| 摘要 |
PROBLEM TO BE SOLVED: To prevent mutual interference with other machines by properly adjusting light-project quantity. SOLUTION: Each determination timing and each threshold are set previously so that at normal incoming of light, the timing, when a light-receiving signal level is at peak is made the first determination timing, the timing when the light-receiving signal level becomes higher than the first threshold and decreases from the peak is made the second determination timing, and the light-receiving signal level at that time is below the second threshold. As a result, at excess incoming light, since when the light-receiving signal level decreases is delayed, it can be determined to be in excess light incoming state, since the level is higher than the second threshold at the second determination timing; and at insufficient light quantity, it can be determined as being insufficient of light, since the light-receiving signal level is lower than the first threshold at the first determination timing. Accordingly, by changing the projected light quantity of a light-projecting element, the light-receiving signal level lies in this range, the projected light quantity can be adjusted properly, and mutual interferences with other machines can be prevented. COPYRIGHT: (C)2008,JPO&INPIT
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