| 摘要 |
<p>A proximity detection system for detecting the presence of an object in a given zone or area comprises a transmitter (14) arranged to illuminate that zone (20) and a receiver (16) arranged to receive illumination reflected from that zone (20). The transmitter (14) and detector (16) are arranged such that the presence of an object (24) in the zone (20) results in a decrease in the strength of the signal reflected to the receiver (16). This is because the object (24) casts a shadow (26) in the illumination from the transmitter (14) and the strength of the receiver signal is further reduced by the object (24) preventing transmitted light reflected from a second area (28) from reaching the receiver (16). In one embodiment polarising means are provided to polarise the received and transmitted illumination in substantially orthogonal planes.</p> |
