| 摘要 |
<p>The light gate (1) has pairs of transmitters (3,7) and receivers (5,9) emitting light beams (6) forming a given number of beam axes. When there is not obstruction to be beam the beams from the transmitters hit the respective emitters. A transmitter control unit periodically, individually and consecutively activates the transmitters within given sample cycles. A control unit analyses the reception signals at the outputs of the receivers. Within one sample cycle, interruptions of the beam axes due to the presence of an object (11). In the control unit a predetermined plural number of cycles are analyzed for the appearance of beam interruptions to generate an object detection signal.</p> |
