| 摘要 |
PURPOSE:To attempt to realize a coil of a low distortion factor without increasing configurations of cores by specifying the ratio of the area of a drum core to that of each part of a cap core movable up and down. CONSTITUTION:A drum core 1 on which a winding 3 is wound is fixed to a terminal plate 4, a cap core 2 is variably supported with mold 5, and variable coils 1 and 2 are shielded with a shielding case 6. In this case, when the diameter of the core tube of the drum core 1, the diameter of a flange, the thickness of the flange, the inner and outer diameters of the cap core 2 and the thickness of a head thereof are represented by A, B, C, D, E and F, the ratios among the following areas S1=pi(A/2)<2>, S2=piXAXC, S3=pi{(E/2)<2>-(D/2)<2>} and S4= piXBXF are made in such a manner that S1/S2=0.8+ or -15%, S1/S3=0.75+ or -15% and S3/S4= 0.7+ or -15% hold. Use of such a coil of a low distortion factor allows a LC filter of a small size and a low distortion factor to be formed. |
