Color tube having shadow mask lens electrode

Claim 2

A cathode-ray tube for a color television comprising: an evacuated envelope; a triad-type fluorescent screen in contact with a conductive layer positioned at one end of said envelope; an electron beam source positioned adjacent to the other end of said envelope; an anode electrode positioned between said electron beam source and said fluorescent screen and being connected to said conductive layer; a shadow mask with circular holes positioned between said electron beam source and said anode screen, each of said holes being aligned with a triad of said screen adjacent to said screen; a shadow mask lens electrode having apertures and being positioned between said shadow mask and said screen closer to said shadow mask than to said screen, the portions of said shadow mask lEns electrode defined by the axially projected images of the respective holes of said shadow mask thereon providing an electrically conductive part of said shadow mask lens electrode at least in the center of these portions; and means supplying to said shadow mask lens electrode and said screen the same DC voltage and supplying to said shadow mask a DC voltage slightly lower than that applied to said shadow mask lens electrode, whereby said electron beam can be focused throughout each hole in said shadow mask by an electric field produced between said shadow mask and shadow mask lens electrode.

Claim 3

A cathode-ray tube as defined in claim 1, wherein said shadow mask lens electrode has a plurality of apertures each being out of registration and each only partially overlapping with the axially projected image of any one hole of said shadow mask.

Claim 4

A cathode-ray tube as defined in claim 2, wherein said apertures of said shadow mask lens electrode are positioned at a vertex of a regular polygon the center of which is on the axis of a hole of said shadow mask.

Claim 5

A cathode-ray tube as defined in claim 3, wherein said portions of said shadow mask lens electrode further include holes positioned between, and of smaller diameter than, said apertures in the shadow mask lens electrode.

Claim 6

A cathode-ray tube as defined in claim 2, wherein said shadow mask lens electrode has approximately the same number of apertures as the number of holes in said shadow mask, said apertures being larger than the holes of said shadow mask.

Claim 7

A cathode-ray tube for a color television comprising; an evacuated envelope; a triad-type fluorescent screen in contact with a conductive layer positioned at one end of said envelope; an electron beam source positioned adjacent to the other end of said envelope; an anode electrode positioned between said electron beam source and said fluorescent screen and being connected to said conductive layer; a shadow mask having holes and being positioned between said electron beam source and said screen, each of said holes being aligned with a triad of said screen adjacent to said screen; a shadow mask lens electrode positioned between said screen and said shadow mask adjacent to said shadow mask, said shadow mask lens electrode being formed as a conductive structure having apertures, said shadow mask and said shadow mask lens electrode being arranged with the conductive part of said shadow mask lens electrode positioned at least at the locations of the centers of the electron beam paths through the respective holes of said shadow mask; and means supplying to said shadow mask lens electrode and said screen the same DC voltage and for supplying to said shadow mask a DC voltage slightly lower than that applied to said shadow mask lens electrode, whereby said electron beam can be focused throughout each hole in said shadow mask by an electric field produced between said shadow mask and said shadow mask lens electrode.

Claim 8

A cathode-ray tube for a color television comprising; an evacuated envelope; a triad-type fluorescent screen in contact with a conductive layer positioned at one end of said envelope; an electron beam source positioned adjacent to the other end of said envelope; an anode electrode positioned between said electron beam source and said fluorescent screen and being connected to said conductive layer; a shadow mask having holes and being positioned between said electron beam source and said screen, each of said holes being aligned with a triad of said screen adjacent to said screen; a shadow mask lens electrode positioned between said screen and said shadow mask adjacent to said shadow mask, said shadow mask lens electrode being formed as a conductive structure having apertures, said shadow mask and said shadow mask lens electrode being arranged with the conductive part of said shadow mask lens electrode positioned at least at the locations of the centers of the electron beam paths through the respective holes of said shadow mask; and means supplying to said shadow mask lens electrode and said screen the same DC voltage and for supplying to said shadow mask a DC voltage slightly lower than that applied to said shadow mask lens electrode, whereby said electron beam can be focused throughout each hole in said shadow mask by an electric field produced between said shadow mask and said shadow mask lens electrode.

Claim 9

A cathode-ray tube for a color television of claim 6, of which said shadow mask lens electrode is formed of a solid conductive plate with holes.

Claim 10

A cathode-ray tube for a color television of claim 7, in which said conductive plate with holes has a plurality of holes, each hole being out of registration and at least partially overlapping with the axially projected image of a hole of said shadow mask, said hole of said conductive plate being located at a vertex of a regular polygon the center of which is on the axis of a hole of said shadow mask.

Claim 11

A cathode-ray tube for a color television of claim 8, of which said conductive plate with holes has approximately the same number of holes as the number of holes of said shadow mask, said holes of said conductive plate being larger than the holes of said shadow mask.

Claim 12

A cathode-ray tube for a color television as defined in claim 6, wherein said shadow mask lens electrode further includes in said conductive structure between the apertures additional holes greatly Smaller than said apertures.

Claim 13

A cathode-ray for a color television as defined in claim 6, of which said shadow mask lens electrode is made of a fine mesh.

Claim 14

A cathode-ray tube for a color television comprising: an evacuated envelope; a triad-type fluorescent screen in contact with a conductive layer positioned at one end of said envelope; an electron beam source positioned adjacent to the other end of said envelope; an anode electrode positioned between said electron beam source and said fluorescent screen and being connected to said conductive layer; a shadow mask with circular holes positioned between said electron beam source and said screen, each of said holes being aligned with a triad of said screen adjacent to said screen; a shadow mask lens electrode in the form of a solid conductive plate having a plurality of holes therein positioned between said shadow mask and said screen closely adjacent to said shadow mask; the holes in said conductive plate being larger than the holes in said shadow mask and being out of registration and at least partially overlapping with the axially projected image of a hole of said shadow mask to provide a conductive electron barrier at least at the locations of the centers of the electron beam paths through the respective holes of said shadow mask; and means supplying to said shadow mask lens electrode and said screen the same DC voltage and for supplying to said shadow mask a DC voltage slightly lower than that applied to said shadow mask lens electrode, whereby said electron beam can be focused throughout each hole in said shadow mask by an electric field produced between said shadow mask and said shadow mask lens electrode.

Claim 15

A cathode-ray tube for a color television comprising: an evacuated envelope; a triad-type fluorescent screen in contact with a conductive layer positioned at one end of said envelope; an electron beam source positioned adjacent to the other end of said envelope; an anode electrode positioned between said electron beam source and said fluorescent screen and being connected to said conductive layer; a shadow mask with circular holes positioned between said electron beam source and said screen, each of said holes being aligned with a triad of said screen adjacent to said screen; a shadow mask lens electrode in the form of a solid conductive plate having a plurality of holes therein positioned between said shadow mask and said screen closely adjacent to said shadow mask; the holes in said conductive plate being larger than the holes in said shadow mask and being out of registration and at least partially overlapping with the axially projected image of a hole of said shadow mask to provide a conductive electron barrier at least at the locations of the centers of the electron beam paths through the respective holes of said shadow mask; and means supplying to said shadow mask lens electrode and said screen the same DC voltage and for supplying to said shadow mask a DC voltage slightly lower than that applied to said shadow mask lens electrode, whereby said electron beam can be focused throughout each hole in said shadow mask by an electric field produced between said shadow mask and said shadow mask lens electrode.

Claim 16

A cathode-ray tube as defined in claim 12, wherein said shadow mask lens electrode includes additional holes smaller than the other holes in said shadow mask lens electrode and the holes in said shadow mask, said additional holes being provided in the portion of the shadow mask lens electrode forming said conductive electron barriers at the locations of the centers of the electron beam paths through the respective holes of said shadow mask.