| 摘要 |
<p>The reading head for magnetic identification cards has two restricted degrees of freedom of movement to allow a single head (36) to read, with minimal displacement, warped and bent cards. The head has partial movement along the card track, and also possesses two partial degrees of rotational freedom. The surface of the cylindrically shaped head (36) is lightly convex (37) and has the magnetic inserts flush with the convex surface. Two diametrically opposite grooves (40,41) run along the length of the outer wall of the cylinder and have spring loaded (49,50) balls (47,48) running inside them to support the head. The magnetic card passing over the convex surface exerts a force which tends to tilt or twist the cylindrical head until it lies as closely as possible to the card surface.</p> |
