GB864945A - Arrangement for the magnetic deflection of electron beam in cathode ray tubes, particularly for television purposes - Google Patents

Abstract

864,945. Electron beam deflecting apparatus. GRAETZ, E. Jan. 29, 1958 [Feb. 23, 1957], No. 2980/58. Class 39(1). A deflecting coil system for a cathode-ray tube has toroidal coils, wound on a ferromagnetic yoke, for effecting deflection in at least one direction, preferably the vertical direction, the layers of each toroidal coil being wound in a continuous process and each layer extending over an azimuthal angle smaller than that covered by the entire coil and the arithmetic mean of the angles occupied by the odd layers being different from the arithmetic mean of the angles occupied by the even layers. In Fig. 5 the coil is wound from A to E, the odd layers 1, 3.. 13 occupying 30 degrees each, and the even layers 2, 4.. 12, 15 degrees, according to the scheme indicated in Fig. 6. In a modification the winding scheme is as shown in Fig. 7 with the ratio of the angles occupied by two consecutive layers varying between the centre of the coil and the ends. The variation may be so chosen that the thickness of the coil varies according to a cosine function. The even layers may be wound with a pitch different from that used in the odd layers. The coils for producing deflection in the horizontal direction may be similar toroidal coils, or saddle coils whose turns may or may not be distributed according to a cosine function.