HP LP2065 An Overview of Current Display Interfaces - Page 2

Introduction Concerns over image quality, the near-complete replacement of the CRT by LCDs and other new display technologies, and growing concerns over content protection are prompting significant changes in display interface technology. Although PCs will likely continue to use the VGA interface in the short run, long-term, the future is moving to all-digital. Various proposals, including improved analog connectors, hybrid digital-plus-analog approaches, and several all-digital interfaces have been put forth since the early 1990s. One, the Digital Visual Interface (DVI), which is available in both analog plus digital and digital-only forms, has seen reasonable success in higher-end PC products, but has not managed to take the majority of the market from the VGA. Consumer HDTV products have started a migration from the various analog connections to the all-digital High Definition Multimedia Interface (HDMI) - but HDMI shows no signs of adoption in PCs, except for connection to TV products. Most recently, a pair of new PC-oriented standards, the Intel Unified Display Interface (UDI) and the VESA DisplayPort (DP) specification, have received some attention in the press as possible replacements for VGA. The UDI effort is now defunct, never having appeared on any actual hardware, while DisplayPort now appears to be the long-term future for the PC industry, and possibly the converged standard for both PC and CE products. This paper gives an overview of the four leading display interfaces - VGA, DVI, HDMI, and DisplayPort - in the PC industry, and includes a brief history of each, their basic characteristics and pinouts, and provides a comparison of each interface's features and performance. The Future of Display Interfaces Monitor and TV Market Trends The following trends seem likely over the next 3-5 years in the monitor and TV markets. • While there will continue to be a trend to larger-sized monitors, the upper end of this market will not increase significantly in terms of size - the majority of desktop monitors will remain under 30-inch diagonal. Some increase in resolution (pixel formats) will likely occur, but most monitors will maintain the current norms - 1680 x 1050 to 1920 x 1200 resolution for widescreen displays in the 20-inch to 27-inch size range, with the top end of mainstream monitors at about 2560 x 1600 resolution. • The trend in the TV market will be to larger sizes and a greater percentage of widescreen, HDTV-type displays, but in this particular application the pixel formats are constrained by television broadcast standards. The highest-definition format in normal use will remain at 1920 x 1080 pixels. • There will continue to be growing pressure to provide content protection of copyrighted material (meaning the prevention of unauthorized viewing or copying of this material). As it is very difficult to provide adequate protection in the case of analog interfaces, this factor will likely accelerate the adoption of digital connections - and the displacement of their analog counterparts, such as the VGA connector in the PC market. Although content protection is of greatest importance in the consumer products market, the commercial sector may also be affected by this trend. • There is also a growing desire, primarily on the consumer side of the PC market, for better interoperability between PC and digital TV products. Over the long term, this may lead to 2