Self-convergent electron gun system

For use in a color cathode ray tube system having a color tube with a phosphor screen, the system comprising:

• a three-beam inline electron gun for exciting said screen, said gun including:
• cathode means and focus lens means for developing a center beam and two outer beams and for forming three focused electron beam spots at the screen of the tube, said focus lens means being so constructed and arranged such that changes in focusing field strength alter beam convergence;
• convergence means for converging said electron beams, said convergence means including electrode means having outer beam apertures shaped to create field-strength-dependent asymmetrical outer beam fields effective to at least partially converge said beams;
• and
• system signal generating means for developing a signal having amplitude variations correlated with the scan of the beams across the screen and for applying said signal to said focus lens means to cause the strength of said common focusing field to vary to produce dynamic focus and therewith a first dynamic convergence effect, and for applying said signal to said convergence lens means to produce a second dynamic convergence effect which adds to said first dynamic convergence effect.

For use in a color cathode ray tube system having a color tube with a phosphor screen, the system comprising:

• a three-beam, inline electron gun for exciting said screen, said gun including:
• cathode means and focus lens means for developing a center beam and two outer beams and forming three focused electron beam spots at the screen of the tube, and
• electrostatic quadrupole-developing means configured and arranged to develop a horizontally unbalanced quadrupole field in the path of each of said outer beams when appropriately excited;
• and
• system signal generating means for developing a signal having amplitude variations correlated with the scan of the beams across the screen and for applying said signal to said quadrupole developing means to produce a dynamic convergence effect on said beams.

For use in a color cathode ray tube system having a color tube with a phosphor screen, the system comprising:

• a three-beam, inline gun for exciting said screen, said gun including:
• cathode means and focus lens means for developing a center beam and two outer beams and for forming three focused electron beam spots at the screen of the tube, said focus lens means being constructed and arranged such that changes in focusing field strength alter beam convergence, and
• electrostatic quadrupole-developing means configured and arranged to develop a horizontally unbalanced quadrupole field in the path of each of said outer beams when appropriately excited;
• and
• system signal generating means for developing a signal having amplitude variations correlated with the scan of the beams across the screen and for applying said signal to said focus lens means to cause the strength of said common focusing field to vary to produce dynamic focus and therewith a first dynamic convergence effect, and for applying said signal to said electrostatic quadrupole-developing means to produce a second dynamic convergence effect which adds to said first dynamic convergence effect.

For use in a color cathode ray tube system having a three-beam color tube with a phosphor screen, the system comprising:

• partially self-converging yoke means for deflecting said beams, said yoke means partially but incompletely self-converging the three beams, said yoke means introducing a quadrupole field which undesirably astigmatizes said beams;
• a three-beam inline electron gun for exciting said screen, said gun including:
• cathode means and focus lens means for developing a center beam and two outer beams and for forming three focus electron beam spots at the screen of the tube, said focus lens means forming a common main focusing field for all three of said beams which causes said outer beams to converge as a function of the strength of said main focusing lens field;
• convergence means for converging said electron beams, comprising at least two facing electrodes, a first electrode being adapted to receive a relatively higher excitation potential and a second electrode a relatively lower excitation potential, at least one of said electrodes having a center aperture and two outer apertures arranged in a line along an electrode axis or orthogonal to the gun axis, said outer apertures having profile distortions which are symmetrical about said electrode axis and a vertical axis through the center aperture, but asymmetrical about respective vertical axes through the outer apertures;
• and
• system signal generating means for developing a signal having amplitude variations correlated with the scan of the beams across the screen and for applying said signal to said focus lens means to cause the strength of said common focusing field to vary to produce dynamic focus and therewith a first partial dynamic convergence effect, and to said convergence means to produce a second partial dynamic convergence effect, the dynamic convergence effects of said yoke means, said focus lens means, and said convergence means combining additively.

For use in a color cathode ray tube system having a three-beam color tube with a phosphor screen, the system comprising:

• partially self-converging yoke means for deflecting said beams, said yoke means partially but incompletely self-converging the three beams;
• said yoke means introducing a quadrupole field which undesirably astigmatizes said beams;
• a three-beam, inline electron gun for exciting said screen, said gun including:
• cathode means and focus lens means for developing a center beam and two outer beams and forming three focused electron beam spots at the screen of the tube, and
• electrostatic quadrupole-developing means configured and arranged to develop a horizontally unbalanced quadrupole field in the path of each of said outer beams when appropriately excited;
• and
• system signal generating means for developing a signal having amplitude variations correlated with the scan of the beams across the screen and for applying said signal to said quadrupole developing means to produce a partial dynamic convergence effect on said beams, said dynamic convergence effect combining additively with the self-convergence produced by said yoke means.

For use in a color cathode ray tube system having a color tube with a phosphor screen, the system comprising:

• partially self-converging yoke means for deflecting said beams, said yoke means partially but incompletely self-converging the three beams, said yoke means introducing a quadrupole field which undesirably astigmatizes said beams;
• a three-beam, inline gun for exciting said screen, said gun including:
• cathode means and focus lens means for developing a center beam and two outer beams and for forming three focused electron beam spots at the screen of the tube, said focus lens means forming a common main focusing field for all three of said beams which causes said outer beams to converge and deconverge as a function of the strength of said common main focusing lens field, and
• electrostatic quadrupole-developing means configured and arranged to develop a horizontally unbalanced quadrupole field in the path of each of said outer beams when appropriately excited;
• and
• system signal generating means for developing a signal having amplitude variations correlated with the scan of the beams across the screen and for applying said signal to said focus lens means to cause the strength of said common focusing field to vary to produce dynamic focus and therewith a first partial dynamic convergence effect, and for applying said signal to said electrostatic quadrupole-developing means to produce a second partial dynamic convergence effect, the dynamic convergence effects of said yoke means, said focus lens means, and said quadrupole-developing means combining additively.

For use in a color cathode ray tube system having a color tube with a phosphor screen, the system comprising:

• self-convergent yoke means for deflecting said beams in a converging manner on the screen, said yoke means introducing a beam-astigmatizing quadrupole field;
• a three-beam, inline electron gun for exciting said screen, said gun including:
• means including cathode means for developing said beams;
• three focus lens means for receiving said electron beams and forming three focused electron beam spots at the screen of the tube, said focus lens means each having a plurality of electrode means spaced along a lens axis parallel to a gun central axis, wherein at least two of said electron beams are off-axis with respect to said gun central axis;
• convergence means effective to converge the off-axis beams when appropriately excited, said convergence means including beam bending means for producing an asymmetrical field in the path of said beam for diverting said beam from a straight line path, comprising at least two facing electrodes adapted to receive different excitation potentials and having coaxial beam-passing openings, at least one of said openings being symmetrical about a first electrode axis but asymmetrical about an orthogonal second electrode axis to thereby produce said asymmetrical field;
• means for developing and applying to said electrode means of said focus lens means potentials which form one or more focusing field components between said electrode means;
• and
• system signal generating means for developing a signal having amplitude variations correlated with a scan of the beams across the screen and for applying said signal to at least one of said electrode means and to said convergence means, to simultaneously cause, as a function of beam deflection angle, (1) the strength of said one or more focusing field components to weaken to produce a dynamic focusing effect, and (2) the strength of said asymmetrical field component affecting said off-axis beams to weaken to produce a dynamic convergence effect;
• whereby the application of said signal, in addition to adjusting the focus of the beams and compensating for the astigmatizing effect of said yoke, provides an additional measure of beam convergence to reduce the self-convergence demands on the yoke.

An electron gun system for use in a color cathode ray tube having a screen and comprising:

• means including cathode means for developing three electron beams;
• three focus lens means for receiving said electron beams and forming three focused electron beam spots at the screen of the tube, said focus lens means each having first and second electrode means spaced along a lens axis parallel to the other lens axes and parallel to a gun central axis, at least two of which lens axes are off-axis with respect to said gun central axis;
• means for developing and applying to said electrode means of each of said focus lens means potentials which form one or more focusing field components between said electrode means, wherein said first electrode means is maintained at a lower potential than said second electrode means;
• said off-axis focus lens means each being so structured and arranged as to cause a focusing field component to be asymmetrical and effective to statically converge the off-axis beams, wherein said off-axis focus lens means each includes an aperture in said first electrode through which a respective electron beam is directed having a notch therein extending outwardly away from said gun central axis;
• and
• signal generating means for developing a signal having amplitude variations correlated with a scan of the beams across the screen and for applying said signal to at least one of said electrode means to simultaneously cause, as a function of beam angle, the strength of said asymmetrical field component affecting said off-axis beams to weaken to produce a dynamic convergence effect.

An electron gun system for use in a color cathode ray tube having a screen and comprising:

• means including cathode means for developing three electron beams;
• three focus lens means for receiving said electron beams and forming three focused electron beam spots at the screen of the tube, said focus lens means each having a plurality of electrode means spaced along a lens axis parallel to the other lens axes and parallel to a gun central axis, at least two of which lens axes are off-axis with respect to said gun central axis;
• means for developing and applying to said electrode means of each of said focus lens means potentials which form one or more focusing field components between said electrode means;
• said off-axis focus lens means each being so structured and arranged as to cause a focusing field component to be asymmetrical and effective to converge the off-axis beams, each of said off-axis focus lens means including beam bending means for producing asymmetrical fields in the paths of said outer beams for diverting said outer beams from respective straight line paths toward a common point of convergence, comprising at least two facing electrodes, a first electrode being adapted to receive a relatively higher excitation potential and a second electrode a relatively lower excitation potential, wherein one of said electrodes includes a center opening and two outer beam-passing openings arranged in line along an electrode horizontal axis orthogonal to the gun axis, said outer openings having opening distortions which are symmetrical about said electrode horizontal axis and a vertical axis through the center opening, but asymmetrical about respective vertical axes through the outer openings to thereby produce said asymmetrical fields for said outer beams;
• and
• signal generating means for developing a signal having amplitude variations correlated with a scan of the beams across the screen and for applying said signal to at least one of said electrode means to simultaneously cause, as a function of beam deflection angle, (1) the strength of said one or more focusing field components to weaken to produce a dynamic focusing effect, and (2) the strength of said asymmetrical field component affecting said off-axis beams to weaken to produce a dynamic convergence effect;
• whereby said gun system provides control of convergence and focus with a single dynamic signal.

An electron gun system for use in a color cathode ray tube having a screen and comprising:

• means including cathode means for developing three electron beams;
• three focus lens means for receiving said electron beams and forming three focused electron beam spots at the screen of the tube, said focus lens means each having a plurality of electrode means spaced along a lens axis parallel to the other lens axes and parallel to a gun central axis, at least two of which lens axes are off-axis with respect to said gun central axis;
• means for developing and applying to said electrode means of each of said focus lens means potentials which form one or more focusing field components between said electrode means;
• said off-axis focus lens means each including an outer beam-passing opening so structured and arranged as to cause a focusing field component to be asymmetrical and effective to statically converge the off-axis beams, said outer openings having profile distortions which are symmetrical about said electrode axis and a vertical axis through the center opening, but asymmetrical about respective vertical axes through the outer openigns, said profile distortions each taking the form of an outwardly extending opening enlargement;
• and
• signal-generating means for developing a signal having amplitude variations correlated with a scan of the beams across the screen and for applying said signal to at least one of said electrode means, and to said convergence means to simultaneously cause, as a function of beam deflection angle, (1) the strength of said one or more focusing field components to weaken to produce a dynamic focusing effect, and (2) the strength of said asymmetrical field component affecting said off-axis beams to weaken to produce a dynamic convergence effect, whereby said gun system provides control of convergence and focus with a single dynamic signal.

An electron gun system for use in a color cathode ray tube having a screen and comprising:

• means including cathode means for developing three electron beams;
• three focus lens means for receiving said electron beams and forming three focused electron beam spots at the screen of the tube, said focus lens means each having a plurality of electrode means spaced along a lens axis parallel to the other lens axes and parallel to a gun central axis, at least two of which lens axes are off-axis with respect to said gun central axis;
• means for developing and applying to said electrode means of each of said focus lens means potentials which form one or more focusing field components between said electrode means;
• said off-axis focus lens means each being so structured and arranged as to cause a focusing field component to be asymmetrical and effective to converge the off-axis beams;
• each of said focus lens means including first and second quadrupole-developing electrode means located in a substantially focus-field-free region therewithin and so configured and arranged as to develop a quadrupolar field in the path of each of said beams when a voltage difference is established therebetween, wherein said electrode means includes first, center and third electrodes and wherein said center electrode is adapted to receive a lower potential than said first and third electrodes, and wherein said center electrode has a center opening and two outer openings arranged in a line along an electrode axis orthogonal to the gun axis, said outer openings having profile distortions in the form of outwardly directed notches which are symmetrical about said electrode axis and a vertical axis through the center opening, but asymmetrical about respective vertical axes through the outer openings;
• and
• signal-generating means for developing a signal having amplitude variations correlated with a scan of the beams across the screen and for applying said signal to at least one of said electrode means, to said convergence means, and to said quadrupole-developing means to simultaneously cause, as a function of beam deflection angle, (1) the strength of said one or more focusing field components to weaken to produce a dynamic focusing effect, (2) the strength of said asymmetrical field component affecting said off-axis beams to weaken to produce a dynamic convergence effect, and (3) the strength of said quadrupolar field to increase to produce a dynamic astigmatism-correction effect.

For use in a color cathode ray tube (CRT) wherein first, second and third inline electron beams are directed onto a phosphorescing screen in the CRT, with said second beam disposed intermediate said first and third beams, an electron gun comprising:

• cathode means for generating electrons;
• crossover means for receiving electrons from said cathode means and for forming a beam crossover;
• first focusing means driven by a dynamic voltage for focusing the inline electron beams on the phosphorescing screen, wherein a misconvergence is present among the electron beams on the phosphorescing screen;
• and
• second focusing means disposed adjacent to said first focusing means for displacing the first and third electron beams horizontally away from the second beam for reducing said misconvergence and bringing said electron beams into convergence near the lateral portions of the phosphorescing screen, wherein said second focusing means is maintained at a lower voltage than said first focusing means when the electron beams are off-center on the screen and includes first and third outer apertures and a second middle aperture through which respective ones of the electron beams are directed, and wherein said first and third outer apertures each include an outwardly directed notch.

An electron gun system for use in a color cathode ray tube having a screen and comprising:

• means including cathode means for developing three electron beams;
• three focus lens means for receiving said electron beams and forming three focused electron beam spots at the screen of the tube, said focus lens means each having first and second electrode means spaced along a lens axis parallel to the other lens axes and parallel to a gun central axis, at least two of which lens axes are off-axis with respect to said gun central axis;
• means for developing and applying to said electrode means of each of said focus lens means potentials which form one or more focusing field components between said electrode means, wherein said first electrode means is maintained at a lower potential than said second electrode means;
• said off-axis focus lens means each being so structured and arranged as to cause a focusing field component to be asymmetrical and effective to converge the off-axis beams, each of said off-axis focus lens means including beam bending means for producing asymmetrical fields in the paths of said outer beams for diverting said outer beams from respective straight line paths toward a common point of convergence, comprising at least two facing electrodes, a first electrode being adapted to receive a relatively higher excitation potential and a second electrode a relatively lower excitation potential, wherein one of said electrodes includes a center opening and two outer beam-passing openings arranged in line along an electrode horizontal axis orthogonal to the gun axis, said outer openings having opening distortions which are symmetrical about said electrode horizontal axis and a vertical axis through the center opening, but asymmetrical about respective vertical axes through the outer openings to thereby produce said asymmetrical fields for said outer beams;
• and
• signal generating means for developing a signal having amplitude variations correlated with a scan of the beams across the screen and for applying said signal to at least one of said electrode means to simultaneously cause, as a function of beam angle, the strength of said asymmetrical field component affecting said off-axis beams to weaken to produce a dynamic convergence effect.