PATENT DOCUMENT

Publication Number: US-10185443-B2
Application Number: US-201514868125-A
Country: US
Kind Code: B2

Title: Touch sensing error compensation

Abstract:
Error compensation of a touch sensing signal is provided. A touch screen can include a drive region that can be driven by a drive signal, and a sense region that can output a sense signal that includes information of a first amount of touch on or near the touch screen and information of a first amount of error. The first amount of touch can be based on the drive signal. The touch screen can include a compensation sensor that can output a compensation signal that includes information of a second amount of error, and an error compensator that can compensate for the first amount of error in the sense signal based on the second amount of error.

Claims:
What is claimed is: 
     
       1. A touch screen comprising:
 a drive region configured to be driven by a drive signal; 
 a sense region disposed adjacent to the drive region, the sense region configured to output a sense signal that includes information of a first amount of touch on or near the touch screen and information of a first amount of error, wherein the first amount of touch is based on the drive signal; 
 a compensation sensor disposed between the drive region and the sense region, the compensation sensor configured to output a compensation signal that includes information of a second amount of error, wherein the second amount of error is based on the drive signal; and 
 an error compensator configured to extract the second amount of error from the compensation signal and to compensate for the first amount of error in the sense signal based on the extracted second amount of error obtained from the compensation signal. 
 
     
     
       2. The touch screen of  claim 1 , wherein the compensation signal further includes information of a second amount of touch based on the drive signal, a ratio of the second amount of touch to the second amount of error not exceeding a ratio of the first amount of touch to the first amount of error. 
     
     
       3. The touch screen of  claim 2 , wherein the drive region includes a first conductive line in a first direction, the sense region includes a second conductive line in a second direction transverse to the first direction, the compensation sensor includes a third conductive line, the information of the first amount of touch is based on a change in a capacitance between first and second conductive lines, and the information of the second amount of touch is based on a change in a capacitance between the first and third conductive lines. 
     
     
       4. The touch screen of  claim 1 , wherein the error source includes one of an average display pixel luminance, a local temperature, and an amount of ambient light. 
     
     
       5. The touch screen of  claim 1 , wherein the drive region includes a first conductive line in a first direction, the sense region includes a second conductive line in a second direction transverse to the first direction, and the information of the first amount of touch is based on a change in a capacitance between first and second conductive lines. 
     
     
       6. The touch screen of  claim 1 , further comprising:
 a plurality of sense regions; and 
 a plurality of compensation sensors, 
 wherein each compensation sensor is disposed between two sense regions. 
 
     
     
       7. The touch screen of  claim 1 , wherein the information of the second amount of error is based on the drive signal. 
     
     
       8. The touch screen of  claim 7 , further comprising:
 a circuit capacitively coupled to the drive region, such that a first portion of the drive signal is coupled into the circuit, 
 wherein the circuit is further capacitively coupled to each of the sense region and the compensation sensor, such that the information of the first amount of error is based on a second portion of the first portion of the drive signal coupled into the sense region from the circuit, and the information of the second amount of error is based on a third portion of the first portion of the drive signal coupled into the compensation sensor from the circuit. 
 
     
     
       9. The touch screen of  claim 8 , wherein the circuit includes a portion of a display system that displays images on the touch screen. 
     
     
       10. The touch screen of  claim 9 , wherein the circuit includes a gate line of the display system. 
     
     
       11. The touch screen of  claim 1  wherein:
 the error compensator is configured to subtract the compensation signal from the sense signal; and 
 the compensation sensor and the sense region are configured to concurrently detect the compensation signal and the sense signal, respectively. 
 
     
     
       12. The touch screen of  claim 1 , wherein the first amount of error and the second amount of error are introduced by an error source within the touch screen. 
     
     
       13. A method of compensating for error in a touch sensing signal, the method comprising:
 obtaining the touch sensing signal from a sense region disposed adjacent to a drive region, the touch sensing signal including information of a first amount of touch and information of a first amount of error, wherein the first amount of touch is based on a drive signal driving the drive region; 
 obtaining a compensation signal from a compensation sensor disposed between the drive region and the sense region, the compensation signal including information of a second amount of error, wherein the second amount of error is based on the drive signal; 
 extracting the second amount of error from the compensation signal; and 
 compensating for the first amount of error in the touch sensing signal based on the extracted second amount of error obtained from the compensation signal. 
 
     
     
       14. The method of  claim 13 , wherein the compensation signal further includes second information of an amount of touch, and a ratio of the second amount of touch to the second amount of error does not exceed a ratio of the first amount of touch to the first amount of error. 
     
     
       15. The method of  claim 13 , wherein obtaining the touch sensing signal includes driving drive regions of a touch screen with drive signals and obtaining the touch sensing signal from one or more sense regions of the touch screen, the method further comprising:
 obtaining information of a state of a display system that displays an image on the touch screen; 
 determining if the state information satisfies a first criteria; and 
 in accordance with a determination that the state information satisfies the first criteria, determining the second amount of error based on a predetermined value of error independent of the information of the second amount of error of the compensation signal, wherein compensating for the first amount of error is based on the predetermined value of error. 
 
     
     
       16. The method of  claim 15 , wherein the state information includes one of an average display pixel luminance, a local temperature, and an amount of ambient light. 
     
     
       17. The method of  claim 15 , further comprising:
 in accordance with a determination that the state information does not satisfy the first criteria, calibrating the predetermined value of error based on the information of the second amount of error obtained from the compensation signal. 
 
     
     
       18. The method of  claim 16 , wherein the state information includes a plurality average display pixel luminances, and the first criteria is based on a difference in average display pixel luminances of two regions of display pixels of the touch screen. 
     
     
       19. The method of  claim 13 , wherein the first amount of error is based on the drive signal. 
     
     
       20. The method of  claim 13 , wherein:
 compensating for the first amount of error in the touch sensing signal based on the second amount of error in the compensation signal comprises subtracting the compensation signal from the sense signal; and 
 obtaining the touch sensing signal occurs concurrently with obtaining the compensation signal. 
 
     
     
       21. The method of  claim 13 , wherein the first amount of error and the second amount of error are introduced by an error source within the touch screen.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. Non-Provisional application Ser. No. 12/877,061, filed Sep. 7, 2010 (Publication No. 2011-0298746, published Dec. 8, 2011), which claims the benefit of Provisional Application No. 61/352,310, filed Jun. 7, 2010, the contents of which are incorporated by reference herein in their entirety for all purposes. 
    
    
     FIELD OF THE DISCLOSURE 
     This relates generally to touch sensing, and more particularly, compensating for errors in touch sensing. 
     BACKGROUND OF THE DISCLOSURE 
     Many types of input devices are presently available for performing operations in a computing system, such as buttons or keys, mice, trackballs, joysticks, touch sensor panels, touch screens and the like. Touch screens, in particular, are becoming increasingly popular because of their ease and versatility of operation as well as their declining price. Touch screens can include a touch sensor panel, which can be a clear panel with a touch-sensitive surface, and a display device such as a liquid crystal display (LCD) that can be positioned partially or fully behind the panel so that the touch-sensitive surface can cover at least a portion of the viewable area of the display device. Touch screens can allow a user to perform various functions by touching the touch sensor panel using a finger, stylus or other object at a location often dictated by a user interface (UI) being displayed by the display device. In general, touch screens can recognize a touch and the position of the touch on the touch sensor panel, and the computing system can then interpret the touch in accordance with the display appearing at the time of the touch, and thereafter can perform one or more actions based on the touch. In the case of some touch sensing systems, a physical touch on the display is not needed to detect a touch. For example, in some capacitive-type touch sensing systems, fringing fields used to detect touch can extend beyond the surface of the display, and objects approaching near the surface may be detected near the surface without actually touching the surface. 
     Capacitive touch sensor panels can be formed from a matrix of drive and sense lines of a substantially transparent conductive material, such as Indium Tin Oxide (ITO), often arranged in rows and columns in horizontal and vertical directions on a substantially transparent substrate. It is due in part to their substantial transparency that capacitive touch sensor panels can be overlaid on a display to form a touch screen, as described above. Some touch screens can be formed by integrating touch sensing circuitry into a display pixel stackup (i.e., the stacked material layers forming the display pixels). 
     SUMMARY 
     The following description includes examples of compensating for errors that can occur in touch sensing due to various error mechanisms. In one example embodiment, a compensation sensor can be included in a touch sensing device. The characteristics of the compensation sensor, such as size, shape, location in the device, electrical connections, material composition, etc., can be selected such that the compensation sensor can satisfy two criteria. First, the compensation sensor can provide information about the error in touch sensing. Second, in proportion to the relative sensitivities to the error of the compensation and touch sensors, the compensation sensor can be less sensitive to touch than the touch sensor. In this way, the error in the touch sensing signal can be compensated by, for example, subtracting the compensation signal from the touch sensing signal in some predetermined ratio. 
     In some embodiments, a touch screen can include a drive region that is driven by a drive signal, a sense region that outputs a sense signal that includes information of a first amount of touch on or near the touch screen and information of a first amount of error, the first amount of touch being based on the drive signal, and a compensation sensor that outputs a compensation signal that includes information of a second amount of error. An error compensator can compensate for the first amount of error in the sense signal based on the second amount of error. 
     In another example, an amount of error introduced into a touch sensing signal by a known and/or controlled error source can be measured over a range of values of the error source to produce, for example, a list including a predetermined error value for each of the range of values of the error source. For example, if it is known that an amount of error introduced into the touch sensing signal of a touch pixel of a touch screen depends on a state of the touch screen, such as the average luminance values of the display pixels in the touch pixel, the amount of error may be measured at different values of average luminance, and stored in a look-up table (LUT) in a computer-readable medium of the device. For example, it can be determined whether a difference in average luminance values of two or more regions of display pixels satisfies a first criteria. For example, a large difference in luminance between particular regions could indicate that a particular “worst-case” image is currently being displayed, the worst-case image being an image that has been determined to affect the accuracy of an error compensation based on the compensation signal. In some embodiments, if a worst-case image is determined, error compensation can be based on a predetermined error value, for example. In this way, it can be possible to provide error compensation without the need for a compensation sensor that is coupled to the same or similar error mechanism as the touch sensor and having proportionately less touch sensitivity than the touch sensor, which can be beneficial in situations in which the particular error mechanism is unknown, which can make design and implementation of a compensation sensor more difficult. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1C  illustrate an example mobile telephone, an example media player, and an example personal computer that each include an example touch screen according to embodiments of the disclosure. 
         FIG. 2  is a block diagram of an example computing system that illustrates one implementation of an example touch screen according to embodiments of the disclosure. 
         FIG. 3  is a more detailed view of the touch screen of  FIG. 2  showing an example configuration of drive lines and sense lines according to embodiments of the disclosure. 
         FIG. 4  illustrates an example configuration in which touch sensing circuitry includes common electrodes (Vcom) according to embodiments of the disclosure. 
         FIG. 5  illustrates an exploded view of example display pixel stackups according to embodiments of the disclosure. 
         FIG. 6  illustrates an example touch sensing operation according to embodiments of the disclosure. 
         FIG. 7  illustrates a portion of an example touch screen during a touch sensing phase according to embodiments of the disclosure. 
         FIG. 8  illustrates a model of an example error mechanism in an example touch screen according to embodiments of the disclosure. 
         FIG. 9  illustrates a model of another example error mechanism in an example touch screen according to embodiments of the disclosure. 
         FIG. 10  illustrates a circuit diagram of a drive-sense operation of an example touch screen according to embodiments of the disclosure. 
         FIG. 11  illustrates a flowchart of an example method of compensating for error using predetermined error compensation values in touch measurement according to embodiments of the disclosure. 
         FIG. 12  illustrates a portion of an example touch screen including compensation regions according to embodiments of the disclosure. 
         FIG. 13  illustrates a portion of an example touch screen during a touch sensing phase according to embodiments of the disclosure. 
         FIG. 14  illustrates example error mechanisms in an example touch screen according to embodiments of the disclosure. 
         FIG. 15  illustrates other example error mechanisms in an example touch screen according to embodiments of the disclosure. 
         FIG. 16  illustrates an example touch screen configuration according to embodiments of the disclosure. 
         FIG. 17  illustrates another example touch screen configuration according to embodiments of the disclosure. 
         FIG. 18  illustrates a circuit diagram of a drive-sense operation of an example touch screen according to embodiments of the disclosure. 
         FIG. 19  illustrates a flowchart of an example method of compensating for error in touch measurement using compensation sensors according to embodiments of the disclosure. 
         FIG. 20  illustrates an example touch screen configuration according to embodiments of the disclosure. 
         FIG. 21  illustrates another example touch screen configuration according to embodiments of the disclosure. 
         FIG. 22  illustrates a flowchart of an example method of compensating for error in touch measurement using a combination of predetermined error compensation values and compensation sensors according to embodiments of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description of example embodiments, reference is made to the accompanying drawings which form a part hereof, and in which it is shown by way of illustration specific embodiments in which embodiments of the disclosure can be practiced. It is to be understood that other embodiments can be used and structural changes can be made without departing from the scope of the embodiments of this disclosure. 
     The following description includes examples in which errors in touch sensing due to various error mechanisms can be compensated. Touch sensing circuitry in devices such as touch panels, touch screens, etc., can be exposed to various sources of error that can enter the touch sensing system through various error mechanisms. For example, touch sensing circuitry can operate alongside other types of circuitry, such as in a touch screen formed by a touch panel overlay on a display screen. Close proximity of touch and display circuitry may cause undesirable interference with touch sensing. Other sources of error can include temperature, ambient light, non-uniformity of construction during manufacture (particularly gradually changing non-uniformities, such as, for example, dielectric thickness non-uniformity, mobility of TFT gradient across the mother glass, etc.), degradation of components due to age, etc. Sources of error can enter the touch sensing system through mechanisms. For example, a localized change in the temperature of a touch screen may change a capacitance of a transistor of a display system, which may increase an undesired capacitive coupling in a touch sensing system. In another example, a display system of a touch screen may change a voltage across a liquid crystal cell to display an image, but the voltage change can cause the dielectric constant of the liquid crystal to change in a way that introduces error in the touch sensing system. 
     Errors in touch sensing can include any portion of a touch sensing measurement that does not carry information about touch. A touch sensing signal output from a touch sensor can be a composite signal, for example, that includes one or more signals caused by a touch, and carrying touch information about the touch, and one or more signals caused by other sources, such as electrical interference, crosstalk, etc., that do not provide information about the touch. Some error sources can cause a change in the operation of touch sensing that causes the portion of the touch sensing signal that carries touch information to inaccurately reflect the amount of touch. For example, an error source could cause a drive signal to be generated with an abnormally high voltage, which could result in the sense signal sensing a touch to be abnormally high as well. Thus, a portion of the touch information itself could include an error. 
     As touch sensing circuitry becomes more closely integrated with circuitry of other systems, undesirable interaction between circuit elements of different systems can be more likely to occur. For example, touch sensing circuitry can be integrated into the display pixel stackups of integrated touch screens. Display pixel stackups are typically manufactured by processes including depositing, masking, etching, doping, etc., of materials such as conductive materials (e.g., metal, substantially transparent conductors), semiconductive materials (e.g., polycrystalline silicon (Poly-Si)), and dielectric materials (e.g., SiO2, organic materials, SiNx). Various elements formed within a display pixel stackup can operate as circuitry of the display system to generate an image on the display, while other elements can operate as circuitry of a touch sensing system that senses one or more touches on or near the display. 
     The following description includes examples in which the errors in touch sensing introduced through various error mechanisms can be compensated. In one example, a compensation sensor can be included in a touch sensing device. The characteristics of the compensation sensor, such as size, shape, location in the device, electrical connections, material composition, etc., can be selected such that the compensation sensor can satisfy two criteria. First, the compensation sensor can provide information about the error in touch sensing. For example, the compensation sensor can be coupled to the same or similar error mechanism as a touch sensor of the device, such that a compensation signal output by the compensation sensor can be affected by the same or similar error as the touch sensing signal output by the touch sensor. Second, in proportion to the relative sensitivities to the error of the compensation and touch sensors, the compensation sensor can be less sensitive to touch than the touch sensor. In other words, the compensation sensor can measure a higher ratio of error to touch than the touch sensor. In this way, the error in the touch sensing signal can be compensated by, for example, subtracting the compensation signal from the touch sensing signal in some predetermined ratio. The predetermined ratio can be based on a number of factors, such as relative sizes of the compensation and touch sensors, the particular error mechanism or mechanisms, etc. The ratio can be determined empirically, for example, and stored in a computer-readable medium of the device. In some examples, the ratio can vary depending on a number of operational factors, and in these examples, a range of ratio values can be stored, and the appropriate ratio value can be selected for an error compensation operation. Using one or more compensation sensors in this way can, for example, provide a real-time measurement of one or more errors being introduced into a touch sensing signal. 
     In another example, an amount of error introduced into a touch sensing signal by a known and/or controlled error source can be measured over a range of values of the error source to produce, for example, a list including a predetermined error value for each of the range of values of the error source. For example, if it is known that an amount of error introduced into the touch sensing signal of a touch pixel of a touch screen depends on the average luminance values of the display pixels in the touch pixel, the amount of error may be measured at different values of average luminance, and stored in a look-up table (LUT) in a computer-readable medium of the device. This process may be performed once, for example, during a device calibration at the factory. During operation, the device can scan the frame buffer, which can contain the current luminance values of the display pixels, read out the luminance values for a particular touch pixel, determine the average luminance for the touch pixel, read the corresponding error value from the LUT, and compensate the current touch sensing signal of the touch pixel with the read-out error value. In this example, it may not be necessary that the particular error mechanism by which the luminance of the display pixels introduces error in the touch sensing signal is known, so long as an amount of error resulting from the luminance values can be determined. In this way, it can be possible to provide error compensation without the need for a compensation sensor that is coupled to the same or similar error mechanism as the touch sensor and having proportionately less touch sensitivity than the touch sensor, which can be beneficial in situations in which the particular error mechanism is unknown, which can make design and implementation of a compensation sensor more difficult. 
     Luminance values of display pixels are an example of a controlled (and therefore known) error source, because the device itself controls the luminance values. In some example embodiments, error sources can be known, but not controlled. For example, it may be known that the temperature of the display pixels of a touch pixel of a touch screen can introduce different errors over a range of temperature values. Even though the particular error mechanism causing the temperature-dependent error may not be known, it can be possible to include one or more temperature sensors in the touch screen to allow the temperature values of the touch pixels to be measured and known during operation. Similar to the preceding example, a LUT storing predetermined error values measured during a calibration process at different temperatures can be used to compensate for errors resulting from temperature variance. As in the preceding example, it may not be necessary to include a compensation sensor coupled to the same or similar error mechanism as the touch sensor and having proportionately less touch sensitivity than the touch sensor. 
     In some example embodiments, a combination of one or more compensation sensors and predetermined-stored error values can be used. For example, compensation sensors can be used to compensate for error related to one type of error source, while predetermined error values can be used to compensate for error related to another type of error source. In some example embodiments, compensation sensors and predetermined error values can be used to compensate for the same type of error, for example, by combining the two types of error compensation, by averaging, for example. In some example embodiments, one or the other of the two types of compensation can be used to compensate a given touch sensing signal. In one touch screen embodiment, for example, compensation sensors can be positioned in a touch screen to sense error related to display pixel luminance. However, there may be some images for which the particular arrangement of luminances makes it difficult for the compensation sensors to accurately sense the error. If these worst-case images are known, the luminance-dependent errors may be predetermined at the factory, for example, for the worst-case images and stored in a LUT. During operation, the compensation sensors can be used unless the device displays a worst-case image, in which case the device can switch to the predetermined error LUT for compensation information. 
     Although example embodiments are described below in relation to integrated touch screens, other types of touch sensing arrangements can be used, for example, non-integrated touch screens, touchpads, etc. 
       FIGS. 1A-1C  show example systems in which a touch screen according to embodiments of the disclosure may be implemented.  FIG. 1A  illustrates an example mobile telephone  136  that includes a touch screen  124 .  FIG. 1B  illustrates an example digital media player  140  that includes a touch screen  126 .  FIG. 1C  illustrates an example personal computer  144  that includes a touch screen  128 . Touch screens  124 ,  126 , and  128  may be based on, for example, self capacitance or mutual capacitance, or another touch sensing technology. For example, in a self capacitance based touch system, an individual electrode with a self-capacitance to ground can be used to form a touch pixel for detecting touch. As an object approaches the touch pixel, an additional capacitance to ground can be formed between the object and the touch pixel. The additional capacitance to ground can result in a net increase in the self-capacitance seen by the touch pixel. This increase in self-capacitance can be detected and measured by a touch sensing system to determine the positions of multiple objects when they touch the touch screen. A mutual capacitance based touch system can include, for example, drive regions and sense regions, such as drive lines and sense lines. For example, drive lines can be formed in rows while sense lines can be formed in columns (e.g., orthogonal). Touch pixels can be formed at the intersections of the rows and columns. During operation, the rows can be stimulated with an AC waveform and a mutual capacitance can be formed between the row and the column of the touch pixel. As an object approaches the touch pixel, some of the charge being coupled between the row and column of the touch pixel can instead be coupled onto the object. This reduction in charge coupling across the touch pixel can result in a net decrease in the mutual capacitance between the row and the column and a reduction in the AC waveform being coupled across the touch pixel. This reduction in the charge-coupled AC waveform can be detected and measured by the touch sensing system to determine the positions of multiple objects when they touch the touch screen. In some embodiments, a touch screen can be multi-touch, single touch, projection scan, full-imaging multi-touch, or any capacitive touch. 
       FIG. 2  is a block diagram of an example computing system  200  that illustrates one implementation of an example touch screen  220  according to embodiments of the disclosure. Computing system  200  could be included in, for example, mobile telephone  136 , digital media player  140 , personal computer  144 , or any mobile or non-mobile computing device that includes a touch screen. Computing system  200  can include a touch sensing system including one or more touch processors  202 , peripherals  204 , a touch controller  206 , and touch sensing circuitry (described in more detail below). Peripherals  204  can include, but are not limited to, random access memory (RAM) or other types of memory or storage, watchdog timers and the like. Touch controller  206  can include, but is not limited to, one or more sense channels  208 , channel scan logic  210  and driver logic  214 . Channel scan logic  210  can access RAM  212 , autonomously read data from the sense channels and provide control for the sense channels. In addition, channel scan logic  210  can control driver logic  214  to generate stimulation signals  216  at various frequencies and phases that can be selectively applied to drive regions of the touch sensing circuitry of touch screen  220 , as described in more detail below. In some embodiments, touch controller  206 , touch processor  202  and peripherals  204  can be integrated into a single application specific integrated circuit (ASIC). Touch controller  206  can also include an error compensator  250 , which is described in more detail below. 
     Computing system  200  can also include a host processor  228  for receiving outputs from touch processor  202  and performing actions based on the outputs. For example, host processor  228  can be connected to program storage  232  and a display controller, such as an LCD driver  234 . Host processor  228  can use LCD driver  234  to generate an image on touch screen  220 , such as an image of a user interface (UI), and can use touch processor  202  and touch controller  206  to detect a touch on or near touch screen  220 , such a touch input to the displayed UI. The touch input can be used by computer programs stored in program storage  232  to perform actions that can include, but are not limited to, moving an object such as a cursor or pointer, scrolling or panning, adjusting control settings, opening a file or document, viewing a menu, making a selection, executing instructions, operating a peripheral device connected to the host device, answering a telephone call, placing a telephone call, terminating a telephone call, changing the volume or audio settings, storing information related to telephone communications such as addresses, frequently dialed numbers, received calls, missed calls, logging onto a computer or a computer network, permitting authorized individuals access to restricted areas of the computer or computer network, loading a user profile associated with a user&#39;s preferred arrangement of the computer desktop, permitting access to web content, launching a particular program, encrypting or decoding a message, and/or the like. Host processor  228  can also perform additional functions that may not be related to touch processing. 
     Touch screen  220  can include touch sensing circuitry that can include a capacitive sensing medium having a plurality of drive lines  222  and a plurality of sense lines  223 . It should be noted that the term “lines” is a sometimes used herein to mean simply conductive pathways, as one skilled in the art will readily understand, and is not limited to elements that are strictly linear, but includes pathways that change direction, and includes pathways of different size, shape, materials, etc. Drive lines  222  can be driven by stimulation signals  216  from driver logic  214  through a drive interface  224 , and resulting sense signals  217  generated in sense lines  223  can be transmitted through a sense interface  225  to sense channels  208  (also referred to as an event detection and demodulation circuit) in touch controller  206 . In this way, drive lines and sense lines can be part of the touch sensing circuitry that can interact to form capacitive sensing nodes, which can be thought of as touch picture elements (touch pixels), such as touch pixels  226  and  227 . This way of understanding can be particularly useful when touch screen  220  is viewed as capturing an “image” of touch. In other words, after touch controller  206  has determined whether a touch has been detected at each touch pixel in the touch screen, the pattern of touch pixels in the touch screen at which a touch occurred can be thought of as an “image” of touch (e.g. a pattern of fingers touching the touch screen). 
     In some example embodiments, touch screen  220  can be an integrated touch screen in which touch sensing circuit elements of the touch sensing system can be integrated into the display pixels stackups of a display. An example integrated touch screen in which embodiments of the disclosure can be implemented with now be described with reference to  FIGS. 3-6 .  FIG. 3  is a more detailed view of touch screen  220  showing an example configuration of drive lines  222  and sense lines  223  according to embodiments of the disclosure. As shown in  FIG. 3 , each drive line  222  can be formed of one or more drive line segments  301  that can be electrically connected by drive line links  303  at connections  305 . Drive line links  303  are not electrically connected to sense lines  223 , rather, the drive line links can bypass the sense lines through bypasses  307 . Drive lines  222  and sense lines  223  can interact capacitively to form touch pixels such as touch pixels  226  and  227 . Drive lines  222  (i.e., drive line segments  301  and corresponding drive line links  303 ) and sense lines  223  can be formed of electrical circuit elements in touch screen  220 . In the example configuration of  FIG. 3 , each of touch pixels  226  and  227  can include a portion of one drive line segment  301 , a portion of a sense line  223 , and a portion of another drive line segment  301 . For example, touch pixel  226  can include a right-half portion  309  of a drive line segment on one side of a portion  311  of a sense line, and a left-half portion  313  of a drive line segment on the opposite side of portion  311  of the sense line. 
     The circuit elements can include, for example, elements that can exist in conventional LCD displays, as described above. It is noted that circuit elements are not limited to whole circuit components, such a whole capacitor, a whole transistor, etc., but can include portions of circuitry, such as only one of the two plates of a parallel plate capacitor.  FIG. 4  illustrates an example configuration in which common electrodes (Vcom) can form portions of the touch sensing circuitry of a touch sensing system. Each display pixel includes a common electrode  401 , which is a circuit element of the display system circuitry in the pixel stackup (i.e., the stacked material layers forming the display pixels) of the display pixels of some types of conventional LCD displays, e.g., fringe field switching (FFS) displays, that can operate as part of the display system to display an image. 
     In the example shown in  FIG. 4 , each common electrode (Vcom)  401  can serve as a multi-function circuit element that can operate as display circuitry of the display system of touch screen  220  and can also operate as touch sensing circuitry of the touch sensing system. In this example, each common electrode  401  can operate as a common electrode of the display circuitry of the touch screen, and can also operate together when grouped with other common electrodes as touch sensing circuitry of the touch screen. For example, a group of common electrodes  401  can operate together as a capacitive part of a drive line or a sense line of the touch sensing circuitry during the touch sensing phase. Other circuit elements of touch screen  220  can form part of the touch sensing circuitry by, for example, electrically connecting together common electrodes  401  of a region, switching electrical connections, etc. In general, each of the touch sensing circuit elements may be either a multi-function circuit element that can form part of the touch sensing circuitry and can perform one or more other functions, such as forming part of the display circuitry, or may be a single-function circuit element that can operate as touch sensing circuitry only. Similarly, each of the display circuit elements may be either a multi-function circuit element that can operate as display circuitry and perform one or more other functions, such as operating as touch sensing circuitry, or may be a single-function circuit element that can operate as display circuitry only. Therefore, in some embodiments, some of the circuit elements in the display pixel stackups can be multi-function circuit elements and other circuit elements may be single-function circuit elements. In other embodiments, all of the circuit elements of the display pixel stackups may be single-function circuit elements. 
     In addition, although example embodiments herein may describe the display circuitry as operating during a display phase, and describe the touch sensing circuitry as operating during a touch sensing phase, it should be understood that a display phase and a touch sensing phase may be operated at the same time, e.g., partially or completely overlap, or the display phase and touch phase may operate at different times. Also, although example embodiments herein describe certain circuit elements as being multi-function and other circuit elements as being single-function, it should be understood that the circuit elements are not limited to the particular functionality in other embodiments. In other words, a circuit element that is described in one example embodiment herein as a single-function circuit element may be configured as a multi-function circuit element in other embodiments, and vice versa. 
     For example,  FIG. 4  shows common electrodes  401  grouped together to form drive region segments  403  and sense regions  405  that generally correspond to drive line segments  301  and sense lines  223 , respectively. Grouping multi-function circuit elements of display pixels into a region can mean operating the multi-function circuit elements of the display pixels together to perform a common function of the region. Grouping into functional regions may be accomplished through one or a combination of approaches, for example, the structural configuration of the system (e.g., physical breaks and bypasses, voltage line configurations), the operational configuration of the system (e.g., switching circuit elements on/off, changing voltage levels and/or signals on voltage lines), etc. 
     Multi-function circuit elements of display pixels of the touch screen can operate in both the display phase and the touch phase. For example, during a touch phase, common electrodes  401  can be grouped together to form touch signal lines, such as drive regions and sense regions. In some embodiments circuit elements can be grouped to form a continuous touch signal line of one type and a segmented touch signal line of another type. For example,  FIG. 4  shows one example embodiment in which drive region segments  403  and sense regions  405  correspond to drive line segments  301  and sense lines  223  of touch screen  220 . Other configurations are possible in other embodiments, for example, common electrodes  401  could be grouped together such that drive lines are each formed of a continuous drive region and sense lines are each formed of a plurality of sense region segments linked together through connections that bypass a drive region. 
     The drive regions in the example of  FIG. 3  are shown in  FIG. 4  as rectangular regions including a plurality of common electrodes of display pixels, and the sense regions of  FIG. 3  are shown in  FIG. 4  as rectangular regions including a plurality of common electrodes of display pixels extending the vertical length of the LCD. In some embodiments, a touch pixel of the configuration of  FIG. 4  can include, for example, a 64×64 area of display pixels. However, the drive and sense regions are not limited to the shapes, orientations, and positions shown, but can include any suitable configurations according to embodiments of the disclosure. It is to be understood that the display pixels used to form the touch pixels are not limited to those described above, but can be any suitable size or shape to permit touch capabilities according to embodiments of the disclosure. 
       FIG. 5  is a three-dimensional illustration of an exploded view (expanded in the z-direction) of example display pixel stackups  500  showing some of the elements within the pixel stackups of an example integrated touch screen  550 . Stackups  500  can include a configuration of conductive lines that can be used to group common electrodes, such as common electrodes  401 , into drive region segments and sense regions, such as shown in  FIG. 4 , and to link drive region segments to form drive lines. 
     Stackups  500  can include elements in a first metal (M1) layer  501 , a second metal (M2) layer  503 , a common electrode (Vcom) layer  505 , and a third metal (M3) layer  507 . Each display pixel can include a common electrode  509 , such as common electrodes  401  in  FIG. 4 , that is formed in Vcom layer  505 . M3 layer  507  can include connection element  511  that can electrically connect together common electrodes  509 . In some display pixels, breaks  513  can be included in connection element  511  to separate different groups of common electrodes  509  to form drive region segments  515  and a sense region  517 , such as drive region segments  403  and sense region  405 , respectively. Breaks  513  can include breaks in the x-direction that can separate drive region segments  515  from sense region  517 , and breaks in the y-direction that can separate one drive region segment  515  from another drive region segment. M1 layer  501  can include tunnel lines  519  that can electrically connect together drive region segments  515  through connections, such as conductive vias  521 , which can electrically connect tunnel line  519  to the grouped common electrodes in drive region segment display pixels. Tunnel line  519  can run through the display pixels in sense region  517  with no connections to the grouped common electrodes in the sense region, e.g., no vias  521  in the sense region. The M1 layer can also include gate lines  520 . M2 layer  503  can include data lines  523 . Only one gate line  520  and one data line  523  are shown for the sake of clarity; however, a touch screen can include a gate line running through each horizontal row of display pixels and multiple data lines running through each vertical row of display pixels, for example, one data line for each red, green, blue (RGB) color sub-pixel in each pixel in a vertical row of an RGB display integrated touch screen. 
     Structures such as connection elements  511 , tunnel lines  519 , and conductive vias  521  can operate as a touch sensing circuitry of a touch sensing system to detect touch during a touch sensing phase of the touch screen. Structures such as data lines  523 , along with other pixel stackup elements such as transistors, pixel electrodes, common voltage lines, data lines, etc. (not shown), can operate as display circuitry of a display system to display an image on the touch screen during a display phase. Structures such as common electrodes  509  can operate as multifunction circuit elements that can operate as part of both the touch sensing system and the display system. 
     For example, in operation during a touch sensing phase, gate lines  520  can be clamped to a fixed voltage while stimulation signals can be transmitted through a row of drive region segments  515  connected by tunnel lines  519  and conductive vias  521  to form electric fields between the stimulated drive region segments and sense region  517  to create touch pixels, such as touch pixel  226  in  FIG. 2 . In this way, the row of connected together drive region segments  515  can operate as a drive line, such as drive line  222 , and sense region  517  can operate as a sense line, such as sense line  223 . When an object such as a finger approaches or touches a touch pixel, the object can affect the electric fields extending between the drive region segments  515  and the sense region  517 , thereby reducing the amount of charge capacitively coupled to the sense region. This reduction in charge can be sensed by a sense channel of a touch sensing controller connected to the touch screen, such as touch controller  206  shown in  FIG. 2 , and stored in a memory along with similar information of other touch pixels to create an “image” of touch. 
     A touch sensing operation according to embodiments of the disclosure will be described with reference to  FIG. 6 .  FIG. 6  shows partial circuit diagrams of some of the touch sensing circuitry within display pixels in a drive region segment  601  and a sense region  603  of an example touch screen according to embodiments of the disclosure. For the sake of clarity, only one drive region segment is shown. Also for the sake of clarity,  FIG. 6  includes circuit elements illustrated with dashed lines to signify some circuit elements operate primarily as part of the display circuitry and not the touch sensing circuitry. In addition, a touch sensing operation is described primarily in terms of a single display pixel  601   a  of drive region segment  601  and a single display pixel  603   a  of sense region  603 . However, it is understood that other display pixels in drive region segment  601  can include the same touch sensing circuitry as described below for display pixel  601   a , and the other display pixels in sense region  603  can include the same touch sensing circuitry as described below for display pixel  603   a . Thus, the description of the operation of display pixel  601   a  and display pixel  603   a  can be considered as a description of the operation of drive region segment  601  and sense region  603 , respectively. 
     Referring to  FIG. 6 , drive region segment  601  includes a plurality of display pixels including display pixel  601   a . Display pixel  601   a  can include a TFT  607 , a gate line  611 , a data line  613 , a pixel electrode  615 , and a common electrode  617 .  FIG. 6  shows common electrode  617  connected to the common electrodes in other display pixels in drive region segment  601  through a connection element  619  within the display pixels of drive region segment  601  that is used for touch sensing as described in more detail below. Sense region  603  includes a plurality of display pixels including display pixel  603   a . Display pixel  603   a  includes a TFT  609 , a data line  614 , a pixel electrode  616 , and a common electrode  618 . TFT  609  can be connected to the same gate line  611  as TFT  607 .  FIG. 6  shows common electrode  618  connected to the common electrodes in other display pixels in sense region  603  through a connection element  620  that can be connected, for example, in a border region of the touch screen to form an element within the display pixels of sense region  603  that is used for touch sensing as described in more detail below. 
     During a touch sensing phase, drive signals can be applied to common electrodes  617  through a tunnel line  621  that is electrically connected to a portion of connection element  619  within a display pixel  601   b  of drive region segment  601 . The drive signals, which are transmitted to all common electrodes  617  of the display pixels in drive region segment  601  through connection element  619 , can generate an electrical field  623  between the common electrodes of the drive region segment and common electrodes  618  of sense region  603 , which can be connected to a sense amplifier, such as a charge amplifier  626 . Electrical charge can be injected into the structure of connected common electrodes of sense region  603 , and charge amplifier  626  converts the injected charge into a voltage that can be measured. The amount of charge injected, and consequently the measured voltage, can depend on the proximity of a touch object, such as a finger  627 , to the drive and sense regions. In this way, the measured voltage can provide an indication of touch on or near the touch screen. 
     Referring again to  FIG. 5 , it can be seen from  FIG. 5  that some display pixels of touch screen  550  include different elements than other display pixels. For example, a display pixel  551  can include a portion of connection element  511  that has breaks  513  in the x-direction and the y-direction, and display pixel  551  does not include tunnel line  519 . A display pixel  553  can include a portion of connection element  511  that has a break  513  in the x-direction, but not in the y-direction, and can include a portion of tunnel line  519  and a via  521 . Other display pixels can include other differences in the configuration of stackup elements including, for example, no breaks  513  in connection element  511 , a portion of tunnel line  519  without a via  521 , etc. Differences in the configurations of the elements in display pixel stackups can result in different error mechanisms, as described in some examples below in more detail. 
       FIG. 7  illustrates one example structure of a display pixel according to one embodiment of the disclosure.  FIG. 7  shows a touch screen  700  that can include a drive Vcom  701 , a sense Vcom  703 , and a pixel electrode  705 . The pixel electrode  705  can be connected to a display pixel TFT  707  through a drain  709 . Display pixel TFT  707  can include a gate line  711 , which can be a common gate line to the sense Vcom  703  (although not shown in the figure). During a touch sensing phase, gate line  711  can be clamped to a fixed voltage VGL. Drive Vcom can be driven by a drive signal, which can generate field lines  713 . Some of field lines  713  can exit a cover glass  715  and reach finger  717 . The field lines  713  that are affected by finger  717  can allow sense Vcom  703  to measure touch information. As shown in the figure, some of field lines  713  that reach sense Vcom  703  do not penetrate cover glass  715 . These field lines may detect little if any touch information about finger  717 . 
     Some of field lines  713  emitted from drive Vcom  701  can reach pixel electrode  705 . Consequently, part of the drive signal that can be driving drive Vcom  701  can be picked up pixel electrode  705 , and this signal can be passed to gate line  711  through drain  709 . In particular, even though gate line  711  may be clamped to a fixed voltage, there can be a capacitance between drain  709  and gate line  711  that can allow a capacitive coupling of the portion of the drive signal captured by pixel electrode  705  into gate line  711 . The field lines  713  that are captured by pixel electrode  705  can travel through a liquid crystal  719  of the touch screen  700 . Similarly, a portion of the field lines  713  between drive Vcom  701  and sense Vcom  703  can also travel through a portion of liquid crystal  719 . 
     In some displays, for example, in-plane switching (IPS), the dielectric constant of the liquid crystal  719  can vary depending on the pixel electrode-to-drive Vcom voltage applied to the display pixel. In some embodiments, the dielectric constant of liquid crystal  719  can change dramatically (e.g., ranging from 3 to 10) in a direction parallel to cover glass  715  along the y-direction as indicated by the arrow in  FIG. 7 . The pixel electrode-to-drive Vcom voltage can be applied at different voltage values by the display system in order to set the luminance of each display pixel in proportion to the voltage value. In other words, the dielectric constants of the liquid crystal in the display pixels through which the field lines  713  travel can vary, particularly at the location where the field lines are approximately collinear with the y-direction as shown in the figure. 
     Although  FIG. 7  illustrates a single drive Vcom  701  and a single sense Vcom  703 , these Vcoms can in fact be connected together Vcoms of a particular drive region and sense region such as the regions shown in  FIGS. 4 and 5 . Therefore, although not shown in the figures, the field lines may pass through many display pixel with different luminances associated with each. 
       FIGS. 8 and 9  illustrate two different error mechanisms  800  and  900  of the example portion of touch screen  700  in  FIG. 7 .  FIG. 8  illustrates an example circuit diagram of a model of a first error mechanism. A drive amplifier  801  can drive the drive region Vcom  701  with a drive signal as described above. A portion of the drive signal can be captured by pixel electrode  705  through field lines passing through liquid crystal  719 . Liquid crystal  719  of display pixels in the drive region can have a capacitance, CLC drive  803 . Once captured by pixel electrode  705 , the signal can be passed to gate line  711  through a capacitance between drain  709  and gate line  711 , CGD drive  805 . Gate line  711  can be shared with the display pixels of the sense region, therefore the signal may be leaked into the display pixels of the sense region through a similar mechanism shown in the figure. In particular, the signal can pass into sense pixel electrode  807  through a gate-to-drain capacitance CGD sense  809  of the TFTs in the display pixels of the sense region. The signal can then be passed from pixel electrode  807  to sense region Vcom  703  through the liquid crystal  719  of the sense region display pixels, the liquid crystal having an associated capacitance CLC sense  811 . The leaked signal can show up in the touch measurements detected by sense amplifier  813 . 
     During the touch phase, in order to help reduce the above-described leakage, gate line  711  can be clamped to a VGL voltage  817  through a gate line TFT  815 . Ideally, if gate line  711  could be perfectly clamped to a fixed voltage such as VGL  817 , then no leakage could occur between drive region Vcom  701  and sense region Vcom  703 . However, various resistances associated with gate line  711  can prevent the gate line from being perfectly clamped, that is, can allow leakage of the drive signal from the drive region to the sense region. For example, gate line  711  can have a gate line resistance  819  that may be spread throughout the gate line, although in  FIG. 8 , it is shown in one location. Gate line TFT  815  can have an associated TFT resistance  821 . Also, a routing resistance  823  can be associated with the conductive lines used to route the gate line TFT  815  to VGL  817 . 
     In the example error mechanism shown in  FIG. 8 , error in the sense signal can be introduced through various sources. One error source that can be introduced into the touch sensing signal through the error mechanism shown in  FIG. 8  is the drive signal generated by drive amplifier  801 . Another error source can be CLC drive  803  and CLC sense  811 , which can change depending on the pixel luminances of the display pixels through which the field lines  713  pass between drive Vcom  701  and pixel electrode  705 , and the field lines which travel from sense Vcom  703  to a corresponding pixel electrode in the sense region, respectively, as described above. In other words, the amount of the drive signal that can be leaked in this error mechanism can be dependent on the average pixel luminance associated with the drive region and sense region display pixels. Because the display pixel luminances depend on the image being displayed, the error introduced through this error mechanism can be said to be image-dependent. 
     Another error source that can introduce an error using this error mechanism can be associated with the gate-to-drain capacitances, CGD drive  805  and CGD sense  809 , of the drive and sense region TFTs. In particular, the gate-to-drain capacitances can be affected by factors such as temperature, ambient light, etc. For example, a local temperature variance may cause the gate-to-drain capacitances of the local pixels to be different than other areas of the touch screen, and consequently the amount of drive signal in those local areas may be different than in the rest of the touch screen. In another example, gate-to-drain capacitance can depend on the currently displayed image, because the displayed image can change the voltage on the pixel electrode, so that the gate-to-drain voltage (VGD) can vary depending on image. In some embodiments that utilize, for example, diodes and/or transistors, CGD can depend strongly on the VGD. For example, the CGD can be high for low values of VGD, and the CGD can be low for high values of VGD. 
     The error mechanism shown in  FIG. 8  can allow a portion of a drive signal from drive amplifier  801  to be leaked into the sense amplifier  813  in dependence on a number of variable error sources, such as the average luminance of associated display pixels in the drive and sense regions, and average local temperature of the display pixel TFTs, which can cause the gate-to-drain capacitances of display pixels in the drive and sense regions to vary, etc. Other elements of the circuit diagram can play a role in contributing to the error, such as the various resistances associated with gate line  711 , as described above. These sources, or causes, of the error may be fixed, i.e., not variable, over time, location within the touch screen, etc. In other cases, the values of, for example, the various gate line resistances could be variable, for example, depending on location within the touch screen due to manufacturing inconsistencies. In the same way, other elements or structures within the touch screen may vary non-uniformly due to manufacturing errors. These differences among display pixels in different locations of the touch screen can contribute different amounts to the error mechanisms associated with the corresponding pixels. Thus, various error sources that can introduce error through a given error mechanism can be, for example, static error sources, dynamic error sources in time, position on the touch screen, an amount of the area of the touch screen, strength of the given error source, etc. The error sources might be, for example, known error sources or unknown error sources. Likewise, the specific error mechanism may be known or unknown. 
     Referring to  FIGS. 7 and 9 , another example error mechanism according to embodiments of the disclosure will now be described. As mentioned above with regard to  FIG. 7 , field lines  713  from drive Vcom  701  that are received by sense Vcom  703  travel through liquid crystal  719 . Because the dielectric constant of liquid crystal  719  can change in the drive region display pixels and the sense region display pixels, based on the luminance of the pixels, the capacitance between drive Vcom  701  and sense Vcom  703  can change depending on the average luminance of the display pixels.  FIG. 9  illustrates an example error mechanism related to the change in the liquid crystal capacitance between the drive and sense regions.  FIG. 9  illustrates drive region Vcom  701  driven by drive amplifier  801  and sense region Vcom  703  which can output a sense signal to sense amplifier  803  for measurement of touch. Also illustrated in the figure are a liquid crystal capacitance of the drive and sense regions, C′LC drive  901  and C′LC sense  903 , respectively. The example error mechanism shown in  FIG. 5  can be the same mechanism by which touch is sensed. In other words, the path taken by the drive signals to reach the sense amplifier can be the path of the field lines that are used to sense touch. 
     In this example, the source of the error that can introduce an error into the sense signal can be the variable dielectric constant associated with the liquid crystal, which in turn can produce a varying capacitance in the touch-sensing mechanism or signal pathway. In this example, the capacitances associated with the drive region and the sense region can be different than the capacitances in the example error mechanism shown in  FIG. 8  because the path taken by the field lines in each example error mechanism can be different. For example, referring to  FIG. 7 , the field lines through the liquid crystal in the  FIG. 8  error mechanism are seen on the left side of the drive Vcom extending to the pixel electrode and correspondingly on the sense region side, not shown in the figure, field lines extending from sense Vcom  703  to corresponding pixel electrode. Turning to the example of  FIG. 9 , however, the relevant field lines through the liquid crystal  719  are shown extending from the right side of drive Vcom  701  to the left side of sense Vcom  703 . Therefore, in  FIG. 9 , the values CLC drive and CLC sense are given prime superscripts. 
     In the example error mechanism of  FIG. 9 , it is noted that the only source of error is the pixel luminance. In addition, it is noted that the relevant pixels can be different than the relevant pixels in the example of  FIG. 8 , because of the different paths taken by the relevant field lines  713 . Of course, there may be other elements in the error mechanism/touch-sensing mechanism shown in  FIG. 9 , such as, for example, the cover glass, other elements of the display, etc. It is also noted that some field lines can travel through all of the relevant structures of the touch screen, for example, the field lines extending beyond the cover glass  715 . On the other hand, some field lines  713  extend through only some of the structures. For example, some field lines do not reach the cover glass and may only travel through liquid crystal  719 . In that regard, it is further noted that some field lines may travel through more liquid crystal than other field lines, some field lines may have larger portions that are parallel or collinear with axis Y (in which case, those field lines may be more affected by the changing dielectric constant than field lines that have less of a portion collinear with axis Y). 
       FIG. 10  illustrates an example circuit diagram of the example touch screen configuration  700  shown in  FIG. 7 .  FIG. 10  includes the example error mechanisms  800  and  900  of  FIGS. 8 and 9 . In the previous examples of  FIGS. 7 through 9 , for the sake of clarity, only one drive Vcom/sense Vcom pair were described. However, as shown in the example embodiments described in  FIGS. 4 through 6 , the drive lines and sense lines of an integrated touch screen can include the Vcoms of multiple display pixels grouped together in a region of the touch screen. In the example circuit diagram of  FIG. 10 , a drive line  1001  can include drive region segments such as drive region segment  403  linked together with bypasses as described in  FIGS. 3 and 5 , and a sense line  1003  can include a sense region such as sense region  405  including a sense region such as sense region  405 , including electrically connected together Vcoms of display pixels in the sense region as described in the figures. Gate lines  1005  can include multiple gate lines such as gate lines  711  running through multiple rows of display pixels in the drive line  1001  and portion of the sense line  1003 . For example, there may be 60 gate lines  1005  in each drive line  1001 . An effective gate line resistance  1007  can include a combination of resistances associated with the multiple gate lines  1005 , such as gate line resistance  819 , TFT resistance  821 , and routing resistance  823  of each of the 60 gate lines, for example. Likewise, a gate-drive capacitance  1009  can include a combination of various capacitances between the multiple drive Vcom  701  and each corresponding gate line  1005 . For example, gate-drive capacitance  1009  can include a combination of the CLC drive  803  and CGD drive  805  of each display pixel in the drive region. Likewise, a gate-sense capacitance  1011  can include a combination of the CLC sense  811  and CGD sense  809  of all of the display pixels in the sense region. Effective drive-sense capacitance  1013  can, therefore, represent the total effective capacitance between the drive and sense regions due to the various capacitances associated with each of the display pixels in the regions. 
     An effective drive-sense capacitance  1015  can include a combination of C′LC drive  901  and C′LC sense  903  of all of the display pixels in the corresponding drive regions and sense regions. Drive amplifier  801  can generate a drive signal  1017  on drive line  1001  that can emanate from the multiple drive Vcoms in the drive region through the various error mechanisms of error mechanism  800 , represented by effective drive-sense capacitance  1013 , and error mechanism  900 , represented by effective drive-sense capacitance  1015 , as well as through touch-sensing mechanism to generate a signal capacitance, CSIG, which can represent touch information which is received by sense line  1003  and amplified by sense amplifier  813 , which can include a feedback capacitance  1021  to result in a sense signal  1023 . Therefore, sense signal  1023  can be a superposition of multiple CSIG signals  1019 , carrying touch information, together with multiple signals due to error mechanisms  800  and  900 . 
     Referring now to  FIGS. 10 and 11 , and example method of compensating for error in touch measurements, will now be described according to an example embodiment of the disclosure. In the example error mechanisms of  FIG. 10 , namely, error mechanism  800  and error mechanism  900 , certain error sources were the cause of error introduced by way of the error mechanisms. If one or more error sources are known, the error associated with the error source can be measured together with a value of the error source, for example, in a factory setting during a calibration phase. In other words, if it is known that a certain measurable or known characteristic of the touch screen will cause an error, then that characteristic can be measured under controlled circumstances, for example, using test equipment, and at the same time an error produced in the touch-sense signal can be measured. By measuring a range of error source values, together with corresponding error result values, an understanding of the relationship between the error source and the error produced can be developed. For example, in one example, the measurements taken during the calibration phase at the factory can be stored in a computer-readable medium in the device, for example, in a lookup table (LUT), and the device can access the values to make compensation adjustments for touch-sense measurements if a corresponding value of the source error is known at the time of the touch measurement. In some embodiments, the relationship between source error and the resulting error can be summarized as a mathematical function and stored in a computer-readable medium for the device to use during compensation. Once the relationship between the source of the error and the error produced is stored on a device, such as a touch screen, the method according to  FIG. 11  may be used during the operation of the device by a user. 
     Referring to  FIG. 11 , during a touch phase of the device, touch-sensing measurements can be obtained ( 1101 ), and values of the known error source at the time of the touch-sensing measurement can be obtained ( 1102 ). Referring again to the previous examples in  FIGS. 7 through 10 , various error sources could include average display pixel luminance, localized temperature, etc. Error sources that are unknown at the time of calibration may not be able to be adjusted for, for example, because no test or calibration can be performed by varying an unknown value to obtain the relationship between the unknown value and the error produced. However, the method according to  FIG. 11  may have the advantage that the particular error mechanism through which the error source introduces error into the touch measurement need not be known. In other words, for example, if it is known that average luminance of display pixels of a touch pixel can have an effect on the measurements of touch, empirical testing can be performed to determine the relationship, and further to store the relationship for later use during compensation of the touch measurements. Of course, one skilled in the art would readily understand after reading the disclosure that other methods such as interpolation of data in a LUT and other methods of storing and using relationship data can be used in various embodiments. 
     Turning again to  FIG. 11 , error compensation values can be obtained ( 1103 ) from the LUT of predetermined values based on the known value of the error source at the time of touch measurement. The touch-sensing measurements and the corresponding error compensation values can be sent to an error compensator, such as error compensator  250  in  FIG. 2 , where the obtained error compensation value can be used to compensate the touch measurement, the obtained compensation value being reflective of the relationship between the error source and the produced error at that value. 
     Another example method of error compensation according to various embodiments of the disclosure will now be described with reference to  FIGS. 12 through 18 . 
       FIG. 12  illustrates a touch screen  1200  according to various embodiments of the disclosure. A portion of touch screen  1200  illustrated in  FIG. 12  shows multiple display pixels and that can each include a common electrode  1201 . Other structures of the display pixels are not shown, for the sake of clarity. Various groupings of common electrodes  1201  can be formed by, for example, connection elements such as the connection elements shown in  FIG. 5 . The groupings can include drive region segments  1203 , sense regions  1205  and compensation regions  1207 . As shown in the example embodiment of  FIG. 12 , compensation regions  1207  are positioned between adjacent drive region segments  1203  and sense regions  1205 . 
       FIG. 13  illustrates an example operation of touch-sensing during a touch-sensing phase of touch screen  1200 . Similar to the structure shown in the example of  FIG. 7 , touch screen  1200  includes a drive Vcom  1301 , a sense Vcom  1303 , and a pixel electrode  1305 . The pixel electrode  1305  is connected to a display pixel TFT  1307  through a drain  1309 . Display pixel TFT  1307  includes a gate line  1311 , which is a common gate line to the sense Vcom  1303  (although not shown in the figure). When driven by a drive signal, drive Vcom  1301  emits field lines  1313 . Some of the field lines  1313  exit a cover glass  1315  and reach a finger  1317 . The field lines  1313  that are affected by finger  1317  allow sense Vcom  1303  to measure touch information. 
     Some of field lines  1313  emitted from drive Vcom  1301  can reach pixel electrode  1305 . In this way, similar to the example embodiment in  FIG. 7 , part of the drive signal that is driving Vcom  1301  can be picked up by pixel electrode  1305 , and this signal can be passed to gate line  1311  through drain  1309 . In particular, even though gate line  1311  may be clamped to a fixed voltage, there can be a capacitance between drain  1309  and gate line  1311  that allows a capacitive coupling of the portion of the drive signal captured by pixel electrode  1305  into gate line  1311 . The field lines  1313  that are captured by pixel electrode  1305  can travel through a liquid crystal  1319  of touch screen  1200 . Similarly, a portion of field lines  1313  between drive Vcom  1301  and sense Vcom  1303  can also travel through a portion of liquid crystal  1319 . 
     Unlike the example embodiment shown in  FIG. 7 , touch screen  1200  includes a compensation Vcom  1321 . As shown in  FIG. 12 , compensation Vcom  1321  can be in a compensation region  1207  positioned between a drive region segment  1203  and a sense region  1205 . Some of the field lines  1313  from drive Vcom  1301  are captured by compensation Vcom  1321 . In this example embodiment, compensation Vcom  1321  was designed to capture field lines  1313  that have not penetrated to the outside of cover glass  1315 . In this way, for example, the amount of touch detected by compensation Vcom  1321  can be reduced or minimized, and in some embodiments may be negligible. In contrast, most of the field lines  1313  from drive Vcom  1301  to sense Vcom  1303  can extend to the outside of cover glass  1315 , therefore, the amount of touch detected by sense Vcom  1303  can remain similar to the amount of touch detected in the example embodiment shown in  FIG. 7 . 
     In sum, compensation Vcom  1321  can be selected to detect little to no amount of touch information, while at the same time compensation Vcom can be positioned in such a way that it can be coupled to the same error mechanisms that introduce errors into the sense measurements of sense Vcom  1303 .  FIGS. 14 and 15  illustrate more details of example error mechanisms that can occur in the example embodiment of  FIG. 13 . 
       FIG. 14  illustrates a model of example error mechanisms  1400  and  1450  of touch screen  1200  according to embodiments of the disclosure. As described in more detail below, error mechanism  1400  can include the electrically coupled path between drive Vcom  1301  and sense Vcom  1303 . Similar to error mechanism  800  of  FIG. 8 , a drive amplifier  1401  drives drive region Vcom  1301  with a drive signal as described above. A portion of the drive signal can be captured by pixel electrode  1305  with field lines passing through liquid crystal  1319 . Liquid crystal  1319  has a capacitance, CLC drive  1403 , and once captured by pixel electrode  1305 , the signal can be passed to gate line  1311  through a capacitance between drain  1309  and gate line  1311 , CGD drive  1405 . Gate line  1311  is shared with the display pixels of the sense region, therefore the signal may be leaked into the display pixels of the sense region through a similar mechanism shown in the figure. In particular, the signal can pass into sense pixel electrode  1407  through a gate-to-drain capacitance CGD sense  1409  of the TFTs in the display pixels of the sense region. The signal can then be passed from pixel electrode  1407  to sense region Vcom  1303  through the liquid crystal  1319  of the sense region display pixels, the liquid crystal having an associated capacitance CLC sense  1411 . The leaked signal can show up in the touch measurements detected by sense amplifier  1413 . 
     During the touch phase when the above-described leakage can occur, gate line  1311  can be clamped to a VGL voltage  1417  through a gate line TFT  1415 . As described above with regard to  FIG. 8 , if gate line  1311  could be perfectly clamped to a fixed voltage such as VGL  1417 , then no leakage could occur between drive region Vcom  1301  and sense region Vcom  1303 . However, various resistances associated with gate line  1311  can prevent the gate line from being perfectly clamped, that is, can allow leakage of the drive signal from the drive region to the sense region. For example, gate line  1311  can have a gate line resistance  1419  that may be spread throughout the gate line, although in  FIG. 14 , it is shown in one location. Gate line TFT  1415  can have an associated TFT resistance  1421 . Also, a routing resistance  1423  can be associated with the conductive lines used to route the gate line TFT  1415  to VGL  1417 . 
     Similar to the example embodiment of  FIG. 8 , in the example error mechanism shown in  FIG. 14 , error in the sense signal can be introduced through various sources, such as through variance of pixel luminance, temperature of the touch screen, etc. 
     Error mechanism  1450  can include the electrically coupled path between drive Vcom  1301  and compensation Vcom  1321 . Error mechanism  1450  can include the same and/or similar elements as error mechanism  1400 . For example, error mechanism  1450  can include drive Vcom  1301 , CLCdrive  1403 , drive pixel electrode  1305 , and CGDdrive  1405 , which are some of the same elements of error mechanism  1400 . Error mechanism  1450  can also include a gate-to-drain capacitance, CGDcomp  1425 , a compensation region pixel electrode  1427 , a liquid crystal capacitance, CLCcomp  1429 , and compensation Vcom  1321 . Because of the configuration of the compensation  1207 , CGDcomp  1425  can be similarly affected by error sources, such as local temperature, as CGDsense  1409 , and CLCcomp  1429  can be similarly affected by error sources, such as pixel luminance, as CLCsense  1411 . Therefore, error mechanism  1450  can provide a mechanism that reflects error mechanism  1400 . During the touch phase, a compensation signal can be measured from compensation Vcom  1321  with a compensation amplifier  1431 , for example. 
     Because error mechanisms  1400  and  1450  are similar, the compensation signal can include a similar error as the error introduced in the touch sensing signal. However, because the compensation region receives few, if any, field lines that extend outside of the cover glass, the compensation signal can include little, if any, touch information. Therefore, the compensation signal can provide a more direct indication of the error introduced into the touch sensing signal. Due to various factors, the amount of error measured by the compensation may not be the same as the amount of error introduced into the touch sensing signal, but the two amounts of error may be related by some relationship that can be determined. In some example embodiments, the relationship can be determined empirically. I some embodiments, the relationship can be determined by analyzing the circuits of each of the respective error mechanisms. Once the relationship between measured compensation error and measured touch sensing error is determined, the relationship can be stored in, for example, a computer-readable medium to be retrieved for an error compensation process, described in more detail below. 
     One potential advantage configuring a compensation sensor to be coupled to the same or similar error mechanism as the touch sensing region, for example, is that it can be possible to compensate for unknown error sources that introduce error into the touch sensing measurement by way of the error mechanism. In particular, because the compensation sensor can provide a real-time model of the drive-to-sense error mechanism, any error source that enters through the drive-to-sense error mechanism can also enter the drive-to-compensation error mechanism and be detected by the compensation sensor. In some embodiments, for example, unknown non-uniformities of the touch screen manufacture that cause error may be compensated without specific calibration directed to the error source, which may be impossible if the error source is unknown or, even if the error source is known, difficult to perform. 
     Referring to  FIG. 15 , other example error mechanisms according to embodiments of the disclosure will now be described. Similar to the example error mechanism  900 , an example error mechanism  1500  of touch screen  1200  can result from field lines  1313  from drive Vcom  1301  that are received by sense Vcom  1303  extend primarily through liquid crystal  1319  in display pixels of the drive region and the sense region. Therefore, error mechanism  1500  can include drive Vcom  1301 , liquid crystal capacitances of the drive region and sense region, C′LC drive  1501  and C′LC sense  1503 , respectively, and sense Vcom  1303 . As in the previous example, the example error mechanism shown in  FIG. 15  is the same mechanism by which touch is sensed. 
     Error mechanism  1550  can be similar to error mechanism  1500 , and can result from field lines  1313  extending through liquid crystal  1319  primarily in the drive region and compensation region. Therefore, error mechanism  1550  can include drive Vcom  1301 , liquid crystal capacitances of the drive region and compensation region, C′LC drive  1501  and C′LC comp  1505 , respectively, and compensation Vcom  1321 . In some embodiments, some field lines of error mechanism  1500  may extend through liquid crystal of the compensation region, and the associated error mechanism may include an additional associated capacitance. 
     Similar to error mechanism  900 , it is noted that the only source of error that introduces error through error mechanism  1550  may be the pixel luminance. In addition, it is noted that the relevant pixels can be different than the relevant pixels in the example of  FIG. 14 , because of the different paths taken by the relevant field lines  1313 . Of course, there may be other elements in the error mechanism/touch-sensing mechanism shown in  FIG. 15 , such as, for example, the cover glass, other elements of the display, etc. It is also noted that some field lines can travel through all of the relevant structures of the touch screen, for example, the field lines extending beyond the cover glass  1315 . On the other hand, some field lines  1313  extend through only some of the structures. For example, some field lines do not reach the cover glass and may only travel through liquid crystal  1319 . In that regard, it is further noted that some field lines may travel through more liquid crystal than other field lines, some field lines may have larger portions that are parallel and collinear with axis Y (in which case, those field lines may be more affected by the changing dielectric constant than field lines that have less of a portion collinear with axis Y). 
       FIG. 16  illustrates an example configuration for measuring compensation signals according to embodiments of the disclosure. An example touch screen  1600  can include drive regions  1601  and sense regions  1603  with compensation regions  1605  positioned in between the drive and sense regions. Drive amplifier  1401  can provide a drive signal to the drive region and a sense amplifier can measure a sense signal through sense amplifier  1413 . A single compensation amplifier  1607  can be connected to two compensation regions adjacent to the same sense region  1603 , for each sense region of touch screen  1600 . The electrical connections between the compensation regions and the compensation amplifiers can be included in, for example, sense interface  225  and the compensation amplifiers can be included in, for example, touch controller  206  alongside sense channels  208 . In this regard, compensation signals can be processed by touch controller  206  in the same way as sense signals, e.g., including demodulation in some embodiments such as embodiments in which the drive regions are concurrently stimulated with drive signals, e.g., in a multi-stim drive scheme. In this way, for example, an amount of error reflected by the information in one or more compensation signals can be extracted from the one or more compensation signals in a similar way that an amount of touch (and an amount of error) can be extracted from one or more sense signals. Fields lines  1609  extending from the drive regions  1601  can be captured by the sense regions  1603  and the compensation regions  1605 . Some field lines can be disturbed by a finger  1611 , which can result in touch information being included in a sense signal. Other elements of touch screen  1600  are also illustrated, including liquid crystal  1613 . 
     Connecting pairs of compensation regions around each sense region can provide compensation information that can be specific to each individual touch pixel, for example. 
       FIG. 17  illustrates another example configuration for measuring compensation signals according to embodiments of the disclosure. The configuration of  FIG. 17  can be identical to  FIG. 16  with the exception that each compensation amplifier  1701  is connected to more than two compensation regions. For example, each compensation amplifier can be connected to two pairs of compensation regions. In this example, the number of compensation amplifiers can be reduced. 
       FIG. 18  illustrates an example circuit diagram including drive-to-compensation operation through error mechanisms  1450  and  1550 , and including touch sensing, if any. In the previous examples of  FIGS. 13 through 15 , for the sake of clarity, only one drive Vcom/comp Vcom pair was described. In the example circuit diagram of  FIG. 18 , a drive line  1801  can include drive region segments such as drive region segment  403  linked together with bypasses as described in  FIGS. 3 and 5 , and a compensation sensor  1803  can include a compensation region such as compensation region  1207 , including electrically connected together Vcoms of display pixels in the compensation region as described in the figures. As described in  FIGS. 16 and 17 , compensation sensor  1803  can include multiple compensation regions, such as a pair, two pairs, all compensation regions, etc. Gate lines  1805  can include multiple gate lines such as gate lines  1311  running through multiple rows of display pixels in the drive line  1801  and portion of the sense line  1803 . For example, there may be 60 gate lines  1805  in each drive line  1801 . An effective gate line resistance  1807  can include a combination of resistances associated with the multiple gate lines  1805 , such as gate line resistance  1419 , TFT resistance  1421 , and routing resistance  1423  of each of the 60 gate lines, for example. Likewise, a gate-drive capacitance  1809  can include a combination of various capacitances between the multiple drive Vcom  701  and each corresponding gate line  1805 . For example, gate-drive capacitance  1809  can include a combination of the CLC drive  1403  and CGD drive  1405  of each display pixel in the drive region. Likewise, a gate-comp capacitance  1811  can include a combination of the CLC comp  1429  and CGD comp  1425  of all of the display pixels in the compensation region. Effective drive-comp capacitance  1813  can, therefore, represent the total effective capacitance between the drive and compensation regions due to the various capacitances associated with each of the display pixels in the regions. 
     An effective drive-sense capacitance  1815  can include a combination of C′LC drive  901  and C′LC comp  1503  of all of the display pixels in the corresponding drive regions and compensation regions. Drive amplifier  1401  can generate a drive signal  1817  on drive line  1801  that can emanate from the multiple drive Vcoms in the drive region through the various error mechanisms of error mechanism  1450 , represented by effective drive-comp capacitance  1813 , and error mechanism  1550 , represented by effective drive-comp capacitance  1815 , as well as through touch-sensing mechanism to generate a signal capacitance, CSIG  1819 , which represents touch information which is received by compensation sensor  1803  and amplified by compensation amplifier  1321 , which can include a feedback capacitance  1821  to result in a compensation signal  1823 . Therefore, compensation signal  1823  can be a superposition of multiple signals due to error mechanisms  1450  and  1550 , and may also carry some touch information due to a small amount of CSIG signals  1819 , though as a result of the design of compensation sensor  1803 , the amount of touch information measured should be proportionately less than the sense region. 
     The drive-to-sense interaction in example embodiments of touch screens including error mechanisms  1400  and  1500  can be similarly represented by the example circuit diagram shown in  FIG. 10 , although one skilled in the art would readily understand that the actual values of the elements of the circuit would be different due to the differences in the configurations of touch screens  700  and  1200 . In short, the sense signal output by sense amplifier  1413  can include a superposition of a touch sensing signal carrying touch information based on measured Csig signals and error introduced through error mechanisms  1400  and  1500  by various known and/or unknown error sources. 
       FIG. 19  illustrates a flowchart of an example method of compensating for error in touch sense signals with compensation signals measured by compensation sensors such as the example compensation sensors described above. A touch sensing measurement can be obtained ( 1901 ), and a compensation sensor measurement can be obtained ( 1902 ). The touch sensing measurement and the compensation sensor measurement can be sent to an error compensator, such as, for example, error compensator  250  in  FIG. 2 , where the touch sensing measurement can be compensated ( 1903 ) based on the compensation measurement and a predetermined relationship, which can be predetermined empirically, for example, as described above. In some embodiments, the relationship can be defined by the following function: A−K*B, where A can be the amount of the sense signal measurement, B can be the amount of compensation signal measurement, and K can be a scalar. In some embodiments, the value of K can be determined empirically and stored in a computer-readable medium of the touch screen. In some embodiments, the value of K can be determined by analyzing the touch sensing and compensation systems through circuit analysis to determine K mathematically. In some embodiments, K can vary, for example, based on other system operational parameters, such as drive signal frequency. In this case, multiple values of K can be stored and the particular value of K that corresponds to the current operational parameters can be retrieved for error compensation calculations. In one approximation, the value of K can be set to equal the ratio of area of the touch sensing region to the compensation region. 
     In some embodiments, error compensation can be done after a demodulation process to extract information from the sense signals and from the compensation signals. For example, as a result of the demod, one or more sense signals can be processed into extract a sense value that can include an amount of touch measured and an amount of error. Likewise, an amount of error (and in some embodiments, an amount of touch) can be extracted from one or more compensation signals for use in the error compensation process. In embodiments in which the compensation sensor detects some amount of touch, the ratio of the amount of touch to the amount of error detected by the compensation sensor should not exceed the ratio of the amount of touch to the amount of error detected by the corresponding sense region. In this way, error in the sense signal can be reduced or eliminated without eliminating the touch information of the sense signal. 
       FIG. 20  illustrates an example touch screen  2000  according to embodiments of the disclosure showing a more general view of an example configuration of drive regions  2001 , sense regions  2003 , compensation regions  2005 , drive amplifiers  2007 , sense amplifiers  2009 , and compensation amplifiers  2011 . 
       FIG. 21  illustrates a portion of an example touch screen  2100  including an example diamond configuration of regions, including drive regions  2101 , sense regions  2103 , and compensation regions  2105 . 
       FIG. 22  illustrates a flowchart of an example combination method of compensating for error in sense signal measurements that includes measuring compensation signals of compensation sensors, and using predetermined error compensation values stored in a LUT. In this example method, average luminance of display pixels can be a source of error, for example, as in the example embodiments described above. A combination method may be beneficial in some embodiments, for example, if a compensation sensor approach does not work well in certain situations. In the example embodiment of touch screen  1200 , for example, an image may be displayed in which high luminance values (such as the color white) can be displayed by all of the display pixels in the compensation region of a compensation sensor, while low luminance values (such as the color black) can be displayed by all of the display pixels in a corresponding sense region. In this case, error introduced into the sense region through an error mechanism such as error mechanism  1400  of  FIG. 14  can be substantially different than an error introduced into the compensation region through a corresponding error mechanism such as error mechanism  1450 . In particular, if all of the pixels in the compensation have high luminance values, the liquid crystal capacitance portion of the drive-comp error mechanism can be different than the drive-sense error mechanism, in which all of the pixel luminances are low. Therefore, for some “worst-case” images, the compensation signal measurement may incorrectly compensation for error. In some embodiments, utilizing predetermined error compensation values that have been measured for the worst-case images can provide more accurate error compensation. 
     Referring to  FIG. 22 , a touch screen in a touch phase of operation can obtain ( 2200 ) luminance values from a frame buffer of the display system that stores luminance values of display pixels for use in a next display scan during a display phase and can determine ( 2202 ) if the luminance values represent a worst-case image or portion of an image relevant to individual touch pixels, for example. If a worst-case image is determined, a touch sensing measurement can be obtained ( 2203 ) and a predetermined error compensation value can be obtained ( 2204 ) from a LUT of predetermined values. The touch measurements can be compensated ( 2205 ) based on the predetermined error values. 
     If the image is determined not to be a worst-case image at  2202 , touch sensing and compensation sensor measurements can be obtained ( 2206 ). The touch measurement can be compensated ( 2207 ) based on the compensation measurement and a predetermined relationship. A determination ( 2208 ) can be made whether or not a calibration should be performed. If it is determined not to perform calibration, the process can return to  2201 . If a calibration is to be performed, a predetermined error compensation value for the current image can be obtained ( 2209 ) from the LUT of predetermined values, and the predetermined values can be compared ( 2210 ) with the compensation measurement values. If there is a large difference between the two values, the predetermined values can be calibrated ( 2211 ) based on the difference. 
     Although embodiments of this disclosure have been fully described with reference to the accompanying drawings, it is to be noted that various changes and modifications including, but not limited to, combining features of different embodiments, omitting a feature or features, etc., as will be apparent to those skilled in the art in light of the present description and figures. 
     For example, one or more of the functions of computing system  200  described above can be performed by firmware stored in memory (e.g. one of the peripherals  204  in  FIG. 2 ) and executed by touch processor  202 , or stored in program storage  232  and executed by host processor  228 . The firmware can also be stored and/or transported within any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “computer-readable medium” can be any medium that can contain or store the program for use by or in connection with the instruction execution system, apparatus, or device. The computer readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, a portable computer diskette (magnetic), a random access memory (RAM) (magnetic), a read-only memory (ROM) (magnetic), an erasable programmable read-only memory (EPROM) (magnetic), a portable optical disc such a CD, CD-R, CD-RW, DVD, DVD-R, or DVD-RW, or flash memory such as compact flash cards, secured digital cards, USB memory devices, memory sticks, and the like. 
     The firmware can also be propagated within any transport medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “transport medium” can be any medium that can communicate, propagate or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The transport readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic or infrared wired or wireless propagation medium. 
     Example embodiments may be described herein with reference to a Cartesian coordinate system in which the x-direction and the y-direction can be equated to the horizontal direction and the vertical direction, respectively. However, one skilled in the art will understand that reference to a particular coordinate system is simply for the purpose of clarity, and does not limit the direction of the elements to a particular direction or a particular coordinate system. Furthermore, although specific materials and types of materials may be included in the descriptions of example embodiments, one skilled in the art will understand that other materials that achieve the same function can be used. For example, it should be understood that a “metal layer” as described in the examples below can be a layer of any electrically conductive material. 
     In some embodiments, the drive lines and/or sense lines can be formed of other elements including, for example other elements already existing in typical LCD displays (e.g., other electrodes, conductive and/or semiconductive layers, metal lines that would also function as circuit elements in a typical LCD display, for example, carry signals, store voltages, etc.), other elements formed in an LCD stackup that are not typical LCD stackup elements (e.g., other metal lines, plates, whose function would be substantially for the touch sensing system of the touch screen), and elements formed outside of the LCD stackup (e.g., such as external substantially transparent conductive plates, wires, and other elements). For example, part of the touch sensing system can include elements similar to known touch panel overlays. 
     In this example embodiment, each sub-pixels can be a red (R), green (G) or blue (B) sub-pixel, with the combination of all three R, G and B sub-pixels forming one color display pixel. Although this example embodiment includes red, green, and blue sub-pixels, a sub-pixel may be based on other colors of light or other wavelengths of electromagnetic radiation (e.g., infrared) or may be based on a monochromatic configuration.

Metadata:
Filing Date: 20150928
Publication Date: 20190122
Grant Date: 20190122
Priority Date: 20100607
Inventors: HOTELLING, STEVEN P.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F3/0418", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04104", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0443", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0412", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04166", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0418", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F2203/04104", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0418", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 45064094