Design And Implementation On Infrared Touch-Screen Of High Reliability

Today touch-screen is widely used. Technology improvements in industrial control and even aviation technology are in urgent need to facilitate human-computer interaction. Compared with the popular types of touch-screens, infrared touch-screen satisfies the requirements of particular working environment best. Investigations on 6 aspects are carried out to testify the function of the touch-screen, namely:high resolution, wide working temperature range, good shock resistance, long service life, anti-glare interference, and multi-touch supporting. Through both software and hardware designing, large-sized infrared touch-screen with full function is developed.Traditional infrared touch-screen has some disadvantages, which mainly concentrate on low resolution and poor resistance to light interference. By laying infrared tubes in double rows, the physical resolution of the touch-screen is improved. At the same time, the A/D converter is used to improve the logical resolution by quantifying the voltage signal. In this way, resolution of the touch-screen in this thesis has been achieved 4096 X 4096. Clamping circuit is used in the signal acquisition part to filter the interference of the ambient light. By laying infrared emitter and receiver in both left side and right side, the problem of glare interference can be solved as light travels straight.In the aspect of software processing, the methods of limiting filter and moving average filter are combined to rule out the interference signal, which turns out to be effective. Accordingly, the function of line-drawing and handwriting are enhanced by improving the accuracy of the data. In realizing the multi-touch function, infrared tubes controlled by software are used to scan obliquely so as to determine the distance between the two points, with which we can eliminate pseudo points. At the same time, the design of the mobile tracking algorithm can judge the location of the moving points, with which line-drawing delay and disconnection can be avoided.The results of all the tests mentioned above——normal temperature test, high and low temperature test, vibration test and the glare test, show that the infrared touch-screen designed in this thesis meets the demands of the environment. It also achieves the performance of high reliability and acquires high engineering application value.