We have developed Shared Column-Line Driving (SCLD) method, by which the number of data driver LSIs is reduced to a half of conventional ones without doubling the number of gate lines. This paper shows the concept and system configuration of the SCLD method which can be applied for high pixel density and low cost TFT-LCDs. . IntroductionThese days active matrix liquid crystal displays(AMLCDs) have been widely used for many applications. And its resolution is becoming higher. In other words, pixel pitch is becoming smaller. However, tape carrier package(TCP) and tape automated bonding(TAP) techniques do not satisfy the small and fine pitch characteristics for the small size and high resolution applications such as cellular phones and personal digital equipments. Therefore, there are lots of researches about package of AMLCD such as chip on glass(COG) to overcome the pitch limitation of TCP and TAP. And also, there was a research to increase the resolution of AMLCD without change of package types and bonding technologies. It was the half-column-line driving method which was proposed for reducing the power consumption and module cost, originally[1].This driving method can reduce the number of column driver LSIs by which each column line drives both pixels on its right and left sides and reduce the power consumption of column drivers in the module to a half but its panel has twice as many gate lines as those of a conventional one. These doubled gate lines decrease the aperture ratio and the rearranged of video data as zig-zag sequence increase the complexity of controller and digital data rate between frame memory and controller and also slightly increase the module cost because of double numbered gate driver.And two pixel are driven in one horizontal line time, it has not enough line time to drive the high resolution TFT-LCDs. To eliminate this problem, we propose a Shared Column-Line Driving(SCLD) method. In this paper, we describe the concept, and operation principle of the proposed pixel structure, and architectures and configurations of scan driver and data driver for implementation of the proposed SCLD method. Pixel Structure of SCLD MethodThe pixel array for the proposed SCLD method is shown in Fig. 1. The proposed SCLD method can reduce the number of column lines by half of the conventional LCD panel without increasing the number of gate lines. One column line is connected to the both side pixels on its right and left sides. Two pixel TFTs in the right side of the column line connected to N-th gate line. In the left side of the column line, one pixel TFT is connected to the N-th gate line and the other is connected to (N+1)-th gate line. And two series connected TFTs of right pixel, those gate are connected N-G1 G2 G3 G4 D1 D2 Figure 1. The pixel structure of the proposed shared columnline driving method. G2 G3 G1 1st H 2nd H a b Vdd gnd positive video range negative video range D1 Vcom Figure 2. The waveform of the scan pulse and driving sequence of the proposed SCLD method.th gate line, are reduced to one T...
A 10-bit gray-scale source driver using a resistor-resistor-string digital-to-analog converter (RR-DAC) is proposed for a TFT-LCD source driver. The 10-bit RR-DAC consists of an 8-bit resistorstring DAC and a two-bit resistor-string DAC without an intermediate unity-gain buffer to isolate the parallel-connected resistor string. The output deviation of the proposed source driver is less than ±3 mV. The chip area of the proposed 10-bit source driver with an RR-DAC is increased to 29% of that of an 8-bit source driver.
A 10bit gray scale source driver using resistor-resistor-string digital to analog converter(RR-DAC) is proposed for small chip area TFT-LCD source driver. The 10bit RR-DAC consists of 8bit resistor-string DAC and 2bit resistor-string DAC without intermediate unity gain buffer to isolate parallel-connected resistor-string. The chip area of proposed 10bit source driver with RR-DAC is increased 29% of that of the 8bit source driver.
A data driver using the triple charge sharing method and an OP-AMP with the low-quiescent current have been proposed for low-power TFT-LCDs. The triple charge sharing method can reduce the AC power consumption of TFT-LCDs to 1/3 of that of conventional ones. The measured quiescent current of the proposed OP-AMP is 5µA at VDD=5V.
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