| 摘要 |
PROBLEM TO BE SOLVED: To obtain a BD signal when switching light amount.SOLUTION: When changing first light amount to second light amount smaller than the first light amount, light amount changing means changes the first light amount to third light amount which is smaller than the first light amount and larger than the second light amount before changing to the second light amount. The third light amount is light amount capable of outputting a signal while a first threshold is set.SELECTED DRAWING: Figure 4 |
