| 摘要 |
PURPOSE:To heighten a light transmitting level by obtaining at least one modulated digital signal composed of a pulse train having a pulse width narrower than its bit width for every bit period from an original digital signal composed of a binary digit string to be transmitted, converting the modulated digital signal into a light signal, and transmitting the light signal. CONSTITUTION:The duty ratio of a modulated digital signal TM becomes considerably smaller compared with that of an original digital signal TX, and the duty ratio and the mark ratio of a light signal TO to be transmitted become considerably smaller compared with that when the original digital signal TX is directly converted into the light signal. Consequently, even when the peak value of a current applied to a light emitting element 21 is heightened, the mean value becomes considerably lower compared with that when the original digital signal TX is directly converted into the light signal. Thus, even when the light emitting element 21 is a light emitting diode, etc., having small light emitting ability, the light signal TO having high peak power can be obtained, and the light transmitting level can be heightened. |
