Radiation shield with opaque and transparent portion

Abstract

An auxiliary radiation shield for a CRT-type video display terminal includes a generally flat front portion having an at least partially transparent conductive central shield and an opaque frame-like conductive outer shield surrounding the central shield, with the transparent central shield having an area substantially equal to that of the faceplate of the CRT and the opaque outer shield having an area at least equal to that of the transparent central shield, whereby when the radiation shield is supported in front of the CRT with the transparent central shield disposed directly in front of the faceplate, the transparent central shield is in the path of the electrical field that would otherwise extend through the faceplate towards any user in front of the CRT, and the opaque outer shield intersects a substantial portion of the electrical fields that would otherwise extend from the sides and top of the CRT towards that user. Preferably, both the central shield and the outer frame are not only electrically conductive but are also connected to ground, thereby providing an alternate return path for electrical charges that would otherwise pass from the monitor to the user. In at least one presently contemplated embodiment, at least the opaque shield portion is not only electrically conductive (high permittivity), but also magnetically conductive (high permeability) whereby a significant portion of the electromagnetic radiation that is not reflected is propagated within the shield until it is eventually absorbed and dissipated. The absorption can be further enhanced by including an extension of the outer shield that is oriented parallel to the direction of propagation.

Dependencies are inferred from the claim text.