Design Of Capacitive Touch Panel System Based On FPGA

In recent years,the special display equipment is required to be developed indigenously.It is a challenge as well as an opportunity for domestic related fields.At present,most of consoles of military equipment are still in form of key operations,which is difficult to support functions such as multi-finger operation and multi-person simultaneous control.Therefore,it is necessary to develop touch panel for military display instruments.As an important implementation for human-computer interaction,touch panel have huge development prospects.Among them,the capacitive touch panels have received increasing attention due to its advantages such as fast response speed,long service life and high light transmittance.However,the working environment of military large-size touch panels is extreme so that the requirements for product reliability are strict.The future design must take into account performance indicators such as touch sensitivity,accuracy,and anti-interference.In this paper,oriented to the actual needs of special display equipment,a capacitive touch panel control circuit was designed for large-size touch panels of military aircraft.This design supports multi-touch and improves anti-interference ability,in the meanwhile,the indicators of this design such as sensitivity,reporting rate and refresh rate are expected to reach the mainstream imported chips.The main work includes six aspects: First,the sensor structure of the touch panel is studied through modeling and simulation,and the influence of ITO electrode size and structure on improving sensitivity is summarized;Second,according to the large number of channels of the large-size touch panel,the serial-parallel receiving circuit is adopted to greatly increase the signal transmission rate,while decreasing the economic cost and the power consumption;Third,the charge transfer method circuit is employed to measure the change of tiny capacitance,which improves the accuracy of capacitance detection;Fourth,the digital filtering algorithm and dynamic reference value are designed to reduce the interference of the environment;Fifth,a coordinate calculation method with offset correction is utilized to get high accuracy in touching positioning;Sixth,the experimental platform is built to complete the function debugging,and an excitation adjustment design was adopted to realize the electromagnetic compatibility of the product to meet the air force test requirements.This article has completed the software and hardware design of each part of the system.Verilog hardware description language was used to complete the code design of each module,and the functional debugging test was completed.The results show that the touch accuracy of the system meets industry requirements,and the electromagnetic compatibility meets the air force test requirements in the special display field,hoping to provide a reference for the research and development work of related industries.