The Research And Development Of Optical Touch Screen

As the development of the society, improving human-computer interaction is a important thing. There are many way to realize human-computer interaction, and touch is the most common and easy one. This paper completes the design of the optical touch screen that supports the multi-touch; include the design of hardware and software.This paper put forward the idea that use four camera to local one or two touch point which is different from the normal optical touch screen that commercially available on the market. The idea not only can efficiently solve the problem that the camera been all-covered, but also can improve the stability of the touch screen system.Base on the analysis of the practical situation, we choose the hardware that have low cost and high reliable. At the same time we get the resolution of the system and the maximum error base on theory through calculation. And design the technological process of the system.According to design of the system, we set up the right parameter on the FW0513camera module, make the FW0513camera module can capture the picture at a high rate that go to97frame/s. The return rate is100Hz level. This rate reaches the standard of the commercially available mouse. After optimizing the ARM9chip, we can make the I2C transmit speed goes to400kbit/s. And we can use ARM32master control chip to send order to ARM9chip to have a serial operation on it.We implement the location of one or two touch point algorithm on the ARM32master control chip. The algorithm is determine the location of the touch point through the step point that from the camera modules. The location algorithm use the data from the two cameras to make a preliminary judgment, and use other two camera to eliminate the ghost point。We use the algorithm to demarcate the camera to make the calculated touch point have a higher precision. At last we will make the test to make sure the device can meet the requirement.