| 摘要 |
PURPOSE:To detect accurately the dry state, the wet state, th snowy state, the frozen state, etc. of the road surface even if vehicles come, by projecting visible rays and infrared rays to the road surface and discriminating respective photodetection levels of the regular reflection light and diffused reflection light of visible rays and the diffused reflection light of infrared rays. CONSTITUTION:Visible rays and infrared rays are projected to a road 21 from a mercury-arc lamp 24, and reflection lights are received by a regular reflection light receiver 26 and a diffused reflection light receiver 25. The temperture of the road surface is measured by a radiation thermometer 28, and the quantity of projection light of the mercury-arc lamp 24 is measured by a projection light quantity level measurer 27. In respect to reflection lights, the regular reflection light of only visible rays is received, and diffused relfection lights of visible rays and infrared rays are received individually. The state of the road surface is discriminated by the overall judgement of these quantities of received light and the temperature of the road surface. In case that a vehicle comes, three factors, namely, rapid reduction of the regular reflection light of visible rays, rapid increment of the diffused reflection light of visible rays, and lowering of the output of the thermometer for the road surface are discriminated. |
