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Automatic circuit board tester

  • US 4,240,750 A
  • Filed: 10/02/1978
  • Issued: 12/23/1980
  • Est. Priority Date: 10/02/1978
  • Status: Expired due to Term
First Claim
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1. An electrical circuit board testing system comprising:

  • a circuit board having a plurality of connective holes therethrough and electrically conductive leads of components extending along said board in discrete and varied directions to said holes;

    positioning means for holding and positioning a said printed circuit board under test at a precise position, wherein a face of said board to be examined is unobscured;

    a counter;

    illumination means, including a laser and focusing optics, for focusing a beam of laser light onto the face of said printed circuit board held by said positioning means;

    scanning means responsive to a discrete count from said counter for positioning said beam along selected paths which include paths substantially normal to and across radial lines from said holes and accordingly substantially normal to said leads on said board;

    detection means spaced from said printed circuit board and spaced from and to the side of said beam for sensing the amplitude of scattered laser light from separate discrete regions of said board as said board is scanned and for providing discrete electrical outputs, each representative of the amplitude of scattered light from a discrete region of said board as it is scanned; and

    reference means including an electrical memory having discrete electrical values, representative of discrete amplitude values of scattered light from a reference circuit board resulting from exposure of said reference circuit board along like said selected paths, said values being stored in said memory and located by discrete counter addresses, and said reference means including means for reading out said discrete electrical values responsive to said counter;

    whereby selected paths, or a selected series of paths, of scanning may be effected in any direction and at any location on said board, and the existence and location of a conductor on the surface of said board detected and compared with the existence or location of a conductor on said reference board which lies substantially normal to a said path.

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