Adaptable reflector for an optical illumination system technical field

Abstract

An adaptable reflector (1) for an optical illumination system (2), said reflector (1) comprising a disc (3). A discontinuity (4) extends from an edge of said disc (3) towards an interior of said disc (3), said discontinuity (4) allowing said disc (3) to adopt a first shape (S1) and a second shape (S2). The disc (3) is configured to reflect light rays towards a first image area (A1) when in said first shape (S1) and to reflect light rays towards a second image area (A2) when in said second shape, said first image area (A1) being larger than said second image area (A2). The first shape (S1) facilitates reflection across a wide field of view and said second shape (S2) facilitates reflection across a narrow field of view. The disc (3) may be annular and the discontinuity (4) may be an annulus sector removed from said annular disc (3).

Description

[0001] ADAPTABLE REFLECTOR FOR AN OPTICAL ILLUMINATION SYSTEM

[0002] TECHNICAL FIELD

[0003] The disclosure relates to a reflector for an optical illumination system, as well as an optical illumination system comprising the reflector.

[0004] BACKGROUND

[0005] Mobile phones and their optical systems, i.e. cameras, are developing fast, and are now capable of taking images of objects from far larger distances than before, e.g. by using zoom with zoom factors such as 5x or lOx.

[0006] However, the flash used for these cameras usually comprises basic LEDs that are capable of illuminating only nearby objects with a rather wide cover. When the environment is dark, objects that are not close to the flash remain dark even if the camera itself would be able to capture an image of the object. If the flash instead were to be optimized for further away objects with a smaller field of view, it would be unusable in near-distance photography as the center of the image would be over-lit and the edges would stay dark.

[0007] Adjustable flash is used in ordinary digital cameras, but not much in mobile phones. This is because adjustable flash requires optics with movable lenses, and phone manufacturers today are unwilling to fit such optics in their mobile phones since it takes up a lot of space that could be used for other essential components instead (such as battery).

[0008] Some phone models are provided with an LED array where the individual LED can be driven to create a suitable cone for wide-angle cameras or telecameras, however, when increasing the number of flashes, the required space for flashes increases as does the required battery power.

[0009] Hence, there is a need to provide an improved and adaptable optical illumination system. SUMMARY

[0010] It is an object to provide an improved and adaptable optical illumination system. The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description, and the figures.

[0011] According to a first aspect, there is provided an adaptable reflector for an optical illumination system, the reflector comprising a disc, a discontinuity extending from an edge of the disc towards an interior of the disc, the discontinuity allowing the disc to adopt a first shape and a second shape, the disc being configured to reflect light rays towards a first image area when in the first shape and to reflect light rays towards a second image area when in the second shape, the first image area being larger than the second image area.

[0012] This solution allows the light emitted by a light source, e.g. a flash, to be adapted to cover differently sized image areas, allowing the illumination provided by the light source to be adapted to different environmental conditions and distances to objects.

[0013] In a possible implementation form of the first aspect, the first shape facilitates reflection across a wide field of view and the second shape facilitates reflection across a narrow field of view. This allows reflected light to be matched to the actual field of view and battery consumption to be kept at a minimum.

[0014] In a further possible implementation form of the first aspect, the disc is annular, and the discontinuity extends radially from an inner circumference of the annular disc to an outer circumference of the annular disc. This allows a reflector that can be arranged around e.g. camera module optics, that provides a symmetric light field, is easy and inexpensive to manufacture, and allows a stepless and continuous adaptation of the illumination to fit the current size of the image area.

[0015] In a further possible implementation form of the first aspect, the discontinuity forms a gap in the disc, the gap being delimited by a first disc edge and a second disc edge. This facilitates a reflector that can change shape by simply curving or bending the reflector. The reflector can be made of e.g. sheet metal since no stretching is required. In a further possible implementation form of the first aspect, the discontinuity is formed by a throughgoing slit or by a section of the disc being removed. This allows a simple and cost- effective manufacturing process while facilitating illumination of a large range of fields of view.

[0016] In a further possible implementation form of the first aspect, the first disc edge and the second disc edge extend adjacent each other when the disc has adopted the second shape. This allows the reflector to be held firmly and stably in the second shape.

[0017] In a further possible implementation form of the first aspect, the first disc edge and the second disc edge overlap a surface of the disc when the disc has adopted the second shape. This allows a larger range of fields of view.

[0018] In a further possible implementation form of the first aspect, the discontinuity comprises resilient material. This allows the reflector to adopt different shapes, or be held in a specific shape, without requiring separate components.

[0019] In a further possible implementation form of the first aspect, the adaptable reflector further comprises a resilient element attached to a surface of the disc on opposite sides of the discontinuity, the resilient element being configured to move the disc between the first shape and the second shape and / or to maintain the disc in the first shape and / or the second shape. Hence, the actuator moving the disc between different shapes can be part of the reflector itself. In a further possible implementation form of the first aspect, the first shape is planar and the second shape is non-planar. This allows a reflector that takes up as little space as possible while still allowing a large range of field of views.

[0020] In a further possible implementation form of the first aspect, at least one surface of the disc comprises a reflective coating and / or a surface profile. This facilitates different qualities such as ease of manufacture, thickness reduction, and / or illumination in different directions.

[0021] According to a second aspect, there is provided an optical illumination system comprising the adaptable reflector according to the above, at least one light source, a base element configured to carry the adaptable reflector, and a movable element configured to generate movement of the adaptable reflector between the first shape and the second shape and / or to maintain the adaptable reflector in the first shape and / or the second shape. This facilitates optimum illumination to be achieved using only a small number of components having small form factors and that do not require much battery power. The illumination would be even and wide enough to allow wide-angle photography, while also being able to focus the light from the light source(s) to a narrow beam capable of illuminating targets further away.

[0022] In a possible implementation form of the second aspect, the reflector is fixed to the base element such that a first section of the disc is immobile in directions along an optical axis of the optical illumination system, and a second section of the disc is moveable in directions along the optical axis. This facilitates an adaptable yet still simple and size-effective illumination system.

[0023] In a further possible implementation form of the second aspect, the movable element comprises a sleeve and a cover configured to engage a surface of the sleeve, a void between the sleeve and the cover accommodates at least a part of the second section of the disc such that movement of the movable element along the optical axis generates movement of the second section and movement of the disc between the first shape and the second shape. This allows a continuous change in the shape of the reflector without the need for separate components.

[0024] In a further possible implementation form of the second aspect, a first thread arranged on the base element is configured to engage a second thread arranged on the moveable element, and one of the base element and the moveable element comprises at least one protrusion and the other of the base element and the moveable element comprises at least one groove configured to receive the protrusion(s), the groove(s) extending in parallel with the optical axis such that rotational movement of one of the base element and the moveable element is transformed to linear movement of the other of the base element and the movable element along the optical axis. This type of actuation has a small form factor while still allowing a large range of fields of view.

[0025] According to a third aspect, there is provided an electronic apparatus comprising the optical illumination system according to the above. This allows optimum illumination to be achieved while freeing up space within the electronic apparatus for other components.

[0026] These and other aspects will be apparent from the embodiments described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In the following detailed portion of the present disclosure, the aspects, embodiments and implementations will be explained in more detail with reference to the example embodiments shown in the drawings, in which:

[0028] Fig. 1 shows an exploded view of an optical illumination system in accordance with an example of the embodiments of the disclosure;

[0029] Figs. 2a and 2b show cross-sectional side views of an optical illumination system in accordance with an example of the embodiments of the disclosure, wherein the reflector has adopted a first shape and a second shape, respectively;

[0030] Fig. 3 shows a cross-sectional side view of an optical illumination system in accordance with an example of the embodiments of the disclosure, wherein the reflector has adopted the second shape;

[0031] Fig. 4a and 4b show perspective views of an adaptable reflector in accordance with an example of the embodiments of the disclosure, wherein the reflector has adopted the first shape and the second shape, respectively;

[0032] Figs. 5 to 7 show perspective views of adaptable reflectors in accordance with examples of the embodiments of the disclosure;

[0033] Fig. 9 shows a perspective view of a part of an optical illumination system in accordance with an example of the embodiments of the disclosure;

[0034] Figs. 10a and 10b show cross-sectional side views of an optical illumination system in accordance with an example of the embodiments of the disclosure, wherein the reflector has adopted a first shape and a second shape, respectively. DETAILED DESCRIPTION

[0035] The present invention relates to an adaptable reflector 1 for an optical illumination system 2, the reflector 1 comprising a disc 3, a discontinuity 4 extending from an edge of the disc 3 towards an interior of the disc 3, the discontinuity 4 allowing the disc 3 to adopt a first shape SI and a second shape S2, the disc 3 being configured to reflect light rays towards a first image area Al when in the first shape SI and to reflect light rays towards a second image area A2 when in the second shape, the first image area Al being larger than the second image area A2.

[0036] The optical illumination system 2 is described in more detail further below.

[0037] The adaptable reflector 1 comprises a disc 3, i.e. a substantially flat or planar element that has a significantly smaller thickness than width and length, such as a disc made of a sheet of metal or other material made to be reflective by means of polishing, coating, etc.

[0038] A discontinuity 4 extends from an edge of the disc 3 towards an interior of the disc 3. The discontinuity 4 is configured such that it allows the disc 3 to adopt a first shape SI and a second shape S2. 9. The first shape SI may be planar, for example completely planar or substantially planar, and the second shape S2 may be non-planar, for example turning the disc into a truncated cone as shown in Figs. 2b, 3, 5, 9, and 10b.

[0039] The disc 3 is configured to reflect light rays towards a first image area Al when in the first shape SI and to reflect light rays towards a second image area A2 when in the second shape. The first image area Al is larger than the second image area A2. In other words, the first shape SI facilitates reflection across a wider field of view and the second shape S2 facilitates reflection across a narrower field of view. This is illustrated in Figs. 10a and 10b, Fig. 10a showing the first shape SI, the first image area Al, and a relatively wide field of view and Fig. 10b showing the second shape S2, the second image area A2, and a relatively narrow field of view.

[0040] As shown in Figs. 1, 2, 4a to 7, and 9, the disc 3 may be substantially annular. The discontinuity 4 extends radially from an inner circumference 5 of the annular disc 3 to an outer circumference The discontinuity 4 may form a gap in the disc 3, the gap being delimited by a first disc edge 7 and a second disc edge 8.

[0041] The discontinuity or gap 4 may be formed by a throughgoing slit, as illustrated in Fig. 5, or by a section of the disc 3 being removed, as illustrated in Figs. 1, 4a, 4b, 6, 7, and 9. The gap may, in other words, be an annulus sector removed from the annulus shaped disc 3. In the case of an annular disc 3, the first disc edge 7 and the second disc edge 8 may extend radially, see in particular Figs. 4a to 7.

[0042] As illustrated in Fig. 4b, the first disc edge 7 and the second disc edge 8 may extend adjacent each other when the disc 3 has adopted the second shape S2, such that the disc 3 forms a substantially continuous reflective surface.

[0043] As illustrated in Fig. 5, the first disc edge 7 and the second disc edge 8 may instead overlap a surface 9 of the disc 3 when the disc 3 has adopted the second shape S2, allowing a wider range of disc motion. The more overlap is applied, the steeper the cone angle of the disc 3 becomes.

[0044] The above-mentioned types of discontinuities 4 allow the reflector 1 to be only bent or curved in order to change shape. Since there is no need for stretching the reflector, the disc 3 may be made of a delicate material such as paper. However, the discontinuity 4 may instead comprise a resilient material, for example by filling the above-mentioned gap 4 with resilient material instead of the gap just being an air gap as shown in the Figures.

[0045] As illustrated in Fig. 7, the adaptable reflector 1 may further comprise a resilient element 10 attached to a surface 9 of the disc 3 on opposite sides of the discontinuity 4. The resilient element 10 is configured to move the disc 3 between the first shape SI and the second shape S2 and / or to maintain the disc 3 in the first shape SI and / or the second shape S2, i.e. to act as an actuator. The resilient element 10 may be an SMA (shape memory alloy) spring, however, any other suitable type of actuator such as a piezo actuator or voice coil magnet actuator may be used.

[0046] At least one surface 9 of the disc 3 may comprise a reflective coating such as a silver coating (not shown) and / or a surface profile such as that shown in Fig. 6. The surface 9 profile may in other words be straight / flat or have a surface profile that is curved or of a ribbed Fresnel-type for achieving maximum mirroring angles. Hence, the disc 3 may have a generally planar shape while the individual surface(s) 9 of the disc 3 may be non-planar, e.g. undulating.

[0047] The present invention also relates to an optical illumination system 2 comprising the adaptable reflector 1 and at least one light source 11. The light source 11 may be arranged at the center of the disc, for an annular disc the light source 11 may be arranged coaxially with a center axis of the annulus as illustrated in Figs. 1 to 3, 7, and 9 to 10b. As shown in Fig, 8, several light sources 11 may be arranged surrounding the inner circumference 5 of the annular disc 3, optionally being fixed to the element also carrying the adaptable reflector 1. The light source(s) 11 may be any suitable kind of light source such as a halogen or Xenon bulb, however, LEDs are preferred.

[0048] As shown in Figs. 1 to 3, 10a, and 10b, the optical illumination system 2 also comprises a base element 12 configured to carry the adaptable reflector 1 and a movable element 13 configured to generate movement of the adaptable reflector 1 between the first shape SI and the second shape S2 and / or to maintain the adaptable reflector 1 in the first shape SI and / or the second shape S2.

[0049] The reflector 1 may be fixed to the base element 12 such that a first section 21 of the disc 3 is immobile in directions along an optical axis O of the optical illumination system 2, and a second section 22 of the disc 3 is moveable in directions along the optical axis O. This is illustrated in Figs 2a to 3, 10a, and 10b which show that the first section 21, in these embodiments comprising the inner circumference 5 of the annular disc 3, remains substantially stationary as the disc 3 adopts the second shape S2. Regardless of shape, the first section 21 may remain within the same plane, preferably a plane perpendicular to the optical axis O of the optical illumination system 2. When the disc 3 has adopted the second shape S2, the second section 22 has been offset from the first section 21 in at least directions parallel with the optical axis O. The second section 22 may include the main part of the disc 3 including the outer circumference 6.

[0050] The movable element 13 may comprise a sleeve 14 and a cover 15 configured to engage a surface of the sleeve 14, as shown in Figs 2a to 3, 10a, and 10b. A void 23 formed between the sleeve 14 and the cover 15 is configured to accommodate at least a part of the second section 22 of the disc 3, e.g. the outer circumference 6. This allows movement of the movable element 13 along the optical axis O to generate movement of the second section 22 and, hence, movement of the disc 3 between the first shape SI and the second shape S2.

[0051] The cover 15 may be a front glass cover configured to protect the light source 11, also referred to as the flash 11. The cover 15 may be provided with optical power, e.g. have a lens-shaped profile configured to control the outgoing light beam. It may also be provided with a diffusive surface treatment to make the light pattern softer. As shown in Figs. 2a to 3, 10a, and 10b, the cover or front glass 15 may have a substantially cone-shaped mirror surface at the center of its bottom surface, i.e. the surface facing the reflector 1 and light source 11. This is to direct the light to the reflector 1. The light source(s) 11 may be arranged within the sleeve 14 as shown in the figures, however, the light source(s) 11 may also be positioned at the bottom surface of the front glass 15, pointing downwards to the reflector 1.

[0052] As mentioned, the sleeve 14 can be used to drive the reflector together with the cover 15. As the sleeve 14 moves, e.g. along the optical axis O, the disc 3 can be forced into a cone-like shape as illustrated in Figs 2b, 3, and 10b. This focuses the light beam to a narrow field of view, see the arrows in Fig. 10b. When the sleeve 14 moves in the opposite direction, to the location shown in Figs. 2a and 10a, the sleeve 14 presses the reflector disc 3 flat resulting in wide field of view light beam, see the arrows in Fig. 10a. If the reflector is driven directly by opening and closing the cut or overlap created by discontinuity 4, the movable element 13 follows the linearly moving reflector edge, or outer circumference 6, which maintains the straightness and the shape of the reflector 1.

[0053] The sleeve 14 may be provided with a flat reflective top surface compensating tor the lack of reflection due to discontinuity 4 when the reflector 1 is, e.g. planar. The sleeve 14 may also be provided with a reflective slanted surface configured to reflect light from the light source(s) 11 in embodiments such as that shown in Fig. 9 which is provided with four light sources 11, the reflective slanted surface reflecting light towards the object or towards the reflector 1.

[0054] As shown in Figs. 3, 10a, and 10b, a first thread 16 may be arranged on the base element 12 and be configured to engage a second thread 17 arranged on the moveable element 13. This allows rotating actuation. As shown in Fig. 1, one of the base element 12 and the moveable element 13 may comprise at least one protrusion 18 and the other of the base element 12 and the moveable element 13 may comprise at least one groove 19 configured to receive the protrusions 18, as illustrated in Fig. 1. This allows linear actuation as also illustrated in Figs. 2a and 2b.

[0055] Rotational and linear actuation may be combined by e.g. arranging the grooves 19 in parallel with the optical axis O, rotational movement of one of the base element 12 and the moveable element 13 being transformed to linear movement of the other of the base element 12 and the movable element 13 along the optical axis O, via groove 19 and protrusion 18.

[0056] The present invention also relates to an electronic apparatus 20 comprising the abovedescribed optical illumination system 2.

[0057] The various aspects and implementations have been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject-matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0058] The reference signs used in the claims shall not be construed as limiting the scope. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this disclosure. As used in the description, the terms “horizontal”, “vertical”, “left”, “right”, “up” and “down”, as well as adjectival and adverbial derivatives thereof (e.g., “horizontally”, “rightwardly”, “upwardly”, etc.), simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader. Similarly, the terms “inwardly” and “outwardly” generally refer to the orientation of a surface relative to its axis of elongation, or axis of rotation, as appropriate.

Claims

CLAIMS1. An adaptable reflector (1) for an optical illumination system (2), said reflector (1) comprising a disc (3), a discontinuity (4) extending from an edge of said disc (3) towards an interior of said disc (3), said discontinuity (4) allowing said disc (3) to adopt a first shape (SI) and a second shape (S2), said disc (3) being configured to reflect light rays towards a first image area (Al) when in said first shape (SI) and to reflect light rays towards a second image area (A2) when in said second shape, said first image area (Al) being larger than said second image area (A2).

2. The adaptable reflector (1) according to claim 1, wherein said disc (3) is annular, and said discontinuity (4) extends radially from an inner circumference (5) of said annular disc (3) to an outer circumference (6) of said annular disc (3).

3. The adaptable reflector (1) according to claim 1 or 2, wherein said discontinuity (4) forms a gap in said disc (3), said gap being delimited by a first disc edge (7) and a second disc edge (8).

4. The adaptable reflector (1) according to any one of the previous claims, wherein said discontinuity (4) is formed by a throughgoing slit or by a section of said disc (3) being removed.

5. The adaptable reflector (1) according to claim 3 or 4, wherein said first disc edge (7) and said second disc edge (8) extend adjacent each other when said disc (3) has adopted said second shape (S2).

6. The adaptable reflector (1) according to claim 3 or 4, wherein said first disc edge (7) and said second disc edge (8) overlap a surface (9) of said disc (3) when said disc (3) has adopted said second shape (S2).

7. The adaptable reflector (1) according to any one of the previous claims, wherein said discontinuity (4) comprises resilient material.

8. The adaptable reflector (1) according to any one of the previous claims, further comprising a resilient element (10) attached to a surface (9) of said disc (3) on opposite sides of saiddiscontinuity (4), said resilient element (10) being configured to move said disc (3) between said first shape (SI) and said second shape (S2) and / or to maintain said disc (3) in said first shape (SI) and / or said second shape (S2).

9. The adaptable reflector (1) according to any one of the previous claims, wherein said first shape (SI) is planar and said second shape (S2) is non-planar.

10. The adaptable reflector (1) according to any one of the previous claims, wherein at least one surface (9) of said disc (3) comprises a reflective coating and / or a surface profile.

11. An optical illumination system (2) comprising the adaptable reflector (1) according to any one of claims 1 to 10, at least one light source (11), a base element (12) configured to carry said adaptable reflector (1), and a movable element (13) configured to generate movement of said adaptable reflector (1) between the first shape (SI) and the second shape (S2) and / or to maintain said adaptable reflector (1) in said first shape (SI) and / or said second shape (S2).

12. The optical illumination system (2) according to claim 11, wherein the reflector (1) is fixed to said base element (12) such that a first section (21) of said disc (3) is immobile in directions along an optical axis (O) of said optical illumination system (2), and a second section (22) of said disc (3) is moveable in directions along said optical axis (O).

13. The optical illumination system (2) according to claim 11 or 12, wherein said movable element (13) comprises a sleeve (14) and a cover (15) configured to engage a surface of said sleeve (14), a void (23) between said sleeve (14) and said cover (15) accommodates at least a part of said second section (22) of said disc (3) such that movement of said movable element (13) along said optical axis (O) generates movement of said second section (22) and movement of said disc (3) between said first shape (SI) and said second shape (S2).

14. The optical illumination system (2) according to claim 13, wherein a first thread (16) arranged on said base element (12) is configured to engage a second thread (17) arranged on said moveable element (13), andwherein one of said base element (12) and said moveable element (13) comprises at least one protrusion (18) and the other of said base element (12) and said moveable element (13) comprises at least one groove (19) configured to receive said protrusion(s) (18), said groove(s) (19) extending in parallel with said optical axis (O) such that rotational movement of one of said base element (12) and said moveable element (13) is transformed to linear movement of the other of said base element (12) and said movable element (13) along said optical axis (O).

15. An electronic apparatus (20) comprising the optical illumination system (2) according to any one of claims 11 to 14.

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