PATENT DOCUMENT

Publication Number: US-10453432-B2
Application Number: US-201715699460-A
Country: US
Kind Code: B2

Title: Display adjustment

Abstract:
An electronic device includes an electronic display, whereby the electronic display includes an active area that includes a pixel having a display behavior that varies with temperature. The electronic display also includes processing circuitry. The processing circuitry may, when in operation, generate image data to send to the pixel and adjust the image data to generate corrected image data based at least in part on a stored correction value for the pixel, wherein the stored correction value corresponds to an effect of temperature on the pixel.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 an electronic display comprising an active area comprising a pixel having a display behavior that varies with temperature; and 
 processing circuitry configured to:
 receive image data to send to the pixel; 
 adjust the image data to generate corrected image data based at least in part on a stored correction value for the pixel, wherein the stored correction value corresponds to an effect of measured temperature on the pixel; and 
 adjust the corrected image data to generate additional corrected image data based at least in part on a second correction value, wherein the processing circuitry is configured to generate the second correction value by:
 receiving an indication of a property of the pixel, wherein the property comprises a voltage or a current; 
 determining, using a correction curve associated with the pixel, a third correction value based at least in part on a difference between the indication of the property and a target indication of the property; 
 receiving a second indication of the property of the pixel; 
 updating the correction curve based at least in part on an offset between the first indication and the second indication to generate a panel curve associated with the pixel; and 
 generating the second correction value using the panel curve, wherein the second correction value comprises the third correction value and the offset. 
 
 
 
     
     
       2. The electronic device of  claim 1 , wherein the processing circuitry is configured to transmit the additional corrected image data to the electronic display. 
     
     
       3. The electronic device of  claim 2 , wherein the electronic display is configured to utilize the additional corrected image data to drive the pixel. 
     
     
       4. The electronic device of  claim 1 , wherein processing circuitry is configured to generate the stored correction value. 
     
     
       5. The electronic device of  claim 4 , wherein processing circuitry is configured to generate the stored correction value based on a sensed condition affecting the pixel. 
     
     
       6. The electronic device of  claim 5 , wherein the electronic display is configured to sense the sensed condition affecting the pixel. 
     
     
       7. The electronic device of  claim 6 , wherein the electronic display is configured to sense a temperature generated by a heat producing component of the electronic device as the sensed condition affecting the pixel. 
     
     
       8. The electronic device of  claim 4 , wherein processing circuitry is configured to generate the stored correction value based upon a sensed condition affecting both the pixel and at least one additional pixel adjacent to the pixel. 
     
     
       9. The electronic device of  claim 4 , wherein processing circuitry is configured to generate the stored correction value as a reduced resolution version of a generated correction value for the pixel. 
     
     
       10. The electronic device of  claim 9 , wherein the processing circuitry is configured to scale the stored correction value to generate a scaled correction value. 
     
     
       11. The electronic device of  claim 10 , wherein the processing circuitry is configured to convert the scaled correction value to generate compensation driving data. 
     
     
       12. The electronic device of  claim 11 , wherein the processing circuitry is configured to convert the scaled correction value via interpolation of the scaled correction value. 
     
     
       13. The electronic device of  claim 11 , wherein the processing circuitry is configured to convert the scaled correction value via extrapolation of the scaled correction value. 
     
     
       14. The electronic device of  claim 11 , wherein the processing circuitry is configured to adjust the image data to generate corrected image data by applying the compensation driving data to the image data. 
     
     
       15. An electronic device comprising:
 processing circuitry configured to:
 receive a signal representative of a condition affecting a pixel of the electronic device at a first time; 
 generate a correction value based on the signal; 
 alter a resolution of the correction value to generate a reduced size correction value; 
 store the reduced size correction value in a storage device; 
 receive an indication of a property of the pixel, wherein the property comprises a voltage or a current; 
 determine, using a correction curve associated with the pixel, a correction value based at least in part on a difference between the indication of the property and a target indication of the property; 
 receive a second indication of the property of the pixel; 
 update the correction curve based at least in part on an offset between the first indication and the second indication to generate a panel curve associated with the pixel; and 
 generate a second correction value using the panel curve, wherein the second correction value comprises the correction value and the offset. 
 
 
     
     
       16. The electronic device of  claim 15 , wherein the processing circuitry is configured to receive an input value representative of a condition affecting the pixel of the electronic device at a second time. 
     
     
       17. The electronic device of  claim 16 , wherein the processing circuitry is configured to update the reduced size correction value based on the input value. 
     
     
       18. An electronic device comprising:
 an electronic display comprising an active area comprising a pixel; and 
 processing circuitry configured to:
 receive an indication of a property of the pixel, wherein the property comprises a voltage or a current; 
 determine, using a correction curve associated with the pixel, a correction value based at least in part on a difference between the indication of the property and a target indication of the property; 
 receive a second indication of the property of the pixel; 
 update the correction curve based at least in part on an offset between the first indication and the second indication to generate a panel curve associated with the pixel; 
 generate a second correction value using the panel curve, wherein the second correction value comprises the correction value and the offset; and 
 apply the second correction value to image data transmitted to the pixel. 
 
 
     
     
       19. The electronic device of  claim 18 , wherein the processing circuitry is configured to:
 receive a third indication of the property of the pixel; 
 update the panel curve based at least in part on an additional offset between the second indication and the third indication to generate an adapted panel curve associated with the pixel; and 
 generate a third correction value using the adapted panel curve, wherein the third correction value comprises the second correction value and the additional offset. 
 
     
     
       20. The electronic device of  claim 18 , wherein the processing circuitry is configured to update the correction curve to generate the panel curve associated with the pixel upon startup of the electronic device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Provisional Application Ser. No. 62/399,371, filed on Sep. 24, 2016 and entitled “Display Adjustment,” which is incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     The present disclosure relates to adjusting display of images on an electronic display based at least in part on sensed conditions affecting the electronic display. 
     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. 
     Numerous electronic devices—such as televisions, portable phones, computers, vehicle dashboards, and more—include electronic displays. As electronic displays gain increasing higher resolutions and dynamic ranges, they also may become more susceptible to environmental changes, such as changes in temperature. Thermal variations (as well as other factors) that affect an electronic display can cause different pixels to exhibit different display behaviors. Accordingly, these variations may induce an undesirable lack of uniformity across the display, which may be perceived as differences in color representation across one or more portions of the display and/or luminance differences of the display. 
     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. 
     Under certain conditions, non-uniformity of a display induced by process non-uniformity temperature gradients, or other factors across the display should be compensated for to increase performance of a display (e.g., reduce visible anomalies). The non-uniformity of pixels in a display may vary between devices of the same type (e.g., two similar phones, tablets, wearable devices, or the like), it can vary over time and usage (e.g., due to aging and/or degradation of the pixels or other components of the display), and/or it can vary with respect to temperatures, as well as in response to additional factors. 
     To avoid visual artifacts that could otherwise occur, techniques and systems outlined herein may be utilized in conjunction with an electronic display. In one example, an electronic device may store a prediction lookup table associated with independent heat-producing components of the electronic device that may create temperature variations on the electronic display. These heat-producing components could include, for example, a camera and its associated image signal processing (ISP) circuitry, wireless communication circuitry, data processing circuitry, and the like. Actual conditions of the electronic display may sensed and a correction lookup table may be established. Values from this lookup table may be added to image data to be displayed by the display as a correction factor to mitigate (e.g., compensate for) the impact of the sensed condition (e.g., thermal differences affecting the display). 
     Accordingly, this disclosure describes systems and techniques to provide an area based dynamic display uniformity correction that can be used to correct process, system, and/or environmental induced panel non-uniformities. This area based display uniformity correction can be applied at particular locations of the display or across the entirety of the display. In some embodiments, a lookup table of correction values may be a reduced resolution correction map to allow for reduced power consumption and increased response times. Additional techniques are disclosed to allow for dynamic and/or local adjustments of the resolution of the lookup table (e.g., a correction map), which also may be globally or locally updated based on real time measurements of the display, one or more system sensors, and/or virtual measurements of the display (e.g., estimates of temperatures affecting a display generated from measurements of power consumption, currents, voltages, or the like). 
     Additionally, per-pixel compensation may use large storage memory and computing power. Accordingly, reduced size representative values may be stored in a look-up table whereby the representative values subsequently may subsequently be decompressed, scaled, interpolated, or otherwise converted for application to input data of a pixel. Furthermore, the update rate for display image data and/or the lookup table may be variable or set at a preset rate. Dynamic reference voltages may also be applied to pixels of the display in conjunction with the corrective measures described above. 
     Additional compensation techniques related to adaptive correction of the display are also described. Pixel response (e.g., luminance and/or color) can vary due to component processing, temperature, usage, aging, and the like. In one embodiment, to compensate for non-uniform pixel response, a property of the pixel (e.g., a current or a voltage) may be measured and compared to a target value to generate correction value using estimated pixel response as a correction curve. However, mismatch between correction curve and actual pixel response due to panel variation, temperature, aging, and the like can cause correction error across the panel and can cause display artifacts, such as luminance disparities, color differences, flicker, and the like, to be present on the display. 
     Accordingly, pixel response to input values may be measured and checked for differences against a target response. Corrected input values may be transmitted to the pixel in response to any differences determined in the pixel response. The pixel response may be checked again and a second correction (e.g., an offset) may be additionally applied to insure that any residual errors are accounted for. The aforementioned correction values may supplement values transmitted to the pixel so that a target response of the pixel to an input is generated. This process may be done at an initial time (e.g., when the display is manufactured, when the device is powered on, etc.) and then repeated at one or more times to account for time-varying factors. In this manner, to accommodate for mismatches, a correction curve can be continuously monitored (or at predetermined intervals) in real time and adaptively adjusted on the fly to minimize correction error. 
     Various refinements of the features noted above may be made in relation to various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may be made individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. The brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of embodiments of the present disclosure without limitation to the claimed subject matter. 
    
    
     
       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 schematic block diagram of an electronic device that performs display sensing and compensation, in accordance with an embodiment; 
         FIG. 2  is a perspective view of a notebook computer representing an embodiment of the electronic device of  FIG. 1 ; 
         FIG. 3  is a front view of a hand-held device representing another embodiment of the electronic device of  FIG. 1 ; 
         FIG. 4  is a front view of another hand-held device representing another embodiment of the electronic device of  FIG. 1 ; 
         FIG. 5  is a front view of a desktop computer representing another embodiment of the electronic device of  FIG. 1 ; 
         FIG. 6  is a front view and side view of a wearable electronic device representing another embodiment of the electronic device of  FIG. 1 ; 
         FIG. 7  is a block diagram of an electronic display that performs display panel sensing, in accordance with an embodiment; 
         FIG. 8  is a thermal diagram indicating temperature variations due to heat sources on the electronic display, in accordance with an embodiment; 
         FIG. 9  is a block diagram of a process for compensating image data to account for changes sensed conditions affecting a pixel of the display of  FIG. 7 , in accordance with an embodiment; 
         FIG. 10  is a representation of converting the data values of a correction map of  FIG. 9 , in accordance with an embodiment; 
         FIG. 11  is a graphical example of updating of the correction map of  FIG. 9 , in accordance with an embodiment; 
         FIG. 12  is a diagram illustrating updating of voltage levels supplied to pixels of the display of  FIG. 7 , in accordance with an embodiment; 
         FIG. 13  is a graph illustrating a first embodiment of compensating for non-uniform pixel response of the display of  FIG. 7 , in accordance with an embodiment; 
         FIG. 14  is a graph illustrating a second embodiment of compensating for non-uniform pixel response of the display of  FIG. 7 , in accordance with an embodiment; and 
         FIG. 15  is a graph illustrating a third embodiment of compensating for non-uniform pixel response of the display of  FIG. 7 . 
     
    
    
     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. Furthermore, the phrase A “based on” B is intended to mean that A is at least partially based on B. Moreover, the term “or” is intended to be inclusive (e.g., logical OR) and not exclusive (e.g., logical XOR). In other words, the phrase A “or” B is intended to mean A, B, or both A and B. 
     Electronic displays are ubiquitous in modern electronic devices. As electronic displays gain ever-higher resolutions and dynamic range capabilities, image quality has increasingly grown in value. In general, electronic displays contain numerous picture elements, or “pixels,” that are programmed with image data. Each pixel emits a particular amount of light based on the image data. By programming different pixels with different image data, graphical content including images, videos, and text can be displayed. 
     As noted above, display panel sensing allows for operational properties of pixels of an electronic display to be identified to improve the performance of the electronic display. For example, variations in temperature and pixel aging (among other things) across the electronic display cause pixels in different locations on the display to behave differently. Indeed, the same image data programmed on different pixels of the display could appear to be different due to the variations in temperature and pixel aging. Without appropriate compensation, these variations could produce undesirable visual artifacts. Accordingly, the techniques and systems described below may be utilized to compensate for the operational variations across the display. 
     With this in mind, a block diagram of an electronic device  10  is shown in  FIG. 1 . As will be described in more detail below, the electronic device  10  may represent any suitable electronic device, such as a computer, a mobile phone, a portable media device, a tablet, a television, a virtual-reality headset, a vehicle dashboard, or the like. The electronic device  10  may represent, for example, a notebook computer  10 A as depicted in  FIG. 2 , a handheld device  10 B as depicted in  FIG. 3 , a handheld device  10 C as depicted in  FIG. 4 , a desktop computer  10 D as depicted in  FIG. 5 , a wearable electronic device  10 E as depicted in  FIG. 6 , or a similar device. 
     The electronic device  10  shown in  FIG. 1  may include, for example, a processor core complex  12 , a local memory  14 , a main memory storage device  16 , an electronic display  18 , input structures  22 , an input/output (I/O) interface  24 , network interfaces  26 , and a power source  28 . The various functional blocks shown in  FIG. 1  may include hardware elements (including circuitry), software elements (including machine-executable instructions stored on a tangible, non-transitory medium, such as the local memory  14  or the main memory storage device  16 ) 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 electronic device  10 . Indeed, the various depicted components may be combined into fewer components or separated into additional components. For example, the local memory  14  and the main memory storage device  16  may be included in a single component. 
     The processor core complex  12  may carry out a variety of operations of the electronic device  10 , such as causing the electronic display  18  to perform display panel sensing and using the feedback to adjust image data for display on the electronic display  18 . The processor core complex  12  may include any suitable data processing circuitry to perform these operations, such as one or more microprocessors, one or more application specific processors (ASICs), or one or more programmable logic devices (PLDs). In some cases, the processor core complex  12  may execute programs or instructions (e.g., an operating system or application program) stored on a suitable article of manufacture, such as the local memory  14  and/or the main memory storage device  16 . In addition to instructions for the processor core complex  12 , the local memory  14  and/or the main memory storage device  16  may also store data to be processed by the processor core complex  12 . By way of example, the local memory  14  may include random access memory (RAM) and the main memory storage device  16  may include read only memory (ROM), rewritable non-volatile memory such as flash memory, hard drives, optical discs, or the like. 
     The electronic display  18  may display image frames, such as a graphical user interface (GUI) for an operating system or an application interface, still images, or video content. The processor core complex  12  may supply at least some of the image frames. The electronic display  18  may be a self-emissive display, such as an organic light emitting diodes (OLED) display, or may be a liquid crystal display (LCD) illuminated by a backlight. In some embodiments, the electronic display  18  may include a touch screen, which may allow users to interact with a user interface of the electronic device  10 . The electronic display  18  may employ display panel sensing to identify operational variations of the electronic display  18 . This may allow the processor core complex  12  to adjust image data that is sent to the electronic display  18  to compensate for these variations, thereby improving the quality of the image frames appearing on the electronic display  18 . 
     The input structures  22  of the electronic device  10  may enable a user to interact with the electronic device  10  (e.g., pressing a button to increase or decrease a volume level). The I/O interface  24  may enable electronic device  10  to interface with various other electronic devices, as may the network interface  26 . The network interface  26  may include, for example, interfaces for a personal area network (PAN), such as a Bluetooth network, for a local area network (LAN) or wireless local area network (WLAN), such as an 802.11x Wi-Fi network, and/or for a wide area network (WAN), such as a cellular network. The network interface  26  may also include interfaces for, for example, broadband fixed wireless access networks (WiMAX), mobile broadband Wireless networks (mobile WiMAX), asynchronous digital subscriber lines (e.g., ADSL, VDSL), digital video broadcasting-terrestrial (DVB-T) and its extension DVB Handheld (DVB-H), ultra wideband (UWB), alternating current (AC) power lines, and so forth. The power source  28  may include any suitable source of power, such as a rechargeable lithium polymer (Li-poly) battery and/or an alternating current (AC) power converter. 
     In certain embodiments, the electronic device  10  may take the form of a computer, a portable electronic device, a wearable electronic device, or other type of electronic device. Such computers may include computers that are generally portable (such as laptop, notebook, and tablet computers) as well as computers that are generally used in one place (such as conventional desktop computers, workstations and/or servers). In certain embodiments, the electronic device  10  in the form of a computer may be a model of a MacBook®, MacBook® Pro, MacBook Air®, iMac®, Mac® mini, or Mac Pro® available from Apple Inc. By way of example, the electronic device  10 , taking the form of a notebook computer  10 A, is illustrated in  FIG. 2  in accordance with one embodiment of the present disclosure. The depicted computer  10 A may include a housing or enclosure  36 , an electronic display  18 , input structures  22 , and ports of an I/O interface  24 . In one embodiment, the input structures  22  (such as a keyboard and/or touchpad) may be used to interact with the computer  10 A, such as to start, control, or operate a GUI or applications running on computer  10 A. For example, a keyboard and/or touchpad may allow a user to navigate a user interface or application interface displayed on the electronic display  18 . 
       FIG. 3  depicts a front view of a handheld device  10 B, which represents one embodiment of the electronic device  10 . The handheld device  10 B may represent, for example, a portable phone, a media player, a personal data organizer, a handheld game platform, or any combination of such devices. By way of example, the handheld device  10 B may be a model of an iPod® or iPhone® available from Apple Inc. of Cupertino, Calif. The handheld device  10 B may include an enclosure  36  to protect interior components from physical damage and to shield them from electromagnetic interference. The enclosure  36  may surround the electronic display  18 . The I/O interfaces  24  may open through the enclosure  36  and may include, for example, an I/O port for a hard wired connection for charging and/or content manipulation using a standard connector and protocol, such as the Lightning connector provided by Apple Inc., a universal service bus (USB), or other similar connector and protocol. 
     User input structures  22 , in combination with the electronic display  18 , may allow a user to control the handheld device  10 B. For example, the input structures  22  may activate or deactivate the handheld device  10 B, navigate user interface to a home screen, a user-configurable application screen, and/or activate a voice-recognition feature of the handheld device  10 B. Other input structures  22  may provide volume control, or may toggle between vibrate and ring modes. The input structures  22  may also include a microphone may obtain a user&#39;s voice for various voice-related features, and a speaker may enable audio playback and/or certain phone capabilities. The input structures  22  may also include a headphone input may provide a connection to external speakers and/or headphones. 
       FIG. 4  depicts a front view of another handheld device  10 C, which represents another embodiment of the electronic device  10 . The handheld device  10 C may represent, for example, a tablet computer or portable computing device. By way of example, the handheld device  10 C may be a tablet-sized embodiment of the electronic device  10 , which may be, for example, a model of an iPad® available from Apple Inc. of Cupertino, Calif. 
     Turning to  FIG. 5 , a computer  10 D may represent another embodiment of the electronic device  10  of  FIG. 1 . The computer  10 D may be any computer, such as a desktop computer, a server, or a notebook computer, but may also be a standalone media player or video gaming machine. By way of example, the computer  10 D may be an iMac®, a MacBook®, or other similar device by Apple Inc. It should be noted that the computer  10 D may also represent a personal computer (PC) by another manufacturer. A similar enclosure  36  may be provided to protect and enclose internal components of the computer  10 D such as the electronic display  18 . In certain embodiments, a user of the computer  10 D may interact with the computer  10 D using various peripheral input devices, such as input structures  22 A or  22 B (e.g., keyboard and mouse), which may connect to the computer  10 D. 
     Similarly,  FIG. 6  depicts a wearable electronic device  10 E representing another embodiment of the electronic device  10  of  FIG. 1  that may be configured to operate using the techniques described herein. By way of example, the wearable electronic device  10 E, which may include a wristband  43 , may be an Apple Watch® by Apple, Inc. However, in other embodiments, the wearable electronic device  10 E may include any wearable electronic device such as, for example, a wearable exercise monitoring device (e.g., pedometer, accelerometer, heart rate monitor), or other device by another manufacturer. The electronic display  18  of the wearable electronic device  10 E may include a touch screen display  18  (e.g., LCD, OLED display, active-matrix organic light emitting diode (AMOLED) display, and so forth), as well as input structures  22 , which may allow users to interact with a user interface of the wearable electronic device  10 E. 
     As shown in  FIG. 7 , in the various embodiments of the electronic device  10 , the processor core complex  12  may perform image data generation and processing  50  to generate image data  52  for display by the electronic display  18 . The image data generation and processing  50  of the processor core complex  12  is meant to represent the various circuitry and processing that may be employed by the core processor  12  to generate the image data  52  and control the electronic display  18 . Since this may include compensating the image data  52  based on manufacturing and/or operational variations of the electronic display  18 , the processor core complex  12  may provide sense control signals  54  to cause the electronic display  18  to perform display panel sensing to generate display sense feedback  56 . The display sense feedback  56  represents digital information relating to the operational variations of the electronic display  18 . The display sense feedback  56  may take any suitable form, and may be converted by the image data generation and processing  50  into a compensation value that, when applied to the image data  52 , appropriately compensates the image data  52  for the conditions of the electronic display  18 . This results in greater fidelity of the image data  52 , reducing or eliminating visual artifacts that would otherwise occur due to the operational variations of the electronic display  18 . 
     The electronic display  18  includes an active area  64  with an array of pixels  66 . The pixels  66  are schematically shown distributed substantially equally apart and of the same size, but in an actual implementation, pixels of different colors may have different spatial relationships to one another and may have different sizes. In one example, the pixels  66  may take a red-green-blue (RGB) format with red, green, and blue pixels, and in another example, the pixels  66  may take a red-green-blue-green (RGBG) format in a diamond pattern. The pixels  66  are controlled by a driver integrated circuit  68 , which may be a single module or may be made up of separate modules, such as a column driver integrated circuit  68 A and a row driver integrated circuit  68 B. The driver integrated circuit  68  (e.g.,  68 B) may send signals across gate lines  70  to cause a row of pixels  66  to become activated and programmable, at which point the driver integrated circuit  68  (e.g.,  68 A) may transmit image data signals across data lines  72  to program the pixels  66  to display a particular gray level (e.g., individual pixel brightness). By supplying different pixels  66  of different colors with image data to display different gray levels, full-color images may be programmed into the pixels  66 . The image data may be driven to an active row of pixel  66  via source drivers  74 , which are also sometimes referred to as column drivers. 
     As mentioned above, the pixels  66  may be arranged in any suitable layout with the pixels  66  having various colors and/or shapes. For example, the pixels  66  may appear in alternating red, green, and blue in some embodiments, but also may take other arrangements. The other arrangements may include, for example, a red-green-blue-white (RGBW) layout or a diamond pattern layout in which one column of pixels alternates between red and blue and an adjacent column of pixels are green. Regardless of the particular arrangement and layout of the pixels  66 , each pixel  66  may be sensitive to changes on the active area of  64  of the electronic display  18 , such as variations and temperature of the active area  64 , as well as the overall age of the pixel  66 . Indeed, when each pixel  66  is a light emitting diode (LED), it may gradually emit less light over time. This effect is referred to as aging, and takes place over a slower time period than the effect of temperature on the pixel  66  of the electronic display  18 . 
     Display panel sensing may be used to obtain the display sense feedback  56 , which may enable the processor core complex  12  to generate compensated image data  52  to negate the effects of temperature, aging, and other variations of the active area  64 . The driver integrated circuit  68  (e.g.,  68 A) may include a sensing analog front end (AFE)  76  to perform analog sensing of the response of pixels  66  to test data. The analog signal may be digitized by sensing analog-to-digital conversion circuitry (ADC)  78 . 
     For example, to perform display panel sensing, the electronic display  18  may program one of the pixels  66  with test data. The sensing analog front end  76  then senses a sense line  80  of connected to the pixel  66  that is being tested. Here, the data lines  72  are shown to act as extensions of the sense lines  80  of the electronic display  18 . In other embodiments, however, the display active area  64  may include other dedicated sense lines  80  or other lines of the display  18  may be used as sense lines  80  instead of the data lines  72 . Other pixels  66  that have not been programmed with test data may be sensed at the same time a pixel that has been programmed with test data. Indeed, by sensing a reference signal on a sense line  80  when a pixel on that sense line  80  has not been programmed with test data, a common-mode noise reference value may be obtained. This reference signal can be removed from the signal from the test pixel that has been programmed with test data to reduce or eliminate common mode noise. 
     The analog signal may be digitized by the sensing analog-to-digital conversion circuitry  78 . The sensing analog front end  76  and the sensing analog-to-digital conversion circuitry  78  may operate, in effect, as a single unit. The driver integrated circuit  68  (e.g.,  68 A) may also perform additional digital operations to generate the display feedback  56 , such as digital filtering, adding, or subtracting, to generate the display feedback  56 , or such processing may be performed by the processor core complex  12 . 
     In some embodiments, a variety of sources can produce heat that could cause a visual artifact to appear on the electronic display  18  if the image data  52  is not compensated for the thermal variations on the electronic display  18 . For example, as shown in a thermal diagram  90  of  FIG. 8 , the active area  64  of the electronic display  18  may be influenced by a number of different nearby heat sources. For example, the thermal map  90  illustrates the effect of at least one heat source that creates high local distribution of heat  92  on the active area  64 . The heat source(s) that generate the distribution of heat  92  may be any heat-producing electronic component, such as the processor core complex  12 , camera circuitry, or the like, that generate heat in a predictable pattern on the electronic display  18 . 
     As further illustrated in  FIG. 8 , the thermal diagram  90  may be divided into regions  92  of the display  18  that each include a set of pixels  66 . In this manner, groups of pixels  66  may be represented by the regions  92  such that attributes for a region  92  (e.g., temperatures affecting the region  92 ) may be attributed to a group of pixels  66  of that region  92 . As will be discussed in greater detail below, grouping sensed attributes or influences of pixels  66  into regions  92  may allow for reduced memory requirements and processing when correcting for non-uniformity of the display  18 .  FIG. 8  additionally, shows an example of a correction map  96  that may include correction values  98  that correspond to the regions  92 . For example, the correction values  98  may represent offsets or other values applied to image data being transmitted to the pixels  66  in a region  94  to correct, for example, for temperature differences at the display  18  or other characteristics affecting the uniformity of the display  18 . 
     As shown in  FIG. 9 , the effects of the variation and non-uniformity in the display  18  may be corrected using the image data generation and processing system  50  of the processor core complex  12 . For example, the correction map  96  (which may correspond to a look up table having a set of correction values  98  that correspond to the regions  92 ) may be present in storage (e.g., memory) in the image data generation and processing system  50 . This correction map  96  may, in some embodiments, correspond to the entire active area  64  of the display  18  or a sub-segment of the active area  64 . As previously discussed, to reduce the size of the memory to store the correction map  96  (or the data therein), the correction map  96  may include correction values  98  that correspond to the regions  92 . Additionally, in some embodiments, the correction map  96  may be a reduced resolution correction map that enables low power and fast response operations. For example, the image data generation and processing system  50  may reduce the resolution of the correction values  98  prior to their storage in memory so that less memory may be required, responses may be accelerated, and the like. Additionally, adjustment of the resolution of the correction map  96  may be dynamic and/or resolution of the correction map  96  may be locally adjusted (e.g., adjusted at particular locations corresponding to one or more regions  92 ). 
     The correction map  96  (or a portion thereof, for example, data corresponding to a particular region  92 ), may be read from the memory of the image data generation and processing system  50 . The correction map  96  (e.g., one or more correction values) may then (optionally) be scaled (represented by step  100 ), whereby the scaling corresponds to (e.g., offsets or is the inverse of) a resolution reduction that was applied to the correction map  96 . In some embodiments, whether this scaling is performed (and the level of scaling) may be based on one or more input signals  102  received as display settings and/or system information. 
     In step  104  conversion of the correction map  96  may be undertaken via interpolation (e.g., Gaussian, linear, cubic, or the like), extrapolation (e.g., linear, polynomial, or the like), or other conversion techniques being applied to the data of the correction map  96 . This may allow for accounting of, for example, boundary conditions of the correction map  96  and may yield compensation driving data that may be applied to raw display content  106  (e.g., image data) so as to generate compensated image data  52  that is transmitted to the pixels  66 . A visual example of this process of step  104  is illustrated in  FIG. 10 , which illustrates an example of converting the data values of correction map  96  into compensation driving data organized into a per pixel correction map  108  from the correction map  96 . 
     Returning to  FIG. 9 , in some embodiments, the correction map  96  may be updated, for example, based on the input values  110  generated from the display sense feedback  56 . This updating of the correction map  96  may be performed globally (e.g., affecting the entirety of the correction map  96 ) and/or locally (e.g., affecting less than the entirety of the correction map  96 ). The update may be based on real time measurements of the active area  64  of the electronic display  18 , transmitted as display sense feedback  56 . Additionally and/or alternatively, a variable update rate of correction can be chosen, e.g., by the image data generation and processing system  50 , based on conditions affecting the display  18  (e.g., display  18  usage, power level of the device, environmental conditions, or the like). 
       FIG. 11  illustrates a graphical example of updating of the correction map  96 . As shown in graph  112 , a new data value  114  may be generated based on the display sense feedback  56  during an update at time n (corresponding to, for example, a first frame refresh). Also illustrated in graph  112  is the current look up table values  116  corresponding to particular row (e.g., row one) and column (e.g., columns one-five) pixel  66  locations. As part of the update of the correction map  96 , as illustrated in graph  118 , the new data value  114  may be applied to current look up table values  116  associated with (e.g., proximate to) the new data value  114 . This results in shifting of the look up table values  116  corresponding to pixels  66  affected by the condition represented by the new data value  114  to generate corrected look up table values  120  (illustrated along with the former look up table values  116  that were adjusted). 
     As illustrated in graph  122 , which represents an update at time n+1 (corresponding to, for example, a second frame refresh). An additional new data value data value  124  may be generated based on the display sense feedback  56  during an update at time n+1. As part of the update of the correction map  96 , as illustrated in graph  118 , the new data value  124  may be applied to current look up table values  116  associated with (e.g., proximate to) the new data value  124 . This results in shifting of the look up table values  116  corresponding to pixels  66  affected by the condition represented by the new data value  124  to generate corrected look up table values  126  (illustrated along with the former look up table values  116  that were adjusted). The illustrated update process in  FIG. 11  may represent a spatial interpolation example. However, it is understood that additional and/or alternative updating techniques may be applied to update the correction map  96 . 
     In some embodiments, dynamic correction voltages may be provided to the pixels  66  singularly and/or globally.  FIG. 12  illustrates an example of dynamic updating of voltage levels supplied to the pixels  66  and/or the active area  64 . As illustrated in diagram  128 , the image data generation and processing system  50  may receive display sense feedback  56  from, for example, one or more sensors  130 . Also illustrated is a voltage change map  132  that may include updated voltage values generated by sensed conditions received from the one or more sensors  130 . In some embodiments, the voltage change map  132  may be the correction map  96  discussed above. 
     Some pixels  66  may use one terminal for image dependent voltage driving and a different terminal for global reference voltage driving. Accordingly, as illustrated in  FIG. 12 , common mode information (e.g., a correction map average of the overall voltage change map  132 ) can be used to update global driving voltage along reference voltage line  134 . In this manner, for example, pixels of an active area  64  may adjusted together instead of individually (although individual adjustment would still be available via, for example, data lines  72 ). 
     Other techniques for corrections of non-uniformity of a display are additionally contemplated. For example, as illustrated in graph  134  of  FIG. 13 , to compensate for non-uniform pixel response, a property of the pixel  66  (e.g., a current or a voltage) may be measured  136  and compared to a target value  138  to generate correction value  140  (e.g., an offset voltage) using an estimated pixel  66  response to generate a correction curve  142 . This correction curve  142  may be used (e.g., in conjunction with a lookup table), for example to apply the correction value  140  to raw display content  106  (e.g., image data) so as to generate compensated image data  52  that is transmitted to the respective pixel  66  (e.g., the correction curve  142  may be used to choose offset voltages to be applied to the raw display content  106  based on a target current to be achieved). This process may be performed prior to or subsequent to the corrections discussed in conjunction with  FIG. 9  (e.g., the corrected data generated based upon application of a particular value selected in conjunction with the correction curve  142  may be transmitted as the raw display content  106  of  FIG. 9  or the compensated image data  52  of  FIG. 9  may be corrected in conjunction with the correction curve  142  and subsequently transmitted to the pixel  66 ). However, mismatch between the correction curve  142  and actual pixel  66  response due to panel variation, temperature, aging, and the like can cause correction error across the active area  64  of pixels  66  and can cause display artifacts, such as luminance disparities, color differences, flicker, and the like, to be present on the display  18 . 
       FIG. 14  illustrates a graph  144  that represents one technique to correct the correction curve  142  (e.g., to correct time-invariant curve mismatch, such as process variation). As illustrated in  FIG. 14 , a property of the pixel  66  (e.g., a current or a voltage) may be measured  146  and compared to a target value  148  to generate correction value  150  (e.g., an offset voltage) using a given correction curve  142  associated with the pixel  66 . This correction value  150  may be applied to in a manner similar to that described above with respect to correction value  140 . 
     Additionally, the property of the pixel  66  (e.g., a current a voltage) may be measured  152  at a second time, yielding a second measurement  146  that allows for residual correction (e.g., curve offset  152 ) to be additionally applied with the correction value  150  to generate a panel curve  154  that may be utilized (e.g., in conjunction with a lookup table) to apply the combined value of the correction value  150  and the curve offset  152  to, for example, raw display content  106  (e.g., image data) so as to generate compensated image data  52  that is transmitted to the pixels  66  (e.g., the panel curve  154  may be used to choose offset voltages to be applied to the raw display content  106  based on a target current to be achieved). This process may be performed prior to or subsequent to the corrections discussed in conjunction with  FIG. 9  (e.g., the corrected data generated based upon application of a particular value selected in conjunction with the panel curve  154  may be transmitted as the raw display content  106  of  FIG. 9  or the compensated image data  52  of  FIG. 9  may be corrected in conjunction with the panel curve  154  and subsequently transmitted to the pixel  66 ). This process may be performed as an initial configuration of the device  10  (e.g., at the factory and/or during initial device  10  or display  18  testing) or may be dynamically performed (e.g., at predetermined intervals or in response to a condition, such as startup of the device). 
       FIG. 15  illustrates a graph  156  that represents a technique to correct the panel curve  154  (e.g., to correct time-variant curve mismatch caused by temperature, age, usage, or the like). As illustrated in  FIG. 15 , the panel curve  154  may be originally calculated (e.g., when the device  10  and/or display is first manufactured or tested) and stored. Likewise, the panel curve  154  may be calculated as described above with respect to  FIG. 14  iteratively, for example, upon a power cycle of the device  10 . Once the panel curve  154  is determined and the correction value  150  and the curve offset  152  are being applied to provide image data  52  (e.g., the panel curve  154  may be used to choose offset voltages to be applied to the raw display content  106  based on a target current to be achieved), an additional correction technique may be undertaken. 
     As illustrated in  FIG. 15 , a property of the pixel  66  (e.g., a current a voltage) may be measured  158  and compared to a target value  160  to generate correction value  162  (e.g., an offset voltage) that allows for further correction of the panel curve  154  correction values (e.g., the correction value  150  and the curve offset  152 ). This results in generation of an adapted panel curve  164  that may be utilized (e.g., in conjunction with a lookup table) to apply the combined value of the correction value  150 , the curve offset  152 , and the correction value  162  to, for example, raw display content  106  (e.g., image data) so as to generate compensated image data  52  that is transmitted to the pixels  66  (e.g., the adapted panel curve  164  may be used to choose offset voltages to be applied to the raw display content  106  based on a target current to be achieved). This process may be performed prior to or subsequent to the corrections discussed in conjunction with  FIG. 9  (e.g., the corrected data generated based upon application of a particular value selected in conjunction with the adapted panel curve  164  may be transmitted as the raw display content  106  of  FIG. 9  or the compensated image data  52  of  FIG. 9  may be corrected in conjunction with adapted panel curve  164  and subsequently transmitted to the pixel  66 ). 
     The aforementioned described process may be performed on the fly (e.g., the panel curve  154  and/or the adapted panel curve  164  can be continuously monitored in real time and/or in near real time and adaptively adjusted on the fly to minimize correction error). Likewise, this process may be performed at regular intervals (e.g., in connection to the refresh rate of the display  18 ) to allows for enhancement correction accuracy for pixel  66  response estimation. In other embodiments, for example, in order to enhance curve adaptation further such as slope, the above adaptation procedure can be performed in multiple different current levels. Furthermore, as each pixel  66  may have its own I-V curve, the above noted process may be done for each pixel  66  of the display. 
     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. 
     The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function] . . . ” or “step for [perform]ing [a function] . . . ”, it is intended that such elements are to be interpreted under 35 U.S.C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U.S.C. 112(f).

Metadata:
Filing Date: 20170908
Publication Date: 20191022
Grant Date: 20191022
Priority Date: 20160924
Inventors: LIN, HUNG SHENG
CHANG, SUN-IL
NHO, HYUNWOO
RYU, JIE WON
TAN, JUNHUA
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G2320/0242", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G5/373", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/041", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0233", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0295", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/2096", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/041", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0252", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G5/393", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G5/391", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/043", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0233", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2330/021", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0285", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0295", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/2096", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0242", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2330/021", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G5/373", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0285", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/041", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G5/393", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/043", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0252", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G5/391", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/0233", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/0285", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0295", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/20", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 61686423