| 摘要 |
<p>A web position control system, e.g. for controlling the position of a moving tape (16) past an optical or magnetic recording head (30) has a pair of outer bearings (32, 34) which constrain the web to follow a linear path which passes symmetrically through gaps between two pairs of air bearings (36, 38). Thus variations in tension do not cause lateral displacement. An air bearing may have a guide surface whose distance from the tape increases in the width direction of the tape, so that there is a wedge-shaped gap (28) with a pressure differential. This may urge the tape so that an edge (26) abuts a guide flange (24).</p> |
