The Infrared Touch Screen is a touch frame which is usually installed in front of the display screen. The infrared touch technology depends on the interruption of an infrared light grid. The frame is integrated with a printed circuit board which contains a row of infrared LEDs and photo transistors hidden behind the bezel of the touch frame. Each of the infrared LED has a corresponding photo transistor set on the opposite end, creating a grid of invisible infrared light beams.
The frame shields the electronics from the operating environment while allowing the IR beams to pass through. The Infrared Touch Screen controller sends light pulses sequentially through the LEDs. When a user touches the screen with his finger or other stylus, the infrared light beams will be interrupted. The photo transistors from X and Y axes simultaneously detect the absence of the infrared light and register the X and Y axes coordinates.
The Optical Touch Screen use optical image sensors to continuously scan the touchscreen. When an object comes into contact with the touchscreen, it shows different positions depend on the distance between object and camera. The location of the contact is then calculated by using information from both sensors and mathematical triangulation. Optical touch screens can be operated by both conductive and non-conductive materials. Optical touchscreens support multi-touch events and gestures calculated by algorithms. The size of optical touchscreens is easy to scale, thereby making them well-suited for large TV and interactive blackboards.