Schaltungsanordnung zur magnetischen Ablenkung eines Kathodenstrahls

摘要

672,075. Television. RADIO CORPORATION OF AMERICA. April 28, 1950 [April 30, 1949], No. 10526/50. Class 40 (iii). [Also in Group XL (c)] Fig. 1 shows an electromagnetic scanning circuit for a cathode-ray tube 56 in which a saw-tooth voltage from a source 10 is applied via a cathode follower stage 20 to the grid of a driver stage 38 to produce a saw-tooth current flow in the deflecting coils 54, a portion of the scanning current being supplied by the damping diode 72. Capacitors 62 and 74 are charged during the period of current flow through diode 72 in such a direction that the H.T. supply from point 70 to the anode circuit of the driver stage 38 during its conductive periods is supplemented by the voltage across the capacitors. The linearity of the scan may be adjusted by variation of inductor 76 which resonates with capacitor 74 and may be adjusted to compensate for the deviation from flatness of the screen of the cathode-ray tube 56. The fly-back voltage developed across a pulse transformer 66 in the anode dircuit of valve 38 is rectified by diode 82 and smoothed to provide E.H.T. voltage for the final anode 78 of the cathode-ray tube. The stray capacitance 39 associated with the anode of valve 38 may be supplemented to lower the resonant frequency of the circuit comprising stray capacitances 39, 55, 57 and transformer winding 64 and thus improve the linearity of scan. Fig. 2 shows a modification in which the synchronizing signals from a television receiver 100 are separated in unit 104, and applied to line and frame saw-tooth generators 106, 108, respectively, H.T. supply being derived from a unit 110. The H.T. supply to the driver stage 38 from unit 110 is increased by the voltages produced across capacitors 621 and 741 as described in connection with Fig. 1. The capacitors 621, 741 and wave shaping inductor 761 are associated with the end of the deflecting coils 54 which is at a low A.C. potential, thus obviating the necessity of filtering out the high voltage fly-back potential which is periodically present at end 58 of the coils.