Controllable lens that operates via a flexure joint

Abstract

The present invention relates to a controllable lens with variable optical power, comprising first and second cover members (111, 112), a non-fluid body (105), one or more actuators, and one or more elastic elements (130, 130a, 1301, 1302), the non-fluid body (105) being transparent and deformable and sandwiched between the first and second transparent cover members, the first and second transparent cover members and the non-fluid body constituting a lens, the one or more actuators being arranged to provide a displacement in a direction parallel to the optical axis, the one or more elastic elements (130, 130a, 1301, 1302) connecting the actuator displacement elements to the first cover member, at least a portion of each of the one or more elastic elements being arranged to elastically deform in response to a relative radial displacement between the first transparent cover member and the actuator displacement elements.

Description

Technical Field

[0001] The present invention relates to a lens having a variable focal length, such as a variable lens for use in a compact camera.

Background Art

[0002] The use of variable focal length lenses in cameras and other electronic devices is very interesting because such lenses may replace a multi-lens system composed of motors for displacing the lens to achieve a variable focal length. Variable focal length lenses may be used to improve the performance of electronic devices and / or to reduce their size. There is still a need to improve the performance and quality of variable lenses, such as reducing the wavefront error performance of the lens.

Summary of the Invention

[0003] An object of the present invention is to improve a variable focal length lens. In particular, an object of the present invention is to provide a suitable actuator mechanism, which includes a method of transmitting the movement of the actuator to the lens membrane without causing deformation of the membrane that can cause aberration and wavefront error.

[0004] In a first aspect of the present invention, there is provided a controllable lens having a variable refractive power, the controllable lens comprising: a first cover member and a second cover member; a non-fluid body; one or more actuators; one or more elastic elements; and one of the first and second cover members is transparent, and the other of the first and second cover members is transparent or reflective. The non-fluid body is sandwiched between the first cover member and the second cover member, is transparent and deformable, and the first and second cover members and the non-fluid body constitute a lens having an optical axis intersecting the first and second cover members and the non-fluid body. The one or more actuators include a plurality of actuator displacement elements arranged to be displaced in a direction parallel or substantially parallel to the optical axis. The one or more elastic elements connect the actuator displacement elements to the first cover member. At least a part of each elastic member of the one or more elastic elements is arranged to elastically deform in response to a relative radial displacement between the first cover member and the actuator displacement element. Each of the one or more elastic elements has a first rigidity in the radial direction and a second rigidity in the direction of the optical axis. There is provided a controllable lens characterized in that the first rigidity is smaller than the second rigidity.

[0005] The rigidity of the elastic element may be an elastic rigidity such as the elastic coefficient of a spring or a viscoelastic rigidity. The rigidity is given by a combination of the dimensions of the elastic element and the elastic material properties such as the Young's modulus of the material. The first and second rigidities give the relationship between the deformations in the radial and axial (along the optical axis) directions and the radial force or torque causing the radial deformation and the axial force causing the axial deformation.

[0006] Preferably, by connecting the actuator output to the cover member, i.e., the lens membrane, by an elastic connection element that can be designed to elastically deform at least radially in response to bending of the cover member, the change in the radial elongation of the cover member caused by the actuator is accumulated by the elastic element. It is understood that due to the relative radial displacement, at least one component of the relative radial displacement has a direction perpendicular to the optical axis in the radial direction.

[0007] The elastic element has a structure with a bendable shape designed to bend in the radial direction, i.e., towards the optical axis. However, if by design the first or radial rigidity is less than the second or axial rigidity, in the axial direction along the optical axis, the structure is difficult to bend, cannot be bent, or allows only slight compression or tension.

[0008] Elastic deformation may include radial deformation towards the optical axis and rotational deformation in the rotational direction due to torque. The radial deformation includes deformations in the range of 0.1 μm to 250 μm, 0.1 μm to 50 μm, 0.5 μm to 50 μm, 1 μm to 25 μm, 2 μm to 500 μm, 5 μm to 500 μm, 5 μm to 250 μm, 7 μm to 150 μm, etc., and deformations in the range of 0.05 μm to 500 μm.

[0009] The first cover member is a first transparent cover member, and the second cover member is either a second transparent cover member or a second reflective cover member. Alternatively, the first cover member is either a first transparent cover member or a first reflective cover member, and the second cover member is a second transparent cover member.

[0010] According to one embodiment, each of the elastic elements is arranged to elastically deform in response to torque around an axis in contact with a path circumscribing the optical axis, and the torque is generated by a relative radial displacement between the first cover member and the actuator displacement element.

[0011] Preferably, the elastic element can support the rotational component with low elastic resistance due to the bending of the first cover member.

[0012] According to one embodiment, each elastic element has a first portion fixed to the first cover member and a second portion fixed to the actuator displacement element or fixed to at least one of the actuator displacement elements, and the first and second portions are elastically connected by portions of the elastic element arranged to elastically deform in response to relative radial displacement.

[0013] Preferably, the fixed connection provides a rigid connection that enables the movement of the actuator to be efficiently transmitted to the first cover member.

[0014] The first and second portions may be elastically connected via associated elastic portions of one or more elastic elements arranged to elastically deform. The first and second portions can form a more rigid portion of the elastic element, such as a portion that does not deform or deforms less, for example, in response to a relative radial displacement between the first transparent cover member and the actuator displacement element. Thus, the first and second portions can be distinguished from the elastic portions of the elastic element with respect to elasticity, such as a lower elasticity (higher rigidity) with respect to the relative radial displacement between the first transparent cover member and the actuator displacement element.

[0015] According to one embodiment, the first portion of the elastic element is distributed along a path circumscribing the optical axis and is connected to the first cover member at a remote location thereof.

[0016] For example, one or more actuators may be arranged to generate a force along a path circumscribing the optical axis of the first cover member in order to generate a controllable change in the curvature of the first and / or second cover member.

[0017] According to one embodiment, each of the elastic elements comprises a first spring constant in the radial direction and a second spring constant in the direction of the optical axis, and the first spring constant is smaller than the second spring constant.

[0018] According to one embodiment, the controllable lens comprises one or more other elastic elements that connect the actuator displacement element to the second cover member.

[0019] Thus, the controllable lens can comprise a first elastic element and a second elastic element arranged to face the first and second cover members, respectively.

[0020] According to one embodiment, each elastic element includes an elastic adhesive. Alternatively or additionally, the elastic element includes a non-metallic material or a viscoelastic material, and the elastic adhesive is an example thereof.

[0021] Advantageously, the adhesive (glue) or the adhesive (adhesive) may be used as an elastic component or in combination with other types of elastic components such as elastic hinges, flexure structures, and other spring elements.

[0022] According to one embodiment, each elastic element includes one or more spring elements, and each spring element includes a first portion.

[0023] According to one embodiment, each elastic element includes a support member, and the support member includes a second portion. The support member is provided as a common support for a plurality of actuator displacement elements and / or for a plurality of elastic portions of each of one or more elastic elements.

[0024] Thus, a support member such as a force distribution support member may be connected to a plurality of elastic portions such as a plurality of actuator displacement elements and / or spring elements. According to one embodiment, each of the spring elements is structured as an individual spring element. Thus, each spring element can deform independently of other spring elements.

[0025] According to one embodiment, the support member is located closer to the optical axis in the radial direction than the spring element.

[0026] According to one embodiment, the controllable lens includes a first elastic element connecting an actuator displacement element to a first cover member and a second elastic element connecting another actuator displacement element constituted by the controllable lens to a second cover member.

[0027] According to one embodiment, each of the elastic elements includes one or more spring elements and an elastic material such as an elastic adhesive connected to the first and / or second portions.

[0028] Preferably, the combination of the spring element and other elastic materials can improve the ability of the elastic element to provide low stiffness in response to radial deformation and rotation, such as rotation about an axis circumscribing the circumference of the lens. At the same time, for example, along the optical axis, high stiffness is provided in the displacement direction of the actuator displacement element.

[0029] A second aspect of the present invention relates to an electronic device comprising the controllable lens described in the first aspect. For example, the electronic device may be a camera module or other device as described in the description.

[0030] The electronic device includes a control system for supplying and controlling power to one or more actuators to generate a controllable change in the refractive power of the lens. The control system may be configured to shift between predetermined refractive powers of the lens. The control system is arranged to generate a control signal or a power signal, and optionally to acquire measurement data for determining the control signal or the power signal, and to control the actuator using a feedforward or feedback control algorithm based on the measurement data and a reference value such as a desired refractive power of the lens, and may include an electronic circuit and / or a digital processor.

[0031] A third aspect of the present invention relates to the use of the controllable lens described in the first aspect for imaging, light irradiation, light beam scanning, light detection, and other purposes.

[0032] In general, the various aspects and embodiments of the present invention can be combined or combined in any way possible within the scope of the present invention. These and other aspects, features and / or advantages of the present invention will become apparent and understood with reference to the embodiments described below.

Brief Description of the Drawings

[0033] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1A

Figure 1B

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Figure 2B

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Figure 4C

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Figure 8

DETAILED DESCRIPTION OF THE INVENTION

[0034] Figures 1A and 1B show a side view and a top view of a controllable variable focal length lens 100.

[0035] The lens 100 includes a first cover member 111 and a second cover member 112. At least one of the first and second cover members is configured to be bent by a force provided by an actuator. In one example, both the first and second cover members 111, 112 are transparent cover members, such as made of glass or plastic.

[0036] Instead of the two transparent cover members 111, 112, either the first or the second cover member may be reflective, for example, having a reflective metal layer, thereby providing complete or partial reflection and causing the incident light beam to be reflected back to the opposite transparent cover member. For convenience, the examples and embodiments in this specification refer to the transparent cover members 111, 112.

[0037] The lens 100 includes a transparent and deformable non-fluid body 105 sandwiched between the first and second transparent cover members 111, 112. The non-fluid body 205 contacts the inner surfaces of the first and second cover members 111, 112.

[0038] The first and second transparent cover members 111, 112 and the non-fluid body 105 constitute a lens having an optical axis 150 that intersects the first and second transparent cover members and the non-fluid body. The optical axis may be defined as an axis passing through the centers of the first and second transparent cover members 111, 112 and the non-fluid body 105 and perpendicular to a plane of one of the cover members. The optical axis may be defined according to conventional optical definitions.

[0039] The transparent deformable non-fluid lens body 105 is preferably made of an elastic material. Since the lens body is non-fluid, a fluid-tight container for encapsulating the lens body to prevent leakage from the lens body is not necessary. In a preferred embodiment, the lens body may be composed of a soft polymer including many different materials such as silicone, polymer gel, a polymer network of cross-linked or partially cross-linked polymers, and a combination of miscible oils or oils. The elastic modulus of the non-fluid lens body may be greater than 300 Pa, thereby avoiding deformation due to gravity during normal operation. The refractive index of the non-fluid lens body may be greater than 1.3. The non-fluid body 205 may have a refractive index equal to, substantially equal to, or close to that of the first and second cover members 111, 112 in order to reduce reflection at the boundary of the non-fluid body 105.

[0040] The transparent cover members 111, 112 may be made of many different materials such as acrylic, polyolefin, polyester, silicone, polyurethane, glass, etc. At least one of the first and second cover members 111, 112 arranged to be deformed by the actuator has a rigidity suitable for allowing it to be bent by the operation of the actuator 121. Generally, the first and / or second cover members 111, 112 may be formed of a material having a Young's modulus in the range of 5 MPa to 100 GPa in order to provide the required rigidity. For example, the Young's modulus of borosilicate glass is 63 GPa, and the Young's modulus of fused silica glass is 72 GPa.

[0041] The bending of the first and / or second cover members 111, 112 is at least partially due to the radially varying reaction force from the lens body 105, which affects the sag of the cover members 111, 112 and thus affects the refractive power rather than simply compressing the lens body vertically without changing the sag. A complete explanation of the effect of the lens body 105 on the curvature of the cover member is described in International Publication No. WO 2019 / 002524, which is incorporated herein by reference.

[0042] The lens 100 further includes one or more actuators 121 having a plurality of actuator displacement elements 122 arranged to displace in a direction parallel or substantially parallel to the optical axis 150.

[0043] One or more actuators 121 are arranged to generate a force on the first or second cover member 111, 112 along a path 151 surrounding the optical axis 150, such as a circle on the surface of the first or second cover member 111, 112. One or more actuators may be arranged such that the displacement element acts on an outward or inward surface as shown for one or both of the first and second cover members 111, 112.

[0044] For example, the actuator 121 may be a linear displacement actuator such as a linear piezoelectric motor or an electromagnetic motor, a piezoelectrically actuated cantilever actuator, a shape memory alloy, a linear screw drive, or a linear voice coil actuator, arranged to apply displacement at several points along the path 151, here eight points.

[0045] In one example, the elastic element 130 is configured as a ring or toroid of adhesive surrounding the optical axis, disposed, for example, along path 151. A force distribution ring, such as a metal ring or a ring made of another sufficiently rigid material, is disposed over the circular adhesive ring so that the ring does not bend or substantially bend axially. The force distribution ring may be embodied by support member 302 (see description of support members elsewhere). Two or more displacement elements (actuated by one or more actuators) are disposed to axially displace the force distribution ring and bend the first or second cover member. In this example, the ring-shaped elastic element 130 formed of elastic adhesive has an axial thickness in the range of 0.05 mm to 0.2 mm, such as 0.1 mm, and a toroid body width in the range of 0.1 mm to 0.5 mm, such as 0.2 mm (the difference between the inner radius and the outer radius, i.e., the thickness of the ring). The stiffness of the adhesive, expressed as Young's modulus, may be in the range of 2 to 200 MPa, such as 25 MPa when cured or solidified.

[0046] In one example, the actuator is fixed to the static support 190 such that the displacement element 122 displaces relative to the support 190. Similarly, an unactuated cover member, such as the second cover member 112 shown in FIGS. 2A-2B, may be supported by the static support 190 unless the second cover member 112 is actuated by another actuator displacement element 122 of another actuator 121.

[0047] In an example where one or more actuators are arranged to act on the inner surfaces of the first and second cover members 111, 112, the actuator 121 is connected to one of the cover members via an elastic element, and the actuator displacement element 122 is connected to the opposite cover member via an elastic element. In this way, the displacement of the actuator causes bending of both cover members. Alternatively, the actuator 121, i.e., the component configured to be stationary, is fixed to the static support 190, and the actuator displacement element 122 is connected to the inner surface of one of the first and second cover members 111, 112. The cover member not connected to the actuator displacement element may be connected to the static support 190.

[0048] The actuator may be arranged between the first cover member 111 and the second cover member 112, i.e., simply sandwiched between the first cover member 111 and the second cover member 112.

[0049] The path 151 may surround the transparent and deformable non-fluid body 205 such that the non-fluid body 205 is surrounded by the path 151 as shown. However, the path 151 can also be arranged within the extension of the non-fluid body 205. The actuator 121 can also be arranged to act on or be positioned close to the edge of the first or second cover member 111, 112.

[0050] The actuator 121 is arranged to generate a displacement in a direction perpendicular or substantially perpendicular to the surface of the cover members 111, 112 along the path 151. In this context, substantially perpendicular may mean that the deviation from perpendicularity is at most 10 to 15 degrees. The angular variation of the angle between the direction of the linear displacement and the surface of the cover member is generated depending on the bending of the cover member.

[0051] As will be described in more detail below, the operation of the actuator changes the curvature of the first and / or second cover members in response to the force, torque, or displacement provided by the actuator. In this way, by controlling the actuator, bending, i.e., the refractive power of the lens 100, can be controlled. When the actuator is connected and disposed to the first cover member, the second cover member can also bend, and depending on the thickness or rigidity of the cover member, the reverse is also possible. Although the actuator can be disposed in relation to the first cover member 111, the first cover member 111 is highly rigid, and due to the displacement of the actuator acting on the first cover member 111, mainly the second cover member 112 is bent. In this case, the second cover member 112 may be supported by the static support 190.

[0052] In addition, the actuator 121 can be disposed to act on either the first or second cover member 111, 112. It is also possible to dispose the actuator 121 to act on both the first and second cover members 121, 122, so that both cover members are forced to bend by the action of the actuator 121, or perhaps so that the actuator on either side can be independently controlled, i.e., the displacement / force applied to one of the cover members is independent of the displacement / force applied to the other.

[0053] The actuator displacement element 122 of the actuator 121 is connected to the first transparent cover member 111 via the elastic element 130.

[0054] The elastic element 130 elastically deforms in response to the relative displacement between the first transparent cover member 111 and the actuator displacement element 122.

[0055] According to one embodiment, the elastic element 130 includes an elastic material such as an elastic adhesive. Thus, the elastic connection between each of the actuator displacement elements 122 and the cover members 121, 122 can be achieved, for example, by performing an adhesion process such as applying a specific amount of adhesive to ensure that a specific distance and orientation between the actuator displacement element 122 and the cover members 111, 112 are maintained during the curing of the adhesive.

[0056] For example, a single elastic element 130 made of an elastic adhesive connecting a single actuator displacement element 122 to one of the cover members 121, 122 is formed as a cylindrical element such as a barrel shape, and may have, for example, an axial (along the optical axis) thickness in the range of 0.01 mm to 1 mm, and a width or radius perpendicular to the axial direction (i.e., radial) in the range of 0.02 mm to 2 mm. The stiffness of the adhesive expressed in terms of Young's modulus may be in the range of 2 to 200 MPa, such as 25 MPa.

[0057] Generally, the elastic adhesive connection may have a thickness in the range of 0.01 to 5.00 mm, a radial width in the range of 0.02 to 2.00 mm, and may be made of an adhesive having a Young's modulus in the range of 1 to 1000 MPa.

[0058] FIG. 2A shows the deformation ability of one of the elastic elements 130. The stationary xyz coordinate system is defined with respect to the initial position of the elastic element 130, for example, when the elastic element 130 is in an undeformed state. In this example, the z-axis is parallel to the optical axis 150.

[0059] In the left figure, the first cover member 111 has an initial curvature. The initial curvature may be due to a preformed curvature or the initial displacement of the actuator displacement element 122. The contact point 281 on the first cover member 111 has xz coordinates x0, z0 at the interface between the elastic element 130 and the first cover member 111.

[0060] In the right figure, the actuator 121 is controlled to move or extend the actuator displacement element 122 by a distance ΔL1 along the z-axis. Due to this displacement, bending or additional bending of the first cover member 111 occurs, and the radial displacement of the contact point 281 towards the optical axis, that is, the displacement along the x-axis of the local xyz coordinate system, and the displacement along the z-axis cause the contact point 281 to move from x0, z0 to x1, z1.

[0061] Due to the bending of the first transparent member 111, the surface at the interface between the elastic element 130 and the first cover member 111 rotates about the y-axis, that is, generally rotates about an axis that contacts the path 151 circumscribing the optical axis 150.

[0062] As shown in the figure, the elastic element 130 is configured to elastically deform radially along the x-axis here in response to the relative radial displacement between the first transparent cover member 111 and the actuator displacement element 122.

[0063] Furthermore, the elastic element 130 is configured to elastically deform in response to the torque Ty acting about the y-axis or the tangent axis. The torque Ty is generated by the bending of the first transparent member 111 including rotation about the y-axis, or generally by the relative displacement between the first transparent cover member and the actuator displacement element.

[0064] Preferably, the elastic element 130 has a low rigidity in response to radial deformation and in response to rotation such as rotation about the tangent axis, here the y-axis. It is preferable to have a low rigidity in order to be able to bend the first transparent member 111 without being exposed to surface stresses that could inappropriately affect the curvature of the first transparent member 111, whereby the corrected curvature increases the wavefront error. Undesirable stresses are considered to be due to, for example, forces and torques from the elastic element 130 acting in the radial direction and about the tangent axis or the y-axis.

[0065] On the one hand, in order to transmit the actuator displacement to the cover member, the elastic element preferably has high rigidity along the displacement direction of the actuator displacement element 122, that is, along the z-axis or the optical axis 150.

[0066] Accordingly, according to one embodiment, the elastic element has a first spring constant k1 in the radial direction and a second spring constant k2 in the direction of the optical axis 150, and the first spring constant k1 is greater than the second spring constant k2.

[0067] The following table shows examples of the magnitude of deformation related to the generated refractive power and diameter of the first or second transparent cover member 111, 112. The diameter can be specified as the distance between the actuator displacement elements 122 facing each other in the diameter direction. The bending height specifies the distance from the apex of the curved cover members 111, 112 to the non-deformed cover member.

[0068]

Table 1

[0069] Therefore, the values in the table show examples of deformation in the radial direction and the rotational direction of the elastic element 130.

[0070] The elastic element 130 can be defined as having a first portion 201 fixed to the first or second transparent cover member (for example, the surface in contact with the cover member 111 in FIG. 2A) and a second portion 202 fixed to the actuator displacement element (for example, the surface in contact with the actuator displacement element 122 in FIG. 2A). The first and second portions 201, 202 are elastically connected such that the first and second portions 201, 202 can be elastically displaced relative to each other, for example, from the radial direction towards the optical axis. The elastic element 130 may be monolithically manufactured from an elastic material such as silicone, polymer, metal, plastic, and other materials.

[0071] As shown in FIG. 1B and other examples of this specification, the first portion 201 of the elastic element 130 is connected to the first transparent cover member at discrete positions distributed along a path circumscribing the optical axis.

[0072] In general, one or more elastic elements 130 should be configured to allow for radial deformation at a given location, namely the location of the actuator displacement element 122, and be independent or substantially independent of the deformation of other elastic elements 130 at other locations. Thus, at least a portion of one or more elastic elements 130, such as the first portion 201, should be arranged to displace independently or substantially independently of the first portion 201 at other locations. Clearly, this is achieved when individual elastic elements 130 are used for each actuator displacement element 122 as shown in FIG. 1A. However, this objective is also achieved when the elastic element 130 is composed of a plurality of deformable portions, such as a plurality of first portions 201, which are not individually and independently connected to the corresponding plurality of actuator displacement elements 122.

[0073] FIG. 2B shows an alternative solution for avoiding the generated stress in the first or second cover member 111, 112. According to this alternative solution, the controllable lens 100 is configured with a sliding contact 239 instead of the elastic element 130.

[0074] The sliding contact 239 may be realized by a low-friction contact between the actuator displacement element 122 and the first or second cover member 111, 112. The low-friction contact can be realized by a pair of low-friction materials, such as the material of the contact portion of the actuator displacement element 122 that provides low friction or sufficiently low friction against the surface of the first or second cover member 111, 112. Examples include polyethylene and other plastic materials. Thus, the sliding contact 239 does not necessarily have to be composed of separate elements and may be composed of a direct contact between the actuator displacement element 122 and the first or second cover member 111, 112. Alternatively, the sliding contact may be realized by a low-friction material attached to the end of the actuator displacement element 122.

[0075] The sliding contact 304 is configured such that as the cover member bends due to the displacement ΔL1 of the actuator displacement element 122 along the z-axis, the sliding contact 239 can slide on the surfaces of the first and second cover members 111, 112. In this example, due to the displacement, a bend or additional bend occurs in the first cover member 111, and the contact point 281 moves from x0, z0 to x1, z1 due to the radial displacement of the contact point 281 towards the optical axis, i.e., the displacement along the x-axis of the local xyz coordinate system, and also due to the displacement along the z-axis. As shown in FIG. 2B, during bending, the sliding contact 239 slides on the surface of the cover member.

[0076] Figs. 3A - 3C show an example of an elastic element 130 composed of a plurality of deformable parts in the form of a plurality of spring elements 301.

[0077] The spring element 301 includes a first portion 201. For example, the first portion 201 may be embodied by the end face of a cantilever structure that embodies the spring element. In response to the bending of the first or second cover member 111, 112, the cantilever structure bends. The bending of the cantilever structure includes a combination of the inclination of the cantilever towards the optical axis and the rotation of the cantilever. Thus, the bending of the cantilever spring 301 facilitates the requirements of the elastic element 130 and provides a low rigidity corresponding to the radial deformation and a low rigidity corresponding to the rotation such as the rotation about the tangential axis or the y-axis.

[0078] Each of the spring elements 301 is separated from the adjacent spring elements so that each of the spring elements 301 can deform independently or substantially independently from the adjacent spring elements 301. Thus, the spring elements are configured as individual spring elements.

[0079] The elastic element comprises a support member 302. As mainly illustrated, the actuator displacement element 122 is arranged to act on the surface of the support member 302. Accordingly, the support member 302 comprises a second portion 202 and is configured as a common support for a plurality of displacement elements 122. That is, the plurality of displacement elements 122 are arranged to act jointly on the support member 302. That is, the displacements of the displacement elements 122 are transmitted to the support member together.

[0080] Alternatively or additionally, the support member 302 comprising the second portion 202 is configured as a common support for a plurality of spring elements 301, or generally, a plurality of elastic portions (such as elastic adhesive portions) of the elastic element 130 are arranged to act together on the support member 302. That is, the plurality of spring elements 301 or elastic portions are connected to the support member 302 together. That is, the reaction forces of the spring elements 301 or elastic portions are transmitted to the support member together.

[0081] In this example, the second portion 202 constitutes a portion of the elastic element 130 that is more rigid, that is, a portion such as an end having an elastic coefficient at least higher than the radial elastic coefficient k1 of the elastic portion of the elastic element 130. Similarly, the first portion 201 can also constitute a more rigid portion of the elastic element 130.

[0082] In this example, the support member 302 is formed as a ring-shaped structure having a hole that constitutes an aperture for the lens 100.

[0083] The elastic element 130 shown in FIGS. 3A - 3C can be formed monolithically. In another example, the spring element 301 is made of a material different from that of the support member.

[0084] In this example, the first and second cover members 111, 112 are operated independently via the upper first elastic element 130 and the lower second elastic element 130a, respectively.

[0085] Figures 4A to 4D show another example of the elastic element 130 composed of a plurality of spring elements 301.

[0086] As shown in FIGS. 4B and 4D, the spring element 301 is formed as a U-shaped element. The end portion of the spring element 301 includes a first portion 201.

[0087] Due to the U-shaped design of the spring element 301, radial movement and y-axis inclination (see FIG. 2) of the contact point, i.e., the first portion 201, are possible. The cross-sectional thickness of the spring element 301 can vary from the first portion 201 to the second portion 202 in order to achieve the desired characteristics of the first and second spring constants k1, k2. The thickness t (FIG. 4C) of the spring element 301 in the direction of the optical axis 150 can make the spring constant k2 in the optical axis direction larger than the radial spring constant k1. Also, the torsional spring constant around the y-axis (see FIG. 2) can be made sufficiently low with respect to the second spring constant k2.

[0088] The asymmetric design and the off-center position of the first portion 201 where the cover members 111, 112 are supported facilitate y-axis inclination. That is, when the first portion 201 receives pressure, the asymmetric design supports the inclination due to bending of the cover members 111, 112.

[0089] FIG. 4C shows that the elastic element 130 is formed as a flat structure, the end portion including the first portion 201 protrudes outward, and the first portion 201 is separated from the other portion of the elastic element 130 in the direction of the optical axis 150. The protruding first portion 201 enables the first and / or second cover members 111, 112 to be connected to the first portion 201, while the protruding first portion provides a clearance between the cover member and the elastic element 130.

[0090] In particular, the clearance provided by the protruding portion of the spring 301 such as the protruding first portion 201 allows the cover members 111, 112 to bend while still ensuring the clearance between the cover member and the inner circumference of the support member 302, and the minimum clearance occurs when the cover member is at its maximum.

[0091] Also in this example, the spring element 301 is configured as an individual spring element.

[0092] In this example, a plurality of elastic elements 130_1, 130_2 are arranged such that the inner circumferences of the plurality of elastic elements 130_1, 130_2 form holes that constitute the aperture of the lens 100.

[0093] Each elastic element 130 may have one or more springs 301, but in this example, each elastic element 130 includes two springs 301. For example, as shown in FIGS. 3A - 3C, a single elastic element 130 is configured to form a hole that constitutes the aperture of the lens 100.

[0094] Similar to FIGS. 3A - 3C, each elastic element 130 includes a support member 302. The actuator displacement element 122 is connected to the support member 302 via a second portion 202 of the elastic element 130.

[0095] Therefore, in this example, each of the support members 302 is configured as a common support for the plurality of spring elements 301 or the elastic portions of the elastic elements 130. As shown, the actuator displacement element 122 is connected to the support member 302 on a one - to - one basis, but each of the support members 302 can alternatively be configured as a common support for a plurality of actuator displacement elements.

[0096] The support member 130 and other designs shown in FIGS. 4A - 4D may be monolithically formed by injection molding, 3D printing, or other methods, for example, as a MEMS structure.

[0097] The portion of the elastic element 130 that constitutes the support member 302 is located closer to the optical axis 150 in the radial direction than the spring element 301.

[0098] The elastic element 130 shown in FIGS. 3A-3C and FIGS. 4A-4D may be configured as follows. That is, the elastic element 130 may include, in addition to one or more spring elements 301, an elastic material such as an elastic adhesive connected to the first and / or second portions 201, 202, such that the first portion 201 is fixed to the actuator displacement element 122 via the adhesive and / or the second portion 202 is fixed to the first or second cover member 111, 112. A combination of a spring element 301 and an elastic material such as an adhesive provided to connect the first and / or second portions 201, 202 to the displacement element 122 and the cover members 111, 112 respectively can advantageously improve the deformation ability of the elastic element 130 in response to bending of the cover members 111, 112, thereby reducing the generation of stress in the cover members.

[0099] FIGS. 6A-6C show an alternative configuration of the elastic element 130. FIG. 6A shows that the elastic element 130 comprises a ring-shaped structure with a second portion 202. FIGS. 6A-6B mainly show that the actuator displacement element 122 is fixed to the second portion. The elastic element comprises a plurality of spring elements 301 configured as a hinge structure. The spring elements are fixed to the first cover member 111 via their first portions 101.

[0100] FIG. 6C shows a possible configuration of hinge structures 601, 602 formed by creating a thin thickness along the direction defining the hinge axis. The illustrated xyz coordinate system is defined with respect to a surface 202a fixed to the second portion 202 via the ring structure.

[0101] Therefore, the spring element 301 includes a first hinge structure 601 that defines a rotation axis that allows rotation about the y-axis or about an axis that contacts a path 151 circumscribing the optical axis 150. The first hinge structure 601 thus supports relative rotation about the y-axis between the first transparent cover member 111 and the actuator displacement element 122. In other words, the first hinge structure is arranged to elastically deform in response to a torque Ty about the y-axis generated by the relative displacement between the first transparent cover member and the actuator displacement element.

[0102] The spring element 301 further includes a second hinge structure 602 that defines a rotation axis that allows rotation about the z-axis and thereby supports it. The elongation of the spring element 301 along the y-axis and the z-axis rotation generate a radial movement of the second hinge structure 602, thereby supporting a relative radial displacement between the first transparent cover member 111 and the actuator displacement element 122.

[0103] Since the rotational stiffness of the first and second hinge structures 601, 602 depends on the stiffness of the material, it is designed as needed, but clearly has limitations. Similarly, by designing the first and second hinge structures 601, 602 to have a sufficiently long length along the hinge axis, the hinge structure can be designed to have high stiffness in the z-axis direction.

[0104] Preferably, the rotations about the y-axis and z-axis provided by the first and second hinge structures 601, 602 provide decoupled rotations.

[0105] FIG. 7 shows another spring structure 301 that includes the first and second hinge structures 601, 602 and corresponds to FIG. 6C but allows a lower height along the z-axis. The two second hinge structures 602 in FIGS. 7 and 6C allow the first portion 201 of the spring element 301 to be displaced radially, i.e., in the x-direction, without rotation about the z-axis.

[0106] FIG. 8 summarizes the requirements for the elastic element 130. Thus, the left figure shows the elastic element 130 including the spring element 301 or a part of the elastic element when the actuator 121 is not generating a force, i.e., when F = 0. Thus, the first cover member 111 is in a state where its curvature has not been changed by the actuator.

[0107] In the right figure, the actuator displacement element operates to cause a z-axis displacement of ΔL1. The z-axis displacement generates a non-zero balancing force F1 in the z direction (i.e., the fixed bending state of the cover member) due to the reaction force at least partially caused by the bending of the first cover member 111. Due to the z-axis displacement generated by the actuator 121, the first cover member 111 bends as exaggeratedly shown. The bending causes, in addition to the z-axis displacement of ΔL1, a radial displacement of the first portion 201 along the x-axis and a rotation of the first portion 201 about the y-axis. Different examples of the elastic element 130 described herein provide the same reaction to the displacement of the actuator displacement element 122, i.e., provide a radial displacement and a rotation to support the bending of the first or second cover member 111.

[0108] FIG. 5 shows a cross-sectional view of an electronic device 500 such as a part of a smartphone, tablet, laptop, or other device. The device 500 may include a camera module 501 configured to image light onto an image sensor received via an aperture 502. The controllable lens 100 forms part of the camera module 501 and optionally forms other lenses and image sensors. Examples of the electronic device 500 include portable computers, smartphones, watches, tablets, cameras, glasses with variable lenses, measuring devices arranged to scan distances, and image projectors arranged to create images by scanning light beams. Thus, the lens 100 can be used for various purposes such as imaging, light and image projection, light beam scanning, and Lidar scanning.

Claims

1. A controllable lens (100) having a variable refractive power, the controllable lens comprising: a first cover member (111) and a second cover member (112); a non-fluid body (105); one or more actuators (121); one or more elastic elements (130, 130a, 130_1, 130_2); wherein one of the first and second cover members is transparent and the other of the first and second cover members is transparent or reflective; the non-fluid body (105) is sandwiched between the first cover member and the second cover member, is transparent and deformable, and the first and second cover members and the non-fluid body constitute a lens having an optical axis (150) that intersects the first and second cover members and the non-fluid body; the one or more actuators (121) are arranged to be displaced in a direction parallel to the optical axis and are provided with a plurality of actuator displacement elements (122) arranged to cause bending of at least the first cover member in response to the force provided by the one or more actuators; the one or more elastic elements (130, 130_1, 130_2) connect the actuator displacement elements to the first cover member; at least a portion of each of the one or more elastic elements is arranged to elastically deform in response to a relative radial displacement between the first cover member and the actuator displacement element (122) generated in response to the displacement of the actuator displacement element; each of the one or more elastic elements has a first rigidity in the radial direction and a second rigidity in the direction of the optical axis; the first rigidity is smaller than the second rigidity; the first rigidity enables radial deformation in the range of 0.05 μm to 500 μm; the controllable lens is configured such that a surface at an interface between the one or more elastic elements (130) and the first cover member (111) is rotated about an axis circumscribing a path (151) surrounding the optical axis (150) in response to displacement of the actuator displacement element (122) in a direction parallel to the optical axis and bending occurring in the first cover member. A controllable lens characterized by that.

2. Each of the one or more elastic elements is arranged to elastically deform in response to a torque (Ty) about an axis in contact with the path (151) surrounding the optical axis. The controllable lens according to claim 1, wherein the torque is generated by the relative radial displacement between the first cover member and the actuator displacement element. **Claim 3** Each of the one or more elastic elements comprises at least one first portion (201) fixed to the first cover member and a second portion (202) fixed to at least one of the actuator displacement elements. The controllable lens according to claim 1, wherein the first and second portions are elastically connected. **Claim 4** The controllable lens comprises a plurality of the first portions (201) of the one or more elastic elements (130). The controllable lens according to claim 3, wherein the first portion is distributed along a path (151) surrounding the optical axis and is connected to the first cover member (101) at a remote location thereof. **Claim 5** Each of the one or more elastic elements comprises a first spring constant (k1) in the radial direction and a second spring constant (k2) in the direction of the optical axis. The controllable lens according to claim 1, wherein the first spring constant (k1) is smaller than the second spring constant (k2). **Claim 6** The controllable lens according to claim 1, wherein the actuator displacement element (122) is arranged to be displaced relative to the static support by fixing the actuator to the static support (190). **Claim 7** The controllable lens according to claim 1, comprising one or more second elastic elements (130a) connecting the actuator displacement element (122) to the second cover member (112). **Claim 8** The controllable lens according to claim 1, wherein each of the one or more elastic elements comprises an elastic adhesive. **Claim 9** Each of the one or more elastic elements comprises at least one first portion (201) fixed to the first cover member and a second portion (202) fixed to at least one of the actuator displacement elements. Each of the one or more elastic elements (130) is one or more spring elements (301). The controllable lens according to claim 1, wherein each spring element comprises the first part (201).

10. The controllable lens according to claim 9, wherein each of the spring elements is configured as an individual spring element.

11. Each of the spring elements is configured as an individual spring element, each of the one or more elastic elements comprises a support member (302) provided as a common support for the plurality of actuator displacement elements (122) and / or for the plurality of elastic portions of each of the one or more elastic elements, The controllable lens according to claim 9, wherein the support member comprises the second part (202).

12. Each of the spring elements is configured as an individual spring element, each of the one or more elastic elements comprises a support member (302) provided as a common support for the plurality of actuator displacement elements (122) and / or for the plurality of elastic portions of each of the one or more elastic elements, the support member comprises the second part (202), The controllable lens according to claim 9, wherein each of the one or more support members is located closer to the optical axis in the radial direction than the spring element.

13. The controllable lens according to claim 1, comprising a first elastic element (130) connecting the actuator displacement element to the first cover member (111) and a second elastic element (130a) connecting the other actuator displacement element to the second cover member (112).

14. The controllable lens according to claim 3, wherein each of the one or more elastic elements comprises one or more spring elements (301) and an elastic material connected to the first and / or second parts (201, 202).

15. An electronic device comprising the controllable lens (100) according to claim 1.

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