| 摘要 |
<p>PROBLEM TO BE SOLVED: To set a threshold level in following to a level even when the input level is fluctuated due to an environmental change or the like in the case of discriminating the input level. SOLUTION: A light is emitted from a light projection section 2 for each prescribed period and its reflected light is received by a light receiving section 3. The light receiving signal is A/D converted and discriminated by a discrimination means 13. In this case, the discrimination result and input level are stored in a data storage means 14. When a prescribed number of data is stored, a threshold level calculation means 15 discriminates each distribution of the discrimination result and calculates the threshold level to be an intermediate distribution level. Then a display section 6 displays the input level and a current threshold level and displays the calculated threshold level as a recommended threshold level.</p> |
