| 摘要 |
PURPOSE:To prevent abrasion, by providing an irradiation position controllable light source adapted to irradiate light selectively to the periphery of a through hole as means of illuminating the periphery of the through hole to eliminate the need for putting a shielding body tight on a printed circuit board. CONSTITUTION:When a printed circuit board 1 on a holding base 2 is conveyed at a fixed speed and a through hole 3 reaches the point (a), an image of the hole 3 is formed on a CCD6 with a lens 5 and a position signal of the hole 3 is obtained with a control circuit 7. After a fixed time, as it reaches the point (b), while beam from a laser unit 8 is deflected with deflectors 9 and 10 to scan the area 11, the position signal obtained at the point (a) is fed to a light shutter 12 to shut down the beam immediately before reaching the hole 3 and an illumination light 4 is blocked from directly entering the opening of the hole 3. Moreover, the image of the hole 3 is formed on the CCD14 through a lens 13 and the CCD14 detects no signal with no defect in the inner wall part of the hole 3 while it does light leaked from a defect, if any. |
