This application is a Non-Provisional patent application of U.S. Provisional Patent Application No. 62/221,503, entitled “Devices and Methods for Discharging or Harvesting VCOM Charge in Electronic Displays”, filed Sep. 21, 2015, which is herein incorporated by reference in its entirety and for all purposes.
The resent disclosure relates generally to electronic displays and, more particularly, to electronic displays with reduced or eliminated mura artifacts or to recovering charge buildup on display for useful purposes.
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.
Electronic displays may be found in a variety of devices, such as computer monitors, televisions, instrument panels, mobile phones, clocks, wearable devices, virtual reality (VR) devices, automobiles, and so forth. One type of electronic display, known as a liquid crystal display (LCD), displays images by modulating the amount of light allowed to pass through a liquid crystal layer within pixels of the LCD. In general, LCDs modulate the light passing through each pixel by varying a voltage difference between a pixel electrode and a common electrode (VCOM). This creates an electric field that causes the liquid crystal layer to change alignment. The change in alignment of the liquid crystal layer causes more or less light to pass through the pixel. By changing the voltage difference supplied to each pixel, images are produced on the LCD.
Another type of electronic display, known as an organic light-emitting diode (OLED) display, which may include light-emitting devices including one or more layers of organic materials interposed between a pixel electrode and a common electrode (VCOM). Specifically, the OLED display may display images by driving individual OLED pixels to store image data and image brightness data. In either case of LCDs or OLEDs, bias voltages or other voltage perturbations coupling to the VCOM could produce visible artifacts known as muras or flicker. Furthermore, for certain displays such as, for example, displays in mobile phones, wearable devices, VR devices, or automobile heads-up displays (HUDs), VCOM voltage may couple to one or more sources of electromagnetic radiation. It may be useful to provide electronic displays with reduced or eliminated mura or flicker artifacts.
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.
Various embodiments of the present disclosure relate to methods and devices for discharging an aberrant charge on the common voltage electrode (VCOM) of an electronic display. By way of example, a method may include supplying an activation signal to an active switching device of an electronic display. The active switching device is configured to discharge an aberrant charge on a common electrode of the electronic display. The method further includes discharging the aberrant charge by way of the active switching device. Discharging the aberrant charge comprises preventing a possible occurrence of image artifacts from becoming apparent on the electronic display.
Embodiments of the present disclosure relate to methods and devices for harvesting energy from the VCOM of an electronic display. By way of example, a method may include receiving one or more inputs from a common electrode of an electronic display based on an aberrant charge on the common electrode, converting the one or more inputs based on the aberrant charge into a useable energy, and storing or utilizing the useable energy to power one or more functions of the electronic display.
Various refinements of the features noted above may exist 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 exist individually or in any combination. For example, 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.
Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:
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' 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.
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.
Embodiments of the present disclosure relate to methods and devices for discharging an aberrant charge on the common voltage electrode (VCOM) of an electronic display and harvesting energy from the VCOM of the electronic display (e.g., a VCOM of a liquid crystal display (LCD) or an organic light-emitting diode (OLED) display). Indeed, the present embodiments may include technique of placing a first active switch (e.g., transistor) across the pixel electrode and common electrode of pixels of the electronic display. The gate of the first active switch may be coupled to a voltage source (e.g., high direct current (DC) voltage output) of charge pump circuitry that may be used to collect energy from one or more disturbance charges (e.g., due to a user touch of the electronic display and/or electromagnetic interference (EMI)) appearing on the VCOM of the electronic display. Specifically, the first active switch may be used to provide a discharge path from the VCOM to the data line of the electronic display to discharge the aberrant charge when the electronic display is “OFF” (e.g., deactivated or temporarily inactive).
In some embodiments, the present techniques may also include providing a second active switch (e.g., pull-down transistor) coupled to the gate of the first active switch. The second active switch may be used to pull the voltage of the gate of the first active switch to ground (e.g., approximately 0 volts (V)) when the electronic display “ON” (e.g., activated). In other embodiments, the present techniques may include providing a multiplexer (MUX) to select between a gate signal of a thin-film transistor (TFT) of a pixel of the electronic display and the voltage source (e.g., high direct current (DC) voltage output) of charge pump circuitry to discharge the aberrant charge when the electronic display is “OFF” (e.g., deactivated or temporarily inactive). Specifically, the MUX may select the gate signal when the electronic display “ON” (e.g., activated), and select the voltage source signal when the electronic display is “OFF” (e.g., deactivated or temporarily inactive. In this way, the possibility of image artifacts becoming apparent on the electronic display due to the aberrant charge may be reduced or substantially eliminated. Furthermore, in some embodiments, the aberrant charge on the VCOM may be stored or utilized to power one or more functions of the electronic display or of an electronic device encompassing the electronic display.
With the foregoing in mind, a general description of suitable electronic devices that may include a display and data processing circuitry useful in discharging an aberrant charge on the VCOM of an electronic display and harvesting energy from the VCOM of the electronic display is provided. Indeed, while the present embodiments may be discussed henceforth with respect to embodiments of a notebook computer 30A, a handheld device 30B, handheld device 30C, a computer 30D, and wearable electronic device 30E, it should be appreciated that the present techniques may be applied in any of various electronic displays such as, for example, electronic displays utilized in virtual reality (VR) and/or augmented reality (AR) systems and devices, head-up displays (HUDs) utilized in automobiles and other similar systems, head-mounted displays (HMDs), as well as numerous other technologies utilizing various forms of electronic displays.
Turning first to
By way of example, the electronic device 10 may represent a block diagram of the notebook computer depicted in
In the electronic device 10 of
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. Further, in some embodiments, the display 18 may include a light source (e.g., backlight) that may be used to emit light to illuminate displayable images on the display 18. Indeed, in some embodiments, as will be further appreciated, the light source (e.g., backlight) may include any type of suitable lighting device such as, for example, cold cathode fluorescent lamps (CCFLs), hot cathode fluorescent lamps (HCFLs), and/or light emitting diodes (LEDs), or other light source that may be utilize to provide highly backlighting.
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 interfaces 26. The network interfaces 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 3rd generation (3G) cellular network, 4th generation (4G) cellular network, or long term evolution (LTE) 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.
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 30A, is illustrated in
The handheld device 30B 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, which may display indicator icons 39. The indicator icons 39 may indicate, among other things, a cellular signal strength, Bluetooth connection, and/or battery life. 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 42, in combination with the display 18, may allow a user to control the handheld device 30B. For example, the input structure 40 may activate or deactivate the handheld device 30B, the input structure 42 may navigate user interface to a home screen, a user-configurable application screen, and/or activate a voice-recognition feature of the handheld device 30B, the input structures 42 may provide volume control, or may toggle between vibrate and ring modes. The input structures 42 may also include a microphone may obtain a user's voice for various voice-related features, and a speaker may enable audio playback and/or certain phone capabilities. The input structures 42 may also include a headphone input may provide a connection to external speakers and/or headphones.
Turning to
Similarly,
In certain embodiments, as previously noted above, each embodiment (e.g., notebook computer 30A, handheld device 30B, handheld device 30C, computer 30D, and wearable electronic device 30E) of the electronic device 10 may include a display 18. Indeed, as will be further appreciated with respect to
Turning now to
Although only nine unit pixels, referred to individually by the reference numbers 40, respectively, are shown for purposes of illustration, it should be understood that in an actual implementation, each source line 44 and gate line 42 may include hundreds, thousands, or millions of such unit pixels 40. By way of example, in a color display 18 having a display resolution of 1024×768, each source line 44, which may define a column of the pixel array, may include 768 unit pixels, while each gate line 42, which may define a row of the pixel array, may include 1024 groups of unit pixels, wherein each group may include a red, blue, and green pixel, thus totaling 3072 unit pixels per gate line 42.
Although a display resolution of 1024×768 is mentioned by way of example above, the display 18 may include any suitable number of pixels. As may be appreciated, in the context of LCDs, the color of a particular unit pixel generally depends on a particular color filter that is disposed over a liquid crystal layer of the unit pixel. In the presently illustrated example, the group of unit pixels 40a-40c may represent a group of pixels having a red pixel (40a), a blue pixel (40b), and a green pixel (40c). The group of unit pixels 40d-40f may be arranged in a similar manner.
As shown in the present embodiment, each unit pixel 40 may include a thin film transistor (TFT) 46 for switching a respective pixel electrode 48. In the depicted embodiment, the source 50 of each TFT 46 may be electrically connected to a source line 44. Similarly, the gate 52 of each TFT 46 may be electrically connected to a gate line 42. Furthermore, the drain 54 of each TFT 46 may be electrically connected to a respective pixel electrode 48. Each TFT 46 serves as a switching element which may be activated (e.g., turned “ON” or is active) and deactivated (e.g., turned “OFF” or is temporarily inactive) for a predetermined period based upon the respective presence or absence of a scanning signal at the gate 52 of the TFT 46.
For example, when activated, the TFT 46 may store the image signals received via a respective source line 44 as a charge its corresponding pixel electrode 48. The image signals stored by pixel electrode 48 may be used to generate an electrical field between the respective pixel electrode 48 and a common voltage electrode 56 (VCOM). As discussed above, the pixel electrode 48 and the common electrode 56 may form a liquid crystal capacitor for a given unit pixel 40. Thus, in an LCD display 18, such an electrical field may align liquid crystals molecules within a liquid crystal layer to modulate light transmission through a region of the liquid crystal layer that corresponds to the unit pixel 40. For example, light may be transmitted through the unit pixel 40 at an intensity corresponding to the applied voltage (e.g., from a corresponding source line 44).
The display 18 also may include a source driver integrated circuit (IC) 58 (e.g., column driver), which may include a chip, such as a processor or ASIC, that is configured to control various aspects of display 18 and panel 30. For example, the source driver IC 58 may receive image data from the processor(s) 12 and send corresponding image signals to the unit pixels 40 of the display 18. The source driver IC 58 may also be coupled to a gate driver IC 60, which may be configured to activate or deactivate rows of unit pixels 40 via the gate lines 42. As such, the source driver IC 58 may send timing information to gate driver IC 60 to facilitate activation and/or deactivation of individual rows of pixels 40.
In other embodiments, timing information may be provided to the gate driver IC 60 in some other manner. While the illustrated embodiment shows only a single source driver IC 58 coupled to display 18 for purposes of simplicity, it should be appreciated that additional embodiments may utilize multiple source driver ICs 58 for providing image signals to the pixels 40. For example, additional embodiments may include multiple source driver ICs 58 disposed along one or more edges of the display 18, in which each source driver IC 58 is configured to control a subset of the source lines 44 and/or gate lines 42.
In certain embodiments, the source driver IC 58 may receive image data from the processor(s) 12, and, based on the received data, outputs signals to control the pixels 40. For example, to display image data, the source driver IC 58 may adjust the voltage of the pixel electrodes 48 one row at a time. To access an individual row of pixels 40, the gate driver IC 60 may send an activation signal to the TFTs 46 associated with the particular row of pixels 40 being addressed. This activation signal may render the TFTs 46 on the addressed row conductive. Accordingly, image data corresponding to the addressed row may be transmitted from source driver IC 58 to each of the unit pixels 40 within the addressed row via respective source lines 44. Thereafter, the gate driver IC 60 may deactivate the TFTs 46 in the addressed row, thereby impeding the pixels 40 within that row from changing state until the next time they are addressed. The above-described process may be repeated for each row of pixels 40 in the display 18 to reproduce image data as a viewable image on the display 18.
In some embodiments, the common electrode 56 of the display 18 may include one or more common voltage electrode (VCOM) plates 64. This arrangement may produce separate groups of pixels that are each associated with a different VCOM plate 64. For example,
In certain embodiments, when the display 18 is in the “OFF” mode (e.g., deactivated or temporarily inactive), any charge disturbance signal (e.g., which may be due to a user touch, EMI, and so forth) coupling, for example, to the VCOM plate 64 may cause image artifacts (e.g., flicker or other mura artifacts) to become apparent on the display 18. For example, as illustrated by the timing diagram 72 of
Thus, as will described in further detail below, it may be useful to provide techniques for discharging any disturbance charge and/or other aberrant charge on the VCOM plate 64 and/or common electrode 56 of the display 18, and, further, techniques to harvest any disturbance charge or other aberrant charge from the VCOM plate 64 and/or common electrode 56 to be converted into usable energy for the display 18 or the electronic device 10. For example, by applying the presently disclosed techniques, a charge signal 79 may remain below the acceptable flicker threshold level 78 when the display 18 switches from “OFF” (e.g., deactivated or temporarily inactive) to “ON” (e.g., active).
Discharging of Aberrant Charge on VCOM
Turning now to
For example, in certain embodiments, when a disturbance charge (e.g., as illustrated by the capacitance 96 (“CDisturbance”)) is detected or becomes apparent on the VCOM plate 64, the active switch 80 may turn “ON” (e.g., activate). Specifically, when any disturbance charge or other aberrant charge accumulates on the VCOM plate 64, current may flow into the pixel capacitance 83 (e.g., CPixel coupled across the pixel electrode 48 and the common electrode 56). Thus, a voltage may accumulate across the pixel capacitance 83 until the pixel capacitance 83 becomes completely charged. However, by activating the active switch 80 (e.g., “MPixel”), the active switch 80 (e.g., “MPixel”) may turn “ON” and act, for example, as a short circuit path (e.g., operate in the saturation mode) through which current may flow across a first terminal 86 to a second terminal 88 of the active switch 80, and finally through the TFT 46 to the data line 44. Thus, the active switch 80 (e.g., “MPixel”) may discharge the VCOM plate 64 during the time the display 18 is “OFF.”
In some embodiments, the active switch 82 (e.g., “MEnable”) may be provided to control the operation of the active switch 80 (e.g., “MPixel”), and more specifically, control when the active switch 80 (e.g., “MPixel”) turns “ON” and turns “OFF.” For example, in some embodiments, the active switch 82 (e.g., “MEnable”) may receive a “Power Enable” signal (e.g., direct current (DC) voltage signal or other voltage signal) that may be used to turn “ON” of the active switch 82. Once “ON” (e.g., activated), the active switch 82 (e.g., “MEnable”) may provide a signal to the gate 84 of the active switch 80 (e.g., “MPixel”) to activate the active switch 80 (e.g., “MPixel”).
For example, in one embodiment, the active switch 82 (e.g., “MEnable”) may be a pull-down transistor positioned at the gate 84 of the active switch 80 (e.g., “MPixel”) that may be used to “hide” (e.g., cause the active switch 80 (“MPixel”) to switch “OFF” or enter into the cutoff mode) during the time the display 18 is “ON,” and will thus only cause the active switch 80 (e.g., “MPixel”) to t turn an “ON” when a disturbance charge is detected or becomes apparent on the VCOM plate 64 (e.g., when the display 18 is “OFF”). Specifically, the active switch 82 (e.g., “MPixel”) may be used to pull the voltage on the gate 84 of the active switch 80 (e.g., “MPixel”) to t ground (e.g., approximately 0 V) or otherwise cause the active switch 80 (e.g., “MPixel”) to act as an “open circuit” during the time the display 18 is “ON.” In other embodiments, as will be further appreciated below, the active switch 80 (e.g., “MPixel”) may be directly activated 1 by a voltage source (e.g., DC voltage source) 98.
In certain embodiments, as further depicted, the MUX 100 may be coupled to the gate 52 of the TFT 46 to control the TFT 46 to turn “ON” and “OFF.” Specifically, when the “Power Enable” signal is logically low (e.g., when the display is “OFF”), the MUX 100 may provide the voltage signal 98 to the gate 52 of the TFT 46 to discharge the VCOM plate 64, such that any disturbance charge (e.g., due to a user touch or other disturbance) or other aberrant charge may be discharged to the data line 44. Otherwise, when the “Power Enable” signal is logically high (e.g., when the display is “ON”), the MUX 100 may provide the gate signal 102 to the gate 52 of the TFT 46. In this way, the possibility of image artifacts becoming apparent on the display 18 may be reduced or substantially eliminated.
Turning now to
Harvesting Energy from Aberrant Charge on VCOM
In some embodiments, the input voltage signal 116 (“VIn”) and the clock signals 118 and 120 (“ϕ1” and “ϕ2”) may be generated based on, for example, a disturbance charge or the capacitance 96 (“CDisturbance”) detected or becoming apparent on the VCOM plate 64 and/or the common electrode 56. In another embodiment, the clock signals may also be generated from any combination of existing clock signals in the electrical system, including but not limited to the CPU clock, GPU clock, SoC clock, WLAN clock, Bluetooth clock, and memory clock. Similarly, the clock signals may also be generated from only one of these existing clock signals by passing that signal through an inverter or delay elements, including but not limited to capacitors, inductors, flip-flops, and transmission lines.
As further depicted, the charge pump circuitry 112 may include a number of diodes 122 (e.g., diode chain), which may be used as timing switches that may successively turn “ON.” Indeed, during operation, the charge pump circuitry 112 may boost a charge along the number of diodes 122 (e.g., diode chain) while the capacitors 118 and 120 may be successively charged and discharged during each cycle of the clock signals 118 and 120 (“ϕ1” and “ϕ2”), respectively. As further depicted, and as will be better appreciated with respect to
Similarly, as depicted in
Vout=k*VIn, where k is a constant>1.
As a further example,
Turning now to
The process 148 may begin with the one or more processor(s) 12 and/or other the charge pump circuitry 112 receiving (block 150) a number of inputs from the VCOM of a display based on an aberrant charge on the display. For example, the charge pump circuitry 112 may receive the input voltage signal 116 (“VIn”), the input clock signal 118 (“φ1”), and the input clock signal 120 (“φ2”). The process 148 may continue with the one or more processor(s) 12 and/or the charge pump circuitry 112 converting (block 152) the inputs into a useable or storable voltage, current, and/or energy in the form of electric and/or magnetic fields. The process 148 may conclude with the one or more processor(s) 12 and/or the charge pump circuitry 112 storing (block 154) the usable voltage, current, and/or energy or utilizing the useable voltage and/or energy to power functions of the display or the electronic device including the display. For example, the charge pump circuitry 112 may generate an output voltage signal (“VOut”) 146 that may be provided to the other circuitry or energy storage 114 (e.g., operational circuitry, a battery, or an inductor) to be used by the display 18 and/or electronic device 10.
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.
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Number | Date | Country | |
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Number | Date | Country | |
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62221503 | Sep 2015 | US |