| 摘要 |
<p>@ A reflection light barrier for recognising also strongly reflecting articles has at one side of a monitored region a light transmitter (13) which is combined with a light receiver (12) and, at the other end of the monitored region, a reflecting device (11). The reflecting device (11) has optical filter characteristics so that the spectral distribution of the light beam is changed on reflection. An electronic processing circuit only produces a signal following the incidence of reflected light on the receiver when the spectral distribution does not correspond with the spectral distribution of light reflected from the reflecting device.</p> |
