Study Of The Driving Circuits For TFT-LCD

In the thesis, the design is performed for the driving circuit of a 16.1?SXGA TFT-LCD. The development of TFT-LCD, due to the increasing of information content and the expansion of display area, result in the problems of flicker, crosstalk, shorten time of charging pixels, the increasing of electromagnetic interference and power consumption. These problems are analyzed, calculated and experimented from the point of the driving circuits and solved them successfully [ The problems are solved such as shorten time of charging pixels, crosstalk by a dot inversion driving method. The limit of TFT array parameters is also widened. The driving frequency is reduced from 112MHz to 56MHz by a double (odd and even) data lines input method in order to reduce EMI. The power dissipation is reduced 50% by a charge-share method. At the same time. scan-drivinn waveform is calculated and experimented for a 16.1 inch SXGA TFT-LCD with a capacitively coupled driving mode. The use of the negative pulse of the third voltage level (-8V) solves the problem of flicker result from the voltage jump( A Vp) so that DC component is minimized. The double-pulse scanning driving method solves the problem of short time of charging pixels. Meanwhile, the relationships between gate voltage and the error of charging pixels and between the size of TFT and the error of voltage jump( A Vp) are calculated in the two case of single and double pulses. It is proved clearly that double pulses scanning is better than single pulse, the errors are reduced from 0.25V to 0.05V and from 0. IV to 0.05 V respectively. Thus, they provide important foundations for array design of high-quality TFT-LCD. The problem of gray-level Gamma correction in LCD is solved. By considering non-linear of human vision and non-linear of LC electro-optical characteristics. Gamma corrections are solved in driving circuits of the line inversion and the dot inversion methods, respectively, their final target values and practical values are basically corresponding. Therefore, conditions of developing new products are created for JILIN Color TFT-LCD Corporation. In the final part of thesis, the peripheral integrated driving circuits of (640 >( 3) X 400 TFT-LCD is designed by simulation. Output voltage of scan driving circuit is 20V, operating frequency is more than 24KHz of design requirements. Data driving circuit of the divided matrix switches is put forward and the TFT size of divided matrix switches are designed. The curves of output characteristics show that the requirements of four gray-level LCD are meet. And the output TFTs parameters are optimized by an Elmore delay model. Designing requests of p-Si peripheral integrated driving circuits on TFT-LCD, a project funded by 揟he Ninth Five-year Plan of Chinese Academy of Sciences? are realized.