Method of driving a display unit

Claim 1

A method of driving a display unit having matrix-arranged pixel electrodes (A) each connected via a capacitor (8) to a first line, each pixel electrode being connected to a switching element (3) which is electrically connected to an image signal line (2) and to a scan signal line (1), and display material held between said pixel electrode (A) and an opposing electrode and being AC driven, wherein an image signal voltage (Vsig) is transmitted to said pixel electrode (A) during an on-period of said switching element (3), and a modulating signal (Ve) is applied to said first line during an off-period of said switching element, thereby changing the potential of said pixel electrode, characterized in that said modulating signal (Ve) is generated, so that said changed potential is superposed upon, or cancelled out from, said image signal voltage (Vsig), the polarity of said image signal voltage (Vsig) transmitted during the on-period of said switching element (3) being reversed alternately for each vertical scanning period, and the polarity of said modulating signal (Ve) applied to said first line during the off-period of said switching element (3) being reversed alternately for each vertical scanning period, the resultant voltage being applied across said display material.

Claim 4

A method of driving a display unit according to any one of claims 1 to 3, wherein said switching element (3) is a thin film transistor (TFT) and a relationship between Ve(+) and Ve(-) of said modulating signal (Ve) with its polarity reversing alternately for each scan line and a scan signal voltage (Vg) is given by: CsVe(+) + CgdVg = CsVe(-) - CgdVg where Cs is a storage capacitor (8), Cgd is a gate-drain capacitor (4) and Csd is a source-drain capacitor (5) of said thin film transistor (3).

Claim 5

A method of driving a display unit according to any one of claims 1 to 4, wherein the potential of said opposing electrode of the display unit is constant at least during each field period.

Claim 6

A method of driving a display unit according to any one of claims 1 to 4, wherein the potential of said opposing electrode of the display unit is constant and equal to the average center potential of said image signal voltages (Vsig).

Claim 7

A method of driving a display unit according to any one of claims 1 to 4, wherein the potential of said opposing electrode is electrically made floated.

Claim 8

A method of driving a display unit according to any one of claims 1 to 7, wherein said first line is used in common with said scan signal line (1), and said modulating signal (Ve) is applied to said scan signal line superposing upon said scan signal (Vg).

Claim 9

A method of driving a display unit according to any one of claims 1 to 8, wherein the average DC voltage among said opposing electrode, image signal line (2) and pixel electrode (A) is smaller than CgdVg/Σ C, where Σ C is the total electrostatic capacitance per one pixel.

Claim 10

A method of driving a display unit according to any one of claims 1 to 9, wherein Ve(+) and Ve(-) of said modulating signal voltage (Ve) are set so as to satisfy the following formula: Vth ≦ Δ V* ≦ Vmax where ΔV* is expressed by: ΔV* = (Ve(+) + Ve(-)) Cs/2Ct Ct = Cs + Cgd + Csd + Clc where the voltage range within which the transmission factor of a liquid crystal changes is from Vth to Vmax, Cs is the storage capacitor, Cgd is a gate-drain capacitor, Csd is a source-drain capacitor, and Clc is the liquid crystal capacitor.