Device for Detecting a Fixed Image on a Liquid Crystal Display Screen
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Abstract
A device for detecting a frozen image on a liquid crystal display screen comprises at least one photoelectric cell capable of delivering a luminance signal l(t) to means (8) for processing this signal. The cell is placed facing a display area (A) of the screen. In this display area, a variable pattern is displayed at a characteristic frequency fc. The processing means are capable of detecting the characteristic frequency in the signal l(t). If this signal is not detected, they trigger a corresponding alarm.
17 Citations
27 Claims
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1-12. -12. (canceled)
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13. A device for detecting a frozen image on an active-matrix liquid crystal display screen, comprising:
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a photoelectric cell covering a display area of said screen, said cell being capable of delivering an electrical signal representative of luminance in said area;
control means for displaying a variable pattern at a characteristic frequency in said display area;
means for processing an electrical signal delivered by said cell, in order to detect said frequency; and
means for displaying an alarm should said frequency not be detected. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 25, 26, 27)
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Specification