Patent ID: 6455993
Filing Date: 2002-09-24
Classification: H01J

Abstract:
A shadow mask type color cathode ray tube, comprising:an envelope including a panel portion with a face plate, a neck portion, and a funnel portion which connects the panel portion with the neck portion, a fluorescent screen in the face plate, an electron gun in the neck portion, a deflection yoke fixed on the funnel portion, a shadow mask placed so as to face the fluorescent screen in the panel portion, onto which an original plate with a substantially rectangular porous portion is pressed and shaped, the porous portion establishing many electron beam passage holes, and the diameter of the electron beam passage holes being smaller in corner regions of the porous portion than in a center region of the porous portion, wherein a first range of substantially quadrangular state is a range surrounded by four points, (1) a corner edge Pc of porous portion, (2) a reference point P0 which left along the diagonal line direction of porous portion from the corner edge Pc, (3) a horizontal peripheral line edge P0H of reverse direction for perpendicular center line of porous portion from reference point P0 horizontally, (4) a perpendicular peripheral line edge P0V of reverse direction for horizontal center line of porous portion from reference point P0 perpendicularly, wherein a diameter of electron beam passage hole in said first range have equation D1=D0âˆ’{A1Ã—(X2+Y2)}1.5 D0 is diameter of electron beam passage hole which is the nearest to reference point P0, X is horizontal distance which approaches to horizontal peripheral line edge P0H from reference point P0, Y is vertical distance which approaches to perpendicular peripheral line edge P0V from reference point P0, D1 is diameter of electron beam passage hole in arbitrary position ,in first range of quadrangular state substantially, A1 is constant.