Color display system

In a color display system including a cathode-ray tube having an electron gun for generating and directing three electron beams along paths toward a screen of said tube, said gun including electrodes comprising a beam-forming region and electrodes for forming a main focusing lens, and said system including a self-converging yoke that produces an astigmatic magnetic deflection field, the improvement comprising

• electrodes in said electron gun for forming a multipole lens between the beam-forming region and the main focusing lens in each of the electron beam paths, wherein each multipole lens is oriented to provide a correction to an associated electron beam to at least partially compensate for the effect of the astigmatic magnetic deflection field on the associated beam, and wherein said electrodes for forming a multipole lens include a first multipole lens electrode and a second multipole lens electrode, said second multipole lens electrode being a portion of one of said electrodes for forming a main focusing lens, and said first multipole lens electrode being located between the second multipole lens electrode and the beam-forming region, adjacent to the second multipole lens electrode,
• means for applying a fixed focus voltage to said second multipole lens electrode,
• means for applying a dynamic voltage signal to said first multipole lens electrode, said dynamic voltage signal being related to deflection of the electron beams, and
• said multipole lens being located sufficiently close to said main focusing lens to effectively couple the dynamic voltage signal applied to the first multipole lens electrode to the second multipole lens electrode,
• whereby the focus voltage on the second multipole lens electrode is effectively varied, although not actually varied, with voltage variation in the dynamic voltage signal.

In a color display system including a cathode-ray tube having an electron gun for generating and directing three electron beams along paths toward a screen of said tube, said gun including electrodes comprising a beam-forming region and electrodes for forming a main focusing lens, and said system including a self-converging yoke that produces an astigmatic magnetic deflection field, the improvement comprising

• electrodes in said electron gun for forming a multipole lens between the beam-forming region and the main focusing lens in each of the electron beam paths, wherein each multipole lens is oriented to provide a correction to an associated electron beam to at least partially compensate for the effect of the astigmatic magnetic deflection field on the associated beam, and wherein said electrodes for forming a multipole lens include a first multipole lens electrode and a second multipole lens electrode, said second multipole lens electrode being a portion of one of said electrodes for forming a main focusing lens, and said first multipole lens electrode being located between the second multipole lens electrode and the beam-forming region, adjacent to the second multipole lens electrode,
• means for applying a fixed focus voltage to said second multipole lens electrode,
• means for applying a dynamic voltage signal to said first multipole lens electrode, said dynamic voltage signal being related to deflection of the electron beams, and
• each multipole lens being located sufficiently close to said main focusing lens to affect the strength of said main focusing lens as the voltage on the first multipole lens electrode is varied.

In a color display system including a cathode-ray tube having an electron gun for generating and directing three electron beams along paths toward a screen of said tube, said gun including electrodes comprising a beam-forming region and electrodes for forming a main focusing lens, and said system including a self-converging yoke that produces an astigmatic magnetic deflection field, the improvement comprising

• electrodes in said electron gun for forming a multipole lens between the beam-forming region and the main focusing lens in each of the electron beam paths, wherein each multipole lens is oriented to provide a correction to an associated electron beam to at least partially compensate for the effect of the astigmatic magnetic deflection field on the associated beam, and wherein said electrodes for forming a multipole lens include a first multipole lens electrode and a second multipole lens electrode, said second multipole lens electrode being a portion of one of said electrodes for forming a main focusing lens, and said first multipole lens electrode being located between the second multipole lens electrode and the beam-forming region, adjacent to the second multipole lens electrode,
• means for applying a fixed focus voltage to said second multipole lens electrode,
• means for applying a dynamic voltage signal to said first multipole lens electrode, said dynamic voltage signal being related to deflection of the electron beams, and
• said multipole lens being formed by facing interdigitated portions of said first and second multipole electrodes, the interdigitated portion of said second multipole lens electrode being extrusions about apertures of the second multipole lens electrode that form a portion of the main focusing lens.

In a color display system including a cathode-ray tube having an electron gun for generating and directing three inline electron beams along paths toward a screen of said tube, said gun including electrodes comprising a beam-forming region and electrodes for forming a main focusing lens, and said system including a self-converging yoke that produces an astigmatic magnetic deflection field, the improvement comprising

• said electron gun including three inline cathodes and six electrodes designated G1, G2, G3, G4, G5 and G6 spaced from said cathodes in the order named, said cathodes, G1, G2 and a portion of said G3 facing the G2 comprising said beam-forming region and said G5 and G6 forming said main focusing lens,
• said G4 and G5 electrodes forming a multipole lens in each of the electron beam paths, wherein each multipole lens is oriented to provide a correction to an associated electron beam to at least partially compensate for the effect of the astigmatic magnetic deflection field on the associated beam,
• means for applying a fixed focus voltage to said G3 and G5 electrodes,
• means for applying a dynamic voltage signal to said G4 electrode, said dynamic voltage signal being related to deflection of the electron beams,
• each multipole lens being located sufficiently close to the main focusing lens to cause the strength of the main focusing lens to decrease with increase in voltage of said dynamic voltage signal.