| 摘要 |
PURPOSE:To prevent an erroneous data from being outputted at the time of inputting/outputting the rays of light to and from a photoirradiating area, by transmitting a mark just before and immediately after data transmission, and setting a time until the transmission of both marks are completed longer than that of the transmission of a data. CONSTITUTION:An ASK-modulated data is outputted from a shift register 5, and is supplied to an optical modulator, and a modulated optical signal is transmitted to a space. The data consists of four bits, and the transmission time is t1, and a space consists of six bits, and the transmission time is t2, and it is set as t1<t2. The ASK-modulated optical signal is received with a photodetector such as a phototransistor, and is inputted to a reception part. The reception part does not perform immediately the processing of a reception signal inputted to and received at the projecting area 4, and the data is not decided as a normal data until the data folloving a received start bit is received after the lapse of the time t2, and a following stop bit is detected. Therefore, it is possible to prevent the erroneous data from being outputted. |
