Circuit arrangement for use in a television camera tube with an anti-comet tail electron gun

A circuit arrangement suitable for use with a television camera tube provided with a target plate an anti-comet tail electron gun, said gun having a cathode, a control electrode, anode electrodes and a lens electrode means for generating during line scan times and line flyback times an electron beam having different values of beam diameter, beam current intensity and potential upon impact on said target plate, a line period comprising the line scan time and a line blanking time comprising the line flyback time and a beam blanking time, said circuit arrangement comprising an input means for coupling to at least one of said anode electrodes present in the camera tube, a measuring circuit means for sampling a signal during the line flyback time coupled to said input means, said measuring circuit including a comparison circuit means for storing a sampled signal and for comparing two successively sampled and stored signals, and a control circuit coupled to the comparison circuit in the measuring circuit and having an output means for coupling to the lens electrode in the camera tube and for providing a changed lens adjustment during the line flyback times in case of unequal sampled signals in the comparison circuit for the purpose of eliminating the inequality.