Patent Publication Number: US-2012038469-A1

Title: Actuator assembly and electronic device including same

Description:
FIELD OF TECHNOLOGY 
     The present disclosure relates to an actuator assembly for providing tactile feedback in an electronic device that includes a touch-sensitive input device. 
     BACKGROUND 
     Electronic devices, including portable electronic devices, have gained widespread use and may provide a variety of functions including, for example, telephonic, electronic text messaging and other personal information manager (PIM) application functions. Portable electronic devices can include several types of devices including mobile stations such as simple cellular phones, smart phones, Personal Digital Assistants (PDAs), and laptop computers. 
     Devices such as PDAs or smart phones are generally intended for handheld use and ease of portability. Smaller devices are generally desirable for portability. Touch-sensitive devices constructed of a display, such as a liquid crystal display (LCD), with a touch-sensitive overlay are useful on such handheld devices as such handheld devices are small and are therefore limited in space available for user input and output devices. Further, the screen content on the touch-sensitive devices can be modified depending on the functions and operations being performed. 
     Tactile feedback for such touch-sensitive input devices provides a positive confirmation of, for example, touch selection. The provision and control of tactile feedback in touch-sensitive devices is desirable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present disclosure will now be described, by way of example only, with reference to the attached Figures, wherein: 
         FIG. 1  is a simplified block diagram of components including internal components of a portable electronic device according to an example embodiment; 
         FIG. 2  is a perspective view of an example of a portable electronic device; 
         FIG. 3  is an exploded view of portions of the portable electronic device of  FIG. 2 , including an actuator assembly in accordance with an example embodiment; 
         FIG. 4  is an exploded view of the actuator assembly of  FIG. 3 ; 
         FIG. 5  is a further exploded view of the actuator assembly of  FIG. 3 ; 
         FIG. 6  is a perspective view of the actuator assembly of  FIG. 3 ; and 
         FIG. 7  is another perspective view of the actuator assembly of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     The following describes an actuator assembly for use in an electronic device. The actuator assembly includes a support tray, an actuator supported on the support tray, a force sensor spaced laterally from the actuator, and a cover covering the actuator and coupled to the support tray. A portion of the cover is movable relative to the support tray when the actuator is actuated. 
     It will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the example embodiments described herein. However, it will be understood by those of ordinary skill in the art that the example embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the example embodiments described herein. Also, the description is not to be considered as limited to the scope of the example embodiments described herein. 
     The actuator assembly provides a relatively thin device to provide desirable tactile feedback, for example, to simulate actuation of a dome switch upon touching or upon application of an external force to the touch-sensitive display, confirming receipt of input to the user. The tactile feedback provides a positive response and reduces the chance of input errors such as double entry, decreasing use time and increasing user-satisfaction. The actuator assembly includes a metal actuator sheet that facilitates grounding of the touch-sensitive display that is disposed on the actuator sheet. The actuator sheet facilitates pre-loading of the actuator assembly during production of the actuator assembly. The tolerance of the actuator assembly may be controlled to a tight tolerance at a lower cost by comparison to ensuring very tight tolerances for all individual parts. The force sensors are laterally spaced from the actuators in the support tray such that a preload on the force sensors, which is the load on the force sensors absent an external applied force by a user pressing on the touch-sensitive display, may differ from a preload on the actuators. Thus, the preload on the force sensors and the actuators may be separately controlled. 
     Example embodiments of the actuator assembly described herein are utilized in an electronic device such as a portable electronic device that includes a touch-sensitive display.  FIG. 1  shows a simplified block diagram of components including internal components of a portable electronic device according to an example embodiment. 
     The portable electronic device  100  includes multiple components such as a processor  102  that controls the operations of the portable electronic device  100 . Communication functions, including data and voice communications, are performed through a communication subsystem  104 . Data received by the portable electronic device  100  is decompressed and decrypted by a decoder  106 . The communication subsystem  104  receives messages from and sends messages to a wireless network  150 . The wireless network  150  may be any type of wireless network, including, but not limited to, data-centric wireless networks, voice-centric wireless networks, and dual-mode networks that support both voice and data communications over the same physical base stations. The portable electronic device  100  is a battery-powered device and includes a battery interface  142  for receiving one or more rechargeable batteries  144 . 
     The processor  102  also interacts with additional subsystems such as a Random Access Memory (RAM)  108 , a flash memory  110 , a display  112  with a touch-sensitive overlay  114  connected to an electronic controller  116  that together comprise a touch-sensitive display  118 , actuators  120 , force sensors  122 , an auxiliary input/output (I/O) subsystem  124 , a data port  126 , a speaker  128 , a microphone  130 , short-range communications  132  and other device subsystems  134 . User-interaction with the graphical user interface is performed through the touch-sensitive overlay  114 . The processor  102  interacts with the touch-sensitive overlay  114  via the electronic controller  116 . Information, such as text, characters, symbols, images, icons, and other items that may be displayed or rendered on a portable electronic device, is displayed on the touch-sensitive display  118  via the processor  102 . The processor  102  may also interact with an accelerometer  136  as shown in  FIG. 1 . The accelerometer  136  may include a cantilever beam with a proof mass and suitable deflection sensing circuitry. The accelerometer  136  may be utilized for detecting direction of gravitational forces or gravity-induced reaction forces. 
     To identify a subscriber for network access according to the present embodiment, the portable electronic device  100  uses a Subscriber Identity Module or a Removable User Identity Module (SIM/RUIM) card  138  inserted into a SIM/RUIM interface  140  for communication with a network such as the wireless network  150 . Alternatively, user identification information may be programmed into the flash memory  110 . 
     The portable electronic device  100  also includes an operating system  146  and software components  148  that are executed by the processor  102  and are typically stored in a persistent store such as the flash memory  110 . Additional applications may be loaded onto the portable electronic device  100  through the wireless network  150 , the auxiliary I/O subsystem  124 , the data port  126 , the short-range communications subsystem  132 , or any other suitable device subsystem  134 . 
     In use, a received signal such as a text message, an e-mail message, or web page download is processed by the communication subsystem  104  and input to the processor  102 . The processor  102  then processes the received signal for output to the display  112  or alternatively to the auxiliary I/O subsystem  124 . A subscriber may also compose data items, such as e-mail messages, for example, which may be transmitted over the wireless network  150  through the communication subsystem  104 . For voice communications, the overall operation of the portable electronic device  100  is similar. The speaker  128  outputs audible information converted from electrical signals, and the microphone  130  converts audible information into electrical signals for processing. 
       FIG. 2  is a perspective view of an example of a portable electronic device  100 . The portable electronic device  100  includes a housing  202  that is suitable for housing the internal components shown in  FIG. 1 . The housing includes a frame  204  that frames the touch-sensitive display  118  for user-interaction with the touch-sensitive display  118 . Although not shown in the figures, the portable electronic device  100  of  FIG. 2  may also include a physical keyboard (not shown) such that the processor  102  (shown in  FIG. 1 ) interacts with the keyboard and the housing  202  is constructed to accommodate the keys of the keyboard. 
       FIG. 3  is an exploded view of portions of the portable electronic device  100  including an actuator assembly  300 . The housing  202 , shown in  FIG. 2 , of the portable electronic device  100  includes a front  302 , that includes the frame  204 , and the back  304 . The back  304  of the housing  202  includes an opening that may be covered by a plate that is releasably attachable to the back  304  for insertion and removal of, for example, the SIM/RUIM card  138  shown in  FIG. 1 . In the example of  FIG. 3 , the battery  144  is shown along with a printed circuit board  306 . The touch-sensitive display  118  is disposed on the actuator assembly  300  and is available for user interaction through an opening, defined the by frame  204 , in the front  302  of the housing  204 . 
     Referring now to  FIG. 4  through  FIG. 7 , various views of the actuator assembly  300  are shown. The actuator assembly  300  includes, for example, four actuators  120 , which in the present embodiment are piezoelectric disk actuators. Different numbers of actuators  120  may be utilized in other embodiments. The actuators  120  are supported by a support tray  402  that is generally rectangular in shape. The support tray  402  includes a base  403  with a lip  404  that protrudes from one side of the base  403  and extends generally around the base  403 . The lip  404  extends only partly around the base  403  as a break in the lip  404  is provided for connection of a flexible printed circuit board to two force sensors  122  near one end of the support tray  402 , as described below. A cut-out portion in the support tray  402  is utilized for connection of the flexible printed circuit board to two additional force sensors  122  near an opposing end of the support tray  402 . 
     Four apertures, that are generally circular, extend through the support tray  402 . Each aperture is located near a respective corner of the base  403 . The apertures correspond with the locations of the actuators  120 , referred to below. The apertures include an additional cut-away tab for connection to the flexible printed circuit board. A margin of the base  403  around each of the four apertures provides a seat for the respective actuator  120 . 
     In addition to the apertures, stops  406  are formed in the support tray  402 . The stops  406  project from the base  403 , protruding in the same direction that the lip protrudes. In the present example, the stops  406  are generally cylindrical and are adjacent the four apertures that provide seats for the actuators. Eight stops  406  are utilized to limit bending forces on the actuators  120 , caused by an external applied force on the touch-sensitive display  118 . 
     The support tray  402  may be formed of metal such as stainless steel. Additional holes in the support tray  402  are provided for alignment with holes in other components of the actuator assembly  300 . 
     A non-conductive tape (not shown) is disposed on the support tray  402  and adhered to the support tray  402  and the actuators  120  to electrically isolate the actuators  120  from the support tray  402 . The non-conductive tape may cover the entire support tray  402 . 
     Each actuator  120  includes a piezoelectric disk such as a PZT ceramic disk  414  adhered to a metal substrate  416  of larger diameter than the piezoelectric disk  414  for bending when the piezoelectric disk  414  contracts diametrically as a result of build up of charge at the piezoelectric disk  414 . The metal substrate  416  of the actuator  120  is supported on the margin of the base  403  around each of the four apertures. The non-conductive tape electrically isolates the metal substrate  416  and the piezoelectric disk  414  from the support tray  402 . 
     Conductive tape may be utilized to adhere each piezoelectric disk  414  of each actuator  120  to a flexible printed circuit board  422 . The flexible printed circuit board  422  includes conductive traces that are electrically connected to the piezoelectric disks  414  to connect the actuators  120  to, for example, the printed circuit board  306  of the portable electronic device  100 . The flexible printed circuit board  422  also includes legs  424  that extend to an opposing side of the support tray  402  through the break in the lip  404  near one end of the support tray  402  and through the cut-out portion near the opposing end of the support tray  402 . Each of four force sensors  122  is connected to a respective leg  424  of the flexible printed circuit board  422 . In the present example, the force sensors  122  comprise force-sensing resistors and are attached to a backside of the lip  404  of the support tray  402  by resilient plungers  426  that are disposed between the force sensors  122  and the support tray  402 . The force sensors  122  are attached, via the plungers  426  to a backside of the lip  404  of the support tray  402  by a non-conductive adhesive such that the actuators  120  are disposed on one side of the support tray  402  and the force sensors  122  are laterally spaced from the force sensors  122  and are disposed on an opposite side of the support tray  402 . The plungers  426  are resilient plungers of, for example, silicone. Four additional plungers  428  are disposed on the actuators  122 , with a respective plunger  428  on each actuator  122 . The additional plungers  428  are also resilient and may be, for example, silicone. The force sensors  122  may be preloaded, between the actuator assembly and a base or other support within the housing  202  that provides a base for the actuator assembly  300 , to thereby control the preload on the force sensors  122  separate of the preload on the actuators  120 . 
     Still referring to  FIG. 4  through  FIG. 7 , an actuator sheet  430  covers a portion of the flexible printed circuit board  422  and the actuators  120  and is coupled to the support tray  402 . The actuator sheet  430  includes a generally rectangular inner sheet  432  with two side rails  434  on opposite sides of the inner sheet  432 . The inner sheet  432  is spaced from each side rail  434  by a respective intermediate gap. Each intermediate gap is interrupted by resiliently flexible arms  436  that join the inner sheet  432  to the side rails  434 . The arms  434  form a jog, such that the location at which each of the arms  434  joins the inner sheet  432  is offset from alignment with the location that the arm  434  joins one of the side rails  434 , to facilitate movement of the inner sheet  432  relative to the side rails  434 . The inner sheet  432 , side rails  434  and resiliently flexible arms  436  may be integral portions of a sheet. 
     The inner sheet  432  includes alignment holes for aligning the actuator sheet  430  with the support tray  402 . In the present example, the actuator sheet  430  is a metal sheet of, for example, spring steel to facilitate grounding of the touch-sensitive display  118  that is disposed on the actuator sheet  430 . The side rails  434  are coupled to the support tray  402  by, for example, spot welding the side rails  434  to the lip  404  of the support tray  402 . Alternatively, the actuator sheet  430  may form a mechanical interlock with the support tray  402 . The inner sheet  432  is movable relative to the side rails  434  and the support tray  402  for moving the touch-sensitive display when the actuators  120  are actuated. The actuator sheet  430  facilitates pre-loading of the actuators  120  during production of the actuator assembly  300  such that a bending force acts on the actuators  120 , and the actuators  120  provide a spring force in return, when the actuators  120  are not charged and the actuator assembly  300  is in a rest position. 
     The touch-sensitive display  118  is an assembly of components including the LCD display  112 , the overlay  114  and controller  116  (shown in  FIG. 1 ). The touch-sensitive display  118  may be a capacitive touch-sensitive display, for example, and a user&#39;s touch on the touch-sensitive display may be determined by determining the X and Y location of the touch with the X location determined by a signal generated as a result of capacitive coupling with a touch sensor layer and the Y location determined by the signal generated as a result of capacitive coupling with another touch sensor layer. Each of the touch-sensor layers provides a signal to the controller  36  that represents the respective X and Y touch location values. Thus a feature such as a virtual button or other feature displayed on the touch-sensitive display  118  may be selected by a mapping of the touch location to a feature on the touch-sensitive display  118 . 
     The touch-sensitive display  118  is coupled to the inner sheet  432 . The actuator assembly  300  acts on the touch-sensitive display  118  such that when the actuators  120  are actuated, a force is transmitted from the actuators  120 , through the actuator sheet  430  and to the touch-sensitive display  118 , to move the touch-sensitive display  118  relative to the back  304  of the housing  202  of the portable electronic device  100 . 
     A charge applied to the piezoelectric disks  414  of the actuators  120  results in the piezoelectric disk  414  shrinking diametrically, causing the metal substrate  416  and therefore the entire actuator  120 , to bend and apply a force to the inner sheet  432  of the actuator sheet  430 . Because the inner sheet  432  is moveable relative to the support tray  402 , the inner sheet  432  may be moved away from the support tray  402  as the resiliently flexible arms  436  are flexed. The touch-sensitive display  118  may be moved away from the support tray  402 , and thus, away from the back  304  of the housing  202  of the portable electronic device  100 . The removal of the charge, causes the actuators  120  to return to the rest position and the resiliently flexible arms  436  facilitate movement of the inner sheet  432  to return to the rest position. Thus, the touch-sensitive display  18  is moved back to the rest position. The actuators  120  are connected through the flexible printed circuit board  416  to, for example, the printed circuit board of the portable electronic device  100  and may be controlled by drive circuitry connected to the processor  102  or other microprocessor. 
     The force sensors  122  are utilized to determine a value related to an applied force by a user touch on the touch-sensitive display  118  as a force applied to the touch-sensitive display  118  is translated to the force sensors  122 . The actuators  120  may be controlled to provide movement of the touch-sensitive display  118  in response to detection of an applied force, on the touch-sensitive display  118 , that meets or exceeds a force threshold. 
     The mechanical work performed by the actuators  120  may be controlled to control the force and movement of the touch-sensitive display  118 . Fluctuations in mechanical work performed as a result of, for example, temperature, may be reduced by modulating the current to the actuators  120  to control the charge. An increase in the charge increases the force on the touch-sensitive display  118  away from the support tray  402  and a decrease in the charge decreases the force on the touch-sensitive display  118 , facilitating movement of the touch-sensitive display  118  toward the base  82 . In the present example embodiment, each of the actuators  120  is controlled equally and concurrently. It will be appreciated that the piezoelectric actuators may be controlled separately, however. The portable electronic device  100  is controlled generally by modulating a force on the touch-sensitive display  118  in response to detection of an applied force on the touch-sensitive display  118 . 
     The embodiments shown and described herein illustrate examples only and many modifications may be made. For example, the number of actuators may differ. In one example, four actuators are located near respective corners of the actuator assembly. 
     An actuator assembly, for use in an electronic device, includes a support tray, an actuator supported on the support tray, a force sensor spaced laterally from the actuator, and a cover covering the actuator and coupled to the support tray. A portion of the cover is movable relative to the support tray when the actuator is actuated. 
     An electronic device includes a housing, a touch-sensitive input device exposed by the housing, and an actuator assembly. The actuator assembly is housed in the housing and coupled to the touch-sensitive input device. 
     The actuator assembly provides a relatively thin device to provide desirable tactile feedback, for example, to simulate actuation of a dome switch upon touching the touch-sensitive display, confirming receipt of input to the user. The tactile feedback provides a positive response and reduces the chance of input errors such as double entry, decreasing use time and increasing user-satisfaction. Further, the actuator assembly includes a metal actuator sheet that facilitates grounding of the touch-sensitive display that is disposed on the actuator sheet. The actuator sheet facilitates pre-loading of the actuator assembly during production of the actuator assembly. Furthermore, the tolerance of the actuator assembly may be controlled to provide an assembly with tight tolerance. The tolerance of the entire assembly may be controlled at a lower cost by comparison to controlling the tolerance for all the parts individually. The force sensors are laterally spaced from the actuators in the support tray such that a preload on the force sensors, which is the load on the force sensors absent an external applied force by a user pressing on the touch-sensitive display, may differ from a preload on the actuators. Thus, the preload on the force sensors and the actuators may be separately controlled. 
     While the embodiments described herein are directed to particular implementations of the actuating assembly and the portable electronic device and the, it will be understood that modifications and variations may occur to those skilled in the art. All such modifications and variations are believed to be within the sphere and scope of the present disclosure.