Diagram: Infrared Wave Guide (IR)

Infrared (Grid) (IR)

Sensor Materials

Glass or acrylic substrate, wrap-around-bezel frame, LED matrix

Principle of Operation

  • LEDs create a grid of X and Y infrared light beams projected above the display and are detected by photoreceptors on the opposite edge.
  • Touch occurs when a finger or stylus blocks the beam from reaching light detectors.
  • Controller’s constant X and Y axis scanning detects blocked light detectors and triangulates touch location.

Advantages

  • Functions with scratches and surface wear
  • Touch activated by bare finger, gloved hand, or a wide stylus
  • Transmission typically 90% to 92%

Disadvantages

  • Solid contaminants, moving liquids or obstructions may cause a false touch and may create dead zones until completely removed
  • Does not scale easily (new layout required)
  • Beam spacing limits accuracy and stylus width
  • Touch occurs slightly above the actual surface resulting in possible touch parallax or an unintended touch response
  • Requires a bezel design to house the LEDs and detectors
  • Limited to 2 or 3 resolvable touches