| 摘要 |
PURPOSE:To obtain an inexpensive fault detector of simple constitution by arranging comb-shaped electrodes in a lattice shape, opposite to each other, on both surfaces of a semiconductor layer covering the overall width of sheet-like body to be checked as photodetection parts. CONSTITUTION:A projection part 2, such as a fluorescent lamp, as long as the size of width perpendicular to the movement direction P of a sheet-like body 1 to be checked, and a photodetection part 3 are arranged with the sheet-like body between. The photodetection part 3 is formed by forming a photoelectromotive force type or photoconductor type semiconductor layer 31 on an insulator substrate 30 and by forming counter comb-shaped electrodes 32 and 33 on both its surfaces in a lattice shape. Part of a light beam Q from a light source 2 reaches the photodetection part 3 through faulty parts 11-13 of the sheet-like body 1, and its output is inputted from terminals 34 and 35 to a discriminating circuit through an amplifier to detect a fault. Consequently, an inexpensive fault detector of simple constitution is obtained. |
