The present invention relates to an optical device comprising a lens having an adjustable focal length.
Regarding such optical devices it is desirable to provide focus adjustable lenses that have a small installation space.
This problem is solved by an optical device having the features of claim 1.
Preferred embodiments of the present invention are stated in the respective sub claims and are described below.
According to claim 1 the optical zoom device comprises: a lens having an adjustable focal length, the lens comprising a container that encloses a lens volume and a reservoir volume that is connected to the lens volume, wherein the two volumes are filled with a transparent liquid, wherein the container further comprises a flat lateral wall structure having a front side and a back side (wherein particularly the front side faces away from the back side), an elastically deformable and transparent membrane, a transparent cover element, and an elastically deformable wall portion, wherein the membrane is connected to the back side of the lateral wall structure, and wherein the cover element is connected to the front side of the lateral wall structure such that the lens volume is arranged between the cover element and the membrane, and wherein the wall portion is arranged adjacent the reservoir volume, and wherein the wall portion comprises an inside and an outside facing away from said inside, wherein the inside contacts the liquid residing in the reservoir volume, and wherein the lens further comprises a lens shaper that is connected to the membrane and defines an area of the membrane, which area has an adjustable curvature and contacts the liquid in the lens volume, and wherein the lens further comprises a movable piston connected to the outside of the wall portion and configured to act on said outside to pump liquid from the reservoir volume into the lens volume or from the lens volume into the reservoir volume so as to change the curvature of said area of the membrane and therewith the focal length of the lens.
Particularly, the notion flat regarding the lateral wall structure means that the lateral wall structure comprises a thickness in a direction normal to the front side or the back side that is smaller than an extension of the lateral wall structure in a direction perpendicular to an optical axis of the lens. Particularly, the membrane and the cover element face each other in the direction of the optical axis of the lens. Particularly, the cover element and/or the membrane extend perpendicular to the optical axis.
Furthermore, particularly, the lens shaper is preferably fixed with respect to the container, i.e. it does not move with respect to the cover element or the lateral wall structure.
Particularly, the present invention allows providing a thin liquid lens that can include an actuator which can be based on a magnet and an electrical coil.
The approach according to the present invention is easily scalable to different clear apertures and allows minimizing the outer dimensions of the device in three directions (e.g. all directions not pointing in the actuator direction).
Particularly, the shape of the lens is advantageously customizable to maximize the possible camera display area of an electronic device (e.g. smart phone), e.g. by using an asymmetric actuator/pump configuration.
Furthermore, the container of the liquid lens can comprise a bent shape, particularly so as to adapt the container of the lens to a component of the optical device (such as a lens barrel) and to allow an arrangement of the container with respect to the component that minimized installation space. Corresponding embodiments will be explained in detail below.
Particularly, the present invention can be applied to a wide variety of different applications, such as
Particularly, the piston is movable to push against the outside of the wall portion to pump liquid from the reservoir volume into the lens volume or to pull on the outside to pump liquid from the lens volume into the reservoir volume. Due to the incompressibility of the liquid, pumping of liquid into the lens volume will increase a curvature of said area of the lens (starting with a flat area) and therewith the focal power while removing liquid from the lens volume into the reservoir volume will again decrease the curvature of said area. Thus, by pumping liquid between the two volumes, the curvature of said area of the membrane can be adjusted (e.g. from concave to convex or from flat to convex) so that the container forms a lens having an adjustable curvature. Thus, light passing through the container (e.g. through the cover element, the liquid in the lens volume and the membrane, is refracted according to the focal length defined by the curvature of said area of the membrane.
Particularly, according to an embodiment of the invention, the lateral wall structure comprises a plate member comprising a through-opening for accommodating at least a portion of the lens volume and an adjacent recess for accommodating at least a portion of the reservoir volume. Particularly this recess of the plate member can also be a (further) through-opening of the plate member.
Further, according to an embodiment of the invention, the lens shaper comprises a through-opening delimited by a circular edge that contacts the membrane to define said area of the membrane.
According to an embodiment of the invention, the membrane is arranged between the plate member and the lens shaper. Here, particularly, the lens shaper can be formed by a further plate member, wherein the lens shaper (further plate member) comprises said through-opening delimited by said circular edge, as well as a further through-opening configured to expose said wall portion on which the piston acts. Alternatively, the lens shaper can be formed by a ring member.
Further, according to an alternative embodiment of the invention, the membrane is connected to the plate member via the lens shaper, so that the lens shaper is arranged between the membrane and the plate member. Here, particularly, the lens shaper can be formed by further plate member, wherein the through-opening of the lens shaper that is delimited by said circular edge of the lens shaper accommodates a portion of the lens volume, and wherein the lens shaper (further plate member) comprises a further through-opening for accommodating a portion of the reservoir volume.
According to a further alternative embodiment, the lens shaper is formed by the plate member itself, wherein the circular edge of the lens shaper is formed by a circular edge of said through-opening of the plate member.
Furthermore, according to an embodiment of the present invention, the plate member is a printed circuit board, wherein said circular edge is formed by an etched metal layer (e.g. metal formed by or comprising copper) of the printed circuit board.
Alternatively, the lateral wall structure of the plate member or the further plate member can be formed out of or can comprise: a metal, a plastic material, a polymer. Particularly, the lateral wall structure or the plate member or the further plate member can be an injection molded part.
Further, according to an embodiment of the invention, the cover element is connected to the plate member so that the cover element covers the through-opening of the plate member and/or the recess of the plate member.
According to a further embodiment, a further membrane is arranged between the plate member and the cover element. The further membrane can cover the through-opening and/or the recess of plate member. Particularly, the further membrane can be adapted to improve index matching between the liquid and cover element of the lens.
Furthermore, according to an embodiment, the cover element can be formed out of or can comprise one of the following materials: a glass, a plastic material, a polymer.
Further, according to an embodiment of the invention, the reservoir volume is arranged opposite the lens volume in a direction perpendicular to the optical axis of the lens. Thus, particularly, the arrangement of the reservoir volume with regard to the lens volume is asymmetric with respect to the optical axis. Particularly, this allows one to place the lens volume portion of the container that particularly comprises a comparatively small height in the direction of the optical axis on top of a lens barrel (which adds only a small height to the installation height of the lens barrel), while the bulkier part (e.g. the reservoir volume portion of the container including the piston connected to the outside of said wall portion on which the piston acts) can be arranged laterally with respect to the lens barrel.
According to a preferred embodiment, said wall portion to which the piston is connected, is formed by a portion of the membrane of the lens, which in this case preferably covers the whole back side of the lateral wall structure or plate member.
Furthermore, according to yet another embodiment, the container comprises a first portion surrounding the lens volume and a second portion surrounding the reservoir volume, wherein the first portion encloses an obtuse angle with the second portion (i.e. said angle is larger than 90° and smaller than 180°. Also here, the reservoir portion of the container, due to extending at an angle with respect to the lens volume portion of the container, can be arranged laterally with respect to the lens barrel, when the container is arranged on a face side of the lens barrel.
Furthermore, according to an embodiment of the present invention, the optical device comprises a lens barrel, wherein the lens barrel extends around an internal space of the lens barrel, wherein the lens barrel further comprises a plurality of rigid lenses arranged on top of one another in said internal space, and wherein the lens barrel comprises a face side that delimits an opening via which light can enter the internal space of the lens barrel to pass through the rigid lenses, and wherein the face side is connected to a lateral outer surface of the lens barrel, which lateral outer surface extends around the internal space.
Furthermore, the optical device can comprise an optical image sensor that can be arranged in the internal space of the lens barrel or in front of the lens barrel such that the rigid lenses face the image sensor and light entering said opening of the lens barrel along an optical axis of the lens barrel (i.e. of the rigid lenses therein) can pass through the rigid lenses to impinge on the optical image sensor.
Further, according to an embodiment of the invention, the lens further comprises a housing connected to the container of the lens such that the housing encloses the piston together with the container.
Particularly, according to an embodiment, the container and/or the housing are connected to the lens barrel, such that the container is arranged on the face side of the lens barrel and the lens volume faces the rigid lenses of the lens barrel, and such that the piston faces the lateral surface of the lens barrel in a direction perpendicular to the optical axis of the lens (or of the lens barrel). Further, particularly, the housing of the piston is arranged on the lateral surface of the lens barrel.
Furthermore, according to an embodiment, the container and/or the housing are glued to the lens barrel.
Further, according to an embodiment of the present invention, the container and/or the housing are arranged (or connected) to the lens barrel in a form fitting manner.
Furthermore, in an embodiment, the container forms a stop of the piston in a first movement direction of the piston in which the piston pushes against the outside of the wall portion. Furthermore, particularly, enclosing the piston with the housing allows to provide a stop for the piston in a second movement direction of the piston in which the piston pulls at the outside of the wall portion. According to a further embodiment, the housing can also form a stop for the piston in a direction perpendicular to said movement directions. Thus, the housing and/or the container of the lens help to limit a movement of the magnet (e.g. due to a mechanical shock) which improves protection of the membrane/wall portion to which the magnet is connected and which supports the magnet.
Further, according to an alternative embodiment of the present invention, instead of providing a separate housing for the piston, the face side of the lens barrel can comprises a recess for receiving the piston, wherein the container is now connected (particularly glued) to the face side of the lens barrel such that the lens volume faces the rigid lenses of the lens barrel and such that the piston protrudes from the outside of the wall portion into the recess of the face side of the lens barrel. Here, the lens barrel itself provide a housing for the piston.
Also here, particularly, the bottom of the recess or a printed circuit board arranged thereon can form a stop for the piston in the second movement direction of the piston in which the piston pulls at the outside of the wall portion. Further, an inner side of the recess can form a stop for the piston in a direction perpendicular to the first and second movement direction of the piston. Furthermore, also here, the container can form a stop for the piston in the first movement direction of the piston in which the piston pushes against the outside of the wall portion.
Further, according to an embodiment of the invention, the housing of the piston (or the recess of the lens barrel) comprises an air duct connecting an internal space of the housing (or of the recess) in which the piston is arranged to an outside of the housing (or of the lens barrel) to allow venting of the internal space (or recess of the lens barrel).
Further, according to an embodiment of the invention, the housing (or recess of the lens barrel) comprises a further air duct connecting the internal space of the housing (or of the recess) with the internal space of the lens barrel to allow venting of the internal space of the lens barrel. Alternatively (or in addition) the optical device can comprises a further air duct connecting the internal space of the lens barrel to an outside of the lens barrel.
Instead of providing an installation space saving connection of the lens to a lens barrel, the lens can also be connected in an advantageous manner to other optical components such as a folding prism. Here, the container of the lens can be connected (particularly glued) to a surface of the folding prism. Particularly, the container is connected such to said surface the folding prism that the membrane of the lens is arranged between said surface of the folding prism and the cover element of the lens. Also here, the optical device can comprise a lens barrel as described above, wherein the lens barrel is now preferably arranged in an optical path of the optical device between the folding prism and an optical image sensor of the optical device. Particularly, the lens barrel can be configured to move with respect to the image sensor so as to provide autofocus and/or optical image stabilization. However, also in such a configuration, the lens can perform an autofocus function, and is particularly also capable to generate macro shots.
Further, according to an embodiment of the invention, the optical device comprises an actuator, wherein the actuator is configured to move the piston such that the piston pushes against the outside of the wall portion to pump liquid from the reservoir volume into the lens volume so as to change the curvature of said area of the membrane (e.g. from flat to convex) and therewith the focal length of the lens, and/or wherein the actuator is configured to move the piston such that the piston pulls at the outside of the wall portion to pump liquid from the lens volume into the reservoir volume so as to change the curvature of said area of the membrane (e.g. from convex to less convex or flat) and therewith the focal length of the lens.
Further, according to an embodiment of the invention, the piston comprises a magnet, wherein the magnet particularly forms a component of the actuator.
Further, according to an embodiment of the invention, the magnet is connected to the outside of the wall portion via a spacer.
Further, according to an embodiment of the invention, the actuator comprises an electrically conducting coil configured to interact with the magnet to move the piston when an electrical current flows through the coil, wherein particularly the movement direction of the piston, e.g. towards the outside of the wall portion to push against the outside of the wall portion (first movement direction) or away from the outside to pull at the outside of the wall portion (second movement direction), depends on the direction of the current flowing through the coil (for a given orientation of the magnetization of the magnet). Particularly, the optical device can comprise a driver circuit to control said electrical current.
Further, according to an embodiment of the invention, the coil comprises an electrical conductor which comprises windings that extend around an (e.g. virtual) winding axis, wherein particularly, the winding axis extends parallel to the optical axis of the lens and/or normal to the wall portion of the container.
Particularly, according to an embodiment, the coil faces the magnet in the direction of the winding axis, wherein the magnetization of the magnet extends parallel to the winding axis. Alternatively, the magnet can also be arranged such that the magnet is at least partially arranged in a space (e.g. air gap) surrounded by the windings of the coil. Also here, the magnet can comprise a magnetization that extends parallel to the winding axis. Furthermore, alternatively, in case the magnet is at least partially arranged in said space or is completely arranged in said space that is surrounded by the windings of the coil, the magnet can be a ring magnet that is radially polarized, i.e. comprises a magnetization extending in a radial direction of the ring magnet. Here, particularly, the magnetization extends perpendicular to the winding axis.
Further, according to an embodiment of the invention, the coil is integrated into the plate member and particularly extends along a boundary of the recess of the plate member that accommodates the reservoir volume, wherein particularly the magnet faces the coil in the first movement direction, and wherein particularly the magnet comprises a magnetization that extends parallel to the winding axis of the coil.
Further, according to an embodiment, the magnetization can extend parallel to the first or second movement direction of the piston and/or parallel to the optical axis of the lens.
Further, according to an embodiment of the invention, the coil is one of: integrated into a printed circuit board that is arranged on a bottom of the recess of the face side of the lens barrel (see above), arranged on a bottom of the recess of the face side of the lens barrel, integrated into a bottom of the recess of the face side of the lens barrel. Particularly, the magnet can face the coil in the second movement direction of the piston. Furthermore, particularly, the magnet can comprise a magnetization that extends parallel to the winding axis. Further, particularly, the printed circuit board comprising the coil can be connected via a flexible conductor to a further (e.g. flexible) connector configured to provide electrical contact to the optical device, particularly to provide electrical contact to the image sensor and to the lens (e.g. to the actuator of the lens).
Further, according to an embodiment of the invention, the lens barrel comprises an electrical connector molded into the lens barrel, wherein the electrical connector protrudes out of the lens barrel with two first end sections that are soldered to the coil, and wherein particularly the electrical connector protrudes out of the lens barrel with two second end sections that form solderable electrical contacts.
Further, according to an embodiment of the invention, the housing of the piston comprises a bottom facing the wall portion, and a lateral wall connecting the bottom of the housing to the container of the lens.
Further, according to an embodiment of the invention, the coil is integrated into the bottom of the housing or arranged on the bottom of the housing, such that the magnet faces the coil in the second movement direction of the piston. Here, the magnet can comprise a magnetization that extends parallel to the winding axis of the coil.
Further, according to an embodiment of the invention, the coil is integrated into the lateral wall of the housing or is arranged on the lateral wall of the housing, wherein particularly the magnet is at least partially or completely arranged in a space (e.g. air gap) surrounded by the windings of the coil. Here, particularly, the magnet can comprise a magnetization that extends parallel to the winding axis (axially polarized) or perpendicular to the winding axis (radially polarized).
Further, according to an embodiment of the invention, the actuator comprises a member formed out of a shape memory alloy for moving the piston, which member particularly connects the piston to said housing of the piston or to the lens barrel, wherein particularly said member comprise a state in which the member causes the piston to pull at the outside of the wall portion. The actuator may also comprise a plurality of shape memory alloy members to allow a push/pull operation regarding the piston structure.
In the following, further features as well as embodiments of the present invention are described with reference to the Figures that are appended to the claims, wherein:
The present invention relates to an optical device 1, e.g. a camera, as shown e.g. in
Further, said wall portion 22 is arranged adjacent the reservoir volume R, wherein the wall portion R comprises an inside 22a and an outside 22b facing away from said inside 22a, wherein the inside 22a contacts the liquid L residing in the reservoir volume R (cf. e.g.
To assure that the membrane 20 develops a defined, precise curvature, the lens 10 further comprises a lens shaper 40 that is connected to the membrane 20 and defines an e.g. circular area 21 of the membrane 20, which area 21 has an adjustable curvature and contacts the liquid L in the lens volume V. For adjusting this curvature and therewith the focal length of the lens 10, the lens 10 further comprises a movable piston 50 connected to the outside 22b of the wall portion 22 and configured to act on said outside 22b to pump liquid L from the reservoir volume R into the lens volume V or vice versa. Preferably, the wall portion 22 is formed by a portion of the membrane 20. Particularly, the piston 50 can be enclosed by a housing 80 connected to the container 11 of the lens 10 (cf. e.g.
Adjustment of the focal length of the lens 10 is exemplary illustrated e.g. in
As indicated in
The lens barrel 60 deflects light that passes the lens barrel 60 along an optical axis A′ of the lens barrel 60 onto an image sensor 70 of the optical device (e.g. camera), wherein the lens 10 (e.g. adjustment of the focal length) can be driven by an optical autofocus feedback signal provided by the image sensor 70.
Particularly, as indicated in
Generally, the container 10 can comprise a relatively small height in the direction of the optical axis A of the lens L while the portion comprising the reservoir volume R and piston 50 connected to the membrane portion 22 demands a larger installation space in said height direction (along the optical axis A).
However, the design of the container 11 of the lens 10 allows an asymmetrical arrangement of the container 11/reservoir volume R with regard to the optical axis A, so that only a small height that can be smaller than 0.5 mm is added to the lens barrel 60. Particularly, the asymmetric arrangement of the container 11 allows to move the lens to an edge of a display of a mobile phone.
Particularly, as shown in
Apart from an arrangement of the lens 10 on a lens barrel, the asymmetric arrangement can also be used in conjunction with other optical components such as a folding prism 3 which is shown in
Also here, the optical device 1 can comprise a lens barrel 60 (see above), wherein the lens barrel 60 is now preferably arranged in an optical path P of the optical device 1 between the folding prism 3 and an optical image sensor 70 of the optical device 1. Particularly, the lens barrel 60 can be configured to move with respect to the image sensor 70 so as to provide autofocus and/or optical image stabilization. However, also the lens 10 can provide autofocus and macro.
Here, a recess 66 is formed in the face side 63 of the lens barrel 60 for receiving the piston 50, wherein the container 11 of the lens 10 is connected, particularly glued, to the face side 63 of the lens barrel 60 such that the lens volume V faces the rigid lenses 62 of the lens barrel 60 and such that the piston 50 protrudes from the outside 22b of the wall portion 22 into the recess 66. Thus, in this embodiment, a housing for enclosing the piston 50 is formed by the lens barrel 60.
Particularly, to achieve such a configuration, an outer shape of the lens barrel 60 is adapted to accommodate space for the actuator, particularly to provide a cavity for the piston 50. Furthermore, a coil 101 for moving the piston 50 can be integrated into a printed circuit board (PCB) 103 that is arranged on a bottom 66a of the recess 66 wherein the coil 101 can be connected via a flexible conductor 104 to a further flexible connector 105 at the bottom of the lens barrel 60 that serves for electrically contacting the optical device 1.
Particularly, the configuration shown in
In the following,
Particularly, according to the embodiment shown in
To define said curvature adjustable area 21 of the membrane 20, a lens shaper 40 is provided that is formed by a further plate member 40 (e.g. formed out of a metal, a glass, or a plastic), wherein the membrane 20 is arranged between the plate member 120 and the lens shaper 40. Particularly, the lens shaper 40 comprises a through-opening 41 delimited by a circular edge 42 that contacts the membrane 20 to define said area 21. In order to expose the wall portion 22 of the reservoir volume R, so that the piston 50 can interact with the reservoir volume R, the lens shaper 40 comprises a further through-opening 43. Here, the lens shaper 40 also functions as a distance holder to the lens barrel 60. Furthermore, the lens shaper 40 provides protection to the area 21 when it is in a convex state.
Furthermore,
As shown in
For this, the container 11 comprises a first portion 11a comprising the lens volume V and a second portion 11b comprising the reservoir volume R, wherein the first portion 11a extends at an obtuse angle W with respect to the second portion 11b of the container 11 (cf.
Furthermore, as already mentioned above, in all lens designs a further membrane 25 can be arranged underneath the cover element (e.g. glass) to improve the index matching between liquid L and cover element 30
Furthermore, all plate members 120 discussed above can also be formed by stacking multiple flat elements on top of one another (e.g. instead of depth etching and/or injection molding of the plate member 120).
Furthermore, as indicated in
Furthermore,
Etching of such a top (e.g. copper) layer results in a good quality lens shaper 40. The through-hole 121 of the plate member 120 can be drilled with a precise diameter, but does not need to be optical quality. This allows to build a very small, low cost and thin lens 10.
Alternatively, the lateral wall structure 12 or the plate member 120 or the further plate member 40 described herein can be formed out of or comprise: a metal, a plastic material, a polymer. Particularly, the lateral wall structure 12 or plate member 120 or further plate member 120 can be injection molded. Generally, the cover element 30 can be formed out of or can comprise: a glass, a plastic material, a polymer.
Furthermore,
As shown e.g. in
Particularly, as shown in
Furthermore, as indicated in
Particularly, the respective the coil 101 comprises an electrical conductor 102 which comprises windings 102a that extend around a winding axis C, wherein particularly the winding axis C extends parallel to the optical axis A of the lens and/or normal to the wall portion 22 of the container 11.
To achieve a very thin design, the coil 101 can be integrated into the plate member (PCB) 120, as shown in
Furthermore, as described in conjunction with
Furthermore, in the embodiments shown in
Particularly, according to the embodiment shown in
As further indicated in
As illustrated in
In this regard
Furthermore, in general, the lens 10 (particularly to the coil 101 of the actuator 100 of the lens) can be electrically contacted by using a pin header, a flex cable (e.g. w/o dedicated connector) or half vias, particularly to directly connect the lens 10 to a camera module. According to a preferred variant shown in
In other words, the lens barrel 60 can comprises an electrical connector 106 molded into the lens barrel 60 (e.g. by way of insert molding), wherein the electrical connector 106 protrudes out of the lens barrel 60 with two first end sections 106a that are soldered (or otherwise electrically connected) to the coil 101, and wherein particularly the electrical connector 106 protrudes out of the lens barrel 60 on an opposite side with two second end sections 106b that are e.g. soldered to electrical contacts arranged on a printed circuit board or a flexible connector 105.
Finally,
Furthermore, all actuators described herein that are based on an electrical coil can comprise a coil that can be wound coil or a PCB coil (e.g. a coil integrated into a PCB). Particularly in case of PCB coils, a driver can be directly soldered onto the PCB of the coil 101 and controlled using a digital signal, e.g. I2C, SPI etc.
Number | Date | Country | Kind |
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18168346.7 | Apr 2018 | EP | regional |
18193557.8 | Sep 2018 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2019/060384 | 4/23/2019 | WO | 00 |