Videocolor

Michel Faivre

Guy Legrand

Jean-Pierre Fourche

Olivier Berthaut

For the automatic determining of the characteristics of the corrections to be made in trichromatic cathode tube deflectors, measurements are made of the coordinates of the midpoints of the bars R and B of a crossed bar test pattern at 'strategic' places. With the deflector in the 'mean' position on the tube, the values obtained are standardized by computation to re-establish virtually the ideal position of the deflector, the convergence errors due to this deflector are computed and the pinpoint or overall corrections to be made to it are deduced therefrom.

Method for the automatic measurement of convergence and for the

Monochrome bar patterns approximately seven millimeters in width are produced on the screen of a three-color television picture tube by means of a video signal having a substantially Gaussian waveform. The value of the convergence component is given by the distance between centers of two bars of different colors. Measurement of convergence is carried out by means of a photosensor consisting of a charge-coupled photosensitive strip and an optical system comprising a biconvex lens and a cylindrical lens.

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Dijon, France

Michel Faivre