Multi-mode, hybrid-type CRT and electron gun therefor with selectable different sized grid apertures

An electron gun for a multi-mode color cathode ray tube (CRT) including a display screen whereon a video image is formed by sweeping a plurality of horizontally aligned electron beams over a plurality of vertically spaced, horizontal scan lines in a raster-like manner, wherein each electron beam provides one of the three primary colors of red, green or blue of the video image, said electron gun comprising:

• cathode means for providing energetic electrons;
• a beam forming region (BFR) disposed adjacent to said cathode means and including first and second spaced, charged grids, said beam forming region further including:
• first beam forming means for forming said energetic electrons into a first plurality of horizontally aligned, spaced electron beams providing the three primary colors of red, green and blue, wherein each of said first plurality of electron beams has a cross-section A.sub.1 when the CRT is used as a television receiver;
• and
• second beam forming means for forming said energetic electrons in a second plurality of horizontally aligned, spaced electron beams providing the three primary colors of red, green and blue, wherein each of said second plurality of electron beams has a cross-section A.sub.2 when the CRT is used as a high resolution video monitor, where A.sub.1 >A.sub.2 ;
• said BFR further including a G1 control grid and a G2 screen grid each having first and second pluralities of horizontally aligned, vertically spaced beam passing apertures, wherein each of said first plurality of apertures has a diameter D.sub.1 and each of said second plurality of apertures has a diameter of D.sub.2, and wherein said first plurality of apertures forms said first electron beams and said second plurality of apertures forms said second electron beams, with D.sub.1 >D.sub.2 ;
• switch means coupled to said first and second beam forming means for allowing a user to select either a television receiver mode of operation or a high resolution video monitor mode of operation;
• lens means disposed intermediate said BFR and the CRT's display screen for focusing the electron beams on the display screen;
• and
• convergence means disposed intermediate said lens means and the display screen for converging said first and second pluralities of horizontally aligned, spaced electron beams into first and second spots on the display screen.

An electron gun for use in a multi-mode cathode ray tube (CRT) including a display screen whereon a video image is formed by sweeping electron beams over a plurality of vertically spaced, horizontal scan lines in a raster-like manner, said electron gun comprising:

• first and second cathode means for respectively providing first and second pluralities of energetic electrons;
• a beam forming region including first and second spaced, charged grids disposed adjacent said cathode means and further including:
• first beam forming means aligned with said first cathode means for forming said first plurality of energetic electrons into a first beam having a cross-section A.sub.1 when the CRT is used as a television receiver;
• and
• second beam forming means aligned with said second cathode means for forming said second plurality of energetic electrons into a second beam having a cross-section A.sub.2 when the CRT is used as a high resolution video monitor, where A.sub.1 >A.sub.2 ;
• Switch means coupled to said first and second cathode means for allowing a user to select either said first plurality of energetic electrons or said second plurality of energetic electrons for operating the CRT either as a television receiver or as a high resolution video monitor, respectively;
• and
• lens means disposed intermediate said BFR and the CRT's display screen for focusing either said first beam or said second beam on the display screen.