| 摘要 |
PROBLEM TO BE SOLVED: To provide a uniform convergence-correcting magnetic field by providing coil supports integrally molded from plastics on the inner periphery of a magnetic substance which is formed into a ring from a ferrite. SOLUTION: A plurality of coil columns 16 are provided at 45-degree intervals on the inner peripheral wall of a cylinder 15 made from plastics, and flanges 17 are provided at their ends by integral molding. Coils 18a∼h are wound on the coil columns 16, and the cylinder 15 is inserted inside the inner periphery of a magnetic substance 14 formed into a ring from a ferrite, to constitute a convergence correcting part. The coils 18a∼h are connected together in such a way that those 90 degrees apart from each other are connected together. For example, the coils 18a ,c ,e ,g are connected in series with the coils 18b ,d ,f ,h respectively. Also, the coils are connected while their directions of winding are inverted alternately. Since the shape of the magnetic substance 14 is simple, dimensional accuracy can be obtained readily. Since the cylinder 15 and the coil columns 16 are accurately shaped by molding dies, the convergence correcting part is shaped with precision.
|
