GB555015A - Magnetic coils and arrangements utilising the same - Google Patents

Abstract

555,015. Electric coils. STANDARD TELEPHONES & CABLES, Ltd. March 28, 1942, No. 4164. Convention date, Jan. 10, 1941. [Class 35 ] [Also in Group XL] A magnetic coil for producing a uniform field within a specified space, such as the cylindrical space occupied by an image dissector, comprises a number of serially connected coaxial windings each of one or more turns wound over an ellipsoidal surface, the common axis of the windings being perpendicular to an axis of the surface. The coil is supplied with electric current in such - manner that the ampere-turns per unit length measured along the common axis is constant, if the coils are simply connected in series, this means that the turn density per unit length of the cornmon axis is constant, but the turn density may be varied and certain coils may be shunted to vary the current through them. The cylindrical image dissector 10 is surrounded by sweep coils 11, 12 wound on prolate spheroids one within the other. The focusing coil 13 is also wound on a prolate spheroid. The coils must be bent away from the axis at 30, 31 to allow the image to be projected on the photo-electric screen 14. The focusing ring coatings 16 are connected to points of successively higher potential on a voltage divider. The axis of the sweep coils must be displaced by an angle from the position they would occupy in the absence of the focusing coil, the presence of which alters the direction of deflection of the electron stream. For film scanning only one deflection coil is needed. The shells on which the coils are wound are split into halves to facilitate assembly. The Specification as open to inspection under Sect. 91 included coils wound on cylindrical surfaces. On account of the non-uniformity introduced by the finite length of the coils, the cathode is disposed in the centre. This subjectmatter does not appear in the Specification as accepted.