| 摘要 |
<p>The clip or binder for holding sheets of paper or cardboard by their edges makes use of permanent magnets. The magnets (2) are strips with three laid side by side on a much thicker strip of plastic (1). The magnets are so arranged that the north pole of one strip is adjacent to the south pole of the neighbouring strip. Two plastic strips are welded to a piece of plastic sheet (3) which is folded along two parallel lines. In this position the magnetic strips repel each other. When the plastic sheet (3) is folded along a third line lying between the first two folds, opposite poles of the magnets are aligned with each other so that two strips are mutually attracted and clamp the sheet of paper (5).</p> |
