EP0186278A2 — Detecting defects in transparent articles

Claim 1

Independent Claim 120 words

Apparatus for detecting defects in transparent articles, comprising: means (40, 42, 44, 50) for scanning a beam of light so that the beam traverses different portions of an article on successive scans; optical means (52) for projecting light passing through the article onto a diffusing screen (54); a plurality of photodetectors (62, 64, 66, 68) disposed adjacent said screen (54) for respectively detecting the intensity of light projected onto different predetermined areas of said screen (54); threshold detection means (78, 80, 82) connected to said photodetectors (62, 64, 66, 68) for determining when the intensity of light detected by each of said photodetectors crosses respective thresholds; and means (96, 98) responsive to said threshold detection for generating a reject signal.

Claim 2

Dependent Claim 120 words

Apparatus for detecting defects in transparent articles, comprising: means (40, 42, 44, 50) for scanning a beam of light so that the beam traverses different portions of an article on successive scans; optical means (52) for projecting light passing through the article onto a diffusing screen (54); a plurality of photodetectors (62, 64, 66, 68) disposed adjacent said screen (54) for respectively detecting the intensity of light projected onto different predetermined areas of said screen (54); threshold detection means (78, 80, 82) connected to said photodetectors (62, 64, 66, 68) for determining when the intensity of light detected by each of said photodetectors crosses respective thresholds; and means (96, 98) responsive to said threshold detection for generating a reject signal.

Claim 3

Dependent Claim 81 words

Apparatus as claimed in Claim 1, wherein the threshold detection means includes threshold detection and counting means (70, 80, 82) connected to the photodetectors (62, 64, 66, 68) for determining the number of times the intensity of light detected by each of the photodetectors crosses respective thresholds, and the means (96, 98) responsive to the threshold detection and counting means is operable to generate a reject signal when said number of times is at least equal to a predetermined criterion value.

Claim 4

Dependent Claim 39 words

Apparatus as claimed in Claim 1 or Claim 2, including means (46) for synchronizing the threshold detection with the scanning means so that said determination takes place only as the light beam traverses a predetermined portion of the article.

Claim 5

Dependent Claim 63 words

Apparatus as claimed in any one of Claims 1 to 3, wherein the scanning means (40, 42, 44, 50) is operable to scan the light beam in a first direction, and a conveyor (12) is operable to move the article relative to the scanned beam in a second direction so that the light beam traverses different portions of the article on successive scans.

Claim 6

Dependent Claim 48 words

Apparatus as claimed in any one of Claims 1 to 4, further including a chamber (56) disposed adjacent to said screen (54), said chamber (56) being divided into a plurality of cells with at least one of said photodetectors (62, 64, 66, 68) being located in each cell.

Claim 7

Dependent Claim 49 words

Apparatus as claimed in Claim 2, wherein the threshold detection and counting means includes first means (78) for counting the number of times a threshold is crossed during each scan of the beam and second means (92) for counting the number of scans during which the threshold is crossed.

Claim 8

Dependent Claim 23 words

Apparatus as claimed in Claim 6, wherein said second means (92) counts the number of consecutive scans during which the threshold is crossed.

Claim 9

Dependent Claim 44 words

Apparatus as claimed in Claim 6 or Claim 7, including means (46) for synchronizing the counting means with the scanning means, which synchronizing means (46) selectively enables one of said first and second counting means (78, 92) during scanning of the beam of light.

Claim 10

Dependent Claim 40 words

Apparatus as claimed in any one of Claims 1 to 8, wherein the optical means includes a lens (52) for focussing all light which passes through an article unimpeded by a defect onto a predetermined area on the screen (54).

Claim 11

Dependent Claim 79 words

Apparatus as claimed in Claim 6, wherein at least one of said threshold detection means (78) and an associated photodetector (64, 66, 68) is responsive to a decrease in the intensity of light projected onto said predetermined are a on said screen (54) to generate a flaw signal, and another of said threshold detection means (78) is responsive to the projection of light onto a portion of the screen (54) outside of said area to generate a flaw signal.

Claim 12

Dependent Claim 40 words

Apparatus as claimed in any one of Claims 1 to 10, further including means (82) for dynamically varying at least one of said thresholds during each scan of said beam in accordance with the portion of the article being scanned.

Claim 13

Dependent Claim 46 words

Apparatus as claimed in any one of Claims 1 to 10, further including means (82) for adjusting said thresholds in response to changes in the detected intensity of the laser beam during a portion of its scan in which it does not pass through an article.

Claim 14

Dependent Claim 188 words

Apparatus for inspecting a transparent container to detect the presence of a flaw, comprising: means (12) for continuously moving a container along a path of travel; a first inspection zone (14) including means (40, 42, 44, 50) for scanning a portion of the container with a beam of light, means (52) for collecting light passing through the container and focussing it upon a screen (54), means (62, 64, 66, 68, 78) for detecting the location and intensity of light focussed on the screen, and means (96, 98) for processing the detected light to generate a first reject signal; container rotating means (22) located downstream of said first inspection zone (14) for rotating said container 90 0 about its longitudinal axis; and a second inspection zone (32) located downstream of said rotating means (22) and including means for scanning a portion of the container with a beam of light, means for collecting light passing through the container and focussing it upon a screen, means for detecting the location and intensity of light focussed on the screen, and means for processing the detected light to generate a second reject signal.

Claim 15

Dependent Claim 188 words

Apparatus for inspecting a transparent container to detect the presence of a flaw, comprising: means (12) for continuously moving a container along a path of travel; a first inspection zone (14) including means (40, 42, 44, 50) for scanning a portion of the container with a beam of light, means (52) for collecting light passing through the container and focussing it upon a screen (54), means (62, 64, 66, 68, 78) for detecting the location and intensity of light focussed on the screen, and means (96, 98) for processing the detected light to generate a first reject signal; container rotating means (22) located downstream of said first inspection zone (14) for rotating said container 90 0 about its longitudinal axis; and a second inspection zone (32) located downstream of said rotating means (22) and including means for scanning a portion of the container with a beam of light, means for collecting light passing through the container and focussing it upon a screen, means for detecting the location and intensity of light focussed on the screen, and means for processing the detected light to generate a second reject signal.

Claim 16

Dependent Claim 89 words

Apparatus as claimed in Claim 13, wherein the container moving means is a conveyor (12) and the container rotating means (22) includes a pair of belts (24, 26) respectively disposed on opposite sides and parallel to the conveyor (12) for engaging a container as it passes between them on the conveyor, and means for moving one of said belts faster than said conveyor and moving the other of said belts slower than said conveyor so as to rotate the container as it moves at the speed of said conveyor.

Claim 17

Independent Claim 98 words

A method for detecting the presence of a fault in a transparent container, comprising the steps of: scanning a beam of light across the container; focussing light passing through the container onto a screen; detecting the intensity of light falling on different predetermined portions of the screen; comparing the detected intensity with a predetermined threshold; - counting the number of times that the detected light intensity crosses the threshold during scanning of the beam; and generating a signal to indicate the presence of a fault when said number of times is at least equal to a predetermined value.

Claim 18

Independent Claim 98 words

A method for detecting the presence of a fault in a transparent container, comprising the steps of: scanning a beam of light across the container; focussing light passing through the container onto a screen; detecting the intensity of light falling on different predetermined portions of the screen; comparing the detected intensity with a predetermined threshold; - counting the number of times that the detected light intensity crosses the threshold during scanning of the beam; and generating a signal to indicate the presence of a fault when said number of times is at least equal to a predetermined value.

Claim 19

Dependent Claim 40 words

A method as claimed in Claim 15, further including the step of synchronizing said comparing step with the scanning of the beam so that said comparing takes place only while said beam is traversing a predetermined area on the container.

Claim 20

Dependent Claim 60 words

A method as claimed in Claim 15 or Claim 16, wherein said light is focussed onto the screen in a manner such that all light which passes through the container unaffected by a flaw is projected onto one portion of the screen and light which is refracted or dispersed by a flaw is projected onto another portion of the screen.

Detecting defects in transparent articles

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