Patent Publication Number: US-10318050-B2

Title: Touch sensor signal integration

Description:
TECHNICAL FIELD 
     This disclosure generally relates to touch sensors. 
     BACKGROUND 
     According to an example scenario, a touch sensor detects the presence and position of an object (e.g., a user&#39;s finger or a stylus) within a touch-sensitive area of touch sensor of a device. In a touch-sensitive-display application, a touch sensor allows a user to interact directly with what is displayed on a display screen, rather than indirectly with a mouse or touch pad. A touch sensor may be attached to or provided as part of a desktop computer, laptop computer, tablet computer, personal digital assistant (“PDA”), smartphone, satellite navigation device, portable media player, portable game console, kiosk computer, point-of-sale device, or other device. A control panel on a household or other appliance may include a touch sensor. 
     There are a number of different types of touch sensors, such as for example resistive touch sensors, surface acoustic wave touch sensors, and capacitive touch sensors. In one example, when an object physically touches a touch screen within a touch sensitive area of a touch sensor of the touch screen (e.g., by physically touching a cover layer overlaying a touch sensor array of the touch sensor) or comes within a detection distance of the touch sensor (e.g., by hovering above the cover layer overlaying the touch sensor array of the touch sensor), a change in capacitance may occur within the touch screen at a position of the touch sensor of the touch screen that corresponds to the position of the object within the touch sensitive area of the touch sensor. A touch sensor controller processes the change in capacitance to determine the position of the change of capacitance within the touch sensor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates an example system that includes a touch sensor and a controller in accordance with embodiments of the present disclosure 
         FIG. 1B  illustrates an example mechanical stack for a touch sensor in accordance with embodiments of the present disclosure. 
         FIG. 2  illustrates an example dot inverse pixel pattern in accordance with embodiments of the present disclosure. 
         FIG. 3  illustrates an example double dot inverse pixel pattern in accordance with embodiments of the present disclosure. 
         FIG. 4  illustrates an example integration sequence in accordance with embodiments of the present disclosure. 
         FIG. 5  illustrates an example integration sequence mapped onto a dot inverse pattern in accordance with embodiments of the present disclosure. 
         FIG. 6  illustrates an example integration sequence mapped onto a double dot inverse pattern in accordance with embodiments of the present disclosure. 
         FIG. 7  illustrates an example method of performing an integration sequence in accordance with embodiments of the present disclosure. 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
     In one embodiment, a device includes a touch sensor. The touch sensor includes a plurality of electrodes. The device further includes a controller coupled to the touch sensor. The controller includes logic configured, when executed, to cause the controller to perform, among other possible operations, the following: a first positive integration by sensing a first rising edge of a charging signal associated with an electrode of the plurality of electrodes during a first synchronization period, a first negative integration by sensing a first falling edge of the charging signal associated with the electrode of the plurality of electrodes during a second synchronization period, and a first phase shift by skipping integration at the electrode of the plurality of electrodes during a third synchronization period. The first positive integration and the first negative integration are associated with a first sample measurement. The logic is further configured, when executed, to cause the controller to perform the following: a second positive integration by sensing a second rising edge of the charging signal associated with the electrode of the plurality of electrodes during a fourth synchronization period, a second negative integration by sensing a second falling edge of the charging signal associated with the electrode of the plurality of electrodes during a fifth synchronization period, and a second phase shift by skipping integration at the electrode of the plurality of electrodes during a sixth synchronization period. The second positive integration and the second negative integration are associated with a second sample measurement. 
       FIG. 1A  illustrates an example system  100  that includes a touch sensor and a controller in accordance with embodiments of the present disclosure. Touch sensor system  100  comprises a touch sensor  101  and a touch sensor controller  102  that are operable to detect the presence and position of a touch or the proximity of an object within a touch-sensitive area of touch sensor  101 . Touch sensor  101  includes one or more touch-sensitive areas. In one embodiment, touch sensor  101  includes an array of electrodes disposed on one or more substrates, which may be made of a dielectric material. Reference to a touch sensor may encompass both the electrodes of touch sensor  101  and the substrate(s) on which they are disposed. Alternatively, reference to a touch sensor may encompass the electrodes of touch sensor  101 , but not the substrate(s) on which they are disposed. 
     The electrodes of touch sensor  101  include a conductive material forming a shape, such as a disc, square, rectangle, thin line, diamond, other shape, or a combination of these shapes. One or more cuts in one or more layers of conductive material may (at least in part) create the shape of an electrode, and the area of the shape may (at least in part) be bounded by those cuts. In certain embodiments, the conductive material of an electrode occupies approximately 100% of the area of its shape. For example, an electrode may be made of indium tin oxide (ITO) and the ITO of the electrode may occupy approximately 100% of the area of its shape (sometimes referred to as 100% fill). In certain embodiments, the conductive material of an electrode occupies less than 100% of the area of its shape. For example, an electrode may be made of fine lines of metal or other conductive material (FLM), such as for example copper, silver, carbon, or a copper-, silver-, or carbon-based material, and the fine lines of conductive material may occupy only a few percent (e.g., approximately 5%) of the area of its shape in a hatched, mesh, or other pattern. Although this disclosure describes or illustrates particular electrodes made of particular conductive material forming particular shapes with particular fill percentages having particular patterns, this disclosure contemplates electrodes made of any appropriate conductive material forming any appropriate shapes with any appropriate fill percentages having any suitable patterns. 
     The shapes of the electrodes (or other elements) of a touch sensor  101  constitute, in whole or in part, one or more macro-features of touch sensor  101 . One or more characteristics of the implementation of those shapes (such as, for example, the conductive materials, fills, or patterns within the shapes) constitute in whole or in part one or more micro-features of touch sensor  101 . One or more macro-features of touch sensor  101  may determine one or more characteristics of its functionality, and one or more micro-features of touch sensor  101  may determine one or more optical features of touch sensor  101 , such as transmittance, refraction, or reflection. 
     The electrodes of a touch sensor  101  may be configured in any pattern (e.g., a grid pattern or a diamond pattern). Each configuration may include a first set of electrodes and a second set of electrodes. The first set of electrodes and the second set of electrodes overlap to form a plurality of capacitive nodes. In certain embodiments, the first set of electrodes are horizontal and the second set of electrodes are vertical. Although described in particular patterns, the electrodes of touch sensors according to the present disclosure may be in any appropriate pattern. In certain embodiments, for example, the first set of electrodes may be any appropriate angle to horizontal and the second set of electrodes may be any appropriate angle to vertical. This disclosure anticipates any appropriate pattern, configuration, design, or arrangement of electrodes and is not limited to the example patterns discussed above. 
     Although this disclosure describes a number of example electrodes, the present disclosure is not limited to these example electrodes and other electrodes may be implemented. Additionally, although this disclosure describes a number of example embodiments that include particular configurations of particular electrodes forming particular nodes, the present disclosure is not limited to these example embodiments and other configurations may be implemented. In one embodiment, a number of electrodes are disposed on the same or different surfaces of the same substrate. Additionally or alternatively, different electrodes may be disposed on different substrates. Although this disclosure describes a number of example embodiments that include particular electrodes arranged in specific, example patterns, the present disclosure is not limited to these example patterns and other electrode patterns may be implemented. 
     A mechanical stack contains the substrate (or multiple substrates) and the conductive material forming the electrodes of touch sensor  101 . For example, the mechanical stack may include a first layer of optically clear adhesive (OCA) beneath a cover panel. The cover panel may be clear and made of a resilient material for repeated touching, such as for example glass, polycarbonate, or poly (methyl methacrylate) (PMMA). This disclosure contemplates the cover panel being made of any material. The first layer of OCA may be disposed between the cover panel and the substrate with the conductive material forming the electrodes. The mechanical stack may also include a second layer of OCA and a dielectric layer (which may be made of PET or another material, similar to the substrate with the conductive material forming the electrodes). As an alternative, a thin coating of a dielectric material may be applied instead of the second layer of OCA and the dielectric layer. The second layer of OCA may be disposed between the substrate with the conductive material making up the electrodes and the dielectric layer, and the dielectric layer may be disposed between the second layer of OCA and an air gap to a display of a device including touch sensor  101  and touch sensor controller  102 . For example, the cover panel may have a thickness of approximately 1 millimeter (mm); the first layer of OCA may have a thickness of approximately 0.05 mm; the substrate with the conductive material forming the electrodes may have a thickness of approximately 0.05 mm; the second layer of OCA may have a thickness of approximately 0.05 mm; and the dielectric layer may have a thickness of approximately 0.05 mm. 
     Although this disclosure describes a particular mechanical stack with a particular number of particular layers made of particular materials and having particular thicknesses, this disclosure contemplates other mechanical stacks with any number of layers made of any materials and having any thicknesses. For example, in one embodiment, a layer of adhesive or dielectric may replace the dielectric layer, second layer of OCA, and air gap described above, with there being no air gap in the display. 
     One or more portions of the substrate of touch sensor  101  may be made of polyethylene terephthalate (PET) or another material. This disclosure contemplates any substrate with portions made of any material(s). In one embodiment, one or more electrodes in touch sensor  101  are made of ITO in whole or in part. Additionally or alternatively, one or more electrodes in touch sensor  101  are made of fine lines of metal or other conductive material. For example, one or more portions of the conductive material may be copper or copper-based and have a thickness of approximately 5 microns (μm) or less and a width of approximately 10 μm or less. As another example, one or more portions of the conductive material may be silver or silver-based and similarly have a thickness of approximately 5 μm or less and a width of approximately 10 μm or less. This disclosure contemplates any electrodes made of any materials. 
     Touch sensor controller  102  is connected to touch sensor  101  by connection  108  according to an embodiment of the present disclosure. In an embodiment, touch sensor controller  102  is electrically coupled to touch sensor  101  through connection pads  106 . In some embodiments, touch sensor controller  102  includes one or more memory units and one or more processors. In certain of those embodiments, the one or more memory units and the one or more processors are electrically interconnected so that they interdependently operate. The one or more memory units and the one or more processors are electrically coupled to touch sensor  101 , allowing touch sensor  102  to send and receive electrical signals to and from touch sensor  101 . 
     In one embodiment, touch sensor  101  implements a capacitive form of touch sensing. In a mutual-capacitance implementation, touch sensor  101  may include an array of drive and sense electrodes forming an array of capacitive nodes. Touch sensor  101  may have drive electrodes disposed in a pattern on one side of one substrate and sense electrodes disposed in a pattern on one side of another substrate. In such configurations, an intersection of a drive electrode and a sense electrode forms a capacitive node. Such an intersection may be a position where the drive electrode and the sense electrode “cross” or come nearest each other in their respective planes. The drive and sense electrodes forming the capacitive node are positioned near each other but do not make electrical contact with each other. Instead, in response to a signal being applied to the drive electrodes for example, the drive and sense electrodes capacitively couple to each other across a space between them. 
     A charging signal, which is a pulsed or alternating voltage, applied to the drive electrode (by touch sensor controller  102 ) induces a charge on the sense electrode, and the amount of charge induced is susceptible to external influence (such as a touch or the proximity of an object). When an object touches or comes within proximity of the capacitive node, a change in capacitance may occur at the capacitive node and touch sensor controller  102  measures the change in capacitance. By measuring changes in capacitance throughout touch sensor  101 , touch sensor controller  102  determines the position of the touch or proximity within touch-sensitive areas of touch sensor  101 . 
     In a self-capacitance implementation, touch sensor  101  may include an array of electrodes of a single type that may each form a capacitive node. When an object touches or comes within proximity of the capacitive node, a change in self-capacitance may occur at the capacitive node and touch sensor controller  102  measures the change in capacitance, for example, as a change in the amount of charge induced by the charging signal to raise the voltage at the capacitive node by a predetermined amount. As with a mutual-capacitance implementation, by measuring changes in capacitance throughout the array, touch sensor controller  102  determines the position of the touch or proximity within touch-sensitive areas of touch sensor  101 . This disclosure contemplates any form of capacitive touch sensing. 
     Although this disclosure describes particular configurations of particular electrodes forming particular nodes, this disclosure contemplates other configurations of electrodes forming nodes. Moreover, this disclosure contemplates other electrodes disposed on any number of substrates in any patterns. 
     As described above, a change in capacitance at a capacitive node of touch sensor  101  may indicate a touch or proximity input at the position of the capacitive node. Touch sensor controller  102  detects and processes the change in capacitance to determine the presence and position of the touch or proximity input. In one embodiment, touch sensor controller  102  then communicates information about the touch or proximity input to one or more other components (such as one or more central processing units (CPUs)) of a device, which may include touch sensor  101  and touch sensor controller  102 , and which may respond to the touch or proximity input by initiating a function of the device (or an application running on the device). Although this disclosure describes a particular touch sensor controller  102  having particular functionality with respect to a particular device and a particular touch sensor  101 , this disclosure contemplates other touch sensor controllers having any functionality with respect to any device and any touch sensor. 
     In one embodiment, touch sensor controller  102  is implemented as one or more integrated circuits (ICs), such as for example general-purpose microprocessors, microcontrollers, programmable logic devices or arrays, or application-specific ICs (ASICs). Touch sensor controller  102  comprises any combination of analog circuitry, digital logic, and digital non-volatile memory. In one embodiment, touch sensor controller  102  is disposed on a flexible printed circuit (FPC) bonded to the substrate of touch sensor  101 , as described below. The FPC may be active or passive. In one embodiment, multiple touch sensor controllers  102  are disposed on the FPC. 
     In an example implementation, touch sensor controller  102  includes a processor unit, a drive unit, a sense unit, and a storage unit. In such an implementation, the drive unit supplies drive signals to the drive electrodes of touch sensor  101 , and the sense unit senses charge at the capacitive nodes of touch sensor  101  and provides measurement signals to the processor unit representing capacitances at the capacitive nodes. The processor unit controls the supply of drive signals to the drive electrodes by the drive unit and processes measurement signals from the sense unit to detect and process the presence and position of a touch or proximity input within touch-sensitive areas of touch sensor  101 . The processor unit may also track changes in the position of a touch or proximity input within touch-sensitive areas of touch sensor  101 . The storage unit stores programming for execution by the processor unit, including programming for controlling the drive unit to supply drive signals to the drive electrodes, programming for processing measurement signals from the sense unit, and other programming. Although this disclosure describes a particular touch sensor controller  102  having a particular implementation with particular components, this disclosure contemplates touch sensor controller having other implementations with other components. 
     Connecting lines  104 , formed in one example of conductive material disposed on the substrate of touch sensor  101 , couple the drive or sense electrodes of touch sensor  101  to connection pads  106 , also disposed on the substrate of touch sensor  101 . As described below, connection pads  106  facilitate coupling of connecting lines  104  to touch sensor controller  102 . Connecting lines  104  may extend into or around (e.g., at the edges of) touch-sensitive areas of touch sensor  101 . In one embodiment, particular connecting lines  104  provide drive connections for coupling touch sensor controller  102  to drive electrodes of touch sensor  101 , through which the drive unit of touch sensor controller  102  supplies drive signals to the drive electrodes, and other connecting lines  104  provide sense connections for coupling touch sensor controller  102  to sense electrodes of touch sensor  101 , through which the sense unit of touch sensor controller  102  senses charge at the capacitive nodes of touch sensor  101 . 
     Connecting lines  104  are made of fine lines of metal or other conductive material. For example, the conductive material of connecting lines  104  may be copper or copper-based and have a width of approximately 100 μm or less. As another example, the conductive material of connecting lines  104  may be silver or silver-based and have a width of approximately 100 μm or less. In one embodiment, connecting lines  104  are made of ITO in whole or in part in addition or as an alternative to the fine lines of metal or other conductive material. Although this disclosure describes particular tracks made of particular materials with particular widths, this disclosure contemplates tracks made of other materials and/or other widths. In addition to connecting lines  104 , touch sensor  101  may include one or more ground lines terminating at a ground connector (which may be a connection pad  106 ) at an edge of the substrate of touch sensor  101  (similar to connecting lines  104 ). 
     Connection pads  106  may be located along one or more edges of the substrate, outside a touch-sensitive area of touch sensor  101 . As described above, touch sensor controller  102  may be on an FPC. Connection pads  106  may be made of the same material as connecting lines  104  and may be bonded to the FPC using an anisotropic conductive film (ACF). In one embodiment, connection  108  includes conductive lines on the FPC coupling touch sensor controller  102  to connection pads  106 , in turn coupling touch sensor controller  102  to connecting lines  104  and to the drive or sense electrodes of touch sensor  101 . In another embodiment, connection pads  106  are connected to an electro-mechanical connector (such as, for example, a zero insertion force wire-to-board connector). Connection  108  may or may not include an FPC. This disclosure contemplates any connection  108  between touch sensor controller  102  and touch sensor  101 . 
     In certain embodiments, system  100  includes a display stack. The display stack of system  100  may include one or more layers associated with displaying an image to a user. As an example, the display stack may include a layer with elements that apply signals to a pixel layer of the display, a ground layer (also referred to as a common voltage (VCOM) layer), and/or a cover layer. In certain embodiments, the electrodes are placed underneath (from a user&#39;s perspective) pixel rows of the display stack&#39;s pixel layer. This disclosure contemplates the display being any display capable of presenting an image to a user, such as for example a liquid crystal display (LCD), an organic light-emitting diode (OLED) display, etc. In certain embodiments, touch sensor  101  is attached to the display (e.g., an LCD or OLED). In some embodiments, the display of system  100  is an in-cell display module, and touch sensor  101  and controller  102  (e.g., touch sensor circuitry and drive circuitry) are built into the display (e.g., LCD or OLED) module. 
       FIG. 1B  illustrates an example mechanical stack  160  for a touch sensor  101  in accordance with embodiments of the present disclosure. In the example embodiment of  FIG. 1B , the mechanical stack  160  includes multiple layers and is illustrated as positioned with respect to a z-axis. The example mechanical stack  160  includes a display  170 , a second conductive layer  168 , a substrate  166 , a first conductive layer  164 , and a cover layer  162 . 
     In an embodiment, the second conductive layer  168  and first conductive layer  164  are drive and sense electrodes, respectively, as discussed above in connection with  FIG. 1A . In an embodiment, the second conductive layer  168  and first conductive layer  164  are meshes as described in this disclosure. Substrate  166  comprises, in an embodiment, a material which electrically isolates the first and second conductive layers. In an embodiment, substrate  166  provides mechanical support for other layers. In an embodiment, additional layers of substrate (which, for example, may not be the same material as substrate  166 ) may be used in different configurations. For example, a second substrate layer may be located between second conductive layer  168  and display  170 . The display  170  provides display information to be viewed by a user. As an example, display  170  may be an LCD, an OLED, or any other suitable type of display. In an embodiment, display  170  may be an alternating pixel display having subpixels arranged in an alternating pixel display pattern. 
     Cover layer  162  may be clear, or substantially clear, and made of a resilient material for repeated touching, such as for example glass, polycarbonate, or poly(methyl methacrylate) (PMMA). In an embodiment, a transparent or semi-transparent adhesive layer is placed between cover layer  162  and first conductive layer  164 , and/or between second conductive layer  168  and display  170 . A user may interact with touch sensor  101  by touching cover layer  162  using a finger or some other touch object (such as a stylus). A user may also interact with touch sensor  100  by hovering a finger or some other touch object over cover layer  162  without actually making physical contact with cover layer  162 . 
     In the example embodiment of  FIG. 1B , mechanical stack  160  comprises two conductive layers. In an embodiment, mechanical stack  160  may comprise a single conductive layer forming. Other embodiments of mechanical stack  160  may implement other configurations, relations, and perspectives, as well as fewer or additional layers. As one example, one or more of conductive layers  164  and  168  (and/or other layers of mechanical stack  160 ) may be integrated with display  170 , such that the one or more of the conductive layers  164  and  168  are positioned within the layers that form display  170 . In certain embodiments, the layers integrated with display  170  may provide operations for display  170  (e.g., for displaying an image) and for touch sensing. As another example, mechanical stack  160  may include multiple substrates  166 , with first conductive layer  164  being positioned on a first substrate  166  and second conductive layer  168  being positioned on a second substrate  166 . 
       FIG. 2  illustrates an example dot inverse pixel pattern  200  in accordance with embodiments of the present disclosure. Each square of dot inverse pixel pattern  200  represents a pixel. The rows of dot inverse pattern  200  correspond to pixel rows of a pixel layer of a display module of system  100 . For example, row  201  of dot inverse pattern  200  corresponds to a first pixel row, row  202  of dot inverse pattern  200  corresponds to second pixel row, and so on. In certain embodiments, certain electrodes of touch sensor  101  are positioned horizontally underneath pixel rows. For example, a first electrode may be positioned horizontally underneath row  201 , a second electrode may be positioned horizontally underneath adjacent row  202 , and so on. In certain embodiments, a single electrode may cover multiple pixel rows. For example, a first electrode may be positioned horizontally underneath several first pixel rows (e.g., 40 first pixel rows), a second electrode may be positioned horizontally underneath several second pixel rows (e.g., 40 second adjacent rows) adjacent to the first pixel rows, and so on. 
     In certain embodiments, several electrodes are electrically and/or physically coupled together to operate as a single electrode that may cover multiple pixel rows. As an example, a first electrode may include several electrodes positioned horizontally underneath several first pixel rows (e.g., 40 first adjacent rows), a second electrode may include several electrodes positioned horizontally underneath several second pixel rows (e.g., 40 second adjacent rows) adjacent to the first pixel rows, and so on. 
     In certain embodiments, noise generated by a display (e.g., an LCD or OLED) is not constant in time. As an image on the display is refreshed, the noise may follow a repeating pattern of noisy and quieter periods. A display comprising dot inverse pattern  200  may generate at least two types of noise. In the illustrated embodiment, alternating rows  201 ,  203 ,  205 , and so on of dot inverse pattern  200 , as indicated by a forward slash hatch pattern, represent a first type of noise  210  (i.e., a “+ − +” noise pattern), and alternating rows  202 ,  204 ,  206 , and so on of dot inverse pattern  200 , as indicated by a backslash hatch pattern, represent a second type of noise  212  (i.e., a “− + −” noise pattern). The “+” signal represents a positive amplitude peak and the “−” signal represents a negative amplitude peak. In certain embodiments, the degree of change for the positive amplitude peak measured from a zero reference equals the degree of change for the negative amplitude peak measured from a zero reference. 
       FIG. 3  illustrates an example double dot inverse pattern  300  in accordance with embodiments of the present disclosure. Each square of double dot inverse pixel pattern  300  represents a pixel. The rows of double dot inverse pattern  300  correspond to pixel rows of a pixel layer of a display module of system  100 . For example, row  301  of double dot inverse pattern  300  corresponds to a first pixel row, row  302  of double dot inverse pattern  300  corresponds to second pixel row, and so on. A display (e.g., an LCD or OLED) comprising double dot inverse pattern  300  may generate four types of noise. In the illustrated embodiment, rows  301 ,  305 , and  309  of double dot inverse pattern  300 , as indicated by a forward slash hatch pattern, represent a first type of noise  320  (i.e., a “+ − +” regular amplitude pattern), rows  302 ,  306 , and  310  of double dot inverse pattern  300 , as indicated by a double backslash hatch pattern, represent a second type of noise (i.e., a “+ − +” low amplitude pattern), rows  303 ,  307 , and  311  of double dot inverse pattern  300 , as indicated by a forward slash broken line hatch pattern, represent a third type of noise (i.e., a “− + −” regular amplitude pattern), and rows  304 ,  308 , and  312  of double dot inverse pattern  300 , as indicated by a quadruple backslash hatch pattern, represent a fourth type of noise (i.e., a “− +−” low amplitude pattern). In certain embodiments, the degree of change for the positive (+) regular amplitude peak measured from a zero reference equals the degree of change for the negative (−) regular amplitude peak measured from the zero reference. Similarly, the degree of change for the positive (+) low amplitude peak measured from a zero reference equals the degree of change for the negative (−) low amplitude peak measured from the zero reference. 
       FIG. 4  illustrates an example integration sequence in accordance with embodiments of the present disclosure. The integration sequence illustrated in  FIG. 4  may be used by system  100 . In certain embodiments, the integration sequence reduces or eliminates flicker on displays that include certain pixel patterns (e.g., dot inverse pattern  200  and/or double dot inverse pattern  300 ) while reducing or eliminating any reduction in the touch measurement performance.  FIG. 4  shows one synchronization signal  402  and three color signals: red write signal  404 , green write signal  406 , and blue write signal  408 . 
     To update a display of system  100 , controller  102  may use synchronization signals to control the pixels on the display. To facilitate locating by the display controller the position corresponding to each pixel data, controller  102  may use a horizontal synchronization (HSYNC) signal to indicate the start of a pixel line. Essentially, the HSYNC signal acts as a clock signal. For example, a start of a new pixel line can be triggered by the rising edges (e.g., the change from a low level state to a high level state) of the timing pulses of the HSYNC signal. Accordingly, when controller  102  detects the rising edge of one of the timing pulses of the HSYNC signal, the subsequent pixel data received will be interpreted as belonging to the next pixel line. Controller  102  will then update that pixel line. One of ordinary skill in the art will appreciate that in another embodiment, falling edges of the HSYNC pulse can be used by controller  102  to initiate a new pixel line. 
     Synchronization to HSYNC signals may reduce or eliminate display noise in touch measurements. Without this synchronization, charge may be inserted or removed on the pixel capacitor due to the rising and falling edges of a charging signal (e.g., charging signal  410 ), which may cause a fluctuation in capacitor voltage. This fluctuation may result in a change in luminance intensity and/or color intensity (e.g., Red/Green/Blue emitted intensity) of the display. By using HSYNC delay as shown in  FIG. 4 , controller  102  scans during quiet periods when source data is not updating the pixel area (e.g., red write signal  404 , green write signal  406 , and blue write signal  408 ), which may reduce or eliminate display noise. In the embodiment of  FIG. 4 , the range of optimum HSYNC delay is between a falling edge of blue write signal  408  and a rising edge of HSYNC signal  402 , as indicated by notation  412  on  FIG. 4 . 
     In the illustrated embodiment of  FIG. 4 , the rising and falling edges of charging signal  410  driven on one or more electrodes of touch sensor are synchronized to the falling edges of HSYNC signal  402 . In some embodiments, the rising and falling edges of charging signal  410  may be synchronized to the rising edges of HSYNC signal  402 . In certain embodiments, an HSYNC period (e.g., HSYNC period 1) may be in the order of 5 to 15 microseconds. As an example, HSYNC period 1 may be 6.5 microseconds (i.e., 16.6 milliseconds/2560 rows). Measured response signals from HSYNC period 1 and HSYNC period 2 may include measured voltages, time periods, or any other characteristic of the received signals. 
     In  FIG. 4 , controller  102  induces a positively polarized charge on an electrode (e.g., an electrode underlying row  201  of  FIG. 2  or a combination of electrodes underlying several rows  201 ,  202 , etc. of  FIG. 2 ) of touch sensor  101 , which results in charging signal  410  of  FIG. 4 . Controller  102  then performs a positive integration (+) by sensing a first rising edge of charging signal  410  associated with the electrode during HSYNC period 1. Similarly, controller  102  induces a negatively polarized charge on the electrode of touch sensor  101  and performs a negative integration (−) by sensing a first falling edge of charging signal  410  associated with the electrode during HSYNC period 2. By alternating the polarity of applied charging signal  410  between positive and negative polarity for HSYNC periods 1 and 2, touch sensor controller  102  may reduce or eliminate noise since the amount of charge (i.e., noise) injected into system  100  equals the amount of charge (i.e., noise) taken out of system  100 . Two HSYNC periods (e.g., HSYNC period 1 and HSYNC period 2) may be used per measurement cycle. Each measurement cycle is associated with an ADC sample (e.g., ADC sample 1). Touch sensor controller  102  repeats this application and measurement cycle a number of times to accumulate a predetermined number of samples (e.g., ADC samples 1 and 2) from one or more electrodes of touch sensor  101 . 
     In certain embodiments, a touch electrode measurement is performed by averaging two or more samples (e.g., ADC samples 1 and 2). For example, a touch measurement may be performed by averaging four ADC samples that include four positive and negative integration pairs, which may be represented by “+−+−+−+−”. In certain display modules (e.g., an in-cell display module), electrodes may be placed on top and/or underneath one or more pixel rows (e.g., rows  201   a - n  of  FIG. 2 ) of touch sensor  101 . As an example, a display module with 1080 pixel rows may include 27 electrodes. The 27 electrodes may be equally spaced such that each electrode is 40 rows wide. As another example, each electrode may be four rows wide. In certain embodiments, controller  102  performs an integration sequence (e.g., the eight integrations associated with the “+−+−+−+−” integration sequence) sequentially on a first electrode (e.g., an electrode underlying rows  201   a - d  of  FIG. 2 ). The integrations may be synchronized to an HSYNC signal (e.g., HSYNC signal  402  of  FIG. 4 ). After the integrations on the first electrode are completed, controller  102  may then perform the same integration sequence on a second electrode (e.g., a touch electrode underlying rows  201   e - h  of  FIG. 2 ). In certain embodiments, this pattern is repeated until controller  102  performs the integration sequence on the last electrode. 
     While this standard phase shift, HSYNC delay method may reduce display measurement noise under various display backgrounds, it may also cause display flicker on certain pixel layer patterns, such as dot inverse pattern  200  of  FIG. 2  and double dot inverse pattern  300  of  FIG. 3 , since no blanking time, or time when the display is not updating pixels, is available. Types of blanking time include a vertical blanking interval, which may occur between an end of a display frame and a beginning of a next display frame, and a horizontal blanking interval, which may occur between an end of a display row and a beginning of a next display row when no source data is written to the pixels. By creating a gap (0) after every positive integration (+) and negative integration (−), the phase of cross-talk between the display source data and the drive signals of controller  102  can be inversed. This sequence of positive integration (+), negative integration (−), gap (0), positive integration (+), negative integration (−), gap (0), and so forth, which can be represented by “+−0+−0”, may reduce or eliminate flicker without degrading the touch measurement. 
     After performing the first positive integration during HSYNC period 1 and the first negative integration after HSYNC period 2, controller  102  then performs a phase shift during HSYNC period 3 by skipping charge inducement (and integration) on the electrode of touch sensor  101  to reduce or eliminate display flicker, thereby creating a gap (0) at HSYNC period 3. This gap inverses the phase of cross-talk between display source data and charging signal  410 . A first sample measurement (e.g., ADC sample 1 of  FIG. 4 ), which includes HSYNC periods 1 and 2, results in a positive integration (+) for the first type of noise (e.g., noise  210  of  FIG. 2 ) and a negative integration (−) for the second type of noise (e.g., noise  212  of  FIG. 2 ). Thus, an additional sample measurement may be needed to cancel out or significantly reduce the display noise. 
     To obtain ADC sample 2, controller  102  induces a second positively polarized charge on the electrode of touch sensor  101  and performs a second positive integration (+) by sensing a second rising edge of charging signal  410  associated with the electrode during HSYNC period 4. Similarly, controller  102  induces a negatively polarized charge on the electrode of touch sensor  101  and performs a second negative integration (−) by sensing a second falling edge of charging signal  410  associated with the electrode during HSYNC period 5. Controller  102  then performs a phase shift during HSYNC period 6 by skipping charge inducement (and integration) on the electrode to reduce or eliminate display flicker. A second sample measurement (e.g., ADC sample 2 of  FIG. 4 ), which includes HSYNC periods 4 and 5, results in a negative integration (−) for the first type of noise and a positive integration for the second type of noise. Combining ADC samples 1 and 2 results in a positive integration (+) and negative integration (−) for the first type of noise and a positive integration (+) and negative integration (−) for the second type of noise, thereby cancelling out or significantly reducing flicker and display noise within six HSYNC periods. 
       FIGS. 5 and 6  illustrate how the “+−0+−0” sequence reduces or eliminates display noise on a dot inverse pixel pattern and a double dot inverse pixel pattern, respectively, while at the same time reducing display flicker.  FIG. 5  illustrates an example integration sequence mapped onto a dot inverse pattern (e.g., dot inverse pattern  200  of  FIG. 2 ) in accordance with embodiments of the present disclosure. The 12 columns of  FIG. 5  represent 12 consecutive HSYNC periods (HSYNC period 1, HSYNC period 2, HSYNC period 3, and so on). Each HSYNC period is associated with an electrode underlying one or more pixel rows (e.g., one or more pixel rows  201  of  FIG. 2 ) of touch sensor  101 . The pixel rows are associated with two types of noise (e.g., noise  210  and noise  212  of  FIG. 2 ). In the illustrated embodiment of  FIG. 5 , HSYNC periods 1, 3, 5, 7, 9, and 11 are associated with a first type of noise (e.g., first type of noise  210  of  FIG. 2 ), and HSYNC periods 2, 4, 6, 8, 10, and 12 are associated with a second type of noise (e.g., second type of noise  212  of  FIG. 2 ). HSYNC periods 1 through 12 follow the “+−0+−0” integration sequence such that HSYNC periods 1, 4, 7, and 10 represent positive integrations (+), HSYNC periods 2, 5, 8, and 11 represent negative integrations (−), and HSYNC periods 3, 6, 9, and 12 represent skipped integrations (0). This “+−0+−0” integration sequence may cancel out or significantly reduce the two types of display noise, as described below. 
     HSYNC periods 1, 3, and 5, which are associated with the first type of noise, represent a positive integration (+), a skipped integration (0), and a negative integration (−), respectively, thereby cancelling out or significantly reducing the first type of noise (i.e., sum +/0/−=0). HSYNC periods 2, 4, and 6, which are associated with the second type of noise, represent a negative integration (−), a positive integration (+), and a skipped integration (0), thereby cancelling out or significantly reducing the second type of noise (i.e., sum −/+/0=0). Thus, the “+−0+−0” integration sequence may be used to cancel out or significantly reduce noise in displays with a dot inverse pattern within six HSYNC periods and two associated ADC samples (ADC sample 1 associated with HSYNC periods 1 and 2 and ADC sample 2 associated with HSYNC periods 4 and 5). 
     In the illustrated embodiment of  FIG. 5 , the process described above in regard to HSYNC periods 1 through 6 is repeated for HSYNC periods 7 through 12. As shown, HSYNC periods 7, 9, and 11, which are associated with the first type of noise, represent a positive integration (+), a skipped integration (0), and a negative integration (−), respectively, thereby cancelling out or significantly reducing the first type of noise (i.e., sum +/0/−=0). HSYNC periods 8, 10, and 12, which are associated with the second type of noise, represent a negative integration (−), a positive integration (+), and a skipped integration (0), thereby cancelling out or significantly reducing the second type of noise (i.e., sum −/+/0=0). Thus, the “+−0+−0” integration sequence may be used to cancel out or significantly reduce noise in displays with a dot inverse pattern within ADC samples 3 and 4 (ADC sample 3 associated with HSYNC periods 7 and 8 and ADC sample 4 associated with HSYNC periods 10 and 11). 
       FIG. 6  illustrates an example integration sequence mapped onto a double dot inverse pattern (e.g., dot inverse pattern  300  of  FIG. 3 ) in accordance with embodiments of the present disclosure. Similar to  FIG. 5 , the 12 columns of  FIG. 6  represent 12 consecutive HSYNC periods (HSYNC period 1, HSYNC period 2, HSYNC period 3, and so on). However, the HSYNC periods of  FIG. 6  are associated with four types of noise. In the illustrated embodiment of  FIG. 6 , HSYNC periods 1, 5, and 9 are associated with a first type of noise (e.g., first type of noise  320  of  FIG. 3 ), HSYNC periods 2, 6, and 10 are associated with a second type of noise (e.g., second type of noise  322  of  FIG. 3 ), HSYNC periods 3, 7, and 11 are associated with a third type of noise (e.g., third type of noise  324  of  FIG. 3 ), and HSYNC periods 4, 8, and 12 are associated with a fourth type of noise (e.g., fourth type of noise  326  of  FIG. 3 ). HSYNC periods 1, 4, 7, and 10 represent positive integrations (+), HSYNC periods 2, 5, 8, and 11 represent negative integrations (−), and HSYNC periods 3, 6, 9, and 12 represent skipped integrations (−). This “+−0+−0+−0+−0” integration sequence may cancel out or significantly reduce the four types of display noise, as described below. 
     As shown in  FIG. 6 , HSYNC periods 1, 5, and 9, which are associated with the first type of noise, represent a positive integration (+), a negative integration (−), and a skipped integration (0), respectively, thereby cancelling out the first type of noise (i.e., sum +/−/0=0). HSYNC periods 2, 6, and 10, which are associated with the second type of noise, represent a negative integration (−), a skipped integration (0), and a positive integration (+), thereby cancelling out the second type of noise (i.e., sum −/0/+=0). HSYNC periods 3, 7, and 11, which are associated with the third type of noise, represent a skipped integration (0), a positive integration (+), and a negative integration (−), thereby cancelling out the third type of noise (i.e., sum 0/+/−=0). And HSYNC periods 4, 8, and 12, which are associated with the fourth type of noise, represent a positive integration (+), a negative integration (−), and a skipped integration (0), thereby cancelling out the fourth type of noise (i.e., sum +/−/0=0). Thus, the “+−0+−0+−0+−0” integration sequence may be used to cancel out noise in displays with a double dot inverse pattern within 12 HSYNC periods and four ADC samples (ADC sample 1 associated with HSYNC periods 1 and 2, ADC sample 2 associated with HSYNC periods 4 and 5, ADC sample 3 associated with HSYNC periods 7 and 8, and ADC sample 4 associated with HSYNC periods 10 and 11). 
       FIG. 7  illustrates an example method  700  of performing an integration sequence in accordance with embodiments of the present disclosure. Performing integrations in accordance with method  700  may reduce or eliminate flicker and noise associated with a dot inverse pattern of a pixel layer of a touch sensor device. Method  700  may be performed by logic (e.g., hardware or software) of a touch sensor controller (e.g., controller  102  of  FIG. 1A ). For example, method  700  may be performed by executing (with one or more processors of the touch sensor controller) instructions stored in a computer-readable medium of the touch sensor controller. 
     Method  700  represents a “+−0+−0” integration sequence. The method starts at step  705 . At step  710 , a first positive integration (+) is performed by sensing a first rising edge of a charging signal associated with an electrode of a touch sensor of a device during a first synchronization period (e.g., HSYNC period 1 of  FIG. 4 ). Method  700  then moves to step  720 , where a first negative integration (−) is performed by sensing a first falling edge of the charging signal associated with the electrode of the touch sensor during a second synchronization period (e.g., HSYNC period 2 of  FIG. 4 ). The first positive integration (+) and the first negative integration (−) are associated with a first sample measurement (e.g., ADC sample 1 of  FIG. 4 ). At step  730 , a first phase shift is performed by skipping integration (0) at the electrode of the touch sensor during a third synchronization period (e.g., HSYNC period 3 of  FIG. 4 ). In certain embodiments, the electrode comprises several electrodes (e.g., 40 electrodes). For example, 40 electrodes underlying  40  adjacent pixel rows may be electrically and/or physically coupled to form the electrode. 
     At step  740  of method  700 , a second positive integration (+) is performed by sensing a second rising edge of the charging signal associated with the electrode of the touch sensor during a fourth synchronization period (e.g., HSYNC period 4 of  FIG. 4 ). Method  700  then moves to step  750 , where a second negative integration (−) is performed by sensing a second falling edge of the charging signal associated with the electrode of the touch sensor during a fifth synchronization period (e.g., HSYNC period 5 of  FIG. 4 ). The second positive integration (+) and the second negative integration (−) are associated with a second sample measurement (e.g., ADC sample 2 of  FIG. 4 ). At step  760 , a second phase shift is performed by skipping integration (0) at the electrode of the touch sensor during a sixth synchronization period (e.g., HSYNC period 6 of  FIG. 4 ). 
     At step  770 , method  700  determines whether the first, third, and fifth synchronization periods of method  700  are associated with a first type of noise (e.g., noise  210  produced by dot inverse pattern  200  of  FIG. 2 ) and the second, fourth, and sixth synchronization periods of method  700  are associated with a second type of noise (e.g., noise  212  produced by dot inverse pattern  200  of  FIG. 2 ). If the determination at step  770  is affirmative, then method  700  moves to step  780 , where the first and second sample measurements (e.g., ADC sample 1 and ADC sample 2) are summed to cancel out the first type of noise and the second type of noise within the six synchronization periods and a determination is made as to whether a touch has occurred within a touch sensitive area of touch sensor  101 . If the determination at step  770  is negative, method  700  moves to step  785 , where method  700  ends. 
     Method  700  may include more or less steps than those illustrated in  FIG. 7 . For example, step  770  of method  700  may be eliminated if, for instance, the nature of the noise has already been established. Under such circumstances, step  760  of method  700  may proceed directly to step  780 . As another example, while method  700  illustrates “+−0+−0” integration sequence as it relates to two types of noise (e.g., two types of noise produced by a dot inverse pixel pattern), one of ordinary skill in the art will appreciate that in another embodiment, method  700  can be modified to illustrate “+−0+−0+−0+−0” integration sequence as it relates to four types of noise (e.g., noise  320 ,  322 ,  324 , and  326  produced by a double dot inverse pixel pattern  300  of  FIG. 3 ). 
     In certain embodiments, method  700  performs an integration sequence (e.g., the “+−0+−0” integration sequence or the “−−0+−0+−0+−0” integration sequence) on two or more electrodes. As an example, method  700  may perform the “+−0+−0” integration sequence on a first electrode. After the four integrations and two phase shifts of the “+−0+−0” integration sequence are completed on the first electrode, method  700  may then perform the “+−0+−0” integration sequence on a second electrode. Similarly, after the four integrations and two phase shifts of the “+−0+−0” integration sequence are completed on the second electrode, method  700  may perform the “+−0+−0” integration sequence on a third electrode, and so on until method  700  performs the “+−0+−0” integration sequence on all electrodes of the touch sensor. 
     Although this disclosure describes and illustrates particular steps of the method of  FIG. 7  as occurring in a particular order, this disclosure contemplates any steps of the method of  FIG. 7  occurring in any order. An embodiment can repeat or omit one or more steps of the method of  FIG. 7 . Moreover, although this disclosure describes and illustrates an example method of performing an integration sequence including the particular steps of the method of  FIG. 7 , this disclosure contemplates any method of performing an integration sequence including any steps, which can include all, some, or none of the steps of the method of  FIG. 7 . Moreover, although this disclosure describes and illustrates particular components carrying out particular steps of the method of  FIG. 7 , this disclosure contemplates any combination of any components carrying out any steps of the method of  FIG. 7 . 
     Herein, a computer-readable non-transitory storage medium or media may include one or more semiconductor-based or other ICs (such, as for example, field-programmable gate arrays (FPGAs) or ASICs), hard disk drives (HDDs), hybrid hard drives (HHDs), optical discs, optical disc drives (ODDs), magneto-optical discs, magneto-optical drives, floppy diskettes, floppy disk drives (FDDs), magnetic tapes, solid-state drives (SSDs), RAM-drives, SECURE DIGITAL cards or drives, any other suitable computer-readable non-transitory storage media, or any suitable combination of two or more of these. A computer-readable non-transitory storage medium may be volatile, non-volatile, or a combination of volatile and non-volatile. 
     Herein, “or” is inclusive and not exclusive, unless expressly indicated otherwise or indicated otherwise by context. Therefore, herein, “A or B” means “A, B, or both,” unless expressly indicated otherwise or indicated otherwise by context. Moreover, “and” is both joint and several, unless expressly indicated otherwise or indicated otherwise by context. Therefore, herein, “A and B” means “A and B, jointly or severally,” unless expressly indicated otherwise or indicated otherwise by context. 
     This disclosure encompasses a myriad of changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Similarly, the appended claims encompass all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Moreover, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative.