Focus magnet with separate static and dynamic control coils
AssigneeHitachi Metals, Ltd.
InventorsTeruo Umehara, Fumihiko Takahashi
Life of this patent
Estimating the term…
Abstract
A focus magnet having (a) three axially magnetized hollow cylindrical permanent magnets disposed concentrically along a center axis of a cathode ray tube such that their opposite magnetic poles face each other; (b) yokes in the form of hollow discs disposed on both sides of the permanent magnets; (c) a static control coil disposed inside a center permanent magnet; (d) a horizontal dynamic control coil disposed inside one of side permanent magnets; and (e) a vertical dynamic control coil disposed inside the other side permanent magnet, whereby electron beams passing in the cathode ray tube are converged to a small spot diameter.
Claims4
A focus magnet comprising (a) three axially magnetized hollow cylindrical permanent magnets disposed concentrically along a center axis of a cathode ray tube such that their opposite magnetic poles face each other;
- (b) yokes in the form of hollow discs disposed on both end surfaces of permanent magnet;
- (c) a static control coil disposed inside a center permanent magnet;
- (d) a horizontal dynamic control coil disposed inside one of side permanent magnets;
- and (e) a vertical dynamic control coil disposed inside the other side permanent magnet, whereby electron beams passing in said cathode ray tube are converged to a small spot diameter.
Dependencies are inferred from the claim text.