ROAD SURFACE DISCRIMINATION DEVICE

PURPOSE:To discriminate road surface without wrong operation, by a method wherein a light receiving device detects visible regular reflection ray, irregular reflection ray and infrared irregular reflection ray from a road surface which is irradiated, the detected output is compared with a setting value, and the setting value is corrected. CONSTITUTION:Reflection ray from a road surface which is irradiated from a projector 24 is detected by an infrared ray receiving element 31 and a visible ray receiving element 32 in an irregular reflection ray receiving device and by a visible ray receiving element 33 in a regular reflection ray receiving device. The detected output is passed through an amplifier 34, a band-pass filter 35 and an amplifier 36 and entered into comparators 41-43 where it is compared with reference level A, B1, B2, C. Signal as compared result is fed through a logic circuit 44 to a processing unit 45. Temperature signal from a thermometer 28 is also fed to the processing unit 45, reference level in the comparators 41-43 is adjusted corresponding to variation of light projection amount, and the road surface state discrimination signal is outputted. This enables the road surface discrimination without wrong operation.