| abstract |
(57) [Problem] To provide an optical liquid detection function on a transparent substrate without using a prism. SOLUTION: Diffraction gratings 2 and 3 are formed on the indoor side surface of a glass 1, and a light emitting element 4 is arranged near the diffraction grating 2 and a light receiving element 5 is arranged near the diffraction grating 3. When water was attached to the total reflection point on the surface of the glass 1, the light emitted to the diffraction grating 3 was reduced, and when water droplets were attached to the entire total reflection point, the output light was reduced to about 1/50. That is, it was confirmed that the presence of water on the glass surface was sensitively sensed and reflected as the intensity of the emitted light. |