Color cathode ray tube with temperature-responsive color purity magnets

Claim 1

A color cathode ray tube arrangement comprising: A. a color cathode ray tube comprising: 1. a color phosphor screen comprising areas arranged in a predetermined pattern to emit light of different colors when struck by electrons, 2. electron beam generating means to direct electron beams at said screen, and 3. a beam selecting element disposed near said screen comprising electron passages positioned relative to said areas to allow said eLectron beams to land on predetermined areas of said screen according to the directions along which said beams pass through said passages; and B. temperature responsive magnetic means provided on said tube for compensating for mislanding of said electron beams on incorrect ones of said areas of said screen due to thermal expansion of said beam selecting element resulting in displacement of at least some of said passages relative to their respective areas of said screen, said temperature responsive magnetic means comprising: 1. a permanent magnet, and 2. a magnetic shunt element having temperature responsive variable permeability, said magnetic shunt element forming a path for at least a part of the magnetic flux originating in said permanent magnet and being located on said tube to be heated by heat from said beam selecting element to change the intensity of magnetic flux from said magnetic means with temperature variations in said tube to cause the path of said electron beams landing on the screen to change in response to said thermal expansion of the beam selecting element thereby to maintain excellent color purity of light emitted by said screen, said magnetic element being formed into a block-like shape having a recess on one surface, and said permanent magnet being placed in said recess.