Design Of High Resolution Infrared Touch Controller

In recent years,the multi-touch screen technology has played a very important role in the human-computer interaction technology.The touch screens always have the disadvantages of high-cost or complicated structure.Or they are easily interfered by temperature and the operating environment.It is necessary to reduce the cost,simplify the structure and improve the recognition accuracy of multi-touch screen.In this paper,a FPGA-based logic control method for contact recognition is presented.And an infrared touch screen is designed.The control method is implemented on this touch screen.The main works of this paper are described as follows:1.Complete the simulation of the radiation curve of infrared LED using “lighttools”,get the blocked radiation curve and no-block radiation curve separately.Complete the measurement of the LED radiation curve,and contrast the result of measurement with the result of the simulation.Verify the feasibility of system principle.Determine the calculation method of the touch-point coordination.2.An LED-based infrared touch screen is designed and implemented with STM32 and FPGA as the core parts.This touch screen has a two axis structure in two dimensional.The FPGA is in charge of the control of channel selection both in emitting parts and receiving parts.The STM32 calculates the coordinate of the touch point and sends up the coordinate to the PC.3.The software system of FPGA is designed.FPGA receives the command sent by STM32 using SPI protocol.According the result of address check,the working state is determined.And the control of channel selection is completed according to the result of decoding.In this way,the emitting and receiving channels can be selected easily.4.The speed and accuracy of the touch screen are analyzed.The results of experiment show the accuracy can break the limit of LED size,reach the sub-pixel level.