| 摘要 |
PURPOSE:To improve the SN ratio and the measurement accuracy by variably controlling the exposure time of a CCD line camera to increase the value of a video signal output by making the time long. CONSTITUTION:This system consists of a lamp 2 for illumination, the CCD line camera 3, a camera driving part, an image signal processing part, and a VTR 4. Then the camera 3 picks up images of a run road surface irradiated by the lamp in lines according to the run of a vehicle. At this time, the camera driving part inputs a horizontal synchronizing signal from the VTR 4 to a frequency dividing circuit 303 and a shift clock for opening/closing control over shift gates 33 and 34 is outputted. Then, the frequency division ratio of the circuit 303 is varied and set through external operation and an exposure time corresponding to the period of the shift clock is set in the camera 3. Assuming that the frequency division ratio of the circuit 303 is 1/2, the exposure time of the camera 3 is double and the video output signal is also double, so that the SN ratio is improved.
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