GB757811A - Method and apparatus for fabricating grid structures for cathode ray tubes - Google Patents

Abstract

757,811. Colour television electrodes. CHROMATIC TELEVISION LABORATORIES, Inc. Dec. 22, 1953 [Jan. 14, 1953], No. 35586/53. Class 39 (1). [Also in Group XXII] Grid electrodes are made by temporarily securing a plurality of closely spaced wires in parallel relationship or winding a continuous wire to form a plurality of closely spaced turns before securing, positioning the so-formed set of anchored wires at the desired separation distance, tautening the wires and positioning a final anchoring frame adjacent to the taut wires and securing them thereto, e.g. by means of cement. The grids are wound on a drum 23 with two opposed slots 27 wide enough each to receive two holders 31 faced at 33 with rubber or rubberized fabric and wedging cams or shims. The wire is fed through a laterally moving guide 17 as the drum rotates and, after the winding operation, is secured to the holders by clamp bars 35 and bolts 43. The wires 11 are severed along line 51, the shims removed, and the grids in the holders 31 transferred to a bed-plate 63 (Fig. 1). One holder 31 is clamped in blocks 65, 67 and the wires are laid across guide slots in the bar 69, 69<SP>1</SP> and over the frame 75 to which the grid is to be secured, the other holder 31 being either allowed to overhang the bed-plate or spring-loaded. There may be insulating material between the wires 11 and the frame 75. With the grid wires taut and aligned across the frame 77, cement which may be of insulating material is applied at 83 having an expansion co-efficient close to those of the grid wire and the frame. After removing the holders 31, the grid assembly is baked to harden the cement, the grid wires being of material with an expansion co-efficient greater than the support frame to prevent fracture at this stage. Stainless steels of different expansion co-efficients are instanced. Alternatively the upturned edges of frame 77 may be of glass and a glass core is laid across the wires at that point, and the whole is fused by heating. Welding, hard soldering, brazing and other techniques may be used to secure the wires to the frames. Instead of winding a single wire, a plurality of wires may be drawn from spools through aligned openings and clamped at points corresponding to the desired length of the grid, a third clamp being applied to the wires which are then cut between the second and third clamp, permitting the production of a succession of grids. The distances apart of the positioning slots may be progressively different if a grid of this form is required, as in cathoderay tubes. Specifications 721,523, 757,787 and 757,879 are referred to.