How does an infra-red optical touch screen determine the point of contact when touched?

An infra-red optical touch screen determines the point of contact by using a grid of infrared emitters and sensors along the edges of the screen. When a finger touches the screen, it interrupts the beams of infrared light between the emitters and sensors. This interruption creates a distinct pattern of broken beams, allowing the system to calculate the exact coordinates of the touch based on which beams were interrupted. This method of locating the point of contact through a grid coordinate system is efficient and provides accurate positioning of touches on the screen.

Other methods, such as detecting user weight, measuring heat, or utilizing pressure sensors, are not applicable in this context. Infra-red touch screens rely specifically on the interruption of light beams to determine touch points, making the grid coordinate system the clear method for identifying where the screen has been interacted with.