An infrared touch screen is a touch frame assembly typically installed in front of the display screen. Its core working principle relies on the interruption detection of an infrared light grid: the touch frame integrates a printed circuit board (PCB), with a row of infrared LEDs (light-emitting diodes) and phototransistors hidden inside the bezel. Each infrared LED is paired with a corresponding phototransistor on the opposite end, forming an invisible grid of infrared light beams.
The touch frame protects internal electronics from the operating environment while enabling IR beams to pass through. The infrared touch screen controller sequentially transmits light pulses through the infrared LEDs. When a user touches the screen with a finger or other stylus, the infrared light beams are interrupted. Phototransistors on the X and Y axes simultaneously detect the absence of infrared light and register the X/Y axis coordinates of the touch point.
The optical touch screen uses optical image sensors to continuously scan the screen. When an object comes into contact with the touchscreen, it displays different positional information depending on the distance between the object and the camera. The controller then accurately calculates the touch point coordinates by integrating data collected from both sensors and applying mathematical triangulation. Optical touch screens support operation with both conductive and non-conductive materials, enable multi-touch operations and gesture recognition via algorithms, and are easy to scale in size—making them ideal for large-size TVs and interactive blackboards.
