| 摘要 |
PURPOSE:To improve a detecting accuracy by comparing first and second extract signals extracted from first and second space filters, respectively, with each other and calculating the speed of an object to be detected on the basis of the result of comparison. CONSTITUTION:Reflected light from a road 11 is supplied to a spatial filter 13 via a lens 12 and composite voltages proportional to the quantity of the reflected light are generated in first, second, third and fourth detecting element groups A2(n-1), A2n, B2(n-1) and B2n, respectively. Then, the output signals of the element groups [A2(n-1) and A2n] and [B2(n-1) and B2n] are inputted to first and second differential amplifiers 15A and 15B, respectively. Then, first and second extract signals phiA and phiB wherein low noises are removed from signals with a spatial frequency (f) which are detected by the element groups [A2(n-1) and A2n] and [B2(n-1) and B2n] are outputted from the amplifiers 15A and 15B, respectively. The signals phiA and phiB are inputted to comparing means E and a deviation between the signals phiA and phiB is outputted as the signal tau of time. The moving speed V of an object to be detected is calculated F from the signal tau and displayed 21.
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