| 摘要 |
PURPOSE:To detect the defect of a through-hole in a printed board by one photodetecting means by providing a photomask, etc., in front of one sensor element assembly. CONSTITUTION:When the printed board 3 is at a position 3, light 5 projected from the lower part of the through-hole 6 passes the center hole of the hole 6 and is incident on through-hole arrays 13a-13d bored in the mask 12 of the photodetecting means 15. Then, the output of the sensor element assembly is supplied to a demarcation circuit 15 to detect the position of the hole 6. When the printed board moves to a position 3a, a light shield mask 4 is provided on the reverse surface of the position-detected hole 6 and light 5 is projected. If there is a defect, leaking light is emitted from the center hole of the hole 6 through a lens 18 and incident on the through-hole arrays 14a-14e bored in the mask 12 of the means 15; and the output of the assembly 10 is supplied to the circuit 16 to detect the pinhole defect while no leaking light is obtained when the printed board is normal. |
