| 摘要 |
PURPOSE:To improve the distance measurement accuracy and to prevent a signal value from exceeding a dynamic range by stopping at least a 1st or 2nd integrating means from operating according to a 1st or 2nd comparing means. CONSTITUTION:The device is equipped with the 1st integrating means 30 which performs integrating operation corresponding to a 1st current value I1, the 2nd integrating means 31 which performs integrating operation corresponding to a 2nd current value I2, the 1st comparing means 35 and 2nd comparing means 36 which compare the output of the 1st integrating means 30 and the output of the 2nd integrating means 31 with reference voltage respectively, and an arithmetic means 34 which calculates a subject distance according to the ratio of the 1st current value I1 and 2nd current value I2. At least the 1st integrating means 30 or 2nd integrating means 31 is stopped from operating according to the 1st comparing means 35 or 2nd comparing means 36. Namely, random noises that a signal photocurrent for AF contains are canceled by performing integration plural times. |
