Patent ID: 6720723
Filing Date: 2004-04-13
Classification: H01J

Abstract:
A cathode ray tube comprising:a face plate having a phosphor screen on an inner main surface thereof; an electron gun operable to emit an electron beam toward the phosphor screen; a frame that holds a mask at a place between the electron gun and the inner main surface and closet to the inner main surface, so that the mask is substantially in parallel with the inner main surface; and an internal magnetic shield that is a pyramid having two openings respectively at an apex and a bottom of the pyramid, has two opposite long sides and two opposite short sides, and is deposited to surround a path of the electron beam with the apex of the pyramid being on a side of the electron gun, wherein an end of the internal magnetic shield being the bottom of the pyramid is attached, inside the cathode ray tube, to the frame, and two corners of each long side are cut to extend the opening on the side of the electron gun, wherein a length of each cut along an edge of each long side demarking the opening on the side of the electron gun is less than half of a length of the edge.