Network displays take on VGA/DVI multi-monitor limitations

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The display industry has an interesting new connectivity method that uses network display technology to connect monitors to PCs, network displays, writes Jason Slaughter of DisplayLink.Since the development of the PC, graphics cards with VGA-like connectors have been used as the primary means of connecting displays to host computers. Now the display industry has an interesting new connectivity method that uses network display technology to connect monitors to PCs.
Network displays connect over standard network interfaces - USB 2.0, Ethernet, Wi-Fi, Wireless UWB, WiMedia - bringing improved flexibility and unparalleled ease-of-use to multi-monitor computing.Traditional display connector technology requires a dedicated graphics card for each display, unless a costly multi-headed graphics card is used. Small form factor and notebook displays are even more limited in their display expansion possibilities due to space constraints. The cost and complexity of today's display connection technology has inhibited the uptake of multi-monitor computing, despite the proven productivity benefits[1] of using multiple monitors.
The most promising possibility for bridging this complexity gap comes from display connections over personal area networks (PANs). PAN configurations connect displays using point-to-point or close-range network technologies such as USB, Wireless USB and WiMedia.Over recent years, ground breaking technology has been developed which is driving a new market for secondary PC displays - multiple monitors can now be attached to a PC or notebook via a standard USB 2.0 connection, and can even by 'daisy chained' together through USB 2.0 hubs. Each of these displays is able to extend the Windows desktop over six monitors for the ultimate multi-monitor computing experience. The technology is also cost-effective to deploy - especially in corporate environments - making it a key enabler for the growing secondary display market and allowing multiple monitors to be added faster and more economically, without the need for additional graphics cards. Market momentumThe network display market has recently gained momentum with the debut of second-generation USB 2.0 products, with DVI-like image quality and DVD-quality video playback. This core technology has fuelled the development of new products including USB-to-VGA adapters, universal notebook docking stations, and even USB-connected monitors like the Samsung UbiSync 940UX or LG L206WU.
The market is poised for an array of new capabilities, including wireless connectivity through Wireless USB using the same basic architecture.Second-generation network display technology is set to overcome the significant limitations of its predecessors. Until recently, Wireless USB or USB 2.0 connected displays were marred by slow screen responsiveness to mouse and keyboard input, poor image quality, and no support for DVD video playback. Resolutions were often limited to 800×600 with only 16-bit colour, resulting in inferior quality and user experience compared to standard VGA monitors.Key considerationsWhen considering a second-generation USB display solution there are three key factors - display quality, interactivity, and ease-of-use. Firstly, the optimal solution should support smooth, full-frame rate DVD-quality movies without ghosting or jittering playback, offering resolution and colour depth comparable to a high quality DVI-connected display - crisp graphics at 1680×1050 resolution (22″ LCDs) and support for 32-bit true colour are a must.
Secondly, the response time should be nearly instantaneous - more than 20 milliseconds will be noticeable by the user. Without adequate real-time response, mouse movement and data input become cumbersome and impact on productivity. Finally, the quick hot-plugging and unplugging of displays via simple USB cables is crucial. While the VGA cable is relatively simple, there is no built-in intelligence - USB was designed to support hot-plugging and easy connectivity from the start. A USB display can automatically configure itself to the best resolution of the screen when a new display is connected. When a device is unplugged, the windows on that screen will return to the primary display, for instance when a notebook PC is undocked. Most importantly, when plugging in a previously-used USB monitor, the location of the display can return to its last point of use. Such intelligence allows for a significantly improved user experience when moving locations, hot-desking, or docking and undocking a notebook PC.
Technical challenges While network displays undeniably make it easier to add an additional monitor to a PC, there are technical challenges to overcome. A USB 2.0 connection has a maximum throughput of 480Mbps, and while Wireless USB promises to match this, its connections today only range from 80Mbps to 250Mbps. More importantly, the latency of these connections means that using a traditional graphics chip designed for a low-latency PCI or PCI-Express bus will incur unacceptable delays that can render a network display product unusable. While network connectivity is constantly improving, there will always be the challenge of meeting the high resolution and performance requirements of today's LCD displays.These problems can be solved by using a combination of clever compression and by splitting the way the graphics are processed. Instead of putting a heavy-weight graphics processing unit (GPU) at the end of the bus (or network connection), second-generation network display technology has been developed that processes all graphical commands on the host CPU (and GPU, if available), taking advantage of any content-dependant optimisations possible.
An adaptive compression protocol is then applied to the graphical data, changing the compression parameters based on the available CPU or USB bandwidth and allowing very low -latency transfers to the network display chip. A lightweight decoder chip can then be embedded into the adapter, monitor, or docking station, to decompress the data and display it via VGA, DVI, HDMI, or directly to an LCD. The result is a high performance connection over USB or Wireless USB that is nearly indistinguishable to a typical DVI connected display for the vast majority of tasks.Breaking freeNetwork display technology breaks the 1:1 computer-to-display barrier imposed by traditional display technology, while also meeting the important performance and image quality metrics. USB connectors allow for an easier, cheaper, and quicker alternative for multiple monitor connections, with Wireless USB providing a future path to wireless over the same basic architecture.
As the industry evolves and display connectivity in data-intensive applications becomes essential, network display solutions offer a first-rate option that save space and cost, while maintaining great performance.By Jason Slaughter, Director of Marketing, DisplayLink[1] Microsoft Research shows a consistent nine percent productivity increase by adding a second display, with up to a 50 percent increase in productivity for tasks such as cutting and pasting.

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