Patent Publication Number: US-8115726-B2

Title: Liquid crystal display image presentation

Description:
BACKGROUND 
     Many electronic devices include color liquid crystal displays (LCDs). Some LCDs utilize a white backlight, which is passed through at least one color filter to make different colors available to the LCD screen. Pixels on the LCD screen are arranged to groups of three, which include a red pixel, a green pixel, and a blue pixel. By managing the intensity of the red, green, and blue pixels, colors are presented on the screen. 
     Liquid crystal display devices have relatively high capacitance, which results in relatively slow response times. Thus, video or graphic streams which include regions of high motion may exhibit blurring when displayed on the liquid crystal display. The blurring reduces image quality. Thus, liquid crystal display assemblies that include or implement techniques to reduce motion-induced blurring may find utility. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic, front view of a LCD assembly, according to an embodiment. 
         FIG. 1B  is an exploded, side view of a LCD assembly, according to an embodiment. 
         FIG. 2  is a flowchart illustrating operations in an embodiment of a method for liquid crystal display image presentation. 
         FIG. 3  is a schematic illustration of components of a display system adapted to implement liquid crystal display image presentation, according to an embodiment. 
         FIG. 4  is a schematic illustration of a portion of a liquid crystal display in which pixels are shifted to implement liquid crystal display image presentation, according to an embodiment. 
         FIG. 5  is a schematic illustration of a computing system which includes a liquid crystal display that implements image presentation, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Described herein are exemplary systems and methods for implementing image presentation in a liquid crystal display. In the following description, numerous specific details are set forth to provide a thorough understanding of various embodiments. However, it will be understood by those skilled in the art that the various embodiments may be practiced without the specific details. In other instances, well-known methods, procedures, components, and circuits have not been illustrated or described in detail so as not to obscure the particular embodiments. 
       FIG. 1A  is a schematic, front view of a LCD assembly, according to an embodiment, and  FIG. 1B  is an exploded, side view of a LCD assembly, according to an embodiment. Referring to  FIG. 1A , a display assembly  100  comprises a base  110  and a monitor assembly  120  coupled to the base. Monitor assembly  120  comprises a housing  122 , which houses a LCD assembly  130 . 
     Referring to  FIG. 1B , LCD assembly  130  comprises a timing controller  132 , a backlight assembly  134 , a diffuser  142 , a LCD module  144 , and a light directing film  146 . Display assembly  100  may be embodied as any type of color graphics display. In one embodiment, LCD module  144  may comprise a thin film transistor (TFT) assembly. In other embodiments, the LCD module  144  may embodied as a different type of LCD, e.g., a diode matrix or another capacitively driven LCD, a digital mirror assembly, or the like. 
     A diffuser  142  is positioned adjacent the backlight assembly  134 . In some embodiments, diffuser  142  may also act as a polarizer to polarize light emitted by the arrays of LEDs  136 ,  138 ,  140 . A LCD module  144  is positioned adjacent diffuser  142 . In some embodiments, LCD module may be a twisted nematic LCD, an In-plane switching LCD, or a vertical alignment (VA) LCD. In some embodiments, a light directing film  146  may be positioned adjacent the LCD to enhance the brightness of the display. 
     In some embodiments, a liquid crystal display device may be adapted to implement operations for image presentation that accommodate both regions of high motion and regions of low motion. Structural components of such a liquid crystal display device and associated operations will be explained with reference to  FIGS. 2-4 .  FIG. 2  is a flowchart illustrating operations in an embodiment of a method for liquid crystal display image presentation.  FIG. 3  is a schematic illustration of components of a display system adapted to implement liquid crystal display image presentation, according to an embodiment.  FIG. 4  is a schematic illustration of a portion of a liquid crystal display in which pixels are shifted to implement liquid crystal display image presentation, according to an embodiment. 
     In some embodiments, the operations depicted in  FIG. 2  may be implemented by a controller such as the controller  132  depicted in  FIG. 1B , alone or in combination with a graphics controller or another controller is part of a computing system. 
     Referring to  FIG. 2 , at operation  210  an image is received in the controller. For example, in the embodiment depicted in  FIG. 3  an image comprising video and/or graphics content is received in graphics controller  310 . At operation  220  the stationary, or low-motion, portions of the received image are separated from the moving, or high-motion portions of the received image. For example, in some embodiment the graphics controller  310  may implement a routine which analyzes corresponding pixels in successive image frames to separate low-motion pixels from high-motion pixels. The result of such analysis may be accumulated as history data and tracked continuously. Regions of the image in which there are significant changes between corresponding pixels in successive image frames may be classified as high motion regions. By contrast, regions of the image in which there are not significant changes between corresponding pixels in successive image frames may be classified as low motion regions. 
     At operation  225  the stationary, or low-motion, regions of the image are presented on the display at a first refresh rate, and that operation  230  the moving, or high-motion, regions of the image are presented on the display at a second refresh rate. In some embodiments the second refresh rate is approximately three times faster than the first refresh rate. 
     Referring again to  FIG. 3 , high-motion regions of the video are broken down into their constituent red, green, and blue components, as indicated by blocks  312 ,  314 , and  316 . Similarly, low-motion regions of the video are broken down into their constituent red, green, and blue components, as indicated by blocks  318 ,  320  and  322 . The red, green, and blue components  312 ,  314 , and  316  are passed to a framer  330  where they are inserted into three separate frames indicate by blocks  332 A,  334 A, and  336 A. The red, green, and blue components  318 ,  320  and  322  are passed to the framer  330  where they are inserted into a single frame indicated by block  338 A. 
     The frames indicated by block&#39;s  332 A,  334 A,  336 A,  338 A are passed to a controller  340  (frames  332 A,  334 A,  336 A, and  338 A in the framer  330  correspond to frames  332 B,  334 B,  336 B, and  338 B, respectively, in the controller  340 ). In one embodiment, controller  340  may correspond to the controller  132  depicted in  FIG. 1B , and may implement timing control operations and frame control operations of a display. Controller  340  presents the frame  338 B from the low motion portion of the video input on the display at a first refresh rate indicated in  FIG. 3  by the timing arrow T 1 . By contrast, controller  340  presents the frames  332 B,  334 B, and  336 B from the high motion portion of the video input on the display at a second refresh rate such that all three frames are presented during the time period T 1  represented by the first refresh rate. For example, in one embodiment the second refresh rate may be approximately three times the first refresh rate. 
     Thus, the structure and operations depicted in  FIGS. 2-3  permit a liquid crystal display to implement a time-multiplexing process pursuant to which high-motion components of a video stream are presented at a higher refresh rate than low-motion components of a video input. One skilled in the art will recognize that the operations implemented by  FIG. 3  may be performed on individual pixels in an image, or on groups of one or more pixels in an image. Such groups of one or more pixels can be rectangular or other shapes. Thus, the structure depicted in  FIG. 3  may implemented as logic circuitry, and may be replicated as necessary in order to process pixels in parallel to achieve desired performance standards. 
     In addition to the time multiplexing function implemented by  FIGS. 2-3 , a pixel shifting operation may be implemented in which frames  332 B,  334 B, and  336 B of the high-motion portion(s) of the video input are shifted during the presentation on the display. Such separation of high motion pixels from the low motion pixels to apply different operation inhibits low motion pixels from being processed through the shifting operation. This can prevent undesired image jitter of low motion, high frequency display area such as overlay text (i.e., captions or subtitles). 
     Referring to  FIG. 4 , pixels on a color liquid crystal display  400  are arranged to groups of three, which include a red pixel, a green pixel, and a blue pixel. In one embodiment the controller  340  shifts frames  332 B,  334 B, and  336 B by one pixel during the refresh cycle. Thus, frame  332 B is displayed at time T 1  across an array of pixels arranged in red-green-blue (RGB) order. During the next refresh cycle frame  334 B is displayed at time T 2  and shifted one pixel such that frame  334 B is displayed across an array of pixels arranged in GBR order. During the next refresh cycle frame  336 B is displayed at time T 3  and shifted one pixel such that frame  336 B is displayed across an array of pixels arranged in BRG order. 
     The time multiplexing of high-motion pixels, alone or in combination with the physical shifting of the frame position associated with high-motion pixels on the display reduces motion-induced blurring in image display. 
     In some embodiments, a display assembly may be distributed as a component of a computer system.  FIG. 5  is a schematic illustration of a computing system which includes a liquid crystal display that implements image presentation, according to an embodiment. The components shown in  FIG. 5  are only examples, and are not intended to suggest any limitation as to the scope of the functionality of the invention; the invention is not necessarily dependent on the features shown in  FIG. 5 . In the illustrated embodiment, computer system  500  may be embodied as a hand-held or stationary device for accessing the Internet, a desktop PCs, notebook computer, personal digital assistant, or any other processing devices that have a basic input/output system (BIOS) or equivalent. 
     The computing system  500  includes a computer  508  and one or more accompanying input/output devices  506  including a display  502  having a screen  504 , a keyboard  510 , other I/O device(s)  512 , and a mouse  514 . The other device(s)  512  may include, for example, a touch screen, a voice-activated input device, a track ball, and any other device that allows the system  500  to receive input from a developer and/or a user. 
     The computer  508  includes system hardware  520  commonly implemented on a motherboard and at least one auxiliary circuit boards. System hardware  520  including a processor  522  and a basic input/output system (BIOS)  526 . BIOS  526  may be implemented in flash memory and may comprise logic operations to boot the computer device and a power-on self-test (POST) module for performing system initialization and tests. In operation, when activation of computing system  500  begins processor  522  accesses BIOS  526  and shadows the instructions of BIOS  526 , such as power-on self-test module, into operating memory. Processor  522  then executes power-on self-test operations to implement POST processing. 
     Graphics controller  524  may function as an adjunction processor that manages graphics and/or video operations. Graphics controller  524  may be integrated onto the motherboard of computing system  500  or may be coupled via an expansion slot on the motherboard. 
     Computer system  500  further includes a file store  580  communicatively connected to computer  508 . File store  580  may be internal such as, e.g., one or more hard drives, or external such as, e.g., one or more external hard drives, network attached storage, or a separate storage network. In some embodiments, the file store  580  may include one or more partitions  582 ,  584 ,  586 . 
     Memory  530  includes an operating system  540  for managing operations of computer  508 . In one embodiment, operating system  540  includes a hardware interface module  554  that provides an interface to system hardware  520 . In addition, operating system  540  includes a kernel  544 , one or more file systems  546  that manage files used in the operation of computer  508  and a process control subsystem  548  that manages processes executing on computer  508 . Operating system  540  further includes one or more device drivers  550  and a system call interface module  542  that provides an interface between the operating system  540  and one or more application modules  562  and/or libraries  564 . The various device drivers  550  interface with and generally control the hardware installed in the computing system  500 . 
     In operation, one or more application modules  562  and/or libraries  564  executing on computer  508  make calls to the system call interface module  542  to execute one or more commands on the computer&#39;s processor. The system call interface module  542  invokes the services of the file systems  546  to manage the files required by the command(s) and the process control subsystem  548  to manage the process required by the command(s). The file system(s)  546  and the process control subsystem  548 , in turn, invoke the services of the hardware interface module  554  to interface with the system hardware  520 . The operating system kernel  544  can be generally considered as one or more software modules that are responsible for performing many operating system functions. 
     The particular embodiment of operating system  540  is not critical to the subject matter described herein. Operating system  540  may be embodied as a UNIX operating system or any derivative thereof (e.g., Linux, Solaris, etc.) or as a Windows® brand operating system or another operating system. 
     Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least an implementation. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. 
     Thus, although embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that claimed subject matter may not be limited to the specific features or acts described. Rather, the specific features and acts are disclosed as sample forms of implementing the claimed subject matter.