GB657490A - Improved deflection coils for cathode ray tubes - Google Patents

Abstract

657,490. Electric coils. BRITISH THOMSON-HOUSTON CO., Ltd. Oct. 10, 1947, No. 27280. Convention date, Oct. 12, 1946. [Class 35] [Also in Group XL (a)] An electromagnetic device for deflecting the beam in a cathode-ray tube in two directions over the fluorescent screen comprises a core, Fig. 2, of steel wire or ribbon wound into a coil 5 and surrounded by a non-magnetic, preferably copper sleeve 6, and a plurality of coils 15, wound longitudinally on the composite core to the same depth, alternate and intermediate coils being respectively connected to form the two deflecting circuits. Insulators 9, 10, 11, 12 of cellulose acetate space the coils from the core and C-shaped guides 14, also of cellulose acetate separate adjacent coils from one another; the guides 14 fit in notches at the ends of members 9, 10. The wire of the core has its longer crosssectional dimension perpendicular to the longitudinal axis of the coil into which it is' wound, and is of high permeability material. The non- magnetic sleeve 6 serves to increase the reluctance of the flux path external to the wound coil of the core, and may have flared ends as shown to hold the coil in position. In winding the coils, those of the vertical deflecting winding are wound first ; an insulator 40 is then wrapped round the assembly and the horizontal deflecting coils are wound on. The Specification as open to inspection under Sect. 91 refers to differing numbers of turns in the different coils. This subject-matter does not appear in the Specification as accepted.