PATENT DOCUMENT

Publication Number: US-11087710-B2
Application Number: US-201816147045-A
Country: US
Kind Code: B2

Title: Dynamic VCOM compensation

Abstract:
A display includes a plurality of pixels grouped into a plurality of lines of pixels. Each line of pixels of the plurality of lines comprises a group of pixels of the plurality of pixels that are coupled to a common scan line as well and that are coupled to different data lines to individually activate each pixel of the group of pixels. The display also includes a common voltage (VCOM) driving circuit configured to receive a waveform and drive the waveform to the display as a VCOM having a value tailored to an individually activated pixel of the group of pixels.

Claims:
What is claimed is: 
     
       1. A display, comprising:
 a plurality of pixels grouped into a plurality of lines of pixels, wherein each line of pixels of the plurality of lines of pixels comprises a group of pixels of the plurality of pixels coupled to a common scan line and coupled to different data lines to individually activate each pixel of the group of pixels; and 
 a common voltage (VCOM) driving circuit configured to receive at least a first waveform and a second waveform that are predetermined and to drive the first waveform and the second waveform to the display as respective VCOM values tailored to a first pixel and a second pixel of the group of pixels, wherein the first waveform is associated with the first pixel and the second waveform is associated with the second pixel, such that the VCOM driving circuit uses the respective VCOM values for the first pixel and the second pixel when each respective pixel is activated. 
 
     
     
       2. The display of  claim 1 , comprising a VCOM source coupled to the VCOM driving circuit, wherein the VCOM source is configured to generate the first waveform and the second waveform and transmit the first waveform and the second waveform to the VCOM driving circuit. 
     
     
       3. The display of  claim 2 , wherein the VCOM source is configured to receive an input pulse signal and determine the first waveform based upon the input pulse signal. 
     
     
       4. The display of  claim 3 , comprising a timing controller coupled to the VCOM source, wherein the timing controller is configured to generate and transmit the input pulse signal. 
     
     
       5. The display of  claim 3 , wherein the VCOM source is configured to determine the first waveform by retrieving a stored waveform that is selected based upon the input pulse signal. 
     
     
       6. The display of  claim 3 , wherein the VCOM source is configured to dynamically generate the first waveform based upon the input pulse signal. 
     
     
       7. The display of  claim 2 , wherein the VCOM source is configured to receive an input pulse signal and generate the first waveform based upon the input pulse signal. 
     
     
       8. The display of  claim 7 , comprising a timing controller coupled to the VCOM source, wherein the timing controller is configured to generate and transmit the input pulse signal as including waveform information related to the first waveform. 
     
     
       9. The display of  claim 1 , comprising a second VCOM driving circuit configured to receive a third waveform and a fourth waveform and drive the third waveform and the fourth waveform to the display in conjunction with the first waveform and the second waveform driven by the VCOM driving circuit as the respective VCOM values tailored to the first pixel and the second pixel of the group of pixels to generate a composite VCOM waveform tailored to the first pixel and the second pixel of the group of pixels. 
     
     
       10. The display of  claim 1 , comprising a second VCOM driving circuit configured to receive a third waveform and drive the third waveform to the display in conjunction with the first waveform driven by the VCOM driving circuit as the respective VCOM value tailored to the first pixel. 
     
     
       11. The display of  claim 10 , comprising a VCOM source coupled to each of the VCOM driving circuit and the second VCOM driving circuit, wherein the VCOM source is configured to generate the first waveform and transmit the first waveform to the VCOM driving circuit, wherein the VCOM source is configured to generate the third waveform and transmit the third waveform to the second VCOM driving circuit. 
     
     
       12. The display of  claim 11 , wherein the VCOM source is configured to generate the third waveform as having a same voltage level as the first waveform. 
     
     
       13. The display of  claim 1 , wherein the VCOM driving circuit is configured to drive the first waveform to at least two separate connection points of the display as the respective VCOM value tailored to the first pixel of the group of pixels. 
     
     
       14. An electronic display, comprising:
 a plurality of pixels; 
 a first common voltage (VCOM) driving circuit configured to:
 receive at least a first and a second waveform that are predetermined as respective VCOM values tailored to a first pixel and a second pixel of the plurality of pixels, such that the first VCOM driving circuit uses the respective VCOM values for the first pixel and the second pixel when each respective pixel is activated; 
 provide a first portion of a first common voltage to a common electrode of the first pixel based at least in part on the first waveform when the first pixel is activated; and 
 provide a first portion of a second common voltage to a common electrode of the second pixel based at least in part on the second waveform when the second pixel is activated; and 
 
 a second VCOM driving circuit configured to:
 provide a second portion of the first common voltage to the common electrode of the first pixel when the first pixel is activated; and 
 provide a second portion of the second common voltage to the common electrode of the second pixel when the second pixel is activated, wherein the first common voltage is selected to have a voltage level associated with the first pixel and the second common voltage is selected to have a voltage level associated with the second pixel. 
 
 
     
     
       15. The electronic display of  claim 14 , comprising a panel having at least a first and a second side, wherein the first VCOM driving circuit and the second VCOM driving circuit are coupled to the first side of the panel. 
     
     
       16. The electronic display of  claim 14 , comprising a panel having at least a first and a second side, wherein the first VCOM driving circuit is coupled to the first side of the panel and wherein the second VCOM driving circuit is coupled to the second side of the panel. 
     
     
       17. The electronic display of  claim 14 , wherein the first VCOM driving circuit is configured to provide the first portion of the first common voltage as having a first voltage value, wherein the second VCOM driving circuit is configured to provide the second portion of the first common voltage as having the first voltage value. 
     
     
       18. The electronic display of  claim 14 , comprising a timing controller configured to synchronize transmission of a scanning signal to the first pixel with the first VCOM driving circuit providing the first portion of the first common voltage to the common electrode of the first pixel and with the second VCOM driving circuit providing the second portion of the first common voltage to the common electrode of the first pixel of the plurality of pixels when the first pixel is activated. 
     
     
       19. A display, comprising:
 a timing controller configured to:
 generate a pulse scanning signal utilized to control timing of a scan of the display; 
 generate a first pulse signal that is synchronized with the pulse scanning signal to generate a first waveform that is predetermined and driven to the display as a first common voltage (VCOM) value tailored to a first pixel in conjunction with the scan of the display, wherein the first waveform is associated with the first pixel, such that the first VCOM value is driven to the first pixel when the first pixel is activated; and 
 generate a second pulse signal pulse signal that is synchronized with the pulse scanning signal to generate a second waveform that is predetermined and driven to the display as a second common voltage (VCOM) value tailored to a second pixel in conjunction with the scan of the display, wherein the second waveform is associated with the second pixel, such that the second VCOM value is driven to the second pixel when the second pixel is activated. 
 
 
     
     
       20. The display of  claim 19 , wherein the timing controller is configured to generate a third pulse signal that is synchronized with the pulse scanning signal to generate a third waveform driven to the display as a third VCOM value tailored to a third pixel of the display in conjunction with the scan of the display.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The application is a Non-Provisional application claiming priority to U.S. Provisional Patent Application No. 62/619,584, entitled “Dynamic VCOM Compensation,” filed Jan. 19, 2018, which is herein incorporated by reference. 
    
    
     BACKGROUND 
     The present disclosure relates generally to electronic devices and, more particularly, to reducing display artifacts, such as flicker, in displays of the electronic devices. 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, 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. 
     Displays, such as liquid crystal displays (LCDs), are commonly used as screens or displays for a wide variety of electronic devices, including consumer electronics such as televisions, computers, and handheld devices (e.g., cellular telephones, audio and video players, gaming systems, and so forth). Such devices typically provide a flat display in a relatively thin package that is suitable for use in a variety of electronic goods. 
     LCD panels include a backlight and an array of pixels. The pixels contain liquid crystal material that can modulate the amount of light that passes from the backlight through the pixels. By causing different pixels to emit different amounts of light, the pixels may collectively display images on the display. Modulating the amount of light that passes through each pixel involves controlling electric fields applied to the liquid crystal material of each pixel. In particular, each pixel may have a pixel electrode that stores a data voltage. Groups of pixels may share a common electrode that provides a common voltage (VCOM) voltage. The voltage difference between the data voltage on the pixel electrode and the common voltage on the common electrode creates an electric field in each pixel. The electric field causes the liquid crystal material to modulate the amount of light. Indeed, the liquid crystal molecules in the liquid crystal material rotate in a way that causes a particular amount of light to pass through the pixel; this rotation depends on the magnitude of the electric field. That is, what matters is the magnitude of the voltage difference such that a positive voltage difference or a negative voltage difference of the same magnitude will generally cause the liquid crystal material to emit the same amount of light through the pixel. Thus, controlling the magnitude of the voltage difference between the pixel electrode and the common electrode controls the amount of light that passes through each pixel. 
     During operation, a display may experience kickback, which may be characterized as a reduction of the voltage (e.g., positive or negative) applied to the pixels in the display. As a display is typically driven alternatingly with positive and negative voltages, and since both the positive and negative voltages are moving toward negative (e.g., are being reduced via kickback), a center value of the positive and negative voltage will also be reduced. This may cause the common voltage (VCOM) to be different from the expected common voltage level (e.g., a desired VCOM level will be at the center value of the positive and negative voltages added to the pixel). Thus, the magnitude of the positive voltage with respect to VCOM and the magnitude of the negative voltage with respect to VCOM may be different. Since a display is typically driven by positive and negative voltages alternatively, this may cause the pixels of the display to emit light differently during positive and negative frames (e.g., when the positive and the negative voltages are applied), which can, therefore, produce visual artifacts, such as flicker, etc. that may be identifiable by a user. 
     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 relates to systems and methods of accounting for a voltage differences on a common electrode of a display. In particular, dynamic adjustment of a common voltage (VCOM) applied at pixels of the display to allow for compensation of, for example, non-uniformity across the display (e.g., across a panel of the display). VCOM non-uniformity may be caused by non-uniformity of an amount of kickback coupled to the pixel at different LCD locations, due to, for example, a lack of material and/or electrical uniformity in a display. Traditional direct current VCOM transmissions (e.g., transmission of one static VCOM level across a display) may lead to the generation of artifacts since, due to non-uniformity of the display, it may be difficult to generate and transmit a single VCOM level that matches a desired VCOM for each pixel of the display. Accordingly, in some embodiments, a VCOM may be generated and transmitted to the display whereby the VCOM is different at different location. Furthermore, the VCOM may be generated and transmitted as changing dynamically, for example, in conjunction with gate scanning of the display, so every pixel of the display may receive a compensated VCOM that approaches or is its desired Optimal VCOM. In this manner, kickback induced VCOM non-uniformity may be compensated for and the related visual artifacts may be minimized and/or eliminated, thus improving user experience. 
     In some embodiments, single or multiple drivers to vary the VCOM at a line-to-line basis to allow for driving of the VCOM to particular levels associated with the various lines of pixels. Furthermore, synchronizing the VCOM as a line-to-line adjustment to the panel gate scanning may allow only the active pixel to receive a locally compensated VCOM. In some embodiments, multiple driving points can be used anywhere on the panel to compensate complex non-uniformity profile. 
    
    
     
       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 an electronic device, 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 a portion of the display of  FIG. 1 , in accordance with an embodiment; 
         FIG. 8  is a block diagram of a portion of the display controller of  FIG. 7 , in accordance with an embodiment; 
         FIG. 9  is a block diagram of a portion of the display of  FIG. 1 , in accordance with an embodiment; 
         FIG. 10  illustrates a second block diagram of a portion of the display of  FIG. 1  and an associated first graph illustrating a one dimensional VCOM compensation being applied thereto, in accordance with an embodiment; 
         FIG. 11  illustrates a third block diagram of a portion of the display of  FIG. 1  and an associated second graph illustrating a two dimensional VCOM compensation being applied thereto, in accordance with an embodiment; 
         FIG. 12  is a fourth flock diagram of a portion of the display of  FIG. 1 , in accordance with an embodiment; 
         FIG. 13  is a fifth block diagram of a portion of the display of  FIG. 1 , in accordance with an embodiment; 
         FIG. 14  is a sixth block diagram of a portion of the display of  FIG. 1 , in accordance with an embodiment; 
         FIG. 15  is a seventh block diagram of a portion of the display of  FIG. 1 , in accordance with an embodiment; and 
         FIG. 16  is an eighth block diagram of a portion of the display of  FIG. 1 , in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are 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 would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     Present embodiments are generally directed to accounting for non-uniformities in a common voltage (VCOM) of a display. For example, dynamic adjustment of VCOM levels and reference points across partitions may be implemented to compensate for VCOM non-uniformities of a display. In one embodiment, dynamically adjusting the VCOM to compensate for VCOM non-uniformity across the whole panel may be accomplished through the use of single/multiple drivers to vary the VCOM on a line-to-line basis, thus allowing for driving of the VCOM to prescribed local values. Furthermore, a controller may operate to synchronize the VCOM line-to-line adjustment to the panel gate scanning, so that only a particular active pixel sees a local compensated VCOM value. In some embodiments, multiple driving points can be used anywhere on the panel to compensate complex non-uniformity profile. 
     Turning first to  FIG. 1 , an electronic device  10  according to an embodiment of the present disclosure may include, among other things, one or more processor(s)  12 , memory  14 , nonvolatile storage  16 , a display  18 , input structures  22 , an input/output (I/O) interface  24 , a network interface  26 , and a power source  28 . The various functional blocks shown in  FIG. 1  may include hardware elements (including circuitry), software elements (including computer code stored on a 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 electronic device  10 . 
     By way of example, the electronic device  10  may represent a block diagram of the notebook computer depicted in  FIG. 2 , the handheld device depicted in  FIG. 3 , the handheld device depicted in  FIG. 4 , the desktop computer depicted in  FIG. 5 , the wearable electronic device depicted in  FIG. 6 , or similar devices. It should be noted that the processor(s)  12  and other related items in  FIG. 1  may be generally referred to herein as “data processing circuitry.” Such data processing circuitry may be embodied wholly or in part as software, firmware, hardware, or any combination thereof. Furthermore, the data processing circuitry may be a single contained processing module or may be incorporated wholly or partially within any of the other elements within the electronic device  10 . 
     In the electronic device  10  of  FIG. 1 , the processor(s)  12  may be operably coupled with the memory  14  and the nonvolatile storage  16  to perform various algorithms. Such programs or instructions executed by the processor(s)  12  may be stored in any suitable article of manufacture that includes one or more tangible, computer-readable media at least collectively storing the instructions or routines, such as the memory  14  and the nonvolatile storage  16 . The memory  14  and the nonvolatile storage  16  may include any suitable articles of manufacture for storing data and executable instructions, such as random-access memory, read-only memory, rewritable flash memory, hard drives, and optical discs. In addition, programs (e.g., an operating system) encoded on such a computer program product may also include instructions that may be executed by the processor(s)  12  to enable the electronic device  10  to provide various functionalities. 
     In certain embodiments, the display  18  may be a liquid crystal display (LCD), which may allow users to view images generated on the electronic device  10 . In some embodiments, the display  18  may include a touch screen, which may allow users to interact with a user interface of the electronic device  10 . Furthermore, it should be appreciated that, in some embodiments, the display  18  may include one or more organic light emitting diode (OLED) displays, or some combination of LCD panels and OLED panels. 
     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, one or more 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 3rd generation (3G) cellular network, 4th generation (4G) cellular network, long term evolution (LTE) cellular network, a long term evolution license assisted access (LTE-LAA) cellular network, or the like. The network interface  26  may also include one or more 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. As further illustrated, the electronic device  10  may include a power source  28 . 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 computer  10 A, such as a notebook computer, 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 , a 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 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 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. 
     Input structures  22 , in combination with the 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 one of various portable computing devices. 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®, an iPad Pro®, or other similar device by 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 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 the keyboard  22 A or mouse  22 B (e.g., input structures  22 ), 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 display  18  of the wearable electronic device  10 E may include a touch screen display (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. 
     Turning now to  FIG. 7 , which generally represents a circuit diagram of certain components of the display  18  in accordance with some embodiments. In particular, a panel  44  of the display  18  (e.g., a display panel) may include a number of unit pixels  46  (e.g., pixels) disposed in a pixel array or matrix. In such an array, each unit pixel  46  may be defined by the intersection of rows and columns, represented by gate lines  48  (also referred to as scanning lines), and data lines  50 , respectively. Although only 6 unit pixels  46  are shown for purposes of simplicity, it should be understood that in an actual implementation, each gate line  48  and data line  50  may include hundreds or thousands of such unit pixels  46 . Each of the unit pixels  46  may represent one of three subpixels that respectively filters only one color (e.g., red, blue, or green) of light through, for example, a color filter. The terms “pixel,” “subpixel,” and “unit pixel” may be used largely interchangeably to refer to each individual picture element of the display  18 . However, the term “pixel” also sometimes refers to a collection of subpixels that can collectively display any suitable color (e.g., a pixel may be formed from a red subpixel, a green subpixel, and a blue subpixel; collectively, the pixel may be able to display any suitable color that can be formed by mixing red, green, and blue light). 
     As shown in  FIG. 7 , each unit pixel  46  may include a thin film transistor (TFT)  52  for switching a data signal stored on a respective pixel electrode  54 . However, it should be noted that the VCOM compensation for the display  18  as described herein is not limited to a display  18  using TFT technology, but may instead utilize, for example, another type of LCD display or an OLED display. Returning to  FIG. 7 , the potential stored on the pixel electrode  54  relative to a potential of a common electrode  56  (e.g., creating a liquid crystal capacitance CsT), which may be shared by other pixels  46 , may generate an electrical field sufficient to alter the arrangement of liquid crystal molecules of each unit pixel  46 . In the illustrated embodiment of  FIG. 7 , a source  58  of each TFT  52  may be electrically connected to a data line  50  and a gate  60  of each TFT  52  may be electrically connected to a gate line  48 . A drain  62  of each TFT  52  may be electrically connected to a respective pixel electrode  54 . Each TFT  52  may serve as a switching element that may be activated and deactivated (e.g., turned “ON” and turned “OFF”) for a predetermined period of time based on the respective presence or absence of a scanning signal on the gate lines  48  that are applied to the gates  60  of the TFTs  52 . 
     When activated, a TFT  52  may store the image signals received via the respective data line  50  as a charge upon the corresponding pixel electrode  54 . As noted above, the image signals stored by the pixel electrode  54  may be used to generate an electrical field between the respective pixel electrode  54  and a common electrode  56 . This electrical field may align the liquid crystal molecules to modulate light transmission through the pixel  46 . Furthermore, it should be appreciated that each unit pixel  46  may also include a storage capacitor, or circuitry that may be modeled as a capacitor, which may be used to sustain the pixel electrode voltage (e.g., V pixel ) during the time in which the TFTs  52  may be switch to the “OFF” state. 
     In certain embodiments, the display  18  also may include a display controller  64 , which may, for example, be an integrated circuit (IC), a chip, such as a processor or application specific integrated circuit (ASIC), or the like that receives image data from the processor(s)  12  and sends corresponding image signals to the a source driver  66  for transmission to unit pixels  46  of the panel  44  along columns of the pixels  46 . The display controller  64  may also provide timing signals to the gate drivers  68  and  70  to facilitate the activation/deactivation of individual rows of pixels  46 . 
     The display  18  may additionally include a common voltage (VCOM) source  72  to provide the common voltage (VCOM) to the common electrodes  56  of each of the pixels  46  via one or more VCOM drivers  84  (e.g., driving circuits or drivers). As illustrated, the display controller  64  may be coupled to the VCOM source  72  and may operate to control the VCOM source  72 , as will be described in greater detail below. 
       FIG. 8  illustrates the display controller  64  of  FIG. 7 . As illustrated, the display controller  64  may include, for example, a timing controller (TCON)  76  to facilitate controlling operation of the unit pixels  46  of the panel  44  and, in some embodiments, for example, the VCOM source  72 . As illustrated, the timing controller  76  may include a processor  78  and memory  80 . More specifically, the processor  78  may execute instructions stored in memory  80  to perform operations in the display  18 . 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 . The TCON  76  may also include VCOM compensation circuitry  82  that operates to generate signals for transmission to the VCOM source  72 . In some embodiments, the VCOM compensation circuitry  82  may operate as a controller used to generate pulse signals that are transmitted to the VCOM source  72  as input signals (e.g., input pulse signals) to allow the VCOM source  72  to generate and transmit waveforms (e.g., voltage levels) to drivers associated with the VCOM source  72  and the display  18 . The pulse signal(s) transmitted from the VCOM compensation circuitry  82  and/or the TCON  76  may be a synchronization signal that operates to set the start of a VCOM compensation, e.g., so that the TCON  76  controls synchronization of a VCOM compensation waveform generation and/or transmission (e.g., a waveform transmitted as an output from the VCOM source  72 ) with gate line-by-line scanning of the panel  44 . 
     In other embodiments, the VCOM compensation circuitry  82  may operate as a lookup table to be used by the processor  78  in determining and generating pulse signals that are transmitted to the VCOM source  72  as input signals to allow the VCOM source  72  to generate and transmit waveforms (e.g., voltage levels) to drivers associated with the VCOM source  72  and the display  18  which may be, for example, synchronized with gate line-by-line scanning operations. Additionally or alternatively to location within the TCON  76 , the VCOM compensation circuitry  82  may located within systems on chips (SoC) and/or column drivers of the electronic device  10 . Furthermore, in certain embodiments, VCOM compensation instructions may be stored in the memory  20  to be executed by the processor  12  to compensate for VCOM fluctuations. 
     As illustrated in  FIG. 9 , the display  18  may include the panel  44 , the VCOM source  72 , as well as one or more VCOM drivers  84  (e.g., driving circuits or drivers). The VCOM drivers  84  (e.g., the one or more VCOM drivers  84 ) may be buffers or amplifiers that operate to drive respective portions of the panel  44 . The panel  44  includes connection points  86  (e.g., inputs) on a first side  88  and on a second side  90  of the panel  44  that correspond to a vertical direction. Similarly, the panel  44  includes connection points  92  (e.g., inputs) on a third side  94  and on a fourth side  96  of the panel  44  that correspond to a horizontal direction. It should be noted that the example in  FIG. 9  is for illustrative purposes only and other panel  44  shapes (e.g., circular, triangular, pentagon, hexangular, etc) can be utilized in place of the illustrated panel  44 . Similarly, the one or more VCOM drivers  84  can be positioned at any location on and/or along any side of the panel  44  as illustrated or when having a different shape. 
     As illustrated, the VCOM drivers  84  have an output  98  that is coupled to the connection points  86  on the first side  88  of the panel  44  to drive waveforms (e.g., voltage signals) to the pixels  46 , as previously described with respect to  FIG. 7 . However, again, it should be noted that  FIG. 9  is for illustrative purposes and that the one or more VCOM drivers  84  can located anywhere on and/or along the panel  44  and, similarly, the output  98 , although illustrated as being coupled to the connection points  86  of the panel  44 , can also be disposed anywhere on and/or along the panel  44 . Indeed, VCOM drivers  84  and their corresponding output(s)  98  are not required to be disposed along a single edge of the panel  44  or at a common location of the panel  44 . 
     Likewise, the VCOM drivers  84  include an input  100  that receives waveform signals (e.g., voltage signals) from the VCOM source  72 . As illustrated, two VCOM drivers  84  are disposed on the first side  88  of the panel  44  to drive waveforms (e.g., voltage signals) to the pixels  46 , however, it may be appreciated that a single VCOM driver  84  may be employed or more than two VCOM drivers  84  may be utilized along the first side  88  of the panel  44  as well as in other locations along the panel  44 , as will be described below in greater detail. 
     In operation, the VCOM source  72  may dynamically adjust the VCOM transmitted via the VCOM drivers  84  to compensate for VCOM non-uniformity across the panel  44 . In some embodiments, the VCOM source  72  may generate one or more output waveforms (e.g., a voltage signal or voltage signals) that may be transmitted to the VCOM drivers  84  to be input into the panel  44  (e.g., to be provided as the VCOM to the common electrodes  56  of the pixels  46 ). The output waveform may be generated internally by the VCOM source  72  based upon a pulse signal transmitted from the TCON  76  (e.g., one or more pulse signals transmitted from the TCON  76  and/or the VCOM compensation circuitry  82 , as described above with respect to  FIG. 8 ). For example, a pulse signal may be received as an input signal at the VCOM source  72  and the VCOM source  72  may select a predetermined saved output waveform to output to the VCOM drivers  84  based upon the received pulse signal. Likewise, in some embodiments, the VCOM source  72  may include a processor and corresponding memory that operate to receive the pulse signal and generate (e.g., calculate or determine) an output waveform to output to the VCOM drivers  84  based upon the waveform pulse. Alternatively, the pulse signal may be generated via the TCON  76  (e.g., by or in conjunction with the VCOM compensation circuitry  82 ) and transmitted inclusive of waveform information itself (e.g., information related to, identifying, or otherwise indicative of the output waveform) as part of the pulse signal transmitted to the VCOM source  72  to be utilized in the generation of the waveform VCOM (e.g., output waveform) transmitted to the VCOM driver(s)  84 . Likewise, in some embodiments, one or more of these techniques may be utilized with the TCON  76  including the VCOM source  72  or performing the above noted functions of the VCOM source  72 . 
     In some embodiments, the output waveform (e.g., the common voltage) transmitted to the VCOM drivers  84  and, accordingly, the panel  44  and may be varied on a line-to-line basis (e.g., at groupings of pixels  46  grouped together in lines) to allow for driving of the VCOM to particular levels associated with the various lines of pixels  46  of the display  18  to provide local VCOM levels for pixels  46  of a line of the panel  44 . Likewise, the TCON  76  and/or the VCOM source  72  may operate to synchronize the VCOM line-to-line adjustment to the scanning signal transmitted to the gate lines  48  (e.g., the scanning lines), so that only the active pixel  46  of a line of pixels  46  receives the locally compensated VCOM. That is, the pixels  46  of a line may each receive the VCOM as in input, but only the pixel  46  of the line of pixels  46  that also receives a scanning signal with the VCOM allows causes activation of the pixel  46  and, accordingly, utilizes the VCOM. Furthermore, in some embodiments, the VCOM drivers  84  may operate cooperatively and/or simultaneously to generate a VCOM in conjunction with a gate scan (e.g., to dynamically change the VCOM in conjunction with the gate scanning of the panel  44 ). This process is further illustrated with respect to  FIGS. 10 and 11 . 
       FIG. 10  illustrates a panel  44  having a 1D (e.g., one dimensional) VCOM compensation (e.g., in a vertical direction) applied thereto, as further illustrated in graph  102 . Similarly,  FIG. 11  illustrates a panel  44  having a 2D (e.g., two dimensional) VCOM compensation (e.g., in a horizontal direction and in a vertical direction) applied thereto, as further illustrated in graph  104 . As illustrated in each of  FIGS. 10 and 11 , a panel  44  includes a representative first line  106  of pixels  46  being driven via a positive voltage value and a second line  108  of pixels  46  being driven via a negative voltage value during a scan  110  of the panel  44  whereby the voltage values, for example, have the same absolute value. However, as noted above, in  FIG. 10 , the panel  44  is illustrated as having a 1D VCOM compensation applied thereto. 
     Graph  102  of  FIG. 10  illustrates a waveform  112  may be applied to both of the drivers  84  of  FIG. 10  (e.g., the waveform  112  may represent a single waveform that is generated and transmitted to both of the drivers  84  having separate connection points  86 , for example, or the waveform  112  may represent separate waveforms having the same voltage level that are generated and transmitted to both of the drivers  84  having separate connection points  86 , for example). Additionally graph  102  illustrates a portion  114  of the scan  110  associated with the first line  106  of pixels  46  and a portion  116  of the scan  110  associated with the second line  108  of pixels  46 . Furthermore, no matter where the drivers  84  are positioned along panel  44  in  FIG. 10 , the driving signal (e.g., waveform  112  as the output waveform from VCOM source  72 ) applied to each of the drivers  84  provides for 1D VCOM compensation. The 1D VCOM compensation may, for example, be in a direction along a gate scan direction (e.g., illustrated by scan  110  as progressing downwards across the panel  44 ), so that if the panel  44  is scanning from top to bottom (or from bottom to top), vertical non-uniformity associated with the panel  44  may be compensated. Similarly, if the panel  44  scan  110  is from left to right (or from right to left) across the panel  44 , horizontal non-uniformity associated with the panel  44  may be compensated. 
     In  FIG. 11 , the panel  44  is illustrated as having a 2D VCOM compensation applied thereto. Graph  104  illustrates a waveform  118  that is applied to one of the drivers  84  of  FIG. 11  (e.g., the leftmost driver  84  of  FIG. 11 ). Likewise, graph  104  also illustrates a waveform  120  that is applied to the other one of the drivers  84  of  FIG. 11  (e.g., the rightmost driver  84  of  FIG. 11 ). Thus, as illustrated in  FIG. 11 , no matter where the drivers  84  are positioned along panel  44 , the driving signals (e.g., waveforms  118  and  120  as the output waveforms from VCOM source  72 ) provide 2D VCOM compensation through an integrated effect generated by the driving of different waveforms via the different drivers  84  at each time in the scan  110  to generate a composite VCOM waveform (e.g., a resultant VCOM based upon via the individually driven waveforms  118  and  120  as the VCOM applied to the panel  44 ). 
     In some embodiments, for 2D VCOM compression, the position of drivers  84  influences the VCOM compensation (e.g., the result of the 2D VCOM compression). For example, the drivers  84  work in conjunction during 2D VCOM compression, so their positioning will affect how the voltages from the different drivers  84  are integrated on the panel  44 . For example, if the driver  84  locations illustrated in  FIG. 11  were reversed while waveforms  118  and  120  remained the same, the resultant VCOM (e.g., the VCOM compensation) will be different (e.g., the bottom left portion of panel  44  would be negative while the top right portion of the panel  44  would be positive). 
       FIG. 10  and  FIG. 11  are intended to provide respective examples for 1D VCOM compensation and 2D VCOM compensation, respectively. However, dynamic VCOM compensation as described herein may be, for example, utilized to compensate for a number of types of for VCOM non-uniformities of the panel  44  (e.g., and is not limited to the panel  44  VCOM non-uniformity as illustrated in  FIG. 10  and  FIG. 11 ). Similarly, the compensation waveforms generated may be any number of types of waveforms generated for the compensation to be undertaken and are, for example, not limited to the waveforms  112 ,  118 , and  120  of  FIG. 10  and  FIG. 11 ). 
     Furthermore, with respect to VCOM 1D compensation, it is a common waveform (e.g., waveform  112  or another waveform) that is applied to one or more buffers  84  driving at one or more locations along or on the panel  44  to compensate for VCOM non-uniformity along the gate scanning direction. Likewise, for VCOM 2D compensation, there are two or more waveforms (e.g., waveforms  118  and  120  or other waveforms) that are applied to two or more buffers  84  driving at two or more locations along or on the panel  44  simultaneously to create an integrated effect to compensate for any arbitrary 2D VCOM non-uniformity of the panel  44 . 
     Returning to  FIG. 9 , the location of the illustrated VCOM drivers  84  on the first side  88  of the panel  44  is intended to be for illustrative purposes only. Indeed, it should be appreciated that multiple VCOM drivers  84  along connection points  86  and/or connection points  92  can be utilized anywhere on the outside region of the panel  44  (or in an internal region of the panel  44 ) to provide VCOM compensation.  FIGS. 12-16  provide examples of locating VCOM drivers  84  along differing portions of a panel  44  to allow for different VCOM compensation outputs to be utilized. 
     As illustrated in  FIG. 12 , the display  18  may include VCOM drivers  84  that may be coupled to the third side  94  of the panel  44  at two connection points  92  and VCOM drivers  84  may be coupled to the fourth side  96  of the panel  44  at two different connection points  92 . As illustrated, the VCOM driver  84  coupled to the third side  94  of the panel  44  receive an output waveform and the VCOM driver  84  coupled to the fourth side  96  of the panel  44  may receive an output waveform (which may be the same or different than the output waveform received by the VCOM driver  84  coupled to the third side  94  of the panel  44 ). In total, the VCOM drivers  84  will transmit the received output waveforms into the panel  44  (as illustrated, via separate connection points  92  on each of the third side  94  of the panel  44  and the fourth side  96  of the panel  44 ) resulting in an adjusted VCOM being supplied to the gate activated pixel  46  of a particular line of pixels  46 . 
       FIG. 13  illustrates the display  18  having two VCOM drivers  84  that may be coupled to the third side  94  of the panel  44  at two connection points  92  and two VCOM drivers  84  may be coupled to the fourth side  96  of the panel  44  at two different connection points  92 . The VCOM drivers  84  coupled to the third side  94  of the panel  44  may each receive the same or different output waveforms and the VCOM drivers  84  coupled to the fourth side  96  of the panel  44  may each receive the same or different output waveform (which may themselves be the same or different than the output waveform(s) received by the VCOM drivers  84  coupled to the third side  94  of the panel  44 ). In total, the VCOM drivers  84  will transmit the respective received output waveforms into the panel  44  resulting in an adjusted VCOM being supplied to the gate activated pixel  46  of a particular line of pixels  46 . 
       FIG. 14  illustrates the display  18  having three VCOM drivers  84  that may be coupled to the first side  88  of the panel at separate connection points  86 , a VCOM driver  84  that is coupled to the third side  94  of the panel  44  at a connection point  92 , and a VCOM driver  84  coupled to the fourth side  96  of the panel  44  at a connection point  92 . The VCOM drivers  84  coupled to the first side  88  of the panel  44  may each receive the same or different output waveforms, the VCOM driver  84  coupled to the third side  94  may receive an output waveform, and the VCOM driver  84  coupled to the fourth side  96  of the panel  44  may receive an output waveform (which may themselves be the same or different than the output waveform(s) received by the VCOM drivers  84  coupled to the first side  88  of the panel  44 ). In total, the VCOM drivers  84  will transmit the respective received output waveforms into the panel  44  resulting in an adjusted VCOM being supplied to the gate activated pixel  46  of a particular line of pixels  46 . 
       FIG. 15  illustrates the display  18  having two VCOM drivers  84  that may be coupled to the first side  88  of the panel at separate connection points  86 , two VCOM drivers  84  that are coupled to the third side  94  of the panel  44  at separate connection points  92 , and two VCOM driver  84  coupled to the fourth side  96  of the panel  44  at separate connection points  92 . The VCOM drivers  84  coupled to the first side  88  of the panel  44  may each receive the same or different output waveforms, the VCOM drivers  84  coupled to the third side  94  may each receive the same or different output waveforms, and the VCOM drivers  84  coupled to the fourth side  96  of the panel  44  may each receive the same or different output waveforms (which may themselves be the same or different than the output waveform(s) received by the VCOM drivers  84  coupled to the first side  88  of the panel  44 ). In total, the VCOM drivers  84  will transmit the respective received output waveforms into the panel  44  resulting in an adjusted VCOM being supplied to the gate activated pixel  46  of a particular line of pixels  46 . 
       FIG. 16  illustrates the display  18  having three VCOM drivers  84  that may be coupled to the first side  88  of the panel at separate connection points  86 , a VCOM driver  84  that is coupled to the second side  90 , a VCOM driver that is coupled to the third side  94  of the panel  44 , and a VCOM driver  84  that is coupled to the fourth side  96  of the panel  44 . The VCOM drivers  84  coupled to the first side  88  of the panel  44  may each receive the same or different output waveforms, and the VCOM drivers  84  coupled to the second side  90 , the third side  94 , and the fourth side  96  may each receive the same or different output waveforms which themselves may be the same or different than the output waveform(s) received by the VCOM drivers  84  coupled to the first side  88  of the panel  44 ). In total, the VCOM drivers  84  will transmit the respective received output waveforms into the panel  44  resulting in an adjusted VCOM being supplied to the gate activated pixel  46  of a particular line of pixels  46 . 
     In some embodiments, information may be collected and utilized to formulate waveforms (e.g., waveform  112 , waveform  118 , waveform  120 , and/or additional waveforms) that may be stored (e.g., in a lookup table as stored waveforms) to be transmitted to the VCOM drivers  84 . Collection of this information may be part of, for example, a factory calibration of the electronic device  10 , an internal calibration of the electronic device  10  performed, for example, when the electronic device is powered on or restarted, or the information may be collected in a different manner. The information may be, for example, utilized to generate VCOM compensation and/or a VCOM compensation map of the display  18  that may be utilized in determining and generating the VCOM waveforms that are transmitted to the VCOM drivers  84  to adjust the VCOM for selected pixels  46 . 
     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: 20180928
Publication Date: 20210810
Grant Date: 20210810
Priority Date: 20180119
Inventors: HOU, Pei-yu
LI, YANG
CHIU, HAO-LIN
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G3/3696", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2310/08", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3655", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2310/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3655", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0233", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0247", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G5/003", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2310/0243", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3225", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2320/0247", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2300/0426", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3696", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2320/0247", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3655", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2320/0233", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3225", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2310/08", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2310/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2310/0243", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 67298756