| 摘要 |
A problem with a stability time is solved, and a variation in gain and a variation in output offset voltage decrease to improve detection accuracy of a photodetector-side circuit used in a light curtain (31). Plural-stage filter portions (37a, 37b) are connected to an I/V conversion circuit (36) that converts a photocurrent passed through a light receiving element (35) in receiving light. Each of the filter portions (37a, 37b) includes a high-pass filter (53) and an amplifying circuit (54), and a cutoff frequency of the high-pass filter (53) can be switched by a filter switching signal (FS). |
