Abstract: An electromagnetic deflection unit (5) comprising a coil holder (6) with a flange (8) whose inner side supports coils (10a, 10b) for (line) deflection of electron beams. At the flange side of the coil holder (magnetized) preformed elements (14) are arranged within these coils so as to influence the magnetic field of these coils (10a, 10b), thereby reducing spreading errors, caused during manufacture, throughout the display screen. For the purpose of automatic mounting of the preformed elements, an annular support having predetermined locations (in particular from 12 to 36) for accommodating preformed elements is used. The preformed elements (14) are accommodated at a plurality of these predetermined locations and, if made of a permanent magnetic material, produce magnetic fields having magnetic strengths measured at a distance of some mm above the heart of the elements in the range between 1 and 1000 .mu.T.

Abstract: Display device includes a cathode ray tube having an envelope 1 with a number of reference surfaces on the walls of V-shaped grooves provided on positioning studs 14. The deflection unit 10 is provided with adjustable camming members 15 which lie against respective reference surfaces. The position of the deflection unit 10 relative to the envelope 1 can be adjusted by rotating camming members 15.