The Design of Light Pipe with Microstructures for Touch Screen

Touch screen has a very wide range of applications.Most of them are used in public information inquiries,for instance,service inquiries in telecommunication bureau,tax bureau,bank system,electric department … Touch screen can also be used for entertainment and virtual reality applications too.Traditionally,touch screen was composed of pairs of infrared LED and correspondent receivers which were all installed in the screen frame.Arrays of LED were set in the adjacent sides of the frame of an infrared touch screen while arrays of the infrared receivers were fixed in each opposite side,so that the infrared detecting network was formed.While the infrared touch screen has some technical limitations nowadays such as the low resolution,limitations of touching methods and fault response due to environmental disturbances.The plastic material has a relatively high absorption rate for infrared light,which greatly limits the size of the touch screen.Our design use laser diode as source and change the traditional inner structure of touch screen.by using a light pipe with microstructures.The geometric parameters of the light pipe and the microstructures were obtained through equation solving.Simulation results prove that the design method for touch screen proposed in this paper could achieve high resolution ratio(R.R.) and large size of touch screen.