Patent ID: 6608454
Filing Date: 2003-08-19
Classification: H01J

Abstract:
A color cathode ray tube comprising:a vacuum envelope including a substantially rectangular panel having a substantially flat outer surface, an inner surface provided with a phosphor screen, and a long axis and a short axis perpendicular to each other and also to a tube axis; a shadow mask arranged in the vacuum envelope and opposed to the phosphor screen, the shadow mask including a mask main body that has a substantially rectangular mask surface and a skirt portion extending along a periphery of the mask surface, and a substantially rectangular mask frame attached to the skirt section of the mask main body, the mask surface including an effective portion opposed to the phosphor screen and provided with a plurality of electron beam passage apertures; and an electron gun provided in the vacuum envelope for emitting electron beams onto the phosphor screen through the shadow mask, wherein: the inner surface of the panel has an effective section with a curvature, the inner surface of the panel being formed to satisfy at least one of the following relationships: ZPH/LPH&lE;0.050, andZPV/LPV&lE;0.050 where LPH represents a distance from a center of the effective section to a long axis end of the effective section, LPV represents a distance from the center of the effective section to a short axis end of the effective section, ZPH represents a fall of the effective section at the long axis end along the tube axis with respect to a level of the center of the effective section, and ZPV presents a fall of the effective section at the short axis end along the tube axis with respect to the level of the center of the effective section; andthe mask surface has a pair of long sides situated symmetrical with respect to the long axis, and a pair of short sides situated symmetrical with respect to the short axis, at least one of each long side and each short side being curved such that a central portion thereof projects outwardly, and satisfying at least corresponding one of the following relationships: YML/LML&lE;0.015, andXMS/LMS&lE;0.015 where LML represents a distance from the short axis of the effective portion of the mask surface to each corner of the effective portion, LMS represents a distance from the long axis of the effective portion of the mask surface to each corner of the effective portion, YML represents a fall, along the short axis, between a point of each long side of the mask surface on the short axis and a point of said each long side which is apart from the short axis by LML, and XMS represents a fall, along the long axis, between a point of each short side of the mask surface on the long axis and a point of said each short side which is apart from the long axis by LMS.