Image sticking measurement method for liquid crystal display device
AssigneeLG.Philips LCD Co., Ltd.
InventorMan-Hoan Lee
Life of this patent
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Abstract
A method for measuring an image sticking defect in a liquid crystal display device includes the steps of grounding a liquid crystal cell, the liquid crystal cell includes an alignment layer, applying a first alternating current voltage to the liquid crystal cell, measuring a first capacitance of the liquid crystal cell, applying an electrical stress to the liquid crystal cell, measuring a second capacitance of the liquid crystal cell, and calculating a capacitance difference between the first capacitance and the second capacitance.
Claims23
A method for measuring an image sticking defect in a liquid crystal display device, comprising:
- grounding a liquid crystal cell, the liquid crystal cell including an alignment layer;
- applying a first alternating current voltage to the liquid crystal cell;
- measuring a first capacitance of the liquid crystal cell;
- applying an electrical stress to the liquid crystal cell;
- measuring a second capacitance of the liquid crystal cell;
- and
- calculating a capacitance difference between the first capacitance and the second capacitance.
A method for measuring an image sticking defect in a liquid crystal display device, comprising:
- applying a first alternating current voltage to a liquid crystal cell;
- measuring a first capacitance of the liquid crystal cell;
- electrically connecting a thin film transistor to the liquid crystal cell;
- applying a second alternating current voltage to the thin film transistor, the second alternating current voltage is selected from a group comprising alternating current voltages each having different waveforms and alternating current voltages each having different voltage values;
- combining the second alternating current voltage with an off-set voltage occurring in the thin film transistor to obtain a combined voltage;
- applying the combined voltage to the liquid crystal cell;
- measuring a second capacitance of the liquid crystal cell;
- calculating a capacitance difference between the first capacitance and the second capacitance;
- and
- calculating a quantified value of the image sticking defect by the following equation:
- y=Avr(ΔC/C1)−α(ΔC/C1)
- wherein “y” is the quantified value of the image sticking defect, C1 is the first capacitance, ΔC is the capacitance difference between the fist capacitance and the second capacitance, “Avr(ΔC/C1)” is an average of capacitance differences when the second alternating current voltage is applied as the thin film transistor, and “α” is a value of the second alternating current voltage applied to the liquid crystal cell.
A method for measuring an image sticking defect in a liquid crystal display device, comprising:
- applying a first alternating current voltage to a liquid crystal cell;
- measuring a first capacitance of the liquid crystal cell;
- electrically connecting a thin film transistor to the liquid crystal cell;
- applying a second alternating current voltage to the thin film transistor, the second alternating current voltage is selected from a group comprising alternating current voltages each having different waveforms and alternating current voltages each having different voltage values;
- combining the second alternating current voltage with a direct current voltage having a same value as a residual direct current occurring in the liquid crystal cell to obtain a combined voltage;
- applying the combined voltage to the liquid crystal cell;
- measuring a second capacitance of the liquid crystal cell;
- calculating a capacitance difference between the first capacitance and the second capacitance;
- and
- calculating a quantified value of the image sticking defect by the following equation:
- y=Avr(ΔC/C1)−α(ΔC/C1)
- wherein “y” is the quantified value of the image sticking defect, C1 is the first capacitance, ΔC is the capacitance difference between the first capacitance and the second capacitance, “Avr(ΔC/C1)” is an average of capacitance differences when the second alternating current voltage is applied to the thin film transistor, and “α” is a value of the second alternating current voltage applied to the liquid crystal cell.
Dependencies are inferred from the claim text.