| 摘要 |
PURPOSE:To employ an EL element as optical sensor by utilizing the fact that the electrostatic capacity of an EL element varies with the intensity of illumination of incident light when no light is emitted therefrom. CONSTITUTION:A c-f converter 8 employs an EL element as optical sensor for the electrostatic capacity C of CR type oscillator, for example, as illustrated to convert the electrostatic capacity to an oscillation frequency. The oscillation frequency is converted to a voltage with a f-v converter 9, which is inputted into a comparator 10 set for desired threshold. The comparator 10 performs a switching by operating a switching circuit 11. |
