Diagram: 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.

Advantages

  • Functions with scratches and surface wear
  • Touch activated by bare finger, gloved finger, or stylus
  • Scalable
  • Transmission is typically >90%

Disadvantages

  • Moving liquids or solid contaminants may cause false touches or non-function until completely removed
  • Requires a bezel design to house the edge positioned camera system
  • System thickness is typically 3.5 mm in addition to the thickness of the glass
  • Touch occurs slightly above the actual surface
  • Limited to 2 resolvable points with 2 cameras; 3 or more resolvable points with 4 cameras