Electromagnetic and electrostatic shielding for electronic equipment

Abstract

A method and structure for assembling cathode ray tube electronic equipment is disclosed in which a sheet metal cage is assembled inside the plastic housing to enclose the electronic components. The face of the cathode ray tube is covered with a fine conductive mesh which is engaged by the bezel surrounding the front edges of the cathode ray tube. A projecting lip on the inner edge of the bezel, contoured to match the tube face, engages the mesh to keep it flat and smooth against the face of the tube. Simultaneously, flanges on the front of the cage are attached by self-tapping screws to bosses on the back side of the bezel so as to capture the edges of the mesh in conductive contact against the cage flanges. Conductive gaskets may be used to improve the electrical contact between the parts and thus improve the tightness of the shield. Internal shielding may also be provided by can-shaped shields affixed to the vertical walls of the cage and positioned so as to enclose components mounted on horizontal surfaces inside the cage. The decorative housing mates with the rear edge of the bezel and is attached to the rear of the cage by self-tapping screws. These piece parts may be selectively assembled into equipment cabinets with varied levels of shielding by using or omitting various shielding elements such as the mesh, the gaskets, the number of assembly screws or the various surfaces of the shielding cage.