| 摘要 |
PURPOSE:To increase the quantity of incident light on a light receiving element to improve S/N by arranging pairs of light emitting element and light receiving element independent of each other in an optical negative feedback circuit. CONSTITUTION:The audio signal inputted to an analog signal direct light intensity modulating circuit 1 is amplified by an amplifying circuit 1a and is inputted to a light emission diode 1b. The obtained optical signal is inputted to a photo diode 3b through an optical fiber 2, and the signal converted to an electric signal is outputted as an audio signal through an amplifying circuit 3a. On the other hand, the output signal is amplified by an amplifying circuit 4a and is inputted to a light emission diode 4b. The obtained optical signal is inputted to a photo diode 6b through an optical fiber 5, and the signal converted to an electric signal is level adjusted by an amplifying circuit 6a and is inputted to the analog signal direct light intensity modulating circuit 1. Thus, light emitting element and light receiving element for optical negative feedback correspond to each other independently and the sufficient quantity of incident light on light receiving element is obtained. |
