| 摘要 |
PURPOSE:To detect the pattern of a printed-wiring board having wiring patterns on the upper and the lower surfaces thereof, by a method wherein light to be irradiated is obliquely irradiated from a position not irradiating the wiring pattern on the lower surface of said bord and previous light is detected on the upper surface of the board. CONSTITUTION:A board 2 having wiring patterns 1a, 1b formed to the upper and the lower surfaces thereof is obliquely irradiated at an angle theta with light S to be irradiated from a position not irradiating the lower surface pattern 1b. When previous light is detected on the upper surface of the board 2, the upper part of the upper surface pattern 1a is blocked from light and light is not detected at all while light S<1> generated by the irregular reflection of incident light S in the inner layer pattern 1 is detected on the board between with the upper surface pattern 1a. In addition, because the part of the lower surface pattern 1b is detected as a high voltage level as compared with the upper surface pattern 1a, only the upper surface pattern can be detected by setting a binarized level Va. |
