| 摘要 |
<p>A plurality of marks are carried on a movable member, the position of which represents a measured quantity. An image of a mark is projected onto a surface having a large number of detectors. The output signals of the detectors are fed into an evaluation circuit, which sequentially determines the intensity distribution on the detector and, thereby, the position of the mark by means of comparison of fixed threshold values with each of the detector signals and determines the centroid of the thus obtained intensity value distribution. The position of the centroid is a measure of the quantity to be measures.</p> |
