PATENT DOCUMENT

Publication Number: US-10185397-B2
Application Number: US-201514847114-A
Country: US
Kind Code: B2

Title: Gap sensor for haptic feedback assembly

Abstract:
An electromagnetic actuator provides haptic feedback in a computing device. The electromagnetic actuator includes an actuator gap between the moveable actuator plate and the actuator. A gap sensor measures the actuation gap between the force plate and the actuator. The gap distance between the moveable actuator plate and the actuator may vary due to various environmental or user factors. The amount of haptic feedback provided to a user may be made consistent by adjusting the force exerted by the actuator on the actuator plate in response to measured variations in the gap distance.

Claims:
What is claimed is: 
     
       1. A portable electronic device comprising:
 a housing; 
 a touch assembly associated with the housing and configured to detect a user interaction with the portable electronic device; 
 a first actuator plate assembly associated with the touch assembly; 
 a first actuator separated from the first actuator plate assembly by a first gap, the first gap having a variable dimension parallel to a touch surface of the touch assembly; and 
 a first sensor configured to measure a change in the first gap due to the user interaction with the touch assembly; 
 wherein, 
 an electromagnetic signal is generated by the first actuator as a function of the measured change in the first gap; 
 the electromagnetic signal provides an actuation force to the first actuator plate assembly; and 
 the actuation force provided to the first actuator plate assembly provides haptic output to a user through the first actuator plate assembly and the touch assembly; and 
 the provided haptic output is consistent across different measured changes in the first gap. 
 
     
     
       2. The portable electronic device of  claim 1  wherein the first sensor is a capacitive sensor. 
     
     
       3. The portable electronic device of  claim 2  wherein the capacitive sensor is a parallel plate sensor. 
     
     
       4. The portable electronic device of  claim 2  wherein the capacitive sensor is a comb finger sensor. 
     
     
       5. The portable electronic device of  claim 1  wherein the first sensor is an eddy current sensor. 
     
     
       6. The portable electronic device of  claim 1  wherein the first sensor is an optical sensor. 
     
     
       7. The portable electronic device of  claim 1  wherein the user interaction with the portable electronic device comprises at least one of a touch, a touch location, or a force. 
     
     
       8. The portable electronic device of  claim 7 , wherein movement of the first actuator plate assembly provides an acknowledgement of the user interaction. 
     
     
       9. The portable electronic device of  claim 1  further comprising:
 a second actuator plate assembly associated with the touch assembly; 
 a second actuator separated from the second actuator plate assembly by a second gap; and 
 a second sensor associated with the second actuator plate assembly to measure a change in the second gap. 
 
     
     
       10. The portable electronic device of  claim 1  further comprising:
 a controller configured to communicate with the sensor and the actuator. 
 
     
     
       11. The portable electronic device of  claim 10  wherein the controller is configured to cause the actuator to supply the electromagnetic input to the actuator plate assembly. 
     
     
       12. The portable electronic device of  claim 1  wherein the controller is configured to cause the actuator to supply the electromagnetic input to the actuator plate assembly when the user interaction is determined to correlate with a specific application or a specific user interface element. 
     
     
       13. A method for generating haptic feedback on a trackpad comprising the steps of:
 sensing a user touch on the trackpad; 
 determining an amount of force generated by the sensed user touch and a location of the sensed user touch; 
 measuring, during the sensed user touch, a change in a first actuation gap between a first actuator and a first actuator plate associated with the trackpad, the first actuation gap having a variable dimension parallel to a touch surface of the trackpad; 
 generating, by the first actuator, an electromagnetic signal that is a function of the measured change in the first actuation gap; and 
 electromagnetic input by the first actuator to the first actuator plate based on the measured change in the first actuation gap; wherein, 
 the electromagnetic signal provides an actuation force to the first actuator plate; 
 the actuation force provided to the first actuator plate provides haptic output to a user through the first actuator plate and the trackpad; and 
 the provided haptic output is consistent across different measured changes in the first actuation gap. 
 
     
     
       14. The method of  claim 13  wherein the step of measuring includes capacitively measuring the first actuation gap. 
     
     
       15. The method of  claim 13  wherein the step of measuring includes optically measuring the first actuation gap. 
     
     
       16. The method of  claim 13  wherein the step of measuring includes measuring an eddy current in the first actuator plate. 
     
     
       17. The method of  claim 13  further including the step of measuring a second actuation gap between a second actuator and a second actuator plate associated with the trackpad. 
     
     
       18. The method of  claim 17  further including using the second actuator and the second actuator plate to prevent contact of the trackpad with a housing of a portable electronic device. 
     
     
       19. The method of  claim 13  further comprising:
 determining the location of the user touch correlates with a user interface element selection; and 
 determining the force exceeds a threshold; wherein, 
 the electromagnetic input is further applied to the actuator based on the location determination and the force determination.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 62/129,896, filed Mar. 8, 2015, entitled “Gap Sensor for Haptic Feedback Assembly,” the disclosure of which is hereby incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The present disclosure generally relates to an electromagnetic actuator for providing haptic feedback in a computing device. More particularly, the disclosure relates to compensating for variations in the gap distance between the movable haptic output element and an actuator. 
     BACKGROUND 
     “Haptics” is a tactile feedback technology that simulates the sense of touch by conveying forces, vibrations or other motions to a person. The stimulation caused by various forms of motions may be used to provide tactile feedback in response to an input command or system state. Computers or other portable electronic devices may incorporate haptic actuators that generate these forces or motions to provide sensory feedback or acknowledgement to the user in response to some action taken, or direction given, by that user to the portable electronic device. For example, an input command generated by the user, a device operating state, in response to software executing on the device, and so on may be acknowledged by haptic output. 
     One example of a haptic actuator provides mechanical motion in response to an electrical stimulus. Some haptic feedback mechanisms use electro-mechanical technologies, such as vibratory motors, in which a central mass is moved to create vibrations at a resonant frequency. Other haptic feedback mechanisms use force generating devices attached to a touchpad or touchscreen to generate movement which may be sensed by a user. The quality of the haptic feedback may depend upon various manufacturing tolerances between the haptic feedback mechanism and the touchscreen. 
     SUMMARY 
     Tactile feedback may be provided using an actuator connected to a touchpad on a portable electronic device. The actuator may be controlled by actuator drive signals. As a user of an electronic device interacts with the touch pad, the user may make gestures and perform other touch-related tasks. When the user desires to select an on-screen object or perform other tasks of the type traditionally associated with button or keypad actuation events, the user may press downwards against the surface of the track pad. When sufficient force is detected, appropriate action may be taken and drive signals may be applied to the actuator. Other embodiments may use the direction of motion of a user&#39;s finger or other portion of the user&#39;s body along the touchpad to generate signals to the portable electronic device. 
     The actuator may be used to generate haptic feedback to acknowledge the user&#39;s movement and signal the user that his or her intended instruction has been received. Haptic technology can be applied to various input devices to improve human-computer interaction. For example, a trackpad or touch display can provide tactile feedback, such as a click or vibration, to the user by actuating the touch surface for predetermined displacements. The quality of the haptic feedback provided by the actuator may be deleteriously affected by various environmental factors or user misuse of the portable electronic device. For example, dropping the portable electronic device may affect certain preset manufacturing tolerances. 
     Haptic feedback devices typically have a mechanical gap between the movable plate and actuator/enclosure. This gap is carefully designed to provide enough travel distance to the movable plate while minimizing the adverse effect on the cosmetic appearance of the portable electronic device. Because the actuation force of some haptic actuators (ex. resistance actuator, electrostatic actuator) is a function of the gap between the movable part and actuator, the actuation force is calibrated during manufacture for a given actuation gap. However, this actuation gap can change during the usage of the haptic input devices. For example, the actuation gap might be changed due to mechanical shock in a drop event or due to the relaxation/deformation of the materials. The gap might be changed due to the user input. For example, in a trackpad, the drag motion by the user while exerting force on the trackpad may change the gap during the operation. The change of the actuation gap may result in inconsistent tactile feedback to the user. In a worst case scenario, the actuation force increases too much due to the smaller gap and the movable surface hits the actuator (or enclosure) which may cause damage to the device or generate unwanted acoustic noise. 
     Some prior devices control the haptic system by measuring the motion of the movable plate using a sensor such as an accelerometer. This method requires the actuation of the movable plate to obtain feedback information for the next actuation, and it does not work if the gap is dynamically changed by pressure exerted on the trackpad by the user during movement of the user&#39;s finger. 
     In one embodiment, the disclosed method uses an integrated sensor to measure the gap between the actuator and actuation plates (or trackpad&#39;s enclosure). The gap or gap change can be measured by capacitive, inductive, optical, or thermal sensors. The haptic system controls the actuation force based on the known transfer function calibrated in the factory during manufacture and the measured gap size to provide consistent tactile feedback to the user. In another embodiment, the mechanical design of the gap sensor integrated into the haptic system is disclosed. In yet another embodiment, a method for manufacturing a haptic system including a gap sensor is disclosed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an electronic device including a trackpad; 
         FIG. 2  is a block diagram illustrating a computer system; 
         FIG. 3  is a perspective view showing an input/output device which includes touch sensitive surface and an input actuator; 
         FIG. 4  is a bottom plan view of the input/output device of  FIG. 3 ; 
         FIG. 5  is a side view of the input output device illustrated in  FIGS. 3 and 4 ; 
         FIG. 6  shows a schematic of the control circuitry for an actuation plate and an actuator; 
         FIG. 7  is a flowchart of a sample method for measuring an input and outputting a haptic effect that is controlled for a gap spacing; 
         FIG. 8  is a top view of an actuator and actuator plate with a flexible circuit attached to the actuation plate; 
         FIG. 8A  is a sectional view through line  8 A- 8 A of  FIG. 8 ; 
         FIG. 8B  is a sectional view through line  8 B- 8 B of  FIG. 8 ; 
         FIG. 9  is a bottom view of a force assembly including a second actuator and second actuator plate positioned adjacent to a first actuator; 
         FIG. 10  is a side view of the embodiment shown in  FIG. 9 ; 
         FIG. 11  shows a parallel plate self-capacitance sensor used to detect a gap distance in one embodiment; 
         FIG. 12  shows a mutual capacitive comb finger type sensor used to detect a gap distance in an alternate embodiment; 
         FIG. 13  shows an eddy current sensor used to detect a gap distance in another embodiment; 
         FIG. 14  shows an optical sensor used to detect a gap distance in another embodiment; and 
         FIG. 15  is a flow chart illustrating a method for manufacturing a trackpad. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure may be understood by reference to the following detailed description, taken in conjunction with the drawings as briefly described above. It is noted that, for purposes of illustrative clarity, certain elements in the drawings may not be drawn to scale. Like reference numerals denote like structure throughout each of the various figures. 
     When a user interacts with a portable electronic device, he or she may be asked to provide certain inputs to the portable electronic device in order for that device to determine the needs and/or wishes of the user. In order to provide the user with tactile feedback to acknowledge and confirm the user input, haptics may be used. For example, a user may want tactile confirmation to acknowledge his or her instructions indicating which of various applications on a touchscreen that the user wishes to access. A user may also be prompted to adjust certain functions of the portable electronic device such as sound, picture quality etc. This may be done by touching an indicator displayed on a touchscreen or using a trackpad to move indicia on a screen. In some applications on a portable electronic device, a user may be prompted to select numbers or letters on a touchscreen to provide specific input to the portable electronic device. For example a user may spell a word or complete a form by entering a mark in a certain location. In all of the above situations, a user wants to ensure that the appropriate instruction that represents his or her true intention is selected. In order to satisfy this need for confirmation, the user may desire physical acknowledgement of this touch. 
     Physical confirmation could be made in a visual acknowledgement on a display by the portable electronic device which may confirm that the user instructions have been received. However, in some embodiments, the user may wish to receive physical acknowledgement in the form of haptic feedback from the portable electronic device that his or her commands or inputs have been received. This feedback may be made in the form of tactile feedback by applying forces, vibrations or motions to a finger or fingers of a user which may be in contact with the device during the input operation. In order to provide this haptic feedback, some portable electronic devices may incorporate actuators that apply forces or motion to a trackpad or touchscreen associated with the device which motion is sensed by a user as an output of the device. 
     Generally, embodiments described herein may take the form of a haptic assembly for providing haptic output to a user. A haptic actuator may provide the haptic output in response to an input signal or an output signal, or as part of an output signal. The actuator may vary its output in order to shape and control the haptic response and thus the sensation experienced by a user. In some embodiments, the actuator may be electromagnetically controlled. Embodiments described herein may be incorporated into a variety of electronic or electrical devices, such as a track pad, mouse, or other input (or output) device. The haptic device may be incorporated into an electronic device such as a laptop computer, smart phone, digital music player, tablet computing devices, portable computing devices, feedback or outputs for appliances, automobiles, touchscreens, and the like. 
     Haptic feedback in a portable electronic device may be provided by an actuator which electromagnetically interacts with an actuator plate which is separated from the actuator by a gap distance. Maintaining this gap distance is important to the operation of the haptic input device because the quality of the haptic feedback is dependent thereon. In some situations, a decrease in the gap distance could result in the actuator contacting the actuator plate and/or the contacting the portable electronic device itself. The gap may be set to an optimal distance during manufacture of the portable electronic device but it may change during use due to various factors such as from mechanical shock to the device due to dropping, environmental factors, or normal wear and tear on the device. Thus, by sensing the actual gap distance, the portable electronic device may compensate for any altered gap distance as will be described herein with respect to various embodiments. Even with an altered gap distance the portable electronic device will accept user input. However, the haptic feedback given as a result of those inputs may be deleteriously affected by an altered gap distance. 
     Referring to  FIG. 1 , a portable electronic device  11  which may be a laptop computer system typically includes a display  12  mounted on a housing  13 . Display  12  may provide an image or video output for the electronic device  11 . Display  12  may be substantially any size and may be positioned substantially anywhere on the electronic device  11 . In some embodiments, the display  12  may be a liquid crystal display screen, plasma screen, light emitting diode screen, and so on. The display  12  may also function as an input device in addition to displaying output from the electronic device  12 . For example, display  12  may include capacitive touch sensors, infrared touch sensors, or the like that may capture a user&#39;s input to the display  12 . In these embodiments, a user may press on the display  12  in order to provide input to the electronic device  11 . In alternate embodiments display  12  may be separate from, or otherwise external to, the electronic device  11 , but may be in communication therewith to accept user inputs and provide a visual output for electronic device  11 . 
     Referring again to  FIG. 1 , portable electronic device  11  may further include user interfaces such as a keyboard  14  and a trackpad  15  to allow a user to provide input to computer system  11 . In other embodiments one type of input may be input force from a user&#39;s finger  16  on touch pad  15 . The user may desire to receive feedback from the portable electronic device to confirm the user&#39;s selection on the touchpad. This feedback may take the form of haptic feedback which may also be combined with visual feedback on display  12 . 
       FIG. 2  is a schematic illustrating a sample electronic device  11  including a haptic device in accordance with one embodiment. The device  11  includes a processing unit  17 , a controller  18 , and a trackpad  15  or other input mechanism. Controller  18  and/or processor  17  may execute instructions and carry out operations associated with portable electronic devices as are described herein. While computer system includes a processor  17  and controller  18 , in some embodiments the functions of controller  18 , as described herein, may be implemented by processing unit  17  and controller  18  may be omitted. Using instructions from device memory, controller  18  may regulate the reception and manipulation of input and output data between components of electronic device  11 . Controller  18  may be implemented as one or more microprocessors, application specific integrated circuits (ASICs) and so forth. Controller  18  together with an operating system may execute computer code and manipulate data. The operating system may be a well-known system such as iOS, Windows, Unix or a special purpose operating system or other systems. Controller  18  may include memory or other storage devices to store the operating system and data. Controller  18  may also include application software to implement various functions associated with portable electronic device  11 . 
     Input mechanism  15  may include a trackpad or other input device and, in some embodiments, may include at least one position sensor  19  and/or at least one touch sensor  21  and/or at least one force sensor  22 , as well as one or more actuators  23  and/or an actuator plate  24 . Touch sensor  21  may, in some embodiments be a touch switch. Touch switch may include capacitive, resistive or optical sensors or any other suitable sensor. Further, if the touch sensor is capacitive, it may include self-capacitive or mutual-capacitive sensors. 
     Each of the touch sensor(s)  21 , the position sensor(s)  19 , the force sensor(s)  22  and actuator  23  are electrically and/or mechanically coupled to the trackpad  15 , controller  18  and/or processing unit  17 . Touch sensors  21  may determine the location of one or more touches by a user on the haptic device. The touch sensor(s)  21  and the force sensor(s)  22  detect the location and force of a touch on the trackpad  15  respectively and send corresponding signals to the controller  18 . Actuator  23  may be in communication with controller  18  and/or the input sensors and may generate an electromagnetic signal to actuator plate  24  affixed to trackpad  15  which may provide movement to all or a portion of the surface of trackpad  15  in response to the signal from controller  18 . That is, the input signals which are sensed by one of sensors  19 ,  21  an/or  22  are sent to controller  18  which, in turn, directs actuator  23  to generate an electromagnetic signal which will cause actuator plate  24  to move toward or away from actuator  23  depending upon the signal. As actuator plate  24  is affixed to trackpad  15 , movement of actuator plate  24  will result in movement of trackpad  15 . The haptic output is then based upon the one or more input signals from sensors  19  and/or  21  and/or  22  sent to controller  18 . 
     Some embodiments described herein may take the form of a haptic device for use with an associated electronic device such as computer system  11 . The haptic device may vary output provided to the user through a touchpad or other device on computer  11  based on a number of different inputs to the haptic device. Additionally, the haptic device may vary one or more inputs provided to the computer device  11  based on the user inputs. Inputs to computer device  11  may include a processor or device command based on a system state, application activity, sensor data, and so on. Thus, the haptic device may adapt the output, as well as the types of input provided to computer  11  by the haptic device, based on one or more characteristics, settings, or inputs in a particular application. 
     As another example, the haptic device may provide varying feedback depending on the particular application running on the electronic device, the force input member (e.g., index finger, thumb or palm of the user used to provide input), the amount of input force, the speed and/or acceleration of the input force, the length of time of an input force, location of the electronic device, and/or various other types of data inputs that may be provided to the haptic device, to the electronic device, or a combination of both. It should be noted that the data inputs to vary the output of the haptic device may be provided by a user, the haptic device, and/or the electronic device  11 . 
     When using trackpad  15  to provide input to the computer system  11 , a user may move his or her finger  16  on trackpad  15  to a desired location. The user may also touch trackpad  15  at a desired location to provide input. Touch sensor(s)  21  and the force sensor(s)  22  detect the location and force of the touch on trackpad  15  respectively and send corresponding signals to the controller  18 . Controller  18  communicates with processing unit  17  inside computer system  11  and processing unit  17  may generally instruct controller  18  with respect to certain operations. For example, in one embodiment, processing unit  17  and controller  18 , in combination, use these signals to determine if the location of the touch correlates with a specific application or a user interface (UI) element. If the location is within the range for the specific application or UI element, processing unit  17  further determines if the force signal is above a threshold. If so, processor  17  may validate the force signal as a selection of the application of UI element. If the force signal is not a false signal, then controller  18  activates actuator  23  which combines with actuator plate  24  to move the surface of the trackpad  15  beneath user&#39;s finger  16 . The user may sense this motion, thereby experiencing haptic feedback in response to the application or UI element selection. 
     In another embodiment, track pad  15  may detect user input, such as user touch or user force. In this embodiment, substantially any type of user input detected may be used to provide feedback to the user. Based on the user input, track pad  15  may be activated by the processor  17  to move or vibrate in order to provide haptic feedback to a user. In some instances, the user input may be correlated to a specific application or UI element, in which case the location of the user input may be analyzed to determine if output to the user is desired. In other embodiments, the mere detection of a user input may be sufficient to initiate haptic feedback. It should be noted that haptic feedback may be provided in response not only to a user input, an example of which is provided above, but also in response to system operation, software status, a lack of user input, passage of user input over UI elements(s) (e.g. dragging a cursor over a window, icon, or the like), and/or any other operating condition of computer system  11 . 
     Referring to  FIG. 3 , a perspective view of a track pad  15  is shown. As mentioned above, the quality of the haptic feedback provided to a user may depend upon the quality of the interconnections which couple actuator plate  24  to the user sensing surface such as track pad  15 . Movement of trackpad  15  is accomplished by actuator  23  sending electromagnetic signals to move an actuator plate  24  connected to trackpad  15  to provide vibratory or other motion to trackpad  15 . Trackpad  15  may be moved in the direction of arrows  25  by the combined electromagnetic and mechanical operation of actuator  23  and actuator plate  24 . The association and interconnection of trackpad  15 , actuator  23 , and actuator plate  24  will be described in more detail below with respect to  FIGS. 4-15 . 
     Referring to  FIG. 4 , in one embodiment, a bottom view of a force assembly including trackpad  15 , actuator  23  and actuator plate  24  is shown. The interaction of actuator  23  and actuator plate  24 , as energized through electromagnetic field  26  across an actuation gap  27 , provide the force to trackpad  15 . Electromagnetic signals  26  sent from actuator  23  to plate  24  move plate  24  toward actuator  23  or away from actuator  23  or both (vibratory). This movement may be felt by a user as haptic output on touch pad  15  or other device. 
     Referring to  FIG. 5 , a side view of the embodiment shown in  FIG. 4  is shown. Trackpad  15  may include multiple layers, such as: a gel plate layer (or one or more gel structures) that may provide grounding functions and may operate to restore the actuator plate and/or contact plate to a location after a haptic output is produced; a sensor plate or structure that may sense force and/or touch; and a contact plate for contact by a user. The contact plate may be made from glass or any other suitable material. Movement of user&#39;s finger  16  in the direction of arrow  28  in a drag and click function on trackpad  15  may reduce actuation gap  27  by moving actuation plate  24  (and connected trackpad  15 ) toward actuator  23  due to the force exerted in direction  28  by user finger  16  on trackpad  15 . In one embodiment, the actuation gap set during manufacture may be about 300 microns (0.3 mm). The reduction in actuation gap  27  results in an increase in the actuation force exerted by actuator  23  on actuation plate  24 . Conversely, movement of user finger  16  in the opposite direction to arrow  28  may result in a decrease in actuation force exerted by actuator  23  on plate  24  due to lengthening of gap  27 . This change in actuation force may, over time, result in inconsistent tactile feedback to a user and may even result in actuator plate  24  contacting actuator  23  or other portions of device  11  which may cause damage to the device or generate unwanted acoustic noise. 
     Referring to  FIG. 6 , in one embodiment, actuation gap  27  may be measured using a gap sensor  29  to measure the gap distance  27  between actuator plate  24  and actuator  23 . In one embodiment, sensor  29  may be a capacitive sensor, an inductive sensor, an optical proximity sensor and/or other type of sensor as will be discussed below. Changes in actuation gap  27  may be compensated for by control circuitry including readout circuit  31 , micro controller unit  32  and driver circuit  33 . The actuation force is varied by varying the amount of input current to actuator  23  based upon the sensed actuation gap size  27 . The gap sensor monitors the gap distance in real time and may thus permit the device to compensate for changes in gap distance by changing the input current. The exerted force between actuator  23  and actuator plate  24  varies inversely with the square of actuator gap size  27 . That is, the amount of actuation force exerted by actuator  23  may be varied based upon the transfer function of actuator  23  in combination with the variation in gap  27  due to the force exerted by a user or other conditions such as a dropping event which may change the gap distance  27 . 
     In one embodiment, the measurement of gap  27  may be continuously measured while in another embodiment, gap  27  may be measured only when a user is in contact with trackpad  15 . In the embodiment where gap  27  is continuously measured, electromagnetic interference from the actuator apparatus must be compensated for. In either embodiment, the amount of force exerted by actuator  23  on actuator plate  24  may be varied in real time to compensate for variations in gap  27  such that the haptic output may be perceived by the user as consistent despite variations in user force exerted on trackpad  15  or abnormalities in actuation gap size  27  due to various environmental, user, or misuse (e.g. dropping) conditions. 
     Referring to  FIG. 7 , a flow chart of one embodiment of a method for exerting force on actuation plate  24  is disclosed. In operation  34 , trackpad touch sensor  21  senses a user touch on trackpad  15 . In operation  35 , the amount of force exerted by user  16  may be measured by force sensor  22 . Both operations  34  and  35  are optional and may provide additional input to vary the output of the haptic device. In operation  36 , the actuation gap sensor  29  measures actuation gap  27 . If the measured force on trackpad  15  is determined to be user input, such as a “click” at operation  37 , then the haptic feedback in the form of actuation force may be varied in operation  38  based upon the sensed gap  27 . If the measured force in operation  37  is determined not to be from user input such as a click or tap then the system returns to operation  34  (or  36  if optional operations  34  and  35  are omitted). Based upon the controlled actuation force from operation  38 , a user experiences haptic feedback in operation  39  by movement of actuator plate  24  and the attached trackpad or other surface. Thus, the haptic feedback experienced by the user remains constant even if actuation gap  27  changes due to various environmental, user, or misuse (e.g. dropping) events which could alter the actuation gap and thus increase or decrease the haptic feedback output. 
     Capacitive sensing is based upon capacitive coupling which (in some embodiments) takes human body capacitance as input. There are two types of capacitive sensing systems: mutual capacitance where the finger or other input mechanism alters the mutual coupling between electrodes; and self-capacitance where the object such as a finger or stylus in which a finger or other input mechanism changes an electrode&#39;s capacitance to ground. Either type of capacitive sensor system may be used in various embodiments. 
     Referring to  FIG. 8 , an embodiment using a mutual capacitance sensor is shown. In  FIG. 8  a top view of actuator  23  and actuator plate  24  is shown with flexible circuit  41  attached to actuation plate  24  by pressure sensitive adhesive or other means. An actuation gap  27  which may, in one embodiment, be preset during manufacturing at 0.3 mm (300 microns) separates actuator  23  from actuation plate  24 . Referring to  FIG. 8A , a top view of flexible circuit  41  is shown with sense electrodes  42  and drive electrodes  43  surrounded by ground shield trace  44 . Referring to  FIG. 8B , a cross-sectional view is taken along line  8 B- 8 B from  FIG. 8 . Drive electrode  43  and sense electrode  42  are shown with electromagnetic field  46  generated between actuator  23  and electrodes  42  and  43 . As discussed above, the capacitance between electrodes  42 / 43  and actuator  23  changes depending upon the size of gap  27 . In one embodiment, the input current to actuator  23  is varied to compensate for this change in gap size and thus movement of actuation plate  24  induced by the electromagnetic field  46  generated by actuator  23  is also varied such that the generated movement, as felt by the user, remains consistent despite variations in the size of gap  27 . 
     Referring to  FIG. 9 , an alternate embodiment is shown using multiple actuators and actuator plates. A bottom view of a force assembly including trackpad  15 , actuator  23  and actuator plate  24  is shown with a second actuator  47  and a second actuator plate  48  positioned adjacent to actuator  23 . In this embodiment, actuator  48  and actuator plate  47  have been added to the embodiment shown in  FIG. 6 . The interaction of each actuator  23  and  48  with its corresponding attraction plate  24  and  47  provide the force to trackpad  15  as energized through electromagnetic field  26  and  49  across corresponding actuation gaps  27  and  51 . As with the embodiment shown in  FIG. 6 , gap sensors  29  are used to measure gap distances  27  and  51  and the electromagnetic force  26  may be varied depending upon the changes in gap distances  27  and  51 . This embodiment using multiple actuators and plates allows the apparatus to differentiate movement of user&#39;s finger  16  on trackpad  15  in either direction up  52  or down  53 . 
     Referring again to  FIG. 9 , trackpad  15  is movably placed within housing  54  to allow user  16  to move trackpad  15  within the boundaries of housing  54 . A lower cosmetic gap  55  and an upper cosmetic gap  56  which are nominally the same allow movement of trackpad  15  with respect to housing  54  while preventing trackpad  15  from contacting housing  54  which could damage components and may not be aesthetically satisfactory to user  16 . By measuring an actuator gap in real time and compensating for changes, the movement of trackpad  15  within housing  54  from haptic output may be better controlled thus preventing contact of trackpad  15  with housing  54 . Trackpad  15  may include multiple layers, such as: a gel plate layer (or one or more gel structures) that may provide grounding functions and may operate to restore the actuator plate and/or contact plate to a location after a haptic output is produced; a sensor plate or structure that may sense force and/or touch; and a contact plate for contact by a user. The contact plate may be made from glass or any other suitable material. 
     Referring to  FIG. 10 , a side view of the embodiment shown in  FIG. 9  is illustrated. Movement of user&#39;s finger  16  in the downward direction of arrow  53  in a drag and click function on trackpad  15  reduces actuation gap  27  by moving actuation plate  24  toward actuator  23  due to the force exerted on trackpad  15  by user finger  16 . This same movement and force increases actuation gap  51  between actuator  48  and actuation plate  47 . In one embodiment, the actuation gaps  27  and  51  are set during manufacture to be about 300 microns (3 mm). The reduction in actuation gap  27  results in an increase in the actuation force exerted by actuator  23  and actuation plate  24  and a decrease in actuation force exerted by actuator  48  and actuation plate  47 . Similarly, this movement results in an increase in cosmetic gap  56  and a decrease in cosmetic gap  55 . Movement of user finger  16  in the opposite direction  52  may result in a decrease in actuation force exerted by actuator  23  and actuation plate  24  and an increase in actuation force exerted by actuator  48  and actuation plate  47  and a resultant decrease in cosmetic gap  56  and an increase in cosmetic gap  55 . By measuring the gap distances  27  and  51  in real time and varying actuation force  26 / 49  to compensate for variation in gap distances  27 / 51 , this embodiment may vary the actuator signals to actuator plates to provide consistent haptic feedback experience to a user no matter which direction,  52  or  53 , a user moves his or her finger  16  on trackpad  15 . 
     The embodiment shown in  FIGS. 9 and 10  may utilize the actuator  23  and actuator plate  24  in combination with additional actuator  47  and actuator plate  48  positioned adjacent to actuator  23  to provide restorative force to trackpad  15 . In many devices, gel layers (not shown) between trackpad  15  and housing  54  are typically used to provide such restorative force. For example, in the embodiment shown in  FIG. 10 , if user&#39;s finger  16  moves trackpad  15  in a downward direction  53 , actuator  23  and actuator plate  24  may be used to move trackpad  15  in direction  52  to substantially equalize gaps  27  and  51  and cosmetic gaps  55  and  56  in addition to the restorative force usually provided by gel layer interfaces used to mount trackpad  15  on portable electronic device  11 . 
     Sensor  29 , as discussed above, may be, for example, a parallel plate self-capacitance sensor. Referring to  FIG. 11 , one embodiment using a self-capacitive sensor  29  is shown. As discussed above, this self-capacitive sensor may be attached to actuator plate  24  using adhesive or other means. A voltage differential  57  between actuator plates (stator)  24  and actuator (armature)  23  changes as a function of the change in the actuation gap  27 . That is, the change in capacitance is a function of a change in voltage which is in turn a function of the change in gap distance  27  between actuator  23  and actuator plates  24 . Gap distance  27  is measured in real time as user&#39;s finger  16  moves on trackpad  15  and the change in gap distance  27  is used to alter voltage differential  57  to compensate for changes in the haptic force which would otherwise be exerted by haptic output device due to changing gap distance  27 . By varying the voltage differential as a function of changing gap distance  27  the generated movement of actuation plate  24 , as felt by the user, remains consistent despite variations in the size of gap  27 . 
     Referring to  FIG. 12 , in another embodiment, a sensor (which may be a mutual capacitive comb finger type sensor) is used to sense gap  27 . In this embodiment, actuator  23  includes end portions  58 . As actuator plate  24  moves with respect to actuator  23 , the resulting change in the actuation gap distance  27  results in a change in the capacitance measured between end portions  58  and actuator plate  24 . The change in capacitance is due to the change in surface area  59  of end portions  58  which is adjacent to plate  24 . The change in capacitance is then a function of a change in the distance  27  between actuator  23  and actuator plate  24  respectively. Distance  27  may be measured as user&#39;s finger  16  moves on trackpad  15  and the change in distance  27  is used to modify the haptic force output exerted by haptic feedback device. By varying the electromagnetic force  26  between actuator  23  and actuator plate  24  as a function of changing gap distance  27  the generated movement of actuation plate  24 , as felt by the user, remains consistent despite variations in the size of gap  27 . 
     Referring to  FIG. 13 , in another embodiment, sensor  29  may be an eddy current sensor. Eddy currents are electric currents induced within conductors by a changing magnetic field in the conductor, due to induction. A coil  61 , may measure the amount of eddy current flow. The magnitude of the current in coil loop  61  is proportional to the strength of the magnetic field  26  induced between actuator  23  and actuator plate  24  which is a function of the gap distance  27  and thus eddy current sensor shown in  FIG. 13  may be used to measure the change in gap distance  27 . Distance  27  is measured as user&#39;s finger  16  moves on trackpad  15  and the change in distance  27  is used to compensate for changes in the haptic force exerted by haptic feedback device. The electromagnetic field  26  generated by actuator  23  is also varied as a function of changing gap distance  27  such that the generated movement of actuation plate  24 , as felt by the user, remains consistent despite variations in the size of gap  27 . 
     Referring to  FIG. 14 , an optical sensor which may be a photoelectric sensor  62  may be used as sensor  29 . In this embodiment, optical sensor  62  measures the gap distance  27  between actuator  23  and actuator plate  24 . A light beam  63  is emitted from sensor  62  to actuator plate  24  and reflected back to sensor  62  to measure the distance  27  between actuator plate  24  and actuator  23 . Distance  27  is measured as user&#39;s finger  16  moves on trackpad  15  and the change in distance  27  is used to compensate for changes in the haptic force exerted by haptic feedback device. By varying the electromagnetic force  26  between actuator  23  and actuator plate  24  as a function of changing gap distance  27 , the generated movement of actuation plate  24 , as felt by the user, remains consistent despite variations in the size of gap  27 . 
     Referring to  FIG. 15 , a flow chart illustrating the operations for manufacturing a trackpad including a haptic feedback device is shown. At operation  64 , a gap sensor  29  is connected to an actuator. In operation  65 , an actuator plate is connected to a force assembly. This secure mechanical interconnection between actuator plate and force assembly results in vibrational, lateral, or other movement induced by the actuator being efficiently transferred to the actuator plate and thus to the force assembly. At operation  66 , a device board which may include a controller is securely connected to the actuator to supply and control power to the actuator. The touchpad is associated with the force assembly in operation  67  which may include placement of flexible pads, which may be a foam or gel pad, between the force assembly and the touchpad assembly. The touchpad assembly may include a gel plate layer (or set of gel structures), a sensor plate or other sensor apparatus, and a contact plate or other structure for contact by a user&#39;s person. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20150908
Publication Date: 20190122
Grant Date: 20190122
Priority Date: 20150308
Inventors: YONEOKA, SHINGO
LAM, Chun Chit
MCEUEN, SCOTT J.
Augenbergs, Peteris J.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/016", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0414", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/169", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/03547", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/016", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/016", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/169", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/03547", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/016", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 56849829