Cathode-ray tube
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsShin-ichiro Hatta, Ryuichi Murai, Hiroshi Iwamoto, Shigeo Nakatera, Masaki Kawasaki
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Abstract
In the structure of the present invention, there can be provided a cathode ray tube in which deviation in the trajectory of the electron beams by the leakage magnetic field from the mask frame (1) is decreased by using a polygonal mask frame (1) in which the relative magnetic permeability of longer side members (31) out of two side members adjacent to each other at the joint portion of the mask frame (1) is the same as or larger than the relative magnetic permeability of the other side members (21). Thus, the significance of the present invention in industrial terms is large.
Claims15
A cathode ray tube comprising:
- a bulb whose inside volume is maintained in vacuum;
- an electron gun located inside of said bulb for ejecting electron beams;
- a fluorescent material located on an inside wall of said bulb, for emitting light when electron beams ejected from said electron gun are applied thereto;
- beam deflection means for deflecting such electron beams to scan the surface of said fluorescent material;
- an inner magnetic shield located inside said bulb for decreasing the deviation of the trajectory of electron beams deflected by the beam deflection means in an external magnetic field;
- a shadow mask arranged in front of an inside surface of said fluorescent material;
- and
- a polygon-shaped mask frame for fixing said shadow mask, the frame comprising a side member for each side of said frame and a joint portion for joining adjacent side members, wherein the adjacent side members connected by each joint portion satisfy the following condition:
- μr,1>μr,s>1
- where μr,1 represents a relative magnetic permeability of a longer side member and μr,s represents a relative magnetic permeability of the other member.
Dependencies are inferred from the claim text.