Color convergence apparatus for a color television tube

Claim 1

Apparatus for providing convergence of the three beams from three electron guns, respectively, in a tri-color TV tube of the shadow mask type, the guns being disposed along a circle radially from an axis extending between the center of the screen and the base of the tube, deflection of the three beams on the screen of the tube being responsive to both periodic currents and nonperiodic currents provided to the horizontal and vertical coils of a deflection yoke around the neck of the tube, said tube also having a convergence yoke comprised of at least three convergence coils respectively corresponding to said guns, for providing additioNal deflection to each of said respective guns in response to convergence currents provided to each convergence coil comprising: first and second sensing means connected to the horizontal and vertical deflection coils respectively for providing horizontal and vertical signals proportional to the horizontal and vertical deflection currents, including providing said horizontal and vertical signals when said deflection currents are periodic and when said deflection currents are nonperiodic; first and second multiplying means connected to said first and second sensing means respectively, said first multiplying means being responsive to said horizontal signal and providing a first output signal proportional to the square of said horizontal signal, including providing said first signal when said horizontal signal is representative of a periodic signal and when said horizontal signal is representative of a nonperiodic signal, said second multiplying means being responsive to said vertical signal and providing a second output signal proportional to the square of said vertical signal, including providing said second signal when said vertical signal is representative of a periodic signal and when said vertical signal is representative of a non-periodic signal; signal attenuating means connected to said horizontal, vertical, first and second signals for providing a plurality of selectively attenuated signals, including at least one attenuated signal for each of said horizontal, vertical, first and second signals; and first, second and third combining means, each responsive to selected ones of said attenuated signals and each providing a convergence current representative of a combination of said attenuated signals to one of the convergence coils for providing convergence to the beams of the three electron guns when said beams are deflected in response to periodic currents and when said beams are deflected in response to non-periodic currents.