Spacer for mitigating stray light, lens module, and digital camera

Abstract

A spacer for mitigating stray light, a lens module and a digital camera, a spacer for separating a first lens element from a second lens element includes the spacer, a lens module including the spacer, and a digital camera including the lens module. The spacer includes at least one contact section along its edge in contact with the first lens element and the second lens element and at least one non-contact section separated from the first lens element. The at least one non-contact section includes an internal inclined surface designed to reduce or mitigate stray light, the present invention can overcome at least one disadvantage of the prior art.

Description

[0001] This application is a divisional application of application number 201980012285.1 (PCT application number PCT / IB2019 / 051643), filed on March 1, 2019, entitled "Design of a spacer for mitigating stray light".

[0002] Cross-references to related applications

[0003] This application relates to and claims priority to U.S. Provisional Patent Application No. 62 / 637,451, filed March 2, 2018, the entire contents of which are expressly incorporated herein by reference. Technical Field

[0004] The topics currently discussed generally involve digital camera lenses, and also include folding digital cameras. Background Technology

[0005] A typical digital camera includes an image sensor (or “sensor”) and a lens (also called a “lens assembly” or “lens module”). The lens forms an image on the sensor. A lens may include multiple lens elements typically assembled in a single lens barrel. Folded cameras (FC) and double-folded cameras (DFC) are known, for example, see, U.S. Patent No. 9,392,188, the entire contents of which are incorporated herein by reference. Summary of the Invention

[0006] Based on some examples of the currently disclosed subject matter, a spacer is provided for separating a first lens element from a second lens element, the spacer including a spacer edge portion having a contact section that contacts the first lens element and the second lens element and a non-contact section that is separated from the first lens element.

[0007] In addition to the features described above, the spacer according to this aspect of the subject matter of this disclosure can optionally include one or more of the following features (a) to (viii) in any technically possible combination or substitution:

[0008] (i) The non-contact segment includes an internal inclined surface of the non-contact segment, the height (D2) of the internal inclined surface of the non-contact segment extends between an internal contour of the spacer and a base of the internal inclined surface of the non-contact segment, the thickness (t) of the edge portion of the spacer extends between a contact point of the spacer facing a rear surface of the spacer facing the second lens element and a contact point of the spacer facing a front surface of the spacer facing the first lens element, and wherein the inclination of the internal inclined surface of the non-contact segment is greater than the height (D2) / the thickness (t).

[0009] (ii) The height (D2) is perpendicular to the thickness (t).

[0010] (iii) The contact section includes an internal inclined surface of the contact section, and the inclination of the internal inclined surface of the contact section is less than the inclination of the internal inclined surface of the non-contact section.

[0011] (iv) The first lens element is located on an object side relative to the spacer, and the second lens element is located on an image side relative to the spacer.

[0012] (v) An optical component of the first lens element or the second lens element is non-circular.

[0013] (vi) The spacer is included in a camera having an image sensor, and the inclined surface inside the non-contact section is designed to redirect stray light so that stray light does not hit the image sensor.

[0014] (vii) The sensor is characterized in that it has at least two sides, each side having a different length.

[0015] (viii) The sensor is characterized by being non-circular.

[0016] Based on some examples of the currently disclosed subject matter, a lens module is provided, comprising a plurality of lens elements arranged along a lens axis of symmetry from an object side to an image side; and a spacer located between one of the plurality of lens elements and a series of lens elements, the spacer including, along an edge portion of the spacer, a contact section that contacts a first lens element and a second lens element, and a non-contact section separated from the first lens element. The spacer in the lens module can include one or more of the features (a) to (viii) above in any technically possible combination or arrangement.

[0017] Based on some examples of the currently disclosed subject matter, a digital camera is provided, including a lens module housing a plurality of lens elements arranged along a lens symmetry axis from an object side to an image side, and at least one spacer located between one lens element and a series of lens elements, the spacer including a spacer edge portion comprising a contact section that contacts a first lens element and a second lens element, and a non-contact section separated from the first lens element. The spacer in the digital camera can include one or more of the features (a) to (viii) above in any technically possible combination or arrangement. Attached Figure Description

[0018] Non-limiting examples are described below with reference to the accompanying drawings listed after this paragraph. Identical structures, elements, or parts appearing in multiple drawings are generally labeled with the same numerals in all appearing drawings. The drawings and descriptions are intended to illustrate and explain examples of the subject matter disclosed herein and should not be construed as limiting in any way. In the drawings:

[0019] Figure 1A A lens is schematically shown in a typical isometric drawing.

[0020] Figure 1B The present invention illustrates a subject example passing through a container... Figure 1A A cut in the lens barrel, and a stray light path through the lens barrel to an image sensor.

[0021] Figure 1C The display is separated by a spacer, as shown below. Figure 1A The first object-side lens element and the second object-side lens element of the lens.

[0022] Figure 1D Display as shown Figure 1B The spacer has (a) a front surface on the object side and (b) a rear surface on the image side.

[0023] Figure 2A The schematic diagram shows an isometric view of a lens according to an example of the invention.

[0024] Figure 2B The present invention illustrates a subject example passing through a container... Figure 2A A cut in the lens barrel, and a stray light path through the lens barrel to an image sensor.

[0025] Figure 2C The subject matter example shown according to the present invention is separated by a spacer, as shown below. Figure 2A The first object-side lens element and the second object-side lens element of the lens.

[0026] Figure 2DExamples of the subject matter according to the present invention are shown as follows: Figure 2B The spacer has (a) a front surface on the object side and (b) a rear surface on the image side. Detailed Implementation

[0027] In the following detailed description, numerous specific details are set forth in order to provide a clear understanding. However, those skilled in the art will appreciate 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.

[0028] It should be understood that, for clarity, certain features of the subject matter described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, for brevity, various features of the subject matter described in the context of a single embodiment may also be provided individually or in any suitable sub-combination.

[0029] It should be understood that, unless otherwise expressly stated, terms such as “first,” “second,” and “third” used herein do not necessarily imply a specific order, but merely signify the distinction between different elements or actions. For example, the first lens element and the second lens element used herein do not necessarily refer to the pair of lens elements closest to the object side in lens 100 disclosed below, and “lens” can refer to a pair of different lens elements located elsewhere in lens 100, such as the second and third lens elements.

[0030] Stray light is a non-ideal effect of light in an optical system. Stray light is light that is not intended to enter the optical system according to the optical design but still reaches the sensor. In some cases, stray light may originate from a intended light source (e.g., light reflected from an object in the camera's field of view) but follow a path other than the intended one (an optical path that does not pass through the optical areas of all lens elements in the lens module on its way to the sensor). In other cases, stray light may originate from sources other than the intended source (e.g., outside the camera's field of view (FOV)).

[0031] For example, Figure 1B The camera 150 is shown schematically, including a lens (in... Figure 1A (As shown in the figure below, designated 100), the lens 100 has stray light 220 reflected from an internal spacer R1 onto an image sensor 104 (as described in more detail below). Figure 1A Lens 100 is shown in a large isometric view. Lens 100 includes a plurality of (N) lens elements L i (Where "i" is an integer between 1 and N), shown in a decomposed diagram, where different lens elements are displayed. L1 is the lens element closest to the object side, L... NThe lens element is the one closest to the image side, i.e., the side where the image sensor is located, with 100N = 5 in the lens. 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 3. For example, N can be equal to 3, 4, 5, 6, or 7. The XYZ coordinates apply to all other unlabeled views. The lens element is positioned along the optical axis 108, which is aligned with the Z-axis of the sensor from the object side to the image side.

[0032] Each lens element L i Including the corresponding front surface S 2i-1 (Index "2i-1" represents the number of the front surface) and the corresponding rear surface S 2i (index "2") i "N" represents the number of rear surfaces, where "i" is an integer between 1 and N. This numbering is used throughout the description. Alternatively, as noted throughout this specification, lens surfaces are marked "S". k ", where k ranges from 1 to 2N. In some cases, the front and rear surfaces can be aspherical. However, this is not limiting. Figure 1A As shown, in some examples, the optical portion of the first lens element L1 (i.e., the portion through which light passes toward the sensor) is non-circular, for example, non-circular, with a flat top and bottom.

[0033] Figure 1B This is a cross-sectional side view of camera 150. Camera 150 includes a lens barrel 102, within which lens element Li and spacer Ri of lens 100 are located. Camera 150 also includes an image sensor 104 and optional optical elements 106 (e.g., an infrared filter). In the example shown, two adjacent lens elements are labeled "R". I The lens elements L1 and L2 are separated by spacer R1, L2 and L3 are separated by spacer R2, L3 and L4 are separated by spacer R3, and L4 and L5 are separated by spacer R4.

[0034] As used herein, the term "front surface" for each lens element or spacer refers to the location of the lens element or spacer closer to the camera entrance (camera object side), and the term "rear surface" refers to the surface of the lens element or spacer closer to the image sensor (camera image side).

[0035] Figure 1C Showing an enlarged view of lens elements L1 and L2 separated by spacer R1, and Figure 2DThe display shows a front view (object side) and a rear view (image side) of the spacer R1. Each spacer is designed with a periphery and an opening at its center to allow light to pass through and move toward the sensor. The periphery may contact a first lens on one side and a second lens on the other side. The use of such spacers in a lens assembly is known in the art.

[0036] Reference Figures 1B to 2B An example of a lens design that may produce stray light is described. Stray light 120 in camera 150 can arrive, for example, from reflection from the inner surface of spacer R1 (facing an internal opening 118), and therefore depends on the shape of spacer R1 (particularly the shape of its inner surface). In the example shown, when assembled in the lens barrel, the rear surface S2 of lens element L1 contacts spacer R1 over the entire front contact surface 110 of spacer R1 (including bottom and top front surface contact sections 110a and 110b). The front surface S3 of lens element L2 contacts spacer R1 over the entire rear surface contact surface 112 of spacer R1, including bottom and top rear surface contact portions 112a and 112b. Along the Z-axis, the distance between the contact points of the front contact surface 110a and the rear contact surface 112a defines the spacer thickness t, which is denoted as t1 for spacer R1.

[0037] The inner surface 114 of the spacer R1 between the edge 114a of the front contact section 110a and the edge 114b of the rear contact section 112a has a length D3 and an inclination (angle) α, and the spacer R1 has a rear contact section 112a (also as Figure 1B The height D2 (which is substantially perpendicular to the thickness t1) extends between the inner contours of the spacer (as shown) at the edge of the inner opening 118, such as Figure 1D As indicated by arrow 115a in the diagram, the bottom 115 of the inclined surface (indicated by arrow 115b) is provided with an inclination (angle) α. In some cases, the spacer R1 may also have a thickness D1 of a front bottom contact section 110a, which extends from the base 115 of the spacer along the X direction toward the outer edge of the spacer (indicated by arrow 115c). It is worth noting that a similar surface 114, along with thickness D1 and height D2, exists at the top of the spacer R1 (i.e., the lens is radially symmetrical along the X axis). In other examples, other or additional inclined surfaces similar to 114 may exist at other locations around the periphery of the spacer. As described above, the inclination angle α is determined by the thickness t1 and height D2 of the spacer, where

[0038] Based on the example shown, the design of the first lens element L1 and angle α is given and displayed. Figure 1BStray light rays 120 entering the lens from the object side are refracted by the lens element L1, incident on the surface 114 of the spacer R1, reflected from the surface, and continuously pass through the lens along the light path, terminating at point 122 at the image sensor 104.

[0039] Based on the subject matter disclosed in this article, it is suggested that the aforementioned stray light problem be addressed through a special spacer design for this purpose. (See also...) Figures 2A to 2D Describe an example of spacer design. Figure 2A Lens 200, an example according to the subject matter of this disclosure, is schematically shown in a large axonometric view. Lens 200 is shown in an exploded view, in which the different lens elements are shown separately. Figure 2B The first object-side lens element and the second object-side lens element of the lens 200 are shown, separated by the spacer R1'. Figure 2C A side view showing a cross-section of camera 250. Lens 250 includes a lens barrel 202 that houses lens 200. Camera 250 also includes an image sensor 104 and optional optical elements 106 (e.g., an IR filter). Figure 2C It also shows stray light rays 220 passing through the lens tube along the side of the object. Figure 2D Shown on (a) a front surface of the object, and Figure 2B (b) shows a rear surface on the image side.

[0040] For example, lens 200 shows five lenses, similar to lens 100. As mentioned above, the example is not intended to be limiting, and different / more elements are equally conceivable. According to one example, all elements of lens 200 are similar to those of lens 100, except for the "improved" first spacer R1' located between lens elements L1 and L2. Spacer R1' has a steeper inner surface (slope) 214 with a tilt angle α' greater than α, for example, angle α' = 33.3° compared to an angle α equal to approximately 20°. In some examples, a steeper tilt is achieved by shortening the length between edges 214a and 214b (compared to 114a and 114b above), resulting in tilt angle D3'. In some examples, height D2 is the same as the height of spacer R1. It is worth noting that increasing the tilt angle by increasing height D2 can have adverse effects, as this reduces the open space at the center (opening 118) of the spacer, thereby increasing the obstruction of light passing through the lens.

[0041] Unlike lens 100 described above, the contact between S2 and R1 occurs across the entire front contact surface 110, where the shorter length of D3' (relative to D3) causes non-contact sections in R1' (e.g., the bottom and top) to separate from the surface S2 of lens L1 (i.e., contact sections 110a and 110b are shown in the isolator R1). The contact sections 210a and 210b that contact S2 are located near the non-contact sections. By disallowing contact between isolator R1' and S2 in certain sections of the isolator, the tilt angle can be increased. According to the proposed design, the tilt angle of the inner tilted surface is greater than the ratio between height D2 and thickness t1, making... Because the inner bottom surface 214 is steeper, stray light 220 entering the lens from the object side is refracted by the lens element L1, hits the surface 214 of the spacer R1', and the lens passes continuously through the lens along the light path that misses the image sensor 104.

[0042] As mentioned above, the changes to lens 200, especially the changes to spacer R1', bring significant design flexibility. For example, the increased tilt of surface 214 reduces stray light.

[0043] Examples of surface 214 serving as the bottom and / or top surface of R1' are not limited in any way: one, two, or more such surfaces may be formed around the spacer R1', such as facing surface S2. In one embodiment (not shown), surface S2 may contact only at three points on the front contact surface of spacer R1', such that most of the side edges include non-contact surfaces (with greater inclination), such as surface 214.

[0044] It should be noted that although the above description relates to non-circular lens elements (having flat top and / or bottom portions), this should not be construed as limiting. According to other examples, lens elements can be circular, where the lens and / or camera including such a circular lens element still benefit from stray light reduction due to the spacer design disclosed herein. The subject matter of this disclosure can be used to mitigate stray light problems that exist in one or more portions of the periphery of the spacer.

[0045] As described above, stray light entering the lens from the object side is refracted by lens element L1, incident on a portion of the spacer surface, and continues along the light path toward the sensor through the lens.

[0046] For example, consider a sensor characterized by a rectangle. Due to the shape difference between the sensor and the lens (having a circular or nearly circular shape), stray light can hit the sensor when reflected from one side of the spacer, and may miss the sensor when reflected from the other side of the spacer. This difference is also encountered when the sensor is characterized by sides with different lengths, such as in the case of a non-square rectangular sensor.

[0047] The spacer (e.g., R1' located between lens elements L1 and L2) can be adjusted as described above to have a steeper, inclined inner surface 214 on the side of the spacer, which reflects stray light so that it does not touch the sensor. As described above, a higher inclination can be achieved by shortening the length between edges 214a and 214b and obtaining a non-contact portion D3'.

[0048] It should be noted that the digital cameras (150, 250) discussed above can be multi-aperture cameras including one or more additional upright cameras and one or more folding cameras. The folding camera includes a reflective element (e.g., a mirror or prism) configured such that folded light travels along a first optical path from the object side to a second optical path (substantially perpendicular to the first optical path) along the lens axis of symmetry toward the sensor. Examples of folding cameras are described in U.S. Patent No. 9,392,188, which is incorporated herein by reference in its entirety.

[0049] Although this disclosure has been described according to certain embodiments and generally related methods, variations and substitutions of the embodiments and methods will be apparent to those skilled in the art. It should be understood that this disclosure is not limited to the specific embodiments described herein, but only to the scope of the appended claims.

[0050] Unless otherwise stated, the expression "and / or" is used between the last two members of the selection list to indicate that it is appropriate and possible to select one or more of the listed options.

[0051] All references mentioned in this specification are incorporated herein by reference in their entirety, as if each individual reference were specifically and individually indicated to be incorporated herein by reference. Furthermore, any reference or designation of any reference in this application should not be construed as an admission that the reference is prior art to this application.

Claims

1. A spacer for separating a non-circular first lens element from a second lens element, said spacer comprising: A spacer edge portion includes a contact section that contacts the first lens element and the second lens element, and a non-contact section that is separated from the first lens element; The non-contact segment includes an internal inclined surface of the non-contact segment, the internal inclined surface of the non-contact segment having a height D2 and extending between an internal contour of the spacer and a base of the internal inclined surface of the non-contact segment; The spacer edge has a thickness t and extends between a contact point of the spacer facing a rear surface of the second lens element and a contact point of the spacer facing a front surface of the first lens element; The inclination of the inclined surface inside the non-contact section is greater than the height D2 / thickness t.

2. The spacer as claimed in claim 1, wherein: The height D2 is perpendicular to the thickness t.

3. The spacer as claimed in claim 2, wherein: The contact section includes an internal inclined surface, the inclined surface of which has a smaller inclination than the inclined surface of the non-contact section.

4. The spacer as claimed in claim 1, wherein: The first lens element is positioned on an object side relative to the spacer, and the second lens element is positioned on an image side relative to the spacer.

5. The spacer as claimed in claim 1, wherein: An optical component of the first lens element or the second lens element is non-circular.

6. The spacer as claimed in claim 1, wherein: The spacer is included in a camera having an image sensor, and the inclined surface inside the non-contact section is designed to redirect stray light so that it does not hit the image sensor.

7. The spacer as claimed in claim 6, wherein: The sensor is characterized by having at least two sides, each side having a different length.

8. The spacer as claimed in claim 6, wherein: The sensor is characterized by being non-circular.

9. A lens module, comprising: Multiple lens elements are arranged along a lens axis of symmetry from an object side to an image side; and A spacer is located between one lens element and a series of lens elements in the plurality of lens elements. The spacer includes, along its edge, a contact section that contacts a first lens element and a second lens element, and a non-contact section that is separated from the first lens element. The non-contact segment includes an internal inclined surface, the internal inclined surface having a height D2 and extending between an internal contour of the spacer and a base of the internal inclined surface, the edge of the spacer having a thickness t and extending between a contact point of the spacer facing a rear surface of the second lens element and a contact point of the spacer facing a front surface of the first lens element, wherein the inclination of the internal inclined surface of the non-contact segment is greater than the height D2 / the thickness t, and wherein the height D2 is perpendicular to the thickness t.

10. A digital camera, comprising: A lens module includes a plurality of lens elements arranged along a lens axis of symmetry from an object side to an image side, and at least one spacer between one lens element and a series of lens elements, the spacer including a spacer edge portion, the spacer edge portion including a contact section that contacts the lens element and the series of lens elements, and a non-contact section that is separated from the lens elements. The non-contact segment includes an internal inclined surface of the non-contact segment, the internal inclined surface of the non-contact segment having a height D2 and extending between an internal contour of the spacer and a base of the internal inclined surface of the non-contact segment, the edge portion of the spacer having a thickness t extending between a contact point of the spacer facing a rear surface of the continuous lens element and a contact point of the spacer facing a front surface of the lens element, and wherein the inclination of the internal inclined surface of the non-contact segment is greater than the height D2 / the thickness t.

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