel <NUM>. At least some of the lens elements can be located within barrel <NUM>.

According to some examples, at least part of the lens elements can have a shape (profile) in cross-section (in plane X-Y, which is orthogonal to the optical lens module and which generally coincides with the optical axis) which is not circular. In particular, as shown e.g. in <FIG>, at least some of the lens elements can have a width WL (measured along axis X) which is greater than their height HL (measured along axis Y). The height HL can correspond to the total height of the lens element (including the mechanical part). In some embodiments, a lens element in lens module <NUM> may have a symmetry about axis Y and/or about axis X.

According to some examples, WL is substantially greater than HL (for example, by at least a percentage which is equal or greater than <NUM>%, these values being not limiting).

According to some examples, at least part of the lens elements is shaped so as their profile in cross-section comprises sides with straight portions. Other sides of the profile can be e.g. curved. This can be seen e.g. in <FIG>, wherein sides <NUM> (in this example two sides) of the profile of these lens elements in cross-section are substantially straight lines along axis X. As a consequence, at least some of the sides of these lens elements are flat surfaces (in plane X-Z). In <FIG>, the two other sides <NUM> of the profile of these lens elements in cross-section are curved lines.

According to some examples, barrel <NUM> is shaped to fit with the shape of the lens elements. Thus, barrel <NUM> can have walls which have a profile in cross-section which is similar to the profile of the lens elements (located in barrel) in cross-section.

It is to be noted that other shapes and profiles can be used for the lens elements (and thus for barrel), such as (but not limited to) an elliptic profile.

The configuration described with reference to <FIG> allows in particular to increase the quantity of light received by the image sensor, for a given height of barrel.

In the example depicted in <FIG>, lens element L<NUM>, which is the closest lens element to the object side, is located outside of barrel <NUM>. Examples wherein lens element L<NUM> is positioned outside of barrel have been described e.g. with reference to <FIG>, and examples wherein a main portion (measured along the thickness of the lens element) of lens element L<NUM> is located outside of barrel <NUM> have been described above (see e.g. <FIG>). At least part of the features described with reference to these examples can be used in the example of <FIG> and are not described again.

In the example depicted in <FIG>, lens element L<NUM>, which is the closest lens element to the object side, is also located within barrel <NUM>. Examples wherein lens element L<NUM> is positioned within the barrel have been described e.g. with reference to <FIG>, and examples wherein a main portion (measured along the thickness of the lens element) of lens element L<NUM> is located within the barrel have been described above (see e.g. the description of <FIG> and <FIG>). At least part of the features described with reference to these examples can be used in the examples of <FIG> and are not described again.

Attention is now drawn to <FIG>. <FIG> shows an isometric view of a lens module <NUM>. <FIG> shows a side view of lens module <NUM>. <FIG> shows an exploded view of lens <NUM>. Lens module <NUM> may have an optical design similar to lens <NUM>. Lens module <NUM> includes a barrel <NUM>. Lens module <NUM> further includes lens elements L<NUM> to LN. N is normally in the range of <NUM>-<NUM>, similar to lens module <NUM>. In the non-limiting example of lens module <NUM>, N=<NUM>. Lens module <NUM> has the first lens element L<NUM> partially positioned or placed outside of barrel <NUM>, while lens elements L<NUM> to LN are placed completely inside the barrel. L<NUM> is clearly seen in <FIG>, while other lens elements are not seen in this view but can be seen in <FIG>. Lens module <NUM> has an optical axis <NUM> which serves as an axial symmetry axis for all lens element L<NUM> to LN. Each lens element Li has a height HLi defined along the Y axis. Lens element L<NUM> may have a "stepped" shape, i.e. it has a front part with height HL1 and a back part with height HL1B, such that HL1 > HL1B. Lens module <NUM> may further include spacers R<NUM> to RN-<NUM>. Each spacer Ri is positioned between lens elements Li and Li+<NUM>. In some embodiments, one or more of spacers R<NUM> to RN-<NUM> may be used as an aperture stop(s).

Barrel <NUM> may be made for example from opaque plastic using plastic injection molding, as known in the art. Barrel <NUM> has a cavity <NUM> that may be axial- symmetric along optical axis <NUM>. Cavity <NUM> may have a shape of cylinder as in embodiment <NUM> (<FIG>). In other embodiments, cavity <NUM> may have other axial symmetric shapes, such as a cone, a series of cylinders, etc. (see <FIG>). The axial symmetry accuracy of cavity <NUM> is important for the assembling accuracy, as known in the art. In some embodiments, the tolerance for axial symmetry distortion may be smaller than <NUM>, <NUM> or <NUM>.

Lens elements Li may be made by plastic injection molding, as known in the art. Lens elements Li may be made from glass, as known in the art. Each lens element Li has front surface (S2i-<NUM>) and back surface (S2i) as defined above for embodiment <NUM>. Each surface Sk (<NUM> ≤ k ≤ 2N) may have an optically active part and a mechanical part which is a non-active optical part (as described in <FIG>). A mechanical part may be used to handle the lens element during the molding and assembly stages. In some examples the mechanical part size may be on the order of <NUM>-<NUM>. For example, the mechanical part of S<NUM> is marked with numeral <NUM>. The closest point of L<NUM> to the object side is marked with numeral <NUM>.

<FIG> shows a lens module <NUM> which is similar to lens module <NUM> with a single difference: barrel <NUM> with cavity <NUM> replaces barrel <NUM> with cavity <NUM>. Cavity <NUM> has a shape of a series of cylinders in increasing sizes for each lens element; as can be seen in <FIG>, HL1B ≤ HL2 ≤ HL3 ≤ HL4<HL1. This feature may allow easier molding of barrel <NUM> and/or easier assembly of lens elements L<NUM> to L<NUM> and spacers R<NUM> to R<NUM>. In other embodiment the number of lens elements may differ from <NUM> as mentioned above. A numerical (non-limiting) example for lens module <NUM> may be have the following values: HL1 = <NUM>, HL1B =<NUM>, HL2 = <NUM>, HL3 = <NUM>, HL4 = <NUM>.

The assembly of lens module <NUM> (or <NUM>) may be done in the following steps:.

Attention is now drawn to <FIG>. <FIG> shows an isometric view of lens module <NUM> which is similar to lens module <NUM>, except that it has an added cover <NUM>. All other parts (barrel, lens elements, optical axis) are as in lens module <NUM> and have the same numbering and names. <FIG> shows a side cut of lens module <NUM>. <FIG> shows an exploded view of lens module <NUM>. Cover <NUM> may be made from opaque plastic, e.g. by plastic injection molding. Cover <NUM> is positioned on top of lens element L<NUM>. In some embodiments, cover <NUM> may optically cover mechanical part <NUM> such that cover <NUM> prevents any optical ray of light arriving from the OPFE from reaching mechanical part <NUM>. In some embodiments, cover <NUM> may have a point <NUM> which is closer to the object than point <NUM> on L<NUM>. This feature is important in order to protect lens module <NUM> while handling and assembling, such that the risk of having lens element L<NUM> touching accidently another object is minimized.

The assembly process of lens module <NUM> may be similar to the assembly process of lens module <NUM> above with an addition of a fifth step:.

Positioning of cover <NUM> and gluing it to barrel <NUM> or to L<NUM>. In one example gluing may be done on surface <NUM>.

Attention is now drawn to <FIG> and <FIG>, which show a lens module <NUM> similar to lens module <NUM>, except that a barrel <NUM> replaces barrel <NUM>. The change to barrel <NUM> allows a different assembly process (relative to lens module <NUM>), detailed below. <FIG> shows a side cut of lens <NUM> and <FIG> shows lens module <NUM> in an exploded view, according to the different assembly direction.

The assembly of lens module <NUM> may be done in the following steps:.

The presently disclosed subject matter also contemplates a method of forming an image on an image sensor, using any of the examples described above.

The presently disclosed subject matter also contemplates a method of producing an optical lens module according to the specifications as described by any of the examples above.

According to some examples, the digital camera can be integrated inside a housing of a mobile electronic device (such as, but not limited to, a smartphone, a portable computer, a watch, eyewear, etc.).

According to some examples, the optical lens module, associated with the lens elements, (as described in the various examples above), can be integrated in a digital camera, or in a Tele sub-camera or in a plurality of Tele sub-cameras of a digital camera. This digital camera can in addition comprise one or more Wide sub-cameras.

A folded camera can be used to reduce the height of elements of the camera. As mentioned above, this can e.g. facilitate the integration of the camera when only limited space is available.

According to at least some of the examples described above, the proposed solution can increase image quality by increasing the incoming light through the camera aperture. This can be achieved notwithstanding an increase of the distance (along Z axis) between the first lens element (at the object side) and the image sensor, as a result of a longer EFL used for obtaining an increased zoom factor.

In addition, according to at least some of the examples described above, the proposed solution can offer an optical lens module which can firmly hold the lens elements while complying with the limited available height.

In addition, according to at least some of the examples described above, the quantity of light which is collected by the sensor is increased for a given height of barrel of the optical lens module.

As explained above, using a lens element L<NUM> incorporated in a lens module (the lens module comprising a plurality of lens elements, each having a front surface and a read surface) with a front surface that has a greater CH (clear height) value or greater CA (clear aperture) value with respect to the other surfaces helps to increase the incoming light which enters the lenses barrel and can be sensed by an image sensor of the camera (e.g. Tele sub-camera in a dual aperture camera). As more light can reach the sensor such configuration enables to increase the focal length of the lens module.

It is known that a negative correlation exists between the focal length and a respective field of view, where the field of view becomes smaller as the focal length increases. Thus, while an increase to a given focal length in a given camera enables to increase image resolution, the higher resolution image is formed on a smaller area of the camera sensor. In other words, when capturing an image of the same object from the same distance with two lenses, one having a focal length longer the other, the lens module with the longer focal length produces on the sensor a smaller image with higher spatial resolution as compared to the one with the shorter focal length. Thus, the advantages of a larger focal length are accompanied with the disadvantage of a smaller size image.

Accordingly, some examples of the presently disclosed subject matter include a digital camera as disclosed above comprising:
N lens elements Li (lens module) having a symmetry along a first optical axis, each lens element comprising a respective front surface S2i-<NUM> and a respective rear surface S2i, where i is between <NUM> and N, and N is equal to or greater than <NUM>; wherein a clear height value of surface S<NUM> or a clear aperture value of surface S1 is greater than a clear height value or a clear aperture value of each of surfaces S<NUM> to S2N;.

The digital camera further comprises an image sensor and a rotating reflecting element or OPFE (such as a mirror or prism). The rotating reflecting element is inclined with respect to the first optical axis, so as to provide a folded optical path between an object and the lens elements and is capable of being rotated around one or two axes.

An example of such rotating reflecting element is disclosed, by way of example in co-owned international patent application <CIT>, which describes an actuator of a digital camera designed to enable the rotation of a reflecting element around two axes. See for example FIG. 1F, <FIG> and <FIG> and the respective description in PCT/IB2017/<NUM> showing the design of an actuator which allows the rotation of a prism around one or two axes.

Rotation of the reflecting element around one or two axes moves the position of the camera FOV, wherein in each position a different portion a scene is captured in an image having the resolution of the digital camera. In this way a plurality of images of adjacent non-overlapping (or partially overlapping) camera FOV are captured and stitched together to form a stitched (also referred to as "composite") image having an overall image area of an FOV greater than digital camera FOV.

In some examples the digital camera can be a folded Tele camera configured to provide a Tele image with a Tele image resolution, the folded Tele camera comprising a Tele image sensor and its Tele lens assembly is characterized with a Tele field of view (FOVT).

According to some examples, the folded Tele camera is integrated in a multiple aperture digital camera comprising at least one additional upright Wide camera configured to provide a Wide image with a Wide image resolution, being smaller than the Tele image resolution, the Wide camera comprising a Wide image sensor and a Wide lens module with a Wide field of view (FOVw); wherein FOVT is smaller than FOVw. Wherein rotation of the rotating reflecting element moves FOVT relative to FOVw.

The description of co-owned international patent applications <CIT> and <CIT>includes a Tele camera with an adjustable Tele field of view. As described in <CIT> and <CIT>, rotation of the reflecting element around one or two axes moves the position of Tele FOV (FOVT) relative to the Wide FOV (FOVw), wherein in each position a different portion a scene (within FOVw) is captured in a "Tele image" with higher resolution. According to some examples, disclosed in <CIT> and <CIT>, a plurality of Tele images of adjacent non-overlapping (or partially overlapping) Tele FOVs are captured and stitched together to form a stitched (also referred to as "composite") Tele image having an overall image area of an FOV greater than FOVT. According to some examples, the stitched Tele image is fused with the Wide image generated by the Wide camera.

According to some examples, the digital camera further comprises or is otherwise operatively connected to a computer processing device, which is configured to control the operation of the digital camera (e.g. camera CPU). The digital camera can comprise a controller operatively connected to the actuator of the rotating reflecting element and configured to control its operation for rotating the rotating reflecting element.

The computer processing device can be responsive to a command requesting an image with a certain zoom factor and control the operation of the digital camera for providing images having the requested zoom. As mentioned in applications <CIT> and <CIT>, in some examples a user interface (executed for example by the computer processing device) can be configured to allow input of user command being indicative of a requested zoom factor. The computer processing device can be configured to process the command and provide appropriate instructions to the digital camera for capturing images having the requested zoom.

In some cases, if the requested zoom factor is a value between the FOVw and FOVT the computer processing device can be configured to cause the actuator of the reflecting element to move the reflecting element (by providing instruction to the controller of the actuator) such that a partial area of the scene corresponding to the requested zoom factor is scanned and a plurality of partially overlapping or non-overlapping Tele images, each having a Tele resolution and covering a portion of the partial area, are captured. The computer processing device can be further configured to stitch the plurality of captured imaged together in order to form a stitched image (composite image) having Tele resolution and an FOV greater than the FOVT of the digital camera. Optionally the stitched image can then be fused with the Wide image.

<FIG> is a schematic illustration of an example of a stitched image generated by capturing and stitching together <NUM> Tele images. In <FIG>,<NUM> denotes FOVw, <NUM> denotes FOVT at the center of FOVw and <NUM> indicates the size of the requested zoom factor. In the illustrated example, four partially overlapping Tele-images (<NUM>) are captured.

Notably, the overall area of the captured Tele-images (<NUM>) is greater than the area of the requested zoom image (<NUM>). The central part of the captured Tele-images is extracted (e.g. by the computer processing device as part of the generation of the stitched image) for generating the stitched image <NUM>. This helps to reduce the effect of image artefacts resulting from transition from an image area covered by one image to an image area covered by a different image.

<FIG> is a schematic illustration of an example of a stitched image generated by capturing and stitching together <NUM> Tele images. <FIG> is a schematic illustration of an example of a stitched image generated by capturing and stitching together <NUM> Tele images. The same principles described with reference to <FIG> apply to <FIG> and <FIG>. Notably, the output image resulting from the stitching can have a different width to height proportion than the single image proportion. For example, as illustrated in <FIG>, a single image can have <NUM>:<NUM> proportion and the output stitched image can have a <NUM>:<NUM> proportion.

It is noted that image stitching per se is well known in the art and therefore it is not explained further in detail.

<FIG> shows another exemplary embodiment of a lens module numbered <NUM> which includes N lens elements Li (where "i" is an integer between <NUM> and N). In the example of <FIG>, N is equal to <NUM>. For example, L<NUM> is made of glass. The description above referring to lens module <NUM> holds also for lens module <NUM>, with the necessary change of N from <NUM> to <NUM>.

In some cases, both the first and last lens elements can be of increased dimensions in order to increase light impinging on the sensor. Examples of an optical lens module which is designed to deal with such a case is given in <FIG>.

<FIG> show another exemplary embodiment of a lens module numbered <NUM> which includes N lens elements Li. In the example of <FIG>, N is equal to <NUM>. Lens module <NUM> has the property of HL1 = HLN. In <FIG>, lens module <NUM> is shown without a lens barrel. <FIG> shows light ray tracing of lens module <NUM> while <FIG> shows only the lens elements for more clarity. In addition, both figures show image sensor <NUM> and optical element <NUM>.

<FIG> shows schematically in a side view an exemplary lens module numbered <NUM> for holding the lens elements of lens module <NUM>. Lens module <NUM> comprises a barrel <NUM> having a cavity <NUM> surrounded by walls <NUM>. In lens module <NUM>, a first subset of the lens elements is held inside the cavity, and a second subset of the lens elements is located externally to (outside) the barrel. Specifically, lens elements L<NUM> to LN-<NUM> are held within cavity <NUM> and lens elements L<NUM> and LN are located outside of barrel <NUM> (i.e. lens elements L<NUM> and LN are not within cavity <NUM>). Lens element L<NUM> and LN can be affixed (fixedly attached) to barrel <NUM> by any appropriate mechanical link, such as an adhesive material.

In lens module <NUM>, since lens elements L<NUM> and LN are located outside of cavity <NUM>, the height HL1 and HLN of, respectively, lens elements L<NUM> and LN can be substantially equal to the height of barrel <NUM> (measured along the axis Y between external surfaces of opposite walls of barrel <NUM>). Heights HL2 to HLN-<NUM> of lens element L<NUM> to LN-<NUM> can be smaller than the height of barrel <NUM>, marked with H. A numerical (non-limiting) example for lens module <NUM> may be have the following values: HL1 = HL5 =<NUM>, HL2 = HL3 = HL4 = <NUM>.

<FIG> is a schematic representation of a side view of another optical lens module numbered <NUM> for holding the lens elements of <FIG>, <FIG>. Lens module <NUM> comprises a barrel <NUM> having a cavity <NUM> surrounded by walls <NUM>. In lens module <NUM>, all the lens elements L<NUM> and LN are held (located) inside the cavity. Exemplarily, in lens module <NUM>, a height He of cavity <NUM>, measured along an axis Y orthogonal to optical axis <NUM>, is variable along optical axis <NUM> (i.e. the Z axis). For each position along the Z axis, cavity height He corresponds in this example to the distance between the internal parts <NUM> of walls <NUM> along axis Y. In other words, Hc(Z) is not a constant function.

According to the example shown, cavity <NUM> comprises a first portion <NUM> in which first lens element L<NUM> is located, a second portion <NUM> in which the other lens elements (L<NUM> to LN-<NUM>) are located and a third portion <NUM> in which last lens element LN is located. According to this example, heights HC(Z<NUM>) of first portion <NUM> and HC(Z<NUM>) of third portion <NUM> are greater than height H(Z<NUM>) of second (middle) portion <NUM>. As a consequence, first lens element L<NUM> and last lens element LN (which are generally of greater dimensions, as mentioned above) are positioned respectively within first portion <NUM> and third portion <NUM> (respectively) of cavity <NUM>, and at least some of the other lens elements are positioned within second portion <NUM> of cavity <NUM>.

According to this example, height HC(Z<NUM>) of first portion <NUM> is designed to fit with the height HL1 of first lens element L<NUM>, height HC(Z<NUM>) of second portion <NUM> is designed to fit with height HL2, HL3 and HL4 of lens elements L<NUM> to L<NUM> (in this example, HL2 = HL3 = HL4) and height HC(Z<NUM>) of third portion <NUM> is designed to fit with the height HL5 of last lens element L<NUM>.

The variable height of cavity <NUM> along optical axis <NUM> can be obtained e.g. by using walls <NUM> with a variable thickness. As shown in <FIG>, walls <NUM> have a thinner thickness in first portion <NUM> and third portion <NUM> than in second portion <NUM>. In other examples, walls <NUM> may have a constant thickness but may have a stepped shape.

<FIG> is a schematic representation of a side view of another exemplary optical lens module numbered <NUM> for holding the lens elements of <FIG>, <FIG>. Lens module <NUM> comprises a barrel <NUM> having a cavity <NUM> surrounded by walls <NUM>. In this example, lens elements L<NUM> to LN-<NUM> are located within cavity <NUM>. Lens elements L<NUM> and LN have a first part located inside cavity <NUM> and a second part located outside of cavity <NUM>; this is similar to lens element L<NUM> of FIG. An edge <NUM> of lens element L<NUM> and an edge <NUM> of lens element LN has a stepped shape. Walls <NUM> align edges <NUM> and <NUM> such that the center of lens elements L<NUM> and LN can be maintained in alignment with optical axis <NUM>.

<FIG> is a schematic representation of an exploded isometric view of another exemplary optical lens module numbered <NUM> having a lens barrel <NUM> and of a plurality of lens elements L<NUM> to LN (in this example N=<NUM>) before their insertion into the barrel. <FIG> depicts a cross-section view of lens module <NUM> along plane Y-Z, <FIG> depicts a cross-section view of lens module <NUM> along plane X-Z, and <FIG> depicts another isometric view of lens module <NUM> after the insertion of the lens elements into the barrel.

Barrel <NUM> comprises a cavity <NUM> surrounded by walls <NUM>. Lens elements L<NUM> to LN are located within cavity <NUM>. Lens module <NUM> may further include spacers R<NUM> to RN-<NUM>. Each spacer Ri is positioned between lens elements Li and Li+<NUM>. In some embodiments, one or more of spacers R<NUM> to RN-<NUM> may be used as an aperture stop(s). Spacers R<NUM> to RN-<NUM> can have an annular shape.

A height H of barrel <NUM> is measured for example between external surfaces of opposite walls <NUM> of barrel <NUM> (e.g. along an axis Y orthogonal to optical axis <NUM>). In the examples of <FIG>, a height HL1 of lens element L<NUM> and a height HLN of lens element LN can be substantially equal to H or greater than H. Thus, lens elements L<NUM> and LN can have a large height (therefore benefiting from an increased optical collection surface) while being located within the optical lens module which provides protection and mechanical support for lens elements L<NUM> and LN. With this configuration, the center of lens elements L<NUM> and LN can be maintained in alignment with optical axis <NUM>.

Similar to <FIG> above, each lens element has an optical part and a mechanical part. According to some examples, the ratio between a height of the optical part (see Hopt in <FIG>) and the height of the lens element (see HL in <FIG>) is greater for lens elements L<NUM> and LN than for each of lens elements L<NUM> to LN-<NUM>.

As shown in the figures, barrel <NUM> can comprise slots <NUM> on the top and bottom wall of barrel <NUM> on its two endings: close to the object side and close to the image side. This allows lens elements L<NUM> and/or LN to be substantially of the same height as the barrel, or to have a height which is greater than the barrel height, and to have a height which is greater than that of the other lens elements. In particular, lens elements L<NUM> and/or LN can be tangent to slots <NUM>, or at least parts of the lens elements L<NUM> and/or LN can protrude through slots <NUM>.

The structure of the lens as depicted in <FIG> is thus also advantageous in terms of the manufacturing process, since lens elements L<NUM> and LN can be of the height of the barrel (or can have a height which is greater than the height of the barrel) and can still be fastened to the internal surfaces of the walls of the barrel.

The assembly of lens module <NUM> may be done using the following steps:.

In one example, holes <NUM> (<FIG>) in barrel <NUM> may be used to insert the glue to fasten lens elements L<NUM> and LN in steps <NUM> and <NUM>.

Attention is now drawn to <FIG>. <FIG> shows an isometric view of another exemplary lens module numbered <NUM>. <FIG> shows a side view of lens module <NUM>. Lens module <NUM> comprises a barrel <NUM> having a cavity <NUM>, and a plurality of lens elements L<NUM> to LN. N is normally in the range of <NUM>-<NUM>. In the non-limiting example of lens <NUM>, N=<NUM>. Lens module <NUM> has the first lens elements L<NUM> and LN partially positioned or placed outside of barrel <NUM>, while lens elements L<NUM> to LN-<NUM> are placed completely inside the barrel. L<NUM> and LN are clearly seen in <FIG>, while other lens elements are not seen in this view but can be seen in <FIG>. As in previous examples, optical axis <NUM> serves as an axial symmetry axis for all lens elements L<NUM> to LN. Each lens element Li has a height HLi defined along the Y axis. Lens elements L<NUM> and LN may have a "stepped" shape, i.e. it has a front part with height HL1 (HLN) and a back part with height HL1B (HLNB), such that HL1 > HL1B and HLN > HLNB. Lens module <NUM> may further include spacers R<NUM> to RN-<NUM>. Each spacer Ri is positioned between lens elements Li and Li+<NUM>. In some embodiments, one or more of spacers R<NUM> to RN-<NUM> may be used as an aperture stop(s). In some embodiments some adjacent lens elements may not have a spacer therebetween.

Cavity <NUM> may be made for example from opaque plastic and may be axial symmetric along optical axis <NUM>, like cavity <NUM> in figures 17A-17E. In an exemplary embodiment, cavity <NUM> may have a shape of cylinder as in embodiment <NUM> (<FIG>). In other exemplary embodiments, cavity <NUM> may have other axial symmetric shapes, such as a cone, a series of cylinders.

<FIG> shows a lens module <NUM> which is similar to lens module <NUM> with a single difference: barrel <NUM> with cavity <NUM> replaces barrel <NUM> with cavity <NUM>. Cavity <NUM> has a shape of a series of cylinders in increasing sizes for each lens element; as can be seen in <FIG>, HL1B ≤ HL2 ≤ HL3 ≤ HL4<HLNB<HL1=HLN. This feature may allow easier molding of barrel <NUM> and/or easier assembly of lens elements L<NUM> to L<NUM> and spacers R<NUM> to R<NUM>. In other embodiments, the number of lens elements may differ from four, as mentioned above.

The assembly of lens module <NUM> (or <NUM>), and in particular the order of lens element insertion into the barrel, may be similar to the assembly steps of lens module <NUM> above (<FIG>).

Attention is now drawn to <FIG> shows an isometric view of a lens module <NUM> which is similar to lens module <NUM>, except that it has an added cover <NUM> similar to cover <NUM> of lens <NUM>, with similar assembly steps.

Claim 1:
A digital camera (<NUM>) comprising:
an optical lens module (<NUM>, <NUM>) that is a front aperture lens module;
the optical lens module (<NUM>, <NUM>) including N ≥ <NUM> lens elements Li having a first optical axis, each lens element comprising a respective front surface S2i-<NUM> and a respective rear surface S2i, the lens
element surfaces marked Sk where <NUM>≤ k ≤ 2N, wherein each lens element surface Sk has a clear aperture value CA(Sk);
an optical path folding element (OPFE) (<NUM>) for providing a folded optical path between an object and the lens elements; an image sensor having a sensor diagonal (SD); characterised in that a clear aperture value CA(S1) of surface S1 is greater than a clear aperture value of each of surfaces S2 to S2N and wherein clear aperture value CA(S1) ≥ <NUM> × CA(Sk), for each surfaces Sk, with <NUM>≤ k ≤ 2N;
and a ratio CA(S2n)/SD between the clear aperture value of a last lens element CA(S2N) and SD is smaller than <NUM>.