PATENT DOCUMENT

Publication Number: US-10222863-B1
Application Number: US-201715695516-A
Country: US
Kind Code: B1

Title: Linear haptic actuator including field members and biasing members and related methods

Abstract:
A linear haptic actuator may include an actuator housing and at least one coil carried by the actuator housing. The linear haptic actuator may also include field members moveable along a path of travel within the actuator housing in response to the at least one coil and a respective end biasing member between each end field member and adjacent portions of the actuator housing. A respective internal biasing member may be between adjacent field members.

Claims:
That which is claimed is: 
     
       1. A linear haptic actuator comprising:
 an actuator housing comprising opposing deformable end walls; 
 at least one coil carried by the actuator housing; 
 a plurality of field members moveable along a path of travel within the actuator housing in response to the at least one coil, the plurality of field members comprising end field members; 
 a respective end spring member between each end field member and adjacent portions of the actuator housing, each end spring member being coupled to a respective opposing deformable end wall and having a spring constant less than or equal to a spring constant of each opposing deformable end wall; and 
 a respective internal spring member between adjacent ones of the plurality of field members. 
 
     
     
       2. The linear haptic actuator of  claim 1  further comprising a controller configured to drive the at least one coil to move the plurality of field members in opposing directions. 
     
     
       3. The linear haptic actuator of  claim 1  further comprising a controller configured to drive the at least one coil to move the plurality of field members in a same direction. 
     
     
       4. The linear haptic actuator of  claim 1  wherein the plurality of field members comprises a pair of field members, each having a same mass. 
     
     
       5. The linear haptic actuator of  claim 1  wherein the end spring members each has a same spring constant. 
     
     
       6. The linear haptic actuator of  claim 1  further comprising a respective limiter adjacent each deformable end wall. 
     
     
       7. The linear haptic actuator of  claim 1  wherein the end spring members have a different spring constant than the at least one internal spring member. 
     
     
       8. An electronic device comprising:
 a device housing; 
 wireless communications circuitry carried by the device housing; 
 a linear haptic actuator carried by the device housing and comprising
 an actuator housing comprising opposing deformable end walls; 
 at least one coil carried by the actuator housing, 
 a plurality of field members moveable along a path of travel within the actuator housing in response to the at least one coil, the plurality of field members comprising end field members, 
 a respective end spring member between each end field member and adjacent portions of the actuator housing, each end spring member being coupled to a respective opposing deformable end wall and having a spring constant less than or equal to a spring constant of each opposing deformable end wall, and 
 a respective internal spring member between adjacent ones of the plurality of field members; and 
 
 a controller configured to cooperate with the wireless communications circuitry and the linear haptic actuator to perform at least one wireless communications function and selectively operate the linear haptic actuator, respectively. 
 
     
     
       9. The electronic device of  claim 8  wherein the controller is configured to drive the at least one coil to move the plurality of field members in opposing directions. 
     
     
       10. The electronic device of  claim 8  wherein the controller is configured to drive the at least one coil to move the plurality of field members in a same direction. 
     
     
       11. The electronic device of  claim 8  wherein the plurality of field members comprises a pair of field members, each having a same mass. 
     
     
       12. The electronic device of  claim 8  wherein the end spring members each has a same spring constant. 
     
     
       13. A method of driving a linear haptic actuator comprising an actuator housing having opposing deformable end walls, at least one coil carried by the actuator housing, a plurality of field members moveable along a path of travel within the actuator housing in response to the at least one coil, the plurality of field members comprising end field members, a respective end spring member between each end field member and adjacent portions of the actuator housing, each end spring member being coupled to respective opposing deformable end walls and having a spring constant less than or equal to a spring constant of each opposing deformable end wall, and a respective internal spring member between adjacent ones of the plurality of field members, the method comprising:
 using a controller to drive the at least one coil to move the plurality of field members in opposing directions. 
 
     
     
       14. The method of  claim 13  further comprising using the controller to drive the at least one coil to move the plurality of field members in a same direction. 
     
     
       15. The method of  claim 13  wherein the plurality of field members comprises a pair of field members, each having a same mass. 
     
     
       16. The method of  claim 13  wherein the end spring members each has a same spring constant.

Description:
TECHNICAL FIELD 
     The present disclosure relates to the field of electronics, and, more particularly, to the field of haptics. 
     BACKGROUND 
     Haptic technology is becoming a more popular way of conveying information to a user. Haptic technology, which may simply be referred to as haptics, is a tactile feedback based technology that stimulates a user&#39;s sense of touch by imparting relative amounts of force to the user. 
     A haptic device or haptic actuator is an example of a device that provides the tactile feedback to the user. In particular, the haptic device or actuator may apply relative amounts of force to a user through actuation of a mass that is part of the haptic device. Through various forms of tactile feedback, for example, generated relatively long and short bursts of force or vibrations, information may be conveyed to the user. 
     SUMMARY 
     A linear haptic actuator may include an actuator housing and at least one coil carried by the actuator housing. The linear haptic actuator may also include a plurality of field members moveable along a path of travel within the actuator housing in response to the at least one coil and a respective end biasing member between each end field member and adjacent portions of the actuator housing. A respective internal biasing member may be between adjacent field members. 
     The linear haptic actuator may further include a controller configured to drive the at least one coil to move the plurality of field members in opposing directions. The linear haptic actuator may include a controller configured to drive the at least one coil to move the plurality of field members in a same direction, for example. 
     The plurality of field members may include a pair of field members, each having a same mass. The end biasing members each may have a same spring constant. 
     The actuator housing may include opposing deformable end walls coupled to respective end biasing members, for example. Each deformable end wall may have a spring constant greater than the spring constant of the end biasing members. 
     The linear haptic actuator may further include a respective limiter adjacent each deformable end wall. The end spring members may have a different spring constant than the at least one internal spring member, for example. 
     A method aspect is directed to a method of driving a linear haptic actuator that includes an actuator housing, at least one coil carried by the actuator housing, a plurality of field members moveable along a path of travel within the actuator housing in response to the at least one coil, a respective end biasing member between each end field member and adjacent portions of the actuator housing, and a respective internal biasing member between adjacent field members. The method may include using a controller to drive the at least one coil to move the plurality of field members in opposing directions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of an electronic device in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of the electronic device of  FIG. 1   
         FIG. 3  is a schematic diagram of the haptic actuator of the electronic device of  FIG. 1 . 
         FIG. 4  is a schematic diagram of a haptic actuator in accordance with another embodiment. 
         FIG. 5  is a schematic diagram illustrating whole device haptic feedback in accordance with an embodiment. 
         FIG. 6  is a schematic diagram illustrating localized haptic feedback in accordance with an embodiment. 
         FIG. 7  is a graph illustrating field member displacement during operation of a haptic actuator in accordance with an embodiment. 
         FIG. 8  is a graph illustrating a difference of displacement between field members in accordance with an embodiment. 
         FIG. 9  is a schematic diagram of a portion of an electronic device and haptic actuator according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout, and prime and multiple prime notation is used to indicate similar elements in alternative embodiments. 
     Referring initially to  FIGS. 1-3 , an electronic device  20  illustratively includes a device housing  21  and a controller  22  carried by the device housing. The electronic device  20  is illustratively a mobile wireless communications device, for example, a mobile telephone. The electronic device  20  may be another type of electronic device, for example, a wearable wireless communications device, and includes a band or strap for securing it to a user, a tablet computer, a laptop computer, etc. 
     Wireless communications circuitry  25  (e.g. cellular, WLAN Bluetooth, etc.) is also carried within the device housing  21  and coupled to the controller  22 . The wireless communications circuitry  25  cooperates with the controller  22  to perform at least one wireless communications function, for example, for voice and/or data. In some embodiments, the electronic device  20  may not include wireless communications circuitry  25 . 
     A display  23  is also carried by the device housing  21  and is coupled to the controller  22 . The display  23  may be a light emitting diode (LED) display, for example, or may be another type of display, for example, a liquid crystal display (LCD) as will be appreciated by those skilled in the art. The display  23  may be a touch display, for example, responsive to user input. 
     A finger-operated user input device  24  illustratively in the form of a pushbutton switch is also carried by the device housing  21  and is coupled to the controller  22 . The pushbutton switch  24  cooperates with the controller  22  to perform a device function in response to operation thereof. For example, a device function may include a powering on or off of the electronic device  20 , initiating communication via the wireless communications circuitry  25 , and/or performing a menu function. In some embodiments, there may not be a discrete finger-operated user input device  24  and/or when the display  23  is in the form of a touch screen display, the display may be a finger-operated input device. 
     The electronic device  20  illustratively includes a linear haptic actuator  40 . The haptic actuator  40  is coupled to the controller  22 , which determines user indications and operates the haptic actuator by way of applying power, current, or a voltage to one or more coils  44  to move a first and second or a pair of field members  50   a ,  50   b  (which also may be referred to as masses) based upon the user indication. More particularly, the haptic actuator  40  cooperates with the controller  22  to provide haptic feedback to the user. The haptic feedback may be in the form of relatively long and short vibrations or “taps”, particularly, for example, when the electronic device  20  is in the form of a wearable device and the user is wearing the electronic device. The vibrations may be indicative of a message received, and the duration of the vibration may be indicative of the type of message received. Of course, the vibrations may be indicative of or convey other types of information. 
     While a controller  22  is described, it should be understood that the controller  22  may include one or more of a processor and other circuitry to perform the functions described herein, and some or all of the circuitry may be carried by an actuator housing and/or by the device housing  21 . 
     Further details of the haptic actuator  40  are now described. The haptic actuator  40  includes an actuator housing  41 . The actuator housing  41  includes deformable end walls  42   a ,  42   b  each having a spring constant associated therewith. The one or more coils  44  are carried by the actuator housing  41 . There may be any number of coils  44  arranged in any number of configurations, as will be appreciated by those skilled in the art. 
     The pair of field members  50   a ,  50   b  are moveable along a path of travel within actuator housing  41  in response to the coil(s)  44 . In some modes of operation, the field members  50   a ,  50   b  are moveable relative to one another. Each of the pair of field members  50   a ,  50   b  have a mass associated therewith and each may include one or more permanent magnets that cooperate with the coil(s)  44  to cause movement along the path of travel. Each of the pair of field members  50   a ,  50   b  may have a same mass, for example, to provide desired haptic feedback as will be described in further detail below. While two field members  50   a ,  50   b  are illustrated, there may be more than two field members, for example, three field members  50   a ′- 50   c ′, as illustrated in  FIG. 4 . 
     Respective end biasing members  51   a ,  51   b  are between each end field member  50   a ,  50   b  and adjacent portions of the actuator housing  41 , and more particularly, coupled to the opposing deformable end walls  42   a ,  42   b . The end biasing members  51   a ,  51   b  have a spring constant associated therewith that is less than the spring constant of the opposing deformable end walls  42   a ,  42   b.    
     In this present example embodiment of two field members  50   a ,  50   b , each field member is an end field member. However, in embodiments where there are more than two field members  50   a ,  50   b , for example, three as illustrated in  FIG. 4 , there will be two end field members  50   a ′,  50   c ′ and an inner field member  50   b ′. Each respective end biasing member  51   a ,  51   b  may be a spring, flexure, or other type of biasing member. Each of the end biasing members  51   a ,  51   b  may have a same spring constant, for example, to achieve desired operation, as will be explained in further detail below. As will be appreciated by those skilled in the art, when a coil spring, for example, is used, the field members  50   a ,  50   b  may be slidably moveable along or carried by a shaft. Alternatively, if a flexure bearing is used, there may be no shaft as the field members  50   a ,  50   b  may be suspended in equilibrium between the flexure bearings. 
     A respective internal biasing member  52  is between adjacent field members  50   a ,  50   b . The internal biasing member  52  also has a spring constant associated therewith that may be different than the spring constants of the respective end biasing members  51   a ,  51   b . In the present example embodiment, since there are two field members  50   a ,  50   b , a single internal biasing member  52  is between the first and second field members  50   a ,  50   b . In embodiments, where there are three field members, for example as illustrated in  FIG. 4 , there are two internal biasing members  52   a ′,  52   b ′ between the first and second field members  50   a ′,  50   b ′ and the second and third field members  50   b ′,  50   c ′. Similarly to the end biasing members  51   a ,  51   b , each internal biasing member  52  may be a spring, flexure, or other type of biasing member. 
     The configuration of the field members  50   a ,  50   b  and end and internal biasing members  51   a ,  51   b ,  52  permit operation thereof in different modes. A first mode may be considered a localized mode whereby haptic feedback may be focused in the area around the haptic actuator  40 , for example where in the device housing  21  the haptic actuator is mounted. A second mode may provide haptic feedback felt throughout the device  20  or the device housing  21 . The second mode may be particularly undesirable for use with relatively lightweight electronic devices, such as, for example, wearable devices, since the user may find it uncomfortable with the entire electronic device vibrating or shaking when the haptic actuator is operated. 
     Referring additionally to  FIGS. 5 and 6 , to provide localized haptic feedback (i.e., the first mode) the controller  22  drives the coils  44  to move the field members  50   a ,  50   b , in opposing directions ( FIG. 6 ). As will be appreciated by those skilled in the art, to provide the localized haptic feedback, no or relatively small net motion is introduced to the electronic device  20 . To provide haptic feedback throughout the device housing  21 , the controller  22  drives the coils  44  to move the field members  50   a ,  50   b  in the same direction ( FIG. 5 ). 
     Advantageously, the haptic actuator  40  may not induce any net shaking motion to the entire electronic device, while providing localized pinpoint haptic feedback where it is mounted to electronic device housing  21  when localized haptic feedback is desired. Moreover, the haptic actuator  40  has a smaller form factor needed than, for example, two separate haptic actuators each operating in the desired mode of operation as an extra housing, mounting location in the device housing, associated electronics, etc. are generally not needed as these are “integrated” with respect to the embodiments of the haptic actuator  40  described herein. 
     Referring particularly to  FIG. 3 , the localized haptics provided by the haptic actuator  40  can be illustrated through a vibration dynamics analysis.  FIG. 3  illustrates the equivalent vibration model for the haptic actuator  40  with the direction of two actuation forces opposite to each other. The first and second field members  50   a ,  50   b  are the same weight, and the spring constants of the end biasing members  51   a ,  51   b  are the same. The controller  22  may drive the coils  44  to move the haptic actuator  40  with any waveform, and the model assumes the boundaries (end walls  42   a ,  42   b ) are solid (i.e., a very large spring constant (k 2 ) compared to the respective end biasing members  51   a ,  51   b ). 
     The governing dynamics equation of the system is:
 
 m×X   {umlaut over (1)}   F   0   +k   1 ×( X   2   −X   1 )− k   2   ×X   1  
 
 m×X   {umlaut over (2)}   −F   0   +k   1 ×( X   1   −X   2 )− k   2   ×X   2  
 
     Through derivation from the differential equations, above, there are two resonance modes: 
     
       
         
           
             
               w 
               1 
             
             = 
             
               
                 
                   k 
                   2 
                 
                 m 
               
             
           
         
       
     
     
       
         
           
             
               w 
               2 
             
             = 
             
               
                 
                   
                     k 
                     2 
                   
                   + 
                   
                     2 
                     × 
                     
                       k 
                       1 
                     
                   
                 
                 m 
               
             
           
         
       
     
     When the two actuation forces are in the same direction, the first and second field members  50   a ,  50   b  travel together in the same direction for the entire duration, an thus acting as a typical haptic actuator (i.e., operating to provide haptic feedback to the entire device housing  21 ), which induces a net vibe motion to the entire device  20 . After the actuation forces are turned off, for example, the first and second field members  50   a ,  50   b  continue to resonate in the same mode with natural frequency=w 1  (referred to as “net resonance”). In contrast, when the two actuation forces F 0  are in opposite directions, the first and second field members  50   a ,  50   b  vibrate in opposite directions under the same displacement/velocity magnitude for the entire duration. After the actuation forces are turned off simultaneously, the first and second field members  50   a ,  50   b  continue to resonate with the second resonance mode=w 2  (referred to as “self-resonance”). In other words, before or after the forces are turned off, there typically is no net vibration to the entire device  20 , but the force exerted by the springs (k 2 ) on each of end wall  42   a ,  42   b  of the actuator housing  41  will be tangible at where it is mounted. Note that as long as the magnitude of the two actuation forces are the same, the system model for the haptic actuator  40  will apply regardless of the F 0  waveform (square, sinusoidal, and etc.). 
     Simulated vibration analysis was performed with respect to the haptic actuator  40  and model illustrated in  FIG. 3 . The graph  60  in  FIG. 7  illustrates displacement from the first and second field members  50   a ,  50   b  when actuated by two equal but opposite actuation forces that lasted from 0-2 seconds, and turned off afterwards. The displacements are the same and opposite to each other during operation, for example, when the controller  22  drives the coil  44  to move the field members  50   a ,  50   b  in opposing directions. It should be noted that the oscillation frequency changed to the natural resonant (self-resonance) frequency after the force is turned off. Accordingly, a user can feel the localized haptic feeling near where the haptic actuator  40  is mounted within the device housing  21 . The graph  61  in  FIG. 8  illustrates no net motion from the difference of displacement between the first and second field members  50   a ,  50   b.    
     Simulation software was used to simulate and confirm that the aforementioned vibration dynamics under the self-resonance mode (direction of two driving force is opposite to each other). Here the weight of both field members  50   a ,  50   b  is 1 gram, k 1 =1000 N/m, and k 2 =200 N/m, and the magnitude of the two actuation forces (sine wave) was F 0 =10N, and its driving frequency was 20 Hz from 0-2 seconds. The force or the driving of the coils  44  to move the first and second field members  50   a ,  50   b  is turned off after 2 seconds. The resulting maximum displacement for the two end biasing members  51   a ,  51   b  mounted at the opposing deformable end walls  42   a ,  42   b  was about ˜5 mm, which translates into ˜1N at each end to a user. 
     As will be appreciated by those skilled in the art, the vibration dynamics may be compromised by the mounting boundary (i.e., end walls). Thus, as noted above, it may be particularly desirable to make the opposing end walls  42   a ,  42   b  of the actuator housing  41  relatively thin or deformable (i.e., not a perfectly rigid boundary) to transfer the pinpoint haptic feeling to the user. 
     The surface of the device housing  21  where the haptic actuator housing  41  is mounted may be flush with the adjacent surface of the device for improved aesthetics. However, during vibration, the respective deformable end wall  42   a ,  42   b  may move inward as a result of the deformable surface design. 
     Referring to  FIG. 9 , another embodiment may address the inward movement of the deformable end wall  42   a ″,  42   b ″. For a pinpoint or localized haptic feedback, total “stress” rather than “force” for which the user&#39;s experience may be dependent. The haptic stress can be maximized by minimizing or reducing the contact area for the user. Accordingly, the spring constant k 2  of the respective end biasing members  51   a ″,  51   b ″ may be relatively small compared to the equivalent spring constant of the deformable end wall  42   a ″, 42   b ″. Thus, a respective limiter  47 ″ adjacent each deformable end wall  42   a ″,  42   b ″ may reduce the area having inward motion, and thus, not visible from the exterior of the device housing  21 ″. 
     A method aspect is directed to a method of driving a linear haptic actuator  40  that includes an actuator housing  41 , at least one coil  44  carried by the actuator housing, a plurality of field members  50   a ,  50   b  moveable along a path of travel within the actuator housing in response to the at least one coil, a respective end biasing member  51   a ,  51   b  between each end field member and adjacent portions of the actuator housing, and a respective internal biasing member  52  between adjacent field members. The method includes using a controller  22  to drive the at least one coil  44  to move the plurality of field members  50   a ,  50   b  in opposing directions. 
     Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.

Metadata:
Filing Date: 20170905
Publication Date: 20190305
Grant Date: 20190305
Priority Date: 20170905
Inventors: SEN, YI-HENG
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F1/1684", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1658", "inventive": true, "first": false, "tree": "[]"}, {"code": "B06B1/14", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/016", "inventive": true, "first": true, "tree": "[]"}, {"code": "B06B1/0207", "inventive": false, "first": false, "tree": "[]"}, {"code": "G08B6/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1626", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/016", "inventive": true, "first": true, "tree": "[]"}, {"code": "B06B1/14", "inventive": false, "first": false, "tree": "[]"}, {"code": "B06B1/0207", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/016", "inventive": true, "first": true, "tree": "[]"}, {"code": "B06B1/14", "inventive": false, "first": false, "tree": "[]"}, {"code": "G08B6/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "B06B1/0207", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/1684", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1658", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1626", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 65495870