Computer graphics processing and selective visual display system – Computer graphics processing
Reexamination Certificate
1998-10-31
2001-11-27
Vo, Cliff N. (Department: 2772)
Computer graphics processing and selective visual display system
Computer graphics processing
C345S440000
Reexamination Certificate
active
06323854
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention pertains to video monitor systems, and more particular to a multi-tile, auto-configuring display system using a serial link.
2. Description of the Related Art
Video monitor systems are well known to the computer field. Originally adaptations of the television, the video monitor originally was a fairly straightforward device. It typically provided a text field of 80×24 characters, with data being received over a serial link and stored as ASCII or other types of codes. A controller would then display those characters on the video screen.
With graphical computing, however, the demands upon monitors increased. Personal computers were implemented with graphics controllers that provided a digital signal suitable for driving the monitor. The graphics controller board typically included video memory for mapping the image to be displayed and a cathode ray tube controller (CRTC) that repetitively read the video memory to provide appropriate digital signals for transmission to the monitor. With the early controllers, the data for each pixel was transmitted as a digital value to the monitor itself. This value was then passed through a digital-to-analog converter, so that an appropriate color was displayed for that pixel. Later, analog signals for each pixel of the image were instead transmitted, such as by using a video graphics adapter (VGA) controller.
With the increasing resolution of monitors, however, the speed of operation of the video controller and the CRTC and the bandwidth of the signal between the video controller and the monitor have entered into play as limiting factors. For example, 1280×1024 resolution addressability monitor running at a 70 Hz refresh rate requires a bus bandwidth of 91.75 MHz pixel data rate. Those in the art will understand that resolution and addressability are often used as interchangeable terms. Increasing the display resolution necessarily results in a higher required data rate.
Further, modern systems sometimes employ multiple monitors for a single computer. Such configurations are sometimes used in concert to display a single image. Generally, however, the physical arrangement of the monitors must be manually configured into the display controller driver. Further, each monitor typically has a corresponding display controller in the computer system.
SUMMARY OF THE INVENTION
In a system implemented according to the invention, a plurality of monitors are implemented which incorporate their own CRTC. Rather than receiving a standard video signal, they are connected to a video controller via a high speed serial bus, over which the video controller transmits only the changes in the video image to be displayed. Those changes are compressed, such as by using run length encoding. Further, they can be converted from RGB to YUV format, and transmitted in YUV format.
Within each of the monitors, circuitry receives that changed data, parses out the portions of that data necessary for display on that particular monitor, and stores a video image in an internal frame buffer. The CRTC then repeatedly scans the frame buffer at high speed, transmitting a standard video signal to a video display engine, which could be a variety of types, including a cathode ray tube or a projection-based system.
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Knox Richard M.
Welker Mark W.
Duke University
Fleshner & Kim LLP
Vo Cliff N.
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