Shielded cathode ray tube

A shielded CRT, comprising:

• a CRT having a neck portion and a non-shielded display face;
• secondary shielding means for enclosing said CRT and for inhibiting electromagnetic emissions therefrom, said display face extending through an aperture of said secondary shielding means, said secondary shielding means comprising:
• enclosure means for enclosing said CRT, said CRT having an internal conductive layer associated with said display face and conductively coupled to said enclosure means;
• means for grounding said internal conductive layer coupled to said enclosure means;
• and
• primary shielding means internal to said secondary shielding means having at least one portion coaxial with said neck portion of said CRT for inhibiting electromagnetic emissions from said CRT, whereby electromagnetic emissions through said display face and said aperture of said secondary shielding means are reduced.

A shielded CRT, comprising:

• a CRT;
• video circuitry coupled to at least one cathode positioned in a neck portion of said CRT, said cathode ray tube further including at least two anodes, a non-shielded display face, deflection means for deflecting electrons accelerated by said anode means to said display face, and an internal conducive layer associated with said display face;
• primary shielding means surrounding said video circuitry having at least one portion coaxial with said neck portion for inhibiting electromagnetic emissions therefrom;
• and
• secondary shielding means for enclosing said primary shielding means and said cathode ray tube and for inhibiting electromagnetic emission therefrom said non-shielded display face extending through an aperture in said secondary shielding means, said secondary shielding means including means for conductively coupling said internal conductive layer of said CRT to said secondary shielding means via a reactive path to ground, whereby electromagnetic emissions through said aperture of said secondary shielding means are reduced.

A method for shielding the RF emissions from a CRT, comprising the steps of:

• providing a conductive layer internal of said CRT associated with a face portion of said CRT;
• enclosing said CRT within a shielded enclosure, said face portion of said CRT extending through an aperture of said shielded enclosure;
• conductively coupling said conductive layer to said shield enclosure;
• and
• grounding said conductive layer coupled to said shielded enclosure via a reactive path.

A method for shielding the RF emissions from a CRT having a neck portion and a conductive layer internal of said CRT associated with a face portion, comprising the steps of:

• providing a waveguide coaxial with said neck portion for suppressing electromagnetic emissions therefrom;
• enclosing said CRT and said waveguide within a shielded enclosure, said face portion of said CRT extending through an aperture of said shielded enclosure;
• conductively coupling said conductive layer to said shielded enclosure;
• and
• grounding said conductive layer coupled to said shielded enclosure.