Magnetic focusing system with improved symmetry and manufacturability
First Claim
Patent Images
1. A magnetic focusing system for focusing an electron beam, comprising:
- a pair of pole pieces having central holes and outer perimeters;
a plurality of permanent rod magnets having respective north-pole ends and south-pole ends, said north-pole ends being disposed in contact with one of said pole pieces at equally-spaced-points around its outer perimeter, said south-pole ends being disposed in contact with another of said pole pieces at equally spaced points around its outer perimeter, and said permanent rod magnets being separated so as not to make mutual contact with one another;
a hollow bobbin means for supporting at least one coil and having ends disposed in contact with said pole pieces and concentric with said central holes of said pair of pole pieces; and
a dynamic focusing coil wound around said hollow bobbin means.
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Abstract
A magnetic focusing system has a pair of disc-shaped pole pieces between which several permanent rod magnets are mounted, their north poles in contact with one pole piece and their south poles in contact with the other pole piece. The permanent rod magnets are equally spaced around the outer perimeters of the pole pieces, and are separated from one another so that they do not create a ring. The pole pieces have central holes, between the rims of which a symmetric magnetic lens is formed for focusing an electron beam.
53 Citations
32 Claims
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1. A magnetic focusing system for focusing an electron beam, comprising:
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a pair of pole pieces having central holes and outer perimeters; a plurality of permanent rod magnets having respective north-pole ends and south-pole ends, said north-pole ends being disposed in contact with one of said pole pieces at equally-spaced-points around its outer perimeter, said south-pole ends being disposed in contact with another of said pole pieces at equally spaced points around its outer perimeter, and said permanent rod magnets being separated so as not to make mutual contact with one another; a hollow bobbin means for supporting at least one coil and having ends disposed in contact with said pole pieces and concentric with said central holes of said pair of pole pieces; and a dynamic focusing coil wound around said hollow bobbin means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A magnetic focusing system for focusing an electron beam, comprising:
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a pair of pole pieces having central holes and outer perimeters; a plurality of permanent rod magnets having respective north-pole ends and south-pole ends, said north-pole ends being disposed in contact with one of said pole pieces at equally-spaced-points around its outer perimeter, said south-pole ends being disposed in contact with another of said pole pieces at equally spaced points around its outer perimeter, and said permanent rod magnets being separated so as not to make mutual contact with one another; and a correcting coil wound around each of said plurality of permanent rod magnets.
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27. A magnetic focusing system for focusing an electron beam, comprising:
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a pair of pole pieces having central holes and outer perimeters; a plurality of permanent rod magnets having respective north-pole ends and south-pole ends, said north-pole ends being disposed in contact with one of said pole pieces at equally-spaced-points around its outer perimeter, said south-pole ends being disposed in contact with another of said pole pieces at equally spaced points around its outer perimeter, and said permanent rod magnets being separated so as not to make mutual contact with one another; at least one correcting coil to which a direct current is applied for magnetic flux adjustment; a correcting circuit for feeding said direct current to said correcting coil, said correcting circuit including, at least one temperature sensor for sensing surface temperature of one of said permanent rod magnets and producing an output signal, and a driver coupled to feed current to said correcting coil responsive to output of said temperature sensor. - View Dependent Claims (28)
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29. A magnetic focusing system for focusing an electron beam, comprising:
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a pair of pole pieces having central holes and outer perimeters; a plurality of permanent rod magnets having respective north-pole ends and south-pole ends, said north-pole ends being disposed in contact with one of said pole pieces at equally-spaced-points around its outer perimeter, said south-pole ends being disposed in contact with another of said pole pieces at equally spaced points around its outer perimeter, and said permanent rod magnets being separated so as not to make mutual contact with one another; a flanged tube having a tube extending through said central holes in said pole pieces and a flange extending outward from one end of said tube at right angles to said tube; and an alignment board having a central hole through which said tube of said flanged tube is inserted and a plurality of holes through which said permanent rod magnets are inserted. - View Dependent Claims (30)
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31. A magnetic focusing system for focusing an electron beam, comprising:
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a pair of pole pieces having central holes and outer perimeters; a plurality of permanent rod magnets having respective north-pole ends and south-pole ends, said north-pole ends being disposed in contact with one of said pole pieces at equally-spaced-points around its outer perimeter, said south-pole ends being disposed in contact with another of said pole pieces at equally spaced points around its outer perimeter, and said permanent rod magnets being separated so as not to make mutual contact with one another; and a flanged tube having a tube extending through said central holes in said pole pieces and a flange extending outward from a central portion of said tube at right angles to said tube, said flange having a plurality of tubular magnet-holders through which said permanent rod magnets are inserted. - View Dependent Claims (32)
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Specification