| 摘要 |
The barrier is made up of several plates (3,7), each plate within a first stack including an emitter with a light source (4) and a reflector (5). Within a second stack each plate (7) includes a support and a reflector (9) with a sensor element (8). The plates of the two stacks are aligned so that the light emitted from the sources in the first stack is received by the reflectors in the second stack. The sensors are connected to an electronic detection circuit, sensing when the light incident on the detector is interrupted. The reflectors used by both the emitters and detectors of light are preferably curved, and may be elliptical, and are mounted at the end of cone shaped light guides.
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