| 摘要 |
PURPOSE:To know the movement position of a movable optical element by using plural color filters which have different transmissive wavelength ranges and one color sensor, and processing the outputs of the color sensors and obtaining a signal corresponding to a color filter detected by the color sensor. CONSTITUTION:A light source 20 emits energy rays containing light in a 500- 100nm wavelength range, and they are transmitted through, for example, a color filter 12 and incident to the color sensor 14 consisting of two photodiodes 21, 22 having different output characteristics to be converted into an electric signal. The output signal is inputted to a subtracting circuit 25 through logarithmic compressing circuits 23 and 24 to calculate the difference between the output signals of the circuits 23 and 24, thus generating an output signal 26. It has a voltage corresponding to the wavelength of the light incident to the sensor 14, so the signal is inputted to comparators 27-29, which compare the input with a specific voltage set by a voltage divider 30, detecting the movement position of a holder from the relation between the kinds of filters and output signals of the comparators 27-29. |
