| 摘要 |
PURPOSE:To prevent evil influence from being exerted upon a magnetic sheet even if a hub made of plastics deforms according to temperature and humidity condition by using metallic material for a receiving surface where the sheet inner circumferential edge part of one of hub structures having the hub is clamped. CONSTITUTION:The magnetic sheet 6 and the plastics-made hub 7 consisting of the upper and lower hub structures 7a and 7b are provided, and the inner circumferential edge part 6a is clamped between the joint surfaces of both hub structures 7a and 7b. Then, the receiving surface for clamping the sheet inner circumferential edge part 6a of at least one of the upper and lower hub structures 7a and 7b is made of the metallic material 13. |
