Tactile buttons

Abstract

In general, embodiments of the present technology provide apparatus and methods for providing tactile feedback, and more particularly, relate to user-operated buttons for electrical and electronic products that provide tactile feedback to the user when operated.

Description

[0001] The present application relates generally to apparatus and methods for providing tactile feedback, and more particularly to user-operated buttons for electrical and electronic products that provide tactile feedback to the user when operated.

[0002] Consumer electronic devices use buttons of different designs to give users tactile feedback about button operation, that is, feedback that the user can feel by touch. In the case of a button, this tactile feedback can be the touch or force that the user feels by the finger operating the button.

[0003] In the case of computer keyboards and smartphone buttons, the most popular designs are dome switches and leaf springs, which provide tactile feedback due to the mechanical response of the components changing the resistance felt by the user against a button press. The exact force profile of the resistance during the operation itself is often tuned into the mechanical design to meet the preferences of the target user.

[0004] In mobile consumer electronic devices, space is very tight, so it is advantageous to produce buttons or switches with a very low profile. Low profile buttons must have a small travel distance, so the range of producing a satisfactory tactile response to the user is small, especially if it is also desired to have a low or near zero force requirement to make and / or maintain electrical contact.

[0005] The common mechanical buttons on the front of many smartphones, such as dome switches and leaf spring switches, have been replaced by capacitive buttons. In this technology, the buttons do not need to protrude from the device, and the force requirement to establish electrical contact is zero. This allows for a smooth mechanical design of the smartphone casework and reduces user fatigue if the user presses the button multiple times in a short period of time. However, unlike mechanical designs, these products are completely mechanically passive and therefore do not provide any tactile feedback. In addition, a mechanical switch can be configured to detect the force applied to it, thereby allowing multiple functions to be applied to a single device depending on the force used or the duration the switch is pressed; capacitive buttons cannot do this.

[0006] The applicant has identified a need for a button that can provide tactile feedback in a compact button design and that can be operated with a very small amount of button travel.

[0007] According to the first method of the present technology, a button assembly is provided, comprising: a button having a depressible surface; a contact portion below the button, which is depressible; a sensor arrangement, which is arranged to sense the depression of the contact portion; a shape memory alloy actuator, which is arranged to drive the movement of the button relative to the contact portion in a lateral direction relative to the stroke direction when the button is pressed; at least one main bearing element, which is arranged to contact and depress the contact portion when the button is pressed, and when the button is pressed, carry the movement of the button in the lateral direction without interrupting the contact with the contact portion.

[0008] The button assembly of the present technology includes a contact portion that detects contact between a user (e.g., a user's finger) and a button. The contact portion is disposed below the button, and the contact portion may be depressed, deflected, or bent when the user presses the button. The contact portion may be, for example, a thin layer of material (e.g., a thin metal sheet) that may be depressed, deflected, or bent when the button is pressed, or a plunger-like element that may apply force to another element when the button is pressed. The button assembly also includes a sensor device that is arranged to sense / detect depression / deflection / bending of the contact portion. In an embodiment, the contact portion may be electrically connected to the sensor device when the contact portion is depressed / deflected / bent. When the sensor device senses / detects that the shape, form, or arrangement of the contact portion has changed, the sensor device may transmit the information to the control circuit so that a drive signal is applied to the shape memory alloy actuator (to drive the button relative to the movement of the contact portion).

[0009] When the button is pressed, the button assembly can use the sensor device to sense the depression of the contact portion. Therefore, the button assembly can not use a capacitive sensor, but can be operated by a button, and when pressed, the button experiences a certain degree of travel.

[0010] The button assembly uses a shape memory alloy actuator to drive the movement of the button in the lateral direction relative to the direction of travel when the button is pressed. When the button is pressed, this movement in the lateral direction can be used to provide a tactile effect. In particular, this movement in the lateral direction can give the user a tactile sensation, which can be perceived as a change in the resistance to the pressing of the button, even if the downward movement of the button is minimal. In addition, since the SMA actuator is used to provide the tactile effect, the button assembly may not need to incorporate a mechanical device to control the resistance to the pressing of the button. This can allow a compact, low-profile design of the button assembly, in which the travel of the button can be minimized. The sensor device can be very simple because it only senses the depression of the contact portion.

[0011] The use of shape memory alloys (SMA) as actuators (e.g., in the form of SMA wire) provides high force and fast response, which is suitable for providing tactile effects that can be sensed by a user, but in a very compact form due to the relatively high force / size ratio of the SMA material.

[0012] However, when an SMA actuator is used to drive the movement of a button, there is still a need to provide reliable button operation that is not affected by the button travel. The present technology can achieve this by providing a main bearing element that contacts and depresses the contact portion when the button is pressed, wherein the main bearing element also carries the movement of the button in a lateral direction when the button is pressed without interrupting the contact with the contact portion. This use of a bearing element to depress the contact portion and carry the movement of the button in a lateral direction ensures reliable operation of the button while providing a tactile effect.

[0013] Advantageously, the main bearing element may continuously contact the contact portion and support the button thereon. This arrangement may have the advantage of reducing the button travel required to depress the contact portion, as there is no loss of travel between the button and the contact portion. Accordingly, both the travel and size of the button assembly may be reduced. In certain applications, it may be beneficial to ensure that contact is maintained rather than intermittent. For example, a button may be used in an application where precise timing of button presses is required, for example, when controlling a computer game. Similarly, this may be advantageous in applications where multiple functions are assigned to a button, which functions occur by pressing the button for different periods of time.

[0014] Advantageously, the primary bearing element may be aligned with the geometric center of the depressible surface. This helps transfer the force applied to the button to the contact portion.

[0015] In one arrangement, the button assembly may further include: at least one elastic element arranged transversely beside the primary bearing element; at least one secondary bearing element in contact with the elastic element and supporting the button thereon, the elastic element being arranged to accommodate the travel of the button, and at least one secondary bearing element being arranged to carry said movement of the button in the transverse direction. In this arrangement, the elastic element reduces the tilt of the button when it is pressed.

[0016] The reduction of tilting can be improved by arranging the secondary bearing element on the opposite side of the main bearing element. In this case, the secondary bearing element is preferably arranged on the opposite side of the main bearing element in the transverse direction, and the shape memory alloy actuator is arranged to drive the movement in this transverse direction. In this way, the secondary bearing element carries the movement of the button in the transverse direction more effectively.

[0017] In another arrangement, the button assembly may further include: a support on which the contact portion is mounted; and at least one stopper element protruding from the button, the at least one stopper element being spaced from the support by a gap that limits the tilt of the button. In this arrangement, the stopper element reduces the tilt of the button when it is pressed.

[0018] The reduction of tilting can be improved by arranging the stopper element on the opposite side of the main bearing element. In this case, the stopper element is preferably arranged on the opposite side of the main bearing element in the lateral direction and the shape memory alloy actuator is arranged to drive the movement in this lateral direction. In this way, the stopper element carries the relative lateral movement of the button more effectively.

[0019] Advantageously, both ends of the shape memory alloy wire may be fixed relative to the contact portion, and the shape memory alloy wire may be hooked around a retaining portion formed on the button at an intermediate position. In this case, the two portions of the shape memory alloy wire extending from the retaining portion may be arranged to drive the movement of the button in a lateral direction in parallel. This increases the force applied by the SMA wire while maintaining a compact arrangement. In this case, the following features may be additionally applied in any combination to obtain a compact arrangement:

[0020] • The two sections of the shape memory alloy wire extending from the retaining portion can be located below the depressible surface of the button. This minimizes the footprint of the button assembly.

[0021] • The main bearing may be located between two portions of the shape memory alloy wire extending from the retaining portion.

[0022] The button assembly may further comprise at least one resilient biasing element arranged to resiliently bias the shape memory alloy actuator, in which case the at least one resilient biasing element may also be located between two portions of the shape memory alloy wire extending from the retaining portion.

[0023] The bearing element may be any suitable type of bearing. For example, the bearing element may be a bearing ball protruding from the button or a plain bearing member. The use of a plain bearing member has particular advantages in providing a simple and compact arrangement without compromising the bearing function. The use of a bearing ball has the particular advantage of a relatively low degree of friction and may therefore be preferred in applications where the force requirements are relatively high. For example, the bearing element may be a flexure, a flex pin or a roller pin.

[0024] The SMA actuator may include an SMA wire. The diameter of the SMA wire is selected to provide a desired balance of force, stroke, and efficiency. The SMA wire preferably has a diameter of 100 microns or less, or more preferably has a diameter of 35 microns or less.

[0025] The sensor arrangement may be of any type suitable for sensing depression of a contact portion when the button is pressed.Ideally, the sensor arrangement is provided with a simple construction which minimises the travel and size of the button assembly.

[0026] One possibility is that the contact portion comprises a first switch element and the sensor device comprises a second switch element which is arranged such that depression of the contact portion causes the switch element to make electrical contact. This and its simple switch device achieves a sensor device which is reliable and meets the desire to minimize the stroke and size of the pushbutton assembly.

[0027] An alternative is that the sensor device comprises a strain gauge, which can be fixed, for example, to the contact portion. This alternative also implements the sensor device with an extremely simple switch device, which is reliable and meets the desire to minimize the stroke and size of the pushbutton assembly.

[0028] For example, the strain gauge may include a thin sheet whose resistance changes as the sheet is strained. In this case, the height of the button assembly is minimized because the sheet itself may be relatively thin, so only enough clearance needs to be provided to accommodate depression of the contact portion.

[0029] According to a second method of the present technology, a method for delivering tactile sensation using a button assembly of the type described herein is provided, the method comprising: sensing depression of a contact portion; and applying a drive signal to a shape memory alloy actuator to drive movement of the button relative to the contact portion.

[0030] The method may include, prior to applying the drive signal, selecting the drive signal from a set of drive signals, wherein each drive signal provides a specific haptic effect.

[0031] According to a third method of the present technology, a circuit for transmitting tactile sensation using a button assembly of the type described in this article is provided, the circuit comprising: a detection module for sensing depression of a contact portion; and a drive module for applying a drive signal to a shape memory alloy actuator to drive movement of the button relative to the contact portion.

[0032] Prior to applying the drive signal, the drive module may select the drive signal from a set of drive signals, where each drive signal provides a specific haptic effect.

[0033] In a related method of the present technology, a non-transitory data carrier is provided that carries processor control code to implement any of the methods described herein.

[0034] Preferred features are set out in the dependent claims.

[0035] As will be appreciated by those skilled in the art, the present technology can be embodied as a system, method or computer program product.Therefore, the present technology can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects.

[0036] Furthermore, the present technology may take the form of a computer program product embodied in a computer readable medium having computer readable program code embodied thereon. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. The computer readable medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared or semiconductor system, apparatus or device, or any suitable combination of the foregoing.

[0037] Computer program code for performing operations of the present technology may be written in any combination of one or more programming languages, including object-oriented programming languages ​​and traditional procedural programming languages. Code components may be embodied as procedures, methods, etc., and may include subcomponents that may take the form of instructions or sequences of instructions at any level of abstraction from direct machine instructions of a native instruction set to high-level compiled or interpreted language constructs.

[0038] Embodiments of the present technology also provide a non-transitory data carrier carrying code, which, when implemented on a processor, causes the processor to perform any of the methods described herein.

[0039] The techniques also provide processor control code to implement the above methods, for example, on a general purpose computer system or a digital signal processor (DSP). The techniques also provide a carrier carrying processor control code to implement any of the above methods at runtime, particularly on a non-transitory data carrier. The code may be provided on a carrier such as a disk, a microprocessor, a CD-ROM or a DVD-ROM, a programming memory such as a non-volatile memory (e.g., flash memory) or a read-only memory (firmware), or provided on a data carrier such as an optical or electrical signal carrier. The code (and / or data) implementing the embodiments of the techniques described herein may include source, object or executable code in a conventional programming language (interpreted or compiled) such as C, or assembly code, code for setting or controlling an ASIC (application specific integrated circuit) or an FPGA (field programmable gate array), or code for a hardware description language such as Verilog (RTM) or VHDL (very high speed integrated circuit hardware description language). As will be appreciated by the skilled person, such code and / or data may be distributed between multiple coupled components that communicate with each other. These techniques may include a controller including a microprocessor, working memory, and program memory coupled to one or more components of the system.

[0040] It will also be clear to those skilled in the art that all or part of the logic method according to the embodiments of the present technology can be appropriately embodied in a logic device including a logic element that performs the steps of the above method, and such a logic element can include, for example, a component in a programmable logic array or an application-specific integrated circuit, such as a logic gate. Such a logic arrangement can further be embodied in an enabling element for temporarily or permanently establishing a logic structure in such an array or circuit using, for example, a virtual hardware descriptor language, which can be stored and transmitted using a fixed or transmittable carrier medium.

[0041] In an embodiment, the present technology can be implemented in the form of a data carrier having functional data thereon, the functional data comprising a functional computer data structure to enable the computer system to perform all the steps of the above-described method when loaded into a computer system or network and operated thereby.

[0042] Implementations of the present technology will now be described by way of example with reference to the accompanying drawings, in which:

[0043] Figure 1 is a perspective view of a first button assembly;

[0044] Figure 2 is an exploded perspective view of a first button assembly;

[0045] Figure 3 is a schematic diagram of a control circuit of a first button assembly;

[0046] Figure 4 is a side view of a first button assembly;

[0047] Figure 5 yes Figure 3 The enlarged part of

[0048] Figure 6 is a side view of a first button assembly having a modified form of bearing;

[0049] Figure 7 yes Figure 5 The enlarged part of

[0050] Figure 8 is an exploded perspective view of a second button assembly;

[0051] Fig. 9 is a cut-away perspective view of a second button assembly;

[0052] Fig.10 is a cross-sectional side view of the second button assembly showing Fig. 9 a cutaway portion of

[0053] Fig.11 is along Fig. 9A cross-sectional top view of the second button assembly taken along line XX; and

[0054] Fig.12 is a schematic diagram of the control circuit of the second button assembly.

[0055] Two button assemblies are described. In each case, the button assembly includes a contact portion that detects contact between a user (e.g., a user's finger) and a button. The contact portion is disposed below the button, and when the user presses the button, the contact portion may be depressed, deflected, or bent. The contact portion may be, for example, a thin layer of material (e.g., a thin sheet of metal) that may be depressed, deflected, or bent when the button is pressed, or a plunger-shaped element that may apply force to another element when the button is pressed. The button assembly also includes a sensor device that is arranged to sense / detect depression / deflection / bending of the contact portion. In an embodiment, the contact portion may be electrically connected to the sensor device when the contact portion is depressed / deflected / bent. When the sensor device senses / detects that the shape, form, or arrangement of the contact portion has changed, the sensor device may transmit the information to the control circuit so that a drive signal is applied to the shape memory alloy actuator (to drive the button relative to the movement of the contact portion).

[0056] The first button assembly 10 is Figure 1 and Figure 2 , and are arranged as follows.

[0057] The first button assembly 10 comprises a button 11 having a depressible surface 12, which in this example is circular. The button 11 may be formed from a single sheet of material.

[0058] The first button assembly 10 may be arranged in a housing (not shown) and / or may be integrated into an electronic device. In either case, the depressible surface 12 is exposed so that it can be pressed by a user.

[0059] The first button assembly 10 includes a laminate structure 13 which is provided below the button 11 and is arranged as follows.

[0060] The laminated structure 13 includes a contact layer 14 immediately below the depressible surface 12. The contact layer 14 is depressible and serves as a contact portion. The contact layer 14 is made of a spring metal such as phosphor bronze.

[0061] In order below the contact layer 14, the laminate structure 13 further includes a first insulating layer 15, a switch layer 16, and a second insulating layer 17. The first insulating layer 15 separates the contact layer 14 and the switch layer 16, and has a hole 18 aligned with the button 11. The contact layer 14 is pressed down into the hole 18 so that the contact layer 13 is in electrical contact with the switch layer 16. Therefore, the contact layer 14 and the switch layer 16 act as a first switch element and a second switch element. The electrical contact can be sensed, so the switch layer 16 acts as a sensor device to sense the depression of the contact layer 14 in the first button assembly 10.

[0062] In general, any other form of sensor arrangement, such as strain gauges, may be used instead.

[0063] The first button assembly 10 includes an SMA wire 20. Both ends of the SMA wire 20 are fixed relative to the contact layer 14 by being curled by a curling portion 21 mounted on an insulating block 22. The SMA wire 20 is hooked around a holding portion 23 formed on one side of the button 11 at a middle position. Therefore, the two portions 24 of the SMA wire 20 extending from the holding portion 20 extend transversely to the stroke direction of the button 11. Therefore, the two portions 24 of the SMA wire 20 act in parallel when they are contracted to drive the movement of the button 11 relative to the contact layer 13 in a transverse direction (preferably orthogonal) relative to the stroke direction when the button 11 is pressed.

[0064] The diameter of the SMA wire 20 is selected to provide a desired balance of force, stroke, and efficiency. The SMA wire 20 preferably has a diameter of 100 microns or less, or more preferably has a diameter of 35 microns or less. Although the first button assembly 10 includes a single SMA wire 20, any number of SMA wires may generally be included.

[0065] The coil spring 25 is connected to the button 11 at one end on the side opposite to the SMA wire 20. The coil spring 25 is fixed relative to the contact layer 14 at its other end and is arranged to be in a tensioned state. Therefore, the coil spring 25 serves as an elastic biasing element for elastically biasing the SMA wire 20. Generally, any number of springs may be included and / or any other form of elastic bias may be provided, such as a compressed coil spring, a leaf spring and / or a flexure.

[0066] When the button 11 is pressed, the movement of the button 11 in the lateral direction is used to provide a tactile effect. In particular, this movement of the button 11 in the lateral direction gives the user a tactile sensation, which can be perceived as a change in the resistance against the pressing of the button 11, even if the downward movement of the button 11 is minimal.

[0067] Figure 3A control circuit 30 is shown for the first button assembly 10. The control circuit 30 is connected to the contact layer 14 and the switch layer 16 and detects when electrical contact occurs between the contact layer 14 and the switch layer 16 by pressing the button 11, causing the contact layer 14 to be depressed. More insulator and conductor layers may be added to form a force sensitive switch, which may further reduce the travel of the button.

[0068] The control circuit 30 is also connected to the SMA wire 20 and applies a drive signal thereto. In use, in response to detecting a depression of the button 11, the control circuit 30 drives the SMA wire 20 to move the button 11.

[0069] The drive signal resistively heats the SMA wire 20, causing it to contract. Due to the biasing effect of the coil spring 25, when the drive signal ceases, the SMA wire 20 cools, causing it to expand. The resulting movement of the button 11 in the lateral direction can be felt by a user pressing the button 11, thereby providing a tactile effect. The tactile effect is a tactile sensation that allows the user to feel that the button 11 is being pressed downward even if the downward travel is minimal.

[0070] Various forms of drive signals may be used to provide different tactile effects, such as a single pulse to provide a single movement of the button 11 , or multiple pulses to provide a vibrating movement of the button 11 .

[0071] The first button assembly 10 further comprises a bearing arrangement 40 arranged between the button 11 and the laminate structure 13 for carrying the button 11 on the contact layer 14 .

[0072] The bearing arrangement 40 is located in a groove 41 formed in the bottom of the button 11. The bearing arrangement 40 includes an insulating layer 42 disposed on the surface of the button 11, wherein a bearing layer 43 on the top is formed of a suitable hard material (such as metal). The primary bearing ball 44 and the secondary bearing ball 45 are disposed between the bearing layer 43 and the contact layer 14 and contact them to carry the button 11 on the contact layer 14, as described in more detail below.

[0073] The main bearing ball 44 and the auxiliary bearing ball 45 are positioned by a retaining piece 46' disposed in the recess 41. The retaining piece 46' has a hole 47 in which the main bearing ball 44 and the auxiliary bearing ball 45 are disposed.

[0074] There are two main bearing balls 44 arranged along a centerline aligned with the geometric center of the depressible surface 12 of the button 11, which helps transfer force from the button 11 to the contact layer 14. Generally, there can be any number of one or more main bearing balls 44, but by providing a plurality of main bearing balls 44, the main bearing balls 44 resist tilting in the centerline direction (the main bearing balls 44 are arranged along the centerline).

[0075] The main bearing ball 44 continuously contacts the contact layer 14 and supports the button 11 thereon. Therefore, when the button 11 is pressed, the button 11 does not lose travel before the contact layer 14 is contacted, and the main bearing ball 44 immediately presses down the contact layer 14. In addition, when the button 11 is pressed, the main bearing ball 44 acts as a bearing and carries the movement of the button 11 in the lateral direction driven by the SMA wire 20 without interrupting the contact with the contact layer 14.

[0076] The secondary bearing ball 45 is arranged to reduce the tilt of the button 11 when the button 11 is pressed, as described below.

[0077] like Figure 4 and Figure 5 As best shown in FIG. 1 , the contact layer 14 is formed as a spring arm 46 at a lateral position beside the primary bearing ball 44, aligned with the secondary bearing ball 45. The spring arm 46 is offset upward from the remainder of the contact layer 14. The secondary bearing ball 45 contacts the spring arm 46, which thus supports the secondary bearing ball 45 and acts as an elastic element that accommodates the travel of the button 11 when the button 11 is pressed. In addition, when the button 11 is pressed, the secondary bearing ball 45 acts as a bearing and carries the movement of the button 11 in the lateral direction driven by the SMA wire 20. Since the secondary bearing ball 45 and the spring arm 46 are disposed laterally beside the primary bearing ball 44, they reduce the tilt of the button 11 along the lateral direction of the movement of the button 11 in the lateral direction. By disposing the secondary bearing ball 45 on the opposite side of the primary bearing ball 45 along the lateral direction of the movement of the button 11 in the lateral direction, the tilt reduction is improved.

[0078] Since the spring arm 46 is offset upward from the remainder of the contact layer 14, the diameter of the primary bearing ball 44 is greater than the diameter of the secondary bearing ball 45. Since the travel of the contact layer 14 required to make contact when the button 11 is pressed is limited by the thickness of the insulating layer 15, the difference in diameter between the primary bearing ball 44 and the secondary bearing ball 45 needs to be greater than the thickness of the insulating layer 15.

[0079] In general, the spring arm 46 may be replaced by any other resilient element that provides a similar effect, such as a single piece of resilient material.

[0080] In the bearing arrangement 40, preferably the surfaces of the load-bearing layer 43, the contact layer 14 and the spring arms 46 are selected so that they have a similar hardness to the primary bearing balls 44 and the secondary bearing balls 45 with which they contact, to prevent wear.

[0081] Although the primary bearing ball 44 and the secondary bearing ball 45 function as bearing elements in the first button assembly 10 , they may be replaced by any other forms of bearing elements that provide a bearing function.

[0082] exist Figure 6 and Figure 7In one example shown, the main bearing ball 44 and the secondary bearing ball 45 are replaced by a main sliding bearing member 48′ and a secondary sliding bearing member 48, which protrude from the button 11 and serve as bearing elements having the same function and effect as the main bearing ball 44 and the secondary bearing ball 45. The main sliding bearing member 48′ and the secondary sliding bearing member 48 may be formed integrally with the button 11. The main sliding bearing member 48′ and the secondary sliding bearing member 48 may be made of or coated with a low surface energy material (e.g., polytetrafluoroethylene (PTFE)) so that there is a low coefficient of friction between the bearing surfaces.

[0083] The second button component Figures 7 to 10 , and are arranged as follows.

[0084] The second button assembly 50 comprises a button 51 having a depressible surface 52, which is circular in this example. The button 51 may be formed from a single sheet of material.

[0085] The second button assembly 50 includes an upper housing member 54 and a lower housing member 55 attached together to form a housing that contains the other components of the second button assembly 50. The upper housing member 54 has a hole 56 in which the button 51 is mounted, exposing the depressible surface 52 so that it can be pressed by a user. The second button assembly 50 can be integrated into an electronic device.

[0086] The second button assembly 50 includes a flexible layer 57 disposed below the button 51. The flexible layer 57 is mounted to the lower housing member 55, and thus the lower housing member 55 serves as a support for the flexible layer 57.

[0087] The flexible layer 57 includes a contact portion 58 disposed below the depressible surface 52 of the button 51. The contact portion 58 is depressible.

[0088] The second button assembly 50 also includes a strain gauge 59 fixed to the contact portion 58 on the underside of the flexible layer 57. The strain gauge 59 includes a thin sheet whose resistance changes as the sheet is strained. Depression of the contact portion 58 can therefore be detected by monitoring the change in resistance of the strain gauge 59. The strain gauge 59 thus acts as a sensor device to sense depression of the contact portion.

[0089] The strain gauge 59 has the advantage of being relatively thin, but any other form of sensor device, such as a switch device, may alternatively be used.

[0090] The second button assembly 50 includes an SMA wire 60. Both ends of the SMA wire 60 are fixed to the flexible layer 57 by curling a curling portion 61 mounted on the flexible layer 57. The flexible layer 57 may be a flexible printed circuit (FPC) carrying conductive traces (not shown) connected to the SMA wire 60 and the strain gauge 59.

[0091] The SMA wire 60 is hooked at an intermediate position around a retaining portion 63 formed on a first stopper element 81 that protrudes downwardly from the button 51, as further described below. Thus, the two portions 64 of the SMA wire 60 extending from the retaining portion 60 extend transversely to the direction of travel of the button 51. Thus, the two portions 64 of the SMA wire 60 act in parallel when they are contracted to drive movement of the button 51 relative to the contact layer 53 in a transverse direction (preferably orthogonal) relative to the direction of travel when the button 51 is pressed.

[0092] Furthermore, the two portions 64 of the SMA wire 60 are located beneath the depressible surface 52 of the button 51 , thereby providing a compact overall arrangement for the actuator.

[0093] The diameter of the SMA wire 60 is selected to provide a desired balance of force, stroke, and efficiency. The SMA wire 60 preferably has a diameter of 100 microns or less, or more preferably has a diameter of 35 microns or less. Although the second button assembly 50 includes a single SMA wire 60, any number of SMA wires may generally be included.

[0094] The coil spring 65 is connected to the button 51 at one end on the side opposite to the SMA wire 60. The coil spring 65 is fixed relative to the contact layer 53 at its other end and is arranged to be in a tensioned state. Therefore, the coil spring 65 serves as an elastic biasing element for elastically biasing the SMA wire 60. In general, any number of springs may be included and / or any other form of elastic bias may be provided, such as a compressed coil spring, a leaf spring and / or a flexure.

[0095] The second button assembly 50 also includes two coil springs 65 and 66, which act as elastic biasing elements to elastically bias the SMA wire 60 as follows. The coil springs 65 and 66 are each located between the two portions 64 of the SMA wire 60 and are therefore located below the depressible surface 52 of the button 51. This provides a compact overall arrangement for biasing. The two coil springs 65 and 66 are located within corresponding holes 67 and 68 in the flexible layer 57.

[0096] The coil springs 65 and 66 engage respective holes 67 and 68 at one end, and engage first stopper element 81 and sliding bearing member 88, respectively, projecting downwardly from the button 51, at the other end, as further described below. In this way, the coil springs 65 and 66 are held compressed between the button 51 and the contact portion 58, thereby providing a resilient biasing force to the SMA wire 60.

[0097] When button 51 is pressed, the movement of button 51 in the lateral direction is used to provide a tactile effect. In particular, this lateral movement brings a tactile sensation to the user, which can be perceived as a change in the resistance against the pressing of button 51, even if the downward movement of button 51 is minimal.

[0098] Fig.12 A control circuit 70 is shown for the second button assembly 50. The control circuit 70 is connected to the strain gauge 59 and detects when the output of the strain gauge 59 indicates that the contact layer 53 has been depressed by pressing the button 51. If desired, further layers of insulator and conductor may be added to form a force sensitive switch.

[0099] The control circuit 70 is also connected to the SMA wire 60 and applies a drive signal thereto. In use, in response to detecting a depression of the button 51 , the control circuit 70 drives the SMA wire 60 to move the button 51 .

[0100] The drive signal resistively heats the SMA wire 60, causing it to contract. Due to the biasing effect of the coil spring 65, when the drive signal ceases, the SMA wire 60 cools, causing it to expand. The resulting movement of the button 51 in the lateral direction can be felt by a user pressing the button 51, thereby providing a tactile effect. The tactile effect is a tactile feeling that the user can feel that the button 51 is being pressed down even if the downward travel is minimal.

[0101] Various forms of drive signals may be used to provide different tactile effects, such as a single pulse to provide a single movement of button 51 , or multiple pulses to provide a vibrating movement of button 51 .

[0102] The second button assembly 50 further comprises a sliding bearing member 80 arranged between the button 51 and the flexible layer 57 as such to carry the button 51 on the contact portion 58 .

[0103] The sliding bearing member 80 protrudes downwardly from the button 51 and may be integrally formed with the button 51. The sliding bearing member 80 is aligned with the geometric center of the depressible surface 52 of the button 51, which helps transfer the force from the button 51 to the contact portion 58. The sliding bearing member 80 is thus located between the two portions 64 of the SMA wire 60, which provides a compact arrangement.

[0104] The sliding bearing member 80 continuously contacts the contact portion 58 and supports the button 51 thereon. Therefore, when the button 51 is pressed, the button 51 does not lose stroke before the contact portion 58 is contacted, and the sliding bearing member 80 immediately presses down the contact portion 58. In addition, when the button 51 is pressed, the sliding bearing member 80 acts as a bearing and carries the movement of the button 51 in the lateral direction driven by the SMA wire 60 without interrupting the contact with the contact portion 58.

[0105] The sliding bearing member 80 may be made of or coated with a low surface energy material, such as polytetrafluoroethylene (PTFE), so that there is a low coefficient of friction between the bearing surfaces.

[0106] Although a single plain bearing member 80 is provided in this example, more generally there may be any number of plain bearing members.

[0107] Although the sliding bearing member 80 acts as a bearing element in the second button assembly 50, it may be replaced by any other form of bearing element providing a bearing function, such as one or more bearing balls.

[0108] The second button assembly 50 also includes a first stopper element 81 and a second stopper element 82, which are configured to reduce the tilt of the button 51 when the button 51 is pressed, as described below.

[0109] from Fig. 9 and Fig.10 As can be clearly seen in FIG. 5 , the first stopper element 81 and the second stopper element 82 protrude downward from the button 51. The first stopper element 81 and the second stopper element 82 may be formed integrally with the button 51.

[0110] The first stopper element 81 and the second stopper element 82 protrude toward the lower housing member 55 through corresponding holes 83 and 84 formed in the flexible layer 57. However, the first stopper element 81 and the second stopper element 82 are spaced apart from the lower housing member 55 by a gap selected to limit the tilting of the button 51 when the button 51 is pressed by a user.

[0111] The first stopper element 81 and the second stopper element 82 are arranged on opposite sides of the sliding bearing member 80 in the lateral direction along which the relative lateral movement of the button 51 is driven, thereby limiting the tilting of the button 51 in this direction.

[0112] Therefore, the first stopper element 81 and the second stopper element 82 in the second button assembly 50 have a tilt reduction effect similar to the secondary bearing ball 45 and the spring arm 46 in the first button assembly 10. Accordingly, these features can be interchanged in the first button assembly 10 and the second button assembly 50.

[0113] The button assemblies described herein can be modified to make them waterproof. For example, when the button assembly is arranged in a housing and / or integrated into an electronic device, the depressible surface is exposed so that it can be pressed by a user. However, this may result in a small gap between the depressible surface and the housing or casing of the electronic device. The gap can be filled with a sealant, which can prevent liquid from entering the housing / casing. Additionally or alternatively, the SMA wire can be coated with an insulating material. The ends of the curled SMA wire can be coated with a sealant. The coating can be a conformal insulating coating, such as polyparaxylene. If the SMA wire is coated, but the gap is not sealed, liquid may be able to enter the button assembly, but the conformal coating can prevent the liquid from flowing further into the housing / casing.

[0114] Those skilled in the art will recognize that, although the foregoing has described what is considered to be the best mode and other modes of carrying out the present technology where appropriate, the present technology should not be limited to the specific configurations and methods disclosed in this description of the preferred embodiments. Those skilled in the art will recognize that the present technology has a wide range of applications, and that the embodiments may employ a wide range of modifications without departing from any creative concept as defined in the appended claims.

Claims

1. A button assembly, comprising: a button having a depressible surface; a contact portion, which is below the button, the contact portion being depressible; a sensor device arranged to sense depression of the contact portion; a shape memory alloy actuator arranged to drive movement of the button relative to the contact portion in a lateral direction relative to a direction of travel when the button is pressed; as well as At least one main bearing element is arranged to contact and depress the contact portion when the button is pressed, and to carry the movement of the button in the lateral direction without interrupting the contact with the contact portion when the button is pressed.

2. The button assembly according to claim 1, wherein: The at least one main bearing member continuously contacts the contact portion and supports the button thereon.

3. The button assembly according to claim 1 or 2, wherein: The at least one primary bearing element is aligned with a geometric center of the depressible surface.

4. The button assembly according to claim 1 or 2, wherein: The at least one primary bearing element includes a plurality of bearing elements arranged along a centerline aligned with a geometric center of the depressible surface.

5. The button assembly according to claim 1 or 2, wherein: The button assembly also includes: a support member on which the contact portion is mounted; and At least one stopper element protrudes from the button, the at least one stopper element being spaced apart from the support by a gap that limits the tilting of the button.

6. The button assembly according to claim 5, wherein: The at least one stopper element comprises stopper elements arranged on opposite sides of the at least one main bearing element.

7. The button assembly according to claim 6, wherein: The stopper elements are arranged on opposite sides of the at least one main bearing element in the transverse direction, and the shape memory alloy actuator is arranged to drive the movement of the button in the transverse direction.

8. The button assembly according to any one of claims 1 to 2, 6 to 7, wherein: The button assembly also includes: at least one elastic element arranged laterally beside the main bearing element; and At least one secondary bearing element is in contact with the elastic element and supports the button thereon, the elastic element is arranged to accommodate the stroke of the button, and the at least one secondary bearing element is arranged to carry the movement of the button in the lateral direction to reduce the tilt of the button.

9. The button assembly according to claim 8, wherein: The at least one secondary bearing element includes secondary bearing elements disposed on opposite sides of the at least one primary bearing element.

10. The button assembly according to claim 9, wherein: The secondary bearing elements are arranged on opposite sides of the at least one primary bearing element in a lateral direction, and the shape memory alloy actuator is arranged to drive the movement of the button in the lateral direction.

11. The button assembly according to any one of claims 1 to 2, 6 to 7 and 9 to 10, wherein: The shape memory alloy actuator includes at least one shape memory alloy wire.

12. The button assembly according to claim 11, wherein: The diameter of the shape memory alloy wire is 100 micrometers or less.

13. The button assembly according to claim 11, wherein: Both ends of the shape memory alloy wire are fixed relative to the contact portion, and the shape memory alloy wire is hooked around a retaining portion formed on the button at a middle position, so that the two parts of the shape memory alloy wire extending from the retaining portion are arranged to drive the movement of the button in the lateral direction in parallel.

14. The button assembly according to claim 13, wherein: The at least one main bearing is located between two portions of the shape memory alloy wire extending from the retaining portion.

15. The button assembly according to claim 13 or 14, wherein: Two portions of the shape memory alloy wire extending from the retaining portion are located below the depressible surface of the button.

16. The button assembly according to claim 13 or 14 further comprises at least one elastic biasing element, wherein the at least one elastic biasing element is arranged to elastically bias the shape memory alloy actuator, wherein the at least one elastic biasing element is located between two portions of the shape memory alloy wire extending from the retaining portion.

17. The button assembly according to any one of claims 1 to 2, 6 to 7, 9 to 10 and 12 to 14, further comprising at least one elastic biasing element arranged to elastically bias the shape memory alloy actuator.

18. The button assembly according to any one of claims 1 to 2, 6 to 7, 9 to 10 and 12 to 14, wherein: The or each bearing element is a ball bearing.

19. The button assembly according to any one of claims 1 to 2, 6 to 7, 9 to 10 and 12 to 14, wherein: The or each bearing element is a sliding bearing member protruding from the button.

20. The button assembly according to any one of claims 1 to 2, 6 to 7, 9 to 10 and 12 to 14, wherein: The contact portion comprises a first switching element, and the sensor device comprises a second switching element arranged such that depression of the contact portion causes the switching element to make electrical contact.

21. The button assembly according to any one of claims 1 to 2, 6 to 7, 9 to 10 and 12 to 14, wherein: The sensor device comprises a strain gauge.

22. The button assembly according to claim 21, wherein: The strain gauge is fixed to the contact portion.

23. The button assembly according to claim 21, wherein: The strain gauge includes a thin sheet whose electrical resistance varies with strain of the sheet.

24. A method for delivering a tactile sensation using a button assembly according to any one of claims 1 to 23, the method comprising: sensing depression of the contact portion; as well as A driving signal is applied to the shape memory alloy actuator to drive movement of the button relative to the contact portion.

25. The method according to claim 24, further comprising: Prior to applying the drive signal, a drive signal is selected from a set of drive signals, wherein each drive signal provides a specific haptic effect.

26. A non-transitory data carrier carrying processor control code for implementing the method according to any one of claims 24 and 25.

27. A circuit for delivering a tactile sensation using a button assembly according to any one of claims 1 to 23, the circuit comprising: A detection module, which is used to sense the downward pressure of the contact portion; as well as A driving module is used for applying a driving signal to the shape memory alloy actuator to drive the button to move relative to the contact portion.

28. The circuit of claim 27, wherein: Prior to applying the drive signal, the drive module selects a drive signal from a group of drive signals, wherein each drive signal provides a specific haptic effect.

Images