| 摘要 |
<p>PROBLEM TO BE SOLVED: To output information on the possibility that detecting operation cannot be processed within the dynamic range of a photodetecting circuit in advance by providing a decision means which judges that there is a saturated area when the quantity of reflected light exceeds its dynamic range. SOLUTION: This device consists of a light projecting element 11 which projects near infrared rays as a projection beam, an optical system 13 for projection which divides the near infrared rays from the projection element 11 into areas 15a to 15c, a photodetecting element 12 which photodetects reflected lights from the respective areas through an optical system 14 for photodetection, and a microcomputer 16. The microcomputer 16 decides saturation with information from the photodetecting element 12 and outputs it. Namely, the CPU of the microcomputer 16 compares the peak value of an analog signal indicating the quantity of reflected light photodetected by the photodetecting element 12 with the maximum value of the analog signal of the photodetecting element 12 and judges that there is a saturated area when the peak value is larger than the maximum value.</p> |
