Inspection apparatus for detecting defects in a web

Claim 2

In apparatus for inspecting a moving web, the combination comprising: a scanner for repetitively scanning said moving web including means for illuminating a plurality of web sections across the width of said web on each scan, and detection means for generating intensity signals with amplitudes representing the light transmitted through, or reflected from, each illuminated section of said web; means for converting the intensity signals generated by said detection means, in response to the repeated illumination of each web section during a plurality of web scans, as a first length of said web passes said scanner, into sets of data representing the normal ranges of variation in selected characteristics of the intensity signals associated with each section of said moving web; means for storing said sets of data; and means for comparing said selected characteristics of each intensity signal generated by said detection means during a scan, as a second length of said web passes said scanner, with the set of stored data representing the normal ranges of variation in said selected characteristics for the intensity signal.

Claim 3

The apparatus of claim 1 wherein said means for converting generates a set of data representing the normal range of variation in signal amplitude for each set of intensity signals generated in response to the repetitive illumination of a section of said web as said first length of said web passes said scanner.

Claim 4

The apparatus of claim 1 wherein said means for converting generates a set of data representing the normal range of variation in the scan-to-scan difference in signal amplitude for each set of intensity signals generated in response to the repetitive illumination of a section of said web as said first length of said web passes said scanner.

Claim 5

In apparatus for inspecting a moving web, the combination comprising: means for periodically illuminating selected sections of said web in sequence; means for generating signals with amplitudes representing the intensity of the light transmitted through, or reflected from, each of the illuminated sections of said web; amplitude comparator means for determining if the amplitudes of signals generated in response to the periodic illumination of a section of said web are within the normal range of stored signal amplitudes generated by said means for generating as a result of periodically illuminating the same section of a defect-free web; and signalling means responsive to said amplitude comparator for generating a defect signal when the amplitudes of one of said signals is outside of said normal range of signal amplitudes.

Claim 6

In apparatus for inspecting a moving web, the combination comprising: means for periodically illuminating selected sections of said web in sequence; means for generating signals with amplitudes representing the intensity of the light transmitted through, or reflected from, each of the illuminated sections of said web; amplitude comparator means for determining if the amplitudes of signals generated in response to the periodic illumination of a section of said web are within the normal range of stored signal amplitudes generated by said means for generating as a result of periodically illuminating the same section of a defect-free web; and signalling means responsive to said amplitude comparator for generating a defect signal when the amplitudes of one of said signals is outside of said normal range of signal amplitudes.

Claim 7

The apparatus of claim 4, further comprising: a difference comparator for determining if the difference in amplitude of signals generated in response to two successive illuminations of a section of said web is within the normal range of such differences obtained when the same section of a defect-free web is periodically illuminated; wherein said signalling means is further responsive to said difference comparator for generating a defect signal when said difference in signal amplitude is outside of said normal range of such differences.

Claim 8

The apparatus of claim 4 wherein said means for periodically illuminating selected sections of said web further comprises: a plurality of light emitting diodes arranged in a pattern extending across the width of said web; and means for repetitively pulsing said light emitting diodes in sequence to illuminate said selected sections of said web.

Claim 9

In apparatus for inspecting a moving web, the combination comprising: means for repetitively illuminating selected discrete sections of said web in sequence for selected intervals; detection means for generating signals with amplitudes representing the intensity of the light transmitted through, or reflected from, each illuminated section of said web; storage means containing predetermined amplitude data representing normal ranges of signal amplitudes resulting from the repetitive illumination of each of said selected sections on a defect-free web of the same type as said web; an amplitude comparator for comparing the amplitudes of the signals generated in response to repetitive illumination of a section of said web with the stored amplitude data representing the normal range of signal amplitudes for this section of said web; and signalling means responsive to said amplitude comparator for generating a first defect signal when said signal amplitude is outside of said normal range of amplitudes.

Claim 10

In apparatus for inspecting a moving web, the combination comprising: means for repetitively illuminating selected discrete sections of said web in sequence for selected intervals; detection means for generating signals with amplitudes representing the intensity of the light transmitted through, or reflected from, each illuminated section of said web; storage means containing predetermined amplitude data representing normal ranges of signal amplitudes resulting from the repetitive illumination of each of said selected sections on a defect-free web of the same type as said web; an amplitude comparator for comparing the amplitudes of the signals generated in response to repetitive illumination of a section of said web with the stored amplitude data representing the normal range of signal amplitudes for this section of said web; and signalling means responsive to said amplitude comparator for generating a first defect signal when said signal amplitude is outside of said normal range of amplitudes.

Claim 11

The apparatus of claim 7, further comprising: storage means containing predetermined amplitude difference data representing the normal ranges of variation in the scan-to-scan difference in amplitudes of signals resulting from the repetitive illumination of each of said sections on a defect-free web of the same type as said web; means for determining the scan-to-scan difference in amplitude of signals generated by said detection means in response to repetitive illumination of each section of said web; an amplitude difference comparator for comparing the determined scan-to-scan amplitude difference for a section of said web with the stored amplitude difference data representing the normal range of such amplitude differences for this section of said web; wherein said signalling means is further responsive to said amplitude difference comparator for generating a second defect signal when said determined scan-to-scan amplitude difference is outside of said normal range of such differences.

Claim 12

In apparatus for inspecting a moving web, the combination comprising: illumination means for repetitively scanning the width of said web over a path with a length greater than the width of said web; detection means for generating signals with amplitudes representing the intensity of the light transmitted through, or reflected from, selected areas illuminated during said scanning; means for determining the average amplitude of each set of signals generated in response to the repetitive illumination of each of said areas during a selected number of scans; means responsive to the determined average amplitudes for limiting the scan width to the width of said web; and defect detection means responsive to signals generated by said detection means during the limited width scans for indicating the presence of defects in said web.

Claim 13

In apparatus for inspecting a moving web, the combination comprising: illumination means for repetitively scanning the width of said web over a path with a length greater than the width of said web; detection means for generating signals with amplitudes representing the intensity of the light transmitted through, or reflected from, selected areas illuminated during said scanning; means for determining the average amplitude of each set of signals generated in response to the repetitive illumination of each of said areas during a selected number of scans; means responsive to the determined average amplitudes for limiting the scan width to the width of said web; and defect detection means responsive to signals generated by said detection means during the limited width scans for indicating the presence of defects in said web.

Claim 14

The apparatus of claim 9 wherein said defect detection means further comprises: amplitude comparator means for determining if the amplitudes of said signals generated in response to the repetitive illumination of a selected one of said areas during said limited width scanning are outside a predetermined range of amplitudes; and means responsive to said amplitude comparator for generating a defect signal when the amplitude of one of said signals is outside said predetermined range of amplitudes.

Claim 15

The apparatus of claim 9 wherein said defect detection means further comprises: means for determining if, during the limited width scanning, the scan-to-scan difference in the amplitudes of signals generated on two successive illuminations of a section of said web is outside a predetermined range of such differences; and means responsive to said means for determining for generating a defect signal when the determined difference is outside said predetermined range of such differences.

Claim 16

In apparatus for inspecting a moving web by repetitively scanning said web, the combination comprising: a plurality of light emitting diodes aligned transverse to the direction of travel of said web and positioned to illuminate selected sections of said web when activated; means for periodically activating selected ones of said light emitting diodes to intermittently illuminate discrete sections of said web; means responsive to the light transmitted through, or reflected from, each illuminated section of said web for generating a signal with an amplitude representing the intensity of the light emanating from said illuminated section; comparison means for determining if said amplitude of said signal falls with a predetermined range of amplitudes that is related to the variation in signal amplitudes generated when said section of a defect-free web is repetitively illuminated; and means responsive to said comparison means for generating a defect signal when the amplitude of said signal is outside of said predetermined range of amplitudes.

Claim 17

In apparatus for inspecting a moving web by repetitively scanning said web, the combination comprising: a plurality of light emitting diodes aligned transverse to the direction of travel of said web and positioned to illuminate selected sections of said web when activated; means for periodically activating selected ones of said light emitting diodes to intermittently illuminate discrete sections of said web; means responsive to the light transmitted through, or reflected from, each illuminated section of said web for generating a signal with an amplitude representing the intensity of the light emanating from said illuminated section; comparison means for determining if said amplitude of said signal falls with a predetermined range of amplitudes that is related to the variation in signal amplitudes generated when said section of a defect-free web is repetitively illuminated; and means responsive to said comparison means for generating a defect signal when the amplitude of said signal is outside of said predetermined range of amplitudes.

Claim 18

The apparatus of Claim 12 wherein said means responsive to light transmitted through, or reflected from, each illuminated section of said web further comprises: a plurality of photosensors aligned transverse to the direction of travel of said web, each being positioned to intercept light emanating from one of said sections of said web when said section is illuminated; and means for converting the analog signals generated by said photosensors into digital codes.

Claim 19

The apparatus of claim 12, further comprising: means for determining the difference between the amplitudes of signals generated by illuminating a selected section of said web on two successive scans; a second comparison means for determining if the difference in signal amplitudes falls within a predetermined range of amplitude differences that is related to the variation of such amplitude differences which occur when said section of a defect-free web is repetitively illuminated; and means responsive to said second comparison means for generating a defect signal when said amplitude difference falls outside of said predetermined range of amplitude differences.

Claim 20

In apparatus for inspecting a moving web, the combination comprising: a plurality of light emitting diodes aligned transverse to the direction of travel of said web and positioned to illuminate selected sections of said web when activated; a plurality of photosensors aligned transverse to the direction of travel of said web, each being positioned to intercept light emanating from one of said sections of said web when said section is illuminated; means for sequentially activating said light emitting diodes to produce repetitive scans of said web; means for converting the photosensor output signal resulting from the illumination of a selected section of said web during a first scan into a first digital amplitude code; means for storing said first digital amplitude code; storage means containing sets of digital amplitude data, each of said sets of amplitude data representing a range of amplitudes associated with one of said web sections; a first comparator for comparing said first digital amplitude code generated as a result of illuminating said selected web section with the set of amplitude data representing the range of amplitudes associated with said selected web section; and means responsive to said comparator for generating a defect signal when said first digital amplitude code is not within the amplitude range represented by said set of amplitude data associated with said selected web section.

Claim 21

In apparatus for inspecting a moving web, the combination comprising: a plurality of light emitting diodes aligned transverse to the direction of travel of said web and positioned to illuminate selected sections of said web when activated; a plurality of photosensors aligned transverse to the direction of travel of said web, each being positioned to intercept light emanating from one of said sections of said web when said section is illuminated; means for sequentially activating said light emitting diodes to produce repetitive scans of said web; means for converting the photosensor output signal resulting from the illumination of a selected section of said web during a first scan into a first digital amplitude code; means for storing said first digital amplitude code; storage means containing sets of digital amplitude data, each of said sets of amplitude data representing a range of amplitudes associated with one of said web sections; a first comparator for comparing said first digital amplitude code generated as a result of illuminating said selected web section with the set of amplitude data representing the range of amplitudes associated with said selected web section; and means responsive to said comparator for generating a defect signal when said first digital amplitude code is not within the amplitude range represented by said set of amplitude data associated with said selected web section.

Claim 22

The apparatus of claim 15 wherein a second digital amplitude code is generated in response to the illumination of said selected web secTion on a second scan of said web, further comprising: means for generating a digital amplitude difference code representing the difference between the amplitudes represented by said second digital amplitude code and the stored first digital amplitude code; storage means containing sets of digital amplitude difference data, each of said sets of amplitude difference data representing a range of amplitude differences associated with one of said sections of said web; a second comparator for comparing said digital amplitude difference code with the set of data representing a range of amplitude differences associated with said selected web section; and means responsive to said second comparator for generating a defect signal when said digital amplitude difference code is not within the range of amplitude differences represented by said set of digital amplitude difference data associated with said selected web section.