| 摘要 |
PURPOSE:To prevent the breakdown of a jacket due to the stress concentrated at the area near a contact window of a head, by providing the folding preventing cuts bisymmetrically at the area near the contact window. CONSTITUTION:A square jacket 3 stores a disket 2 having a center hole 1. Then the continuous curved line type cuts 12 of semicircular formes with which the tangent line is unconditionally decided at any point are provided bisymmetrically at the area near a contact window 4 and at an edge part of the jacket 3. Thus the stress scattered 18 when the folding force is applied as shown by an arrow 17. Therefore no folding occurs at a specific area near the window of 4. |
