Study On Key Problems Of The Touch And Display Driver Integration

Human computer interface has become research hotspot in the field of human computer interaction(HCI).The touch technology is the major way of HCI inputs,and the liquid-crystal display is the major outputs form.The full integration of the touch and display is the only way to solve problems of the relatively independent drive control mode.And the integration will also improve the reliability and simplify the design flow while improving the integration of touch and display.At the same time,it will inevitably bring technical problems such as the interference between them,effective solutions to which will promote the rapid development of HCI.Some key problems of the touch and display driver integration(TDDI)were studied deeply in this paper,and the main research results are introduced as follows:(1)The integration of self-capacitance and mutual-capacitance detection:a 2-in-1 capacitance detection circuit is designed that can be configured to either the self-cap detec-tion mode or the mutual-cap detection mode via the software.Through the proposed design,the circuit has the advantages of high sensitivity and true multi-touch support.The optimized preamplifier of the design reduces the overall system power consumption and has better an-ti-noise performance,both of which are validated by the simulation and experimental studies.The proposed circuit has better performance in the application.(2)Combining both the multiple electrode drive and the IQ demodulation method for touch sensing,a high-precision drive and detection method for projected capacitive touch panel is presented in this paper.In addition,the IQ demodulation method can be used to eliminate completely the phase delays caused by transmission paths.The results indicate that the proposed method can be used to design a high-performance controller chip for capacitive touch-panel detection circuit with a low cost but higher accuracy.(3)For the problem of motion tailing,an optimization over-driving algorithm for liquid-crystal display driver is proposed,in which the structure of voltage looking up table is optimized with the appropriate addressing and traversal algorithm.Then the final result is obtained by the interpolation.Compared with the traditional implementation,the optimization algorithm could reduce the storage space by more than 75%and obtain better display performance.(4)For the integrated anti-noise performance of touch and display driver,a method based on display data statistics and touch capacitance compensation is proposed.The gray-scale value of display unit is obtained through the touch module which is interference by the display part,the gray scale histogram and the compensation coefficient are statisted in real time,and the capacitance correction value is calculated according to the original capacitance value to compensate capacitive touch detection error caused by the change of the liquid crystal capacitance.The simulation and test results show that the proposed algorithm could effectively solve the interference problem of LCD capacitive touch capacitance detection,and realize high precision touch capacitance detection in the touch and display integrated environment.(5)For the integrated scan mode of touch and display driver,a time division and all-drving scan method is proposed.By applying driving signals with same frequency and phase on the row and column lines,the sensing electrode changes synchronously with the two ends of the parasitic capacitances of the row and column lines.So the base capacitance is not taken into account in the final quantization result.The experimental results show that the proposed scheme could reduce the area of the canceling circuit and improve the detection sensitivity.This study belongs to interdisciplinary of microelectronics and information science.And its results have solved some key problems in the HCI integration technology,and improved the convenience and usability of HCI.These technologies could meet the urgent needs of engineering and technical personnel,and raising the level of our country IC designing level,which has a good engineering application prospects and social benefits.