Touch Technology: SAW

Surface Acoustic Wave (SAW)

Sensor Materials

Glass, piezoelectric transducers

Principle of Operation

  • Piezoelectric transmitters on the sensor generate acoustic waves on the surface of the glass substrate on alternating X-axis and Y-axis patterns.
  • The acoustic waves are reflected by a pattern of edge ridges directing the energy to piezoelectric receivers.
  • A touch to the surface of the sensor causes attenuation to a portion of the wave corresponding to touch position.
  • Touch location is based on the time delay from the transmitted pulse to the center of the attenuation area of the wave.

Illustration 1: Surface Acoustic Wave (SAW)

Pros and Cons

ProsCons
Touch activated by bare finger, some gloves, or soft conductive stylusMoving liquids or solid particles of contaminants may cause false touches or areas without touch function until they are completely removed
Light transmission typically 92 %Dirt and water seal can be difficult
Typically wide border
Limited to 1 resolvable points

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