PATENT DOCUMENT

Publication Number: US-10642361-B2
Application Number: US-201715797992-A
Country: US
Kind Code: B2

Title: Haptic electromagnetic actuator

Abstract:
A haptic electromagnetic actuator for track pad is provided. The actuator includes an array of electromagnets with alternating South and North poles on a first end, each magnet comprising a metal core and an electrical wire around the metal core. The array of magnets is coupled to a base plate on a second end opposite to the first end. The actuator also includes an attraction plate at a distance from the first end of the array of the magnets such that the attraction plate moves toward the magnets when an electrical current flows through the electrical wire around the metal core and moves away from the magnets when the current becomes zero. The array of magnets is configured to form a uniform gap from the attraction plate.

Claims:
What is claimed is: 
     
       1. A device, comprising:
 a plate defining a haptic output surface on an exterior of the device; 
 an attraction plate attached to a surface of the plate opposite the haptic output surface, the attraction plate extending under the plate; and 
 a haptic electromagnetic actuator extending under the plate and comprising an array of electromagnets positioned along an axis parallel to the haptic output surface; wherein: 
 the array of electromagnets comprises alternating poles along the axis; 
 each electromagnet comprises a metal core and an electrical wire around the metal core; 
 the attraction plate is biased to maintain a gap between the attraction plate and the array of electromagnets; and 
 the array of electromagnets is configured to overcome the bias and move the attraction plate toward the array of electromagnets, in a plane parallel to the plate, when an electrical current flows through each electrical wire around each metal core. 
 
     
     
       2. The device of  claim 1 , wherein the plate comprises a trackpad plate. 
     
     
       3. The device of  claim 2 , further comprising:
 a housing; 
 a set of bending beams coupled to the housing; and 
 a set of gels on the bending beams; wherein: 
 the trackpad plate is positioned on the set of gels and supported by the bending beams. 
 
     
     
       4. The device of  claim 3 , wherein the haptic electromagnetic actuator is coupled to at least one bending beam in the set of bending beams. 
     
     
       5. The device of  claim 1 , wherein a first edge of the attraction plate adjacent the gap is substantially parallel to a second edge of the plate. 
     
     
       6. The device of  claim 1 , wherein each of the electromagnets is coupled to a base plate at a first end. 
     
     
       7. The device of  claim 6 , wherein each of the electromagnets defines a pointed end opposite the first end. 
     
     
       8. The device of  claim 7 , wherein the attraction plate defines a sawtooth shape, the sawtooth shape comprising a plurality of projections. 
     
     
       9. The device of  claim 8 , wherein each of the plurality of projections is received between at least two electromagnets. 
     
     
       10. An input device, comprising:
 a plate defining a plane; 
 an attraction plate coupled to the plate, the attraction plate extending under the plate; 
 an actuator operatively connected to the attraction plate and extending under the plate, the actuator comprising an array of solid core electromagnets arranged linearly on an axis parallel to the plane, with pole faces of each electromagnet in the array of electromagnets oriented to face the attraction plate; 
 a force sensor operatively connected to the plate; 
 a touch sensor operatively connected to the plate; and 
 a controller operatively connected to at least one of the touch sensor, the actuator, and the force sensor; wherein 
 the controller is configured to actuate the actuator, causing movement of the attraction plate and the plate to provide a haptic feedback at the plate in response to an input to the force sensor. 
 
     
     
       11. The input device of  claim 10 , wherein the plate is a track pad plate. 
     
     
       12. The input device of  claim 10 , further comprising:
 a position sensor operatively connected to the plate; wherein 
 the position sensor is operative to detect a motion of the plate. 
 
     
     
       13. The input device of  claim 12 , wherein the controller is operative to actuate the plate to provide the haptic feedback in response to a signal from the controller. 
     
     
       14. The input device of  claim 12 , wherein the position sensor is operative to detect a motion of the plate relative to the actuator. 
     
     
       15. The input device of  claim 12 , wherein the position sensor comprises an accelerometer. 
     
     
       16. The input device of  claim 10 , wherein the force sensor is operative to determine an approximate force exerted on the plate. 
     
     
       17. The input device of  claim 16 , wherein the touch sensor is operative to determine a location at which a touch is present on the plate. 
     
     
       18. The input device of  claim 17 , wherein the controller is operative to correlate the approximate force with the location. 
     
     
       19. The input device of  claim 10 , wherein the plate moves in-plane when moved by the actuator. 
     
     
       20. The input device of  claim 19 , wherein the plate moves laterally with respect to the actuator.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a divisional of U.S. patent application Ser. No. 14/404,156, filed Nov. 26, 2014, entitled “Haptic Electromagnetic Actuator,” which is a 35 U.S.C. 371 application of PCT/US2013/045011, filed Jun. 10, 2013, entitled “Haptic Electromagnetic Actuator,” which claims the benefit of U.S. Provisional Application No. 61/658,764, filed Jun. 12, 2012, entitled “Haptic Electromagnetic Actuator,” and U.S. Provisional Application No. 61/800,092, filed Mar. 15, 2013, entitled “Haptic Electromagnetic Actuator,” the contents of which are incorporated by reference as if fully disclosed herein. 
    
    
     TECHNICAL FIELD 
     The present invention generally relates to an electromagnetic actuator for providing haptic feedback in a computing device, and more particularly to an electromagnetic actuator generating linear motion parallel to an input surface. 
     BACKGROUND 
     Haptics is a tactile feedback technology which pertains to the sense of touch by applying forces, vibrations or motions to a user. This mechanical stimulation may be used to provide tactile feedback in response to an input command or system state. Haptic devices may incorporate actuators that apply forces or motion to the skin for providing touch feedback. One example of a haptic actuator provides mechanical motion in response to an electrical stimulus. Most haptic feedback mechanisms use mechanical technologies such as vibratory motors, like a vibrating alert in a cell phone, in which a central mass is moved to create vibrations at a resonant frequency. The kinetic energy of these vibrations may be sensed by a user. These motors provide strong feedback, but produce a limited range of sensations. 
     There remains a need for developing actuators with flat shape, but sufficient travel distance or working distance and sufficient force and fast response. 
     SUMMARY 
     Embodiments described herein may provide a flat actuator which generates relatively large travel distance and high magnetic force. The disclosure provides methods for fabricating the actuator from a flat laminated metal sheet. Such fabrication methods may be cost effective and may provide the dimensional precision as needed. 
     In an embodiment, a haptic electromagnetic actuator for trackpad is provided. The actuator includes an array of electromagnets with alternating South and North poles on a first end, each magnet comprising a metal core and an electrical wire around the metal core. The array of magnets is coupled to a base plate on a second end opposite to the first end. The actuator also includes an attraction plate at a distance from the first end of the array of the magnets such that the attraction plate moves toward the magnets when an electrical current flows through the electrical wire around the metal core and moves away from the magnets when the current becomes zero. The array of magnets is configured to form a uniform gap from the attraction plate. 
     In another embodiment, a track pad is provided to include a haptic electromagnetic actuator. The track pad includes a housing, and a track plate coupled to the housing by bending beams. The track pad also includes an actuator having a baseplate coupled to the housing on a first end. The baseplate supports an array of electromagnets with alternating South and North poles on a second end opposite to the first end. The actuator has an attraction plate coupled to the track plate. 
     In a further embodiment, a method is provided for fabricating an actuator. The method includes providing a laminated sheet metal and stamping the sheet metal to an array of metal cores with a support base. The method also includes annealing the sheet metal. The method further includes placing electrical wires around the metal cores, and soldering two ends of each wire to the support base. 
     Additional embodiments and features are set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the specification or may be learned by the practice of the invention. A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings, which forms a part of this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a computer system in an embodiment. 
         FIG. 2A  illustrates a bottom view of a trackpad with an electromagnetic actuator in an embodiment. 
         FIG. 2B  illustrates a bottom view of a trackpad with an electromagnetic actuator in another embodiment. 
         FIG. 3A  illustrates a side view of the electromagnetic actuator in an embodiment. 
         FIG. 3B  illustrates a top view of the electromagnetic actuator of  FIG. 3A . 
         FIG. 4A  illustrates a side view of the electromagnetic actuator in another embodiment. 
         FIG. 4B  illustrates a top view of the electromagnetic actuator of  FIG. 4A . 
         FIG. 4C  is a perspective view of the actuator of  FIGS. 4A and 4B . 
         FIG. 5A  illustrates a side view of the electromagnetic actuator in an alternative embodiment. 
         FIG. 5B  illustrates a side view of the electromagnetic actuator of  FIG. 5A . 
         FIG. 6A  illustrates a side view of the electromagnetic actuator in a further embodiment. 
         FIG. 6B  illustrates a top view of the electromagnetic actuator of  FIG. 6A . 
         FIG. 7  illustrates simulated magnetic flux field for actuator of  FIGS. 3A and 3B  in an embodiment. 
         FIG. 8  illustrates simulated magnetic flux field for actuator of  FIGS. 4A and 4B  in an embodiment. 
         FIG. 9  is a flow chart illustrating steps for fabricating the actuator in an embodiment. 
         FIG. 10  illustrates a comparison of displacement versus gap for annealed and non-annealed actuators in an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure may be understood by reference to the following detailed description, taken in conjunction with the drawings as briefly described below. It is noted that, for purposes of illustrative clarity, certain elements in the drawings may not be drawn to scale. 
     Generally, embodiments described herein may take the form of an actuator for providing a haptic output to a surface. The 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. Embodiments may likewise be incorporated into a variety of different electronic devices, including smart phones, tablet computing devices, portable computing devices, feedback or outputs for appliances, automobiles, and the like, touchscreens, and so on. 
       FIG. 1  illustrates a computer system in accordance with a sample embodiment. The computer system  100  includes a processing unit  118 , a micro controller  102 , and a trackpad  114 . As shown in  FIG. 1 , the computer system includes a processing unit  118  and a microcontroller  102 ; however, in many embodiments, the functions of the microcontroller  102  as described herein may be implemented by the processing unit  118  and the microcontroller may be omitted. Accordingly, the term microcontroller  102  is meant to encompass a separate processing element from the processing unit or functionality performed by the processing unit  118  itself. 
     The track pad  114  includes a trackpad plate  104 , at least one position sensor  106 , at least one touch sensor  116 , and at least one force sensor  110 , as well as an actuator  108 . Each of the touch sensor(s)  116 , the position sensor(s)  106 , the force sensor(s)  110  and the actuator  108  are coupled to the trackpad plate  104  and the micro controller  102  and/or processing unit  118 . The computer system  100  typically further includes a display and one or more additional user interfaces (not shown). In some embodiments, the position sensor(s)  106  may be an accelerometer, motion sensor or the like. 
     One example of providing haptic feedback is now discussed, but it should be understood that this is a single example and not meant to be limiting. When using the trackpad  114  to provide input to the computer system  100 , a user may move his or her finger on the trackpad plate  104  to, and/or touch the trackpad plate at, a desired location. The touch sensor(s)  116  and the force sensor(s)  110  detect the location and force of the touch on the trackpad plate  104  respectively and send corresponding signals to the micro controller  102 . The micro controller  102  communicates with processing unit  118  inside the computer system  100 ; the processing unit  118  may generally instruct the micro controller with respect to certain operations. 
     The processing unit  118  may employ 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, the processing unit further determines if the force signal is above a threshold. If so, the processor may validate the force signal as a selection of the application of UI element. In other words, the force signal is not a false signal. The micro controller  102  then activates the actuator  108 , which moves the surface of the trackpad beneath the user&#39;s finger (as described in more detail below). The user may sense this motion, thereby experiencing haptic feedback in response to the application or UI element selection. The position sensor  106  detects how much the trackpad plate  104  moves relative to the actuator after an actuation event, or vice versa. 
     In another example, the track pad  114  may detect a user input, such as a user touch or a user force. In this example, substantially any type of user input detected may be used to provide feedback to the user. Based on the user input the track pad  114  may be activated by the processing unit  118  to move or vibrate 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 feedback is desired. In other instances, the mere reception 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 the computer system  100 . 
       FIG. 2A  illustrates a bottom view of the trackpad plate  104  coupled to bending beams and the actuator  108  in accordance with an example embodiment. As illustrated, the trackpad plate  104  is supported by four bending beams  204 A-D and coupled through gels  202 A-D. The gels  202 A-D allow relative movements or lateral motion of the trackpad plate  104  with respect the bending beams  204 A-D that are attached to a housing  206 . An attraction plate  208  is attached to the trackpad plate  104  near an edge  220  of the trackpad plate  104  and has a rectangular or a square shape in this embodiment. More specifically, in this embodiment, the attraction plate  208  is substantially parallel to the edge  220  of the trackpad plate  104 . In some embodiments, the actuator  108  may be attached to the housing  206 , and may be located outside of, and approximately adjacent to, an edge  220  of the trackpad plate  104 . In other embodiments, the actuator  108  may be attached to a bending beam plate rather than the housing. Note that edge  220  is shown in dash lines in this embodiment. The attraction plate  208  can slightly extend from the edge  220  of the trackpad plate  104 . Positioning of the attraction plate  208  and the actuator  108  may affect the overall operation of the embodiment. 
     The gap  214  between the attraction plate and the actuator may be tightly controlled, since the force exerted by the actuator on the attraction plate drops with an increase in the gap distance. In some embodiments, the gap  214  may be controlled to equal 300 μm+/−50 μm, although this distance may vary between embodiments. It may be useful to place the attraction plate and the actuator in the same X-Y plane to prevent or reduce inducing torque or pitch-type motion in the trackpad plate. Similarly, aligning the actuator and attraction plate along the x axis may help reduce or prevent torquing of the trackpad plate in-plane, as well as yaw motion. In some embodiments, the actuator may be attached to one or more bending beams in addition to, or instead of, the housing. 
     The actuator  108  includes a number of metal cores or tines or arms  210 , each metal core or tine being wound with a wire  218 . The metal cores may be magnetized when an electric current goes through the wire and electrical contacts  212 A-B. Essentially, the combination of cores and wires forms a series of electromagnets. The processing unit and/or the microcontroller  102  may activate the actuator  108  by flowing the electric current through the wire  218 , and deactivate the actuator  108  by reducing the electric current to zero. When the actuator  108  is activated by the controller  102 , the attraction plate  208  is attracted to poles  210  of the actuator  108  and moves toward the poles  210  such that the trackpad plate  104  moves toward the actuator  108  from its original position. 
     When the actuator  108  is deactivated by reducing the electric current to zero, the attraction plate  208 , along with the trackpad plate  104 , is biased away from the actuator  108  such that it returns to its original position. In the present embodiment, the gel(s) may act as a spring, returning the trackpad plate  104  to its original position when the attractive force of the haptic actuator  108  terminates. It should be appreciated that other biasing elements may be used instead of the pictured gels. For example, a spring may be used instead, as may other elastic materials. 
     In a particular embodiment, the wires for each metal core or tine  210  may be positioned on either side of the metal core. The contacts  212 A-B are all connected to a printed circuit board (PCB) (not shown) that may have connections to a specialized circuit board, such as an input device board. Electric current is provided to the wires through the two connections on the PCB. The PCB may attach to a support base. 
     Typically, movement of the track pad plate  104  is in the plane of the track pad, that is, lateral or in-plane movement. The movement of the trackpad gives the user&#39;s finger a sensation or a feedback. The sensation generated by such a back and forth movement is different from a sensation from a typical vibration as used in a cell phone. The sensation generated by the actuator  108  may be more forceful and abrupt than the sensation resulting from vibration induced by an off-center motor or other mechanical actuators. 
       FIG. 2B  illustrates a bottom view of the trackpad plate  104  with the electromagnetic actuator  108  in accordance with another embodiment. The main differences between the embodiments of  FIG. 2B  and  FIG. 2A  are the locations of the attraction plate and the actuator under the trackpad plate. As shown, the trackpad plate  104  is supported by four bending beams  204 A-D and coupled through the gels  202 A-D. The attraction plate  208  is attached to the trackpad plate  104  within the trackpad. More specifically, the attraction plate  208  is substantially parallel to the edge  220  of the trackpad plate  104  and offset from the edge. The actuator  108  may be located beneath the trackpad plate  104 , but is attached to the housing  206  and not the trackpad plate. The support base  306  for the actuator  108  may extend to the housing  206  under the trackpad plate  104 . The actuator  108  may not attach to the track pad plate  104 , or may attach to a bending beam or bending beam plate associated with the bending beam(s). Additionally, the track pad plate  104  is supported by four bending beams  204 A-D through joints or gels  202 A-D. The four bending beams are attached to housing  206 . 
       FIG. 3A  illustrates a side view of the electromagnetic actuator  108  in an embodiment. As shown, the actuator  300  includes four alternating magnetic poles or tines  322 A-D, shown as alternating north (N) and south (S) poles. It should be appreciated that alternative embodiments of the actuator may use different patterns of poles. Each of poles  322 A-D is formed from a metal core  210  and layers of electric wires  318  that are wound around the metal core  210 . In the current embodiment, the metal core  210  has a generally rectangular cross-section. The four poles  322 A-D are aligned along an X-axis and attached to a support base  306 . There is a gap  302  between each pair of poles  322 N and  322 S. All the poles  322 A-D have the same width “w” in this configuration, although in other embodiments the widths of any or all of the poles may be different. The use of a configuration of alternating pole polarity (e.g., north-south-north-south (NSNS) or south-north-south-north (SNSN)) for the actuator allows the use of an additional third central flux loop that is not present in certain other polarity configurations, such as north-south-south-north (NSSN) or south-north-north-south (SNNS). This allows larger force to be generated. Similarly, certain pole polarity configurations, such as north-north-south-south (NNSS) and south-south-north-north (SSNN), have one flux loop, which results in lower force, presumably due to a longer flux path. 
     The metal core  210  and the attraction plate  208  may be made of a relatively soft magnetic material, such as iron or steel. The soft magnetic material has a small hysteresis loop and a small coercive force as well as a small remanence such that no magnetism remains when the magnetic field is removed. In the actuator, the external magnetic filed is generated by the electric current. In a sample embodiment, the metal core  210  may be made of silicon steel. The attraction plate may be formed from iron or another suitable material. Generally, silicon steel has a higher magnetic saturation limit and a better magnetic permeability than iron or many other ferrous materials, may help improve efficiency of the system. That is, more flux may be produced with the same electric current. The material for the attraction plate may vary with the dimension of the attraction plate. For example, for a relatively thin attraction plate, silicon steel may be used. For a relatively thick plate, electrical iron  430  or even electrical iron  1010  may be used without saturation under normal operating conditions. 
       FIG. 3B  illustrates a top view of the electromagnetic actuator of  FIG. 3A . The wires  218  are wound around the metal core  210  and leave a space  310  near the top end of the pole. The bottom end of each pole is attached to the support base  306 . Electrical contacts  212 A-B for the wires  218  are also attached to the support base  306 . The attraction plate  208  has two ends  304 A and  304 B, each of which are aligned with the two ends  324 A-B of the support base  306 . In the current embodiment, the length of the attraction plate  208  is equal or longer than the two ends  324 A-B of the poles. This may facilitate a uniform magnetic field across the attraction plate  208 . 
       FIG. 4A  illustrates a side view of the electromagnetic actuator in another embodiment. In this embodiment, actuator  400  includes four alternating magnetic poles  422 A-D with different pole widths. For example, the outer poles  422 A and  422 D have a smaller pole width “W 1 ” than the width “W 2 ” of inner poles  422 B and  422 C. This variation in pole width in the actuator  400  helps form a more uniform magnetic field across the attraction plate than the actuator  300 .  FIG. 4B  illustrates a top view of the electromagnetic actuator of  FIG. 4A .  FIG. 4C  is a perspective view of the actuator  400 . Note that the figures are not to scale. The magnetic poles may include metal cores  410 . The inner poles or tines are wider than the outer poles or tines, which prevents saturation of the inner tines due to the presence of the third flux loop in a NSNS or SNSN pole configuration. Additional benefits include preventing in-plane twisting of the trackpad plate from occurring, since higher force is generated over these central poles or tines. 
     The metal core  210  may have a rectangular shape as shown in  FIGS. 3A and 4A . In alternative embodiments, any or all metal cores  210  may be square in cross-section instead. The metal core also may be a cross-section of a square with rounded edges. The core&#39;s cross-section also may be circular. It will be appreciated by those skilled in the art that the metal core may vary in shape and dimension. Each shape has an aspect ratio of cross-sectional area per unit circumference. Higher aspect ratios result in lower electrical coil resistances for the same surface area. 
       FIG. 5A  illustrates a side view of the electromagnetic actuator in an alternative embodiment.  FIG. 5B  illustrates a top view of the electromagnetic actuator of  FIG. 5A . In this embodiment, actuator  500  includes four alternating magnetic poles  522  with two different pole widths “W 1 ” and “W 2 ”, similar to actuator  400 . However, each metal core  510  terminates in a plate  502 . The plate  502  extends from the metal core  510  to each side, thereby constraining the wires between the plate  502  and the support  306 . This plate  502  helps increase magnetic force by about 10%. As the plate  502  extends sideway, the magnetic field near the ends  304 A-B of the attraction plate  208  may be stronger for the actuator  500  than that for the actuator  400 . The reduced edge effects may help increase the magnetic force. As an example, W 1  is 6.35 mm, W 2  is 12.85 mm, a gap between two tines is 2.5 mm to allow space for the wire. A gap between the outer tine and edge is 1.75 mm to allow space for the wires. The tine or arm has a height of 6.65 mm. 
       FIG. 6A  illustrates a side view of the electromagnetic actuator in a further embodiment.  FIG. 6B  illustrates a top view of the electromagnetic actuator of  FIG. 6A . In this particular embodiment, actuator  600  includes four alternating magnetic poles  622  with two different pole widths “W 1 ” and “W 2 ”. However, unlike actuator  400 , actuator  600  may have a triangular portion or crown  604 A on top of the otherwise rectangular metal core body  604 B, such that the metal core  610  has a cross-section equal to the addition of the triangular portion  604 A and the rectangular body  604 B. The triangular portion  604 A of the metal core  610  changes relationship between a magnetic force and the distance between the attraction plate and the poles. For example, without the triangular portion  604 A, the magnetic force may increase non-linearly with decreasing distance between attraction plate and the poles. With the triangular portion added to the metal core, the force may increase less non-linearly with decreasing distance between the attraction plate and the poles. It will be appreciated by those skilled in the art that the triangular portion  604 A may vary in shape. 
     The attraction plate  608  has a series of recesses contoured by edge  602 . Each recess may be matched to the shape of the triangular portion  604 A of the actuator  600  such that equal spacing is formed between the attraction plate  608  and the actuator  600 . 
     Although the examples in  FIGS. 2-6  show the use of four poles, the number of poles may vary with the dimension of the poles and the dimension of the trackpad. For example, the number of poles may increase with the dimension of the trackpad and may decrease with the width of the pole. 
     For both actuators  300  and  400 , assuming that the gap  302  remains the same and the total distance between the two ends  324 A and  324 B of the actuator are the same except the pole width variation, the integrated magnetic force is about the same. However, the magnetic field distribution across the X-axis is more uniform for actuator  400  with different pole widths than that for actuator  300  with constant pole width. 
       FIG. 7  illustrates simulated magnetic field  700  for the actuator of  FIGS. 3A and 3B  in accordance with that embodiment. For actuator  300 , the magnetic field is not uniform across the X-axis. Specifically, the magnetic field lines  702  are closer in the middle section  704 B than the outer section  704 A and  704 C. In this simulation, the total force along the Y-axis is 20.12 N and along the X-axis is 0.02 N, given that the gap between the attraction plate and the actuator is 350 μm. The electric current is 3 amperes. There are three layers of wire; each layer has 30 turns such that there is a total of 90 turns for all the three layers. The wire has a 34 American Wire Gage (AWG) diameter. 
     In contrast,  FIG. 8  illustrates a sample and simulated magnetic field for the actuator of  FIGS. 4A and 4B . For actuators  400 ,  500 ,  600 , the magnetic fields are more uniform. Particularly, magnetic field lines  802  are uniformly spaced for regions  804 A-C. 
     It will be appreciated by those skilled in the art that the number of turns of the wires may vary, and the number of layers of the wires, the wire diameter, and the height of the metal core may vary. 
     As illustrated in some embodiments, the actuator is flat and small in height, which is suitable for use in small and thin portable computer devices, such as notebook computers, tablet devices, music and media devices and smart phones. The actuator also has a relatively high magnetic force to attract a attraction plate to move forward and back quickly. The actuator may also have a uniform magnetic field from one end to the other end across the attraction plate. 
     The actuator can be constructed as a single unit from a laminated sheet metal. The metal cores are formed by stamping to remove some material to form spaces between each core from the laminated sheet metal. The laminated sheet metal is stamped to form an integral support  306  for a series of metal cores. The series of metal cores is not attached to the support  306 . Such a layered unit construction method for the actuator may increase dimensional precision of each pole and reduces the need for integration of different components which are fabricated separately. The number of poles may be optimized for efficiency versus working distance. In a particular embodiment, the number of poles is four. Such a fabrication process is relatively low cost, as the actuator is made from a flat laminated metal. Commercially, high performance steel sheets are available. The metal sheets may be cut into the desired pattern. 
       FIG. 9  is a flow chart illustrating sample steps for fabricating the actuator in accordance with an embodiment. Method  900  starts with providing a laminated metal sheet at operation  902 , and is followed by stamping the metal sheet into a desired pattern of an array of metal cores at operation  906 . Method  900  continues with annealing at operation  910 . Annealing may help improve the permeability characteristics of the metal cores. It may better align magnetic domains after mechanical processing such as stamping may have misaligned the magnetic domains, especially around the edges and corners of the metal cores. 
     Method  900  may also include winding electrical wires around a bobbin and sliding the wound wires on the metal cores at operation  914 . Method  900  further includes soldering two ends of each wire to a printed circuit board (PCB) on a support base at operation  918 . 
       FIG. 10  illustrates a comparison of displacement versus gap for annealed and non-annealed actuators in an embodiment. As shown, data for annealed actuators show larger displacements than data for non-annealed actuators for large gaps. For example for air gap of 350 μm, annealed actuators have displacement of about 150 μm while non-annealed actuators have displacements of 110 μm. For smaller gaps, annealing does not affect the displacement to any great degree. 
     This layered unit construction also may reduce eddy currents that may otherwise be generated in the actuator. Potential benefits of reducing the eddy current include reducing heat generation and increasing power efficiency for the actuator. 
     To wind the wire on the metal core, the wire may be first wound on a bobbin. Then, the wound wire slides on the metal core. The wire is heated as the wire is wound on the bobbin, so that various turns are glued to each other to provide better packing. 
     Having described several embodiments, it will be recognized by those skilled in the art that various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the invention. Additionally, a number of well-known processes and elements have not been described in order to avoid unnecessarily obscuring the present invention. Accordingly, the above description should not be taken as limiting the scope of the invention. 
     Those skilled in the art will appreciate that the presently disclosed embodiments teach by way of example and not by limitation. Therefore, the matter contained in the above description or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. The following claims are intended to cover all generic and specific features described herein, as well as all statements of the scope of the present method and system, which, as a matter of language, might be said to fall therebetween.

Metadata:
Filing Date: 20171030
Publication Date: 20200505
Grant Date: 20200505
Priority Date: 20120612
Inventors: KESSLER, PATRICK
PATEL, DHAVAL CHANDRAKANT
HARLEY, JONAH A.
DEGNER, BRETT W.
RUNDLE, NICHOLAS ALAN
AUGENBERGS, PETERIS K.
LUBINSKI, NICHOLAUS
Staton, Kenneth L
LEUNG, OMAR SZE
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F3/03547", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F7/1638", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F41/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F41/064", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/016", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/03547", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49071", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/016", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T29/49071", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01F7/1653", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F41/064", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F7/1653", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F7/1638", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F7/1653", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F41/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/03547", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01F7/1638", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0414", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/016", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01F41/064", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49071", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 48703861