Patent ID: 7477223
Filing Date: 2009-01-13
Classification: G09G

Abstract:
1. A method of driving an active-matrix liquid-crystal display device including a liquid-crystal panel comprising: a pair of substrates, at least one of which is a transparent substrate; a plurality of data lines, which are each extended in a row direction on a specific one of said substrates and are arranged in a column direction perpendicularly intersecting said row direction; a plurality of gate lines, which are each extended in said column direction and are arranged in said row direction; an active device connected at an intersection of each of said data lines and each of said gate lines; a pixel electrode driven by said active device; an opposite electrode provided on said specific substrate or the other one of said substrates as an electrode sandwiching a liquid-crystal layer between said opposite electrode and said pixel electrode; and a storage capacitor connected in parallel to said liquid-crystal layer; wherein: a frame period of an image displayed on said liquid-crystal panel is divided into a scanning period and a hold period longer than said scanning period; in said scanning period, image data of an amount corresponding to a frame is written into said liquid-crystal panel; in said hold period following said scanning period, an off state is sustained; an electric potential appearing on a positive-polarity data line in said hold period is increased to a level higher than an electric potential appearing on said opposite electrode where said positive-polarity data line is defined as said data line, on which an electric potential appears at a level higher than an electric potential appearing on said opposite electrode when an electric potential appearing on said gate line changes from an on-state level to an off-state level in said scanning period; and an electric potential appearing on a negative-polarity data line in said hold period is decreased to a level lower than said electric potential appearing on said opposite electrode where said negative-polarity data line is defined as said data line provided on a row adjacent to said positive-polarity data line as said data line, on which an electric potential appears at a level lower than an electric potential appearing on said opposite electrode when an electric potential appearing on said gate line changes from an on-state level to an off-state level in said scanning period, wherein said electric potential Vsig appearing on said positive-polarity data line in said hold period has a value in a range expressed in an MKSA unit system by relation (1) as follow: where symbol τ denotes a quantity expressed by the following equation: symbol Vopt denotes an electric potential expressed by Eq. (2) as follows: symbol Roff denotes a resistance [Ω] exhibited by said active device when said active device is put in an off state; symbol R1 denotes a resistance [Ω] exhibited by said liquid-crystal layer sandwiched by said pixel electrodes and said opposite electrode as a resistance expessed by the following equation: symbol S denotes the area [m symbol d denotes the thickness [m] of said liquid-crystal layer; symbol ρlc denotes the resistivity [Ωm] of a liquid crystal composing said liquid-crystal layer; symbol Vcom denotes said electric potential [V] appearing on said opposite electrode; symbol f denotes a frame frequency [Hz]; symbol Cl denotes the capacitance [F] of said liquid crystal of said liquid-crystal layer; symbol Cstg denotes the capacitance [F] of said storage capacitor; symbol Csd denotes the capacitance [F] of a parasitic capacitor existing between said pixel electrode and said data line for said pixel electrode; symbol Vfst denotes an electric potential [V] appearing on said pixel electrode right after an on-state period in said frame period of said pixel; symbol ΔVc(f) denotes a change [V] in critical electric potential for said frame frequency f and said electric potential Vfst appearing on said pixel electrode right after said on-state period; symbol Vopt denotes an optimum electric potential [V] with said electric potential Vfst of said pixel electrode held as it is; and symbol Vsig denotes an electric potential Vsig [V] appearing on said positive-polarity data line in said hold period.