US4477926A — Process for inspecting and automatically sorting …

Claim 1

Independent Claim 203 words

A process for inspecting and automatically sorting objects showing patterns provided with constant dimensional tolerances, of the type including the comparison of image I ref of a reference object with image I exa of an object to be inspected, wherein image I exa being able to show geometrical defects with respect to the reference object, said process characterized in that it includes the following steps: Step 1, processing images I ref and I exa to provide electronic binary images I REF and I EXA , respectively, Step 2, defining a structuring element B for each image point of the said electronic binary image and adapted to the dimensional tolerances of the said object to be inspected and the construction of the electronic images I REF max and I REF min which consist in image I REF expanded and eroded respectively by structuring element B, Step 3, forming the images of the "spreading" or "lack" type defects by respectively carrying out the following logic operations: [I.sub.REF max OR I.sub.EXA ] EXC. OR I.sub.REF max and [I.sub.REF min OR I.sub.EXA ] EXC. OR I.sub.EXA and Step 4, analyzing the defects with respect to a reject criterion which defines a maximum allowed size for the defects.

Claim 2

Dependent Claim 203 words

A process for inspecting and automatically sorting objects showing patterns provided with constant dimensional tolerances, of the type including the comparison of image I ref of a reference object with image I exa of an object to be inspected, wherein image I exa being able to show geometrical defects with respect to the reference object, said process characterized in that it includes the following steps: Step 1, processing images I ref and I exa to provide electronic binary images I REF and I EXA , respectively, Step 2, defining a structuring element B for each image point of the said electronic binary image and adapted to the dimensional tolerances of the said object to be inspected and the construction of the electronic images I REF max and I REF min which consist in image I REF expanded and eroded respectively by structuring element B, Step 3, forming the images of the "spreading" or "lack" type defects by respectively carrying out the following logic operations: [I.sub.REF max OR I.sub.EXA ] EXC. OR I.sub.REF max and [I.sub.REF min OR I.sub.EXA ] EXC. OR I.sub.EXA and Step 4, analyzing the defects with respect to a reject criterion which defines a maximum allowed size for the defects.

Claim 3

Dependent Claim 36 words

Inspecting and sorting process as set forth in claim 1 characterized in that the maximum allowed size is determined by the calculation of the horizontal and vertical projections of the defects which define an analysis window.

Claim 4

Dependent Claim 54 words

Inspecting and sorting process as set forth in claim 1, characterized in that the step 2 provided for constructing images I REF and I EXA comprises: picking up images I ref and I exa of the reference object and of the object to be inspected, and thresholding the images to obtain electronic binary images.

Claim 5

Dependent Claim 69 words

Inspecting and sorting process as set forth in claim 1, characterized in that the step 2 provided for constructing images I REF and I EXA comprises: picking up image I exa of the object to be inspected and thresholding this image to obtain an electronic binary image I EXA , directly constructing the reference object in binary mode either from a digital pattern generator or from a data bank.

Claim 6

Dependent Claim 42 words

Inspecting and sorting process as set forth in claim 3 characterized in that it further includes a step for centering electronic images I REF and I EXA , which corresponds to the optical centering of images I ref and I exa .

Claim 7

Dependent Claim 28 words

Inspecting and sorting process as set forth in claim 3 characterized in that the image picking up step provides analog images including black and white and grey levels.

Claim 8

Dependent Claim 41 words

Inspecting and sorting process as set forth in claim 6 characterized in that the picking up step further includes a step for discretizing the image to retain only a number 2 N of grey levels, N being between 2 and 6.

Claim 9

Dependent Claim 47 words

Inspecting and sorting process as set forth in claim 7 characterized in including an image point intensity frequency curve and wherein the thresholding step includes the threshold determination which is performed from the image point intensity frequency curve, said determination being carried out by using a program.

Claim 10

Dependent Claim 84 words

Inspecting and sorting process as set forth in claim 3 characterized in that it further includes a step for cleaning images I REF and I EXA (noise suppression), performed prior to the defect image forming step, and consisting in an erode operation, the size of the structuring element which is to erode the image being smaller than the size of the smallest defect which is to be detected, followed by an expand operation which returns the image to its size prior to said erosion.

Claim 11

Dependent Claim 214 words

Apparatus for carrying out the process for inspecting and automatically sorting objects showing patterns with constant dimensional tolerances, of the type including the comparison of image I ref of a reference object with image I exa of an object to be inspected, wherein image I exa being able to show geometrical defects with respect to the reference object, characterized in that it includes: means for processing images I ref and I exa to provide electronic binary images I REF and I EXA , respectively, means for picking up at least image I exa of the object to be inspected, means for constructing binary electronic images I REF and I EXA , processing means including means for constructing electronic images I REF max and I REF min, respectively, which are the images of I REF expanded and eroded respectively by a previously determined structuring element B and directly linked to the dimensional tolerances of said patterns, compare means for constructing the images of the "lack" and "spreading" type defects by performing the following logic operations: [I.sub.REF max OR I.sub.EXA ] EXCL. OR I.sub.REF max and [I.sub.REF min OR I.sub.EXA ] EXCL. OR I.sub.EXA, and means for analyzing defects with repect to predetermined reject criteria and means for sorting and selecting the objects which are accepted.

Claim 12

Dependent Claim 214 words

Apparatus for carrying out the process for inspecting and automatically sorting objects showing patterns with constant dimensional tolerances, of the type including the comparison of image I ref of a reference object with image I exa of an object to be inspected, wherein image I exa being able to show geometrical defects with respect to the reference object, characterized in that it includes: means for processing images I ref and I exa to provide electronic binary images I REF and I EXA , respectively, means for picking up at least image I exa of the object to be inspected, means for constructing binary electronic images I REF and I EXA , processing means including means for constructing electronic images I REF max and I REF min, respectively, which are the images of I REF expanded and eroded respectively by a previously determined structuring element B and directly linked to the dimensional tolerances of said patterns, compare means for constructing the images of the "lack" and "spreading" type defects by performing the following logic operations: [I.sub.REF max OR I.sub.EXA ] EXCL. OR I.sub.REF max and [I.sub.REF min OR I.sub.EXA ] EXCL. OR I.sub.EXA, and means for analyzing defects with repect to predetermined reject criteria and means for sorting and selecting the objects which are accepted.

Claim 13

Dependent Claim 34 words

Apparatus as set forth in claim 10 characterized in that pick up means are chosen from the group consisting of the electron microscopes, the TV cameras, the photodiode array and the charge coupled devices.

Claim 14

Dependent Claim 29 words

Apparatus as set forth in claim 10 characterized in that said means for constructing binary electronic images I REF and I EXA comprise a threshold detection and thresholding unit.

Claim 15

Dependent Claim 25 words

Apparatus as set forth in claim 10, characterized in that it further includes: compute means for recentering electronic images I REF and I EXA .

Claim 16

Dependent Claim 58 words

Apparatus as set forth in claim 10 characterized in that said reject criteria are based upon the maximum allowed projections of the defect image on axis x and y, in order to check that a defect can be accepted only if it is really contained within an analysis window the sides of which correspond to said maximum projections.

Claim 17

Dependent Claim 21 words

Apparatus as set forth in claim 10 characterized in that it further includes a digital computer which controls all said means.

Claim 18

Dependent Claim 31 words

Apparatus or process as set forth in claim 10 characterized in that said objects consist of modules showing a pattern of conducting lines provided on the surface of a ceramic substrate.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1987-10-16	1988-04-16	1988-10-16	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1991-10-16	1992-04-16	1992-10-16	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1995-10-16	1996-04-16	1996-10-16	$7700.00	Window Closed / Lapsed

Process for inspecting and automatically sorting objects showing patterns with constant dimensional tolerances and apparatus for carrying out said process

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