Patent Description:
A lens device of the afore-mentioned kind usually comprises a transparent and elastically expandable membrane, an optical element opposing or facing the membrane, a wall member, wherein the optical element and the membrane are connected to the wall member such that a volume is formed, wherein at least the membrane, the optical element, and said wall member delimit said volume (also denoted as container), a fluid residing in said volume, and a lens shaping member attached to an outside of the membrane, which outside faces away from said volume. Tunable lens devices, especially for image stabilization are known in the state of the art. <CIT> describes an imaging device where a liquid lens comprises a liquid-liquid interface between first and second immiscible liquids deformable by electro-wetting.

Further, <CIT> discloses an image stabilization device and method, wherein actuators act on both sides of a flexible lens, so as to tilt one side and to bend the other side.

Furthermore, <CIT> describes an electro-active lens comprising an optical element being an elastic solid, wherein upon application of a voltage to electrodes of the optical element, the latter is deformed in order to alter its optical properties.

Furthermore, <CIT> discloses a variable focus lens comprising an electrically conductive elastic plate and electrodes arranged on both the sides of the electrically conductive elastic plate.

Based on the above, the problem underlying the present invention is to provide for a lens device that allows for tuning the focus of the lens device as well for adjustments of the light beam direction (e.g. for the purpose of image stabilization or beam redirecting) in a simple manner.

This problem is solved by a lens device having the features of claim <NUM>.

Preferred embodiments of the lens device are stated in the corresponding sub claims and are described below.

According to claim <NUM>, the lens device comprises an actuator means that is designed to move the optical element in an axial direction with respect to the lens shaping member (e.g. towards and away from the lens shaping member), so as to adjust the pressure of the fluid residing inside the volume and therewith a curvature of said membrane, wherein said axial direction is oriented perpendicular to a plane spanned by the lens shaping member, and wherein said actuator means is designed to tilt the optical element with respect to said plane, so as to form the volume into a prism for deflecting light travelling through the volume, and wherein the actuator means is designed to act on the wall member for moving the optical element axially and for tilting the optical element.

The fluid resides in the volume such that the curvature of the membrane can be adjusted by adjusting the pressure (or force) exerted on the membrane (e.g. via the lens shaping member). The fluid fills the volume completely.

Further, particularly, the notion, that the lens shaping member spans a plane means that the lens shaping member spans or defines a fictitious plane or extends along such a fictitious (extension) plane. This plane being particularly a fictitious plane may be used for defining directions, such as an axial direction running perpendicular to said plane. Particularly, one may also state that said axial direction runs perpendicular to the lens shaper. In embodiments, where the lens shaper is a circumferential structure said structure or a surface thereof extends in said plane (and thus defines or spans said plane).

Particularly, when the optical element is moved along the axial direction the lens shaping member presses against the membrane or pulls the membrane accordingly.

When the lens shaping member presses against the membrane due to the movement of the optical element/wall member towards the fixed lens shaping member, the pressure of the fluid increases due to the essentially constant volume of the fluid causing the membrane to expand and said curvature of the membrane to increase. Likewise when the lens shaping member pushes less against the membrane or even pulls the membrane, the pressure of the fluid decreases causing the membrane to contract and said curvature of the membrane to decrease. Increasing curvature thereby means that the membrane may develop a more pronounced convex bulge, or that the membrane changes from a concave or a flat state to a convex one. Likewise, a decreasing curvature means that the membrane changes from a pronounced convex state to a less pronounced convex state or even to a flat or concave state, or changes from a flat or concave state to an even more pronounced concave state.

Thus, in other words, the present invention enables autofocus and image stabilization by deforming a membrane by moving only one component axially, here the optical element (or an element such as the wall member connected thereto), with respect to the lens shaping member, and by tilting said component, thus providing a tunable prism.

Hence, advantageously, the invention allows for using the same actuators that are used for deforming the membrane also for x-y scanning (allowing for image stabilization as well as the construction of scanners for beam deflection), while the membrane can still be attached to a fixed lens shaping element. This also allows for preventing lateral displacement of the variable lens surface used for focusing, resulting in better optical quality of the overall optical system.

When tilting, the actuator means is preferably designed to be controlled such that the pressure in the fluid is kept constant, so that the curvature of the membrane is kept constant upon tilting the wall member/optical element.

The membrane can be made of at least one of the following materials: a glass, a polymer, an elastomer, a plastic or any other transparent and stretchable or flexible material. For example, the membrane may be made out of a silicone-based polymer such as poly(dimethylsiloxane) also known as PDMS or a polyester material such as PET or a biaxially-oriented polyethylene terephtalate (e.g. "Mylar").

Further, the membrane can comprise a coating. Further, the membrane can also be structured, e.g. comprise a structured surface.

Further, said fluid preferably is or comprises a liquid metal, a gel, a liquid, a gas, or any transparent, absorbing or reflecting material which can be deformed. For example, the fluid may be a silicone oil (e.g. Bis-Phenylpropyl Dimethicone). Additionally the fluid may include fluorinated polymers such as perfluorinated polyether (PFPE) inert fluid.

Furthermore, the optical element is preferably rigid compared to the membrane. Preferably, the optical element is formed out of or comprises: a glass, a plastic, a polymer, or a metal. It can comprise or can be formed as a (e.g. glass) flat window, a lens, a mirror, a micro structured element with refractive, diffractive and/or reflective structures.

Further, to a preferred embodiment of present invention the optical element may comprise a coating (e.g. anti-reflection).

According to a preferred embodiment of the present invention, the actuator means is designed to move the optical element axially and to tilt it at the same time. Preferably such that the axial movement and the tilt movement can be defined as control variables.

The actuator means is designed to act on the wall member for moving the optical element axially and for tilting the optical element. Further, in the sense described above, the actuator means may be designed to generate a relative movement between the optical element and the lens shaping member, where the optical element and the lens shaping member are moved relative to one another along the axial direction or are tilted with respect to one another.

According to a preferred embodiment of the present invention, the wall member is formed by an e.g. rectangular plate having a continuous recess (e.g. in the center of the plate, which recess extends from a first side of the wall member to a second side of the wall member, which second side faces away from the first side, wherein preferably the optical element is connected to the first side so as to cover said recess, and wherein preferably said membrane is connected to the second side of the wall member.

According to a preferred embodiment of the present invention, the lens shaping member is connected to the wall member, preferably to the second side of the wall member via a deformable wall. According to another preferred embodiment of the present invention, the lens shaping element may be connected to the optical element via a deformable wall. Preferably, the deformable wall then extends through the recess of the wall member/plate to the optical element and therefore delimits said volume (instead of the inner side of the recess).

According to a preferred embodiment of the present invention, said deformable wall is formed as a bellows.

Preferably, said bellows comprises a plurality of regions, wherein preferably each two neighboring regions are connected to each other via a crease, so that said neighboring regions can be folded towards and away from each other about the respective crease, particularly such that when the optical element is moved/tilted towards the lens shaping member said neighboring regions are folded towards each other (at least in a region where the optical element and the lens shaping member approach each other), and such that when the optical element is moved/tilted away from the lens shaping member said neighboring regions are folded away from each other (at least in a region where the optical element and the lens shaping member depart from each other).

The creases of the bellows may be structurally reinforced by rigid elongated members.

In a preferred embodiment of the present invention, the bellows comprises two circumferential regions connected via a single circumferential crease of the bellows.

According to a preferred embodiment of the present invention, the lens shaping member delimits an optically active and elastically expandable (e.g. circular) region of the membrane, wherein particularly said region extends up to an (e.g. circumferential) inner edge of the lens shaping member, and wherein particularly said region comprises said curvature of the membrane to be adjusted.

According to a preferred embodiment of the present invention, the lens shaping member is rigidly connected to a carrier, wherein particularly the carrier faces the second side of the wall member. Said carrier may comprise or may be formed by an optical assembly. The optical assembly may be formed or may comprise an image sensor and/or a lens stack, wherein particularly said lens stack is arranged between the image sensor (e.g. CCD sensor) and the membrane.

According to a preferred embodiment of the present invention, the actuator means comprises a plurality of electrically conducting coils, particularly at least three coils, or four coils, which are arranged on or integrated into the wall member, particularly along the recess. Preferably, each coil is equally spaced from its two neighboring coils along the recess.

According to a preferred embodiment of the present invention, the actuator means comprises a magnet means connected to the carrier. Preferably, said magnet means comprises a plurality of magnets being connect to the carrier respectively, wherein each magnet is preferably associated to a different coil. Preferably, said magnet means or said magnets are designed to interact with said coils such that when a current is applied to a coil the respective coil is either moved towards the carrier (along said axial direction) or away from the carrier (along said axial direction) depending on the direction of the respective current. The displacement of the wall member/plate is proportional to the current.

According to a preferred embodiment of the present invention, a magnetic flux guiding structure (e.g. out of a magnetically soft material such as e.g. iron) for shaping the magnetic flux generated by the respective magnet is provided for each magnet, wherein each magnetic flux guiding structure comprises an end region that protrudes through an associated aperture of the wall member as well as into or through the coils associated to the respective magnet. Preferably, the magnetic flux guiding structures are connected to the carrier, respectively.

According to a further embodiment the actuator means comprises a plurality, particularly, two, three or four, electrically conducting coils connected to the carrier. Preferably, the coils are each arranged adjacent to an associated magnetic flux return structure (e.g. out of a magnetically soft material such as e.g. steel).

Further, preferably, the actuator means comprises a corresponding plurality of magnetic flux guiding structures arranged in or on the wall member, wherein each magnetic flux guiding structure is associated to a different coil, and faces or opposes the respective coil/magnetic return structure such that a gap is present between the respective return structure/coil and associated magnetic flux guiding structure. However, according to a further embodiment, it is also possible that the actuator means comprises only a single magnetic flux guiding structure facing or opposing the coils (e.g. the wall member may itself form the magnetic flux guiding structure). Further, according to a further embodiment, it is also possible that the actuator means comprises only a single return structure adjacent said coils.

When a current now flows through the coils, the magnetic flux is guided through the respective return structure and the respective flux guiding structure. Since the system wants to reduce the magnetic resistance, the respective magnetic flux guiding structure will be attracted to the associated return structure to reduce the gap between the two magnetically soft structures and to reduce the resistance for the magnetic flux. Thus, the wall member and optical element are moved. Depending on the current in the respective coil this allows one to move the wall member axially along said axial direction and/or to tilt the wall member with respect to the plane spanned by the lens shaping member. Such an actuator means is also denoted as reluctance actuator.

According to a further embodiment, the actuator means may comprise a plurality of first electrodes, particularly, two, three or four, arranged in or on the wall member, as well as a corresponding plurality of second electrodes connected to the carrier, wherein each first electrode is associated to a different second electrode and faces or opposes the respective second electrode so that a gap is present between the respectively associated electrodes. By applying a voltage between the respective first and second electrodes, the optical element can be axially moved and or tilted with respect to said plane.

According to a preferred embodiment of the present invention, the lens device comprises a position sensor means for detecting the spatial position of the optical element or of a component connected to the optical element such as the wall member, e.g. with respect to a reference position such as the position of the lens shaping member. By adjusting the spatial position of the optical element to a defined state, the optical properties of the lens device can be defined. This includes the optical power of the lens formed by the deformable membrane, and the angle of the variable prism.

When using an actuator means in the form of a reluctance actuator, the position sensor means can advantageously be designed to use a high frequency current signal for measuring the spatial position of the wall member/optical element via the coils. In other words, in an embodiment of the invention, the actuator means is used to detect the spatial position of the wall member/optical element, particularly by being designed to directly sense the reluctance of the reluctance actuator associated to the gap between the flux guiding structure(s) <NUM> and the return structure(s) <NUM>.

When the wall member moves closer to a coil due to a movement, the gap between the coil/return structure and the wall member becomes less causing the reluctance of the magnetic field to reduce and thus the coil inductance to increase, which is therefore a measure for the width of said gap and therefore for the spatial position of the wall member/optical element. The biggest advantage of this method is that it shows a linear relationship between the output signal and the displacement (gap width) of the wall member/optical element.

According to the present invention, the optical element is transparent. In this case the lens device may be a part of a camera or may itself form a camera, for instance a camera of a mobile phone.

According to an illustrative example not part of the claimed invention, the optical element is formed as a mirror having a reflecting surface facing e.g. towards said volume. For example, said mirror may be adapted to reflect light that enters the lens trough the membrane, travels through said volume, impinges on the mirror and is then reflected towards the membrane.

In this case the lens device may be a part of a scanner or may itself form a scanner. Further, the optical element may comprise a coating.

According to an illustrative example not part of the claimed invention, when said optical element is formed as a mirror, the wall member is connected via a joint to an elongated pin that is slideably arranged in a bushing, wherein particularly said bushing is connected to a housing of the lens device and/or to said carrier. In this manner the movement/tilting of the optical member/wall member can be safely guided.

According to a preferred embodiment of the present invention, the lens device further comprises a movement sensor means for sensing an e.g. unintended rapid movement of the lens device that is to be counteracted. The movement sensor means may be designed to detect a yaw movement and/or pitch movement, i.e. a rotation about two orthogonal axes, which axes are each orthogonal to the optical axis/axial direction.

According to further preferred embodiment of the present invention, for providing image stabilization, the lens device comprises a control unit interacting with said movement sensor means, which control unit is designed to control the actuator means depending on a movement to be counteracted sensed by the movement sensor means such that the optical element is tilted by the actuator means with respect to the plane spanned by the lens shaping member for changing the direction of the incident light beam passing through the lens device in a way that counteracts said sensed unintended rapid movement. This is possible, since the unintended movement causes a displacement of a certain image point, e.g. on the surface of the image sensor, which can be compensated by tilting the optical element and therefore changing the light path of the incident light through the lens device such that the same object point is ending up on the same image sensor location as before the unwanted movement and tilting of the lens device.

Preferably, the control unit is designed to control the actuator means such that the actuator means alters the actual spatial position of the optical element sensed by the position sensor means such that the actual spatial position approaches a reference spatial position of the optical element in which the optical element (and therefore the direction of the incident light beam) is tilted such with respect to the lens shaping member that the unintended rapid movement is counteracted or compensated (see above). Here, alternatively, the actuator means may alter the actual spatial position of the lens shaping member sensed by the position sensor means (i.e. the optical element rests).

Furthermore, a method for adjusting a lens device is disclosed, wherein particularly the method makes use of a lens device according to the invention.

According thereto, the lens device comprises a transparent and elastically expandable membrane, an optical element facing or opposing the membrane, a wall member, wherein the optical element and the membrane are connected to the wall member such that a volume is formed, a fluid residing in said volume, and a lens shaping member connected to an outside of the membrane, which outside faces away from said volume, and wherein the optical element (or alternatively the lens shaping member) is tilted with respect to a plane spanned by the lens shaping member (or with respect to the optical element in case the lens shaping member is tilted) so as to form the volume into a prism for deflecting light passing through the volume.

This method may be used for cameras as well as scanners etc..

Preferably, the optical element is moved also in an axial direction with respect to the lens shaping member (or vice versa), e.g. towards and away from the lens shaping member) so as to adjust the pressure of the fluid residing inside the volume and therewith a curvature of said membrane (particularly so as to adjust the focus of the lens device automatically), wherein said axial direction is oriented perpendicular to said plane (or, as the case may be, to the optical element).

Preferably, the optical element is moved axially by moving the wall member or plate axially along said axial direction. Preferably, the optical element is tilted by tilting the wall member or plate with respect to said plane.

Furthermore, a method for providing image stabilization is disclosed, wherein particularly the method makes use of a lens device according to the invention.

According thereto, the lens device comprises a transparent and elastically expandable membrane, an optical element facing or opposing the membrane, a wall member, wherein the optical element and the membrane are connected to the wall member such that a volume is formed, a fluid residing in said volume, and a lens shaping member connected to an outside of the membrane, which outside faces away from said volume, wherein an unintended rapid movement of the lens device to be counteracted is sensed (e.g. by a movement sensor means), and wherein an actuator means is controlled (e.g. by a control unit) depending on said sensed movement to be counteracted such that the optical element is tilted by the actuator means with respect to a plane spanned by the lens shaping member (or such that the lens shaper is tilted by the actuator means with respect to a plane along which the optical element extends) for changing the direction of the incident light beam passing through the lens device in a way that counteracts said sensed movement (see also above). When tilting, the actuator means is preferably designed (or controlled) such that the pressure in the fluid is kept constant, so that the curvature of the membrane is kept constant.

According to this method, particularly for providing autofocus of the lens device in parallel, particularly at the same time, the optical element is moved by the actuator means in an axial direction with respect to the lens shaping member (or vice versa), e.g. towards and away from the lens shaping member, so as to adjust the pressure of the fluid residing inside the volume and therewith a curvature of said membrane, wherein said axial direction is oriented perpendicular to said plane spanned by the lens shaping member.

According to yet another preferred embodiment of the present invention the actuator means comprises at least one magnet. The at least one magnet may comprise a first and a second side which faces away from the first side. Particularly, the at least one magnet comprises a circumferential or annular shape, so that the at least one magnet comprises a continuous recess extending from the first side to said second side of the at least one magnet.

Particularly, the at least one magnet (or the plurality of magnets, see below) is magnetized perpendicular to said plane in the axial direction.

Further, the lens device particularly comprises a magnetic flux return structure for guiding magnetic flux towards said magnet. Particularly, said return structure (see also above for possible materials) extends along the at least one magnet.

In this respect, particularly, the return structure comprises a circumferential or annular shape and particularly extends along or faces the first side or the second side of the at least one magnet.

Further, particularly, said actuator means comprises at least one coil associated to said at least one magnet, which at least one coil comprises a conductor that is wound around a coil axis running perpendicular to said plane or to said optical element. Particularly, the coil axis coincides with a cylinder axis of the at least one magnet or runs parallel to said cylinder axis of the at least one magnet. Particularly, also the magnetization of the at least one magnet runs parallel to said coil axis and/or cylinder axis.

Further, according to an embodiment, said coil extends along the at least one magnet and faces the at least one magnet (wherein said at least one coil particularly faces the first side or the second side of the at least one magnet), so that when a current is applied to the coil, a Lorentz force is generated that causes the at least one magnet and the at least one coil to attract each other or to repel each other depending on the direction of the current in the at least one coil, particularly so that the optical element is moved in the axial direction with respect to the lens shaping member (or vice versa: so that the lens shaping member is moved in the axial direction with respect to the optical element, see also above) so as to adjust the pressure of the fluid residing inside the volume and therewith a curvature of said membrane (said axial direction is oriented perpendicular to a plane along which the lens shaping member extends, or along which the optical element extends, see above), and/or so as to tilt the optical element with respect to said plane, e.g. the lens shaping member (or vice versa: so as to tilt the lens shaping member with respect to the optical element, see above), particularly so as to form the volume into a prism for deflecting light passing through the volume.

In the above, said at least one coil can have only one winding direction throughout. In an embodiment, only one such coil may be present. The coil then extends particularly along the associated (e.g. single) magnet following the circumferential or annular course of said magnet and facing one or the other side of the magnet.

Further, in another embodiment, in order to increase magnetic forces and their efficiency, the at least one coil comprises an outer first section surrounding an inner second section of the coil (which second section is connected in an electrically conducting fashion to the first section), wherein the conductor is wound around said coil axis running perpendicular to said plane or said optical element such that each section of the coil extends along the at least one magnet (which in this embodiment may be a single magnet) and faces the at least one magnet, wherein in said first section the conductor has a winding direction that is opposite to the winding direction of the conductor in the second section of the coil, so that when a current is applied to the coil, the current flows in one direction in the first section and in the opposite direction in the second section of the coil, and a Lorentz force is generated that either attracts the coil or magnet towards the lens shaping member or pushes the coil or magnet away from the lens shaping member depending on the direction of the current in said sections of the coil. Particularly this allows for generating said axial movement between the optical element and the lens shaping member described above.

Here, instead of having electrically connected sections of a (single) coil one may also provide two separate coils having opposite winding directions or currents in opposite directions.

According to a further embodiment, particularly, for tilting the lens shaping member with respect to the optical element or vice versa, a plurality of magnets is provided which are then particularly arranged around the axis of the lens device (i.e. around the volume of the lens device or along said circumferential return structure). Then, particularly, to each magnet a different coil of a plurality of coils is preferably associated that faces the respective magnet (e.g. its first or second side).

In case of such a plurality of magnets, the coils do not need to have said first and second section described above. Particularly, each coil has a particularly elongated and/or curved contour, following a (particularly elongated and/or curved) contour of the associated magnet (e.g. contour of the first or second side of the respective magnet) so that in one (e.g. outer) half of the coil (which half particularly extends along the elongated dimension of the coil) the current flows in a first direction along the associated magnet while it flows in the opposite direction in the other (e.g. inner) half of the coil (which other half particularly also extends along the elongated dimension of the coil).

In the above, according to an embodiment, the wall member or at least a part of the wall member may be formed by the at least one magnet. The at least one magnet (or a plurality of magnets) can be surrounded by a holding material. Particularly the wall member may be formed by a single magnet. Particularly, the optical element is then connected to the first side of the at least one magnet (or wall member). Further, particularly, said membrane is then connected to the second side of the at least one magnet (wall member). Further, in this embodiment, the return structure is particularly connected to the first side of the at least one magnet (wall member), and the optical element is particularly connected to the first side of the at least one magnet (wall member) via said return structure.

Further, in this embodiment, the at least one coil or the plurality of coils (e.g. when having a plurality of associated magnets but also when having a single associated magnet) is held by a coil frame, particularly having a circumferential or annular shape. Particularly said coil frame faces the at least one (or single) magnet (for instance the second side of the magnet to which the membrane is attached). Particularly, the lens shaping member is connected, particularly integrally, to the coil frame.

In the above, according to another embodiment, the wall member may be designed to hold the at least one coil (or said plurality of coils), so that particularly the at least one coil surrounds said volume. Further, a position sensor means or feedback sensor, e.g. a Hall sensor, for detecting the spatial position of the at least one (or single) magnet with respect to the at least one (or single) coil or vice versa may be connected to the wall member. Here, particularly, the wall member forms, together with the optical element and the membrane a container (volume) for holding the fluid as well as the at least one coil or the plurality of coils and eventually said sensor. The coil and wall member can be a printed circuit board.

Particularly, in this embodiment, the at least one magnet or the plurality of magnets is connected, particularly integrally, to the lens shaping member.

According to a further embodiment, the lens device comprises a temperature sensor that is measuring the temperature of the lens device. The measured temperature can be used to calibrate the lens and make its optical power response to the control signal less temperature sensitive.

Further, according to an embodiment of the present invention, a field guiding plate is placed such that an attractive force builds up between the at least one (or single) magnet and the field guiding plate, such that the force increases when said magnet is moved towards the field guiding plate when the lens (e.g. membrane) becomes more deflected.

Further, in an illustrative example, the lens device may be formed as a so-called double liquid lens. Here, the lens device comprises a further volume on a side facing away from said volume being filled with said fluid, wherein the further volume is filled with a further fluid. The membrane here also delimits one side of said further volume. The advantage of such a configuration is the fact, that the further liquid prevents e.g. a vertically extending membrane from becoming deformed due to gravitation. Embodiments of such lens devices are shown for instance in <FIG>.

Particularly, the lens device according to the invention can be applied in the following: Lighting fixtures, light shows, printers, medical equipment, fiber coupling, head worn glasses, laser processing, biometric, metrology, electronic magnifiers, robot cam, fiber coupling, motion tracking, intra-ocular lenses, mobile phones, military, digital still cameras, web cams, microscopes, telescopes, endoscopes, binoculars, research, industrial applications, surveillance camera, automotive, projectors, ophthalmic lenses, vision systems, range finders, bar code readers.

Further features and advantages of the present inventions as well as embodiments of the present invention shall be described in the following with reference to the Figures, wherein.

<FIG> show schematical cross sectional views of a tunable lens device <NUM> according to the invention. The lens device <NUM> comprises a transparent and elastically expandable membrane <NUM>, a transparent (e.g. planar) optical element <NUM> facing or opposing the membrane <NUM>, a wall member <NUM> in the form of a rectangular plate <NUM> having a continuous circular recess <NUM> formed therein in the center of the plate <NUM>, which recess <NUM> extends from a first side 300a of the plate <NUM> to a second side 300b of the plate <NUM>, which second side 300b faces away from the first side 300a. The rigid optical element <NUM> is connected to the first side 300a, whereas said membrane <NUM> is connected to the second side 300b such that a volume or container V is formed that is at least delimited by the membrane <NUM>, the optical element <NUM>, and said plate <NUM>. The volume V is completely filled with a transparent fluid F. The optical element <NUM>, said volume V with the fluid F residing therein and the membrane <NUM> form a tunable lens. For adjusting the curvature, particularly the focus of this lens, the lens device <NUM> further comprises a lens shaping member <NUM> that is attached to an outside 10a of the membrane <NUM>, which outside 10a faces away from said volume V. The lens shaping member <NUM> thereby delimits an optically active and elastically expandable (e.g. circular) region 10c of the membrane <NUM>, wherein particularly said region 10c extends up to an (e.g. circumferential) inner edge of the lens shaping member <NUM>, and wherein particularly said region 10c comprises said curvature of the membrane <NUM> to be adjusted. The lens shaping member <NUM> may be formed as an annular (e.g. circular) frame for generating a spherical tunable lens, but may also have any other geometry. For instance, a lens shaping member having two parallel opposing linear frame members (i.e. two frame members that face each other) may be used for generating a tunable cylinder lens.

As shown in <FIG>, the lens device <NUM> comprises an actuator means <NUM> that is designed to tilt the optical element <NUM> with respect to a plane spanned by the lens shaping member <NUM> (i.e. the lens shaping member <NUM> defines said fictitious plane or extends in or along said fictitious plane), which allows one to give the volume V under the optical element <NUM> the form of a prism, such that light that passes the volume V is deflected as indicated in <FIG>. This can be employed for image stabilization as well as scanning.

When the lens device <NUM> is used in or as a camera, an image point on the surface of an image sensor <NUM> (cf. <FIG> for instance) may be shifted due to an unintended rapid movement of the lens device <NUM>. This can be counteracted by shifting the crossing point between the incident light beam A' associated to an object point and the surface of the image sensor <NUM> in the opposite direction. For this, the lens device <NUM> may comprise a movement sensor means for sensing said unintended rapid movement of the lens device <NUM> to be counteracted, wherein the lens device <NUM> may further comprise a control unit connected to the movement sensor means, which control unit is designed to control the actuator means <NUM> depending on the movement to be counteracted sensed by the movement sensor means such that the optical element <NUM> is tilted by the actuator means <NUM> with respect to said plane spanned by the lens shaping member <NUM> (i.e. along which plane the lens shaping member extends) for changing the course of the incident light beam A' associated to an object point in a way that counteracts said sensed movement, i.e., the shift of an image point on the surface of an image sensor (or image plane) due to a rapid and unintended movement of the lens device <NUM> is compensated by a shift of the crossing point of said incident light beam A' associated to an object point and the image sensor (image plane) in the opposite direction.

As shown in <FIG> the lens device <NUM> according to the invention is further capable of deforming the membrane <NUM> at the same time by pressing with the lens shaping member <NUM> against the membrane <NUM>. This can be achieved by means of the same actuator means <NUM> that is also designed to move the optical element <NUM> in an axial direction A (being oriented perpendicular to the plane spanned/defined by the lens shaping member <NUM>) with respect to the lens shaping member <NUM> so as to adjust the pressure of the fluid F residing inside the volume V and therewith a curvature of said membrane <NUM> (see also above). This particularly allows one to change the curvature between two different convex curvatures, or two different concave curvatures, or even between a convex and a concave curvature. Thus, the focus of the tunable lens can be altered very effectively. Preferably, the actuator means <NUM> is designed to act on the wall member <NUM> for moving the optical element <NUM> axially as well as for tilting the optical element <NUM> with respect to the fixed lens shaping member <NUM>.

<FIG> also show tilting movements of a lens device <NUM> according to an illustrative example not part of the claimed invention, wherein, in contrast to <FIG>, the lens device <NUM> now comprises an optical element <NUM> in form of a mirror that has a reflecting surface that faces the volume V of the tunable lens. Here, tilting of the optical element <NUM> allows for scanning a 2D image plane.

As shown in <FIG> this can also be combined with deforming the membrane <NUM> for adjusting the focus of the tunable lens as discussed before with respect to <FIG> such that 3D scanning is possible.

<FIG> show a lens device <NUM> of the kind shown in <FIG>, which may form part of a camera, particularly of a camera of a mobile phone. Said device <NUM> comprises in addition a circumferential bellows <NUM> which connects the lens shaping member <NUM> that is attached to the outside 10a of the membrane <NUM> thus defining said region 10c to the second side 300b of the plate <NUM> adjacent to the recess <NUM> of the plate <NUM>. The bellows <NUM> has two circumferential regions <NUM> extending along the lens shaping member <NUM> as shown in <FIG>, which regions <NUM> are connected to each other via a circumferential crease <NUM> extending along said lens shaping member <NUM>. This allows for a contracting and prolonging the bellows <NUM> along the axial direction A and therefore allows for a pronounced tilting movement/axial movement of the plate <NUM>/optical element <NUM>. A contracted bellows <NUM> due to an axial movement of the plate <NUM> towards the lens shaping member <NUM> is shown in <FIG>. As a consequence said region 10c of the membrane <NUM> develops a pronounced convex bulge. A more elongated state of the bellows <NUM> is shown in <FIG> leading to a flat region 10c of the membrane <NUM>. Further, <FIG> shows a tilted plate <NUM>/optical element <NUM> in combination with a convex bulge of the region 10c of the membrane <NUM> due to an axial movement of the plate <NUM>/optical element <NUM> towards the lens shaping member <NUM>.

As indicated in <FIG> the lens shaping member <NUM> is further connected to a carrier <NUM>, which faces the second side 300b of the plate <NUM>. Said carrier <NUM> may comprise or may be formed as an optical assembly such as a lens stack <NUM> and/or an image sensor <NUM> (cf. Thus the lens shaping member <NUM> is fixed and axial movement and tilting of the optical element <NUM> with respect to the lens shaping member <NUM> is accomplished by merely axially moving / tilting the plate <NUM> by means of said actuator means <NUM>.

As can be seen from <FIG>, the actuator means <NUM> comprises four electrically conducting coils <NUM> being integrated into the plate <NUM> along the circular recess <NUM>, wherein each coil <NUM> is equally spaced from its two neighboring coils <NUM> along the circular recess <NUM>.

The actuator means <NUM> further comprises four magnets <NUM>, wherein each magnet <NUM> is associated to one of the coils <NUM>, wherein said magnets <NUM> are connected to the carrier <NUM> and arranged adjacent to the associated coil <NUM>, wherein the respective magnet <NUM> is arranged radially farther outward than the associated coil <NUM>.

Said magnets <NUM> are designed to interact with the respectively associated coils <NUM> such that when a current is applied to a coil <NUM>, the respective coil <NUM> is either moved towards the carrier <NUM> or away from the carrier <NUM> depending on the direction of the respective current.

Further, as shown in <FIG>, for guiding the magnetic flux of the magnets <NUM>, a magnetic flux guiding structure <NUM> is provided for each magnet <NUM>, wherein each magnetic flux guiding structure <NUM> comprises, as shown in <FIG> a first arm <NUM> extending along the axial direction A and an opposing parallel second arm <NUM> (i.e. arm <NUM> faces arm <NUM>) being connected to the first arm via a third arm <NUM> of the structure <NUM>, which third arm <NUM> extends perpendicular to the axial direction A and connects a lower end of the first arm <NUM> to a lower end of the second arm <NUM>. The structure <NUM> further comprises an end region <NUM> of the second arm <NUM>, wherein each of the four end regions <NUM> protrudes through an associated aperture <NUM> formed in the plate <NUM> as well as into or through the respective associated coil <NUM>. The magnets <NUM> are arranged adjacent to the respective first arm <NUM> such that the magnetization of the respective magnet <NUM> points towards the second arm <NUM> and such that the respective magnet <NUM> is arranged between the respective first arm <NUM> and the respective coil <NUM>.

As shown in <FIG>, other magnetic flux guiding structures <NUM> are also possible. <FIG> shows a further structure <NUM> with two opposing magnets <NUM>, <NUM>' (i.e. magnet <NUM> faces magnet <NUM>') which is a modification of the structure <NUM> shown in <FIG>. In <FIG>, the third arm <NUM> further extends towards a fourth arm <NUM> running parallel to the first arm <NUM> and to the second arm <NUM>, wherein the second arm <NUM> now protrudes from the center of the third arm <NUM> and is arranged between the first and the fourth arm <NUM>, <NUM>. The further magnet <NUM>' is arranged adjacent to the fourth arm <NUM> and between the fourth arm <NUM> and the second arm <NUM>, wherein the magnetization of the further magnet <NUM> points towards the second arm <NUM>.

Further, the structure <NUM> shown in <FIG> is a modification of the structure <NUM> shown in <FIG>. In <FIG>, the magnet <NUM> is arranged on the third arm <NUM>, wherein said end region <NUM> that receives the associated coil <NUM> is arranged on top of the magnet <NUM>, wherein the magnetization of the magnet <NUM> now points towards said end region <NUM> of the structure <NUM>.

In order to detect the actual spatial position of the optical element <NUM> / plate <NUM>, the lens device <NUM> comprises a position sensor means <NUM>. This sensor means <NUM> can be formed as a hall sensor <NUM> that is arranged on the plate <NUM>, particularly on the second side 300b of the plate <NUM> and senses an associated signal magnet <NUM> connected to the carrier <NUM>, which signal magnet <NUM> faces or opposes its associated hall sensor <NUM>. Particularly, the respective signal magnet <NUM> is arranged radially outward relative to the associated hall sensor <NUM>.

The lens device <NUM> may comprise for such pairs of hall sensors <NUM> and signal magnets <NUM>, wherein the signal magnets <NUM> are equally spaced along the periphery of the carrier <NUM>. Likewise, the hall sensors <NUM> are equally spaced along the periphery of the plate <NUM>.

Of course, also other position sensor means can be employed such as capacitive sensors, magneto-resistive sensors, or strain sensors.

<FIG> show a further lens device <NUM>, which may form part of camera, particularly of a camera of a mobile phone. The lens device <NUM> is designed as described with respect to <FIG> with the difference that the bellows <NUM> is now omitted. Here, the membrane <NUM> is directly attached to the second side 300b of the plate <NUM> as can be seen from <FIG>, for instance.

As indicated in <FIG>, electrical connections to the coils <NUM> and/or position sensor means <NUM> on the plate <NUM> may be made by means of flexible wires <NUM>, which provides a way for measuring the spatial position of the optical element <NUM>/plate <NUM> by means of strain sensors, wherein such a strain sensor is attached to each flexible wire <NUM>. In case the spatial position of the plate <NUM> is altered by means of the actuator means <NUM> (see above), the flexible wires <NUM> will be deformed which can be detected by means of said strain sensors.

Finally <FIG> and <FIG> show a further lens device <NUM> according to an illustrative example not part of the claimed invention, which is constructed as described with respect to <FIG> with the difference that the optical element <NUM> is now formed as a mirror having a reflecting surface that faces the volume V of the tunable lens. Further, in contrast to <FIG>, the coils <NUM> are arranged on the first side 300a of the plate <NUM>.

The lens device <NUM> shown in <FIG> may form part of a 3D scanner for scanning images. In order to safely guide the movement of the plate <NUM> which has already been described above, the plate <NUM> is connected via a joint <NUM> in the form of a ball bearing to an elongated pin <NUM> that is slidably arranged in a bushing <NUM>. Preferably, the bushing <NUM> is connected to a housing of the lens device <NUM> and/or to said carrier <NUM>. Further electrical connections to the plate <NUM> are preferably made by means of four flexible wires <NUM> which extend from the wall member <NUM>, particularly from the coils <NUM>. The flexible wires <NUM> comprise some slack so that they do not interfere with a movement of the plate <NUM>. Preferably, the flexible wires <NUM> extend from the plate <NUM> towards the bushing <NUM> where they are fastened to the bushing <NUM>.

A further embodiment of an actuator means that can be used to axially move and/or tilt the plate <NUM>/optical element <NUM> of the lens device <NUM> is shown in <FIG>. According thereto the actuator means comprises a plurality, particularly, two, three or four, electrically conducting coils <NUM> rigidly connected to the carrier <NUM>. Preferably, the coils <NUM> are each arranged adjacent to an associated magnetic flux return structure <NUM> (e.g. out of a magnetically soft material such as e.g. steel). The magnetic flux return structure <NUM> may comprise regions <NUM>, <NUM> extending laterally on either side of the respective coil <NUM> as well as a region <NUM> protruding into the respective coil <NUM>. A modification is shown in <FIG> where each magnetic flux return structure <NUM> has a region <NUM> extending laterally, namely radially farther inward than the respective coil <NUM>, as well as a region <NUM> protruding into the respective coil <NUM>. Here, each coil <NUM> has a region protruding beyond the plate <NUM> in the extension plane of the plate <NUM> which respective region of the coil <NUM> is not flanked by a region of the return structure.

The actuator means further comprises a corresponding plurality of magnetic flux guiding structures <NUM> arranged in or on the plate <NUM>, wherein each magnetic flux guiding structure <NUM> is associated to a different coil <NUM>, and faces or opposes the respective coil <NUM>/magnetic return structure <NUM> such that a gap is present between the respective return structure <NUM>/coil <NUM> on one side and the associated magnetic flux guiding structure <NUM> on the other side. The plurality of magnetic flux guiding structures <NUM> can also be made out of one magnetically soft part. The same is true for the return structure <NUM>. there may also be a single magnetic flux guiding structure facing or opposing the coils which are arranged adjacent a single magnetic flux return structure <NUM>.

When a current now flows through the coils <NUM>, the magnetic flux is guided through the respective return structure <NUM> and the respective flux guiding structure <NUM>. Since the system wants to reduce the magnetic resistance, the respective magnetic flux guiding structure <NUM> will be attracted to the associated return structure <NUM> to reduce the gap between the two magnetically soft structures and to reduce the resistance for the magnetic flux. Thus, the plate <NUM> and optical element <NUM> are moved. Depending on the current in the respective coil <NUM> this allows one to move the plate <NUM> axially along said axial direction and/or to tilt the plate <NUM> with respect to the plane spanned/defined by the lens shaping member <NUM>. Such an actuator means is also denoted as reluctance actuator.

This embodiment of an actuator means has the advantage that the coil <NUM> and the Hall sensor <NUM> can be mounted on the carrier <NUM> (cf. for example <FIG>), i.e., at a fixed position with respect to the lens barrel of the fixed optics <NUM> and no flex connection <NUM> is required. Furthermore, less components are required. In this case, the signal magnet <NUM> would be attached to the moveable/tiltable plate <NUM> that comprises or is formed by the flux guiding structures <NUM>. Furthermore, no permanent magnets (except for the Hall sensor) are required. The drawback is that only attractive forces are possible. Furthermore, the Hall sensor can be replaced by directly sensing the variable reluctance of the reluctance actuator, associated to the changing gap between the flux guiding structure <NUM> and the return structure <NUM>.

According to yet another embodiment of an actuator means that can be employed to axially move and/or tilt the plate <NUM>/optical element <NUM> as shown in <FIG>, the actuator means may comprise a plurality of first (top) electrodes <NUM>, particularly, two, three or four, arranged in or on the plate <NUM>, as well as a corresponding plurality of second electrodes <NUM> rigidly connected to the carrier <NUM>, wherein each first electrode <NUM> is associated to a different second electrode <NUM> and faces or opposes the respective second electrode <NUM> so that a gap is present between the respectively associated electrodes <NUM>, <NUM>. By applying a voltage between the respective first and second electrodes <NUM>, <NUM>, the plate <NUM>/ optical element <NUM> can be axially moved and or tilted with respect to said plane spanned/defined by the lens shaping member <NUM>. Thus, besides a magnetic actuation, also an electrostatic actuation is possible. Furthermore, the actuator electrodes <NUM>, <NUM> can be used to sense the distance between the electrodes by reading out the capacitance value between the electrodes.

<FIG> shows a schematical cross sectional view of a further tunable lens device <NUM> according to the invention. As before, the lens device <NUM> comprises a transparent and elastically expandable membrane <NUM>, a transparent (e.g. planar) optical element <NUM> facing or opposing the membrane <NUM>, a wall member <NUM> in the form of an annular magnet <NUM> having a continuous circular recess <NUM> formed therein in the center of the magnet <NUM>, which recess <NUM> extends from a first side 300a of the magnet <NUM> to a second side 300b of the magnet <NUM>, wherein the second side 300b of the magnet faces away from its first side 300a. Furthermore, the magnet <NUM> is axially magnetized (in the axial direction A). The rigid optical element <NUM> is connected to the first side 300a of the magnet <NUM> via a plate-like annular magnetic flux return structure <NUM> that serves for guiding returning magnetic flux back to the magnet <NUM> and that is positioned between the optical element <NUM> and the magnet <NUM>. Said membrane <NUM> is connected to the second side 300b of the magnet such that a volume or container V is formed that is at least delimited by the membrane <NUM>, the optical element <NUM>, said magnet <NUM> forming a circumferential wall member <NUM> of said container, and the return structure <NUM> (which also forms part of the container wall). As described before, the volume V is completely filled with a transparent fluid F. The optical element <NUM>, said volume V with the fluid F residing therein and the membrane <NUM> form a tunable lens. For adjusting the curvature, particularly the focus of this lens, the lens device <NUM> further comprises a lens shaping member <NUM> that is attached to an outside 10a of the membrane <NUM>, which outside 10a faces away from said volume V. The lens shaping member <NUM> thereby delimits an optically active and elastically expandable (e.g. circular) region 10c of the membrane <NUM>, wherein particularly said region 10c extends up to an (e.g. circumferential) inner edge of the lens shaping member <NUM>, and wherein particularly said region 10c comprises said curvature of the membrane <NUM> to be adjusted. The lens shaping member <NUM> may be formed as an annular (e.g. circular) frame for generating a spherical tunable lens, but may also have any other geometry (see above).

Further, the lens device <NUM> comprises an actuator means <NUM> that is shown in the detail on the right hand side of <FIG>. Said actuator means <NUM> is designed to generate an axial movement of the optical element with respect to an axial direction A running perpendicular to the plane defined by the lens shaping member <NUM>. Thus, the lens device <NUM> may be used in an autofocus application where the focus of the lens (i.e. the curvature of the membrane <NUM>) may be controlled as described before by moving the optical element <NUM> with respect to the lens shaping member <NUM> in the axial direction.

For this, besides said magnet <NUM>, the actuator device <NUM> comprises a coil <NUM> that is carried by an annular coil frame <NUM> that faces the second side 300b of the magnet <NUM> and is coaxially arranged with respect to the magnet <NUM>. The lens shaper <NUM> is connected to the coil frame <NUM>, particularly integrally, and protrudes from the coil frame <NUM> towards the membrane <NUM> so as to contact it as described above. Further, the coil frame <NUM> surrounds a recess being aligned with the recess <NUM> of the magnet <NUM>, so that light can pass the volume V and the coil frame <NUM> in the axial direction A.

As shown in <FIG>, particularly on the lower left hand side, the coil <NUM> extends circumferentially in the coil frame <NUM> and also extends along the magnet <NUM> (coaxially with the magnet <NUM>) and faces the second side 300b of the latter so that the magnet <NUM> is arranged between the coil <NUM> and the magnetic flux return structure <NUM>.

Further, in the embodiment shown in <FIG> and in the lower left hand side of <FIG> as well as in the upper left hand side of <FIG>, the coil <NUM> comprises a conductor that is wound around a coil axis that coincides with the axial direction A (i.e. runs perpendicular to said plane or to said lens shaping member <NUM>), wherein the coil <NUM> comprises an outer first section <NUM> surrounding an inner second section <NUM> of the coil <NUM>, wherein the conductor is wound around said coil axis such that each of said two sections <NUM>, <NUM> of the coil <NUM> extends along the magnet <NUM> and faces the second side 300b of the magnet <NUM>. Now, as indicated in <FIG> on the lower left hand side, in said first section <NUM> the conductor has a winding direction that is opposite to the winding direction of the conductor in the second section <NUM> of the coil <NUM>, so that when a current is applied to the coil <NUM>, the current flows in one direction in the first section <NUM> (out of the plane of projection) and in the opposite direction in the second section <NUM> (into the plane of projection) of the coil <NUM>. This generates a Lorentz force that causes the magnet <NUM> and the coil <NUM> to attract each other or to repel each other in a very efficient manner as indicated on the right hand side of <FIG>, depending on the direction of the current in said sections <NUM>, <NUM> of the coil <NUM>. By means of such a magnet-coil configuration, the optical element <NUM> can be moved towards and away from the lens shaping member <NUM> in the axial direction A, i.e. for increasing the curvature of the membrane <NUM> so as to alter the focus of the lens as indicated in <FIG> in the upper middle panel for instance.

A modification of this magnet-coil configuration is shown on the lower right hand side of <FIG>. This modification also allows to - besides moving the optical element axially as it is needed for instance when the lens device <NUM> is used as an autofocus lens - to tilt the optical element <NUM> with respect to said plane (i.e. the lens shaping member <NUM>). In this modification, instead of a single magnet <NUM>, the actuator means <NUM> of the lens device <NUM> comprises a plurality of magnets <NUM>, e.g. three magnets <NUM> as shown on the lower right hand side of <FIG>, which are arranged along the annular return structure <NUM>, namely around the volume V, so that they are e.g. evenly spaced along the periphery of the return structure <NUM> or volume V (or in other words arranged around the central axis A of the optical device <NUM>). All three magnets <NUM> are magnetized in the axial direction A. Here, each magnet <NUM> comprises a first and a second side 303a, 303b which second side 303b faces away from the first side 303a, wherein the return structure <NUM> is connected to the first side 300a while the membrane <NUM> is attached to the second sides 303b of the magnets <NUM>. The magnets <NUM> may be embedded into the return structure <NUM> or the latter may simply be connected to the first sides 303a of the magnets <NUM>. The magnets <NUM> form part of a wall member <NUM> that surrounds the fluid filled volume V of the lens. As indicated on the lower right hand side of <FIG>, the second sides 303b of the magnets <NUM> may further each comprise a certain contour such as an elongated curved contour which follows the contour of a section of the annular (circular) return structure <NUM> to which the respective magnet <NUM> is attached.

Now, instead of a single coil <NUM>, the lens device <NUM> comprises a plurality of coils <NUM> (here e.g. three coils <NUM>) corresponding to the number of magnets <NUM>, wherein each coil <NUM> of the plurality of coils is associated to a different magnet <NUM>, wherein the respective coil <NUM> faces the associated magnet <NUM> in the axial direction A.

Particularly, each of said coils <NUM> comprises an outer contour that mimics the contour of the second side 303b of the associated magnet <NUM>, e.g., each coil may comprise an elongated, curved contour, so that in an outer half 403a of the respective coil <NUM> the current flows in a first direction along the associated magnet <NUM> while it flows in the opposite direction in the other inner half 403b of the respective coil <NUM>. Thus, when a current is applied to one of the coils <NUM>, a Lorentz force is generated that causes the associated magnet <NUM> and said coil <NUM> to attract each other or to repel each other depending on the direction of the current in said coil <NUM>. This allows to tilt the optical element <NUM> with respect to a plane spanned by the lens shaping member <NUM> or with respect to the lens shaping member <NUM> itself, which allows one to give the volume V under the optical element <NUM> the form of a prism, such that light that passes the volume V is deflected as indicated in <FIG> in the upper right hand panel. This can be employed e.g. for image stabilization as described above. Of course, in case all coils <NUM> are actuated in a symmetric fashion, the curvature of the membrane <NUM> can be altered in addition due to an axial movement of the optical element <NUM> with respect to the lens shaping member <NUM> so that an autofocus function can be combined with image stabilization.

Unless not stated otherwise, the above described magnet-coil configurations (single coil and single magnet as well as multiple coils and magnets) can both be applied to the embodiments that will be described below. Furthermore, it is also possible to have a configuration with a single magnet and multiple coils.

<FIG> shows a modification of the embodiments shown in <FIG> and <FIG>, wherein in addition to these embodiments, the lens device <NUM> according to <FIG> comprises an annular field guiding plate <NUM> that is arranged coaxially with respect to the coil frame <NUM> on a side of the coil frame <NUM> that faces away from the magnet <NUM>. When the magnet <NUM> is moving down towards the coil <NUM> due to the Lorenz force created by a current through the coil <NUM>, the magnet <NUM> starts to get attracted more and more to the field guiding plate <NUM>. This attractive force helps to deform the membrane <NUM>, supporting the Lorenz force and therefore makes the lens device <NUM> more efficient. Furthermore, the field guiding plate <NUM> also helps to magnetically shield the device <NUM>.

<FIG> shows a further lens device <NUM>. Here, in contrast to <FIG>, the annular magnet <NUM> to which first side 300a the return structure <NUM> is connected is connected to the lens shaping member <NUM> which protrudes downwards from the magnet <NUM> towards the membrane <NUM> and contacts the membrane <NUM> from above, which membrane <NUM> in turn is connected to a circumferential wall member <NUM> which also carries the coil <NUM> (or coils <NUM>) that face the second side 300b of the magnet <NUM>. Here, the circumferential wall member <NUM> together with the membrane <NUM> and the optical element <NUM> which is connected to or an integral part of the wall member <NUM> (e.g. a multi-layer printed circuit board) on a side facing away from the side of the wall member <NUM> to which the membrane <NUM> is connected, form a container of volume V for the fluid F. For detecting a movement of the magnet <NUM> that may be used for controlling the actuator means <NUM> as described above, a Hall sensor <NUM> is provided that may be arranged on the wall member <NUM>. In the embodiment shown in <FIG>, the magnet <NUM> and the lens shaping member <NUM> connected thereto is axially moved and/or tiled by the actuator means with respect to the optical element <NUM> as described above, while in <FIG> it is the other way around.

<FIG> shows a modification of the device shown in <FIG>, wherein in contrast to <FIG>, the coil <NUM>, being a coil of uniform winding direction, is arranged on the first side 300a of the annular magnet <NUM>, while the return structure is arranged on the second side 300b of the magnet <NUM>. Here, the coil <NUM> is connected to the return structure <NUM> via an axially extending spacer <NUM> that surrounds the magnet <NUM>.

Further, <FIG> shows a modification of the device shown in <FIG>, wherein the return structure <NUM> is omitted and the lens shaping member <NUM> is formed by the annular magnet <NUM> itself.

<FIG> shows four different ways of arranging magnets <NUM> and coils <NUM> with respect to the membrane <NUM> in a configuration with one deformable membrane <NUM> and two liquid volumes V, V'. By selecting two liquids F, F' with different refractive indices but similar density, a gravity insensitive lens can be built.

<FIG> shows the configuration shown in <FIG> on the lower left hand side in detail. Here, the membrane <NUM> is arranged between an annular top lens shaping member 11a contacting the membrane <NUM> from above and an (e.g. identical) bottom lens shaping member 11b contacting the membrane <NUM> from below. The membrane <NUM> is further held between a circumferential top spacer <NUM> and a circumferential bottom spacer <NUM>, wherein an optical element <NUM> in form of a transparent top glass <NUM> is connected to the top spacer <NUM>, so that the top spacer <NUM>, the top glass <NUM>, and the membrane <NUM> form a (top) volume V being filled with a (top) fluid F, and wherein a further optical element <NUM> in the form of a transparent bottom glass <NUM> is connected to the bottom spacer <NUM>, so that the bottom spacer <NUM>, the bottom glass <NUM>, and the membrane <NUM> form a (bottom) volume V being filled with a (bottom) fluid F'. Now, in order to deform the membrane <NUM> according to the principles described above, the top lens shaping member 11a is connected to an annular top magnet <NUM> residing in the volume V, and the bottom lens shaping member 11b is connected to an annular bottom magnet <NUM>' that faces the top magnet <NUM> in the axial direction A and is arranged coaxially with respect to the top magnet <NUM>, wherein the two lens shaping members 11a, 11b are arranged between the two magnets <NUM>, <NUM>' in the axial direction A. Furthermore, the two magnets <NUM>, <NUM>' are axially magnetized (in the axial direction A). Here, each of the magnets <NUM>, <NUM>' can be actuated with an associated coil, namely top coil <NUM>, and bottom coil <NUM>', which may each be arranged on or embedded into a printed circuit board (PCB), wherein the top coil <NUM> associated to the top magnet <NUM> may be arranged on the top glass <NUM> so that it faces the top magnet <NUM>, and wherein the bottom coil <NUM>' associated to the bottom magnet <NUM>' can be arranged on the bottom glass <NUM> so that it faces the bottom magnet <NUM>'. Particularly, the magnets <NUM>, <NUM>' and associated coils <NUM>, <NUM>' can be configured as described above with respect to <FIG> and <FIG>. In case the top and bottom coil <NUM>, <NUM>' are connected such that both coils <NUM>, <NUM>' cause the magnets <NUM>, <NUM>' to move up or down, a very efficient actuation of the magnets can be achieved.

Further, <FIG> shows a modification of the device shown in <FIG>, wherein in contrast to <FIG>, the top magnet <NUM>, top lens shaping member 11a and the top coil <NUM> are omitted.

<FIG> shows the configuration shown on the lower left hand side of <FIG> in detail. Here, the annular lens shaping member <NUM> contacting the membrane <NUM> from above also functions as a coil frame for carrying the coil <NUM> which is embedded into the lens shaping member <NUM>. In order to provide electrical connections to the coil(s) <NUM>, the lens shaping member <NUM> is connected to a contact spring <NUM> via which the lens shaping member is connected to a circumferential top spacer <NUM> and to a circumferential bottom spacer <NUM>. Further, in the axial direction A, the lens shaping member/coil frame <NUM> is arranged between an annular top magnet <NUM> and an annular bottom magnet <NUM>', wherein the top magnet <NUM> is connected to a top return structure <NUM> which in turn is connected to a top glass <NUM> that is connected to the top spacer <NUM>, and wherein the bottom magnet <NUM>' is connected to a bottom return structure <NUM>' which in turn is connected to a bottom glass <NUM> that is connected to the bottom spacer <NUM>. The top magnet <NUM> and bottom magnet <NUM>' are both magnetized in the axial direction A. Now, a circumferential deformable top wall (e.g. in the form of a top bellows) <NUM> extends from the top magnet <NUM> towards the lens shaping member <NUM> so that a top volume V is formed that is filled with a top fluid F and that is delimited by the top glass <NUM>, the top bellows <NUM> and the membrane <NUM>. Likewise, a circumferential deformable bottom wall (e.g. in the form of a bottom bellows) <NUM> extends from the bottom magnet <NUM>' towards the lens shaping member <NUM> so that a bottom volume V' is formed that is filled with a bottom fluid F' and that is delimited by the bottom glass <NUM>, the bottom bellows <NUM> and the membrane <NUM>.

In the devices having two volumes V, V' and fluids F, F' therein, the fluids can be different in refractive index but similar in density. Particularly, the further (bottom) fluid F' can be one of the fluids described above. The particular advantage of having two fluid-filled volumes and a membrane <NUM> there between is the fact that gravity induced coma can be almost completely removed and the lens is much less shock sensitive.

Also here, the lens shaping member <NUM> can be moved to deform the membrane <NUM> using the coil <NUM> and the magnets <NUM>, <NUM>' according to principles described above.

Claim 1:
Lens device, comprising:
- a transparent and elastically expandable membrane (<NUM>),
- a transparent optical element (<NUM>) facing the membrane (<NUM>),
- a wall member (<NUM>), wherein the optical element (<NUM>) and the membrane (<NUM>) are connected to the wall member (<NUM>) such that a volume (V) is formed,
- a fluid (F) residing in said volume (V) and completely filling it, and
- a lens shaping member (<NUM>) attached to the membrane (<NUM>),
characterized in that,
the lens shaping member (<NUM>) is attached to an outside (10a) of the membrane (<NUM>), which outside (10a) faces away from said volume (V), and wherein the lens device (<NUM>) comprises an actuator means (<NUM>) that is designed to move the optical element (<NUM>) in an axial direction (A) with respect to the lens shaping member (<NUM>) so as to adjust the pressure of the fluid (F) residing inside the volume (V) and therewith a curvature of said membrane (<NUM>), wherein said axial direction (A) is oriented perpendicular to a plane along which the lens shaping member (<NUM>) extends, and wherein said actuator means (<NUM>) is designed to tilt the optical element (<NUM>) with respect to said plane, so as to form the volume (V) into a prism for deflecting light passing through the volume (V), and wherein the actuator means (<NUM>) is designed to act on the wall member (<NUM>) for moving the optical element (<NUM>) axially and for tilting the optical element.