Adaptive charge sharing method for liquid crystal displays with lower power consumption

Seung-Ryeol Kim,Seung-Woo Lee,Jong-Man Kim,Minkoo Kim

doi:10.1117/1.oe.54.5.053111

Abstract

This paper proposes an adaptive charge sharing (ACS) method for reducing power consumption in liquid crystal displays (LCDs). Our ACS method involves calculating the power consumption of all data lines assuming the charge is shared and analyzing the analog characteristics of the data transitions. With conventional CS, charge is shared between data lines only when the polarities of data signals change. Our ACS method selectively shares charge even when no polarity change occurs, but only if CS provides an overall reduction in power consumption. To compare the performance of ACS and conventional CS, we applied the ACS method to common inversion methods, namely, column, two-dot, and Z inversion. Our simulation results demonstrate that the ACS method can effectively reduce power consumption, especially with the column and Z inversion methods. The average power consumption of the ACS method with column and Z inversion was 87.7% and 84.7%, respectively, of the conventional CS power consumption.

Highlights

In order to verify the effectiveness of our adaptive charge sharing (ACS) method, we designed MATLAB simulations to analyze the effects on power consumption when two-dot, column, and Z inversion methods are used
The actual power consumption is determined by voltage transitions, not by digital data, we need to calculate the power consumption using analog voltages corresponding to the image data
We proposed an ACS method for reducing power consumption in liquid crystal displays (LCDs) driven with two-dot, column, and Z inversion methods

Summary

Introduction

Power consumption in liquid crystal displays (LCDs) is currently the subject of intensive research.[1,2,3,4,5,6,7] To achieve lower power consumption with higher image quality in LCDs, various techniques have been studied, including backlight dimming technologies,[8,9,10,11,12,13,14,15] inversion methods,[16,17,18] and charge sharing (CS) methods.[19,20,21,22,23,24,25] Column inversion provides very low power consumption because only one polarity change occurs per frame. In this way, Z inversion consumes lower power than dot inversion. We propose an adaptive charge sharing (ACS) method intended to reduce power consumption when two-dot, column, or Z inversion is used. By considering the various types of analog data transitions, the ACS method selectively shares charge between data lines only when CS provides an overall reduction in power consumption.

Basic Principle of Charge Sharing

Adaptive Charge Sharing Method

Results and Discussion

Conclusion