METHOD OF SOFTWARE-BASED COMPENSATION OF TECHNOLOGICAL VARIATION IN CHROMATICITY COORDINATES OF LCD PANELS

Subject of research. The problem of software-based compensation of technological variation in chromaticity coordinates of liquid crystal panels is considered. A method of software-based compensation of technological variation in chromaticity coordinates is proposed. The method provides the color reproduction characteristics of the series-produced samples on-board indication equipment corresponding to the sample equipment, which is taken as the standard. Method. Mathematical calculation of the profile is performed for the given model of the liquid crystal panel. The coefficients that correspond to the typical values of the chromaticity coordinates for the vertices of the triangle color coverage constitute a reference mathematical model of the plate LCD panel from a specific manufacturer. At the stage of incoming inspection the sample of the liquid crystal panel, that is to be implemented within indication equipment, is mounted on the lighting test unit, where Nokia-Test control is provided by the formation of the RGB codes for display the image of a homogeneous field in the red, green, blue and white. The measurement of the (x,y)-chromaticity coordinates in red, green, blue and white colors is performed using a colorimeter with the known value of absolute error. Instead of using lighting equipment, such measurements may be carried out immediately on the sample indication equipment during customizing procedure. The measured values are used to calculate individual LCD-panel profile coefficients through the use of Grassman's transformation, establishing mutual relations between the XYZ-color coordinates and RGB codes to be used for displaying the image on the liquid crystal panel. The obtained coefficients are to be set into the memory of the graphics controller together with the functional software and then used for image displaying. Main results. The efficiency of the proposed method of software-based compensation for technological variation of chromaticity coordinates of liquid crystal panel was estimated by the ratio criterion of the areas of cross sections of the histograms p(x,y) at a given probability confidence level, calculated before and after compensation procedure. The sections of histograms, representing distributions of chromaticity coordinates were obtained by mathematical simulation in MathCad 15.0. The simulation software of the method of software-based compensation gives the possibility to obtain the mutual arrangement between the figures formed by sections of the histograms of (x,y)-chromaticity coordinates, and it may be observed as significant reduction of the area after compensation procedure is performed, and changes in the geometry of the cross section shape as well. Sets of dependency curves were obtained, depicting the efficiency criterion value versus resolution of the colorimeter that is used for measuring the chromaticity coordinates. Practical relevance. Research results are usable for engineers who are designing modern indication equipment based on LCD-panels and by manufacturers for colorimetric calculations and for estimation of technological tolerance of chromaticity coordinates among display units in mass production as well.

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