Electron gun with electrostatic shielding and method of assembly therefor

For use in an Einzel lens having a plurality of spaced, charged grids for directing an electron beam along an axis and for focusing said electron beam on a faceplate of a cathode ray tube (CRT), an arrangement for facilitating alignment of said charged grids during assembly of said Einzel lens, said arrangement comprising:

• first and second cylindrical hollow grids disposed in a spaced manner along and having respective longitudinal axes coincident with said axis along which the electron beam is directed, wherein each of said first and second grids has a same inner diameter d and is charged to an anode voltage V.sub.A ;
• a third cylindrical hollow grid disposed in a spaced manner intermediate said first and second grids and charged to a focus voltage V.sub.F, where V.sub.F <F.sub.A, and wherein said third grid also has said inner diameter d;
• and
• cylindrical mandrel means having an outer diameter D, where D<d, and wherein said mandrel means is adapted for tight-fitting positioning within said first, second and third grids for supporting said grids in mutual alignment along said axis during assembly of said Einzel lens.

A method for assembling an electron gun having an Einzel lens, said method comprising the steps of:

• providing a plurality of hollow, cylindrically shaped grids including first, second and third grids each having an inner diameter d;
• aligning said plurality of grids along a common axis, including inserting a cylidrical mandrel having an outer diameter D within said first, second and third grids for supporting and maintaining said first, second and third grids in common alignment on said axis, where D<d;
• and
• attaching said plurality of grids to a plurality of rigid, insulating support members in assembling said electron gun.