| 摘要 |
PURPOSE:To execute communication with optimum light quantity, which is optimum for light communication, without being affected by a light emitting element, a light detecting element or an optical fiber by providing a light quantity control means to switch the light emission quantity of the light emitting element. CONSTITUTION:A photo-transistor 7, which is the light detecting element, is connected through an external device and an optical fiber 8. Then, the photoelectric conversion of optical serial data from the optical fiber 8 is executed and the data are sent to a binarizing circuit 9. A photo-detection quantity detecting circuit 6, which monitors a voltage level to be outputted by a photo-transistor 7 and a resistor R1, executes the analog/digital conversion of an inputted voltage VD and outputs a converted result as a detected voltage value PD to a controller 1. A current control circuit 2 controls the driving current of an LED3, which is the light emitting element, by a current control value LD which is inputted from the controller 1. Thus, the light communication can be surely executed without being affected by the lowering of the light quantity, which is generated together with the degradation of the light emitting element, or the difference of a transmitting characteristic of the optical fiber. |
