Shape memory alloy actuator and method thereof

Abstract

An SMA actuator and related methods are described. One embodiment of the actuator includes a base, a plurality of buckle arms, and at least a first shape memory alloy wire coupled to a pair of the buckle arms. Another embodiment of the actuator includes a base and at least one bimorph actuator comprising a shape memory alloy material. The bimorph actuator is attached to the base.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION Embodiments of the present invention relate to the field of shape memory alloy systems, and more particularly, to the field of shape memory alloy actuators and related methods. [Background technology]

[0002] Shape memory alloy (SMA) systems have movable assemblies or structures that can be used, for example, with camera lens elements as autofocus drives. These systems can be surrounded by a structure such as a screening can. The movable assembly is supported for movement on a support assembly by bearings, such as a plurality of balls. A flexure element formed from a metal such as phosphor bronze, nickel-copper alloy, titanium-copper alloy, beryllium-copper alloy, or stainless steel has a movable plate and a flexure. The flexure extends between the movable plate and a stationary support assembly and acts as a spring to allow movement of the movable assembly relative to the stationary support assembly. The balls allow the movable assembly to move with little resistance. The movable and support assemblies are connected by four shape memory alloy (SMA) wires extending between the assemblies. Each of the SMA wires has one end attached to the support assembly and the opposite end attached to the movable assembly. The suspension is actuated by applying an electrical drive signal to the SMA wires. However, these types of systems suffer from system complexity, resulting in bulky systems that require large footprints and high clearances. Additionally, current systems are unable to provide a high Z stroke range in a compact, low-profile footprint. Summary of the Invention

[0003] An SMA actuator and related methods are described. One embodiment of the actuator includes a base, a plurality of buckle arms, and at least a first shape memory alloy wire coupled to a pair of the buckle arms. Another embodiment of the actuator includes a base and at least one bimorph actuator comprising a shape memory alloy material. The bimorph actuator is attached to the base.

[0004] In a first exemplary embodiment, a system is provided. In some examples, the system can include a camera actuation system having a first actuator comprising an autofocus actuator configured to actuate a lens in a z-direction and a second actuator comprising an optical image stabilization actuator configured to actuate the lens in either an x-direction or a y-direction. The system can include the first actuator comprising a first set of base portions and the second actuator comprising a second base portion.

[0005] The system may further include a set of wire springs. Each of the wire springs may include a first end connected to a corresponding portion of the first set of base portions of the first actuator. In some examples, the first end is welded to a corresponding portion of the first set of base portions of the first actuator. Each wire spring may also include a second end connected to a second base portion. In some examples, the second end is soldered to the second base portion. Each of the wire springs in the set may allow current to flow between the first actuator and the second actuator. Each of the wire springs may also include at least two flattened bends that generate a downward force to maintain each wire spring in a state aligned in the positive z-direction. In some examples, each of the wire springs in the set has a downward force of approximately 25 millinewtons.

[0006] In some examples, each of the sets of wire springs can include two angled bends. Further, each wire spring can include a substantially flat profile. In some examples, each of the sets of wire springs is configured to have a maximum profile of 0.2 mm in the positive z-direction in response to actuation of either the first actuator and / or the second actuator.

[0007] In another exemplary embodiment, wire springs are provided. The wire springs can include first ends configured to connect to corresponding portions of a first set of base portions of a first actuator. In some examples, the first ends are welded to corresponding portions of the first set of base portions of the first actuator. The wire springs can also include second ends configured to connect to second base portions of a second actuator. In some examples, the second ends are soldered to the second base portions. The wire springs can allow current to flow between the first actuator and the second actuator. The wire springs can also include at least two flattened bends that generate a downward force to maintain each wire spring aligned in the positive z-direction.

[0008] In some examples, the wire spring is part of a set of wire springs. Each of the set of wire springs can be configured to connect to a corresponding portion of the first set of base portions of the first actuator. In some examples, the wire spring comprises two angled bends, and the wire spring comprises a substantially flat profile. In some examples, the wire spring is configured to have a maximum profile of 0.2 mm in the positive z-direction in response to actuation of either the first actuator and / or the second actuator. In some examples, the wire spring comprises a downward force of approximately 25 millinewtons.

[0009] In another exemplary embodiment, a camera actuation system is provided. The camera actuation system can include an autofocus actuator having a first base portion set. The autofocus actuator can be configured to actuate a lens in a z-direction. The camera actuation system can also include an optical image stabilization actuator having a second base portion. The optical image stabilization actuator can be configured to actuate the lens in either an x-direction or a y-direction.

[0010] The camera actuation system can also include a set of wire springs, each of which can be connected at a first end to a corresponding portion of the first set of base portions of the autofocus actuator and at a second end to a corresponding portion of the second set of base portions.

[0011] In some examples, the set of wire springs includes a stainless steel material. Each of the set of wire springs can allow current to flow between the autofocus actuator and the optical image stabilization actuator. In some examples, each of the set of wire springs includes at least two flattened bends that generate a downward force to maintain each wire spring aligned in the positive z-direction. In some examples, each of the set of wire springs includes two angled bends, and each wire spring has a substantially flat profile. In some examples, a first end of each of the set of wire springs is welded to a corresponding portion of a first set of base portions of the first actuator, and a second end of each of the set of wire springs is soldered to a second base portion. In some examples, either the autofocus actuator and / or the optical image stabilization actuator includes a shape memory alloy (SMA) actuator including an SMA material configured to be actuated in response to current supplied to the SMA material.

[0012] Other features and advantages of embodiments of the present invention will be apparent from the accompanying drawings and from the detailed description that follows. Embodiments of the present invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, in which like reference symbols refer to similar elements and in which: [Brief explanation of the drawings]

[0013] [Figure 1A] 1 shows a prior art lens assembly including an SMA actuator configured as a buckle actuator. [Figure 1B] 1 shows a prior art SMA actuator. [Figure 2] 1 shows a prior art SMA actuator. [Figure 3] FIG. 1 shows an exploded view of a prior art autofocus assembly including an SMA actuator. [Figure 4] 1 shows a prior art autofocus assembly including an SMA actuator. [Figure 5] 1 shows a prior art SMA actuator including a sensor. [Figure 6] 1 illustrates an exploded view of an exemplary camera actuation system, according to an embodiment. [Figure 7] 1 illustrates a top view of an actuator comprising a set of wire springs engaged with an OIS actuator, according to an embodiment. [Figure 8] 1 illustrates a set of wire springs in a free-form state according to an embodiment. [Figure 9] 1 illustrates an exemplary flattened wire spring, according to an embodiment. [Figure 10] 10 illustrates a close-up view of a wire spring engaged with a base, according to an embodiment. [Figure 11A] 1 illustrates a side view of a wire spring before a preload force is applied, according to an embodiment. [Figure 11B] 1 illustrates a side view of a wire spring after a preload force has been applied, according to an embodiment. [Figure 12] 10 is a graph showing a comparison of arm profile and z-height for various wire springs according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Described herein are embodiments of SMA actuators that include a compact footprint while providing a high actuation height, e.g., movement in the positive z-axis direction (z-direction), referred to herein as z-stroke. Examples of SMA actuators include SMA buckle actuators and SMA bimorph actuators. SMA actuators can be used to mechanically impact two surfaces to produce the vibration sensation typically found in haptic feedback sensors and devices, as well as other systems in which actuators are used, in many applications, including, but not limited to, lens assemblies, microfluidic pumps, sensor shifters, optical image stabilization, optical zoom assemblies, as autofocus actuators, and other systems. For example, actuator embodiments described herein can be used as haptic feedback actuators for use in mobile phones or wearable devices configured to provide a user with an alarm, notification, alert, touched area, or button press response. Furthermore, two or more SMA actuators can be used in a system to achieve a larger stroke.

[0015] In various embodiments, the SMA actuator has a z-stroke greater than 0.4 millimeters. Additionally, various embodiments of the SMA actuator have a z-height of 2.2 millimeters or less when the SMA actuator is in its initial, unactuated position. Various embodiments of an SMA actuator configured as an autofocus actuator in a lens assembly may have a footprint as small as 3 millimeters larger than the lens inner diameter (“ID”). According to various embodiments, the SMA actuator may have a wider footprint in one direction to accommodate components including, but not limited to, sensors, wires, traces, and connectors. According to some embodiments, the footprint of the SMA actuator is 0.5 millimeters larger in one direction, e.g., the length of the SMA actuator is 0.5 millimeters larger than its width.

[0016] The embodiments described with respect to FIGS. 1A-5 represent prior art related to actuators as described in U.S. Pat. No. 10,920,755, the entire disclosure of which is incorporated herein by reference.

[0017] FIG. 1A illustrates a lens assembly including an SMA actuator configured as a buckle actuator according to one embodiment. FIG. 1B illustrates an SMA actuator configured as a buckle actuator according to one embodiment. Buckle actuators 102 are coupled to a base 101. As shown in FIG. 1B, SMA wires 100 are attached to the buckle actuators 102 such that when the SMA wires 100 are actuated and contract, the buckle actuators 102 buckle, causing at least a central portion 104 of each buckle actuator 102 to move in a z-stroke direction, e.g., the positive z-direction, as indicated by arrows 108. According to some embodiments, the SMA wires 100 are actuated when an electric current is supplied to one end of the wire through a wire retainer, such as a crimp structure 106. The electric current flows through the SMA wire 100, heating it due to the inherent resistance of the SMA material from which the SMA wires 100 are made. The other side of the SMA wire 100 has a wire retainer, such as a crimp structure 106, that connects the SMA wire 100 to ground and completes the circuit. Heating the SMA wire 100 to a sufficient temperature changes the inherent material properties from a martensitic to an austenitic crystalline structure, thereby changing the length of the wire. By varying the current, the temperature of the wire can be changed, and therefore the length of the wire, which is used to activate and deactivate the actuator, controlling the movement of the actuator in at least the Z direction. Those skilled in the art will understand that other techniques can be used to supply current to the SMA wire.

[0018] Figure 2 illustrates an SMA actuator configured as an SMA bimorph actuator according to one embodiment. As shown in Figure 2, the SMA actuator includes a bimorph actuator 202 coupled to a base 204. The bimorph actuator 202 includes an SMA ribbon 206. The bimorph actuator 202 is configured to move at least an unanchored end of the bimorph actuator 202 in a z-stroke direction 208 as the SMA ribbon 206 contracts.

[0019] FIG. 3 shows an exploded view of an autofocus assembly including an SMA actuator according to one embodiment. As shown, the SMA actuator 302 is configured as a buckle actuator 302 according to embodiments described herein. The autofocus assembly also includes an optical image stabilization ("OIS") actuator 304, a lens carriage 306 configured to hold one or more optical lenses using techniques including those known in the art, a return spring 308, a vertical plain bearing 310, and a guide cover 312. The lens carriage 306 is configured to slide relative to the vertical plain bearing 310 as the buckle actuator 302 moves in a z-stroke direction, e.g., the positive z-direction, when the SMA wire is actuated, pulling and deflecting the buckle actuator 302 using techniques such as those described herein. The return spring 308 is configured to apply a force to the lens carriage 306 in a direction opposite to the z-stroke direction, using techniques including those known in the art. According to various embodiments, the return spring 308 is configured to move the lens carriage 306 in the opposite direction of the z-stroke when the tension in the SMA wire decreases as the SMA wire is deactuated. When the tension in the SMA wire decreases to the initial value, the lens carriage 306 moves to its lowest height in the z-stroke direction. Figure 4 shows an autofocus assembly including an SMA wire actuator according to the embodiment shown in Figure 3.

[0020] FIG. 5 illustrates an SMA wire actuator according to one embodiment, including a sensor. In various embodiments, the sensor 502 is configured to measure the movement of the SMA actuator in the z-direction, or the movement of a component that the SMA actuator is moving, using techniques including those known in the art. The SMA actuator includes one or more buckle actuators 506 configured to be actuated using one or more SMA wires 508 similar to those described herein. For example, in the autofocus assembly described with reference to FIG. 4, the sensor is configured to determine the amount of movement that the lens carriage 306 moves in the z-direction 504 from an initial position, using techniques including those known in the art. According to some embodiments, the sensor is a tunnel magnetoresistive (TMR) sensor.

[0021] As described herein, the camera actuation system can include an autofocus (AF) actuator and / or an optical image stabilization (OIS) actuator. For example, the AF actuator can include one or more buckle actuators for moving the lens in the z-direction. Additionally, the OIS actuator can include one or more bimorph actuators for moving the lens in either the x- or y-direction. Any of the actuators described herein can include a shape memory alloy (SMA) material (e.g., a wire) configured to move a free end of the actuator in response to an electric current supplied to the SMA wire.

[0022] FIG. 6 shows an exploded view of an exemplary camera actuation system 600. As shown in FIG. 6, the system 600 can include an AF actuator 602 and an OIS actuator 604. The AF actuator 602 can include a base 606 having multiple electrically isolated portions. The portions of the base 606 can be formed or etched into sections from a single piece. The portions of the base 606 can include four isolated circuits for driving actuators (e.g., buckle actuators) within the AF actuator 602.

[0023] The OIS actuator 604 can include a base and one or more actuators (e.g., bimorph actuators). Additionally, the OIS actuator 604 can be configured to be actuated in both the x and y directions. The OIS actuator 604 can include multiple actuators, such as several bimorph actuators as part of a box actuator.

[0024] The system 600 can further include a set of wire springs 608. The wire springs 608 can be connected to both the AF actuator 602 and the OIS actuator 604. For example, the set of wire springs 608 can include wires 608a-d. Each of the set of wire springs 608a-d can be connected to a corresponding portion of the base 606 of the AF actuator 602. The springs 608a-d can provide electrical current between the AF actuator 602 and the OIS actuator 604.

[0025] In some examples, each wire spring 608a-d can include a first end (e.g., with a foot) having a connection welded to a section of the base 606 of the AF actuator 602. Additionally, each wire spring 608a-d can include a foot portion having a solder connection to a base portion (e.g., an OIS control flexible printed circuit (FPC)) of the OIS actuator 604.

[0026] The wire springs described herein can include 100 micrometers of stainless steel (gold-plated) material, which can provide an isolated electrical path for the closed-loop actuator in the AF actuator. The wire springs can further increase OIS centering stiffness while also subjecting the wire springs to lower stress during large x / y strokes during AF / OIS actuator actuation. This can improve reliability over other spring designs.

[0027] For example, in some cases, the spring may comprise a vertical wire (e.g., a strut spring) that electrically connects the camera base and the AF actuator. However, such springs may flex during actuator actuation, potentially making the spring susceptible to increased stress and reduced reliability. For example, a strut spring may include a resilience of approximately 300k cycles at a stroke (x / y) of ±250 micrometers (μm). In contrast, the wire springs described herein can withstand an infinite amount of cycles at a stroke (x / y) of ±330 μm. Thus, the wire springs described herein may have greater resilience than other spring designs.

[0028] Additionally, the wire springs described herein can provide a downward force against the bearing to achieve near-zero dynamic tilt effect. By flattening the wire bends of the wire springs, a downward force (e.g., about 25 millinewtons) can be provided while occupying only about 0.2 mm of z-space within the camera assembly. This can minimize the impact on the required height of the camera assembly.

[0029] 7 shows a top view of an actuator 700 comprising a set of wire springs engaged with an OIS actuator. Although four wire springs 708a-d are shown, the embodiments described herein are not limited to such example and any number of wire springs can be arranged in the systems described herein.

[0030] Each wire spring 708a-d can be disposed within an OIS actuator. Furthermore, the maximum stroke movement of the OIS actuator can be approximately ±330 μm (x / y). The maximum stress on a flat wire spring can be approximately 423 megapascals (Mpa). Such stress on the wire spring can be below the infinite fatigue stress limit, indicating minimal or no fatigue on the wire spring during multiple actuation cycles. For example, a wire spring can have a maximum stress of 423 Mpa, but the infinite fatigue limit can be 1276 Mpa / 2 = approximately 638 Mpa.

[0031] Figure 8 shows a set of wire springs 808a-d in a freely formed state. As shown in Figure 8, a second end 812a-d of each wire spring 808a-d can be connected to a base portion 806. The base portion 806 can include the base of an OIS actuator described herein.

[0032] Additionally, each wire spring 808a-d can include a first end with a foot portion 810a-d. The first end 810a-d of each wire spring 808a-d can be configured to be attached (welded, soldered) to a base portion of an AF actuator.

[0033] The embodiment of FIG. 8 shows a wire spring in a free-form state, which can include a state in which a tool can clamp the central flat plate section (806 and 812a-d), another clamp can hold the four outer pads or feet (810a-d), and the two clamps can then move 6.4 mm relative to each other in the Z direction. The spring arms can then plastically deform at higher stress locations along their length based on the spring design. The springs can then spring back a certain amount in the Z direction, appearing, for example, as depicted in FIG. 11A. Furthermore, a precision bending mold can clamp the top and bottom of the material and then push the material up near the clamps to localize the plastic deformation of the material between the clamps and the indentation tool to a precise, defined location. In some examples, a flattened bend (e.g., as shown in FIG. 9) can be placed before applying the free-form preload as described with reference to FIG. 8.

[0034] A preload force can be applied to each of the wire springs. The preload force can apply a downward force to each of the wire springs to prevent movement of the wire springs in the negative z-direction. For example, the wire springs can be free-formed by 6.4 mm to create the preload. Higher preload forces can have higher arm deflections. For example, a preload of 25 mN can include a total Z-deflection of approximately 0.5 mm. Additionally, flattening bends can be added to the wire springs before free-forming, which can further reduce the arm deflection to 0.1 mm (or an overall height of 0.2 mm).

[0035] Figure 9 shows an exemplary flattened wire spring 908. As shown in Figure 9, the wire spring 908 can be flattened so that it is substantially flat with the base 906. The wire spring 908 can provide a downward force of approximately 25 millinewtons.

[0036] 9, wire spring 908 can include a first end 910 and a second end 912. Wire spring 908 can include flattened bends 914a-b. Flattened bends 914a-b can each include a first bend 914a having an angle of +3.5 degrees and a second bend 914b having an angle of −3.5 degrees. Wire spring 908 can also include angled bend portions 916a-b. Angled bend portions 916a-b can include rounded corners to provide wire spring 908 with an approximately 180-degree bend.

[0037] FIG. 12 is a graph 1200 illustrating a comparison of arm profile and z-height for various wire springs. For example, graph 1200 may include an x-axis indicating arm profile length (mm) and a y-axis indicating z-height (mm). As shown in FIG. 12, a first trend line 1202 may represent the behavior of the wire springs that were only free-formed. The first trend line 1202 represents the z-height of the wire springs that were only free-formed, which may be, for example, +0.3 mm to -0.2 mm.

[0038] Additionally, a second trend line 1204 can represent the flattened wire spring embodiment described herein. The second trend line 1204 can indicate that the maximum z-height of the wire spring can be approximately +0.2 mm, and that the z-height of the wire spring is never negative. A preload force on the wire spring can result in the wire spring not being deflected in the negative z-direction. This design can eliminate the need for foot clearance in the camera apparatus, which can affect the overall height of the camera apparatus design.

[0039] In some embodiments, the system can include four spring arms for the OIS actuator. This can provide symmetry and provide four electrical circuits for powering the closed-loop AF actuator attached to the flat OIS spring. The stiffness in the x and y directions can be 100-150 N / m. This can provide centering stiffness to the OIS without affecting the x / y stroke, while also adjusting the width and length of the spring arms.

[0040] FIG. 10 shows a close-up view of the wire spring engaged with the base. As shown in FIG. 10, the wire spring 1002 can include a width 1004 and a thickness 1006. The width 1004 can be in the range of 90 to 140 micrometers (μm), and the overall arm length can be in the range of 24 to 26 millimeters (mm). Furthermore, the z-preload force can be between 15 and 35 mN. The preload force can ensure that the OIS does not lift off the planar bearing due to gravity; otherwise, the lens may not be flat against the image sensor, blurring the image captured by the image sensor. Furthermore, the thickness 1006 can be between 0.1 mm and 0.15 mm. A thickness beyond this range can adversely affect the X / Y stiffness, as the system may not obtain sufficient Z stiffness to achieve the Z-preload force. This can increase the need to form the spring arms upward so that they can be further depressed and welded / soldered / glued for the additional preload force.

[0041] 11A-11B show side views of a wire spring before and after a preload force is applied. For example, as shown in FIG. 11A, system 11A00 can include a foot portion 11A02 and a second end 11A04 attached to a base. Before the preload force, spring height 11A06 can exist between foot portion 11A02 and second end 11A04. After the preload force is applied, the overall height of the spring can be less than 0.25 mm.

[0042] Additionally, the wire spring can include one or more flattening bends and loops. The flattening bends can be located near the beginning of each spring arm loop. The first loop can be formed downward between 1 and 6 degrees to reduce the final positive height of the section of the spring arm. Additionally, the second loop can be formed upward between 1 and 6 degrees to reduce the final negative height of the section of the spring arm.

[0043] The preload form can include spring arms that are pulled upward to a set height and then released, allowing the spring arms to rebound to a deformation height. The preload form height can be between 5 and 9 mm. The foot and center section of each spring arm can be parallel during the molding process.

[0044] The bounce height can range from 0.6 to 2 mm. The spring foot can be deformed and bounced to a positive height about the center section. The spring arm foot can then be pressed down onto a lower base, which can then be welded, soldered, or glued to secure the spring arm foot for operation. The flattened bend can reduce the overall Z height of the spring arm by more than a factor of two. For example, in FIG. 11B, a preload force 11B06 can be applied to the spring.

[0045] In a first exemplary embodiment, a system is provided. In some examples, the system can include a camera actuation system (e.g., 600) having a first actuator comprising an autofocus actuator (e.g., 602) configured to actuate a lens in the z-direction and a second actuator (e.g., 604) comprising an optical image stabilization actuator configured to actuate the lens in either the x- or y-direction. The system can include the first actuator (e.g., 602) comprising a first set of base portions (e.g., 606) and the second actuator (e.g., 604) comprising a second base portion (e.g., 806).

[0046] The system may further include a set of wire springs (e.g., 108a-d, 808a-d). Each of the wire springs may include a first end (e.g., 810a-d) connected to a corresponding portion of the set of first base portions (e.g., 106) of the first actuator. In some examples, the first end is welded to a corresponding portion of the set of first base portions of the first actuator. Each wire spring may also include a second end (e.g., 812a-d) connected to a second base portion. In some examples, the second end is soldered to the second base portion. Each of the wire springs in the set may allow current to flow between the first actuator and the second actuator. Each of the wire springs may also include at least two flattened bends (e.g., 914a-b) that generate a downward force to maintain each wire spring in a state aligned in the positive z-direction. In some examples, each of the wire springs in the set has a downward force of approximately 75 millinewtons.

[0047] In some examples, each of the set of wire springs can include two angled bends (e.g., 916a-b). Further, each wire spring can include a substantially flat profile (e.g., a profile substantially similar to the profile of an OIS actuator). In some examples, each of the set of wire springs is configured to have a maximum profile of 0.2 mm in the positive z-direction in response to actuation of either the first actuator and / or the second actuator.

[0048] In another exemplary embodiment, wire springs are provided. The wire springs can include first ends configured to connect to corresponding portions of a first set of base portions of a first actuator. In some examples, the first ends are welded to corresponding portions of the first set of base portions of the first actuator. The wire springs can also include second ends configured to connect to second base portions of a second actuator. In some examples, the second ends are soldered to the second base portions. The wire springs can allow current to flow between the first actuator and the second actuator. The wire springs can also include at least two flattened bends that generate a downward force to maintain each wire spring aligned in the positive z-direction.

[0049] In some examples, the wire spring is part of a set of wire springs. Each of the set of wire springs can be configured to connect to a corresponding portion of the first set of base portions of the first actuator. In some examples, the wire spring comprises two angled bends, and the wire spring comprises a substantially flat profile. In some examples, the wire spring is configured to have a maximum profile of 0.2 mm in the positive z-direction in response to actuation of either the first actuator and / or the second actuator. In some examples, the wire spring comprises a downward force of approximately 25 millinewtons.

[0050] In another exemplary embodiment, a camera actuation system is provided. The camera actuation system can include an autofocus actuator having a first base portion set. The autofocus actuator can be configured to actuate a lens in a z-direction. The camera actuation system can also include an optical image stabilization actuator having a second base portion. The optical image stabilization actuator can be configured to actuate the lens in either an x-direction or a y-direction.

[0051] The camera actuation system can also include a set of wire springs, each of which can be connected at a first end to a corresponding portion of the first set of base portions of the autofocus actuator and at a second end to a corresponding portion of the second set of base portions.

[0052] In some examples, the set of wire springs includes a stainless steel material. Each of the set of wire springs can allow current to flow between the autofocus actuator and the optical image stabilization actuator. In some examples, each of the set of wire springs includes at least two flattened bends that generate a downward force to maintain each wire spring aligned in the positive z-direction. In some examples, each of the set of wire springs includes two angled bends, and each wire spring has a substantially flat profile. In some examples, a first end of each of the set of wire springs is welded to a corresponding portion of a first set of base portions of the first actuator, and a second end of each of the set of wire springs is soldered to a second base portion. In some examples, either the autofocus actuator and / or the optical image stabilization actuator includes a shape memory alloy (SMA) actuator including an SMA material configured to be actuated in response to current supplied to the SMA material.

[0053] It will be understood that terms such as "top," "bottom," "upper," "lower," and x-, y-, and z-directions used herein are used as terms of convenience to indicate the spatial relationship of parts to one another, rather than any particular spatial or gravitational orientation. These terms are therefore intended to encompass an assembly of component parts, whether the assembly is oriented in the particular orientation shown in the drawings and described herein, or whether it is oriented upside down from that orientation, or any other rotational variation thereof.

[0054] It should be understood that the term "the present invention," as used herein, should not be interpreted to mean that only a single invention having a single essential element or group of elements is presented. Likewise, it should be understood that the term "the present invention" encompasses several separate innovations, each of which can be considered a separate invention. While the present invention has been described in detail with reference to preferred embodiments and drawings thereof, it should be apparent to those skilled in the art that various adaptations and modifications of the embodiments of the present invention can be made without departing from the spirit and scope of the present invention. In addition, the techniques described herein can be used to create devices having two, three, four, five, six, or more generally, n bimorph and buckle actuators. It should therefore be understood that the above detailed description and accompanying drawings are not intended to limit the scope of the present invention, which should be inferred solely from the following claims and their appropriately interpreted legal equivalents.

Claims

1. a first actuator having a first set of base portions; a second actuator having a second base portion; a set of wire springs; Each of the sets of wire springs comprises: a first end connected to a corresponding portion of the first set of base portions of the first actuator; a second end connected to the second base portion, each of the sets of wire springs allowing current to flow between the first actuator and the second actuator; at least two flattening flexures for maintaining each wire spring aligned in a positive z-direction, the set of wire springs including a preload for creating a downward force on the set of wire springs; A system comprising:

2. the system comprises a camera actuation system; The camera operation system includes: the first actuator comprising an autofocus actuator configured to actuate a lens in the z-direction; the second actuator comprising an optical image stabilization actuator configured to actuate the lens in either an x-direction or a y-direction; The system of claim 1 , comprising:

3. The system of claim 1 , wherein each of the set of wire springs comprises two angled bends, and each wire spring comprises a substantially flat profile.

4. The system of claim 1 , wherein the first ends are welded to corresponding portions of the first set of base portions of the first actuator.

5. The system of claim 1 , wherein the second end is soldered to the second base portion.

6. 2. The system of claim 1, wherein each of the sets of wire springs is configured to have a maximum profile in the positive z-direction of about 0.2 mm in response to actuation of either the first actuator and / or the second actuator.

7. 10. The system of claim 1, wherein each of the sets of wire springs provides a downward force of approximately 25 millinewtons.

8. A wire spring, a first end configured to connect to a corresponding portion of a first set of base portions of a first actuator; a second end configured to connect to a second base portion of a second actuator, the wire spring allowing current to flow between the first actuator and the second actuator; at least two flattened flexures for maintaining each wire spring disposed in a positive z-direction, the wire springs including a preload for creating a downward force on the wire springs; A wire spring comprising:

9. 9. The wire spring of claim 8, wherein the wire spring is part of a set of wire springs, each of the set of wire springs configured to connect to a corresponding portion of the first set of base portions of the first actuator.

10. The wire spring of claim 8 , wherein the wire spring comprises two angled bends, and the wire spring comprises a substantially flat profile.

11. The wire spring of claim 8 , wherein the first ends are welded to corresponding portions of the first set of base portions of the first actuator.

12. The wire spring of claim 8 , wherein the second end is soldered to the second base portion.

13. 9. The wire spring of claim 8, wherein the wire spring is configured to have a maximum profile in the positive z direction of about 0.2 mm in response to actuation of either the first actuator and / or the second actuator.

14. 9. The wire spring of claim 8, wherein the wire spring comprises a downward force of approximately 25 millinewtons.

15. an autofocus actuator comprising a first set of base portions, the autofocus actuator configured to actuate a lens in a z-direction; an optical image stabilization actuator comprising a second base portion, the optical image stabilization actuator configured to actuate the lens in either an x-direction or a y-direction; a set of wire springs, each of the set of wire springs connected at a first end to a corresponding portion of the first set of base portions of the autofocus actuator and connected at a second end to the second set of base portions; A camera actuation system comprising:

16. 16. The camera actuation system of claim 15, wherein the set of wire springs comprises a stainless steel material, and each of the set of wire springs allows electrical current to flow between the autofocus actuator and the optical image stabilization actuator.

17. 16. The camera actuation system of claim 15, wherein each of the sets of wire springs includes at least two flattened bends to maintain each wire spring aligned in the positive z direction.

18. 16. The camera actuation system of claim 15, wherein either the autofocus actuator and / or the optical image stabilization actuator comprises a shape memory alloy (SMA) actuator, the shape memory alloy (SMA) actuator including SMA material configured to be actuated in response to an applied electrical current.

19. 16. The camera actuation system of claim 15, wherein each of the set of wire springs comprises two angled bends, and each wire spring comprises a substantially flat profile.

20. 16. The camera actuation system of claim 15, wherein the first end of each of the set of wire springs is welded to a corresponding portion of the first set of base portion of the first actuator, and the second end of each of the set of wire springs is soldered to the second base portion.

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