| 摘要 |
PROBLEM TO BE SOLVED: To provide a multi-optical-axis photoelectric sensor capable of carrying out stable detection without being influenced by noise even if a signal line for transmitting light receiving signals becomes long due to an increase in the number of optical axes. SOLUTION: The output of each light receiving circuit 22 is provided with an output buffer circuit 23 comprising a transistor Tr and an output resistance R1, which functions to lower the output impedance of the light receiving circuit 22. Both ends of the output resistance R1 are connected to a signal line L1 and a signal line L2 respectively through switching elements S1, S2. The respective control terminals of the switching elements S1, S2 are connected in common to a signal terminal of a shift register 24 driven in response to a driving signal from a CPU 25. The switching elements S1, S2 are normally in the OFF state, and when receiving a driving signal from the CPU 25 through the shift register 24, both switching elements S1, S2 are simultaneously operated ON synchronously with the driving timing of a light projecting element 11. Both signal lines L1, L2 are laid from the upper end side toward the lower end side of the multi- optical-axis photoelectric sensor according to a circuit pattern formed on a PC board and set to have the same shape. |
