US4484081A — Defect analysis system

Claim 1

Independent Claim 152 words

A defect analysis system for examining a part to determine whether defects are present, said system comprising: first means for obtaining electrical signals representative of the condition of a plurality of discrete picture elements in a field of view of the part presented for analysis; thresholding means coupled to said first means for generating a set of electrical signals indicative of picture elements of an anomalous type distinct from the other picture elements; region growing means for associating contiguous picture elements of the anomalous type to define multiple regions of anomalous picture elements in a single raster scan of the field of view being analyzed; region statistics generation means for generating statistics relative to the size, shape and orientation of the anomalous regions during the same single raster scan; and region analysis means for comparing the region statistics with predetermined rejection parameters to determine whether a rejectable defect exists in the part.

Claim 2

Dependent Claim 152 words

A defect analysis system for examining a part to determine whether defects are present, said system comprising: first means for obtaining electrical signals representative of the condition of a plurality of discrete picture elements in a field of view of the part presented for analysis; thresholding means coupled to said first means for generating a set of electrical signals indicative of picture elements of an anomalous type distinct from the other picture elements; region growing means for associating contiguous picture elements of the anomalous type to define multiple regions of anomalous picture elements in a single raster scan of the field of view being analyzed; region statistics generation means for generating statistics relative to the size, shape and orientation of the anomalous regions during the same single raster scan; and region analysis means for comparing the region statistics with predetermined rejection parameters to determine whether a rejectable defect exists in the part.

Claim 3

Dependent Claim 30 words

A defect analysis system as set forth in claim 1, wherein: said region statistics generation means includes means for recording the position, area, length-to-width ratio and orientation of each region.

Claim 4

Dependent Claim 70 words

A defect analysis system as set forth in claim 2, wherein said region analysis means includes: means for comparing the area of a region with a first preselected limit wherein regions smaller in area than the first preselected limit are disregarded; and means for comparing the area of a region with a second preselected minimum area, wherein regions larger than the second preselected minimum area are designated as rejectable defects.

Claim 5

Dependent Claim 46 words

A defect analysis system as set forth in claim 2, wherein said region analysis means includes: means for comparing the length-to-width ratio of a region with a preselected threshold ratio, wherein regions having a length-to-width ratio higher than the threshold ratio are designated as rejectable defects.

Claim 6

Dependent Claim 44 words

A defect analysis system as set forth in claim 2, wherein said region analysis means includes: means for comparing the spacing between and orientation of two regions with respective preselected spacing and orientation parameters to determine whether two regions together constitute a rejectable defect.

Claim 7

Dependent Claim 119 words

A defect analysis system as set forth in claim 5, wherein said means for comparing include: means for determining the centers of mass of the two regions; means for comparing the distance between the centers of mass of the two regions, with a preselected multiple of the length of one of the regions; means for comparing the difference in angular orientations of the regions with a preselected angle; and means for comparing the difference between the angular orientation of one region and the angular orientation of a line joining the centers of mass of both regions, with a preselected angle, wherein a rejectable defect occurs when the necessary distance and angle values are smaller than the corresponding preselected values.

Claim 8

Dependent Claim 112 words

A defect analysis system as set forth in claim 1, wherein: said system further includes a source of radiation directed to the part being examined; the condition of the picture elements that renders anomalous elements distinct is the intensity of radiation reflected from each element; and said thresholding means includes histogram calculation means for accumulating counts of picture elements for corresponding levels of radiation intensity, means for determining from the accumulated counts a threshold level of intensity above which a picture element will be considered to be anomalous, and image transformation means for comparing each picture element with the threshold level and thereby generating a binary image of the field of view.

Claim 9

Dependent Claim 31 words

A deflect analysis system as set forth in claim 7, wherein said histogram calculation means and said image transformation means are implemented in hard-wired form to increase the speed of operation.

Claim 10

Dependent Claim 163 words

A surface defect analysis system for examining a part to determine whether structural defects are present, said system comprising: a source of light directed to the part being examined; video camera means for obtaining analog electrical signals representative of the intensity of light emitted by discrete picture elements in an image frame of the part presented for analysis; thresholding means coupled to said video camera means, for generating binary electrical signals indicative of anomalous picture elements having light intensities substantially different from the other picture elements; region growing means for associating contiguous anomalous picture elements to define multiple regions of anomalous picture elements in a single raster scan of the image frame presented for analysis; region statistics generation means for generating statistics relative to the size, shape and orientation of the anomalous regions during the same single raster scan; and region analysis means for comparing the region statistics with predetermined rejection parameters, to determine whether a rejectable defect is present in the part.

Claim 11

Dependent Claim 163 words

A surface defect analysis system for examining a part to determine whether structural defects are present, said system comprising: a source of light directed to the part being examined; video camera means for obtaining analog electrical signals representative of the intensity of light emitted by discrete picture elements in an image frame of the part presented for analysis; thresholding means coupled to said video camera means, for generating binary electrical signals indicative of anomalous picture elements having light intensities substantially different from the other picture elements; region growing means for associating contiguous anomalous picture elements to define multiple regions of anomalous picture elements in a single raster scan of the image frame presented for analysis; region statistics generation means for generating statistics relative to the size, shape and orientation of the anomalous regions during the same single raster scan; and region analysis means for comparing the region statistics with predetermined rejection parameters, to determine whether a rejectable defect is present in the part.

Claim 12

Dependent Claim 31 words

A surface defect analysis system as set forth in claim 9, wherein: said region statistics generation means includes means for recording the position, area, length-to-width ratio and orientation of each region.

Claim 13

Dependent Claim 71 words

A surface defect analysis system as set forth in claim 10, wherein said region analysis means includes: means for comparing the area of a region with a first preselected limit, wherein regions smaller in area than the first preselected limit are disregarded; and means for comparing the area of a region with a second preselected limit wherein regions larger in area than the second preselected limit are designated as rejectable defects.

Claim 14

Dependent Claim 47 words

A surface defect analysis system as set forth in claim 10, wherein said region analysis means includes: means for comparing the length-to-width ratio of a region with a preselected threshold ratio, wherein regions having a length-to-width ratio higher than the threshold ratio are designated as rejectable defects.

Claim 15

Dependent Claim 45 words

A surface defect analysis system as set forth in claim 10, wherein said region analysis means includes: means for comparing the spacing between and orientation of two regions with respective preselected spacing and orientation parameters to determine whether two regions together constitute a rejectable defect.

Claim 16

Dependent Claim 108 words

A surface defect analysis system as set forth in claim 13, wherein said means for comparing include: means for comparing the distance between the centers of mass of the two regions, with a preselected multiple of the length of one of the regions; means for comparing the difference in angular orientations of the regions with a preselected angle; means for comparing the difference between the angular orientation of one region and the angular orientation of a line joining the centers of mass of both regions, within a preselected angle, wherein a rejectable defect occurs when the necessary distance and angle values are smaller than the corresponding preselected values.

Claim 17

Dependent Claim 74 words

A surface defect analysis system as set forth in claim 9, wherein said thresholding means includes histogram calculation means for accumulating counts of picture elements for corresponding levels of light intensity, means for determining from the accumulated counts a threshold level of intensity above which a picture element will be considered to be anomalous, and image transformation means for comparing each picture element with the threshold level and thereby generating a binary frame image.

Claim 18

Dependent Claim 32 words

A surface defect analysis system as set forth in claim 15, wherein said histogram calculation means and said image transformation means are implemented in hard-wired form to increase the speed of operation.

Claim 19

Dependent Claim 59 words

A surface defect analysis system as set forth in claim 15, wherein said means for determining a threshold level includes: means for comparing the ratio of two adjacent histogram values with a preselected ratio; and means for designating a histogram value the threshold level based on the results obtained from two successive comparison operations by said means for comparing.

Claim 20

Dependent Claim 17 words

A surface defect analysis system as set forth in claim 17, wherein said preselected ratio is 0.5.

Claim 21

Independent Claim 115 words

A method for detection of defects in a manufactured part, comprising the steps of: obtaining electrical signals representative of a plurality of picture elements in a field of view of a part presented for inspection; transforming these signals into a set of binary electrical signals indicative of anomalous picture elements that are optically distinct from other picture elements; associating contiguous anomalous picture elements to define multiple regions of anomalous picture elements in a single raster scan of the field of view presented for inspection; generating statistics relative to physical characteristics of each region during the same single raster scan; and comparing region statistics with predetermined rejection parameters to determine whether a rejectable defect is present.

Claim 22

Independent Claim 115 words

A method for detection of defects in a manufactured part, comprising the steps of: obtaining electrical signals representative of a plurality of picture elements in a field of view of a part presented for inspection; transforming these signals into a set of binary electrical signals indicative of anomalous picture elements that are optically distinct from other picture elements; associating contiguous anomalous picture elements to define multiple regions of anomalous picture elements in a single raster scan of the field of view presented for inspection; generating statistics relative to physical characteristics of each region during the same single raster scan; and comparing region statistics with predetermined rejection parameters to determine whether a rejectable defect is present.

Claim 23

Dependent Claim 60 words

A method as set forth in claim 19, wherein said step of transforming the signals includes: generating a histogram of the entire image frame to define the relationship between light intensity and numbers of picture elements; calculating an optimum threshold level from the histogram; and generating a binary frame image by comparing each picture element intensity with the threshold level.

Claim 24

Dependent Claim 27 words

A method as set forth in claim 19, wherein: said step of generating statistics includes recording the size, position, length-to-width ratio, and angular orientation of each region.

Claim 25

Dependent Claim 39 words

A method as set forth in claim 21, wherein: said step of comparing region statistics with predetermined rejection parameters includes, comparing the area of each region with a preselected limit above which the region will be designated a defect.

Claim 26

Dependent Claim 40 words

A method as set forth in claim 21, wherein: said step of comparing region statistics with predetermined rejection parameters includes comparing the length-to-width ratio of each region with a preselected value, above which the region will be designated a defect.

Claim 27

Dependent Claim 64 words

A method as set forth in claim 21, wherein said step of comparing region statistics with predetermined rejection parameters includes: comparing the distance to each neighboring region with a preselected relative distance; and comparing the angular orientation of each region with that of each neighboring region, whereby a rejectable defect will be found if two regions are relatively close together and are substantially collinear.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1987-11-20	1988-05-21	1988-11-20	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1991-11-20	1992-05-21	1992-11-20	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1995-11-20	1996-05-21	1996-11-20	$7700.00	Window Closed / Lapsed

Defect analysis system

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