Shape memory alloy actuator

Abstract

The present technology generally relates to shape memory alloy actuators, and to methods of making such SMA actuators. We describe a shape memory alloy (SMA) actuator comprising: a static element (104); a movable element (106) movable relative to the static element; and a plurality of SMA wires (108) each connected to one or both of the static element and the movable element and causing movement of the movable element when contracted. At least one connector (110a, 110c), preferably a crimp connector, connects at least two of the plurality of SMA wires (108) to at least one of the static element and the movable element.

Description

[0001] The present technology generally relates to shape memory alloy actuators, and to methods of making such SMA actuators.

[0002] Consumer electronic devices such as laptops and smartphones may employ different types of controls to provide some feedback to the user of the device indicating that they have successfully pressed a button on the device. This is often referred to as tactile feedback, and a tactile button or control on a device may provide a tactile sensation to the user to confirm that they have successfully pressed the button / control / switch. In order to generate a good tactile sensation, it is desirable that the actuator moves with a high enough force to provide sufficient displacement. It should be understood that there are other applications, such as latches or medical devices, where high forces are also required to achieve relatively large displacements.

[0003] The applicants have identified a need for improved shape memory alloy actuators.

[0004] According to a first method of the present technology, a shape memory alloy (SMA) actuator is provided, which includes a static element; a movable element that is movable relative to the static element; a plurality of SMA wires, each of which is connected to one or both of the static element and the movable element and causes movement of the movable element when contracted; and a connecting element that connects at least two wires from the plurality of SMA wires to one of the static element and the movable element.

[0005] Preferably, the coupling element comprises a crimp connector holding at least two wires.

[0006] According to a second method of the present technology, a tactile component is provided, which includes a touchable part (such as a button) and the above-mentioned actuator, wherein when the user presses or releases the touchable part, the actuator component is activated to provide tactile feedback to the user by moving the touchable part using a movable element.

[0007] According to another method of the present technology, a method of making an SMA actuator (eg, one as described above) is provided, the method comprising: feeding a plurality of SMA wires into an open crimp connector; closing the crimp connector; and trimming any excess wire.

[0008] According to another method of the present technology, there is provided an apparatus comprising any of the SMA actuators described herein. The apparatus may be a smartphone, a camera, a foldable smartphone, a foldable image capture device, a foldable smartphone camera, a foldable consumer electronic device, a camera with folded optics, an image capture device, an array camera, a 3D sensing device or system, a servo motor, a consumer electronic device (including household appliances such as vacuum cleaners, washing machines, and lawn mowers), a mobile or portable computing device, a mobile or portable electronic device, a laptop computer, a tablet computing device, an e-reader (also known as an e-book reader or e-book device), a computing accessory or computing peripheral device (e.g., a mouse, keyboard, headphones, earphones, earbuds, etc.), an audio device (e.g., a headset, a head-mounted The invention also includes devices such as a headset, a headset, a headphone, an earphone, etc., a security system, a gaming system, a gaming accessory (e.g., a controller, a headset, a wearable controller, a joystick, etc.), a robot or robotic device, a medical device (e.g., an endoscope), an augmented reality system, an augmented reality device, a virtual reality system, a virtual reality device, a wearable device (e.g., a watch, a smart watch, a fitness tracker, etc.), an autonomous vehicle (e.g., a driverless car), a vehicle, a tool, a surgical tool, a remote control (e.g., for a drone or a consumer electronic device), an apparel (e.g., a dress, a shoe, etc.), a switch, a dial, or a button (e.g., a light switch, a thermostat dial, etc.), a display screen, a touch screen, and a near field communication (NFC) device. It should be understood that this is a non-exhaustive list of possible devices.

[0009] Preferred features are set out in the attached dependent claims.

[0010] Embodiments of the present technology will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0011] Figure 1a is a schematic cross-sectional view of a first haptic component;

[0012] Figure 1b is a schematic cross-sectional view of a second haptic assembly;

[0013] Figure 1c yes Figure 1b Schematic enlargement of the interior details;

[0014] Figure 2a and Figure 2b yes Figure 1a to Figure 1c a schematic block diagram of the functional arrangement of the haptic components shown;

[0015] Figure 3ais a graph plotting the temperature of each of the following wires as a function of time for a single wire having a diameter of 60 μm that is heated, for each of the middle wire (W2) and the outer wire (W1) in a set of three adjacent contacting wires (each having a diameter of 35 μm and heated), and for each of the middle wire (W2) and the outer wire (W1) in a set of three wires (each having a diameter of 35 μm that are heated but spaced such that the wires are adjacent but not in contact);

[0016] Figure 3b When drawn Figure 3a The arrangement of the lines is a graph of temperature variation with time when cooling;

[0017] Figure 4a is similar to Figure 1b A schematic cross-sectional view of another haptic assembly is shown;

[0018] Figure 4b is a graph plotting temperature versus time for various distances between the heat sink and the wire (e.g., 420 μm to 40 μm) as the wire is cooled;

[0019] Figure 4c is a graph that plots the temperature versus the distance between the heat sink and the wire as the wire is cooled, where the temperature is the value after cooling for 100 milliseconds or 200 milliseconds, respectively;

[0020] Figure 4d is a graph plotting temperature versus time for various distances between the heat sink and the wire (e.g., 420 μm to 40 μm) as the wire is heated;

[0021] Figure 5 is a graph plotting the time variations of the different displacements used to restore each of the three different arrangements;

[0022] Figure 6a and Figure 6b are schematic partial views of different arrangements of crimps used in assemblies;

[0023] Figure 7 is a schematic cross-sectional view of a third haptic assembly; and

[0024] Figure 8 is a schematic diagram of the method of crimping wires in an SMA actuator.

[0025] The embodiments described below illustrate shape memory alloy (SMA) actuators. Such SMA actuators may be any type of device that includes a static part (or element - these words are used interchangeably) and a movable part that is movable relative to the static part. The movable part is moved by a plurality of SMA wires that are coupled (or connected - these words are used interchangeably) between the static part and the movable part. A coupling element couples at least two wires to at least one of the static part and the movable part. The coupling element may couple any number (N) of wires, and by way of example only, between two and six wires.

[0026] The coupling element may provide a direct connection between the at least two SMA wires and one of the static element and the movable element. In an arrangement with a direct connection at both ends of the SMA wires, "coupled between" means that there are only SMA wires and coupling elements between the static element and the movable element. Optionally, the coupling element may couple the at least two wires to an intermediate component to provide an indirect connection between the at least two wires and one of the static element and the movable element. The intermediate element itself may be connected to one of the static element and the movable element by a direct connection or an indirect connection. For an indirect connection, the intermediate element itself may be connected to at least one other intermediate element, and for a direct connection, the intermediate element is directly connected to one of the static element and the movable element.

[0027] The coupling element may include a fixed connector that provides a permanent (i.e., fixed) connection between the SMA wire and the static element or the movable element. Such a fixed connector may be in the form of a crimping connector, a welding component welded to at least two wires to form a welding point, or other similar connectors. When a crimping connector is used, the coupling element may include a single crimping connector that holds multiple wires, or may include multiple adjacent crimping connectors, each of which holds a single wire. The crimping connector or each crimping connector may have a width between 500 μm and 750 μm. Adjacent crimping connectors may be vertically aligned, i.e., may be stacked. Optionally, adjacent crimping connectors may be laterally offset from each other, or vertically offset from each other, or laterally and vertically offset from each other.

[0028] The coupling element may optionally include a connector that provides a non-fixed connection between the plurality of SMA wires and the static element or the movable element. Such a non-fixed connector may be in the form of a protruding element, such as a hook, dowel pin, or similar element, around which the SMA wires are looped or similarly held in place.

[0029] There may be a first coupling element coupling one end of the SMA wire to the static element, and a second coupling element coupling the opposite end of the SMA wire to the movable element. The first coupling element may be of the same type as the second coupling element, i.e. both the first coupling element and the second coupling element may be crimp connectors that hold multiple wires or may be welded points, the crimp connectors may include multiple adjacent crimp connectors, each of which holds a single wire. Alternatively, the first coupling element may be of a different type than the second coupling element, i.e. the first coupling element may include one or more crimp connectors, and the second coupling element may be a protruding element, or the first coupling element may be a crimp connector that holds multiple wires, and the second coupling element may include multiple adjacent crimp connectors (each of which holds a single wire).

[0030] A first coupling element and a second coupling element coupled to the same wire may be considered to form a pair of coupling elements. There may be multiple pairs of first coupling elements and second coupling elements, wherein each pair of coupling elements couples at least two different wires to both the static element and the movable element. In this way, multiple wires may be divided between pairs of coupling elements. For example, there may be six wires, wherein a first group of three wires are coupled between a first pair of coupling elements, and a second group of three wires are coupled between a second pair of coupling elements.

[0031] When multiple wires are activated, such as in a haptic assembly, in response to detecting a need for tactile feedback, the SMA wires contract, thereby moving the movable part. A first pair of coupling elements may couple a first group of at least two wires to the movable element, and a second pair of coupling elements may couple a second group of at least two wires to the movable element, wherein when the wires coupled to the first pair of coupling elements and the second pair of coupling elements contract, the movable element moves in one direction. For example, a first pair of coupling elements may couple at least two wires to one side of the movable element, and a second pair of coupling elements may couple at least two wires to the opposite side of the movable element, and the direction of movement may be substantially parallel to the opposite side of the movable element. Arranging the paired coupling elements on the opposite sides of the movable element may result in a balanced application of the force from the contraction of the wires, i.e., rotation of the movable element may be avoided. Similar results may be obtained by coupling at a position close to the opposite edge of one end of the movable element. These are merely examples, and any suitable coupling position on the movable element may be used.

[0032] The movable part can be restored to its original position by a restoring element that provides a restoring force. When the activation of the SMA wire stops, such as power failure, the SMA wire can also be restored to its original length by the restoring element. The restoring element can be an elastic element, such as a spring, a flexure, other SMA wires, or a force applied by a user's finger to the surface of the touchable part. For example, there may be a first pair of coupling elements that connect the first group of at least two wires to the movable element and a second pair of coupling elements that connect the second group of at least two wires to the movable element, wherein when the first group of at least two wires are contracted, the movable element moves in a first direction, and when the second group of at least two wires are contracted, the movable element moves in a direction opposite to the first direction. For example, a first pair of coupling elements can connect the first group of at least two wires to one end of the movable element, and a second pair of coupling elements can connect the second group of at least two wires to the opposite end of the movable element. This is just an example, and any suitable coupling position on the movable element can be used.

[0033] Embodiments of the present technology describe SMA actuators designed to transmit high forces, such as between 1.2 and 3N, more preferably between 1.2 and 10N, while maintaining the strain in the wire within safe limits (e.g., a 2%-3% reduction in length from the original length). The force will depend on the desired target displacement. Multiple relatively thin wires (e.g., such as approximately 25μm or 35μm in diameter) are used in combination to provide the desired force. As explained in more detail below, the use of multiple wires provides a total cross-section designed to transmit the desired force. In addition, the use of multiple wires allows the wire to cool faster than a single wire of similar cross-section. Therefore, multiple thinner SMA wires are ready to be reactivated faster than a single wire of equivalent cross-sectional area.

[0034] SMA actuators may be incorporated into tactile assemblies to move a button or other touchable element (movable element) contacted by a user relative to a housing or shell (static element), thereby delivering a tactile perception to a user pressing the button (or other touchable element). Embodiments of the present technology describe a tactile assembly that may be arranged to move a button laterally along an edge of a device, perpendicular to the edge of the device, spirally around an axis perpendicular to the edge of the device, or in any other suitable direction, such as rotating in a plane parallel to the edge of the device or in a plane perpendicular to the device. Examples of actuators that move a button in a lateral direction relative to a user's contact are described, for example, in WO2018 / 046937 and GB2551657. Examples of actuators that produce vertical movement are described in GB1803084.1 and GB1813008.8 of the present applicant. Examples of arrangements of crimps that may be used to connect an SMA actuator to a haptic assembly are described in WO2016 / 189314, GB1800484.6, GB1801291.4 and GB1815673.7.

[0035] The present technology can provide localized tactile sensations caused by direct impulses rather than through inertial effects. For example, a smartphone includes an inertial tactile actuator - a relatively large mass is moved when a tactile effect is desired. The movement of this mass causes the entire smartphone to shake or vibrate. Therefore, the tactile effect is global rather than localized. The present technology provides localized tactile feedback. In addition, the tactile feedback provided by the present technology can be customized by the user by modifying software parameters. This allows different types of tactile feedback to be provided for different purposes or to suit different users.

[0036] Each haptic component described herein may be incorporated into any device in which providing tactile feedback to a user of the device may be useful. For example, the haptic component may be incorporated into any electronic device or consumer electronic device previously listed, including but not limited to computers, laptops, portable computing devices, smartphones, computer keyboards, gaming systems, portable gaming devices, gaming equipment / accessories (e.g., controllers, wearable controllers, etc.), medical devices, user input devices, and the like. It should be understood that this is a non-limiting, non-exhaustive list of possible devices that may incorporate any of the haptic components described herein. For example, the haptic components described herein may be incorporated into a smartphone or otherwise provided along the edge of a smartphone or on the surface of a smartphone.

[0037] Various SMA actuators are now described with reference to the accompanying drawings. It should be understood that elements or features described with respect to a particular drawing may be equally applicable to any drawing described herein, for example, a crimp that holds multiple wires may be used in conjunction with a crimp that holds a single wire, the total number of SMA wires may be selected to provide the desired force, and a heat sink (one or more) may be incorporated in any embodiment. In addition, while the drawings show the SMA actuator being incorporated into a haptic assembly, it should be understood that the SMA actuator may be incorporated into other devices that require high forces, such as latches or medical devices.

[0038] Figure 1a A cross-sectional view of a first arrangement of SMA actuators within a haptic assembly 100 is shown. The haptic assembly 100 includes a button 102 (although it should be understood that other touchable components, surfaces, or elements may be used interchangeably). A user may press the button 102 to perform a particular operation, such as making a selection, opening / closing a device, entering data (e.g., typing on a keyboard), scrolling, opening / closing a function of the device in which the assembly 100 resides, or adjusting that function (e.g., adjusting the volume of audio output from the device), etc. Pressing or releasing the button 102 may result in haptic feedback or conveying a haptic sensation to the user, thereby providing the user with some sensory feedback (particularly touch-based feedback) to indicate that the operation has been performed.

[0039] In many of the arrangements described herein, the button 102 may be a surface feature on a device / apparatus containing a tactile component. Such a surface may be pressed in a manner similar to a button, and pressing or releasing the surface may be detected by a sensor and may trigger tactile feedback. However, instead of pressing or releasing a button (or surface) to trigger tactile feedback, tactile feedback may be triggered by software in response to another event. For example, if a user makes a selection on the screen of their smartphone, the selection may cause tactile feedback to be triggered, wherein feedback is provided by a button or surface feature. (Software-triggered tactile feedback may occur in a specific application, such as in a game and / or virtual / augmented reality device). Therefore, in many of the arrangements and embodiments described herein, in order to deliver tactile feedback, it may not be necessary to directly press the tactile button 102. However, in each case, the mechanism will determine which sensor has recorded the need to provide tactile feedback, and in the case where there are multiple actuators to provide feedback, the mechanism can determine which (which) appropriate actuators will be activated to provide tactile feedback.

[0040] exist Figure 1aIn the arrangement shown, the haptic assembly 100 may include a housing 104 (also referred to herein as a "support," "chassis," "box," and "housing"). The housing 104 may include a cavity or recess. The button 102 may be disposed within the cavity of the housing 104. As shown, the button may be arranged with the cavity so that a contact surface (also referred to as an exterior surface, outer surface, or upper surface) of the button is substantially level / flush with the exterior surface of the housing 104. Alternatively, the button may protrude from the housing. It should be understood that the housing 104 surrounds and encloses the button 102 so that only the contact surface 106 of the button is visible / touchable to a user.

[0041] The SMA actuator may include an intermediate movable element 106 disposed within a cavity below the button 102. The movable element 106 is movable relative to the static part (i.e., the housing) in a first direction perpendicular to the outer surface of the housing 104. The user's finger is moved on the button of Contact on the contact surface may cause the button to move into or out of the housing, as appropriate, such as in the direction of arrow 116. A sensor (not shown) may be mounted in the housing below the button 102 and the movable element 106. The sensor is any suitable sensor for determining that tactile feedback is required, such as by detecting the pressing of a button. The sensor may be coupled to a control circuit (not shown), and the sensor may be configured to communicate with the control circuit when tactile feedback is required. For example, the sensor may detect when the force acting on the sensor changes, or when the force acting on the sensor has been applied for a minimum duration. As an example, the sensor's detection of a user pressing a button causes tactile feedback to be generated and applied by the tactile component.

[0042] The movable element 106 can also be moved relative to the housing in a different second direction, which can be substantially perpendicular to the first direction, such as substantially parallel to the outer surface of the housing 102. Movement of the movable element 106 in the second direction can cause movement of the button 102 in the first direction to provide a tactile sensation to the user. The concept of moving the intermediate movable element 106 in one direction to cause movement of the button 102 in another direction can be implemented in a variety of ways.

[0043] There are a plurality of bearings 128 between the inclined sides of the movable element 106 and the adjacent inclined sides of the button to reduce friction between the movable element and the button. Similarly, there are a plurality of bearings between the movable element 106 and the housing to facilitate movement of the movable element by reducing friction.

[0044] The term "bearing" is used interchangeably herein with the terms "sliding bearing", "plain bearing", "rolling bearing", "ball bearing", "flexure", and "roller bearing". The term "bearing" as used herein generally means any element or combination of elements whose function is to limit motion to only desired motion and reduce friction between moving parts. The term "plain bearing" is used to mean a bearing in which a bearing element slides on a bearing surface, and includes "plain bearings". The term "rolling bearing" is used to mean a bearing in which a rolling bearing element (e.g., a ball or roller) rolls on a bearing surface. The bearing may be disposed on or may include a nonlinear bearing surface. In some embodiments of the present technology, more than one type of bearing element may be used in combination to provide bearing functionality. Therefore, the term "bearing" as used herein includes, for example, any combination of plain bearings, ball bearings, roller bearings, and flexures. In embodiments, a suspension system may be used to suspend an intermediate movable element and / or a button within a tactile assembly and limit motion to only desired motion. For example, a suspension system of the type described in WO2011 / 104518 may be used. It should therefore be understood that the term "bearing" as used herein also means "suspension system". In embodiments, the bearing may be arranged on or may include a non-linear bearing surface. The bearing may be formed of any suitable material, such as ceramic.

[0045] In this arrangement, the button 102 and the movable element 106 are wedge-shaped, so that the wider end of the wedge-shaped button 102 is adjacent to the narrower end of the wedge-shaped movable element 106. This arrangement means that the button is moved in a first direction (i.e., generally perpendicular to the surface of the housing) when the movable element 106 is moved in a second direction (i.e., generally parallel to the surface of the housing) within the housing 104. In this arrangement, the intermediate movable element 110 is a "single wedge" in that only one surface of the element is inclined / beveled.

[0046] The SMA actuator includes a plurality of (e.g., N) shape memory alloy (SMA) actuator wires 108, for example, there may be 2 to 6 wires. As shown, the SMA wires 108 extend into another cavity 112 in the housing 104. Both ends of the SMA actuator wires 108 are connected to the housing 104 using a pair of coupling elements in the form of connectors / crimps 110a, 110b, which are electrical connectors and mechanical connectors (for connecting the SMA actuator wires to a power source). Each connector holds the ends of the plurality of wires. Each of the SMA wires 108 is hooked at its midpoint on a hook 120 disposed on one side of the movable element 106. Therefore, the hook is another coupling element that couples and connects the plurality of SMA wires to the movable element. Each half of each wire can be considered to form an effective wire segment, and the two effective wire segments of each SMA actuator wire act mechanically in parallel, and therefore, each looped SMA actuator wire can provide twice the force of a single wire (which only crosses once from the movable element to the housing).

[0047] In this arrangement, there is one coupling element that couples each SMA wire to the movable element at its midpoint using a hook, and there are two further coupling elements in the form of crimps, each of which couples the plurality of SMA wires to the static element at one end thereof. Thus, the coupling element that couples each SMA wire to the movable element has a different structure (i.e., is of a different type) than the coupling element that couples each SMA wire to the static element. Furthermore, in this arrangement, the crimp is between each SMA wire and the static element, so each SMA wire has a direct connection to the static element, but it should be understood that the connection may also be indirect, so there may be one or more intermediate elements between each SMA wire and the static element.

[0048] When tactile sensation is desired, the requirement is communicated to the control circuit (not shown). Each SMA actuator wire 108 is then powered. When each SMA actuator wire 108 is powered, it heats up and contracts. The contraction of each SMA actuator wire 108 causes the intermediate movable element 106 to move laterally within the cavity and toward another cavity 112. When the movable element 106 moves laterally, the wedge shape of the movable element 106 forces the button 102 to move upward. In other arrangements, the wedge shape can be arranged so that the button moves downward or laterally. The intermediate movable element can cause the button to move, for example, between 20 μm and 0.5 mm. In some embodiments, the button can move up to 1 mm.

[0049] The haptic assembly may include a restoring element 126 that opposes the force of the SMA actuator wire 108. The restoring element 126 may be disposed within the other cavity 112 and may be coupled to the housing 104 at one end and to the movable element 106 at another end. The restoring element 126 (e.g., a return spring or any suitable biasing elastic element) may be arranged to resist contraction of the SMA wire 108, thereby moving the movable element in an opposite direction when the SMA wire 108 is not powered. It should also be understood that the restoring element 126 may include one or more additional SMA wires that, when contracted, pull the movable element 104 in an opposite direction to the plurality of SMA wires 108.

[0050] There may be an end stop 114, which may be formed as part of the housing within the cavity, or may be a separate element within the cavity. The position of the end stop in the cavity may be arranged to limit the movement of the movable element. In general, if the SMA actuator wire is stretched too far (i.e., beyond a certain tension), the SMA actuator wire may become weak or damaged, or even break. The force of the restoring element 126 on the intermediate movable element 110 may cause the SMA actuator wire to become overstretched. Therefore, the end stop 114 may limit the movement of the intermediate movable element 110 so that the SMA actuator wire 108 is not overstretched. Similarly, if there is no end stop, the force applied by the user's finger to the button surface may cause the wire to be overstretched.

[0051] Figure 1b A plan view of another haptic assembly 100' comprising three pairs of parallel SMA actuator wires is shown. The function and structure of the haptic assembly 100' are similar to those of Figure 1a The same as shown, except that the arrangement of the wires is different, so for the sake of simplicity, similar features are not described. In this arrangement, the actuator wires in each pair of actuator wires are connected to opposite sides of the intermediate movable element 106. In some arrangements, opposite sides mean that the actuator wires can be connected to opposite sides of the intermediate movable element 106 parallel to the direction of movement of the intermediate movable element. In other arrangements, opposite sides may mean that the actuator wires can be connected to the same end face of the intermediate movable element, but are located on both sides of the end face. In both arrangements, compared with a single wire connected to one side of the intermediate movable element, the paired wires act in the same direction (i.e., can apply force to the intermediate movable element in the same direction) to provide twice the force.

[0052] The three SMA actuator wires (one of each pair) are connected to the intermediate movable element 106 at one end via a coupling element (or crimp connector - these words are used interchangeably) in the form of a crimp 110c, and are connected to the housing 104 at the other end via a coupling element in the form of a crimp 110a. The pair of crimps 110a, 110c can be considered to form a first pair of coupling elements that connect the three wires to both the intermediate movable element 106 and the housing 104. Each crimp 110a, 110c holds opposite ends of the three wires. In this arrangement, each SMA wire has a direct connection to the housing, but it should be understood that the connection can also be indirect, so there can be one or more intermediate elements between each SMA wire and the housing.

[0053] Similarly, on the opposite side of the movable element (ie, on the Figure 1b One of each pair (not shown) is coupled to the intermediate movable element 106 at one end via a connector or crimp and to the housing 104 at the other end via a connector or crimp. Thus, the three SMA actuator wires are in turn coupled to both the intermediate movable element 106 and the housing via paired coupling members.

[0054] Figure 1c The details of the crimping portion 110a connecting the end of each of the three wires to the housing are schematically shown. Figure 1b Arrows are shown, but it should be understood that Figure 1c The details of the crimping section also apply to Figure 1a In each individual crimp, there are ends of three wires 108a, 108b, 108c. There may be spacing between each wire, and such spacing may be uniform. However, there may also be no spacing or very small spacing between the wires.

[0055] The width w of each crimp may be sufficient to hold and connect to each of the three wires. The crimp width w is the dimension of the crimp parallel to the SMA wire within the crimp. Therefore, the width defines the amount of each SMA wire held in the crimp. The width may be between 400 μm and 750 μm, with a standard crimp typically having a width of 500 μm. For example, a crimp holding three wires may have a standard width. A larger crimp may form a better mechanical connection between the crimp and the wire because there is more crimp material. The length is the dimension of the crimp perpendicular to the width and is defined after the crimp is folded onto the wire. The length is typically 450 μm, i.e., the unfolded crimp is typically 900 μm. The thickness of the crimp may depend on the material. Any suitable material that forms a mechanical and electrical connection may be used for the crimp, such as phosphor bronze or stainless steel. The crimp may be coated with, for example, gold or another suitable material to reduce corrosion and / or reduce the resistance of the electrical connection to the wire. Very thick or thin pieces of material may be more difficult to fold, or may not form a good mechanical connection with the wires. For example, the folded crimp may have a total thickness of 100 μm. The dimensions of the crimp may be selected to balance requirements regarding spacing between wires, and to provide an acceptable mechanical and electrical connection.

[0056] Figure 2a and Figure 2b Schematically shows Figure 1a and Figure 1b Functional arrangement of SMA wires. Figure 2a An example of three looped SMA wires 208a, 208b, 208c is schematically shown. Figure 1a As described, each of the three looped SMA wires may be located within an SMA actuator of a haptic assembly to provide the functionality described above. One end of each wire is connected to the housing 205 via a coupling element 210a (e.g., a crimp connector or a weld). As described above, each wire is looped around a hook, and the other end of each looped wire is connected to the housing 205 via a coupling element 210b (e.g., a crimp connector or a weld). Thus, each coupling element 210a, 210b includes three wires, and each coupling element 210a, 210b is connected to a static part (i.e., the housing). As described above, this connection may be direct as shown, or may be indirect, such as via an intermediate element (not shown).

[0057] Figure 2b An example of an SMA actuator of a haptic component using three pairs of SMA wires (218a, 218f), (218b, 218e), (218c, 218d) is schematically shown. Figure 1bAs described, each of the three pairs of SMA wires may be located within the SMA actuator of the haptic assembly to provide the above functionality. The ends of each pair of SMA wires are connected to a coupling member, which may be a permanent connector, such as a weld or crimp. Coupling members 210a, 210b are connected to the housing (i.e., the static part) and may be referred to as static coupling members. Similarly, coupling members 210c, 210d are connected to the movable element 206 and may be referred to as movable coupling members because they move with the movable element, but not separately. The static coupling member and the movable coupling member form two pairs of coupling members (210a, 210c), (210b, 210d), which couple the SMA wires to both the static element and the movable element. As described above, this coupling may be direct as shown, or may be indirect, for example via an intermediate element (not shown).

[0058] The first pair of SMA actuator wires or the outer pair of SMA actuator wires includes a first outer SMA actuator wire 218a and a second outer SMA actuator wire 218f. The first outer SMA actuator wire 218a is coupled to the intermediate movable element 206 at one end via the first movable coupling member 210c and to the housing at the other end via the first static coupling member 210a. The second outer SMA actuator wire 218f is coupled to the intermediate movable element 206 at one end via the second movable coupling member 210d and to the housing at the other end via the second static coupling member 210b. Similarly, the second pair of SMA actuator wires or the middle pair of SMA actuator wires includes a first middle SMA actuator wire 218b coupled to the first movable coupling member 210c and the first static coupling member 210a, and a second middle SMA actuator wire 218e coupled to the second movable coupling member 210d and the second static coupling member 210b. The third pair of SMA actuator wires or the inner pair of SMA actuator wires includes a first inner SMA actuator wire 218c coupled to the first movable coupling member 210c and the first static coupling member 210a, and a second inner SMA actuator wire 218d coupled to the second movable coupling member 210d and the second static coupling member 210b. Thus, each of the first wires 218a, 218b, 218c in each pair of wires is connected to both the static part and the movable part through the first pair of coupling members 210a, 210c, and each of the second wires 218d, 218e, 218f in each pair of wires is connected through the second pair of second coupling members 210b, 210d.

[0059] exist Figure 1a In (such as Figure 2a ), the halves of the loops act mechanically in parallel, so that each half of each wire can be considered to form an effective line segment. Figure 1a The arrangement in effectively has six wires acting in parallel. Similarly, in Figure 1b (and Figure 2b ), the use of three pairs of wires also provides six wires acting in parallel. Therefore, both arrangements provide the potential to reach six times the force compared to a single wire. This is because the maximum force available is proportional to the diameter of the wire. It should be understood that the SMA force will vary with the load applied to the wire, but some values ​​are provided simply to illustrate the increased force generated by the arrangement. For example, a wire with a cross-section of 25 μm will typically generate a maximum force of 120mN to 200mN, so six wires (or six effective wire segments) will provide a force of approximately 720mN to 1.2N. Increasing the diameter of each wire from 25μm to 35μm approximately doubles the cross-sectional area of ​​each wire, thereby approximately doubling the force provided by each wire. The maximum total force that can be provided by six wires (or six effective wire segments) with a diameter of 36μm is in the range of 1.5N to 3N.

[0060] therefore, Figure 1a and Figure 1b The arrangement can provide significantly higher forces than known SMA actuators without compromising other properties of the assembly, as explained in more detail below. Typically, SMA wires are operated to keep the strain on the SMA wire within a lower limit (e.g., 2%-3%) to prevent damage to the wire. Unless other factors of the SMA wire are changed, providing higher forces with SMA wires may increase the stresses within the wire. For example, the force provided by the SMA wire is related to the cross-section of the wire. Increasing the cross-section of the wire means an increase in the total force available. However, the volume of material that needs to be heated to activate the wire also increases, and in order to obtain higher forces, the power also needs to be adjusted. There is a risk that using higher powers for wires with smaller diameters may damage the wire due to excessive strain. Another issue to be addressed is that wires with larger cross-sections cool more slowly than wires with smaller cross-sections, which may affect performance as described below.

[0061] Figure 3a and Figure 3b The simulated heating and cooling rates are shown for three different arrangements: a single wire with a diameter of 60 μm, three adjacent touching wires with a diameter of 35 μm, and three wires with a diameter of 35 μm but spaced so that the wires are adjacent but not touching. The cross-sectional area of ​​a single wire with a diameter of 60 μm is 2.8×10 -9 m 2 , which is similar to the combined cross-sectional area of ​​the three wires 2.9×l0 -9 m 2 For each of the three wire arrangements, the temperature of the middle wire W2 was simulated separately from the temperature of the outer wire W1, with the simulation parameters being an ambient temperature of 25 degrees Celsius and a cooling start point of 150 degrees Celsius.

[0062] like Figure 3a As shown, there is minimal difference in temperature for both three wire arrangements during the first few milliseconds. The temperature of the middle wire W2 is also similar to the temperature of the outer wire W1. Initially, there is minimal difference in temperature over time for the single wire arrangement compared to the two three wire arrangements. However, after 10 milliseconds, the temperature of the three wire arrangement is approximately 6 degrees cooler than the temperature of the single wire arrangement. Beyond 10 milliseconds, the temperature of the single wire arrangement begins to rise faster than each of the three wire arrangements, so that at 20 milliseconds, there is approximately an 18-20 degree temperature difference.

[0063] The difference between a single-wire arrangement and a three-wire arrangement is even more significant in terms of cooling. Figure 3b As shown, there is minimal difference in their temperature over time as the two three-wire arrangements cool. The temperature of the middle wire W2 is also similar to the temperature of the outer wire W1, with only a relatively small difference (e.g., 5 degrees) between the middle and outer wires in the spaced arrangement after 10 milliseconds, and an even smaller difference (e.g., 2 degrees) between the middle and outer wires in the contact arrangement after 10 milliseconds. The cooling of the three-wire arrangement is much faster than that of the single-wire arrangement, and is approximately 50 degrees lower after 200 milliseconds. For the same total cross-section, the single-wire arrangement takes approximately 3.2 times longer to cool than the three-wire arrangement (i.e., 0.12 seconds vs. 0.38 seconds to cool from 150 degrees to 60 degrees).

[0064] therefore, Figure 3a and Figure 3b It is shown that a three wire arrangement will heat up almost as quickly as a single wire arrangement, so the heating event to activate the actuator and provide contraction to move the movable element is similar for both arrangements. However, for cooling, the three wire arrangement provides a significant advantage over the single wire arrangement. Cooling is much faster, so the wires in the three wire arrangement will cool and return to their original shape faster than the thicker single wire. Therefore, the three wire arrangement is ready to be reactivated faster than the single wire arrangement. Figure 3a and Figure 3b The simulations in also show that when the wires are in contact, the heating and cooling of the three wire arrangement is similar to when the wires are spaced apart, which may be counter-intuitive. In addition, each wire in the multi-wire arrangement is at substantially the same temperature, and therefore there is no performance loss that would be expected if the wires were at different temperatures.

[0065] Thus, in summary, the heating and cooling issues associated with larger diameter wires can be solved by using several smaller diameter wires that provide substantially the same total volume of material, and therefore the same maximum total available force. In addition to being able to provide greater force, the use of multiple wires can also increase the reliability of the device. This is because if one wire breaks in a crimp holding multiple wires, there is still at least one other wire in the crimp that is connected. Due to reliability issues, it is desirable in some industries not to have a single wire.

[0066] Radiator layout

[0067] Figure 4a Shows Figure 1b All unchanged elements retain the same reference numerals, and for the sake of simplicity, the function and structure of these unchanged elements are not repeated. The tactile assembly 100" includes a heat sink 130, which in this arrangement is a separate element on the housing 104 near the SMA wires. A single heat sink is shown, but it should be understood that multiple heat sinks may be combined. The distance between the heat sink and the wires may be less than 5 times the diameter of each wire. More preferably, the distance of the heat sink may be less than 3 times the diameter, and more preferably less than 2 diameters. The heat sink may contact the wires. The heat sink 130 may be made of any suitable material, such as aluminum, phosphor bronze, or steel, which increases the cooling rate of the wires. The heat sink 130 may have a considerable thermal mass and / or high thermal conductivity to achieve enhanced cooling.

[0068] exist Figure 4a In the arrangement schematically shown in , the heat sink is at a small distance from the wire, but it will be appreciated that an arrangement in which the heat sink is in contact with the wire may also be used. Direct contact may increase the cooling rate, but may result in an increase in the power required to instantaneously heat the wire. However, such an arrangement may be desirable for tolerance reasons, as it means that the wire does not have to be positioned with high precision relative to the heat sink.

[0069] The heat sink and / or wire may also be configured to be movable relative to each other between an activation position where the heat sink is adjacent (close to or even in contact with) the wire and an equilibrium position where the heat sink is away from the wire. Before activating the SMA wire, the SMA wire is at room temperature and the heat sink is in an equilibrium position. In this way, the SMA wire can be heated without requiring any additional power. Once the SMA wire is heated, the wire is at a high temperature and the heat sink can be moved from the equilibrium position to the activation position to ensure a good cooling rate for the wire. When the wire cools, additional cooling mechanisms may also be triggered, such as airflow around the wire.

[0070] Figure 4b to Figure 4dis a graph simulating the effect of a heat sink. The cooling and heating rates were calculated for a single wire of 60 μm diameter with the heat sink located within a range of 40 μm to 420 μm from the wire. It will be appreciated that similar results may be obtained for multiple wire arrangements.

[0071] Figure 4b The temperature variation over time for a single wire is plotted when the heat sink is cooled at different distances from the wire. As expected, the presence of the heat sink increases the cooling rate, especially when the heat sink is closer to the wire.

[0072] Figure 4c The temperature is plotted as a function of the distance between the wire and the heat sink at 100 milliseconds and 200 milliseconds after the start of cooling. As expected, the temperature at every location on the heat sink is higher after 100 milliseconds of cooling than after 200 milliseconds of cooling. However, both graphs follow similar curves, with the temperature increasing after a fixed amount of time as the distance between the wire and the heat sink increases. After 200 milliseconds of cooling, the wire will cool from 150 degrees Celsius to 83 degrees Celsius for a wire with a heat sink 250μm away from the wire. After 200 milliseconds of cooling, the wire will cool from 150 degrees Celsius to 70 degrees Celsius for a wire with a heat sink 100μm away from the wire. Therefore, less cooling occurs for a heat sink that is farther away. Similar results are obtained after 100 milliseconds of cooling. Therefore, both graphs show that the proximity of the heat sink can significantly change the cooling rate, and a closer heat sink will improve cooling.

[0073] Figure 4d The temperature change over time when heating a single wire is plotted. As shown, the presence of the heat sink has no significant effect on the short-term heating rate (e.g. before 30 milliseconds) until it is very close, e.g. only 40μm away. In addition, the period of driving the actuator is very short for some applications such as haptics or latches, typically less than 10 milliseconds, and as shown, there is virtually no effect on heating caused by the heat sink. Therefore, any power increase required in such applications is very small because the wire does not need to be kept at a higher temperature for a long time. Therefore, the benefits of cooling rate are not adversely affected by the adverse effects of heating. This is in contrast to other actuators, in which the wire is driven for longer periods of time, and therefore the heat sink is less ideal due to the increased power requirements to heat the wire.

[0074] Crimp arrangement

[0075] In the arrangement shown above, three wires are held together in each individual coupling member (eg, crimp), although as noted above, there may be any number of wires in each coupling member, for example between 2 and 6 (or more). Figure 5is a graph showing recovery time versus displacement for a single 60 μm diameter wire in a crimp, a single 35 μm diameter wire in a crimp, and three 35 μm diameter wires in a crimp. Figure 5 The results in are obtained from experimental data rather than simulation data. Figure 5 As shown, and consistent with the above results, the recovery time of a single 60 μm diameter wire is significantly worse than the other arrangements. Therefore, more time will be required between actuation events to allow the wire to recover to produce the next contraction. The experimental data shows that the recovery time of a single 60 μm diameter wire is about 1.75 times slower than the recovery time of a three 35 μm diameter wire arrangement. This is a smaller difference than the simulation data, but even so the three wire arrangement provides a significantly improved cooling rate compared to a single wire arrangement with a similar cross-section.

[0076] Figure 5 The cooling time for a single 35 μm diameter wire is also shown. As expected, the single thinner wire has a significantly shorter recovery time than each of the arrangements with larger cross-sections. For example, if in each arrangement the contraction of the wire(s) results in a displacement of 40 μm, the 60 μm diameter wire takes approximately 275 milliseconds to recover, the 35 μm diameter wire takes approximately 115 milliseconds to recover, and the three wire arrangement is between these two extremes with a recovery time of approximately 160 milliseconds.

[0077] Figure 1a and Figure 1b Another variation of the arrangement shown in is to hold each wire in its own separate crimp. Figure 6a A variation is shown where each SMA wire has a single crimp. For simplicity, the arrangement of the movable and static elements is not shown, but for ease of assembly, these components are supported on the chassis 600. In this arrangement, there are two pairs of wires (608a, 608c), (608b, 608d). A first pair of upper wires 608a, 608c is arranged above a second pair of lower wires 608b, 608d. Thus, there are two wires on each side of the chassis 600.

[0078] The upper crimping portions 610a, 610b, 610c, 610d each have a lower crimping portion 610a', 610b', 610c', 610d' below it, i.e. the crimping portions are vertically aligned. Each pair of stacked crimping portions (610a, 610a', 610c, 610c'), (610b, 610b', 610d, 610d') at either end of the line can be considered to form a coupling element, and therefore, each coupling element is coupled to multiple lines, although by using different parts, such as a separate crimping portion at each end of each line. The stacked crimping portions (610a, 610a'), (610c, 610c') from the first pair of coupling elements have a first coupling element (610c, 610c') coupling one end of the two wires to the static element, and a second coupling element (610a, 610a') coupling the opposite end of the two wires to the movable element. Similarly, the stacked crimping portions (610b, 610b'), (610d, 610d') from the second pair of coupling elements have a first coupling element (610d, 610d') coupling one end of the two wires to the static element, and a second coupling element (610b, 610b') coupling the opposite end of the two wires to the movable element.

[0079] In this arrangement there are four wires in total, but it will be appreciated that Figure 1b The six-wire arrangement of can be achieved by arranging three wires on either side of the chassis and arranging the corresponding three pairs of crimping parts on either side of the chassis. If the wires are arranged vertically, such as Figure 6a As shown, one on top of the other, the crimping parts can also be arranged in a vertical stack. Similarly, if two wires are required, there can be one wire on each side, or there can be a pair of wires on one side. This arrangement can have 2 to 6 wires in each coupling element including multiple crimping parts.

[0080] The first upper wire 608a is connected at one end to a first upper movable crimp 610a which will be connected to the movable part when the assembly is installed, such as Figure 1b The first upper wire 608a is connected at the other end to a first upper static crimp 610c which will be connected to the static part when the assembly is installed, e.g. Figure 1aSimilarly, the second upper wire 608c is connected at one end to the second upper movable crimp 610b and at the other end to the second upper static crimp 610d. For the lower wires, the first lower wire 608b is connected at one end to the first lower movable crimp 610a' and at the other end to the first lower static crimp 610c', and the second lower wire 608d is connected at one end to the second lower movable crimp 610b' and at the other end to the second lower static crimp 610d'.

[0081] The wires and crimping parts are arranged in a vertical stack, which achieves a good separation of the wires, which may be advantageous for the cooling rate as described above. However, the overall height is increased by using vertical stacking. In addition, there are additional parts (i.e., more crimping parts) and additional assembly steps. Some of the crimping parts, such as the movable crimping parts 610a, 610b, 610a', 610b', can be formed integrally with the chassis 600 to reduce the total number of parts. In order to assist in assembling some of the crimping parts, such as the static crimping parts 610c, 610d, 610c', 610d', can be formed on a separate tab 602, which is attached (e.g., welded) to the chassis 600 during the assembly procedure.

[0082] Figure 6b Shows Figure 6a A variation of the arrangement in which each SMA wire in the two pairs of wires (618e, 618c), (618b, 618d) has a single crimp. In this arrangement, the wires are still arranged in a vertical stack on either side of the chassis 600, but the upper and lower crimps are offset both laterally and vertically and are therefore not arranged in a vertical stack as in the previous arrangement. It should be understood that this is just one arrangement and that the crimps may be offset only laterally or only vertically, not necessarily both as shown.

[0083] The crimping portions (620a, 620a'), (620c, 620c') from the first pair of coupling elements have a first coupling element (620c, 620c') coupling one end of the two wires to the static element and a second coupling element (620a, 620a') coupling the opposite end of the two wires to the movable element. Similarly, the crimping portions (620b, 620b'), (620d, 620d') from the second pair of coupling elements have a first coupling element (620d, 620d') coupling one end of the two wires to the static element and a second coupling element (620b, 620b') coupling the opposite end of the two wires to the movable element.

[0084] The first upper wire 618a is connected at one end to the first upper movable crimp 620a and at the other end to the first upper static crimp 620c, which will be connected to the movable part when the assembly is installed. Similarly, the second upper wire 618c is connected at one end to the second upper movable crimp 620b and at the other end to the second upper static crimp 620d. For the lower wires, the first lower wire 618b is connected at one end to the first lower movable crimp 620a' and at the other end to the first lower static crimp 620c', and the second lower wire 618d is connected at one end to the second lower movable crimp 620b' and at the other end to the second lower static crimp 620d'.

[0085] As shown, the upper wire is shorter than the lower wire because the upper crimps are positioned closer together than the corresponding lower crimps. It should be understood that if each upper crimp is laterally offset from the lower crimp in the same direction, similar spacing can be obtained between the upper and lower crimps. Therefore, similar offset arrangements can be used for wires of the same length. However, in some designs, it may be useful to have wires of different lengths.

[0086] and Figure 6a Similarly, arranging the wires and crimps in this manner allows for good separation of the wires. Likewise, the overall height can be increased by separating the wires vertically, but the lateral offset means that the crimps can be formed at the same time. This compromise may result in an overall increase in actuator width. As previously discussed, some of the crimps, such as the movable crimps 620a, 620b, 620a', 620b' may be formed integrally with the chassis 600 to reduce the total number of components. To assist in assembling some of the crimps, such as the static crimps 620c, 620d, 620c', 620d' may be formed on a separate tab 602 that is attached to the chassis 600 during the assembly procedure.

[0087] It should be understood that the selection of the number of wires in the figures shown above is merely exemplary, and that additional or fewer wires may be used. Using additional wires, especially if they are a single crimp, may increase the size of the assembly, so a balance between the number of wires and the overall size is considered when designing the assembly. An arrangement with multiple crimps and multiple wires may have similar performance in terms of generated forces to an arrangement with the same number of wires held in a smaller number of wires, but as Figure 5The arrangement of multiple crimps may have an increased cooling rate. However, the arrangement of multiple crimps may increase cost due to the additional material, the increase in assembly steps if the crimps are formed sequentially, and the increase in assembly size. In an apparatus incorporating such an SMA actuator, space is often limited, so the increase in size may not be desirable. However, the design may be selected to balance the desired cooling rate and other factors.

[0088] Third haptic component

[0089] Figure 7 A ("third") haptic assembly is shown that operates in a different manner than the haptic assemblies described above.

[0090] The third haptic assembly includes a movable element 706 mounted above a static element 704. Adjacent faces of the movable element and the static element have complementary shapes.

[0091] The third haptic assembly includes a plurality of wires 708 (only one of which is visible in the figure). Each wire is attached to a static element 704 at its end. Both ends of each wire are attached using a static coupling element 712a in the form of a crimp connector, wherein the same crimp connector preferably holds two or more of the plurality of wires 708. Each wire 708 defines a plurality of line segments 708a, 708b (in this case, ten line segments). The first plurality of line segments 708a are generally parallel to each other, and the second plurality of line segments 708b are generally parallel to each other and are set, for example, at right angles to the other line segments 708a. Therefore, the line segments 708a, 708b can be considered to form a V-shaped pair of line segments 708a, 708b.

[0092] Each of the wire segments 708a, 708b is engaged with the static element 704 and the movable element 706. A first end of the first wire segment 708a is attached to the static element 704 using a crimp connector 712a, and the other end of the first wire segment 708a is engaged with the movable element 704 via, for example, a locating pin 714. Similarly, a first end of the final wire segment 708b is engaged with the movable element 706 via a locating pin 714, and the other end of the final wire segment 708b is attached to the static element 704 using a crimp connector 712a. Each of the other wire segments 708a, 708b is engaged with the static element 704 at one end via a locating pin 712b (or other type of non-fixed connector, such as a hook), and is engaged with the movable element 706 at the other end via a locating pin 714.

[0093] The V-shape is located within a channel having a sawtooth shaped cross section. It will be appreciated that if the line segments are designed to have different shapes, the channel may similarly be designed to have a complementary matching shape.

[0094] The plurality of wires 708 may be evenly spaced, may be parallel to one another and / or aligned in separate channels (or a single channel) between the static element 704 and the movable element 706 .

[0095] It should be understood that when the plurality of wires 708 are contracted, the movable element 706 moves in a direction (upward) that is, for example, 90° to the direction in which the wires 708 generally extend (horizontally).

[0096] manufacture

[0097] Figure 8 is a schematic diagram of a method that can be used to crimp multiple wires in a single crimp in the above-described SMA actuator. Multiple spools 70, 72, 74 simultaneously feed the wires through guide wheels 76 and into crimp 78. The guide wheels can help maintain the spacing between the wires in the crimp. Each wire can be made of any suitable shape memory alloy and can be coated (e.g., with polyimide or similar materials) to reduce the risk of the wires shorting to other components in the SMA actuator when they come into contact with them. The number of wires is shown as three, but it should be understood that this is merely exemplary and other numbers of wires can be used.

[0098] For best performance, the axis of each wire is preferably parallel to the axis of the crimp, but due to imperfections in the crimp, each wire is typically expected to leave the crimp at an angle. Wire bending at the crimp point increases fatigue. Guide wheels can also help keep each wire at a desired angle relative to the crimp. Slight deviations from parallelism may be acceptable. The magnitude of the deviation depends on the thickness of the wire, but for a 25μm diameter wire, the deviation may be as high as 8 degrees of parallelism. Also, the angle variation between each wire can be within this range. If each wire can be fed into the crimp at an acceptable angle, the guide wheels can be omitted.

[0099] Once the wire is within the crimp, the crimp may be crimped (i.e., folded or closed) to create a mechanical and electrical connection between the wire and the crimp. Any excess wire protruding from the crimp may then be trimmed. The crimping step may be performed at any suitable point in the assembly process.

[0100] The same procedure can be used to connect the same wire to a second crimp (e.g., as shown in FIGS. 6 and 7). Figure 7 The crimping portion in the tactile component).

[0101] When the crimp(s) are closed, the tension in each wire between the crimps and / or the length of each of the plurality of SMA wires is controlled so that in the final assembly, each wire has substantially the same tension and / or length between the crimps. As described above, this can be accomplished by arranging the plurality of SMA wires to each follow an equivalent parallel path.

[0102] Generally speaking, if the wires do not cross (i.e., pass over each other), a more reliable haptic assembly can be manufactured. However, in some cases (e.g., in mass production), it may not be practical to completely prevent crossing. In such cases, the inventors have found that even if the wires cross between the first crimp and the second crimp, satisfactory reliability can be achieved as long as the wires do not cross inside the crimp.

[0103] As an alternative to crimping, welding (e.g., arc welding, welding using a welding rod, laser / heat-based welding) can be used to connect the ends of the wires in place (e.g., directly to a static element or a movable element or an intermediate element). By welding the wires in place, the spacing between the wires can be more precisely controlled. During the welding procedure, the weld needs to be carefully controlled so that damage to the wires (e.g., melting or material loss) is minimized.

[0104] Those skilled in the art will appreciate that, although the foregoing description has been described as the best mode and other appropriate modes for carrying out the present technology, the present technology should not be limited to the specific configurations and methods disclosed in the description of the preferred embodiment. Those skilled in the art will recognize that the present technology has a wide range of applications, and that the embodiments can be widely modified without departing from any inventive concept as defined in the appended claims.

Claims

1. A shape memory alloy (SMA) actuator, comprising: Static components; a movable element capable of moving relative to the static element; a plurality of SMA wires each coupled to one or both of the static element and the movable element and causing movement of the movable element when contracted; as well as a coupling element coupling at least two wires from the plurality of SMA wires to one of the static element and the movable element; Wherein, the coupling element comprises a crimping connector for holding the at least two wires.

2. The SMA actuator of claim 1, wherein: The crimp connector holds between two wires and six wires.

3. An SMA actuator according to claim 1 or claim 2, wherein: The crimp connector has a width between 500 μm and 750 μm.

4. The SMA actuator according to any one of claims 1 to 3, comprising: a first crimp connector connecting one end of each of the at least two wires to the static element or the movable element; and a second crimp connector connecting the other end of each of the at least two wires to the static element or the movable element.

5. The SMA actuator of claim 4, wherein: The first crimp connector and the second crimp connector are of the same type.

6. An SMA actuator according to claim 4 or claim 5, comprising a plurality of pairs of first and second crimp connectors, wherein each pair of crimp connectors connects each of at least two wires to one or both of the static element and the movable element.

7. The SMA actuator of claim 6, comprising a first pair of crimp connectors connecting each of a first set of at least two wires to the movable element, and a second pair of crimp connectors connecting each of a second set of at least two wires to the movable element, wherein when the first set of at least two wires is contracted, the movable element moves in a first direction, and when the second set of at least two wires is contracted, the movable element moves in a direction opposite to the first direction.

8. The SMA actuator of claim 6, comprising a first pair of crimp connectors connecting each of a first set of at least two wires to the movable element, and a second pair of crimp connectors connecting each of a second set of at least two wires to the movable element, wherein the movable element moves in one direction when the wires connected to the first pair of crimp connectors and the second pair of crimp connectors contract.

9. An SMA actuator according to any one of claims 4 to 6, wherein: The first crimp connector connects one ends of the at least two wires to a first region of the static element, the second crimp connector connects the other ends of the at least two wires to a second region of the static element, the at least two wires extend generally in a first direction, and when the plurality of SMA wires contract, the movable element moves in a direction that forms an acute angle greater than zero with the first direction.

10. An SMA actuator according to any one of claims 4 to 9, wherein: The at least two SMA wires do not cross between the first crimping portion and the second crimping portion.

11. An SMA actuator according to any one of claims 4 to 9, wherein: The at least two SMA wires do not cross inside the crimp connector, but cross between the first crimping portion and the second crimping portion.

12. An SMA actuator according to any one of claims 1 to 11, wherein: The at least two SMA wires do not cross inside the crimp connector.

13. An SMA actuator according to any one of claims 1 to 12, wherein: The at least two wires extend generally parallel to each other between the crimp connectors.

14. An SMA actuator according to any one of the preceding claims, wherein: The coupling element provides a direct connection between the at least two wires and one of the static element and the movable element.

15. An SMA actuator according to any one of the preceding claims, wherein: The coupling element couples the at least two wires to an intermediate member to provide an indirect connection between the at least two wires and one of the static element and the movable element.

16. The SMA actuator of any preceding claim, further comprising at least one heat sink adjacent the plurality of SMA wires.

17. The SMA actuator of claim 16, wherein: The at least one heat sink is located at a distance from the plurality of wires that is less than five times the diameter of each wire.

18. An SMA actuator according to claim 16 or claim 17, wherein: The at least one heat sink contacts the plurality of SMA wires.

19. An SMA actuator according to any one of claims 16 to 18, wherein: The at least one heat sink and / or the plurality of wires are movable relative to each other between a first position in which the heat sink is adjacent to or in contact with the plurality of wires and a second position in which the heat sink is remote from the plurality of wires.

20. A haptic component comprising: Touchable parts; as well as An SMA actuator according to any one of claims 1 to 19, wherein when a user presses the touchable component, an actuator module is activated to provide tactile feedback to the user by moving the touchable component using the movable element.

21. A latch comprising a SMA actuator according to any one of claims 1 to 19.

Images