| 摘要 |
2066613 9106018 PCTABS00005 An obstruction detection apparatus for use on a movable door, for example, comprises an array of transmitter/receiver pairs (4), each pair comprising a transmitter and receiver in proximity and sharing substantially a common field of view, respective pairs being mounted in spaced apart relationship (d) along the leading edge of a door; a reflection means (6) mounted, adjacent the surface upon which the door closes to lie, within at least part of the field of view (R) of each transmitter/receiver pair, the reflection means having a substantially higher reflection coefficient than any other surface which normally lies within said field of view; and means (20) for detecting a reduction in the signal received by one or more receivers to indicate the presence of an object (7) interposing the door and the reflection means. Furthermore, if the reflection means (6) lies within only a part of the field of view then an increase in the signal received can indicate the entry of an object in the part of the field of view other than that in which the reflection means lies. Thus, two zones can be independently monitored.
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