External Light Noise-Robust Multi-Touch Screen Using Frame Data Differential Method

Camera based multi-touch systems with an infrared (IR) light source have been widely developed and applied to large-size interactive electrical devices. These multi-touch systems are easy to embed in large-sized screens because of their simple structure; however, touch errors due to external IR noise need to be resolved in various applications. An environment with incandescent lamps or sun light has a higher touch error ratio than that with fluorescent lights or LEDs because the aforementioned contain enough IR rays to induce a signal error. To solve this problem, the frame data differential (FDD) method was employed in a multi-touch system along with the rear side diffuse illumination method. The FDD method removed well the IR noise signal without any additional hardware modification to the touch system, and the touch accuracy and sensitivity were dramatically improved in a high IR noise environment compared with the conventional touch sensing method.