Touch Technology: Infrared (IR) — Grid

Infrared (IR) — Grid

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 photo receptors 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.

Illustration 1: Infrared Touch

Pros and Cons

ProsCons
Functions with scratches and surface wearSolid contaminants, moving liquids or obstructions may cause a false touch and may create dead zones until completely removed
Touch activated by bare finger, gloved hand, or a wide stylusDoes not scale easily (new layout required)
Transmission typically 90 % to 92 %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 two or three resolvable touches

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