| 摘要 |
697,188. Ion-trapping in cathode-ray tubes. PHILIPS ELECTRICAL INDUSTRIES, Ltd. April 9, 1951 [April 12, 1950], No. 8179/51. Class 39(i) In cathode ray receiv ing apparatus in whicl a magnetic field co operates with an ion trap electrode to remov ions from the beam the electrode is cylin drical and has an aper tured stop, and the stop is pervious to negativ ions to a progressively decreasing extent fron the edge of the aperture so that the residual ion spot on the screen ha blurred edges and is thus less noticeable. The aperture may be milled on one or as shown in Fig. 4 on two opposing portions; the milled portions may be of rectangular section instead of conical and may or may not be radial, Figs. 6, 7 (not shown), or small holes may be distributed as shown in Fig. 8. The ion trap may use crossed electric and magnetic fields so the electrons are undeviated and the ions intercepted, the transverse electric field being produced by inclining the end surface of the cylinder to the axis thereof at the point of entry, Fig. 1 (not shown), or may use a magnetic deflecting field only, in which case the electrode must be bent as shown in Fig. 2. The aperture in the stop need not be circular or concentrically positioned and the cylindrical electrode need not be of circular cross-section. The cylindrical electrode may be a conductive coating or a metal part of the tube wall. |
