| 摘要 |
<p>The document file has a ring type binder. Several rings are spaced along its length, each being fixed. The sheets of paper (3) for filing are perforated along one side, the spacings corresponding to the rings. Each perforation is keyhole shaped, having a circular hole (4) larger in diameter than the wire (D) of the ring (2). An open slot (5) connects this hole to the outer edge, its width (d) being less than the ring wire (D). The paper is retained by pushing the slots against the rings, these allowing passage over te rings. An infra-red setting coating (3'') can be used to strengthen the perforations.</p> |
