| 摘要 |
A photoelectric sensor (2), and in particular, a photoelectric sensor (2) which can eliminate close range detection blind areas without shortening the detection distance, is described. The photoelectric sensor (2) includes a current-limiting resistor (R1) and a photoelectric diode (PD) connected in series for converting an optical signal to an electric signal for use. Two ends of the current-limiting resistor (R1) are connected in parallel with at least one shunt branch (201, 202, 203). The shunt branch (201, 202, 203) includes a shunt resistor (R2, R3, R4) and a switch circuit (2011, 2021, 2031) connected in series. The switch circuit (2011, 2021, 2031) is switched on when the voltage across two ends of the current-limiting resistor (R1) is greater than a predetermined voltage value depending on the shunt branch (201, 202, 203) and is switched off when the voltage across two ends of the current-limiting resistor (R1) is less than the predetermined voltage value. |
