Abstract:
Data acquisition from a touch-surface input unit may be disrupted during the generation of radio frequency (“RF”) pulses. To mitigate this problem, touch-surface data acquisition is temporarily halted during RF pulse generation. Data collected prior to temporarily halting is retained, with subsequently acquired data being added to prior collected data.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 11/620,466, filed Jan. 5, 2007, the entire disclosure of which is incorporated herein by reference. 
         [0002]    The subject matter claimed herein is related to the subject matter described in U.S. patent application Ser. Nos. 10/840,862 entitled “Multipoint Touchscreen” by Steve Hotelling and Brian Huppi (filed 6 May 2004), 11/278,080 entitled “Force Imaging Input Device and System” by Steve Hotelling and Brian Huppi (filed 30 Mar. 2006) and 11/382,402 entitled “Force and Location Sensitive Display” by Steve Hotelling (filed 9 May 2006), all of which are hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0003]    The invention relates generally to power consumption and noise mitigation techniques for electronic devices. More particularly, but not by way of limitation, the invention relates to reducing or avoiding operational problems caused by power droops and electrical interference during touch-surface data acquisition operations in portable electronic devices that generate radio frequency (“RF”) pulses. 
         [0004]    The use of touch pads and touch screens (collectively “touch-surfaces”) has become increasingly popular in electronic systems because of their ease of use and versatility of operation. In general, these systems employ a two dimensional grid or array of sensing elements. Each sensing element (aka “pixel”) generates an output signal indicative of the electric field disturbance (for capacitance sensors), force (for pressure sensors) or optical coupling (for optical sensors) at the sensor element. The ensemble of pixel values represents an “image.” 
         [0005]    In portable electronic devices such as mobile telephones and personal digital assistants (“PDA”) that use a touch-surface for user input and that also generate radio frequency (“RF’) pulses for communication, there is a problem in that touch-surface data acquisition cannot reliably or accurately occur during RF pulse transmission. This is primarily due to two factors. First, the power required to generate a RF pulse can cause a voltage drop large enough to interfere with the normal operation of a touch-surface&#39;s data acquisition circuitry. Second, the resulting RF pulse can generate sufficient electrical noise to interfere with the acquisition of touch-surface data. 
         [0006]    Another complicating factor in devices of this type is the need to generate RF pulses at a rate that is more frequent than the time it takes to capture a complete image from the touch-surface. By way of example, mobile telephones conforming to the Global System for Mobile Communications specification (e.g., GSM 05.01, version 8.4.0) transmit RF pulses approximately every 4.6 milliseconds, with each pulse lasting 577 microseconds for voice transmission or 1,154 microseconds for data transmission. Touch-surface image acquisition operations, however, may take more the inter-pulse duration allowed by such specifications. Thus, it would be beneficial to provide a means to mitigate the operational interference to touch-surface data acquisition operations in portable electronic devices that generate RF pulses. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    In one embodiment, the invention provides a method to acquire touch-surface sensor data from a portable radio frequency (“RF”) capable electronic device. The method includes acquiring data from a first set of sensors associated with the touch-surface (e.g., a first row of pixel data), recording the data if a RF pulse is not detected during the act of acquiring and otherwise discarding the data and repeating the act of acquiring after the RF pulse terminates, and the acts of acquiring and recording for a second set of sensors associated with the touch-surface. In one embodiment, the acts of acquiring and recording are initiated for successive sets of touch-surface sensors at regular intervals. In another embodiment, the acts of acquiring and recording are initiated a specified time period after the act of recording is completed. Methods in accordance with the invention may be stored in any media that is readable and executable by a computer system. In addition, the described method may be incorporated in any portable electronic device capable of providing RF-based communication (e.g., voice and/or data communication). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIGS. 1A-1C  show a portable electronic device in accordance with one embodiment of the invention. 
           [0009]      FIG. 2  shows, in block diagram form, an electronic device in accordance with one embodiment of the invention. 
           [0010]      FIG. 3  shows, in flowchart form, a frame acquisition method in accordance with one embodiment of the invention. 
           [0011]      FIGS. 4A and 4B  show frame acquisition time lines in accordance with the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0012]    The following description is presented to enable any person skilled in the art to make and use the invention as claimed and is provided in the context of the particular examples discussed below (e.g., a mobile telephone conforming to the Global System for Mobile Communications specifications), variations of which will be readily apparent to those skilled in the art. Accordingly, the claims appended hereto are not intended to be limited by the disclosed embodiments, but are to be accorded their widest scope consistent with the principles and features disclosed herein. 
         [0013]    Referring to  FIG. 1A , portable electronic device  100  in accordance with one embodiment of the invention comprises body or case  105 , touch-surface  110  and antenna  115 . In accordance with this embodiment, touch-surface  110  covers substantially all of device  100 &#39;s front surface, uses mutual capacitance sensing elements arranged in a two-dimensional grid and is capable of detecting multiple simultaneous contacts. Antenna  115  is used to transmit and receive information in accordance with Global System for Mobile Communications standards. 
         [0014]    Referring to  FIG. 1B , in one operational mode electronic device  100  may provide mobile phone functionality. In this mode, touch-surface  110  is used to display soft-keys  120  (e.g., a standard alphanumeric telephone keypad), accept user input (e.g., finger or stylus contact), and to display user feedback  125  (e.g., previously selected soft-keys). Referring to  FIG. 1C , in another mode electronic device  100  may provide music and/or video playback functionality. In this mode, touch-surface  110  is used to display audio/video playback control soft-keys  130  (e.g., MENU, skip forward, skip backward, pause and play soft-keys), accept user input (e.g., finger or stylus contact), and to display playback information  135  (e.g., menu items, song title, album cover art, volume control and/or current play position). In still another embodiment, electronic device  100  may provide web browsing functionality. Here, touch-surface  110  is used to display web page manipulation soft-keys  130  (e.g., refresh, go back, go forward, close and URL entry. It will be recognized that electronic device  100  may also provide additional capability such as, for example, address book and calendar functionality. 
         [0015]    Referring to  FIG. 2 , electronic device  200  in accordance with one embodiment of the invention comprises mutual capacitance touch-surface component  205 , power source  210 , other circuitry  215  and antenna  220 . Power circuit  210  provides the energy necessary to power touch-surface component  205 , other circuitry  215  and the transmission of RF signals via antenna  220 . Other circuitry  215  typically includes one or more computer processors, memory and RF transmission and receiving circuitry. 
         [0016]    In capacitive touch-surfaces such as that shown in  FIG. 2  (e.g.,  205 ), a first set of conductive traces run in a first direction (e.g., rows R 1  to RM) and are insulated by a dielectric insulator from a second set of conductive traces running in a second direction (e.g., columns Cl to CN). Grid  225  formed by the overlapping conductive traces create an M×N array of capacitors that can store electrical charge. Each capacitive sensing element is referred to as a pixel, e.g., pixel  230 . When an object such as a stylus or finger is brought into proximity or contact with array  225 , the capacitance of the pixels at that location change. This change can be used to identify the location of the touch event. (Touch-surface component  205  may also detect the force applied to its surface.) In practice, circuit  235  drives one (or a few) rows of array  225  at a time and circuit  240  captures signal values indicative of the pixels in the driven row(s). When this operation is complete for a first row (or group of rows), circuit  235  drives a next row (or group of rows) and circuit  240  captures pixel values associated with the newly driven row(s). This process is repeated, under control of circuit  245 , until all pixel values in array  225  have been captured. The ensemble of pixel values is referred to as an image or frame (e.g., frame  250 ). 
         [0017]    It has been found that in some RF generating portable electronic devices, operational voltage from power source  210  (e.g., a battery) to a touch-surface component  205  can drop sufficiently low during RF pulse transmission to interfere with the reliable acquisition of frame data (e.g., the accurate reading of pixel data). It has further been found that electrical noise attributable to the transmission of an RF signal can cause frame acquisition errors due to the increased electrical current required for RF transmission. Thus, it would be beneficial to avoid acquiring touch-surface frame data during RF signal transmission. 
         [0018]    For proper operation and to ensure a responsive user interface however, a frame should be obtained frequently (e.g., every 5 to 20 milliseconds). In many RF-capable electronic devices, however, it may be necessary to transmit RF signals too frequently to permit a frame from being acquired all at once without colliding with RF pulse transmission. For example, the Global System for Mobile Communications standard 05.01, version 8.4.0, requires that an RF pulse be transmitted approximately every 4.6 milliseconds, with voice being encoded in 577 microsecond bursts and data being encoded in 1,154 microsecond bursts (leaving between approximately 3.4 to 4.0 milliseconds between successive RF pulses). To mitigate against these operational requirements, a method in accordance with the invention holds off acquiring touch-surface frame data during RF signal transmission. 
         [0019]    Referring to  FIG. 3 , in one embodiment of the invention touch-surface frame acquisition  300  is performed on a row-by-row basis. To begin, a first row of sensors from among the plurality of rows in a sensor matrix is identified (block  305 ). A test is then made to determine if a RF pulse is currently being generated (block  310 ). If a RF pulse is being generated (the “Yes” prong of block  310 ), frame/row data acquisition is postponed. If no RF pulse is detected (the “No” prong of block  310 ), data is acquired from the identified row of touch-surface sensors (block  315 ). Following acquisition, another check is made to determine if a subsequent or next RF pulse was transmitted at any time during the acts of block  315  (block  320 ). If such a RF pulse was detected (the “Yes” prong of block  320 ), the “just acquired” sensor data is discarded (block  325 ) and processing continues at block  310 . That is, if the row of pixels just captured did not complete before the start of a subsequent RF pulse, the row is discarded. As used herein, a row of pixel data is “complete” if the row&#39;s pixel values are detected (and, typically, digitized) and stored to a memory (typically buffer memory associated with circuit  240 ) before a RF pulse is detected. If no RF pulse is detected (the “No” prong of block  320 ), a check is made to determine if a complete frame has been collected (block  330 ). If a complete frame has not been acquired (the “No” prong of block  330 ), the next row of sensors is identified (block  335 ) whereafter processing continues at block  310 . If a complete frame has been acquired (the “Yes” prong of block  330 ), data acquisition begins anew for the next frame (block  340 ). 
         [0020]    Two frame acquisition operations in accordance with  FIG. 3  are of interest. The first is when frame acquisition onset occurs simultaneously with RF pulse generation (see  FIG. 4A ). The second is when frame acquisition onset occurs immediately following RF pulse generation (see  FIG. 4B ). In each of  FIGS. 4A and 4B , T (SAMPLE)  refers to the frame acquisition sample period, T (ACQUIRE)  refers to the time actually required to capture a frame, T (RF)  refers to the RF pulse period and T (PULSE)  refers to the duration of each RF pulse. For illustrative purposes only, T (SAMPLE) , T (ACQUIRE) , T (RF)  and T (PULSE)  for electronic devices conforming to the Global System for Mobile Communications specification (e.g., GSM 05.01, version 8.4.0) are as follows: T (RF) −4.6 milliseconds; and T (PULSE) −0.577 milliseconds (voice) or −1.1 milliseconds (data). For the purpose of this description, T (SAMPLE)  will be taken as approximately 14 milliseconds and T (ACQUIRE)  will be taken as approximately 7 milliseconds. 
         [0021]    Referring to  FIG. 4A , if frame acquisition onset coincides with RF pulse generation at time T( 0 ), frame acquisition is delayed until RF pulse generation completes at time T( 1 ). Frame acquisition then continues until time T( 2 ) when another RF pulse is generated. As shown, this process repeats until a complete frame is acquired at time T( 6 ). See also  FIG. 3 . Accordingly, T (ACQUIRE) =[T( 2 )−T( 1 )]+[T( 4 )−T( 3 )]+[T( 6 )−T( 5 )]. Referring now to  FIG. 4B , if frame acquisition onset immediately follows completion of a RF pulse, at time T( 0 ), it will continue until RF pulse generation begins again at time T( 1 ). Frame acquisition begins again at time T( 2 ) following completion of RF pulse generation. As shown, this process repeats until a complete frame is acquired at time T( 5 ). In this scenario, T(ACQUIRE)=[T( 1 )−T( 0 )]+[T( 3 )−T( 2 )]+[T( 5 )−T( 4 )]. 
         [0022]    Referring again to  FIG. 3 , in one embodiment acts in accordance with block  340  begin a specified sample period after the completion of acts in accordance with block  330 . That is, there is at least a specified period between the time a first frame is completely acquired and initiating the acquisition of the next or subsequent frame. For example, in  FIG. 4A  this approach would initiate a new frame acquisition operation no sooner than the time [T( 6 )+T (SAMPLE) ]. In  FIG. 4B , a new frame acquisition operation would begin no sooner than the time [T( 5 )+T (SAMPLE) ]. In another embodiment, acts in accordance with block  340  are performed as soon after a prior frame is acquired as permitted, but no sooner than a specified period of time after the prior frame was scheduled to begin. In  FIG. 4A  this approach would initiate a new frame acquisition operation no sooner than the time T (SAMPLE)  after time T( 0 )−delaying only if another RF pulse coincides with the scheduled onset of frame acquisition operations. Similarly, in  FIG. 4B  a new frame acquisition operation would begin no sooner than the time T (SAMPLE) . 
         [0023]    With respect to  FIGS. 4A and 4B , it will be recognized by one of ordinary skill in the art that frame acquisition operations cannot actually be initiated simultaneously with cessation of RF pulse generation. There is generally a short time between when an RF pulse begins and ends and when these events can be detected. In practice, “detection” times are small and, for convenience, have been omitted from  FIGS. 4A and 4B . 
         [0024]    Various changes in the materials, components, circuit elements, as well as in the details of the illustrated operational method are possible without departing from the scope of the following claims. For instance, it will be recognized by those of ordinary skill in the art, that the inventive concept described herein is not limited to the device configuration illustrated in  FIGS. 1A-1C . For example, electronic device  100  may include: additional keys or buttons (e.g., an on/off button); an internal (rather than an external) antenna; a touch-surface that does not take up substantially all of the device&#39;s top surface; a touch-surface that is not capable of detecting multiple simultaneous contacts; a touch-surface that is capable of detecting both touch and force; and a touch-surface utilizing sensor elements other than capacitors (e.g., a pressure or optically-based touch-surface). It will also be recognized that detection of RF pulse generation may be made in any number of ways. For example, a control signal from RF generation circuitry in circuit  215  may indicate when an RF pulse is being transmitted and when it is not being transmitted. In another embodiment, a common clock signal may be used to generate RF pulses and indicate when such pulses are being generated. In still another embodiment, frame acquisition may acquire multiple rows simultaneously. In this case, the multiple-rows may be treated as a single row for purposes of method  300 . In yet another embodiment, frame acquisition may employ multiple samples. For example, acquisition of a single row may entail two or more separate samples each at a different frequency. In addition, acts in accordance with  FIG. 3  may be performed by a programmable control device executing instructions organized into one or more program modules. A programmable control device may be a single computer processor, a special purpose processor (e.g., a digital signal processor, “DSP”), a plurality of processors coupled by a communications link or a custom designed state machine. Custom designed state machines may be embodied in a hardware device such as an integrated circuit including, but not limited to, application specific integrated circuits (“ASICs”) or field programmable gate array (“FPGAs”). Storage devices suitable for tangibly embodying program instructions include, but are not limited to: magnetic disks (fixed, floppy, and removable); optical media such as CDROMs and digital video disks (“DVDs”); and semiconductor memory devices such as Electrically Programmable Read-Only Memory (“EPROM”), Electrically Erasable Programmable Read-Only Memory (“EEPROM”), Programmable Gate Arrays and flash devices.