PATENT DOCUMENT

Publication Number: US-9268433-B2
Application Number: US-201213664086-A
Country: US
Kind Code: B2

Title: Devices and methods for reducing power usage of a touch-sensitive display

Abstract:
Methods and devices employing circuitry for reducing power usage of a touch-sensitive display are provided. In one example, a method for reducing power usage of a touch-sensitive display may include receiving power for the display of an electronic device. The method may also include powering a touch subsystem and a display subsystem of the display. The method may include, in a standard display mode, receiving synchronization signals at a first rate. A frame of data is stored on pixels of the display subsystem between each synchronization signal. The method may also include, in a low power display mode, receiving synchronization signals at a second rate. The second rate is less than the first rate. The method may include detecting a touch of the display via the touch subsystem between each synchronization signal.

Claims:
What is claimed is: 
     
       1. A method comprising:
 receiving power for a display of an electronic device; 
 powering a touch subsystem and a display subsystem of the display using the received power; 
 in a standard display mode, receiving a first plurality of vertical synchronization (VSYNC) signals at a first rate, wherein the first plurality of VSYNC signals are configured to initiate the storage of a frame of data on pixels of the display subsystem at the first rate; and 
 in a low power display mode:
 receiving a second plurality of VSYNC signals at a second rate, wherein the second plurality of VSYNC signals are configured to initiate the storage of a frame of data on the pixels at the second rate; and 
 detecting a touch of the display via the touch subsystem during an extended touch detection period at least partially defined according to the second plurality of VSYNC signals, wherein the second rate is less than the first rate, and wherein the extended touch detection period is the same as an extended blanking period of a data scan period corresponding to the second plurality of VSYNC signals. 
 
 
     
     
       2. The method of  claim 1 , comprising receiving the first plurality of VSYNC signals at a rate of approximately 60 Hz. 
     
     
       3. The method of  claim 1 , comprising receiving the second plurality of VSYNC signals at a rate of approximately 15 Hz. 
     
     
       4. The method of  claim 1 , wherein detecting the touch of the display comprises detecting a first touch and a second touch. 
     
     
       5. The method of  claim 1 , wherein detecting the touch of the display comprises performing a touch scan. 
     
     
       6. The method of  claim 1 , wherein detecting the touch of the display comprises performing a plurality of touch scans. 
     
     
       7. The method of  claim 1 , comprising storing the frame of data on pixels of the display subsystem between each VSYNC signal of the second plurality of VSYNC signals. 
     
     
       8. The method of  claim 7 , wherein the frame of data is stored on pixels of the display subsystem before detecting the touch of the display. 
     
     
       9. The method of  claim 1 , comprising detecting a touch of the display via the touch subsystem between each VSYNC signal of the first plurality of VSYNC signals. 
     
     
       10. The method of  claim 1 , comprising receiving a signal via the display indicating a change between the standard display mode and the low power display mode. 
     
     
       11. An electronic display comprising:
 a display subsystem comprising a plurality of pixels configured to display image data; 
 a touch subsystem configured to sense a touch of the display; and 
 display control circuitry configured to:
 receive a first plurality of vertical synchronization (VSYNC) signals at a first rate during a standard display mode, wherein the first plurality of VSYNC signals are configured to start the storage of a frame of pixel data on the plurality of pixels of the display subsystem at the first rate; 
 receive a second plurality of VSYNC signals at a second rate during a low power display mode, wherein the second plurality of VSYNC signals are configured to start the storage of a frame of pixel data on the plurality of pixels at the second rate, and wherein the second rate is less than the first rate to reduce power consumed by the electronic display; and 
 provide a frame of pixel data to the pixels of the display subsystem during a first data scan period between each VSYNC signal of the first plurality of VSYNC signals and during a second data scan period between each VSYNC signal of the second plurality of VSYNC signals, wherein the touch subsystem is configured to sense the touch of the display during a first touch detection period at least partially defined according to the first plurality of VSYNC signals and during a second touch detection period at least partially defined according to the second plurality of VSYNC signals, and wherein the second touch detection period is greater than the first touch detection period, and wherein the second touch detection period is the same as an extended blanking period of the second data scan period corresponding to the second plurality of VSYNC signals. 
 
 
     
     
       12. The electronic display of  claim 11 , wherein the display control circuitry is configured to receive a mode signal to indicate operation of the electronic display in the standard display mode or the low power display mode. 
     
     
       13. The electronic display of  claim 11 , wherein the display control circuitry is configured to operate in the standard display mode when the first plurality of VSYNC signals is received at the first rate and to operate in the low power display mode when the second plurality of VSYNC signals is received at the second rate. 
     
     
       14. An electronic display comprising:
 an electronic display; and 
 a processor communicatively coupled to the electronic display and configured to:
 in a standard display mode, provide a first frame of image data to the electronic display during a first period of time; 
 in a low power display mode, provide a second frame of image data to the electronic display during a second period of time, wherein the second period of time is greater than the first period of time; and 
 in the low power display mode, detect a touch of the electronic display during an extended touch detection period at least partially corresponding to a plurality of vertical synchronization (VSYNC) signals provided to the electronic display, wherein the plurality of VSYNC signals are configured to initiate the providing of the first frame of image data or the second frame of image data, and wherein the extended touch detection period is the same as an extended blanking period of a data scan period corresponding to the second plurality of VSYNC signals. 
 
 
     
     
       15. The electronic device of  claim 14 , wherein the processor is configured to provide the first frame of image data, the second frame of image data, the plurality of VSYNC signals, or a combination thereof, to the electronic display via a mobile industry processor interface (MIPI). 
     
     
       16. The electronic device of  claim 14 , wherein the first period of time is approximately 16 milliseconds and the second period of time is approximately 66milliseconds. 
     
     
       17. The electronic device of  claim 14 , wherein the processor is configured to detect the touch of the electronic display during a blanking period after each VSYNC signal of the plurality of VSYNC signals. 
     
     
       18. The electronic device of  claim 14 , wherein the electronic display is configured to disregard a portion of the plurality of VSYNC signals when operating in the low power display mode. 
     
     
       19. A method comprising:
 in a standard display mode:
 providing a plurality of vertical synchronization (VSYNC) signals to an electronic display at a first rate, wherein the plurality of VSYNC signals are configured to initiate the storage of a frame of data on pixels of the electronic display between each VSYNC signal of the plurality of VSYNC signals; and 
 
 in a low power display mode:
 providing the plurality of VSYNC signals to the electronic display at a second rate, wherein the second rate is less than the first rate; and d 
 detecting a touch of the electronic display during an expanded touch scan period at least partially defined according to the plurality of VSYNC signals, wherein the expanded touch scan period is the same as an expanded blanking period of a data scan period corresponding to the plurality of VSYNC signals. 
 
 
     
     
       20. The method of  claim 19 , wherein detecting the touch of the electronic display comprises detecting the touch of the electronic display after the frame of data is stored on pixels of the electronic display. 
     
     
       21. The method of  claim 19 , wherein detecting the touch of the electronic display comprises detecting a plurality of touches of the electronic display after the frame of data is stored on pixels of the electronic display. 
     
     
       22. The method of  claim 19 , comprising:
 detecting the touch of the electronic display during a first blanking period of the plurality of VSYNC signals in the standard display mode; and 
 detecting the touch of the electronic display during a second blanking period of the plurality of VSYNC signals in the low power display mode, wherein the second blanking period is greater than the first blanking period to reduce power consumed by the electronic display. 
 
     
     
       23. A method comprising:
 storing frames of data on pixels of a display at a first rate during a standard display mode, wherein the first rate corresponds to a first vertical synchronization (VSYNC) signal having a first frequency; 
 receiving a signal indicating for the display to transition to a low power display mode; 
 storing frames of data on pixels of the display at a second rate during the low power display mode, wherein the second rate corresponds to a second VSYNC signal having a second frequency, and wherein the second rate is less than the first rate; and 
 detecting a first touch of the display at a third rate greater than or equal to the second rate during the low power display mode, wherein detecting the first touch comprises detecting the first touch during a touch detection period that is the same as a blanking period between storing the frames of data on the pixels at the second rate, wherein the blanking period corresponds to the second VSYNC signal. 
 
     
     
       24. The method of  claim 23 , wherein receiving the signal comprises receiving a plurality of VSYNC signals at the second rate. 
     
     
       25. The method of  claim 23 , comprising detecting a second touch of the display at a fourth rate greater than or equal to the first rate during the standard display mode.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Non-Provisional Patent Application of U.S. Provisional Patent Application No. 61/657,661, entitled “Devices and Methods for Reducing Power Usage of a Touch-Sensitive Display”, filed Jun. 8, 2012, which are herein incorporated by reference. 
     BACKGROUND 
     The present disclosure relates generally to electronic devices and, more particularly, to reducing power usage of a touch-sensitive display of the electronic device. 
     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. 
     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 LCD devices typically provide a flat display in a relatively thin package that is suitable for use in a variety of electronic goods. In addition, such LCD devices typically use less power than comparable display technologies, making them suitable for use in battery powered devices or in other contexts where it is desirable to minimize power usage. 
     Typically, touch-sensitive LCD panels include an array of pixels for displaying images. Image data related to each pixel may be sent by a processor to the LCD panel through a driver integrated circuit (IC). The driver IC then processes the image data and transmits corresponding voltage signals to the individual pixels. The touch-sensitive LCD panels may also include touch input sensing and processing electronics such as capacitive arrays and touch controllers. Both the display panel, as well as the touch sensing electronics may add to the power consumption of the touch-sensitive LCD panel. 
     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. 
     Embodiments of the present disclosure relate to devices and methods for reducing power usage of a touch-sensitive display. By way of example, a method for reducing power usage of a touch-sensitive display may include receiving power for the display of an electronic device. The method may also include powering a touch subsystem and a display subsystem of the display. The method may include, in a standard display mode, receiving synchronization signals at a first rate. A frame of data is stored on pixels of the display subsystem between each synchronization signal. The method may also include, in a low power display mode, receiving synchronization signals at a second rate. The second rate is less than the first rate. The method may include detecting a touch of the display via the touch subsystem between each synchronization signal. 
     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 exist 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 block diagram of exemplary components of an electronic device, in accordance with present embodiments; 
         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 handheld device representing another embodiment of the electronic device of  FIG. 1 ; 
         FIG. 4  is a front view of a tablet computing device representing another embodiment of the electronic device of  FIG. 1 ; 
         FIG. 5  is a circuit diagram of components of an electronic device, in accordance with present embodiments; 
         FIG. 6  is a circuit diagram illustrating display circuitry of an electronic device, in accordance with present embodiments; 
         FIG. 7  is a timing diagram illustrating a standard display mode, in accordance with present embodiments; 
         FIG. 8  is a timing diagram illustrating a low power display mode, in accordance with present embodiments; and 
         FIG. 9  is a flowchart describing a method of operating the electronic device of  FIG. 1  in a standard display mode and a low power display mode, in accordance with present embodiments. 
     
    
    
     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 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. 
     With the foregoing in mind, a general description of suitable electronic devices that may employ touch-sensitive displays having capabilities to operate in a reduced power mode will be provided below. In particular,  FIG. 1  is a block diagram depicting various components that may be present in an electronic device suitable for use with such a display.  FIGS. 2 ,  3 , and  4  respectively illustrate perspective and front views of a suitable electronic device, which may be, as illustrated, a notebook computer, handheld electronic device, or a tablet computing device. 
     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  having display control circuitry  20  for reducing power usage in a reduced power mode, 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 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 the electronic device  10 . As will be appreciated, when a touch-sensitive display is operating in a mode where the display does not need to be updated at a high frequency, an unnecessary amount of power may be consumed by the display. As such, embodiments of the present disclosure may be employed to decrease the power consumption of the touch-sensitive display. 
     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 tablet computing device depicted in  FIG. 4 , or similar devices. It should be noted that the processor(s)  12  and/or other data processing circuitry may be generally referred to herein as “data processing circuitry.” This 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 . As presented herein, the data processing circuitry may control the power consumption of the electronic display  18  by controlling a display subsystem and touch subsystem of the electronic display  18  to operate in a standard display mode, a low power display mode, or to switch between operating in one of the standard display mode and the low power display mode. 
     In the electronic device  10  of  FIG. 1 , the processor(s)  12  and/or other data processing circuitry may be operatively coupled with the memory  14  and the nonvolatile memory  16  to execute instructions. 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. Also, 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 . 
     The display  18  may be a touch-screen (e.g., touch-sensitive) liquid crystal display (LCD), for example, which may allow users to interact with a user interface of the electronic device  10 . In some embodiments, the electronic display  18  may be a MultiTouch™ display that can detect multiple touches concurrently. For example, the display  18  may be a capacitive-touch-sensitive display capable of detecting projected capacitive touch (PCT) touch input gestures, such as a single touch, a double touch, a drag, a flick, a pinch, a rotate, a zoom, or combinations thereof. As will be described further detail, to reduce the overall power consumption of the display  18 , the display control circuitry  20  may be configured to control the display  18  to operate in one or more of a standard display mode and a low power display mode. Specifically, the display control circuitry  20  may be configured to receive one or more synchronization signals that control the frequency that image data is stored on pixels of the display  18 , and thereby may be used to control various aspects relating to power consumption of the 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 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), such as an 802.11x Wi-Fi network, and/or for a wide area network (WAN), such as a 3G or 4G cellular network. The power source  28  of the electronic device  10  may be any suitable source of power, such as a rechargeable lithium polymer (Li-poly) battery and/or an alternating current (AC) power converter. 
     The electronic device  10  may take the form of a computer 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  30 A, is illustrated in  FIG. 2  in accordance with one embodiment of the present disclosure. The depicted computer  30 A may include a housing  32 , 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  30 A, such as to start, control, or operate a GUI or applications running on computer  30 A. For example, a keyboard and/or touchpad may allow a user to navigate a user interface or application interface displayed on the display  18 . Further, the display  18  may include the display control circuitry  20  for reducing power of the display  18 , such as when the display control circuitry  20  receives an indication that the display  18  should operate in a low power display mode. 
       FIG. 3  depicts a front view of a handheld device  30 B, which represents one embodiment of the electronic device  10 . The handheld device  30 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  30 B may be a model of an iPod® or iPhone® available from Apple Inc. of Cupertino, Calif. In other embodiments, the electronic device  10  may also be a tablet computing device  30 C, as illustrated in  FIG. 4 . For example, the tablet computing device  30 C may be a model of an iPad® available from Apple Inc. 
     The handheld device  30 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 , which may display indicator icons  38 . The indicator icons  38  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, a proprietary I/O port from Apple Inc. to connect to external devices. 
     User input structures  40 ,  42 ,  44 , and  46 , in combination with the display  18 , may allow a user to control the handheld device  30 B. For example, the input structure  40  may activate or deactivate the handheld device  30 B, the input structure  42  may navigate a user interface to a home screen, a user-configurable application screen, and/or activate a voice-recognition feature of the handheld device  30 B, the input structures  44  may provide volume control, and the input structure  46  may toggle between vibrate and ring modes. A microphone  48  may obtain a user&#39;s voice for various voice-related features, and a speaker  50  may enable audio playback and/or certain phone capabilities. A headphone input  52  may provide a connection to external speakers and/or headphones. As also noted above, to reduce the power consumption of the display  18 , the display control circuitry  20  may be configured to receive one or more synchronization signals that control the frequency that image data is stored on pixels of the display  18 , and thereby may be used to control various aspects relating to power consumption of the display  18 . 
     Various components of the electronic device  10  may be used to control the power consumption of the display  18 . Accordingly,  FIG. 5  is an embodiment of a circuit diagram of certain components of the electronic device  10  that may be used to control the power consumption of the display  18 . As illustrated, the electronic device  10  may include the display  18  and various processors  12 . Specifically, the display  18  includes a display subsystem  54  and a touch subsystem  56 . The display subsystem  54  is configured to receive and display image data, while the touch subsystem  56  is configured to sense touches of the display  18 . In the present embodiment, the display control circuitry  20  may be communicatively coupled to the display subsystem  54  and the touch subsystem  56 . Although the display subsystem  54 , the touch subsystem  56 , and the display control circuitry  20  are illustrated separately, they are intended to indicate functionality of the display  18  as opposed to separate physical components of the display  18 . Accordingly, physical components of the display  18  may be in one or more of the display subsystem  54 , the touch subsystem  56 , and the display control circuitry  20 . 
     As illustrated, the processors  12  may include a power management unit (PMU)  60  and a system on chip (SOC)  62 . The PMU  60  may be used to manage the power of the electronic device  10 , and may control when power is supplied to, and removed from, other components of the electronic device  10 . For example, the PMU  60  may supply power  64  to the display  18 . Specifically, the PMU  60  may supply power  64  to both the display subsystem  54  and the touch subsystem  56 . 
     As illustrated, the SOC  62  provides image data  66  to the display  18 . Furthermore, the SOC  62  provides a synchronization signal  68  (e.g., VSYNC) to the display  18  to cause the display  18  to refresh image data stored in pixels of the display  18 . In certain embodiments, the SOC  62  may be used to control the display  18  to operate in various power modes. For example, the SOC  62  may be used to control the display  18  to operate in a standard display mode or a low power display mode. Particularly, as used herein, the “standard display mode” may refer to a display mode in which power consumed by the display subsystem  54  and the touch subsystem  56  is a combination of power used for image displaying and touch sensing under normal operating conditions. Furthermore, the “low power display mode” may refer to a display mode in which power consumed by the display subsystem  54  and the touch subsystem  56  is substantially less than the power consumed in the standard display mode. 
     In certain embodiments, the display  18  may transition between the standard display mode and the low power display mode by changing the rate that the synchronization signal  68  is provided to the display  18 . For example, during the standard display mode, the SOC  62  may provide the synchronization signal  68  to the display  18  at a standard rate (e.g., at a frequency of approximately 60 Hertz (Hz)). On the other hand, during the low power display mode, the SOC  62  may provide the synchronization signal  68  to the display at a rate that is less than the standard rate (e.g., at a frequency of approximately 15 Hz). By the SOC  62  providing synchronization signals  68  at a rate lower than a standard rate, the image data stored on pixels of the display  18  is updated less frequently, thus using less power to operate the display subsystem  54 . As a result, the overall power consumption of the display  18  may be reduced. 
     In some embodiments, the SOC  62  may provide synchronization signals  68  to the display  18  at a standard rate during both the standard display mode and the low power display mode. In such an embodiment, the SOC  62  may provide the display  18  with a mode signal  70  that controls whether the display  18  is operating in the standard display mode or the low power display mode. When controlled to operate in the standard display mode, the display  18  may operate normally. In contrast, when controlled to operate in the low power display mode, the display  18  may reduce the rate that image data stored on pixels of the display  18  is updated by skipping one or more synchronization signals  68  received. For example, the display  18  may skip every other synchronization signals  68  received. As another example, the display  18  may skip every third synchronization signals  68  received. By the display  18  skipping synchronization signals  68  received, the image data stored on pixels of the display  18  is updated less frequently, thus using less power to operate the display subsystem  54 . As a result, the overall power consumption of the display  18  may be reduced. As may be appreciated, one or more of the image data  66 , the synchronization signal  68 , and the mode signal  70  may be provided from the SOC  62  to the display  18  via a communication link (e.g., via a mobile industry processor interface (MIPI)). 
     Among the various components of an electronic display  18  may be a pixel array  100 , as shown in  FIG. 6 . As illustrated,  FIG. 6  generally represents a circuit diagram of circuitry of the display  18 . In particular, the pixel array  100  of the display  18  may include a number of unit pixels  102  disposed in a pixel array or matrix. In such an array, each unit pixel  102  may be defined by the intersection of rows and columns, represented by gate lines  104  (also referred to as scanning lines), and source lines  106  (also referred to as data lines), respectively. Although only six unit pixels  102 , referred to individually by the reference numbers  102 A- 102 F, respectively, are shown for purposes of simplicity, it should be understood that in an actual implementation, each source line  106  and gate line  104  may include hundreds or thousands of such unit pixels  102 . Each of the unit pixels  102  may represent one of three subpixels that respectively filters only one color (e.g., red, blue, or green) of light. For purposes of the present disclosure, the terms “pixel,” “subpixel,” and “unit pixel” may be used largely interchangeably. Further, in certain embodiments, pixel data supplied to the pixels  102  of the display  18  may be considered a “frame” of pixel data. 
     In the presently illustrated embodiment, each unit pixel  102  includes a thin film transistor (TFT)  108  for switching a data signal supplied to a respective pixel electrode  110 . The potential stored on the pixel electrode  110  relative to a potential of a common electrode  112 , which may be shared by other pixels  102 , may generate an electrical field sufficient to alter the arrangement of a liquid crystal layer of the display  18 . In the depicted embodiment of  FIG. 6 , a source  114  of each TFT  108  may be electrically connected to a source line  106  and a gate  116  of each TFT  108  may be electrically connected to a gate line  104 . A drain  118  of each TFT  108  may be electrically connected to a respective pixel electrode  110 . Each TFT  108  may serve as a switching element that may be activated and deactivated for a period of time based on the respective presence or absence of a scanning or activation signal on the gate lines  104  that are applied to the gates  116  of the TFTs  108 . 
     When activated, a TFT  108  may store the image signals (e.g., image data signal  66 ) received via the respective source line  106  as a charge upon its corresponding pixel electrode  110 . As noted above, the image signals stored by the pixel electrode  110  may be used to generate an electrical field between the respective pixel electrode  110  and a common electrode  112 . This electrical field may align the liquid crystal molecules within the liquid crystal layer to modulate light transmission through the pixel  102 . Thus, as the electrical field changes, the amount of light passing through the pixel  102  may increase or decrease. In general, light may pass through the unit pixel  102  at an intensity corresponding to the applied voltage from the source line  106 . 
     The display  18  also may include a source driver integrated circuit (IC)  120 , which may include a processor, microcontroller, or application specific integrated circuit (ASIC), that controls the display pixel array  100  by receiving image data  66  from the processor(s)  12  and sending corresponding image signals to the unit pixels  102  of the pixel array  100 . It should be understood that the source driver  120  may be a chip-on-glass (COG) component on a TFT glass substrate, a component of a display flexible printed circuit (FPC), and/or a component of a printed circuit board (PCB) that is connected to the TFT glass substrate via the display FPC. Further, the source driver  120  may include any suitable article of manufacture having one or more tangible, computer-readable media for storing instructions that may be executed by the source driver  120 . In addition, the source driver  120  may include the display control circuitry  20 . In some embodiments, the display control circuitry  20  is not part of the source driver  120 . 
     The source driver  120  also may couple to a gate driver integrated circuit (IC)  124  that may activate or deactivate rows of unit pixels  102  via the gate lines  104 . As such, the source driver  120  may provide timing signals  126  to the gate driver  124  to facilitate the activation/deactivation of individual rows (i.e., lines) of pixels  102 . In other embodiments, timing information may be provided to the gate driver  124  in some other manner. The display  18  may include a Vcom source  128  to provide a Vcom output to the common electrodes  112 . In some embodiments, the Vcom source  128  may supply a different Vcom to different common electrodes  112  at different times. In other embodiments, the common electrodes  112  all may be maintained at the same potential (e.g., a ground potential) while the display  18  may be on. 
     In certain embodiments, the display control circuitry  20  may store instructions in a storage device  130 . The instructions may be used to control the display  18  to operate in one of the standard display mode, the low power display mode, or to switch between the standard display mode and the low power display mode. Such instructions may be based on the receipt of the mode signal  70 , as described above. In embodiments that do not include the mode signal  70 , such instructions may not be necessary because the change in rate of the synchronization signals  68  automatically produces the desired results (e.g., changes the rate that data is stored in pixels  102 ). As may be appreciated, the storage device  130  may be any suitable article of manufacture having a tangible, computer-readable media for storing instructions for the display control circuitry  20 . For example, the storage device  130  may be an EEPROM device. It should be noted that the display  18  may receive and detect touch inputs during the standard display mode and the low power display mode. 
       FIG. 7  illustrates a timing diagram  140  that shows the timing of a synchronization signal  142 A (e.g., VSYNC), data scan  144 A, and a touch scan  146 A (e.g., a time period where the display  18  scans for a touch) in the standard display mode. In certain embodiments, the synchronization signal  142 A may include rising edges  148 , which may each be detected by the display  18  to identify when a data scan  144 A should begin. The logical high portions of the data scan  144 A may represent time periods where a frame of data is stored in pixels  102  of the display  18 . In the illustrated embodiment, the rising edges  148  of the synchronization signals  142 A may occur at a standard rate (e.g., approximately 60 Hz). Consequentially, the data scans  144 A may also occur at the standard rate. As may be appreciated, the data scans  144 A may include a blanking period  154 A (e.g., a time period where data is not stored in pixels  102  of the display  18 ), which may be represented as the logic low portions between the logical high portions of the data scans  144 A. For example, in the standard display mode, the blanking periods  154 A may be approximately 5 ms, 10 ms, 16 ms, 32 ms, and so forth. 
     In certain embodiments, for example, blanking periods  154 A may be proportional to the refresh rate of the display  18  operating in the standard display mode (e.g., at a refresh rate of approximately 60 Hz, the time blanking periods  154 A may be approximately 16 ms). In other embodiments, for example, the blanking periods  154 A may be substantially the time it may take for the display control circuitry  20  to store a frame of pixel data in the pixels  102  of the display  18  (e.g., the time that the data scan  144 A is logically high). In the present embodiment, the touch scan  146 A may be performed during any time period where the touch scan  146 A is logically high (e.g., during the blanking periods  154 A), such that touch inputs on the display  18  may be sensed between the times that the display  18  is refreshed with frames of pixel data. In certain embodiments, the touch scan  146 A may be controlled to be logically high during a front porch portion of the blanking periods  154 A. 
     In certain embodiments, the frequency of the synchronization signal  142 A may be reduced, such that the data scan  144 A may include longer (e.g., extended) blanking periods  154 A to reduce power consumption of the display  18 . For example,  FIG. 8  illustrates an embodiment of a timing diagram  148  that shows the timing of a synchronization signal  142 B, data scan  144 B, and a touch scan  146 B in the low power display mode. Moreover, the synchronization signal  142 B is provided to the display  18  at a rate lower than that provided in the standard display mode. As depicted, the logical high portions of the data scan  144 B are delayed by the blanking periods  154 B. Therefore, the length of time of the logic high portions of the touch scan  146 B is increased up to approximately the time of the blanking periods  154 . For example, if the blanking periods  154  were approximately 50 ms, the touch scan  146 A may be driven to logical highs during for approximately 50 ms. Thus, in the low power display mode, the display  18  may receive and/or store frames of pixel data at a reduced rate. Accordingly, power consumed by receiving and/or storing pixel data may be reduced. Therefore, the overall power consumption of the display  18  may be reduced (e.g., while the display  18  is in a primarily touch sensing mode). 
     Turning now to  FIG. 9 , a flowchart is presented, illustrating an embodiment of a method  160  for reducing power consumption in the display  18  (e.g., a touch-sensitive display). In certain embodiments, the method  160  may be executed by code (e.g., instructions) stored in the storage  130  of the display control circuitry  20 . The method  160  includes receiving power to power the display  18  to perform, for example, functions that may include displaying image data and/or receiving and processing touch inputs (block  162 ). Accordingly, the method  160  may also include powering the touch subsystem  56  (e.g., touch sensing and/or touch processing electronics) and the display subsystem  54  of the display  18  (block  164 ). A determination is made at block  166  as to whether the display  18  is operating in the standard display mode or the low power display mode. If the display  18  is operating in the standard display mode, the display  18  may receive at first set of synchronization signals  68  (e.g., VSYNC) at a first rate (e.g., 60 Hz) (block  168 ). The display  18  may also detect one or more touch inputs between each of the synchronization signals  68  of the first set of synchronization signals  68  received at the first rate (block  170 ). However, if operating in the low power display mode, the display  18  may receive a second set of synchronization signals  68  (e.g., VSYNC) at a second rate (e.g., 15 Hz) (block  172 ). The display  18  may also detect one or more touch inputs between each of the synchronization signals  68  of the second set of synchronization signals  68  received at the second rate (block  174 ). Accordingly, the method  160  may be useful in reducing the overall power consumption of the display  18  by, specifically, reducing the power consumption of the display subsystem  54 , while sustaining the activity of the touch subsystem  56 . 
     The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.

Metadata:
Filing Date: 20121030
Publication Date: 20160223
Grant Date: 20160223
Priority Date: 20120608
Inventors: AL-DAHLE AHMAD
BAE HOPIL
Assignee: APPLE INC
CPC Classifications: [{"code": "G09G3/3648", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/3262", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2340/0435", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/3265", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2330/021", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y02B60/1242", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/3262", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/04166", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y02D10/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y02D10/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2340/0435", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G2330/021", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/3262", "inventive": true, "first": true, "tree": "[]"}, {"code": "G09G2340/0435", "inventive": false, "first": false, "tree": "[]"}, {"code": "G09G3/3648", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/3265", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04166", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G2330/021", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F1/3265", "inventive": true, "first": false, "tree": "[]"}, {"code": "G09G3/3648", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 49714878