| 摘要 |
708,137. Cathode-ray tubes. PHILIPS ELECTRICAL INDUSTRIES, Ltd. Aug. 27, 1951 [April 23, 1951], No. 20142/51. Class 39(1) [Also in Group XXXV] A cathode-ray t u b e having one or more deflecting coils is provided with one or more non- conductive permanent magnets adjacent the coils to adjust the position of the beam, the ratio between the remanent induction and the coercive field strength of the magnet material being four at the most so that deflection errors are not caused by eddy currents in the permanent magnet. The tube may be used in radar for P.P.I. or in television. Segmental poles of the material, which as described in Specification 708,127, [Group XXXV], comprises non-cubic crystals of polyoxides of iron and at least one of the metals barium, strontium, lead and calcium, are secured to a ring 5, Fig. 1, of ferrite or sheet iron adjacent the motor-driven rotatable deflecting coils 3. In a modification, two sets of poles 7, 8, Fig. 3, are arranged in two rotatable rings 6, 6<SP>1</SP>. |
