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Method and apparatus for inspecting printed circuit board

  • US 4,758,782 A
  • Filed: 09/10/1986
  • Issued: 07/19/1988
  • Est. Priority Date: 09/11/1985
  • Status: Expired due to Fees
First Claim
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1. An apparatus for inspecting printed circuit boards to detect defective printed circuit patterns formed thereon, comprising:

  • a. image scanning means for scanning a printed circuit pattern of said printed circuit board to produce a pattern image in the form of a plurality of image data;

    b. binary digitizing means for digitizing the image data of said printed circuit pattern to produce a plurality of corresponding binary image data;

    c. first inspection processing means including,extracting means for extracting local binary image data composed of a central bit image and peripheral bit images having a pre-determined bit configuration and being spaced apart from each other, from the binary image data generated by said binary digitizing means, anddetection means composed of a memory device for receiving said extracted local binary image data as an address input and outputting stored data indicating whether a defect exists or not in a pattern area from which said local binary image data is extracted;

    d. second inspection processing means including,converting means for converting the binary image data generated by said binary digitizing means into binary image data of lower resolution than that of the binary image data entered into said first detection means,image data storage means for storing resolutionlowered binary image data of a master printed circuit board, which are scanned, digitized and converted in terms of the resolution by said scanning means, digitizing means and converting means,enlarging and reducing means for enlarging and reducing the resolution-lowered binary image data of the master printed circuit board read out from said image data storage means, anddetection means for detecting defects of the printed circuit board to be inspected, by comparing the image data of the printed circuit board whose resolution is lowered by said converting means, with the enlarged and reduced master image data produced by said enlarged and reducing means; and

    e. output processing means for combining detection results from said first and second detection means to produce output data which can be utilized in a predetermined output device.

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