| 摘要 |
<p>A magnetic disc stack recording system includes a facility for protection by detection of the height of the stack. Typically, a full stack of discs (3) consists of ten individual discs mounted on a central support (1). A top cover (7) is located over the stack and has a seal (8) around the edge. A clamping ring (11) ensures that only a small air gap exists connecting the inner region (9) and the disc area. When the discs are rotated, air is expelled from the central region and a small vacuum (1.5 mbar) exists in the inner region. This maintains a switch (10) in the closed condition in order to activate the head. If the stack contains a smaller number of discs, the pressure stays high and the switch opens.</p> |
