Touch Technology: Optical (Camera)

Optical (Camera)

Sensor Materials

Glass substrate, line scanning optical sensors, lighting strips

Principle of Operation

  • Miniature cameras are positioned in the top two corners of the substrate.
  • Illuminated border or reflective borders on the opposing three sides project a uniform field of infrared light slightly above the glass surface.
  • Touch occurs when a finger or object block the light from the cameras.
  • The controller processes the optical information and calculates the X, Y coordinates.

Illustration 1: Optical Touch

Pros and Cons

ProsCons
Functions with scratches and surface wearMoving liquids or solid contaminants may cause false touches or non-function until completely removed
Touch activated by bare finger, gloved finger, or stylusRequires a bezel design to house the edge positioned camera system
ScalableSystem thickness is typically 3.5 mm in addition to the thickness of the glass
Transmission is typically > 90 %Touch occurs slightly above the actual surface
Limited to two resolvable points with two cameras; three or more resolvable points with four cameras

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