The number of infrared emission and reception channels of the safety light curtain can theoretically be infinitely numerous. Considering the height of the actual light curtain and the spacing between the upper and lower paths, it generally does not exceed 48.
The safety light curtain is divided into a linear scanning mode and a cross scanning mode. In the linear scanning mode, the single chip transmits the same path selection signal to the transmitting end and the receiving end each time, that is, the first way sends the first way and the second way sends the second way. Roads, ... the fifteenth road to the fifteenth road, the sixteenth road to the sixteenth road. In the cross-scan mode, the microcontroller sends different path selection signals to the transmitter and receiver each time. That is, the first road sends the second road, the second road sends the first road, ... the fifteenth road sends the 16th road, the 16th road sends the fifteenth road. In contrast, the cross-scan mode measures the height of the object more accurately and has the highest detection accuracy at 1/3 of the center of the detection area. The minimum detection height can be reduced to 2/3 in linear scan mode. However, considering the actual needs, it is now common to use a safety light curtain in a linear scanning mode.
One side of the light curtain is equidistantly mounted with a plurality of infrared transmitting tubes, and the other side has the same number of infrared receiving tubes arranged in the same order, each of which has a corresponding infrared receiving tube and is mounted on the same straight line. . When there is no obstacle between the infrared transmitting tube and the infrared receiving tube on the same straight line, the modulated signal (optical signal) emitted by the infrared transmitting tube can smoothly reach the infrared receiving tube. After the infrared receiving tube receives the modulated signal, the corresponding internal circuit outputs a low level, and in the case of an obstacle, the modulated signal (optical signal) emitted by the infrared transmitting tube cannot smoothly reach the infrared receiving tube, and the infrared receiving The tube does not receive the modulated signal, and the corresponding internal circuit output is high. When no object passes through the light curtain, all the modulation signals (optical signals) from the infrared transmitting tube can smoothly reach the corresponding infrared receiving tubes on the other side, so that the internal circuits all output low level. In this way, information on the presence or absence of an object can be detected by analyzing the state of the internal circuit.