| 摘要 |
PURPOSE:To reduce an electric current based on background light and detect infrared light with high accuracy by FET-biasing an output current of diodes for detecting the infrared light with a capacitor and a reset switch and also integrating through an integration circuit after separation of the output current. CONSTITUTION:In addition to resetting a switch 3-1 as well as an electric charge of a capacitor 2-1, a reset switch 3 is resetted. Such an operation permits the capacitor 4 (bias) to be at a constant voltage and a gate voltage of a field-effect transistor (FET) 5 to be at a prescribed rate. After that, the reset switch is so kept to be OFF that a cource and gate voltage of the FET 5 is kept constant and its FET 5 operates as a constant current source. Accordingly, integral calculus is carried out by decreasing an electric current corresponding to background light with the FET. Thus, such an operation detects an effective current component and can improve measurement accuracy of an infrared ray detection element. |
