| 摘要 |
PURPOSE:To simplify the constitution of a color component ratio detecting device, by providing the constitution, wherein the charging voltage of one capacitor becomes a two color component ratio when the other capacitor, which is charged in proportion to the illuminance of each color component, is charged to a specified voltage. CONSTITUTION:The component of blue light, which is transmitted through a filter 42, is received by a light conductive element cds1 of a light receiving circuit 32, and a photoelectric current flows. Then a transistor Q5 is turned OFF through a comparator CP2, and a transistor Q6 for a similar red light receiving circuit 34 is turned OFF. A capacitor C1 is charged through current mirror circuits Q1 and Q2, and a capacitor C2 is likewise charged. When the charging voltage of the capacitor C1 reaches a specified value, an FET is turned OFF by a comparator and CP1, and the charging of the capacitor C2 is stopped. The charging voltage VBR of the capacitor C2 becomes each color component ratio. The simple constitution, which does not require circuits for logarithmic compression and expansion, subtraction, and the like, is obtained. |
