| 摘要 |
<p>The light barrier (L1) has a controller for controlling a transmitter (S1), and an evaluation unit for evaluating a signal from a receiver (E1). The controller controls the transmitter so that the transmitter outputs signal having strength below a threshold and signal having strength above the threshold signal during specific period of time. The evaluation unit detects the signal received by the receiver as valid only if the signal has pattern with corresponding waveform. An independent claim is included for light grating.</p> |
