| 摘要 |
<p>A video adapter circuit for adapting analog video signals provided by a personal computer system designed to drive a CRT display monitor into signals appropriate for driving a flat panel display monitor. The video adapter circuit accepts analog video and synchronizing signals in any one of several scanning formats commonly utilized in personal computer systems and automatically detects the scanning format of the signals. An oscillator generates a clock signal that is synchronized with the HSYNC signal generated by the personal computer system. Each of the analog RGB video signals are amplified by a video amplifier and sampled, according to the clock signal, by a digital-to-analog converter. A controller circuit compresses the sampled video signals and stores the compressed data in a dual-port video frame memory at a rate determined by the scanning format. The compressed data is retrieved and decompressed from the video frame memory at a rate determined by the requirements of the flat panel display monitor and converted into a format appropriate for driving the flat panel display monitor. If the received video signals have a resolution that is lower than the resolution provided by the flat panel display monitor, the video adapter circuit automatically expands the image to fill the entire image area of the flat panel display monitor. An on-screen menu provides a user interface for the video adapter circuit, including an ability to adjust the brightness and contrast ratio of the image displayed on the flat panel display monitor by adjusting the dc level and the gain of the video amplifier. In addition, the horizontal and vertical position of the displayed image can be adjusted.</p> |
