METODO E DISPOSITIVO PER REGOLARE LA CONVERGENZA IN CINESCOPI A COLORI

The aim of setting the convergence is to ensure that the intensity centres (SB, SG, SR) of the three electron beams (EB, EG, ER) coincide in the region of the hole mask. In the case of in-line picture tubes, precise setting, particularly in the horizontal direction, runs into difficulties because of the wide shadowing of the electron beams (EB, EG, ER) by the slotted mask. This problem is solved according to the invention, in that the brightness of the fluorescent strips (B, G, R), which are excited by the respective electron beam (EB, EG, ER), of the screen is measured incrementally by means of a high-resolution diode arrangement. In each case one mean value, which is weighted over the measurement path, is formed from the incremental brightness values derived in this way. These values give a good approximation of the relative position of the intensity centres (SB, SG, SR) with respect to one another. The difference (KFB and KFR) from the mean value of the central electron beam (EG) is the measure of the divergence of the two electron beams (EB, ER).