Touchscreen uses near-field imaging

Sept. 16, 2004
Touch-screen technology has long been used for indoor applications, but strong sunlight and extreme weather is too hard on the electronics.

Engineers at 3M Touch Systems, Methuen, Mass. (, have developed a new integrated touch screen, the Microtouch Near Field Imaging screen, that features solar-reflecting film sandwiched between two glass layers. The nonmetallic film reflects rather than absorbs infrared solar energy while letting visible light pass through, thus keeping the electronics and LCD inside cooler and less prone to failures. The glass layers include a top, protective cover, and the bottom sensor plate. The sensor plate has a patterned coating of transparent metal oxide. An ac signal applied to the conductive coating creates an electrostatic field on the screen surface. A finger or conductive stylus touching the screen surface disturbs the electrostatic field, and the touch and its location are registered. The screens work even if users wear gloves, or have moisture, gels, and other contaminants on their hands. The screen's glass construction lets it operate despite scratches, pits, and other surface damage from abrasives, chemicals, and vandals.

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