| 摘要 |
<p>A displacement sensor comprises a transducer arrangement (2-11) having sensing regions for sensing energy received from consecutive regions of an object, and moving means (16) for causing an image of the object to move cyclically with respect to the sensing regions. The sensing regions (4-11) are divided into first and second groups, adjacent sensing regions belonging to different groups. The outputs of the sensing regions in the first and second groups are summed to form first and second sums, respectively. The first and second sums are subtracted to form a difference signal. The phase of the difference signal is compared with the phase of the movement produced by the moving means (16) to provide a measurement of displacement. <IMAGE></p> |
