US5506793A
Expired / Lapsed
US
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Method and apparatus for distortion compensation in an automatic optical inspection system
Assignee: Gerber Systems Corp
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Filing: 1994-01-14
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Granted: 1996-04-09
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Expires: 2014-01-14
Abstract
Abstract A method and apparatus for compensating substrate distortion in automatic optical inspection (AOI) systems eliminates false error signals during printed circuit boards (PCB) defect detection. The present invention is used in feature edge transition AOI systems that employ pixel to pixel comparison between CAD and scanned PCB feature databases. The present invention divides the substrate into a plurality of regions or "tiles". A distortion vector for each tile is calculated and is used to generate a shift of pixels within each tile which removes any variation between the preferred pixel location and the actual pixel location, thereby enabling the AOI system to avoid generating error signals when features are only misplaced on the substrate.
Inventors
- 👤 Ronald J. Straayer
- 👤 Scott P. Snietka
- 👤 Peter M. Walsh
- 👤 James P. Kohler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 23:49
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/28; G01R31/2801; G01R31/2805; G06; G06T; G06T7/00; G06T7/30; G06T7/32; G06T7/70; G06T2207/00; G06T2207/30; G06T2207/30108; G06T2207/30141
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
168 words
A method of substrate distortion compensation for use in an automatic optical inspection (AOI) system, said method comprising the steps of: receiving pixel signals indicative of a database of features of preferred dimension and location to be fabricated on said substrate, said preferred dimension database signals including signals corresponding to pixels spaced across said substrate in a sequence of scan lines, with said features demarked by pixel state transitions; grouping said preferred dimension database signals into a plurality of signal arrays corresponding to tile regions of said substrate; receiving pixel signals indicative of a database of features scanned from said substrate; grouping said scanned database signals into a plurality of signal arrays corresponding to tile regions of said substrate; comparing a preferred tile region signal array with a corresponding scanned tile region; generating distortion vector signals indicative of a variation in scanned pixel location from said preferred pixel location; and generating signals for presentation to said AOI system for removing said pixel location variation during substrate defect detection.
Claim 2
Independent Claim
168 words
A method of substrate distortion compensation for use in an automatic optical inspection (AOI) system, said method comprising the steps of: receiving pixel signals indicative of a database of features of preferred dimension and location to be fabricated on said substrate, said preferred dimension database signals including signals corresponding to pixels spaced across said substrate in a sequence of scan lines, with said features demarked by pixel state transitions; grouping said preferred dimension database signals into a plurality of signal arrays corresponding to tile regions of said substrate; receiving pixel signals indicative of a database of features scanned from said substrate; grouping said scanned database signals into a plurality of signal arrays corresponding to tile regions of said substrate; comparing a preferred tile region signal array with a corresponding scanned tile region; generating distortion vector signals indicative of a variation in scanned pixel location from said preferred pixel location; and generating signals for presentation to said AOI system for removing said pixel location variation during substrate defect detection.
Claim 3
Dependent Claim
39 words
The method of claim 1 wherein said preferred dimension database signal grouping step further comprises the steps of grouping said preferred dimension tile region signals into arrays having dimensions, in pixels, greater than said scanned tile region signal arrays.
Claim 4
Dependent Claim
86 words
The method of claim 1 wherein said scanned and preferred tile regions each comprise a center pixel and said method further comprises the steps of: centering said scanned and preferred tile region signal arrays about said center pixels; adjusting said preferred tile region pixel signal array position relative to said scanned pixel signal array by at least one pixel; and determining if said adjusted preferred tile region pixel array position yields a lesser magnitude of said variation than said centered preferred tile region pixel array position.
Claim 5
Dependent Claim
30 words
The method of claim 3 further comprising the steps of computing histogram signals indicative of a total value of feature enabled pixels across a one of said tile region dimensions.
Claim 6
Dependent Claim
22 words
The method of claim 4 further comprising the steps of generating said histogram signals for each orthogonal direction of said tile regions.
Claim 7
Dependent Claim
39 words
The method of claim 5 further comprising the steps of selecting an adjusted tile region pixel array position in dependence on which of said adjusted tile region pixel array positions yields maximum correlation in said computed histogram total values.
Claim 8
Dependent Claim
185 words
A substrate distortion compensation apparatus for use in an automatic optical inspection (AOI) system, said apparatus comprising: a means for receiving pixel signals indicative of a database of features of preferred dimension and location to be fabricated on said substrate, said preferred dimension database signals including signals corresponding to pixels spaced across said substrate in a sequence of scan lines, with said features demarked by pixel state transitions; a means for grouping said preferred dimension database signals into a plurality of signal arrays corresponding to tile regions of said substrate; a means for receiving pixel signals indicative of a database of features scanned from said substrate; a means for grouping said scanned database signals into a plurality of signal arrays corresponding to tile regions of said substrate; a means for comparing a preferred tile region signal array with a corresponding scanned tile region; a means for generating distortion vector signals indicative of a variation in scanned pixel location from said preferred pixel location; and a means for generating signals for presentation to said AOI system for removing said pixel location variation during substrate defect detection.
Claim 9
Dependent Claim
185 words
A substrate distortion compensation apparatus for use in an automatic optical inspection (AOI) system, said apparatus comprising: a means for receiving pixel signals indicative of a database of features of preferred dimension and location to be fabricated on said substrate, said preferred dimension database signals including signals corresponding to pixels spaced across said substrate in a sequence of scan lines, with said features demarked by pixel state transitions; a means for grouping said preferred dimension database signals into a plurality of signal arrays corresponding to tile regions of said substrate; a means for receiving pixel signals indicative of a database of features scanned from said substrate; a means for grouping said scanned database signals into a plurality of signal arrays corresponding to tile regions of said substrate; a means for comparing a preferred tile region signal array with a corresponding scanned tile region; a means for generating distortion vector signals indicative of a variation in scanned pixel location from said preferred pixel location; and a means for generating signals for presentation to said AOI system for removing said pixel location variation during substrate defect detection.
Claim 10
Dependent Claim
39 words
The apparatus of claim 7 wherein said preferred dimension database signal grouping step further comprises the steps of grouping said preferred dimension tile region signals into arrays having dimensions, in pixels, greater than said scanned tile region signal arrays.
Claim 11
Dependent Claim
91 words
The apparatus of claim 7 wherein said scanned and preferred tile regions each comprise a center pixel, said apparatus further comprising: a means for centering said scanned and preferred tile region signal arrays about said center pixels; a means for adjusting said preferred tile region pixel signal array position relative to said scanned pixel signal array by at least one pixel; and a means for determining if said adjusted preferred tile region pixel array position yields a lesser magnitude of said variation than said centered preferred tile region pixel array position.
Claim 12
Dependent Claim
30 words
The apparatus of claim 9 further comprising a means for computing histogram signals indicative of a total value of feature enabled pixels across a one of said tile region dimensions.
Claim 13
Dependent Claim
22 words
The apparatus of claim 10 further comprising a means for generating said histogram signals for each orthogonal direction of said tile regions.
Claim 14
Dependent Claim
39 words
The apparatus of claim 11 further comprising a means for selecting an adjusted tile region pixel array position in dependence on which of said adjusted tile region pixel array positions yields maximum correlation in said computed histogram total values.
Claim 15
Dependent Claim
170 words
An article inspected using a method of substrate distortion compensation in an automatic optical inspection (AOI) system, said method comprising the steps of: receiving pixel signals indicative of a database of features of preferred dimension and location to be fabricated on said substrate, said preferred dimension database signals including signals corresponding to pixels spaced across said substrate in a sequence of scan lines, with said features demarked by pixel state transitions; grouping said preferred dimension database signals into a plurality of signal arrays corresponding to tile regions of said substrate; receiving pixel signals indicative of a database of features scanned from said substrate; grouping said scanned database signals into a plurality of signal arrays corresponding to tile regions of said substrate; comparing a preferred tile region signal array with a corresponding scanned tile region; generating distortion vector signals indicative of a variation in scanned pixel location from said preferred pixel location; and generating signals for presentation to said AOI system for removing said pixel location variation during substrate defect detection.
Claim 16
Dependent Claim
170 words
An article inspected using a method of substrate distortion compensation in an automatic optical inspection (AOI) system, said method comprising the steps of: receiving pixel signals indicative of a database of features of preferred dimension and location to be fabricated on said substrate, said preferred dimension database signals including signals corresponding to pixels spaced across said substrate in a sequence of scan lines, with said features demarked by pixel state transitions; grouping said preferred dimension database signals into a plurality of signal arrays corresponding to tile regions of said substrate; receiving pixel signals indicative of a database of features scanned from said substrate; grouping said scanned database signals into a plurality of signal arrays corresponding to tile regions of said substrate; comparing a preferred tile region signal array with a corresponding scanned tile region; generating distortion vector signals indicative of a variation in scanned pixel location from said preferred pixel location; and generating signals for presentation to said AOI system for removing said pixel location variation during substrate defect detection.
Claim 17
Independent Claim
154 words
A method for use in calibrating PCB fabrication apparatus comprising the steps of: generating a calibration substrate having features of preferred dimension and location, said features including pixels spaced across said calibration substrate in a sequence of scan lines, with said features demarked by pixel state transitions; receiving pixel signals indicative of a database of features of preferred dimension and location to be fabricated on said calibration substrate receiving pixel signals indicative of a database of features scanned from said calibration substrate; grouping said scanned database signals into a plurality of signal arrays corresponding to tile regions of said substrate; comparing a preferred tile region signal array with a corresponding scanned tile region; generating, for presentation to said PCB fabrication apparatus, distortion vector signals indicative of a variation in scanned pixel location from said preferred pixel location; and generating for presentation to said PCB fabrication apparatus calibration signals that remove said pixel location variation.
Claim 18
Independent Claim
154 words
A method for use in calibrating PCB fabrication apparatus comprising the steps of: generating a calibration substrate having features of preferred dimension and location, said features including pixels spaced across said calibration substrate in a sequence of scan lines, with said features demarked by pixel state transitions; receiving pixel signals indicative of a database of features of preferred dimension and location to be fabricated on said calibration substrate receiving pixel signals indicative of a database of features scanned from said calibration substrate; grouping said scanned database signals into a plurality of signal arrays corresponding to tile regions of said substrate; comparing a preferred tile region signal array with a corresponding scanned tile region; generating, for presentation to said PCB fabrication apparatus, distortion vector signals indicative of a variation in scanned pixel location from said preferred pixel location; and generating for presentation to said PCB fabrication apparatus calibration signals that remove said pixel location variation.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-04-09 | 1999-10-09 | 2000-04-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-04-09 | 2003-10-09 | 2004-04-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-04-09 | 2007-10-09 | 2008-04-09 | $7700.00 | Window Closed / Lapsed |