Patent ID: 7215378

Claim:
A display comprising a cathode ray tube for displaying an image thereon; and a calculation circuit connected to said cathode ray tube for centering and dimensioning the image being displayed by (a) measuring durations of vertical border edges of the image and iteratively modifying adjustment values for a horizontal centering of the image to obtain equal lateral vertical edges, (b) measuring the durations of the vertical border edges of the image to calculate adjustment values for a horizontal dimension of the image to cause the vertical border edges to disappear, and (c) measuring durations of horizontal border edges of the image to calculate adjustment values of a vertical dimension of the image, and to calculate adjustment values of a vertical centering of the image to cause the horizontal border edges to disappear and to center the image vertically; said calculation circuit further checking stability of the image at a start of at least one of the steps (a), (b) and (c), by (a 0 ) measuring a pair of durations of at least one of the vertical and horizontal border edges of the image, (a 1 ) subtracting two successive measurements to determine a variation in the durations, (a 2 ) cornparing the variation with a first threshold, and stopping if the first threshold is exceeded or continuing if the first threshold is not exceeded, and (a 3 ) comparing the measurements with a second threshold, and stopping if the second threshold is exceeded or continuing with at least one of steps (a), (b) and (c) if the second threshold is not exceeded.