| 摘要 |
<p>Light barrier apparatus generally features a light transmitter for projecting light across a region to be monitored to a light receiver. The light transmitter and receiver units can either be separate or can be combined in a single housing and used in conjunction with a retro-reflector for returning light from the sender to the receiver.</p><p>In any of these arrangements the light transmitter and/ or sender units incorporate photoelectric converter components (11, 12) and optical projection components (13, 14) together with electronic processing elements which enable interruption of the light barrier to be detected. The present arrangement features a housing (17) including at least one sealed chamber (15; 15', 15") containing solely the optical and photoelectric converter elements. These chambres are thus sealed against the ingress of contamination and moisture. The remaining elements of the electronic processing circuit are housed separately in a further chamber (16). The housing together with the fixed walls (18, 18', 18") of the sealed chambers (15, 15', 15") is usefully injection molded in one piece and preferably together with sighting aids (22).</p> |
