Image sticking measurement method for liquid crystal display device
First Claim
1. A method for measuring an image-sticking defect in a liquid crystal display device, comprising:
- irradiating light from a backlight to the liquid crystal display device;
displaying a first full white state on a liquid crystal display screen of the liquid crystal display device to which the light is irradiated;
measuring first luminance values of a plurality of designated points on the liquid crystal display screen;
calculating an average luminance value of the first full white state using the first luminance values;
displaying a full black state on the liquid crystal display screen;
measuring second luminance values of the plurality of designated points on the liquid crystal display screen;
calculating an average luminance value of the fall black state using the second luminance values;
forming a gray scale using the average luminance value of the first full white state and the average luminance value of the full black state;
displaying a second full white state on the liquid crystal display screen; and
measuring a luminance change of the second full white state with time at the plurality of designated points using the gray scale.
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Abstract
A method for measuring an image-sticking defect in a liquid crystal display device includes steps of irradiating light from a backlight to the liquid crystal display device, displaying a first full white state on a liquid crystal display screen of the liquid crystal display device to which the light is irradiated, measuring first luminance values of a plurality of designated points on the liquid crystal display screen, calculating an average luminance value of the first full white state using the first luminance values, displaying a full black state on the liquid crystal display screen, measuring second luminance values of the plurality of designated points on the liquid crystal display screen, calculating an average luminance value of the full black state using the second luminance values, forming a gray scale using the average luminance value of the first full white states and the average luminance value of the full black state, displaying a second full white state on the liquid crystal display screen, and measuring a luminance change of the second full white state with time at the plurality of designated points using the gray scale.
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Citations
18 Claims
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1. A method for measuring an image-sticking defect in a liquid crystal display device, comprising:
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irradiating light from a backlight to the liquid crystal display device;
displaying a first full white state on a liquid crystal display screen of the liquid crystal display device to which the light is irradiated;
measuring first luminance values of a plurality of designated points on the liquid crystal display screen;
calculating an average luminance value of the first full white state using the first luminance values;
displaying a full black state on the liquid crystal display screen;
measuring second luminance values of the plurality of designated points on the liquid crystal display screen;
calculating an average luminance value of the fall black state using the second luminance values;
forming a gray scale using the average luminance value of the first full white state and the average luminance value of the full black state;
displaying a second full white state on the liquid crystal display screen; and
measuring a luminance change of the second full white state with time at the plurality of designated points using the gray scale. - View Dependent Claims (2, 3, 4, 5, 6, 7)
measuring a luminance value of the backlight while displaying the first full white state on the liquid crystal display;
measuring a luminance value of the backlight while displaying the full black state on the liquid crystal display; and
obtaining an inherent luminance value of the backlight.
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4. The method according to claim 3, wherein the step of obtaining an inherent luminance value of the backlight includes comparing the luminance value of the backlight of the first full white state to the luminance value of the backlight of the full black state.
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5. The method according to claim 4, further comprising:
calculating a transmission percentage ratio of the average luminance value of the first full white state to the inherent luminance value of the backlight.
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6. The method of claim 5, further comprising:
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obtaining a luminance change percentage ratio by calculating a ratio of a brightest luminance value to a darkest luminance value of the second full white state at the plurality of designated points; and
measuring the image-sticking defect using a difference between the transmission and the luminance change percentrage ratio.
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7. The method according to claim 1, wherein a voltage applied to the liquid crystal display device during the step of displaying a first full white state is equal to a voltage applied to the liquid crystal display device during the step of displaying a second full white state.
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8. A method for quantifying an image-sticking defect of a liquid crystal display device, comprising:
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displaying a first full white state on a liquid crystal display screen of the liquid crystal display device via a backlight source;
calculating an average luminance value of the first full white state using luminance measurement values of a plurality of designated points on the liquid crystal display screen;
measuring a first luminance value of the backlight source;
displaying a full black state on the liquid crystal display screen;
calculating an average luminance value of the full black state using luminance measurement values of the plurality of designated points on the liquid crystal display screen;
measuring a second luminance of the backlight source;
generating a gray scale with the average luminance values of the first full white and full black states, the gray scale having 64 levels;
displaying a second full white state on the liquid crystal display screen;
measuring a brightest luminance value and a darkest luminance value;
calculating a luminance change ratio using the brightest luminance value and the darkest luminance value;
calculating a transmission ratio using the average luminance value of the first full white state and the first luminance value of the backlight source; and
quantifying the image-sticking defect using the luminance change ratio and the transmission ratio. - View Dependent Claims (9, 10, 11, 12, 13, 14)
where δ
white is the luminance change ratio, Maxwhite is the brightest luminance value, and Minwhite is the darkest luminance value.
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14. The method according to claim 8, wherein the transmission ratio is calculated using the follow equation:
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15. A method for generating a gray scale of a liquid crystal display device, comprising:
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displaying a full white state on a liquid crystal display screen of the liquid crystal display device;
calculating an average luminance value of the full white state using luminance measurement values of a plurality of designated points on the liquid crystal display screen;
displaying a full black state on the liquid crystal display screen;
calculating an average luminance value of the full black state using luminance measurement values of the plurality of designated points on the liquid crystal display screen; and
generating a gray scale with the average luminance values of the full white and black states. - View Dependent Claims (16, 17)
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18. A method for measuring a luminance change ratio of a liquid crystal display device, comprising:
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displaying a first full white state on a liquid crystal display screen of the liquid crystal display device;
calculating an average luminance value of the full white state;
displaying a full black state on the liquid crystal display screen;
calculating an average luminance value of the full black state;
generating a gray scale with the average luminance values of the full white and black states;
displaying a second full white state on the liquid crystal display screen;
measuring brightest and darkest luminance values; and
calculating the luminance change ratio using the brightest and darkest luminance values.
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Specification