| 摘要 |
PROBLEM TO BE SOLVED: To improve range-finding accuracy by judging that the reflectance of a range-finding object is low and a distance to the range-finding object is long in such a case and making the level of a clamp signal low so that range- finding may be performed. SOLUTION: The clamp signal is set to IC1 and the integrate number of an output ratio signal in an integration circuit 15 is set to N1, then a 1st range- finding value D1 is detected (S3). When the value D1 is larger than a reference distance L1, the clamp signal is set to IC2 smaller than IC1 and the integrate number is set to N2, then a 2nd range-finding value D2 is detected (S4 and S5). When a difference obtained by subtracting the value D1 from the value D2 is larger than a specified value DD, the clamp signal is set to IC2 and the integrate number is set to N3, then a 3rd range-finding value D3 is detected (S6 and S7). A distance to the range-finding object is obtained by weighted- averaging the values D2 and D3 in accordance with the integrate numbers N2 and N3 (S8). |
