Design Of Ultra Widescreen Interactive Whiteboard Based Infrared And Ultrasonic Location

Interactive Whiteboard is a kind of interactive electronic products, which Combined with wide screen display technology and the electronic whiteboard control technology, and it can realize writing, projection, computer operation, record writing. It is widely applied to teaching, meeting, military exercise, and other fields.This paper proposes a whole hardware and software scheme of an ultra widescreen interactive whiteboard using dual receiver positioning technique, which can carry out precise positioning in the traditional teaching blackboard(4m*1.5m)and writing on ultra wide screen. Electronic whiteboard hardware circuit system design, it mainly including signal transmission module, the signal receiving module, main controller module.The low power design of signal transmission module can send40KHZ frequency ultrasonic infrared signals. The signal receiving module can complete the sampling signal acquisition, amplification and filtering operation. At the same time, for improving the ranging precision and anti-jamming signal, this paper uses combining hardware AGC gain automatic control circuit and software look-up table to receive Stable ultrasonic signal amplitude, A temperature compensation circuit is also designed to improve the ranging precision.The main controller module to complete the data signal processing and the data package convenient by pull out plug USB HID way to transfer to the PC.For the wide-screen projection area is larger, it is necessary to be more accurate to locate the coordinate transformation algorithm, in first, computer software need to design any3points to determine the area of computer coordinates on widescreen, then joining the multi-point calibration algorithm based on affine transformation method to ensure the accuracy of positioning.we put forward a linear fusion method to solve the problem of coordinate selection in fusion zone. PC application receives virtual coordinate datum from the left and right sides,the linear fusion respectively take the coordinate data to create a new virtual coordinate values according to certain proportion, which determin the only virtual sampling coordinate and virtual ideal coordinate mapping relationship. Experimental results show that the system has realized the widescreen writing handwriting real-time tracking, and is suitable for use on different material, its versatility is strong, high reliability, meeting the requirements of the using of electronic whiteboard.