Infra-Red Technology

Often referred to simply as "IR", infra-red touch sensor technology operates on the principle of the touch interrupting light. Light emitting diodes or LED's are placed on one edge of the "X" and one edge of the "Y" axes on the display. A series of photoreceptors are placed opposite these LED's, and the result is a grid of X-Y light paths above the surface of the display. The touch controller constantly scans this X-Y grid. Touch within the grid blocks the light path, and the controller triangulates that interruption and identifies the point of touch.

A glass or acrylic substrate is typically placed above the display surface and the LED's and photoreceptors are arrayed around and housed within the interior of a mechanical frame or bezel. This bezel typically replaces the manufacturer's original bezel. Infra-Red is a touch sensor technology that requires "frame-based" construction.

 

Infra-Red: Key Points

• high opitcal clarity (depending upon substrate quality)
• use of finger, gloved hand or wide stylus touch
• functions with scratches or surface wear
• accuracy limited by LED and receptor placement
• narrow stylus not permitted due to width of physical grid path fixed by LED and receptor placement
• obstructions, liquids or contaminants can reduce or eliminate function until removed, including "false" or inaccurate touch
• LED's and photoreceptors exposed to contaminents
• touch occurs slightly above the surface which can result in unintended touch response, or "touch parallax"
• requires mechanical frame or bezel
• LEDs, photoreceptors introduce "wear-out" potential to touch mechanism