Anti-Ghosting Keyboard Technology

LICENSING Microsoft offers fair and reasonable licensing terms to Manufacturers and Suppliers of stand- alone keyboards, integrated laptop keyboards, and PC OEMs. For licensing information, contact Microsoft Hardware Licensing at [email protected], Subject Line “Anti-Ghosting” For more information and a demo of this technology, please refer to: www.microsoft.com/AppliedSciences/ AntighostingExplained.mspx ANTI-GHOSTING KEYBOARD TECHNOLOGY www.microsoft.com Email: askmsip.com Anti Ghosting keyboard tech.indd 1 3/31/2011 4:20:56 PM technology uses a slightly modifi ed membrane - Membrane keyboard technology revolutionized along with a special, inexpensive readout circuit. the industry by vastly simplifying design. Large HOW Using this technology, true “anti-ghosting” is printed circuit boards (PCB) and individual MICROSOFT LEVERAGED ITS EXPERTISE WHAT practical for even less expensive, mass-market switches were no longer required, and it FOR SIMPLE MEMBRANE-BASED IN MULTI-TOUCH TECHNOLOGY TO keyboards. suddenly became possible to mass produce COMPUTER KEYBOARDS, THERE ARE inexpensive keyboards. NKRO was considered CRAFT A MEMBRANE-BASED KEYBOARD THOUSANDS OF COMBINATIONS impossible, because there was no easy way to WHICH CAN SENSE EACH “KEY” SITE - THAT DO NOT REPORT KEY STROKES add the diodes; and, the world learned to live INDIVIDUALLY INDEPENDENT OF WHAT with inexpensive keyboards - which were really CORRECTLY. only 2-key roll over. OTHER KEYS ARE PRESSED. Not everyone was satisfi ed. In particular, The Microsoft technique adds a printed resistor computer gamers often need to press multiple in series with each “key” site. This can be Microsoft SideWinder X4 gaming keyboard. keys simultaneously; and, gamer forums talk accomplished by printing a layer of carbon- about which vital key combinations work on based ink on one of the membranes. Resistive, select keyboards. Most manufacturers of gaming multi-touch circuitry can then detect the keys individually. Each circuit is inexpensive, requires keyboards are familiar with the complaints WHY low-power, and can function over a wide range MOST KEYBOARDS ARE NOT DESIGNED they receive when someone discovers an important “key” combination which fails to of resistance values. FOR MULTIPLE KEYS TO BE PRESSED Although this is somewhat less than 5% of all work. Serious gamers often spend a great deal Another advantage of this Microsoft technology 3-key combinations, it is a signifi cant annoyance SIMULTANEOUSLY. on their equipment and feed a niche market is that it simplifi es the task of membrane design. for both gamers and fast typists. This is a of very expensive, NKRO gaming keyboards - There is no need to carefully rearrange the This limitation may go undetected by slow, hunt incorporating a diode per key. fundamental limitation of standard membrane and peck typists who carefully release each key matrix, to move bad sets to less problematic keyboard designs. before pressing the next. Faster typists will often locations, because every “key” site can be read independently. In the industry, this problem is generally called press the next key before releasing the earlier “ghosting”, and attempts to alleviate it is called one. In the early days of computing, the ability Thanks to its low-cost/low-power design, “anti-ghosting”. of a keyboard to deal with this “roll over” Microsoft’s Anti-Ghosting Technology is appropri- problem was considered a critical feature. An ate for use in membrane-based keyboards. Now, Microsoft has developed a resistive, multi-touch “N-Key Roll-Over” device (NKRO) would allow gamers and everyday typists can be free from technology which allows a membrane keyboard any number of keys to be pressed simultane- “ghosting” and “roll over” issues. to accurately report and see very large numbers ously - while still reporting them correctly - and of arbitrary keys pressed simultaneously. This early keyboards typically used individual switches technology is showcased in the Microsoft soldered to a large PCB. The “NKRO” feature SideWinder X4 gaming keyboard. Unlike tradi- could be achieved by placing a diode in series tional solutions, which require a large printed with each key – a relatively minor expense circuit board and a diode (per key), Microsoft’s compared with all of the other parts. Anti Ghosting keyboard tech.indd 2 3/31/2011 4:20:59 PM.

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