GB837102A - Improvements relating to electron guns - Google Patents

Abstract

837,102. Electron guns. SYLVANIA ELECTRIC PRODUCTS Inc. Nov. 19, 1956 [Nov. 25, 1955], No. 35356/56. Class 39(1). In a cathode ray monochrome or colour receiving tube the gun comprises a ceramic block having a recess housing the elongated indirectly heated cathode 34, Fig. 3, and an anode electrode plate 50 having an elongated slot 52 secured over the top of the block, the block supporting thereon, Fig. 5, or in grooves therein, Fig. 3, one or more beam splitter electrodes 42 and one or more intensity control electrodes 44, 46, the electrodes 42, 44, 46 extending across the slot 52 and the splitter electrode(s) dividing the single beam emitted by the cathode into two or more equal or unequal parts, at least one part being controlled by an intensity control electrode 44 and the beam splitter electrode(s) being in electrical contact with anode electrode plate 50. The beam parts may pass through a subsequent common electrostatic focusing lens and a magnetic scanning yoke. The ceramic block may have grooves housing 42, 44, 46 and end supports 36 for the cathode the latter supports being bonded to the block. The control electrodes 44, 46 are insulated from 42, 50. It is stated that one or both of the intensity control electrodes can be eliminated or each beam can have a separate intensity control electrode. In a modification (not illustrated) the ceramic block can be cylindrical with a central recess housing a disc cathode. By varying the thickness of the beam splitters, the spacing between the beams can be varied. In a practical method of assembly, Fig. 5, wire is wrapped in a bifilar helix, the wires of which are of different diameter around the ceramic block which has grooves for the cathode supports, as in Fig. 3. The top of the block and conductors 42, 44, 46 are painted with fret which is then removed from the top of the beam splitters 42, the electrode 50 gold plated on the underside is placed in contact with the beam splitters and the structure is fired in an oxidising atmosphere to solder the beam splitters and electrode 50 together and to bind the wires 44, 46 to the ceramic block by melting the frit. Wires 42, 44, 46 are now severed at the lower part of the block and trimmed at the upper edge, 44, 46 being trimmed at one edge only to give leads at the other ends. The particular forms shown has two intensity control electrodes and three beam splitters, the diameter of the intensity control electrode wire being less than that of the beams splitter wire. If the slot in electrode 50 is not rectangular a plurality of non coplanar beams can be produced. The gun can be used in oscilloscopes giving a plurality of test patterns simultaneously, in colour television having two or four beams. Specification 817,762 is referred to.