| 摘要 |
PURPOSE:To detect the defective part of a transparent or semi-transparent plate-shaped body to be inspected by scanning linearly a line array disposed with plural lines at equal intervals through the plate-shaped body in the direction orthogonal with said array, photographing the array and detecting the part where the regularity of an electric signal is disturbed. CONSTITUTION:The regular electric signal of a specified period corresponding to the intervals of the line array 3 is obtd. when the transparent or semi-transparent plate-shaped body is carried within the linear image pickup field of a one-dimensional image pickup device 1 by a moving device 5. The refracting way of light at the defective part 8a, if existing in the body 8, is different from the refracting way of the light in the other part and therefore the electric signal of the disturbed irregularity appears. The electric signal is first passed through a band-pass filter 10 and is converted to the voltage proportional to the envelope by an envelope circuit 11. The voltage is further compared by a comparator circuit 12 of whether the voltage is higher or lower than the threshold value TH. The voltage is inverted by an inversion circuit 13 and is used as a detection signal. |
