PATENT DOCUMENT

Publication Number: US-9557850-B2
Application Number: US-201514630280-A
Country: US
Kind Code: B2

Title: Dynamic artifact compensation systems and methods

Abstract:
One embodiment describes an electronic display. The electronic display includes display driver circuitry that display an image frame on the electronic device using a first display pixel and a second display pixel, touch sensing circuitry that detect user interaction with the electronic display, and a timing controller. The timing controller receives image data, in which the image data describes a target grayscale value of the first pixel and the second pixel to display the image frame, instructs the display driver circuitry to display a first portion of the image frame by writing the image data to the first display pixel, instructs the touch sensing circuitry to determine whether a user touch is present on a surface of the electronic display after the first portion of the image frame is displayed, determines grayscale value displayed by the second display pixel to display a previous image frame, and instructs the display driver circuitry to display a second portion of the image frame by writing adjusted image data to the second display pixel when the displayed grayscale value differs from the target grayscale value of the second pixel by more than a threshold amount.

Claims:
What is claimed is: 
     
       1. An electronic display, comprising:
 display driver circuitry configured to display an image frame on the electronic display using a first display pixel and a second display pixel; 
 touch sensing circuitry configured to detect user interaction with the electronic display; and 
 a timing controller configured to:
 receive image data, wherein the image data describes a target grayscale value of the first pixel and the second pixel to display the image frame; 
 instruct the display driver circuitry to display a first portion of the image frame by writing the image data to the first display pixel; 
 instruct the touch sensing circuitry to determine whether a user touch is present on a surface of the electronic display after the first portion of the image frame is displayed; 
 determine grayscale value displayed by the second display pixel to display a previous image frame; and 
 instruct the display driver circuitry to display a second portion of the image frame by writing adjusted image data to the second display pixel when the displayed grayscale value differs from the target grayscale value of the second pixel by more than a threshold amount. 
 
 
     
     
       2. The electronic display of  claim 1 , wherein the timing controller is configured to determine the adjusted image data by adjusting the target grayscale value of the second display pixel based at least in part on amount the displayed grayscale value differs from the target grayscale value of the second pixel. 
     
     
       3. The electronic display of  claim 1 , wherein the timing controller is configured to determine the adjusted image data by over-driving the target grayscale value of the second display pixel when the displayed grayscale value is lower than the target grayscale value. 
     
     
       4. The electronic display of  claim 1 , wherein the timing controller is configured to determine the adjusted image data by under-driving the target grayscale value of the second display pixel when the displayed grayscale value is higher than the target grayscale value. 
     
     
       5. The electronic display of  claim 1 , comprising a buffer configured to store the image data, the adjusted image data, and image data written to the second display pixel to display the previous image;
 wherein the timing controller is configured determine the displayed grayscale value of the second display pixel by retrieving the image data written to the second display pixel to display the previous image frame from the buffer. 
 
     
     
       6. The electronic display of  claim 1 , wherein the timing controller is configured to instruct the display comments to stop writing image data to display pixels while the touch sensing circuitry determine whether the user touch is present on a surface of the electronic display. 
     
     
       7. The electronic display of  claim 1 , wherein the touch sensing circuitry comprise a touch sensing pixel configured to detect presences and position of the user touch based at least in part on an impedance change at the touch sensing pixel. 
     
     
       8. A tangible, non-transitory, computer readable medium storing instructions executable by a processor of an electronic display configured to display an image frame, wherein the instructions comprise instructions to:
 receive, using the processor, image data corresponding with the image frame; 
 instruct, using the processor, the electronic display to write the image data to display pixels in the electronic display to display a portion of the image frame; 
 instruct, using the processor, the electronic display to pause writing the image data once the portion of the image frame is displayed; 
 adjust, using the processor, the image data due to the pause by adjusting grayscale value of the image data; 
 instruct, using the processor, the electronic display to write the adjusted image data to the display pixels after the pause. 
 
     
     
       9. The computer readable medium of  claim 8 , comprising instructions to instruct, using the processor, the electronic display to determine whether a user touch is present on a surface of the electronic display during the pause. 
     
     
       10. The computer readable medium of  claim 8 , wherein the pause causes a delay between writing the image data and writing the adjusted image data to the display pixels. 
     
     
       11. The computer readable medium of  claim 8 , wherein the instruction to adjust the image data comprises instructions to over-drive the grayscale value of the image data or under-drive the grayscale value of the image data. 
     
     
       12. A method comprising:
 writing a first set of grayscale values to a first row of display pixels on an electronic display to display a first portion of a first image frame; 
 writing a second set of grayscale values to a second row of the display pixels to display a first portion of a second image frame while the first portion of the first image frame is displayed; 
 receiving a first user input after the first portion of the second image frame is displayed via a user input device; 
 writing a third set of grayscale values to the first row of display pixels to display a second portion of the second image frame after receiving the first user input, wherein the third set of grayscale values is determined based at least in part on difference between the first set of grayscale values and a fourth set of grayscale values received from an image source, wherein the fourth set of grayscale values indicates desired brightness level of the first row of display pixels when the second image frame is displayed. 
 
     
     
       13. The method of  claim 12 , comprising:
 writing a fifth set of grayscale values to a third row of display pixels on an electronic display to display a second portion of the first image frame; 
 receiving a second user input after the second portion of the second image frame is displayed via the user input device; 
 writing a sixth set of grayscale value to the third row of display pixels to display a third portion of the second image frame after receiving the second user input, wherein the sixth set of grayscale values is determined based at least in part on difference between the fifth set of grayscale values and a seventh set of grayscale values received from the image source, wherein the seventh set of grayscale values indicates desired brightness level of the third row of display pixels when the second image frame is displayed. 
 
     
     
       14. The method of  claim 12 , wherein the third set of grayscale values increases at a faster rate than the fourth set of grayscale values when the first set of grayscale values is lower than the fourth set of grayscale values. 
     
     
       15. The method of  claim 12 , wherein the third set of grayscale values decreases at a faster rate than the fourth set of grayscale values when the first set of grayscale values is higher than the fourth set of grayscale values. 
     
     
       16. The method of  claim 12 , comprising storing the third set of grayscale values in a buffer to enable the third set of grayscale values to be determined when a third image frame is displayed immediately after the second image frame. 
     
     
       17. The method of  claim 12 , wherein the user input device comprises a touch sensing pixel in the electronic display, wherein the touch sensing pixel is configured to determine occurrence and position of the first user input on a surface of the electronic display. 
     
     
       18. A tangible, non-transitory, computer readable medium storing instructions executable by a processor of an electronic display configured to successively display a first image frame and a second image frame, wherein the instructions comprise instructions to:
 detect, using the processor, a first intra-frame pause; 
 determine, using the processor, grayscale value displayed by a first display pixel displaying the first image frame during the first intra-frame pause; 
 determine, using the processor, a target grayscale value of the first display pixel to display the second image frame; 
 determine, using the processor, a first adjusted grayscale value when the displayed grayscale value of the first display pixel differs from a target grayscale value of the first display pixel by more than a threshold amount, wherein the first adjusted grayscale value is written to the first display pixel after the first intra-frame pause to enable the second image frame to be perceived as desired. 
 
     
     
       19. The computer readable medium of  claim 18 , comprising instructions to determine occurrence and position of a user touch on a surface of the electronic display during the first intra-frame pause. 
     
     
       20. The computer readable medium of  claim 18 , comprising instructions to:
 detect, using the processor, a second intra-frame pause; 
 determine, using the processor, grayscale value displayed by a second display pixel displaying the first image frame during the second intra-frame pause; 
 determine, using the processor, a target grayscale value of the second display pixel to display the second image frame; 
 determine, using the processor, a second adjusted grayscale value when the displayed grayscale value of the second display pixel differs from a target grayscale value of the second display pixel by more than the threshold amount, wherein the second adjusted grayscale value is written to the second display pixel after the second intra-frame pause to enable the second image frame to be perceived as desired. 
 
     
     
       21. The computer readable medium of  claim 18 , wherein the adjusted grayscale values increase at a faster rate than the target grayscale value when desired brightness level of the second image frame is higher than desired brightness level of the first image frame. 
     
     
       22. The computer readable medium of  claim 18 , wherein the adjusted grayscale values decreases at a faster rate than the target grayscale value when desired brightness level of the second image frame is lower than desired brightness level of the first image frame. 
     
     
       23. The computer readable medium of  claim 18 , wherein perceived brightness level of the first display pixel when the first adjusted grayscale value is written to the first display pixel after the first intra-frame pause is equal to perceived brightness level of the first display pixel when the target grayscale value is written to the first display pixel without the first intra-frame pause. 
     
     
       24. A timing controller in a touch-sensitive electronic display configured to successively display a first image frame and a second image frame, comprising:
 a comparator configured to determine whether a target grayscale value differs from a displayed grayscale value by more than a threshold amount, wherein the displayed grayscale value is a grayscale value stored by a display pixel to display the first image frame during an intra-frame pause and the target grayscale value is a grayscale value of the display pixel corresponding with the second image frame; and 
 a grayscale adjustment look-up table configured to determine an adjusted grayscale value when the displayed grayscale value differs from the target grayscale value by more than the threshold amount, wherein the adjusted grayscale value is determined based at least in part on amount the target grayscale value and the displayed grayscale value differ, wherein the adjusted grayscale value is written to the display pixel after the intra-frame pause to display the second image frame as desired. 
 
     
     
       25. The timing controller of  claim 24 , wherein the timing controller is configured to instruct a touch sensing pixel to determine whether a user touch is present on a surface of the electronic display during the intra-frame pause. 
     
     
       26. The timing controller of  claim 24 , wherein the grayscale adjustment look-up table and the threshold amount are predetermined and stored in memory in the timing controller. 
     
     
       27. The timing controller of  claim 24 , comprising a buffer configured to store the displayed grayscale value, the target grayscale value, and the adjusted grayscale value.

Description:
BACKGROUND 
     The present disclosure relates generally to electronic displays, and more particularly, to artifact compensation for touch-sensitive electronic displays. 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     Generally, an electronic display may enable information to be communicated to a user by displaying visual representations of the information, for example, as pictures, text, or videos. More specifically, the visual representations may be displayed as successive static image frames. In some embodiments, each image frame may be displayed by successively writing image data to rows of pixels in the electronic display. 
     In addition to outputting information, the electronic display may enable the user to communicate information to the electronic display and/or a computing system that includes the electronic display. For example, the electronic display may be a touch-sensitive display, which may detect a user touch on the surface of the electronic display. More specifically, the electronic display may detect occurrence and/or position of the user touch based at least in part on an impedance (e.g., capacitance) change in the electronic display caused by the user touch. 
     However, at any given time, the electronic display may generally either write image data to the display pixels or check for an impedance change via touch sensing, but not both. Thus, when image data is being written to the pixels, a user touch may be undetected. Similarly, when checking for impedance changes via touch sensing, the electronic display may stop writing image data. As such, in operation, the electronic display may alternate between writing image data to the pixels and checking for a user touch. Moreover, the touch detection accuracy may depend at least in part on frequency the electronic display checks for impedance changes. Punctuating the writing of the image data with a greater number of touch sensing impedance checks, however, could introduce perceivable artifacts. 
     SUMMARY 
     A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below. 
     The present disclosure generally relates to improving touch detection accuracy of touch-sensitive electronic displays. More specifically, the touch detection accuracy may be improved by increasing frequency an electronic display checks for a user touch. In fact, the electronic display may alternate between writing portions of image frames with checking for user touch. For example, the electronic display may write a first portion of an image frame to pixels in the electronic display, pause the writing of the image frame, check for a user touch, and write a second portion of the image frame to the pixels. As used herein, pausing the writing of an image frame to check for a user touch is generally referred to as an “intra-frame pause.” 
     However, pausing in the middle writing of an image frame may cause perceivable visual artifacts on the electronic display, particularly when the desired brightness level (e.g., grayscale value) between successively displayed image frames is changing. More specifically, an intra-frame pause may cause a small delay between writing the first portion of the image frame and writing the second portion of the image frame. In some embodiments, when the successively displayed image frames are changing brightness level (e.g., grayscale value), the delay may cause the brightness of the second portion to be perceptively different from the first portion even when both portions are supposed to be displaying the same brightness level. For example, when the brightness is increasing, the second portion may be displayed darker than desired. On the other hand, when the brightness is decreasing, the second portion may be displayed brighter than desired. 
     Accordingly, in some embodiments, the image data written to the pixels after an intra-frame pause may be adjusted to compensate for the intra-frame pause. For example, when the electronic display determines that the desired brightness level of the current image frame is increasing from the previous image frame by more than a threshold amount, the grayscale value of the image data written to the pixels after the intra-frame may be over-driven (e.g., increased). On the other hand, when the electronic display determines that the desired brightness level of the current image frame is decreasing from the previous frame by more than a threshold amount, the grayscale value of the image data written to the pixels after the intra-frame pause may be under-driven (e.g., decreased). In this manner, since a human eye generally averages the brightness level of a pixel over short durations of time (e.g., time to write one image frame), adjusting the grayscale value of the image data written to pixels (e.g., by over-driving or under-driving) after an intra-frame pause may enable brightness level of the pixel to be perceived as desired. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  is a block diagram of a computing device, in accordance with an embodiment; 
         FIG. 2  is an example of the computing device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 3  is an example of the computing device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 4  is an example of the computing device of  FIG. 1 , in accordance with an embodiment; 
         FIG. 5  is block diagram of a portion of the computing device of  FIG. 1  used to display images and sense user touch, in accordance with an embodiment; 
         FIG. 6  is a schematic diagram of display components of an electronic display, in accordance with an embodiment; 
         FIG. 7  is a schematic diagram of touch sensing components of the electronic display, in accordance with an embodiment; 
         FIG. 8  is a timing diagram used by the portion of the computing device of  FIG. 5  to write image frames and sense user touch, in accordance with an embodiment; 
         FIG. 9A  is a plot of grayscale value of a pixel before an intra-frame pause compared to a pixel after the intra-frame pause, in accordance with an embodiment; 
         FIG. 9B  is a plot of the difference between a target grayscale value and an actual grayscale value for the pixel before the intra-frame pause and the pixel after the intra-frame pause, in accordance with an embodiment; 
         FIG. 10A  is a plot of grayscale value of the pixel before an intra-frame pause compared to the pixel after the intra-frame pause with artifact compensation, in accordance with an embodiment; 
         FIG. 10B  is a zoomed-in view of a portion of the plot of  FIG. 10A , in accordance with an embodiment; 
         FIG. 11  is a block diagram of a control logic used to perform artifact compensation, in accordance with an embodiment; 
         FIG. 12  is a flow diagram of a process for performing artifact compensation, in accordance with an embodiment; 
         FIG. 13A  illustrates successively displayed image frames with increasing brightness levels, in accordance with an embodiment; 
         FIG. 13B  illustrates the image frames of  FIG. 13A  with a first embodiment of artifact compensation, in accordance with an embodiment; 
         FIG. 13C  illustrates the image frames of  FIG. 13A  with a second embodiment of artifact compensation, in accordance with an embodiment; 
         FIG. 14A  illustrates successively displayed image frames with decreasing brightness levels, in accordance with an embodiment; 
         FIG. 14B  illustrates the image frames of  FIG. 14A  with a first embodiment of artifact compensation, in accordance with an embodiment; and 
         FIG. 14C  illustrates the image frames of  FIG. 14A  with a second embodiment of artifact compensation, in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     One or more specific embodiments of the present disclosure will be described below. These described embodiments are only examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but may nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. 
     As mentioned above, a touch-sensitive electronic display may enable both the output of information to a user from a computing system as well as the input of control commands from the user to the computing system. More specifically, the electronic display may write image data to pixels to display visual representations of the information. Additionally, the electronic display may detect a user touch by checking for changes in impedance (e.g., capacitance) caused by the user touch on the surface of the electronic display. 
     Generally, an electronic display may alternate between writing image data and checking for a user touch. For example, the electronic display may write an entire image frame to the display pixels, check for a user touch, and repeat. However, at one time, the electronic display may only perform one of writing image data or checking for impedance changes, but not both. In other words, when the electronic display is writing image data to the pixels, a user touch during that period may go undetected. 
     Accordingly, to improve the user touch detection, the frequency the electronic display checks for a user touch may be increased. For example, the electronic display may write a first portion of an image frame, pause the writing of the image frame, check for an impedance change, write a second portion of the image frame, pause the writing of the image frame, check for an impedance change, and so on. As used herein, pausing the writing of an image frame to check for a user touch is generally referred to as an “intra-frame pause.” In this manner, intra-frame pauses may enable the frequency the electronic display checks for a user touch to be increased, which may improve user touch detection accuracy. 
     However, the intra-frame pause between writing portions of an image frame may cause perceivable visual artifacts. As will be desired in more detail below, artifacts may be more likely perceivable when successively displayed image frames are changing in desired brightness level. More specifically, an intra-frame pause may cause a delay in writing image data to a pixel written after the intra-frame pause. Thus, when the brightness level is changing, the delay may cause the brightness level to change by a less than desired amount. For example, when the brightness is increasing, the pixel may be displayed darker than desired. On the other hand, when the brightness is decreasing, the pixel may be displayed brighter than desired. 
     Accordingly, one embodiment of the present disclosure describes an electronic display that reduces the likelihood of perceivable visual artifacts by compensating for an intra-frame pause. As will be described in more detail below, the electronic display may include a timing controller (TCON) that compares the successively displayed image frames. More specifically, the timing controller may compare the desired brightness level for the current image frame with the displayed brightness level of the previous image frame. When the desired brightness level differs from the displayed brightness level by more than a threshold amount, the timing controller may adjust the grayscale value of the image data written to pixels after an intra-frame pause so that the pixels may be perceived by a user at the desired brightness level. For example, when the desired brightness level is greater than the displayed brightness level by more than the threshold amount, the timing controller may over-drive (e.g., increase) the grayscale value of the image data written to the pixels after the intra-frame pause. On the other hand, when the desired brightness level is less than the displayed brightness level by more than the threshold 
     In perceiving the visual representations displayed on the electronic display, a user&#39;s eyes generally averages the brightness level of a pixel across a short period of time (e.g., time used to write an image frame). As such, the user&#39;s eyes may average out undesired brightness levels caused by the intra-frame pause with the adjusted brightness level to perceive the desired brightness levels. Thus, the techniques described herein may enable an electronic display to improve user touch detection accuracy while minimizing the likelihood of perceivable visual artifacts. To help illustrate, a computing device  10  that utilizes a touch-sensitive electronic display  12  is described in  FIG. 1 . As will be described in more detail below, the computing device  10  may be any suitable computing device, such as a handheld computing device, a tablet computing device, a notebook computer, and the like. 
     Accordingly, as depicted, the computing device  10  includes the display  12 , input structures  14 , input/output (I/O) ports  16 , one or more processor(s)  18 , memory  20 , nonvolatile storage  22 , a network interface  24 , and a power source  26 . The various components described in  FIG. 1  may include hardware elements (including circuitry), software elements (including computer code stored on a non-transitory computer-readable medium), or a combination of both hardware and software elements. It should be noted that  FIG. 1  is merely one example of a particular implementation and is intended to illustrate the types of components that may be present in the computing device  10 . Additionally, it should be noted that the various depicted components may be combined into fewer components or separated into additional components. For example, the one or more processors  18  may include a graphical processing unit (GPU). 
     As depicted, the processor  18  is operably coupled with memory  20  and/or nonvolatile storage device  22 . More specifically, the processor  18  may execute instruction stored in memory  20  and/or non-volatile storage device  22  to perform operations in the computing device  10 , such as outputting image data to the display  12 . As such, the processor  18  may include one or more general purpose microprocessors, one or more application specific processors (ASICs), one or more field programmable logic arrays (FPGAs), or any combination thereof. Additionally, memory  20  and/or non volatile storage device  22  may be a tangible, non-transitory, computer-readable medium that stores instructions executable by and data to be processed by the processor  18 . In other words, the memory  20  may include random access memory (RAM) and the non-volatile storage device  22  may include read only memory (ROM), rewritable flash memory, hard drives, optical discs, and the like. By way of example, a computer program product containing the instructions may include an operating system or an application program. 
     Additionally, as depicted, the processor  18  is operably coupled with the network interface  24  to communicatively couple the computing device  10  to a network. For example, the network interface  24  may connect the computing device  10  to a personal area network (PAN), such as a Bluetooth network, a local area network (LAN), such as an 802.11x Wi-Fi network, and/or a wide area network (WAN), such as a 4G or LTE cellular network. Furthermore, as depicted, the processor  18  is operably coupled to the power source  26 , which provides power to the various components in the computing device  10 . As such, the power source  26  may include any suitable source of energy, such as a rechargeable lithium polymer (Li-poly) battery and/or an alternating current (AC) power converter. 
     As depicted, the processor  18  is also operably coupled with I/O ports  16 , which may enable the computing device  10  to interface with various other electronic devices, and input structures  14 , which may enable user interaction with the computing device  10 . Accordingly, the inputs structures  14  may include buttons, keyboards, mice, trackpads, and the like. In addition to the input structures  14 , the display  12  may include touch sensing components to enable user inputs via user touches to the surface of the display  12 . In fact, in some embodiments, the electronic display  12  may detect multiple user touches at once. 
     In addition to enabling user inputs, the display  12  may display visual representations via one or more static image frames. In some embodiments, the visual representations may be a graphical user interface (GUI) for an operating system, an application interface, text, a still image, or a video. As depicted, the display  12  is operably coupled to the processor  18 , which may enable the processor  18  (e.g., image source) to output image data to the display  12 . 
     Based on the received image data, the display  12  may then write image frames to the display pixels in the display  12  to display a visual representation. As will be described in more detail below, once the display  12  receives the image data, additional processing may be performed on the image data to further improve the accuracy of the viewed visual representation. For example, the display  12  may adjust the grayscale value of the image data before writing the image data to the pixels to reduce the likelihood of perceivable visual artifacts caused by an intra-frame pause. 
     As described above, the computing device  10  may be any suitable electronic device. To help illustrate, one example of a handheld device  10 A is described in  FIG. 2 , which may be a portable phone, a media player, a personal data organizer, a handheld game platform, or any combination of such devices. For example, the handheld device  10 A may be any iPhone model from Apple Inc. of Cupertino, Calif. 
     As depicted, the handheld device  10 A includes an enclosure  28 , which may protect interior components from physical damage and to shield them from electromagnetic interference. The enclosure  28  may surround the display  12 , which, in the depicted embodiment, displays a graphical user interface (GUI)  30  having an array of icons  32 . By way of example, when an icon  32  is selected either by an input structure  14  or a touch sensing component of the display, an application program may launch. 
     Additionally, as depicted, input structure  14  may open through the enclosure  28 . As described above, the input structures  14  may enable a user to interact with the handheld device  10 A. For example, the input structures  14  may activate or deactivate the handheld device  10 A, navigate a user interface to a home screen, navigate a user interface to a user-configurable application screen, activate a voice-recognition feature, provide volume control, and toggle between vibrate and ring modes. Furthermore, as depicted, the I/O ports  16  open through the enclosure  28 . In some embodiments, the I/O ports  16  may include, for example, an audio jack to connect to external devices. 
     To further illustrate a suitable computing device  10 , a tablet device  10 B is described in  FIG. 3 , such as any iPad model available from Apple Inc. Additionally, in other embodiments, the computing device  10  may take the form of a computer  10 C as described in  FIG. 4 , such as any MacBook or iMac model available from Apple Inc. As depicted, the computer  10 C also includes a display  12 , input structures  14 , I/O ports  16 , and a housing  28 . 
     As described above, the display  12  may facilitate communication of information between the computing system  10  and a user, for example, by displaying visual representations based on image data received from the processor  18  and detecting user touch on the surface of the display  12 . To help illustrate, a portion  34  of the computing device  10  is described in  FIG. 5 . As depicted, the processor  18  and the display  12  are communicatively coupled via a data bus  36 , which may enable the processor  18  to transmit image data to the display  12  indicating occurrence and/or position of a user touch to the processor  18 . 
     To facilitate such operations, the display  12  may include display components (e.g., display driver circuitry)  38  and touch sensing components (e.g., touch sensing circuitry)  40 . More specifically, the display components  38  may include any suitable components used to display an image frame on the display  12 . For example, when the display  12  is a liquid crystal display, the display components  38  may include a thin film transistor (TFT) layer and a liquid crystal layer organized as display pixels. To help illustrate, operation of display components  38  used in a liquid crystal display are described in  FIG. 6 . 
     In the depicted embodiment, the display components  38  include a number of display pixels  42  disposed in a pixel array or matrix. More specifically, each display pixel  42  may be defined at the intersection of a gate line  44  (e.g. scanning line) and a source lines  106  (e.g., data line). Although only six display pixels  42 , referred to individually by the reference numbers  42 A- 42 F, are shown for purposes of simplicity, it should be understood that in an actual implementation, each source line  46  and gate line  44  may include hundreds or thousands of such display pixels  42 . 
     As described above, image data may be written to each of the display pixels  42  to display an image frame. More specifically, image data may be written to a display pixel  42  by using a thin film transistor  48  to selectively store an electrical potential (e.g., voltage) on a respective pixel electrode  50 . Accordingly, in the depicted embodiment, each thing film transistor  48  includes a source  54 , which is electrically connected to a source line  46 , a drain  56 , which is electrically connected to a pixel electrode  50 , and a gate  58 , which is electrically connected to a gate line  44 . 
     Thus, to write image data to a row of display pixels  42  (e.g.,  42 A- 42 C), the corresponding gates  48  may be activated (e.g., turned on) by a scanning signal on the gate line  44 . Image data may then be written to the row of display pixels by storing an electrical potential corresponding with the grayscale value of the image data from the source lines  46  to the pixel electrode  50 . The potential stored on the pixel electrode  50  relative to a potential of a common electrode  52  may then generate an electrical field sufficient to alter the arrangement of the liquid crystal layer (not shown). More specifically, this electrical field may align the liquid crystal molecules within the liquid crystal layer to modulate light transmission through the display pixel  42 . In other words, as the electrical field changes, the amount of light passing through the display pixel  42  may increase or decrease. As such, the perceived brightness level of the display pixel  42  may be varied by adjusting the grayscale value of the image data. In this manner, an image frame may be displayed by successively writing image data the rows of display pixels  42 . 
     To facilitate writing image data to the display pixels  42 , the display components  38  may also include a source driver  60 , a gate driver  62 , and a common voltage (Vcom) source  64 . More specifically, the source driver  60  may output the image data (e.g., as an electrical potential) on the source lines  46  to control electrical potential stored in the pixel electrodes  50 . Additionally, the gate driver  62  may output a gate signal (e.g., as an electrical potential) on the gate lines  44  to control activation of rows of the display pixels  42 . Furthermore, the Vcom source  64  may provide a common voltage to the common electrodes  52 . 
     Similarly, the touch sensing components  40  may include any suitable components used to detect occurrence and/or presence of a user touch on the surface of the display  12 . To help illustrate, operation of touch sensing components  40  that may be used in a capacitive touch sensitive display  12  are described in  FIG. 7 . 
     In the depicted embodiment, the touch sensing components  40  include a number of touch pixels  66  disposed in a pixel array or matrix. More specifically, each touch pixel  66  may be defined at the intersection of a touch drive line  68  and a touch sense line  70 . Although only six touch pixels  66  are shown for purposes of simplicity, it should be understood that in an actual implementation, each touch drive line  68  and touch sense line  70  may include hundreds or thousands of such touch pixels  66 . 
     As described above, occurrence and/or position of a user touch may be detected based on impedance changes caused by the user touch. To facilitate detecting impedance changes, the touch sensing components  40  may include touch drive logic  72  and touch sense logic  74 . More specifically, the touch drive logic  72  may output touch drive signals at various frequencies and/or phases on the touch drive lines  68 . When an object, such as a user finger, contacts the surface of the display  12 , the touch sense lines  70  may respond differently to the touch drive signals, for example by changing impedance (e.g., capacitance). More specifically, the touch sense lines  70  may generate touch sense signals to enable the touch sense logic  74  to determine occurrence and/or position of the object on the surface of the display  12 . 
     In some embodiments, the touch sensing components  40  may utilize dedicated touch drive lines  68 , dedicated touch sense lines  70 , or both. Additionally or alternatively, the touch drive lines  68  and/or the touch sense lines  70  may utilize one or more of the display components  38 . For example, the touch drive lines  68  and/or the touch sense lines  70  may be formed from one or more gate lines  44 , one or more pixel electrodes  50 , one or more common electrodes  52 , one or more source lines  46 , or any combination thereof. 
     To facilitate controlling operation of both the display components  38  and the touch sensing components  40 , the display  12  may include a timing controller (TCON)  76  as depicted in  FIG. 5 . Accordingly, the timing controller  76  may include a processor  78  and memory  80 . More specifically, the processor  78  may execute instruction stored in memory  80  to perform operations in the display  12 . Additionally, memory  80  may be a tangible, non-transitory, computer-readable medium that stores instructions executable by and data to be processed by the processor  78 . 
     For example, the timing controller  76  may instruct the display components  38  to write image data to the display pixels  42  and instruct the touch sensing components  40  to check for a user touch. As described above, the frequency the touch sensing components  40  detects whether a user touch is present may be increased to improve the user touch detection accuracy. In fact, the timing controller  76  may utilize intra-frame pauses by alternating between instructing the display components  38  to write a portion of an image frame and instructing the touch sensing components  40  to check for a user touch. 
     To help illustrate, a timing diagram illustrating the operation of the electronic display  12  is described in  FIG. 8 . More specifically,  FIG. 8  describes operation of the display components  38  with a write timing plot  79  and operation of the touch sensing components  40  with a touch sensing timing plot  81  during a period when three image frames are displayed. 
     For the purpose of description, a first image frame is written between t 0  and t 8 , a second image frame is written between t 8  and t 9 , and a third image frame is written between t 9  and t 10 . In the depicted embodiment, each image frame may be written in four separate portions. For example, between t 0  and t 1 , the timing controller  76  may instruct the display components  38  to write a first portion of the first image frame to a quarter of the pixels  42 . Between t 1  and t 2 , the timing controller  76  may instruct the display components  38  to pause writing the first image frame and instruct the touch sensing components  40  to check for a user touch. Between t 2  and t 3 , the timing controller  76  may instruct the display components  38  to write a second portion of the first image frame to a quarter of the pixels  42 . Between t 3  and t 4 , the timing controller  76  may again instruct the display components  38  to pause writing the first image frame and instruct the touch sensing components  40  to check for a user touch. Between t 4  and t 5 , the timing controller  76  may instruct the display components  38  to write a third portion of the first image frame to a quarter of the pixels  42 . Between t 5  and t 6 , the timing controller  76  may again instruct the display components  38  to pause writing the first image frame and instruct the touch sensing components  40  to check for a user touch. Between t 6  and t 7 , the timing controller  76  may instruct the display components  38  to write a fourth portion of the first image frame to a quarter of the pixels  42 . Between t 7  and t 8 , the timing controller  76  may again instruct the touch sensing components  40  to check for a user touch. 
     As described above, an intra-frame pause may occur when the display  12  pauses writing an image frame to check for a user touch. Accordingly, the time periods from t 1  to t 2 , t 3  to t 4 , and t 5  to t 6  may each be referred to as an intra-frame pause. As depicted, the intra-frame pauses enable the frequency with which the display  12  checks for a user touch to be increased. For example, in the depicted embodiment, the display  12  may check for a user touch four times during the time period one image frame is written. Generally, the number intra-frame pauses used may be based on desired user touch detection accuracy. For example, the number of intra-frame pauses may be increased to improve user touch detection accuracy. As such, writing of an image frame may be divided by any suitable manner (e.g., 1, 2, 3, 4, 5, or more intra-frame pauses). 
     However, as described above, an intra-frame pause may also potentially cause a perceivable visual artifact, such as pixels being perceived at an undesired brightness level. To help illustrate, the grayscale value (e.g., brightness level) for two display pixels  42  in display  12  is described in  FIG. 9A . More specifically,  FIG. 9A  is a plot that describes the grayscale value of a first pixel, which is written before an intra-frame pause, with a first grayscale curve  82  and the grayscale value of a second pixel, which is written after an intra-frame pause, with a second grayscale curve  84  over a period of operation between 0 to 150 ms, in which time is shown on the X-axis and relative grayscale value (e.g., brightness level) is shown on the Y-axis. 
     To simplify the following discussion, the techniques are described using image frames with a single intra-frame pause and with the same desired brightness level for each display pixel  42 . In the depicted embodiment, the image frames displayed from 0 to 50 ms have a brightness level of 5% (e.g., grayscale value of 64). At 50 ms, the desired brightness level of the image frame is increased from the previously displayed image frames. As such, the grayscale value of the image data written to the first pixel and the second pixel are increased. 
     More specifically, as described by the first grayscale curve  82 , the grayscale value of the image data written to the first pixel begins to be increased at 50 ms or very shortly thereafter. On the other hand, as described by the second grayscale curve  84 , the grayscale value of the image data written to the second pixel begins to increase after an intra-frame pause  86 , which may enable the display  12  to check for a user touch between writing image data to the first pixel and the second pixel. As depicted, the intra-frame pause  86  causes the grayscale value change of the second pixel to lag behind the first pixel. As such, the perceived brightness level of the second pixel may be less than the perceived brightness level of the first pixel. 
     Since an intra-frame pause is generally very short in duration (e.g., 1 or 2 ms), the intra-frame pause may only cause a perceivable brightness difference (e.g., visual artifact) when the desired brightness level is changing by more than a threshold amount. For example, in the depicted embodiment, another intra-frame pause  88  occurs at approximately 25 ms. However, since the desired brightness level is not changing, the intra-frame pause  88  does not cause a perceivable visual artifact. On the other hand, since the desired brightness level is changing at 50 ms, the intra-frame pause  86  may cause a perceivable visual artifact. 
     To help illustrate, the grayscale value difference between the first pixel and the second pixel is described in  FIG. 9B . More specifically,  FIG. 9B  is a plot that describes the difference between a target grayscale value and the grayscale value of the first pixel with a first difference curve  90  and difference between the target grayscale value and the grayscale value of the second pixel with a second difference curve  92  over the period of operation, in which time is shown on the X-axis and grayscale difference is shown on the Y-axis. As used herein, the “target grayscale value” may be the grayscale value of image data received from the image source. In other words, when the target grayscale value is written to a display pixel without an intra-frame pause, the display pixel may be at its desired brightness level. 
     As depicted, between 0 to 50 ms, the grayscale value of the first pixel and the second pixel are generally as desired. As such, the first pixel and the second pixel may be perceived at the desired brightness level. However, at 50 ms, both the first pixel and the second pixel vary from the target grayscale value. More specifically, as described by the first difference curve  90 , even though the first pixel is written before the intra-frame pause  86 , the grayscale value of the first pixel still varies slightly from the target grayscale value. In some embodiments, the difference may result from the less than instantaneous switching of the TFT  48  in the first pixel and/or that the first pixel is not in the first row of display pixels  42 . Nonetheless, the difference in grayscale value of the first pixel will generally not be perceivable by a user&#39;s eyes since it varies by less than 0.1% from the target grayscale value. 
     On the other hand, as described by the second difference curve  92 , the intra-frame pause  86  causes the grayscale value of the second pixel to vary from the target grayscale value by approximately 1.2%. In other words, the second pixel may be more than 1.1% darker than the first pixel, which may be perceivable by a user&#39;s eyes. Furthermore, since the grayscale value of the second pixel does not catch up to the grayscale value of the first pixel until the grayscale values stop substantially changing (e.g., at 100 ms), the intra-frame pause  86  may cause a perceivable artifact at the second pixel from 50 ms until close to 100 ms. 
     As discussed above, a visual artifact may be perceivable when an intra-frame pause causes the perceived brightness level of a pixel after the intra-frame pause (e.g., the second pixel) to vary from the desired brightness level by a perceivable amount. For example, when the desired brightness level of the second pixel increases between successive image frames, a visual artifact may be perceivable because the second pixel appears darker than desired. On the other hand, when the desired brightness level of the second pixel decreases between successive image frames, a visual artifact may be perceivable because the second pixel appears brighter than desired. 
     Accordingly, the image data written to a pixel after an intra-frame pause (e.g., the second pixel) may be adjusted (e.g., over-driven or under-driven) to reduce the likelihood of a visual artifact being perceived. To help illustrate, the above example is continued in  FIG. 10A . More specifically,  FIG. 10A  is a plot that describes the grayscale value of the first pixel with the first grayscale curve  82  and the adjusted grayscale value of the second pixel with a third grayscale curve  94  over a period of operation between 0 to 150 ms, in which time is shown on the X-axis and relative grayscale value is shown on the Y-axis. 
     As in  FIG. 9A , the image frames displayed from 0 to 50 ms have a brightness level of 5% (e.g., grayscale value of 64). Additionally, at 50 ms, the desired brightness level of the image frame is increased from the previously displayed image frames. Thus, as described by the first grayscale curve  82 , the grayscale value of the image data written to the first pixel begins to be increased at 50 ms or very shortly thereafter. 
     On the other hand, as described by the second grayscale curve  84 , the grayscale value written to the second pixel begins to increase after the intra-frame pause  86 . More specifically, image data received from the image source  18  is adjusted so that the grayscale value written to the second pixel increases at a faster rate. In fact, at 75 ms, the grayscale value of the second pixel is higher than the grayscale value of the first pixel. In this manner, a user&#39;s eyes may be unable to perceive a brightness difference between the first pixel and the second pixel. More specifically, the user&#39;s eyes generally average the brightness level of a pixel over a short duration of time (e.g., 25 ms). In other words, since the average brightness level of the first pixel and the second pixel between 50 to 75 ms is substantially the same, the user&#39;s eyes may perceive the first pixel and the second pixel as having the same brightness level. 
     To more clearly illustrate, the portion of the plot between 50 to 75 ms is shown in more detail in  FIG. 10B . More specifically,  FIG. 10B  describes the first grayscale curve  82 , the second grayscale curve  84  (e.g., uncompensated), and the third grayscale curve  94  (compensated). As described above, the grayscale value of the second pixel is increased after the intra-frame pause  86 . Accordingly, as depicted, the second grayscale curve  84  and the third grayscale curve  94  begin to increase after the intra-frame pause  86 . However, the third grayscale curve  94  increases at a faster rate than the second grayscale curve  84 , which may reduce the likelihood of a perceivable artifact. 
     To help illustrate,  FIG. 10B  also describes the difference between the first grayscale curve  82  and the second grayscale curve  84  with a third difference curve  96  and the difference between the first grayscale curve  82  and the third grayscale curve  94  with a fourth difference curve  98 . As described by the third difference curve  96 , the intra-frame pause  86  may cause the brightness level of the first pixel to be higher (e.g., brighter) than the brightness level of the second pixel for substantially the entire duration between 50 to 75 ms when the second pixel is uncompensated. 
     On the other hand, as described by the fourth difference curve  98 , the intra-frame pause  86  causes the brightness level of the first pixel to initially be higher (e.g., brighter) than the brightness level of the second pixel. However, since the grayscale value of the image data written to the second pixel is increased at a faster rate than the image data written to the first pixel, the brightness level of the second pixel surpasses the brightness level of the first pixel. For example, in the depicted embodiment, the brightness level of the second pixel may be lower (e.g., darker) than the first pixel from 50 to 62 ms and higher (e.g., brighter) than the first pixel from 62 to 75 ms. In this manner, the user&#39;s eyes may average the brightness level of the second pixel across 50 to 75 ms and perceive the brightness level of the second pixel as undistinguishable from the brightness level of the first pixel. As such, the likelihood of the intra-frame pause  86  causing a perceivable visual artifact is minimized. 
     As described above, the likelihood of visual artifact being perceived increases as the difference between the desired brightness level of successively displayed image frames increases. More specifically, it may be determined that when the desired brightness level changes by more than a threshold amount a visual artifact will likely be perceived. To help illustrate, a block diagram of logic that may be used to compensate for an intra-frame pause at a display pixel written after the intra-frame pause is described in  FIG. 11 . 
     As depicted, a target grayscale value  100  and a displayed grayscale value  102  are input to a grayscale adjustment look-up table (LUT)  104  and a comparator  106 . More specifically, the display  12  may successively display a previous image frame and a current image frame. Thus, the displayed grayscale value  102  may describe the grayscale value written to the display pixel that enables the previous image frame to be displayed as desired. Additionally, the target grayscale value  100  may describe the grayscale value of image data corresponding with the current image frame received from an image source. More specifically, when the target grayscale value  100  is written to the display pixel without an intra-frame pause, the display pixel  42  illuminates at the desired brightness level. In other words, the target grayscale value  100  may indicate the desired brightness level of the display pixel  42  when the current image frame is displayed. 
     However, as described above, an intra-frame pause may cause a perceivable visual artifact at the display pixel. As such, the receive grayscale value  100  may be adjusted to compensate for the intra-frame pause. Accordingly, the comparator  106  may determine the amount the grayscale value of the display pixel is expected to change from the previous image frame to the current image frame by determining the difference between the target grayscale value  100  and the displayed grayscale value  102 . 
     As described above, when the grayscale value of the display pixel is expected to change above a threshold amount, a visual artifact may be perceivable. Accordingly, when the comparator  106  determines that the threshold  108  is exceeded, the grayscale adjustment look-up table  104  may be enabled. In some embodiments, the threshold amount may be determined based on the number of intra-frame pauses, frequency image frames are displayed, number of display pixels  42  in the display  12 , length of an intra-frame pause, or any combination thereof. Additionally, in some embodiments, the threshold amount may be predetermined and stored in memory  80 . 
     When enabled, the grayscale adjustment look-up table  104  may output an adjusted grayscale value  110  to compensate for the intra-frame pause. For example, when the grayscale value is expected to decrease by more than the threshold amount  108 , the grayscale adjustment look-up table  104  may output an adjusted grayscale value  110  less (e.g., darker) than the target grayscale value  100 . On the other hand, when the grayscale value is expected to increase by more than the threshold amount  108 , the grayscale look-up table  104  may output an adjusted grayscale value  110  higher (e.g., brighter) than the target grayscale value  100 . 
     Generally, the grayscale adjustment look-up table  104  may determine the adjusted grayscale value  110  based at least on the target grayscale value  100  and the displayed grayscale value  102 . For example, the grayscale adjustment look-up table  104  may map the target grayscale value  100  to the adjusted grayscale  110  value based on the difference between the displayed grayscale value  102  and the target grayscale value  100  (e.g., expected grayscale value change). For example, when the difference is larger, the grayscale adjustment look-up table  104  may increase the adjusted grayscale value  110  at a faster rate. Additionally, in some embodiments, the grayscale adjustment look-up table  104  may be predetermined based on various factors, such as number/size of the display pixels  42 , properties of a user&#39;s eyes (e.g., image perception ability), size of the electronic display  12 , and the like, and stored in memory  80 . 
     On the other hand, when the comparator  106  determines that the threshold is not exceeded, a visual artifact is not likely to be perceivable. As such, the grayscale adjustment look-up table  104  may be disabled and the target grayscale value  100  may be written to the display pixel. In this manner, the likelihood of a perceivable artifact at the display pixel written after the intra-frame pause is reduced. 
     As can be appreciated, an intra-frame pause may cause a delay in writing image data to each display pixel written after the intra-frame pause. As such, the grayscale value written to any of the display pixels after the intra-frame pause may be adjusted. One embodiment of a process  112  that may be used to compensate for an intra-frame pause is described in  FIG. 12 . Generally, the process  112  includes displaying a previous image frame and a portion of a current image frame (process block  113 ), detecting an intra-frame pause (process block  114 ), determining displayed grayscale value of the previous image frame (process block  116 ), determining target grayscale value the current image frame (process block  118 ), determining whether the difference between the displayed grayscale value and the target grayscale value is greater than a threshold (decision block  120 ), and displaying the current image frame (process block  122 ). Additionally, when the difference is greater than the threshold, the process  112  includes adjusting the grayscale value of the current image frame before the current image frame is displayed (process block  124 ). In some embodiments, one or more steps process  112  may be implemented with instructions stored in a tangible non-transitory computer readable medium, such as memory  80 , and executed by one or more processing units, such as processor  78 . 
     Accordingly, the timing controller  76  may instruct the display components  38  to display a previous image frame and a portion of a current image frame (process block  113 ). More specifically, the timing controller  76  may instruct the display components  38  to write a first set of grayscale values to one or more rows of the electronic display to display the previous image frame. After the previous image frame is displayed, the timing controller  76  may instruct the display components  38  to write a second set of grayscale values to one or more rows to display a portion of the current image frame. 
     During the writing of the current image frame, the timing controller  76  may determine when an intra-frame pause occurs (process block  114 ). Generally, intra-frame pauses may occur at fixed intervals, which may be stored in memory  80 . As such, the timing controller  76  may determine the fixed interval from memory  80  and implement the intra-frame pauses. More specifically, the timing controller  76  may instruct the display components  38  to pause writing the current image frame to the display pixels  42  and instruct the touch sensing components  40  to check for a user touch. 
     Additionally, during the intra-frame pause, the timing controller  76  may determine the displayed grayscale values (e.g., first set of grayscale values)  102  of the previous image frame (process block  116 ). In some embodiments, the image data written to the display pixels  42  is stored in a buffer, which may be included in memory  80 . Accordingly, the timing controller  76  may retrieve the corresponding image data from memory  80  to determine the first set of grayscale values (e.g., displayed grayscale value  102 ) written to the display pixels  42  to display the previous image frame. More specifically, the timing controller  76  may determine the displayed grayscale value  102  for at least the display pixels  42  still displaying the previous image frame. 
     Furthermore, during the intra-frame pause, the timing controller  76  may determine the target grayscale value  100  of a current image frame (process block  118 ). More specifically, the target grayscale value  100  may be received with image data from the image source (e.g., processor  18 ). In some embodiments, the image data received from the image source may be stored in a buffer, which may be included in memory  80 . Accordingly, the timing controller  76  may retrieve the corresponding image data from memory  80  to determine the target grayscale value  100  of the current image frame. 
     Additionally, as described above, a portion of the current image frame may be displayed before the intra-frame pause and a portion of the current image frame may be displayed after the intra-frame pause. As such, the timing controller  76  may determine the target grayscale value  100  (e.g., a fourth set of grayscale values) for at least the display pixels written after the intra-frame pause. 
     The timing controller  76  may then compare the displayed grayscale values of the previous image frame to the target grayscale value of the current image frame (decision block  120 ), for example, using the comparator  106 . More specifically, the timing controller  76  may determine whether grayscale value for each display pixel written after the intra-frame pause is expected to change by more than a threshold amount (e.g., difference between displayed grayscale value  102  to the target grayscale value  100 ). In other words, the timing controller  76  may determine whether a perceivable visual artifact is likely displayed at each pixel written after the intra-frame pause. 
     The timing controller  76  may then instruct the display components  38  to write a portion of the current image frame to the display pixels (process block  122 ). More specifically, when the grayscale value is not expected to change by more than the threshold amount, the timing controller  76  may instruct the display components  38  to display a portion of current image frame by writing the image data received from the image source to the display pixels  42  without substantial adjustment. In other words, the target grayscale value  100  may be written to the display pixels  42  to display the current image frame as desired. 
     On the other hand, when the grayscale value is expected to change by more than the threshold amount, the timing controller  76  may determine an adjusted grayscale value (e.g., a third set of grayscale values)  110  before instructing the display components  38  to display the portion of the current image frame. In some embodiments, the timing controller  76  may utilize the grayscale adjustment look-up table  104  to map the target grayscale value  100  to the adjusted grayscale value  110 . In other embodiments, the timing controller  76  may use algorithms to calculate the adjusted grayscale value  110 . Additionally, once the grayscale value of the image data is adjusted, the image data may be stored in the buffer to enable the timing controller  76  to determine whether a perceivable artifact may be displayed in a next successive image frame. In other words, the grayscale value (e.g., target grayscale value  100  or adjusted grayscale value  110 ) written to the display pixel to display the current image frame may be used as the displayed grayscale value  102  to determine whether a perceivable artifact is likely when the next successive image frame is displayed. 
     In this manner, the likelihood of an intra-frame pause causing a perceivable visual artifact is minimized. More specifically, as described above, the likelihood of perceivable visual artifacts may be minimized by over-driving (e.g., increasing) the grayscale value when the desired brightness level of successively display image frames is increasing by more than a threshold amount. 
     To help illustrate, two successively displayed image frames that can be displayed on the electronic display  12  are described in  FIGS. 13A-13C . More specifically,  FIGS. 13A-13C  describe a first image frame  128  and a second image frame  130  displayed immediately after the first image frame  128 . 
       FIG. 13A  describes the desired brightness level (e.g., target grayscale value) of the first image frame  126 A and the second image frame  128 A. In other words, the image frames  126 A and  128 A may be displayed when image data received from image source is written to the display pixels  42  without the use of an intra-frame pause. Additionally, as depicted, the desired brightness level increases from the first image frame  128 A to the second image frame  130 A. In other words, the electronic display  12  is successively displaying image frames with increasing brightness levels. 
       FIG. 13B  describes the grayscale value written to the display pixels  42  to achieve the desired brightness levels when an intra-frame pause  134  is used. In other words, a first portion  136  of the image frames  128 B and  130 B are displayed before the intra-frame pause  134  and a second portion  138  of the image frames  128 B and  130 B are displayed after the intra-frame pause  134 . 
     However, as described above, when the image data received from the image source is displayed with the use of an intra-frame pause, visual artifacts may be perceivable, particularly when the grayscale value of a display pixel is expected to change by more than a threshold amount. For the purpose of illustration, we assume that the grayscale value for each of the display pixels in the second portion  138  is expected to change by more than the threshold amount between the first image frame  128 B and the second image frame  130 B. Accordingly, as depicted, the grayscale value written to the display pixels in the second portion  138  of the second image frame  130 B are over-driven (e.g., increased). 
     It is noted that the second image frame  130 B is merely one instant in time, for example, immediately before a next image frame is displayed. As described above, the grayscale value of the display pixels may be over-driven by increasing the grayscale value at a faster rate. In other words, the grayscale value written to display the second image  130 B may be changing. For example, the grayscale value of the first portion  136  may initially be higher (e.g., brighter) than the grayscale value of the second portion  138  due to the intra-frame pause  134 . However, since increased at a faster rate, the grayscale value of the second portion  138  may surpass the grayscale value of the first portion  140 . In this manner, the user&#39;s eyes may average the changing grayscale value of the second portion  138  and perceive the second image frame  130 B at the desired brightness level. 
     In other embodiments, it may be possible to minimize the perceivability of visual artifacts. For example, instead of compensating each display pixel after the intra-frame pause  134 , only a transition portion may be compensated. For example,  FIG. 13C  describes the grayscale value written to the display pixels  42  to reduce the perceivability of visual artifacts. As in  FIG. 13B , a first portion  136  of the image frames  128 B and  130 B are displayed before the intra-frame pause  134  and a second portion  138  of the image frames  128 B and  130 B are displayed after the intra-frame pause  134 . 
     As depicted, only a transition portion  140  of the grayscale values of the display pixels after the intra-frame pause  134  (e.g., 40 rows of display pixels) are compensated. More specifically, the grayscale values written to the transition portion  140  may be adjusted to generate a gradient. In other words, the display pixels closer to the intra-frame pause  134  may be over-driven more than display pixels further from the intra-frame pause  134 . 
     In this manner, the user&#39;s eyes may average the grayscale values written to the transition portion  140  so that a smooth brightness transition is formed between the first portion  136  and the second portion  138  of the second image frame  130 C. In other words, the brightness level of the second image frame  130 C may not exactly match the desired brightness level. Nevertheless, the perceivability of the brightness variation may be reduced by smoothly transitioning from perceived brightness level of the first portion  136  to the perceived brightness level of the second portion  138 . In fact, using a gradient may enable the size of the buffer to be reduced since the buffer may store only image data corresponding with the transition portion  140  instead of the image data corresponding with entire the second portion  138  or the image data corresponding with the entire second image frame  130 . 
     Additionally, as described above, the likelihood of perceivable visual artifacts may be reduced by under-driving (e.g., decreasing) the grayscale value when the desired brightness level of successively display image frames is decreasing by more than a threshold amount. To help illustrate, two successively displayed image frames that can be displayed on the electronic display  12  are described in  FIGS. 14A-14C . More specifically,  FIGS. 14A-14C  describe a first image frame  142  and a second image frame  144  displayed immediately after the first image frame  142 . 
       FIG. 14A  describes the desired brightness level (e.g., target grayscale value) of the first image frame  142 A and the second image frame  144 A. In other words, the image frames  142 A and  144 A may be displayed when image data received from image source is written to the display pixels  42  without the use of an intra-frame pause. Additionally, as depicted, the desired brightness level decreases from the first image frame  142 A to the second image frame  144 A. In other words, the electronic display  12  is successively displaying image frames with decreasing brightness levels. 
       FIG. 14B  describes the grayscale value written to the display pixels  42  to achieve the desired brightness levels when an intra-frame pause  146  is used. In other words, a first portion  148  of the image frames  142 B and  144 B are displayed before the intra-frame pause  146  and a second portion  150  of the image frames  142 B and  144 B are displayed after the intra-frame pause  146 . For the purpose of illustration, we assume that the grayscale value for each of the pixels in the second portion  150  is expected to change by more than the threshold amount between the first image frame  142 B and the second image frame  144 B. Accordingly, as depicted, the grayscale values written to the display pixels in the second portion  138  of the second image frame  130 B are under-driven (e.g., decreased). 
     It is noted that the second image frame  144 B is merely one instant in time. As described above, the grayscale value of the display pixels may be under-drive by decreasing the grayscale value at a faster rate. For example, the grayscale value of the first portion  148  may initially be higher (e.g., brighter) than the grayscale value of the second portion  150  due to the intra-frame pause  146 . However, since decreased at a faster rate, the grayscale value of the second portion  150  may decrease below the grayscale value of the first portion  148 . In this manner, the user&#39;s eyes may average the changing grayscale value of the second portion  150  and perceive the second image frame  144 B at the desired brightness level. 
     In other embodiments, it may be possible to reduce the perceivability of visual artifacts by using a transition portion  152  between the first portion  148  and the second portion  150  as described in  FIG. 14C . As depicted, the display pixels closer to the intra-frame pause  146  may be under-driven more than display pixels further from the intra-frame pause  146 . In this manner, the user&#39;s eyes may average the grayscale values written to the transition portion  152  so that a smooth brightness transition is formed between the first portion  148  and the second portion  150  of the second image frame  144 C. 
     As such, the brightness level of the second image frame  144 C may not exactly match the desired brightness level. Nevertheless, the perceivability of the brightness variation may be reduced by smoothly transitioning from perceived brightness level of the first portion  148  to the perceived brightness level of the second portion  150 . In fact, using a gradient transition portion  152  may enable the size of the buffer to be reduced since the buffer may store only image data corresponding with the transition portion  152  instead of the image data corresponding with entire the second portion  150  or the image data corresponding with the entire second image frame  144 . 
     Accordingly, the technical effects of the present disclosure include improving user touch detection accuracy in an electronic display through the use of intra-frame pauses without generating perceivable visual artifacts. More specifically, the electronic display may use intra-frame pauses to check for a user touch at a higher frequency. Additionally, the likelihood of the intra-frame pause causing perceivable visual artifacts may be reduced by adjusting (e.g., over-driving or under-driving) the grayscale valued written to the display pixels. In this manner, a user&#39;s eyes may average out the brightness level of the display pixels so that the perceived brightness level is as desired. 
     The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.

Metadata:
Filing Date: 20150224
Publication Date: 20170131
Grant Date: 20170131
Priority Date: 20150224
Inventors: WANG CHAOHAO
SACCHETTO PAOLO
GE ZHIBING
CHEN CHENG
JIANG SHIH-CHYUAN FAN
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G3/2011", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2310/027", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0412", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/0266", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0271", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G5/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3648", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/04184", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0412", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2340/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04166", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/103", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2340/16", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0271", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0412", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2310/027", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0266", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/2011", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0446", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G5/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0266", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3648", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/103", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 56693198