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Published on Nov 29, 2010
Surface Acoustic Wave Touch ScreensThe structure of touch screens based on surface acoustic waves (SAW) is quite complicated. A screen of this type is in fact a glass panel with piezoelectric radiators placed at the corners which create ultrasonic vibrations. Deflectors are located on the edges of the panel. With their help acoustic waves are spread over the whole surface of the screen and are transmitted to piezoelectric detectors.When the screen is touched by fingers part of the acoustic wave energy is absorbed. The changes are registered by detectors which send an electric signal to the control element. The control element in its turn determines the position of a contact point. These types of screens malfunction in case of any vibrations or acoustic noises. It is their main disadvantage. Apart from that SAW touch screens are much less precise than capacitive touch screens. They are not suitable for typing texts or drawing. Still this technology has several advantages. First of all, you can track force of pressure along with coordinates of the contact point.Secondly, despite their quite complicated design, SAW touch screens are durable.Thirdly, these devices are highly transparent. Light passes through glass which doesn't have any conductive coating. In some cases so as to avoid glare no glass is used at all, and deflectors, detectors and radiators are attached to the display. SAW touch screens are mostly used in reference systems and educational institutions.