Patent Publication Number: US-2010117809-A1

Title: Display module with piezoelectric haptics

Description:
FIELD OF THE INVENTION 
     The field of the invention relates to displays and more particularly, to touch panel displays. 
     BACKGROUND OF THE INVENTION 
     Touch panel displays are known. Touch panel displays are often used where space is limited, such as in cell phones. 
     Touch panel displays may include a number of touch pads. The touch pads typically have discrete key locations identified by respective alpha-numeric symbols that are displayed on touch screens such as analog, resistive, infrared, acoustic, capacitive or electromagnetic inductively operated screens. 
     One difficulty with touch pads is that they do not always provide the user with satisfactory feedback when a touch pad is activated. For example, activation of a key on a conventional keyboard produces detectable motion as the key is activated. On regular phone keypads, a popple dome may be placed underneath each key. Each dome deflects downward to provide a perceptible tactile “click” when a key is activated. 
     In the case of a touch pad, the completion of a keystroke can often be seen on the user&#39;s screen, but cannot be felt. In the case of capacitive or resistive touch pads, the user simply places his/her finger on the touch pad. In either case, a controller detects a change in capacitance or resistance as an indication of activation of the touch pad. 
     While touch panels work relatively well, they are often subject to errors. For example, if the processor monitoring the touch pads is busy with other matters (e.g., placing a call in the case of a cell phone) and doesn&#39;t immediately display the character associated with an activated touch pad, then the user may immediately activate the touch pad a second time leading to unexpected results. Similarly, if a user is unsure that he/she has activated a touch pad, then the user may activate the touch pad a second time, again leading to unexpected results. Because of the importance of touch panels, a need exists for better method of confirming activation of touch pads on touch panels. 
     SUMMARY  
     A mobile communication terminal is provided. The mobile communication terminal includes a touch sensitive liquid crystal display (LCD) module having a predetermined plurality of touch sensitive areas and a plurality of piezoelectric elements disposed along a periphery of a cover glass of the display module wherein activation of the piezoelectric elements provides tactile feedback to a user of activation of a portion of the touch sensitive LCD module by the user. 
     In another embodiment the mobile communication terminal includes the context wherein the touch sensitive LCD module further comprises an LCD cover glasses that house the liquid crystal. 
     In another embodiment the mobile communication terminal includes the context wherein the LCD further comprises a front display cover glass surface and a rear display cover glass surface with the plurality of piezoelectric elements disposed on the rear surface along a set of outside edges of the LCD active area. 
     In another embodiment the mobile communication terminal includes a plurality of thin film wires disposed on the rear surface connecting the plurality of piezoelectric elements to a driver. 
     In another embodiment the mobile communication terminal includes a plurality of flex circuit boards connecting the plurality of piezoelectric elements to a driver. 
     In another embodiment the mobile communication terminal includes a controller that detects activation of a portion of the touch sensitive display and in response activates at least some of the plurality of piezoelectric elements. 
     In another embodiment the mobile communication terminal includes a drive signal applied to the at least some of the piezoelectric elements. 
     In another embodiment the mobile communication terminal includes the context wherein the drive signal further comprises a temporal length of 0.001 to 0.5 seconds first following activation of the portion of the touch sensitive display. 
     In another embodiment, the mobile communication terminal includes an LCD, a touch sensitive panel having a plurality of discrete, non-overlapping touch sensitive areas, said touch sensitive panel disposed over a viewing surface of the LCD and a plurality of piezoelectric elements disposed along a periphery of a rear surface of the LCD glass. 
     In another embodiment, the mobile communication terminal is a cellular telephone. 
     In another embodiment, the mobile communication terminal includes the context wherein the cellular telephone further comprises a housing and flexible mount wherein the flexible mount isolates the housing from vibration from the LCD display. 
     In another embodiment, the mobile communication terminal includes an LCD having an upper viewing cover glass and a lower cover glass, a touch sensitive member disposed on the upper viewing glass cover of the LCD and a plurality of piezoelectric elements disposed around a periphery of the lower cover glass and outside of a viewing area of the LCD. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a mobile communication terminal in accordance with an illustrated embodiment of the invention; 
         FIG. 2  is a cut-away side view of an LCD display module that may be used with the mobile communication terminal of  FIG. 1 ; 
         FIG. 3  is a bottom view of an LCD display that may be used within the LCD display module of  FIG. 2 ; 
         FIG. 4  shows a lower LCD glass of the LCD display of  FIG. 3  with a set of thin film wires on a rear surface; 
         FIG. 5  shows the lower LCD glass of  FIG. 4  with a dielectric layer disposed over the thin film wires; 
         FIG. 6  shows the lower LCD glass of  FIG. 5  with piezoelectric elements disposed over the dielectric layer and with a flex connector connected to the thin film wires; and 
         FIG. 7  shows a cut-away side view of the LCD display module of  FIG. 1  after the steps of  FIGS. 4-7 . 
     
    
    
     DETAILED DESCRIPTION OF AN ILLUSTRATED EMBODIMENT 
       FIG. 1  is a block diagram of a mobile communication terminal (e.g., a cellular telephone)  10  with a touch sensitive liquid crystal display (LCD) module  12  shown generally in accordance with an illustrated embodiment of the invention. In the case where the device  10  is a cellular telephone, the device  10  may include a controller  15  and a transceiver  16 . 
     The touch sensitive LCD module  12  may include LCD glasses  14  with a predetermined set of discrete, non-overlapping touch sensitive areas  20 ,  22 . The touch sensitive areas  20 ,  22  may use any appropriate touch detection mechanism (e.g., capacitance, resistance, optical, acoustic, etc.) incorporated into a transparent member (e.g., a panel, flexible member, etc.)  24  disposed over a viewing surface of the LCD glasses  14 . 
     In order to place a call, a user (not shown) may activate the mobile communication terminal  10  and enter a dialed number through one or more of the touch sensitive areas  20 ,  22  located on the LCD galsses  14  of the touch panel module  12 . A touch panel processor  18  within the controller  15  may monitor the touch sensitive areas  20 ,  22  to detect the string of numbers. The touch panel processor  18  may identify the specific touch pads  20 ,  22  by monitoring each row and column of the touch panel  24 . 
     Once the touch panel processor  18  has identified the activated touch sensitive area  20 ,  22 , the touch panel processor  18  may identify the digit or action intended and proceed accordingly. For example, if the activated touch sensitive area  20 ,  22  is a digit, then the touch panel processor  18  may accumulate the digit in anticipation of placing a call. If the touch sensitive area  20 ,  22  is MAKE CALL button  20 ,  22 , then the touch panel processor  18  may transfer a collected sequence of digits to the transceiver  16 . 
     In response, the transceiver  16  may search for a local base station and request a radio frequency channel. Once a channel has been granted, the transceiver  16  may transfer the sequence of digits to the base station, the base station may set up a call connection with the called party and the call may proceed in a conventional manner. 
     Under illustrated embodiments of the invention, the touch sensitive LCD module  12  provides tactile feedback in response to activation of each touch sensitive area  20 ,  22 . Tactile feedback in this case means a tactile sensation delivered to the finger activating a touch sensitive area  20 ,  22  without delivering that same tactile sensation to the outside surface  11  of the mobile communication terminal  10 . 
       FIG. 2  is a cut-away side view of the LCD galsses  14  within the touch sensitive LCD module  12 . As shown in  FIG. 2 , the LCD glasses  14  contain a pair of cover glass plates  100 ,  104  including an upper cover glass  100  on a viewing side, a lower cover glass  104  on the bottom and the liquid crystal  102  located between the glass plates  102 ,  104 . Also shown in  FIG. 2  is a set of piezoelectric elements  106 ,  108  attached to a bottom surface of the lower glass plate  104  and extending along a periphery of the lower glass plate  104 . 
       FIG. 3  is a bottom view of the lower glass plate  104 . As shown in  FIG. 3 , the lower glass plate  104  includes four piezoelectric elements  106 ,  108 ,  110 , 112  extending along the periphery of the plate  104  and only along the periphery. The piezoelectric elements  106 ,  108 ,  110  and  112  are placed outside the active area of the LCD. 
     The signal to the four piezoelectric elements is applied to top and bottom surfaces (i.e., the top surface is adjacent the glass and the bottom faces away from the glass). The piezoelectric elements may have wrapped-around electrodes that extends an electrode on one surface to the other surface through side electrode connection. With wrapped-around electrode a piezoelectric element could thus be accessed electrically from one surface. When the piezoelectric elements are activated on the top and bottom surfaces, the piezoelectric elements bend the predominant surfaces of the LCD display  14 . This rapid bending causes acceleration (i.e., vibration) that is perpendicular to the predominant surfaces of the LCD glasses  14 . 
     In use, the piezoelectric elements  106 ,  108 ,  110 ,  112  may be activated in conjunction with detection of activation of any of the touch sensitive areas  20 ,  22 . Included within the controller  15  may be one or more drivers  26 ,  28 ,  30 ,  32  for imposing an electric signal onto the piezoelectric elements  106 ,  108 ,  110 ,  112 . Under one embodiment one driver  26 ,  28 ,  30 ,  32  is provided for each respective piezoelectric element  106 ,  108 ,  110 ,  112 . Under another embodiment, one driver  26 ,  28 ,  30 ,  32  may be provided that drives all of the piezoelectric elements  106 ,  108 ,  110 ,  112  in parallel. 
     Also included within the controller  15  may be a signal source  34  that provides a drive signal to the piezoelectric elements  106 ,  108 ,  110 ,  112  through the drivers  26 ,  28 ,  30 ,  32 . Under one illustrated embodiment, the drive signal provided by the signal source  34  may be a single wave or a pulse train. 
     In use, the touch panel processor  18  monitors the touch sensitive areas  20 ,  22  for activation. Upon activation of a touch sensitive area  20 ,  22 , the touch panel processor  18  activates the piezoelectric elements  106 ,  108 ,  110 ,  112  for a predetermined time period (e.g., 0.001-0.5 seconds). Under one illustrated embodiment, the touch panel processor  18  sets a timer  36  with the predetermined time period and at the same time activates the drivers  26 ,  28 ,  30 ,  32  thereby applying the drive signal to the piezoelectric elements  106 ,  108 ,  110 ,  112 . At the end of the predetermined time period, the touch panel processor  18  deactivates the piezoelectric elements  106 ,  108 ,  110 ,  112 . 
     By activating the piezoelectric elements  106 ,  108 ,  110 ,  112  for the predetermined time period first following detection of activation of a touch sensitive area  20 ,  22 , the user is given tactile feedback. The tactile feedback is this case is somewhat similar to the distinctive “click” felt when a user activates a key with popple dome in a regular keypad. 
     Moreover, since the piezoelectric elements  106 ,  108 ,  110 ,  112  are attached to the bottom glass  104  around the periphery, the location of the piezoelectric elements does not interfere with operation of the LCD 
       FIGS. 4-7  show details of the construction of the LCD glasses  14 . As shown in  FIG. 4 , a set of transparent thin film wires may be formed on a bottom surface of the lower glass  104 . For example the film material could be indium tin oxide (ITO)As shown, a first set of contacts  200  are provided for contact with a first piezoelectric element  106 , a second set of contacts  202  are provided for contact with a first piezoelectric element  110 , a third set of contacts  204  are provided for contact with a first piezoelectric element  108  and a fourth set of contacts  206  are provided for contact with a first piezoelectric element  112 . 
     Once the thin film wires are disposed on the lower glass  104 , a decorative dielectric layer may be disposed on the lower surface as shown in  FIG. 5 . In this case, the contacts  200 ,  202 ,  204  and  206  are left exposed. 
     In a subsequent step (shown in  FIG. 6 ) the piezoelectric elements  106 ,  108 ,  110 ,  112  are bonded to the dielectric layer using an appropriate adhesive (e.g., an anisotropic paste). As part of the bonding process, the contacts  200 ,  202 ,  204 ,  206  are bonded to the same surface of the piezoelectric elements  106 ,  108 ,  110 ,  112  that have wrapped-around electrode. A flex connector  208  is also folded across the end of the lower glass  104  to form a connection between the connectors  200 ,  202 ,  204 ,  206  and controller  15 . 
     In another illustrated embodiment, the controller  15  may only activate a portion of the piezoelectric elements  106 ,  108 ,  110 ,  112 . In this case, the controller  15  may detect activation of a touch sensitive area  20 ,  22  and only activate the one or two piezoelectric elements  106 ,  108 ,  110 ,  112  that are closest to the activated touch sensitive area  20 ,  22 . 
     The claimed touch sensitive LCD module  12  is a significant improvement over prior art devices on a number of different levels. For example, the LCD glasses  14  could be mounted using flexible materials inside the bezel of the touch sensitive LCD module  12 . In this case, the flexible mount effectively isolates the housing from vibration of the LCD glasses  14  caused by the piezoelectric elements  106 ,  108 ,  110 ,  112 . As such, activation of the piezoelectric elements  106 ,  108 ,  110 ,  112  is only felt on the LCD galsses  14  and not on the bezel of display module and overall phone housing  11 . 
     Prior art methods of providing haptics for activation of touch sensitive areas have relied upon a call alerting motor that shakes the entire device  10 . Since the LCD display  14  floats within the bezel of the touch sensitive LCD module  12 , the vibrational haptics from the piezoelectric elements  106 ,  108 ,  110 ,  112  are not felt through the housing of the device  10 , but only by the finger of the user that is in contact with a touch sensitive area  20 ,  22 . 
     Human factor studies have suggested that localized haptics (i.e., tactile feedback where a user touches the touch sensitive LCD module  12 ) is a much more compelling experience. Not only is the experience more compelling, but the availability of immediate feedback reduces errors because the user is immediately alerted that a selection has been accepted by the device  10 . 
     A specific embodiment of method and apparatus for providing keyboard haptics has been described for the purpose of illustrating the manner in which the invention is made and used. It should be understood that the implementation of other variations and modifications of the invention and its various aspects will be apparent to one skilled in the art, and that the invention is not limited by the specific embodiments described. Therefore, it is contemplated to cover the present invention and any and all modifications, variations, or equivalents that fall within the true spirit and scope of the basic underlying principles disclosed and claimed herein.