| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a light receiving device which does not need strict calibration and can correctly detect a desired light ray and to provide an optical communication system using it. <P>SOLUTION: A first light receiving element 21 has its peak of photosensitivity to the wavelength of a desired light ray (infra-red ray) and outputs an output signal in response to its light receiving level. A second light receiving element 22 has its peak of photosensitivity to the wavelength which is shorter than that of the desired light ray and is between that of the desired light ray and that of the visible light ray and outputs an output signal in response to its light receiving level. The wavelength of the photosensitivity of the first and second light receiving elements 21 and 22 is characterized in that the same shape is shifted in the direction of the wavelength. A difference detector 3 subtracts the output signal of the second light receiving element 22 from the output signal of the first light receiving element 21 to find the light receiving signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
