News Column

Patent Issued for Overdrive Apparatus and Associated Method for Display System

July 23, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- MStar Semiconductor, Inc. (Hsinchu Hsien, TW) has been issued patent number 8773412, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.

The patent's inventors are Lee, Wei-Kuo (Hsinchu Hsien, TW); Chiang, Hsin-Chun (Hsinchu Hsien, TW).

This patent was filed on May 10, 2011 and was published online on July 8, 2014.

From the background information supplied by the inventors, news correspondents obtained the following quote: "The invention relates in general to an overdrive apparatus and associated method applied to a display system, and more particularly to overdrive apparatus and associated method that provides different overdrive tables for different scan lines of an image frame through a simple memory arrangement.

"A display system, e.g., an LCD display system, is one of the most essential human-machine-interfaces (HMI) in modern electronic systems. It is therefore a research and development target for electronic manufacturers as to how to provide a display system with lower cost and higher performance.

"A display system comprises several display units arranged as a plurality of scan lines. When displaying a frame of an image signal, display units on a same scan line respectively correspond to pixels of a same horizontal line in the frame. For example, each display unit displays different color levels of a primary color (e.g., red, green or blue) to indicate a component of the three primary colors.

"Based in timing requirements of image display, the display system in sequence updates frames, e.g., updating an f frame to an (f+1) frame. To update a frame, the display system one after another updates the scan lines; that is, the display system updates a first scan line, and a second scan line after having updated the first scan line, and so on. When updating a scan line, a color level C(f), corresponding to one of the display units, of the f frame is updated to a color level C(f+1) of the (f+1) frame according to content of the image data. However, since a response time of the display unit is relatively slower in updating the color levels, it is often that the color level C(f) cannot be updated to C(f+1) in time.

"To enhance the response time of the display unit, an overdrive technique is adopted in driving the display system. With overdriving, the display unit is driven to change the color level from C(f) to (C(f+1)+dC) instead of to C(f+1). For example, when the color level C(f+1) is greater than the color level C(f), the color level dC is predetermined to be greater than 0. Therefore, when the display unit is driven to the higher color level (C(f+1)+dC), the desired color level C(f+1) is more quickly achieved. Similarly, when the color level C(f+1) is smaller than the color level C(f), the color level dC is predetermined to be smaller than 0. Therefore, when the display unit is driven to the lower color level (C(f+1)+dC), the desired color level C(f+1) is more quickly achieved. In actual practice, the value of color level dC is obtained from an overdrive look-up table. For example, the overdrive table determines a positive/negative signal and values of the color level dC according to combinations of the color levels C(f) and C(f+1).

"In many applications, timing requirements for updating different scan lines may vary. In certain applications, although the display system still updates the scan lines one after another when updating a frame, an updated frame is only displayed to viewers when all scan lines in the frame are updated. For example, in some three-dimensional applications, the display system alternately displays left frames and right frames with a display panel in conjunction with shutter glasses. When the display panel displays the left frames, the glasses open up for the left eye and shield the right eye to present the left frames to the left eye; when the display panel displays the right frames, the glasses at the same time open up for the right eye and shield the left eye to present the right frames to the right eye. Accordingly, the user perceives a three-dimensional image.

"However, in the above three-dimensional application, the display system can only present a completely updated frame to the user (with opening and shutting of the glasses) to prevent undesirable effects caused by mixing the left and right frames. That is to say, timing requirements for updating different scan lines are different. When a last scan line of the frame is updated, the entire frame is updated and ready to be presented, and so the last scan line needs a relatively faster response time since it is given a smallest time period from being updated to being presented. In comparison, other scan lines have longer periods from being updated and to being presented and can thus be given with relatively slower response times. For example, a first scan line may have a slowest response time, a second scan line may have a second slowest response time, and so forth. Thus, a last scan line is allowed with a smallest time period and thus needs a fastest response time.

"Therefore, to accommodate applications of different response times for different scan lines, the overdrive technique needs to provide different overdrive tables for the different scan lines."

Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "The invention is directed to an overdrive apparatus and associated method that provides corresponding overdrive tables for a plurality of regions of an image frame by utilizing a simple, low cost, low power consumption, lower layout area and high performance hardware structure to accommodate different response speeds of different scan lines.

"According to an aspect of the present invention, an overdrive apparatus applied to display system is provided for respectively providing corresponding overdrive tables to a plurality of regions in an image frame. The overdrive apparatus comprises an indication unit, a plurality of memories (e.g., DRAMs), and an access circuit. For example, each of the memories stores an overdrive table. The indication unit is for providing an indication signal corresponding to a scan line in the image frame. The access circuit reads a first overdrive table from a first memory and loads a second overdrive table to a second memory according to the indication signal. The first overdrive table and the second overdrive table respectively correspond to a first region and a second region among the regions.

"In one embodiment, the access circuit further reads a fourth overdrive table from a third memory. A calculation circuit receives the first overdrive table and the fourth overdrive table read by the access circuit, and respectively provides a driving value corresponding to each of a plurality of display units in the first region.

"According to another aspect of the present invention, an overdrive method applied to display system is provided for respectively providing corresponding overdrive tables to a plurality of regions in an image frame. The overdrive method comprises: providing an indication signal corresponding to a scan line in the image frame; and reading a first overdrive table from a first memory, and loading a second overdrive table to a second memory according to the indication signal. The first overdrive table and the second overdrive table respectively correspond to a first region and a second region among the regions.

"The above and other aspects of the invention will become better understood with regard to the following detailed description of the preferred but non-limiting embodiments. The following description is made with reference to the accompanying drawings."

For the URL and additional information on this patent, see: Lee, Wei-Kuo; Chiang, Hsin-Chun. Overdrive Apparatus and Associated Method for Display System. U.S. Patent Number 8773412, filed May 10, 2011, and published online on July 8, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8773412.PN.&OS=PN/8773412RS=PN/8773412

Keywords for this news article include: Electronics, MStar Semiconductor Inc..

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Source: Electronics Newsweekly


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