WO2020231683A1 - Procédés et appareil de test de résistance de bord - Google Patents

Procédés et appareil de test de résistance de bord Download PDF

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Publication number
WO2020231683A1
WO2020231683A1 PCT/US2020/031553 US2020031553W WO2020231683A1 WO 2020231683 A1 WO2020231683 A1 WO 2020231683A1 US 2020031553 W US2020031553 W US 2020031553W WO 2020231683 A1 WO2020231683 A1 WO 2020231683A1
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WO
WIPO (PCT)
Prior art keywords
sheet
region
edge
test
stress
Prior art date
Application number
PCT/US2020/031553
Other languages
English (en)
Inventor
Chong Pyung An
Gabriel Pierce AGNELLO
Zhenxing Hu
Bosun JANG
Peter Knowles
Balamurugan MEENAKSHI SUNDARAM
Douglas Miles NONI JR.
Richard Sean PRIESTLEY
Jamie Todd Westbrook
Original Assignee
Corning Incorporated
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Corning Incorporated filed Critical Corning Incorporated
Priority to JP2021568312A priority Critical patent/JP2022533625A/ja
Priority to KR1020217040550A priority patent/KR20210155810A/ko
Priority to CN202080051868.8A priority patent/CN114127533A/zh
Priority to US17/285,587 priority patent/US11906483B2/en
Publication of WO2020231683A1 publication Critical patent/WO2020231683A1/fr
Priority to US17/237,437 priority patent/US11906482B2/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/20—Investigating strength properties of solid materials by application of mechanical stress by applying steady bending forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • G01N3/06—Special adaptations of indicating or recording means
    • G01N3/068—Special adaptations of indicating or recording means with optical indicating or recording means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014—Type of force applied
    • G01N2203/0023—Bending
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
    • G01N2203/0075—Strain-stress relations or elastic constants
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/026—Specifications of the specimen
    • G01N2203/0262—Shape of the specimen
    • G01N2203/0278—Thin specimens
    • G01N2203/0282—Two dimensional, e.g. tapes, webs, sheets, strips, disks or membranes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/0641—Indicating or recording means; Sensing means using optical, X-ray, ultraviolet, infrared or similar detectors
    • G01N2203/0647—Image analysis

Definitions

  • the present disclosure relates generally to apparatuses for testing glass and/or glass ceramics and methods of testing glass and/or glass ceramics.
  • High-performance display devices such as liquid crystal displays (LCDs) and plasma displays, are commonly used in various electronics, such as cell phones, laptops, electronic tablets, televisions, and computer monitors.
  • LCDs liquid crystal displays
  • plasma displays are commonly used in various electronics, such as cell phones, laptops, electronic tablets, televisions, and computer monitors.
  • Currently marketed display devices can employ one or more high-precision glass sheets, for example, as substrates for electronic circuit components, or as color filters, to name a few applications.
  • the leading technology for making such high-quality glass substrates is the fusion draw process, developed by Corning Incorporated, and described, e.g., in U.S. Patent Nos. 3,338,696 and 3,682,609, which are incorporated herein by reference in their entireties; however, embodiments described herein are applicable to any forming process including slot draw, redraw, float, and the like.
  • a glass sheet is typically cut to size, and then resulting sharp edges of the glass sheet are beveled by grinding and/or polishing.
  • Cutting, edge machining, grinding and other processing steps can introduce flaws, such as chips or cracks, at surfaces and edges of the glass sheet These flaws can serve as fracture sources and thereby reduce the strength of the sheets, particularly if the glass is flexed such that the flaws experience tensile stress.
  • Display devices experience some flexing, thus the existence of these flaws may be of concern.
  • Flexible display devices by their very nature, may produce significant stress in the display substrate(s), either during the manufacturing process or in use.
  • glass substrate- based flexible display devices may have unacceptably high probability of fracture after the glass sheets are made into the final products.
  • Exemplary embodiments lead to a drastic reduction in the amount of time devoted to edge quality control, a dramatic increase in total glass tested versus glass produced, a dramatic increase in the percentage of edge perimeter tested, and a means for simultaneous process feedback for use in pursuit of product improvement.
  • Exemplary embodiments will be described directed to methods for the continuous measurement of the breaking strength of a glass edge by putting the edge under stress, such that stresses away from the edge are significantly less than the breaking strength at their respective locations. Additionally, using exemplary embodiments both sides of an edge can be subject to substantially the same tensile stress during the measurement. Additionally, exemplary embodiments provide a continuous high speed nature which results in at least a 3 Ox increase in processing speed, at least a 3x increase in the number of sample edges tested, and orders of magnitude of the size of the population of glass sheets that are covered by the sample of edges tested. This increase in statistical sampling can thus guarantee less leakage of defects to the customers and is amenable to online configurations.
  • an apparatus for testing edge strength of a sheet of material comprises a plurality of assemblies configured for selectively applying a 3 -point bending load along an edge of the sheet of material in a test region of the apparatus, whereby the plurality of assemblies can establish a loaded condition on the sheet of material in the test region by applying the 3 -point bending load and establish a no-load condition on the sheet of material in the test region by not applying the 3-point bending load.
  • the apparatus also includes a detection mechanism configured for optically measuring strain in the sheet of material in the test region when the sheet of material is in the no-load condition and when the sheet of material is in the loaded condition. The loaded condition is produced by the 3 -point bending load.
  • the apparatus also includes a processor that is configured for determining stress in the sheet of material based on the measured strain.
  • the apparatus can include a plurality of assemblies configured for continuously advancing the sheet of material through a test region of the apparatus along an edge of the sheet.
  • the plurality of assemblies are further configured for selectively applying a 3 -point bending load on the edge of the sheet of material passing through the test region.
  • the apparatus also includes a detection mechanism configured for optically measuring strain on a surface of the sheet passing through the test region, where the strain is produced by the applied load.
  • the apparatus also includes a processor for determining stress in the sheet passing through the test region resulting from the applied load, where the stress is determined based on the measured strain.
  • a method of testing edge strength of a sheet of material along an edge of the sheet comprises: applying a surface pattern of visual markers on a surface of the sheet in a region of interest along the edge of the sheet; obtaining a first optical image of the surface of the sheet in the region of interest without any 3-point bending load applied to the region of interest; applying a 3 -point bending load to the region of interest along the edge of the sheet; obtaining a second optical image of the surface of the sheet in the region of interest while the 3-point bending load is being applied to the region of interest; and determining stress on the surface of the region of interest along the edge of the sheet resulting from the application of the 3-point bending load based on the first optical image and the second optical image.
  • another method of testing edge strength of a sheet of material along an edge of the sheet using a test apparatus that comprises a test region comprises: applying a surface pattern of visual markers on a surface of the sheet in a region of interest along the edge of the sheet; continuously advancing the sheet of material through the test apparatus wherein the edge of the sheet is advanced through the test region while applying a 3 -point bending load to the portion of the sheet passing through the test region; obtaining a first optical image of the surface of the sheet in the region of interest while the edge of the sheet is continuously advancing through the test region but before the region of interest reaches the test region; obtaining a second optical image of the surface of the sheet in the region of interest when the region of interest advances into the test region while the 3-point bending load is being applied; and determining stress on the surface of the region of interest along the edge of the sheet resulting from the application of the 3-point bending load based on the first optical image and the second optical image.
  • FIGS. 1A- ID are schematic illustration of some examples of the hardware configuration in the standard edge strength measurement system (ESMS) for performing the 3-point or 4-point bending test on an edge of the glass sheet for edge strength.
  • ESMS standard edge strength measurement system
  • FIG. IE is a schematic illustration for a 3-point bending test arrangement for testing edge strength of a test sample.
  • FIG 2 is a plot of variation in load-stress at the tension side of a test panel with change in adhesive location between the panel
  • FIG. 3 is a plot of variation of load-stress at the tension side of the test panel with change in roller engagement location
  • FIG. 3 A is a schematic illustration of the basic principle of digital image correlation (DIC) process that is used in the edge strength testing method described herein.
  • DIC digital image correlation
  • FIG. 3B is a stress vs. time plot showing the repeatability study for the DIC at the same location during load cycling.
  • FIG. 3C shows the stress distribution along the top edge during 3 -point bending.
  • FIG. 3D shows the overall load-stress curves of the test samples in the repeatability study for the DIC.
  • FIG. 4 is an isometric view of an embodiment of an ESMS as disclosed herein.
  • FIG. 5 A is a side view of the ESMS of FIG. 4.
  • FIG. 5B is a close-up view of the arcuate members of the apparatus of FIG. 5A that are engaging the sheet being tested.
  • FIG. 6 is a top view of the apparatus shown in FIGS. 4 and 5A.
  • FIG. 7 is a close up view illustration of one arrangement of the assemblies for making the 3 -point contact with an edge of the test sheet to bend the test sheet for testing the edge strength according to an embodiment of the present disclosure.
  • FIG. 8 A is a sample strain field obtained at a load of 6N.
  • FIG. 8B is a chart showing the maximum stress through a test in static mode.
  • FIG. 8C shows a comparison of stress fields generated using a digital image correlation (DIC) apparatus disclosed herein compared with stress field results generated using finite element analysis (FEA).
  • DI digital image correlation
  • FFA finite element analysis
  • FIG. 8D shows a chart with maximum stress versus displacement calculated using the digital image correlation apparatus disclosed herein and using finite element analysis.
  • FIG. 9A is a schematic showing the dynamic mode of an apparatus as disclosed herein.
  • FIG. 9B is a schematic showing a sequence of regions being imaged as a sheet of material advances through the plurality of assemblies without a load.
  • FIG. 9C is a schematic showing a sequence of regions being imaged as a sheet of material advances through the plurality of assemblies with an applied load.
  • FIG. 9D is a schematic illustration showing two ways of using DIC for test sheet stress measurement: measuring the stress on the test sheet’s top surface and measuring the stress on the vertical edge surface.
  • FIG. 9E shows a 3D stress plot on the edge and top surfaces of a glass test sheet.
  • FIG. 10A shows a digital image correlation strain map of an 1 IN load with 60 steps in between
  • FIG 10B shows a strain map from the same test with only one step, which confirms they are identical.
  • FIG. 11 A on the top portion of the figure, shows a first schematic of a sample arrangement for use in calibration of ESMS and, on the bottom portion, shows a top view of the test sheet depicted in the schematic.
  • FIG. 1 IB on the top portion of the figure, shows a second schematic of a sample arrangement for use in calibration of ESMS and, on the bottom portion, shows a top view of the skewed sheet depicted in the schematic.
  • FIG. l lC on the top portion of the figure, shows a third schematic of a tilted sample arrangement for use in calibration of ESMS and, on the bottom portion, shows a top view of the sheet depicted in the schematic.
  • FIG. 1 ID on the top portion of the figure, shows a schematic of a fourth sample arrangement for tilted sample arrangement for use in calibration of ESMS and, on the bottom portion, shows a top view of the skewed sheet depicted in the schematic.
  • FIG. 12 shows a schematic of belt rollers that can be used in embodiments disclosed herein.
  • FIG. 13 shows a schematic of ball rollers that can be used in embodiments disclosed herein.
  • FIG. 14 shows schematic side view and top view illustrations of a configuration for cameras for monitoring both the horizontal top surface of the test sheet along the edge and the vertical edge surface of the test sheet according to another embodiment of the D1C system of the present disclosure.
  • FIG. 15 is a schematic illustration showing the location of the load cell with respect to the arcuate members and the position of the test sheet 204.
  • FIG. 16 is an applied load vs. sample edge position plot showing the improved load control achieved with the aggregate of the improvements to the ESMS disclosed herein.
  • FIG. 17 shows a plot of load vs. time measured on ten sample sheets at a faster speed at which the test sample sheet 204 moves over the rollers with a speed of 10 mm/s.
  • FIG. 18 shows a plot of load vs. time measured on ten sample sheets at a slower speed at which the test sample sheet 204 moved over the rollers with a speed of 1 mm/s.
  • FIG. 19A is an illustration of the ESMS test system according to an embodiment showing a test sheet mounted on a sample stage.
  • FIG. 19B is a detailed close up illustration of the desired roller engagement location along the edge of a test sheet 204 which is at a distance D from the edge E of the bottom roller 218.
  • FIG. 19C is an illustration showing the positioning of the test sheet 204 at the start of the testing procedure with the ESMS so that the leading edge EL of the test sheet rests above the apex of the bottom roller 218.
  • FIG. 20 is an illustration of an example of a test sheet 204 identifying a fly-in zone, measurement length, and a fly-out zone.
  • FIG. 21 is a plot showing an example of the load profile starting from the initial period during the lowering of the upper rollers 220a, 220b, the Fly-in zone, the
  • FIG. 22 is a schematic illustration of an example of a test sheet 204 identifying a new crack position being detected.
  • FIG. 23 A is a schematic illustrating the Phantom Motor technique applied to improve the load control in the ESMS according to an embodiment of the present disclosure.
  • FIG. 23B is a plot of the measured load readings taken without the Phantom Motor technique modification.
  • FIG. 23C is a plot for the measured load readings taken with the Phantom Motor technique.
  • FIG. 24 is a graph illustrating the impact of the roller diameter/polymer thickness on the load-to-stress correlation as determined by finite element analysis.
  • FIG. 25 is a plot of Stress (MPa) vs. Load (N) comparing two groups of panels of two different thicknesses 0.2 mm and 0.3 mm measured by DIC and modeled by FEA.
  • FIG. 26A is a plot of Stress (MPa) vs. Load (N) showing the modeled load-to- stress correlation for panels having different total thicknesses.
  • FIG. 26B is a plot of Normalized change in stress vs. Load (N) showing the normalized change in stress with respect to thickness variations in panels.
  • FIG. 27A is a plot of force over time measured with dynamic ESMS for 0.1, 0.15, 0.2, and 0.5 mm thick glass sheets.
  • FIG. 27B is a plot of displacement over time measured with dynamic ESMS for 0.1, 0.15, 0.2, and 0.5 mm thick glass sheets.
  • FIG. 28 is a schematic illustration of a test panel/sheet showing the distance d from the center of the edge of the test panel/sheet to the test locationoa
  • FIG. 29 is a plot showing the impact of roller engagement on the load-to-stress correlation as determined by FEA and DIC measurements
  • FIG. 30A is a photograph showing an example of an off-apex breakage in a test panel/sheet during an edge strength test.
  • FIG. 30B is a plot of normalized stress vs. distance from the roller apex for an off- apex break in a test panel/sheet.
  • FIG. 31 is a plot of ESMS stress profile.
  • FIG. 32 is a probability vs. stress plot showing the strength distribution of a batch of panels that were analyzed either by the“Simplified method” or“Right” methods.
  • FIG. 33 is a schematic illustration showing the different panel surface nominations
  • FIG. 34 shows a schematic illustration of the propagation of a pre-existing crack on the long edge which interfered with the short edge measurement.
  • FIG. 35 shows the stress profiles on Surface 1 and Surface 3 when the gap between the sealant to glass edge was 0 mm.
  • FIG. 36 shows the stress profiles on Surface 1 and Surface 3 when the distance between the sealant to glass edge is 2 mm.
  • FIG. 37 is a schematic illustration of a machine learning neural network for identifying cracks in the test panels/sheets.
  • FIG ⁇ 38 is a schematic of a panel with its design parameters.
  • FIG. 39 is a schematic illustration of terminal, non-terminal edges of a panel engaged with the rollers in the ESMS of the present disclosure.
  • FIG. 40 is a flowchart illustrating a method according to an embodiment of the present disclosure.
  • FIG. 41 is a flowchart illustrating a method according to another embodiment of the present disclosure. DETAILED DESCRIPTION
  • V4PTB vertical four point bending
  • Testing the sample coupons by V4PTB is a manually intensive process that takes about one day to process the samples from one glass sheet and hence very few glass sheets are tested, e.g., on the order of about three sheets for every 22,000 sheets produced. Further, such methods are unable to evaluate laminate structures or panels. Such shortcomings can result in significant leakage in the form of bad product reaching a customer.
  • FIGS. 1 A-l D are schematic illustration of some examples of the hardware configuration in the existing ESMS system for performing the 3 promt or 4-point bending test on an edge of the glass sheet for edge strength.
  • FIG. 1A and IB are perspective and plan views, respectively, of exemplary configurations that enabled 3 -point bending test on the edge 205 of a glass sheet 204.
  • the roller assemblies 207b and 213b via the three rollers 215 associated with them, one roller on top side 226 (See FIG. 1 E) of the glass sheet 204 and two rollers on the bottom side of the glass sheet 204 provide a 3-point bending test configuration.
  • the roller assemblies 207c and 213c via the three rollers 215 associated with them, two rollers on top side of the glass sheet 204 and one roller on the bottom side of the glass sheet 204 provide a 3-point bending test configuration.
  • the vertical load that bends the glass sheet 204 is applied using the rollers on the topside.
  • the rollers 215 and the glass sheet 204 are positioned so that the rollers 215 catch the edge 205 of the glass sheet 204 between the top and bottom rollers so that the vertical loading force is exerted on the edge 205.
  • FIG. 1 C is a side view of an exemplary configuration that enabled 4-point bending test on the edge 205 of a glass sheet 204.
  • the roller assemblies 207d and 213d via the four rollers 215 associated with them, two rollers on top side of the glass sheet 204 and two rollers on the bottom side of the glass sheet 204 provide a 4-point bending test configuration.
  • the vertical load that bends the glass sheet 204 is applied using the roller assembly 207d on the top side.
  • the ESMS system can be useful for testing glass sheets used in the manufacture of flat panel displays as such glass sheets must meet stringent surface quality requirements in the display area that are usually in the central portions of the glass sheet away from the edges. Contacting the serviceable or“quality” areas of the glass sheet may impart surface defects that make the glass sheet unusable.
  • the arrangement of the rollers 215 in the exemplary configurations shown in FIGS. 1 A-1D preserves the surface quality on both sides of the glass sheet 204.
  • the ESMS system can be utilized to test sheet materials other than the glass sheet 204 shown in the illustrated examples.
  • the ESMS system can be used to test strength of laminate structures (also referred to as panels), of other rigid or semi-rigid materials.
  • Laminate structures or panels can include a plurality of glass sheets laminated with one or more intermediate polymeric layers or can also, in alternative embodiments, include a structure having a thin film transistor glass substrate and color filter glass substrate having one or more films therebetween or adjacent to either or both substrates.
  • the terms“sheet(s)” and“panel(s)” will be used interchangeably. Unless specifically distinguished, whether sheet(s) or panel(s) are being tested by the ESMS system will not fundamentally change the edge strength testing methodology using the ESMS system.
  • FIG. 38 shows a schematic of a panel identifying some design parameters.
  • W and L are the panel’s width and length, respectively. (1) is the protruding length of the terminal edge, (2) is the distance between the sealant and panel edge, (3) is the sealant width, (4) and (5) are the CF, TFT glass thicknesses, respectively.
  • the dimensions and sealant properties of the panels in order to be tested on ESMS are as follows: Small size rectangular panels that have a length (L) and/or width (W) of 600 mm or less can be tested. Larger size panels are also measurable.
  • the protruding length of the terminal edge (1) is longer than the roller engagement, which can range from 0.5 to 2 mm.
  • the distance between the sealant and panel edge (2) is less than 1 mm.
  • the sealant width (3) is equal to or wider than 500 um.
  • the thickness of the sealant is £ 10 um and have a Young’s modulus of 1 Gpa or greater.
  • the interfacial bond strength between the brittle material and the seal should be sufficient so that no de lamination occurs during the edge strength testing.
  • the total thickness of the CF glass thickness (4) + the TFT glass thickness (5) is 3 0.2 mm but £ 0.5 mm.
  • the CF glass thickness (4) and the TFT glass thickness (5) can be equal or different
  • the mechanical stiffness of display layers that are deposited on the TFf surface are negligible.
  • FIG. 39 shows the side view and top view of panels being engaged with the rollers on both non-terminal and terminal side edges.
  • the terminal edge of a panel is where the TFf glass protrudes relative to the CF glass edge.
  • One of the drawbacks of the ESMS system described in US 2018/0073967 A1 referenced above is that the stress measurement during the edge strength testing is made using load cells attached to the topside roller assemblies 207b, 207c that are used to apply the test load to the glass sheet. This is an indirect way of detecting the stress in the edges. A more direct way of measuring the stress experienced by the test subject glass sheet is desired.
  • FIG. 2 is a plot of variation in load-stress at the tension side of a test panel with change in adhesive location between the panel.
  • the measurement apparatuses and methods disclosed herein provide real-time information on stress distributions in the sheet 204 being tested using Direct Image Correlation (DIC) foil-field imaging techniques.
  • DIC Direct Image Correlation
  • the direct measuring techniques disclosed herein are more accurate than the previous techniques and avoid the need to develop new calibration equations and models each time the glass sheet/panel is redesigned or reconfigured.
  • Examples of the uses of the ESMS described herein include, but are not limited to: (a) calibrating currently existing edge strength testers that do not have DIC capability; (b) investigating the failure modes of new glass sheet/panel designs as the test system has the flexibility to change various testing parameters such as roller engagement, sheet/panel angle, roller diameter, loading rate, etc.; and (c) optically making direct strain
  • an apparatus 200 fin- testing the edge strength of a sheet 204 of material is disclosed.
  • the structures of the apparatus 200 described herein is an exemplary embodiment that is configured to optically measure strain in the sheet 204 when the sheet is in a no-load condition and when the sheet 204 is in a loaded condition.
  • the loaded condition being produced by a 3-point bending load.
  • the apparatus 200 can include a plurality of assemblies 206a, 206b configured for selectively applying a 3-point bending load along an edge of the sheet 204 of material in a test region 208. Selectively applying the 3-point bending load means that the plurality of assemblies 206a, 206b are configured to apply or not apply the 3-point bending load as desired and also control the amount of load applied.
  • the apparatus 200 also includes a detection mechanism configured for optically measuring strain in the sheet 204 in the test region 208 when the sheet 204 of material is in a no-load condition and when the sheet 204 of material is in a loaded condition. The strain in the loaded condition is produced by the applied 3 -point bending load.
  • the apparatus 200 also includes a processor 214 (see FIG. 9C) for determining stress in the sheet 204 based on the measured strain.
  • the applied 3- point bending load on the sheet 204 produces a strain on the surface of the sheet 204 because the applied 3-point bending load bends the sheet 204.
  • the plurality of assemblies 206a, 206b (see FIG. 7) comprise two opposing assemblies 206a and 206b, where the first 206a of the two opposing assemblies comprise a single arcuate member 218 for engaging a first side of the sheet 204.
  • the second 206b of the two opposing assemblies comprise two spaced-apart arcuate members 220a, 220b for engaging a second side 230 of the sheet 204 opposite the first side.
  • the two spaced-apart arcuate members 220a, 220b define the test region 208 between the two spaced-apart arcuate members.
  • the arcuate members 218, 220a, and 220b can be rotatably mounted rollers, as shown in FIG. 9A, belt rollers, bearing rollers, or fixed bushings.
  • Fixed bushing (e.g. non- rotating) structures are shown in FIGs. 4 and 5B.
  • the fixed bushings are configured with an arcuate surface formed from a material having a low coefficient of friction (e.g., a fluropolymer resin).
  • the two spaced-apart arcuate members 220a and 220b are fixed bushing structures for engaging the second side 230 of the sheet 204 as shown in FIGs. 4 and 5B.
  • the non-rotating bushing structures are configured to have narrower width than the rotating roller embodiments so that the bushing structures provide wider space between the two arcuate members while the two contact points on the surface of the test sheet 204 are the same distance apart.
  • the detection mechanism comprises a first optic system 222 for determining the strain on the surface of the test sheet 204 in the test region 208.
  • the first optic system 222 utilizes the DIC technique to determine the strain.
  • DIC technique is described in more detail below but essentially, DIC determines the strain by acquiring two images of an interested region of the test sheet 204: first image taken in a no-load condition, and a second image taken with the interested region of the test sheet in a loaded condition, i.e., under a 3 -point bending load in the context of the present disclosure.
  • the surface of the interested region is provided with some visual markers so that when the two images are compared, any displacement of the visual markers in the loaded condition image caused by strain (deformation) can be detected.
  • the sheet 204 can be a brittle material such as glass or glass ceramic.
  • the 3 -point bending load is enough to deform the sheet 204 of material
  • the plurality of assemblies 206a, 206b comprises a first assembly 206a positioned below the sheet 204 comprising a single arcuate member 218 for engaging a first side (the lower side) of the sheet 204 and a second assembly 206b positioned above the sheet 204 comprising two arcuate members 220a, 220b for engaging a second side (the top/upper side) 226 (see FIGs. 11 A, 11 B) of the sheet 204 opposite the first side.
  • the two arcuate members 220a, 220b are separated by a minimum spacing S in order to provide a clear view of the test region 208 for the optic system.
  • the actual dimension of the minimum spacing S will depend on the particular type of cameras and the size of the test region 208 that is determined by the particular arrangement of the arcuate members 220a, 220b, and 218 chosea
  • the arcuate members 218, 220a, and 220b are preferably structures that contacts the sheet 204 while the arcuate members and the sheet are moving relative to each other while imparting low friction at the contact surface.
  • Some examples of such arcuate members are cylindrical rollers, as shown in FIGS. 7, 9A-9C, and 11 A-l ID, and bearing rollers as shown in FIG. 13.
  • the arcuate members 218, 220a, 220b can be bek rollers 240c, 240a, 240b.
  • a belt 240a, 240b, 240c extends around a drive shaft 242a, 242b, 242c and an arcuate tensioner 244a, 244b, 244c.
  • the arcuate tensioner can be a cylindrical roller or a static, arcuate tensioner (such as a polished metal finger with an arcuate portion contacting the belt).
  • the arcuate members 218, 220a, 220b are bearing rollers 246a, 246b, 246c.
  • the bearing rollers 246a, 246b, 246c are formed from a roller ball 248a, 248b, 248c disposed and retained within a socket 250a, 250b, 250c.
  • the single arcuate member 218 is vertically aligned between the two spaced-apart, arcuate members 220a, 220b.
  • “longitudinally” refers to the direction of motion of a sheet 204 passing through the test apparatus 200 (e.g., the machine direction).
  • the optic system 222 comprises a first set of stereo (i.e. a pair) CCD cameras 222a, 222b positioned above the second side 226 of the sheet 204 to inspect the surface of the sheet 204 in the test region 208 between the two spaced-apart arcuate members 220a, 220b.
  • the test region 208 is the region between the arcuate members 220a, 220b, under the two cameras 222a, 222b where the two cameras 222a, 222b are aimed to take digital images to make optical measurements.
  • the test region 208 represents the field of view of the two cameras 222a, 222b.
  • the test region 208 is the region where the three arcuate members 221, 220, and 218 can apply a 3-point bending test load.
  • the test region 208 represents the target area of the test apparatus for applying a 3 -point bend test on a test sample.
  • a test sheet 204 to be tested needs to be brought into the test region 208 for edge strength testing.
  • the test apparatus 200 can be operated in a dynamic mode. In a dynamic mode, the edge strength testing of the sheet 204 is conducted by passing the sheet 204 through a test region 208 of the testing apparatus 200.
  • the testing apparatus 200 can be configured so that the edge strength testing of the sheet 204 is conducted by keeping the sheet 204 stationary and having the testing apparatus traverse over the sheet 204.
  • [00107] can include a plurality of assemblies 206a, 206b configured for continuously advancing the sheet of material through the test region 208 along an edge of the sheet 204.
  • the plurality of assemblies 206a, 206b are further configured for applying a 3 -point bending load on the edge of the sheet of material passing through the test region 208.
  • the apparatus 200 also includes a detection mechanism configured for optically measuring strain on a surface of the sheet passing through the test region 208, where the strain is produced by the applied 3-point bending load.
  • the apparatus 200 also includes a processor 214 for determining the stress in the sheet 204 passing through the test region 208 resulting from the applied. The stress is determined based on the measured strain.
  • the applied load on the test region 208 produces a strain on the surface of the test region 208 because the applied 3 -point bending load bends the sheet 204 in the test region 208.
  • DIC involves point tracking. It is a full-field optical technique for obtaining displacements and thereby strains.
  • the surface of the second side 226 is applied with a surface pattern 230 as visual markers to facilitates the strain measurements in both no-load state and the loaded state.
  • the load imposed on the sheet 204 in the test region 208 causes the surface of the second side 226 of the sheet 204 to deform which, in turn, distorts and displaces the surface pattern 230 on the second side 226 of the sheet 204.
  • the surface pattern 230 can be an array of dots or points applied on the surface being monitored that will serve as visual markers for the purposes of measuring the strain in the sheet 204.
  • the array of dots or points can be in any pattern, regular or random.
  • the image of the surface pattern 230 on the sheet 204 taken in the no-load condition serves as the reference point for determining the displacement of those reference points caused by the distortion of the surface pattern 230 resulting from the subsequent application of the 3 -point bending load.
  • the first set of stereo cameras 222a, 222b in the optic system 222 observes the distortion of the surface pattern 230 and the image data can be used to determine the amount of strain in the sheet 204.
  • the amount of the distortion needs to be quantified. This is achieved by comparing the image bearing the distorted surface pattern 230 on the top surface 226 of the test sheet 204 to a reference/registration image of the second side 226 in a no-load state where the surface pattern 230 is not distorted.
  • an image of the surface pattern 230 in a no-load state is recorded as a reference or a baseline state using the optic system 222.
  • the reference image is used to register the original location of the various points in the surface pattern 230.
  • the new location of the registered points is tracked in the loaded state image. If the top surface 226 is distorted from the applied load stress, many of the registered points on the top surface 226 will have displaced from their original locationoa
  • the processor 214 can determine and quantify the deformation, i.e. the strain.
  • the algorithms for performing such digital image correlation is well known in the art and more detailed discussion is not necessary here.
  • the surface pattern 230 can be printed on the top surface 226 or projected as an image on the top surface 226 or sprayed on as random pattern on the top surface 226 or etched on using chemical treatment on the top surface 226 or pasted on with manufactured thin film having a pattern on the top surface 226. Nanoparticles can be sprayed on the top surface 226 using airbrush.
  • the pattern 230 can be a speckle pattern or a grid pattern.
  • the surface pattern 230 can comprise a coating of a mixture, or a blend of black and white dots to form a speckle pattern.
  • the stereo cameras 222a, 222b and/or 224a, 224b with proper lensing are used to record the image of the surface patter 230 during the test.
  • the coating of the speckle pattern 230 can be made using oil based black and white spray that produce fine mist resulting in speckles with each speckle covering 5-7 pm.
  • the paint layer was ensured to be less than a few microns so that it doesn’t affect the results.
  • a white light LED lamp was used to illuminate the region of interest for optical inspection by the stereo cameras.
  • FIG. 9D identifies the top surface 226 and the edge surface 204e on a test sheet 204.
  • the edge strength measured from both approaches should be the same since the stress is continuous at the edge boundary.
  • FIG. 9E shows a 3D stress plot on the edge and top surfaces of a test sheet
  • the gradients in the image represented by the difference in the darkness of the shading show that the stresses on the top and edge surfaces are continuous.
  • the darkness of the shading in the gradients represent different stress levels but the actual stress values are not important for the purposes of this disclosure.
  • test sheet 204 is coated with visible speckle dot surface pattern 230, that glass sheet is not usable for consumer application even if it survives the edge strength test screening.
  • non-visible speckles that are only visible to specialized optical systems employed by the apparatus (eg., ultraviolet light, fluorescent imaging, infrared light, or another non-visible portion of the electromagnetic spectrum).
  • Exemplary embodiments have been described directed to a method for the continuous measurement of the breaking strength of a glass edge by putting only the edge under stress, such that stresses away from the edge are significantly less than the breaking strength at their respective locations. Additionally, using exemplary embodiments both sides of an edge can be subject to substantially the same tensile stress during the measurement.
  • acoustic energy and/or infrared energy both coherent and incoherent can also be used for the same purpose to induce stress at the edge of a glass sheet.
  • focused ultrasound can be used to induce stress at a glass edge and measurements taken therefrom using the apparatuses and methods disclosed herein.
  • IR irradiation using a laser or other means may also be used to induce stress at a glass edge and exemplary measurements taken therefrom using the apparatuses and methods disclosed herein.
  • exemplary embodiments provide a continuous high speed nature which results in at least a 30x increase in processing speed, at least a 3x increase in the amount of edge tested, and orders of magnitude of sheets processed and tested over conventional methods. This increase in statistical sampling can thus guarantee less leakage to the customer and is amenable to online configurations.
  • E is the Elastic modulus
  • exx is the strain along the bending direction (x)
  • Eyy is the strain along the other in-plane principal axis (y)
  • u is the Poisson’s ratio.
  • the previous practice of stress conversion neglects the biaxiality of the stress state and uses the Hooke’s law for uniaxial stress condition. This provides less information than the DIC technique described herein and oversimplifies the results.
  • test sheets 204 had laminated structures such as display panels. The thickness of the test sheets was about 200 pm. Speckle patterns 230 were made on the vertical edge surface 204e of the test sheet 204. When testing certain types of test sheets 204 such as those having laminated structures, it may be more desirable to conduct the optical monitoring on vertical edge surface 204e rather than the top (horizontal) surface of the test sheet 204.
  • FIG. 14 shows a schematic illustration of an embodiment of the camera configuration for the optic system 222 of the test apparatus 200 enabling DIC that can optically measure the strain along the vertical edge surface 204e during 3-point bending test according to an embodiment.
  • a second set of at least one camera 222c, 222d is provided aimed at the vertical edge surface 204e of the test sheet 204.
  • the at least one camera 222c, 222d is aimed at the vertical edge surface 204e in the test region 208 between the two spaced-apart arcuate members 220a, 220b.
  • the at least one camera 222c, 222d can be used to obtain optical images of the vertical edge surface 204e in both the no-load condition and the loaded conditioa
  • a pair of cameras 222c, 222d are illustrated in FIG. 14 observing the vertical edge surface 204e in the test region 208, when observing the vertical edge surface 204e, a single camera can be utilized because the vertical edge surface 204e is flat even when the 3-point bending load is applied. Because the vertical edge surface 204e is flat, a 3D view using two cameras is not necessary.
  • FIG. 14 also shows a second set of at least one camera 224c, 224d that is aimed at the vertical edge surface 204e but at a location away from the test region 208. Similar to the pair of cameras 224a, 224b, the second set of at least one camera 224c, 224d can be used for obtaining optical image of the vertical edge surface 204e in a no-load condition when the test apparatus 200 is operating in a dynamic mode. Again, although a pair of cameras 224c, 224d are illustrated in FIG. 14, a single camera can be utilized for observing the vertical edge surface 204e.
  • the processor 214 is connected to the cameras 222c, 222d, 224c, and 224 d and the processor 214 can control the cameras as well as receive and process the optical images from the cameras.
  • the inventors developed two ways of making fine speckle patterns. The first one, the inventors used a fine brush with liquid paint to make a layer of paint on the edge surface. Then, a lens tissue was used to make a pattern on the edge surface. The lens tissue has a fine random pattern at microscale, and the area with fiber absorb paint, and the area without fiber leaves the paint on the edge surface. This technique provides good speckle pattern for imaging. Another technique for making fine speckle pattern is using
  • FIG. 3B shows the repeatability study for the DIC at the same location during load cycling. It shows that the repeatability of DIC on the edge is stable. The accuracy of DIC is in ⁇ 10 MPa as we can see at load-free state.
  • FIG. 3C shows the stress distribution along the top edge during 3-point bending. The individual curves are the stress distribution along the top edge at different loads.
  • FIG. 3C shows the stress distribution from loading to the point of the test sheet 204 breaking. From those curves, it can be seen that the defects along the edge affect the stress distribution.
  • FIG. 3D shows the overall load-stress curves of the test samples.
  • edge surface DIC is done at high magnification.
  • the resolution of one pixel is about 0.5 pm
  • the stress is localized at the Apex location.
  • the variation is due to edge defects, accuracy of Apex location, and sample variations such as thickness, intrusion, layer different, sealing stage and others,
  • a conventional acrylic paint can be used to form very thin (few microns) coating of the speckle surface pattern 230 on the glass sheet 204.
  • the modulus of the paint is at least an order less than the glass sheet 204 and its thickness is couple of orders lower than the glass sheet 204, the effect of the patter on the
  • the top surface and edge surface DIC can be performed statically or dynamically.
  • Static DIC measures the load-to-stress correlation at a fixed location along the edge of the test sheet 204.
  • Dynamic DIC measures the load-to-stress correlation along the entire length of the edge of the test sheet 204.
  • Static DIC is easy to perform, but can only measure a single location at a time.
  • Dynamic DIC is more complex to perform, but can measure the entire length of the edge of the test sheet 204.
  • Static DIC works best for samples such as monolithic glass where the correlation doesn’t change with respect to edge location.
  • Dynamic DIC works best for samples such as panels having laminated structure where the correlation may vary.
  • the first set of stereo cameras 222a, 222b are used to obtain both the no-load measurement and the loaded measurement in a stepwise manner.
  • a surface patter 230 of visual markers is provided on the top surface 226 of the test sheet 204.
  • the test sheet 204 is moved in a stepwise manner through the test region 208 of the test apparatus stopping when the particular region of the sheet 204 to be tested is brought into the test region 208 so that the no-load and loaded measurements can be taken.
  • the first optic system 222 includes at least two cameras 222a, 222b in order to optically inspect and detect deformation of the sheet in the no-load measurement and the loaded measurement
  • the no-load measurement and the loaded measurement can be made back to back at each of the four test regions.
  • the no-load measurements for the four Regions 1-4 can be made first, then the sheet 204 can be moved back to the initial position and then the loaded measurements can be made for each Deformation 1, 2, 3, 4 states by moving the sheet 204 through the test region 208.
  • any form of optical measurement requires a clear direct optical view of region of interest on the test sheet 204 in the test region 208 for the measurement
  • U.S. Patent Application Publication No. 2018- 0073967 there was no direct stress measurement and their design did not allow for a clear optical pathway to the region of interest because the rollers blocked the path.
  • the arcuate members 220a, 220b are modified to allow clear optical pathway to the region of interest for the cameras. See FIGS. 4-7, 9A-9C, and 1 lA-11 D. This modification and the resulting improvements are also present for the testing apparatus 200 whether the apparatus is operated in a static DIC mode or a dynamic DIC mode.
  • the key design considerations were:
  • the top rollers (the arcuate members) 220a, 220b were changed from a wheel to a partial section. Specifically, the partial section width was minimized for maximum optical pathway while maintaining the required contact area on the glass sheet 204 of a Ml roller. See FIGS. 5A and 5B.
  • Fine micrometer level adjuster 232 was incorporated for x, y, z axis control to enable precision alignment of glass to rollers/upper partial sections for studying the effects of engagement See FIGS. 5A and 5B.
  • Fine micrometer level adjustment 234 was incorporated for axis control to enable precision alignment of glass to rollers/upper partial sections for studying the effects of skew. See FIGS. 5A and 5B.
  • FIG. 8C An example of the stress field obtained at a load step of 6N along with the history of maximum stress throughout a test is shown in FIG 8C. It is believed that this kind of stress visualization/measurement was never done before. The results were correlated with numerical simulation (e.g., finite element analysis) and a good agreement is seen as shown in FIG. 8C.
  • an example of the method of testing edge strength of a sheet of material along an edge of the sheet 204 of material can be outlined as follows: the method comprises: (a) applying a surface pattern of visual markers 230 on a surface 226 (the second side) of the sheet 204 in a region of interest along the edge of the sheet 204 (see box 510); (b) obtaining a first optical image of the surface of the sheet 204 in the region of interest along the edge of the sheet without any 3 -point bending load applied to the region of interest (see box 520); (c) applying a 3-point bending load to the region of interest along the edge of the sheet (see box 530); (d) obtaining a second optical image of the surface of the region of interest along the edge of the sheet while the 3-point bending load is being applied to the region of interest (see box 540); and (e) determining stress on the surface of the region of interest along the edge of the sheet resulting from the application of the 3
  • the step (e) of determining stress on the surface of the region of interest along the edge of the sheet comprises:
  • the step of measuring strain in the sheet of material in the region of interest in the loaded condition based on the second optical image comprises determining the displacement of the visual markers 230 in the second optical image compared to the visual markers’ location in the first optical image.
  • the step of determining stress on the surface of the region of interest along the edge of the sheet comprises calculating the stress that would be required to produce the measured strain in the sheet of material in the region of interest
  • applying the surface pattern of visual markers comprises printing, coating, spraying, etching, pasting, or projecting an image on the surface of the sheet
  • the first optical image and the second optical image are obtained using an optic system comprising at least one camera 222a, 222b.
  • the apparatus 200 can operate in a dynamic mode where the apparatus 200 can obtain both the no-load measurements and the loaded measurement while the test sheet 204 is continuously moving through the test apparatus 200 without pausing.
  • both the no-load measurements and the loaded measurements are made during a single pass of the test sheet 204 through the test apparatus 200.
  • the optic system 222 can further comprise a second set of stereo cameras 224a, 224b positioned ahead of the test region 208 for obtaining the no-load condition measurement by recording an image of the test sheet 204 without any 3-point bending load applied to it.
  • the second set of stereo cameras 224a, 224b are positioned above the second (top) side 226 of the test sheet 204 and because they are looking at a section of the test sheet 204 ahead of the test region 208 as the test sheet 204 passes by before moving into the test region 208, the second set of cameras 224a, 224b can record the image of the section of the test sheet 204 at no-load condition. This is illustrated by the Deformation 1 case, the left most illustration in FIG. 9C.
  • the second side 226 of the test sheet 204 experiences tension as the sheet passes under the topside arcuate members 220a, 220b and over the bottom arcuate member 218.
  • the arcuate members 218, 220a, 220b are rollers.
  • the method for testing edge strength of a sheet 204 of material along an edge of the sheet using the test apparatus 200 operating in a dynamic mode can be summarized using the flowchart 600 in FIG. 41.
  • the method comprises: (a) applying a surface pattern of visual markers 230 on a surface of the sheet in a region of interest along the edge of the sheet 204 (see box 610); (b) continuously advancing the sheet of material through the test apparatus 200 wherein the edge of the sheet is advanced through the test region while applying a 3-point bending load to the portion of the sheet passing through the test region 208 (see box 620); (c) obtaining a first optical image of the surface of the sheet in the region of interest while the edge of the sheet is continuously advancing through the test region 208 but before the region of interest reaches the test region (see box 630); (d) obtaining a second optical image of the surface of the sheet’s region of interest when the region of interest advances into the test region while the 3 -point bending load is being applied (see box 640); and (
  • the step of determining the stress on the surface of the region of interest along the edge of the sheet 204 comprises: measuring strain in the sheet of material in the region of interest in a no- load condition based on the first optical image; measuring strain in the sheet of material in the region of interest in a loaded condition, wherein the 3 -point bending load is applied, based on the second optical image; and comparing the measured strain in the no-load condition to the measured strain in the loaded condition to determine the strain in the sheet induced by the applied 3-point bending load.
  • the step of measuring strain in the sheet of material in the region of interest in the loaded condition based on the second optical image comprises: determining the displacement of the visual markers 230 in the second optical image compared to the visual markers’ location in the first optical image.
  • the step of determining stress on the surface of the region of interest along the edge of the sheet comprises calculating the stress that would be required to produce the measured strain in the sheet of material in the region of interest.
  • the first optical image and the second optical image are obtained by an optic system comprising at least two cameras 222a, 222b, 224a, 224b.
  • applying the surface pattern 230 of visual markers comprises printing, coating, spraying, etching, pasting, or projecting an image on the surface of the sheet.
  • the stress is determined in at least two dimensions.
  • the two-dimensional stress is displayed as a surface plot
  • FIG. 8 A shows the two-dimensional surface strain on a sheet when loaded by the 3-point contacts. 216 denotes the peak strain location with high stress and 217 denotes a far field location with low stress.
  • FIG. 8B is an exemplary plot showing the applied load vs. maximum stress on the test sheet measured multiple times.
  • FIG. 8C is also a 2-dimensional surface stress field on a sheet when loaded by the 3-point contacts. The left image is measured by DIC and the right image is modeled by FEA.
  • FIG. 8D shows the normalized stress values as a function of vertical distance from the peak stress location to the inward sheet direction (shown as black arrow). The stress increases as a function of applied load.
  • this system apart from being a calibration unit in its static condition, can also be used in a manufacturing environment (or otherwise) with continuous edge testing in a dynamic mode.
  • the direct optical pathway to the surface of the material being tested facilitates the more accurate direct strain measurements relied upon herein.
  • the setup described above can be modified by switching the partial rollers (e.g., arcuate members) with 3 fully functional rollers that can intake the sample continuously feeding into it as shown in FIGS. 9A-9C and 11 A-l ID.
  • the partial rollers e.g., arcuate members
  • 3 fully functional rollers that can intake the sample continuously feeding into it as shown in FIGS. 9A-9C and 11 A-l ID.
  • Such a system will have the rollers in a position such that the incoming glass edge will continuously be subjected to a required bending/load.
  • the spacing between the rollers and their diameters are controlled to provide a minimum spacing S between the two rollers 220a, 220b so that there is a clear optical path for camera to inspect.
  • FIGs. 9B-9C describes the methodology to accomplish real-time stress
  • the edge strength tester needs to pro- inspect the edge (without any load/bending, the sample passes through the rollers) before testing so that preexisting breakages can be detected. If such a breakage is not detected, then the system would malfunction or overestimate the edge strength.
  • the stereo cameras 222a, 222b can take series of pictures along the length of the edge as shown in FIG. 9B. Then, in the second pass when a load is applied on the sample edge, the cameras take another set of images at exact locations on the edge are the first series of images as shown in FIG. 9C by pairing corresponding images from same location and then correlating, one could obtain strain fields and thereby stresses as described previously, i.e. by correlating identically numbered images in FIG. 9B and 9C.
  • an embodiment of the testing apparatus 200 with two sets of stereo cameras 222a, 222b and 224a, 224b can be used to make dynamic measurements in a single pass.
  • An example of such embodiment is shown on the left-most schematic of FIG. 9C.
  • the system includes the first set of stereo cameras 222a, 222b and the second set of stereo cameras 224a, 224b.
  • both sets of stereo cameras are connected to a processor 214 that controls the cameras 222a, 222b, 224a, 224b and also processes the image data from the cameras.
  • the system can also include a display 228 for displaying any of the analytical information on the measured stress in the sheet 204 as well as displaying the image of what the cameras see.
  • FIGS. 10A and 10B show the results obtained from proof testing this concept and confirm that it is possible to obtain accurate results without the intermediate images.
  • the series of 150-200 images taken during a static test at 1 IN load were correlated to obtain the stress distribution map shown in FIG. 10A.
  • FIG 10B shows the stress distribution map obtained by correlating the 1 * image with the 200 th image without any of the intermediate images.
  • the two stress distribution maps are identical, showing that the absence of the intermediate steps does not affect the result.
  • this embodiment describes the dynamic system of edge strength measurement for ultra-thin monolithic and laminate glass samples with real time stress visualization.
  • the test apparatus 200 described herein can be used for performing the method. This is referring to a dynamic DIC method. Dynamic DIC refers to when it obtains strain measurement in real-time while the 3 points“roll” along the edge. Obtaining strain after a no-load measurement is required in such scenarios.
  • An example of the dynamic method of testing edge strength of a sheet 204 of material along an edge of the sheet using the test apparatus 200 that comprises a test region 208 can be outlined as follows.
  • the method comprises: providing a surface pattern 230 of visual markers on a surface 226 of the sheet 204 that includes the edge of the sheet;
  • stress can be determined in a time resolved domain, i.e., the history of stress evolution is obtained. This can be true in either a static mode, where the measurement is taken on a location along the edge of the test sheet 204 while the test sheet 204 is stationary, or in a dynamic mode where the measurement is taken along a length of the edge of the test sheet 204 while the test sheet 204 is continuously fed through the test apparatus 200 while a predetermined load is applied.
  • Suitable laminate structures can include plural glass sheets having one or more intermediate polymeric layers or can also, in alternative embodiments, include a structure having a thin film transistor glass substrate and color filter glass substrate having one or more films there between or adjacent to either or both substrates.
  • a sheet 204 or glass sheet herein, reference can also be made to glass, glass-ceramic, plastic, as well as, laminate structures and other panels.
  • the test apparatus 200 can test sheets of various sizes.
  • the test sheet 204 can have length/width dimensions ranging from about 5 mm / 5 mm, to about 100 mm / 100 mm, to about 600 mm / 600 mm, to about 1000 mm / 1000 mm, to about 2300 mm / 2600 mm, to about 4000 mm / 4000 mm and all subranges there between.
  • Glass sheets in panels or laminate structures may also have length/width dimensions ranging from about 5 mm / 5 mm, to about 100 mm / 100 mm, to about 600 mm / 600 mm, to about 2300 mm / 2600 mm, to about 4000 mm / 4000 mm and all subranges there between Further, adjacent glass sheets in panels or laminate structures may have different length/width dimensions which can result in an overlap of one sheet on the other and on one or more sides of such sheets.
  • Exemplary glass thicknesses for a single glass sheet testing or individual glass sheet contained in a panel or laminate structure can be less than 0.1 mm (e.g., as low as 10 microns) to thicknesses greater than 5 mm, between 0.1 mm to 3 mm, between 0.4 mm to 2 mm, between 0.5 mm to 1 mm, between 0.5 mm to 0.7 mm.
  • the table 202 may include a plurality of driving mechanisms which are configured to move the glass sheet 204 into a predetermined position to commence a measurement cycle or to continuously advancing the glass sheet 204 through the test region 208 for the dynamic mode testing.
  • a predetermined portion of an edge of the glass sheet 204 can be tested.
  • a width of this predetermined portion can range from about 1 mm to about 5 mm, from about 1.5 mm to about 3.5 mm, from about 2 mm to about 3 mm, and all subranges there between. Since the primary purpose of testing the glass sheet 204 is to test the strength of the sheet material along its edge, it is generally desired to test the areas close to the edge as possible. To that end, for the glass sheets having the dimensions mentioned above, engaging the final 2 mm of the surface of the glass sheet 204 along its edge with the arcuate members 220a, 220b, and 218 would generally ensure stress concentration is at the glass sheet edge.
  • This set up is also beneficial in minimizing any chances of catching extraneous particles (such as dust) between the glass sheet 204 and the arcuate members 220a, 220b, and 218 which can introduce unwanted surface cracks.
  • the sheet 204 is a panel or laminate structure measured for edge strength and where adjacent glass sheets in these panels or laminate structures are different (e.g., one or more edges of the structure have an overlapping feature)
  • the predetermined portion is measured with respect to the smaller of the glass sheets in the structure (i.e., the non-overlapping sheet).
  • the arcuate members 220a, 220b, and 218 in each or any of the assemblies 206 can be made of compliant materials to minimize the risk of creating a break in the glass sheet 204 during non-destructive testing (e.g., not evaluating maximum stress).
  • the arcuate members or rollers can be selected to have sufficient compliance while being able to provide a long life to minimize maintenance and downtime as well as sufficient friction to allow the roller to roll freely on the glass surface.
  • Exemplary arcuate member materials can include hardened steel rollers, steel rollers, urethane rollers, polyetheretherketone (PEEK) rollers, Shore 80 hardness urethane rollers, polycarbonate (PC) rollers (e.g., Lexan or the like), high-density polyethylene (HPDE) rollers, Shore 90 hardness urethane rollers, urethane coated rollers, or the like.
  • Exemplary urethane rollers can also be employed to reduce rolling noise which can contaminate any signals used by the system, feedback or otherwise.
  • urethane or urethane coated rollers can be used to accommodate debris in the roller path and to make y-direction stress profiles have no inboard stress concentrations. In embodiments used to measure edge strength of panels and laminate structures, it was discovered that less compliant rollers (e.g., PC, HPDE, etc.) were required to achieve adequate edge strength testing results.
  • Exemplary dimensions for each arcuate member or roller can vary depending on the particular embodiment of the present subject matter.
  • roller dimensions can range from a 5 mm to a 15 mm outside diameter (OD), from a 7 mm to a 12 mm OD, from a 9 mm to a 10 mm OD.
  • an exemplary roller dimension can be about 9 mm OD so that stress can be applied nearly all the way to a comer of a glass sheet which is important as many customer issues occur in this area.
  • Exemplary systems can also traverse a glass edge at speeds ranging from 5 mm/s to 500 mm/s or more, or from 2 mm/s to 400 mm/s or more. Exemplary systems are robust and can be used on glass having thicknesses as small as 0.1 mm to thicknesses as great as 1 mm depending on the durability of the polymer material used for the rollers.
  • a high speed closed loop stress control mechanism can be employed to detect cracks as well as ensure applied stress is within a predetermined value of a target, e.g., 2 MPa of target.
  • a load can be applied to a glass sheet 204 using the single arcuate member 218 whereby a load cell signal can be sent to a high speed controller (not shown) which continuously monitors for cracks.
  • This load cell signal can also be used to control the applied load while traversing die edge at a predetermined speed (e.g., 5 mm/sec to 100 mm/sec or more).
  • edge strength test apparatus 200 is not limited to interrogation of just edge features. It is envisioned that embodiments can interrogate surface features as well for conducting defect screening in manufacturing lines. For example, some features on the surface of the glass sheet, e.g., particle contamination and/or visible types of surface defects such as pits, chips or scratches, can be employed with embodiments of the present subject matter. In such embodiments, however, rather than providing strength distributions, the embodiments would utilize size, shape and/or depth distributions, i.e., a dimensional metric, of such surface defects.
  • Exemplary and non-limiting surface features include surface proximity regions (e.g., approximately 20 mm inboard from the edge) and interface regions (where the surface meets the edge) and any size, shape or depth feature of surface defects. Such dimensional metrics can be used alone or with strength metrics obtained from edge features.
  • the test length may span the entirety of a glass sheet edge or may be conducted on a portion(s) of a glass sheet edge.
  • the test length may span from as little as about 1 mm to 5 mm to as much as about 2600 mm, 3000 mm, 4000 mm or more depending upon the length of the glass edge.
  • FIGS. 4-7B, 9A-9C, and 11 A-l ID show schematics of an edge strength test apparatus 200 using three-point bending method.
  • the test sample glass panel 204 is placed under increasing load until failure and the peak load at the failure point is recorded. This peak load is mapped to a stress based on prior empirically developed calibration curve from strain gaging.
  • This technique provides strains/stresses along two directions (x-axis and y-axis), which is a significant improvement over the current practice of using only strains along the bending direction via strain gauging.
  • FIGS. 11 A-l ID system calibration is completed prior to performing actual tests on glass panel.
  • the image correlation software gets to know the angle and distance at which camera is positioned with respect to the test sample. This will help in translating the movements of dot pattern in terms of image pixels to physical dimensions in the 3D space.
  • This calibration step is described schematically in FIGS. 11 A-l ID.
  • FIG. 11 A shows the relative positions of the cameras (222a, 222b), rollers and the test panel. The top rollers are farther away from the panel as the test have not started yet. Now we switch the test panel with predetermined (known to image correlation software) pattern printed on a flat surface.
  • Camera takes a series of photographs of this pattern with the pattern being swiveled around in 3D space yet within camera’s focal region as depicted in FIG. 1 IB-1 ID.
  • a series of images and appropriate software can be used to develop a calibration file that will be used during the actual test on the panel to obtain strains.
  • the static mode has following design features that helps it to act as a calibration device (or benchmarking device) for studying panel/laminate sheet design along with other parametric studies.
  • rollers can be replaced with partial roller profiles, which increases viewable area, especially near the contact points and enables studying stress distribution in that region without additional stress from rollers.
  • alignment techniques such as alignment pins 236a, 236b, that align various components precisely which is very critical for the test to be accurate.
  • FIG. 15 is a schematic illustration showing the new location of the load cell No load cell drift was observed with the new configuration.
  • the stress on the sheet 204 is a function of the load applied on it
  • the stress measurement accuracy depends on the load measurement accuracy.
  • One factor in improving the accuracy in the non-DIC ESMS testing where the test sample sheet 204 is continuously fed into the test region 208 of the tester is the speed at which the test sheet 204 is moved through the test region 208.
  • the conveyance of the test sheet 204 is achieved by using rollers for the arcuate members 218, 220a, 220b.
  • the material for the roller can affect the friction between the rollers and the test sheet which can affect the ability of the rollers to move the test sheet 204.
  • Compliant rollers shrink and expand as they rotate against the test sheet 204 and can induce variation in the load applied by the bottom roller 218.
  • the ESMS test system 200 has little time to adjust for the load variation.
  • Inventors investigated the inpact of the speed at which the test sheet 204 moved over the rollers vs. load control using a commercially available load frame Instroa The results are shown in the plots in FIGs. 17 and 18.
  • the data was generated with ten (10) specimens.
  • the plot in FIG. 17 shows the measured load over time with a speed of 10 mm/s.
  • the plot in FIG. 18 shows the measured load over time with a speed of 1 mm/s.
  • the load control was significantly improved when the speed was reduced from 10 mm/s to 1 mm/s.
  • the load control also depends on the peed and accuracy in which the ESMS test system’s software can adjust for the load variation. Thus, an optimal peed should be selected taking these factors into consideration.
  • an optimal peed should be selected taking these factors into consideration.
  • the rollers preferably have a polymeric coatings on the rolling surface that comes in contact with the test sheet 204 to aid in moving the test sheet 204. Because the polymers are viscoelastic, the material can shrink and expand during rolling. Therefore, the inventors had expected that thinner polymer coating on the rollers would be better for controlling the load applied on the test sheet 204. However, inventors unexpectedly found that thicker polymer coating provided better load control with less variability in the applied load.
  • the total diameter of the roller (roller bearing + polymer coating) was 9 mm.
  • the thickness of the polymer coating was 1.32 mm.
  • FIG. 24 is a plot of the load-to-stress correlations as a function of roller outer diameter LI /roller inner diameter L2 as determined by FEA. The correlations are invariant up to 400 MPa for wide ranges of LI and L2. From the study, inventors were able to understand that the potential variability in the load-to-stress correlation was minimal for dynamic measurement
  • Improvements were made to the control software for the ESMS system 200 to fully automate the system operation in order to make the testing operation more reliable.
  • the system targets small, ⁇ 200 x 130 x 0.2 mm, test sheets/panels. Test samples as thin as 0.2 mm require a much more accurate load control to accurately measure the stress because even small changes in the load induces relatively large changes in stress. Therefore, improvements needed to be made to the control software by improving the control loop to maintain better load control.
  • the control software allowed the ESMS to perform the following automated procedures.
  • One of the initial steps in the edge strength testing procedure is alignment of the test sheet 204.
  • the desired roller engagement is at the distance D (typically at about 2 mm) from the edge E of the test sheet 204. This roller engagement position is shown in FIG. 19B.
  • Such routines comprise generating a thickness profile of the edge of the test sheet 204 to be tested.
  • the length of the test sheet 204 is moved slowly through a pair of thickness sensors 410a, 410b that measures the thickness of the test sheet 204 and generates a thickness profile of the edge of the test sheet 204 to be tested.
  • the thickness data allows for an accurate post measurement analysis of failure stress if the test sheet 204 cracks.
  • This routine also finds the leading edge EL and trailing edge ET of the test sheet 204 and the sample sheet length so that the actual dimensions can be used during the edge strength test rather than recipe dimensions.
  • the test sheet 204 is placed so the leading edge E L is positioned above the apex of the bottom roller 218 at the start of the edge strength testing procedure.
  • FIG. 19C shows this configuration
  • the ESMS drives the test sheet 204 in the direction indicated by arrow M until the apex of the bottom roller 218 is aligned with the starting offset position.
  • the starting offset position refers to a horizontal edge alignment as shown in FIG. 19C.
  • FIG. 20 is an illustration of an example of test sheet 204 identifying a fly-in zone, measurement length, and a fly-out zone.
  • the ESMS drives top roller assembly 220a, 220b slowly downward towards the top surface of the test sheet 204 until small force is detected which signifies that the top rollers 220a, 220b have made a contact with the test sheet 204.
  • FIG. 21 is a plot showing an example of the load profile starting from the initial period during the lowering of the upper rollers 220a, 220b, the Fly-in zone, the Measurement Length, and the Fly- out zone.
  • the ESMS Under the updated control software, the ESMS carries out the following crack detection procedure. User specifies threshold around target load. If threshold is breached, the ESMS immediately disengages the rollers 218, 220a, 220b and stops the test sheet 204. The position of the lower roller 218 (i.e. the apex of the roller 218) where the test sheet 204 is under the applied stress is defined as a new crack position The edge strength testing is continued if enough space is left along the test sheet 204 edge considering the user defined crack offset.
  • FIG. 22 is a schematic illustration of the test sheet 204 showing the position of the detected crack position.
  • Crack offset refers to the distance the rollers are to be moved away from the detected crack position before the rollers can reengage with the test sheet edge to resume dynamic testing. If the crack offset is too short, the crack would propagate and disturb the measurement. If the crack offset is too large, testable edge real estate can be wasted. According to the modeled magnitude and shape of the stress field, the inventors used a minimum 25 mm distance for the crack offset.
  • the ESMS After reengaging the test sheet 204, the ESMS loops through all of the user defined loading forces as long as there is sufficient length of the edge region of the test sheet remains to be tested. ESMS applies a constant force as it traverses along the edge. When a break occurs, the strength of the test sheet 204 can be anywhere between 0 and the stress corresponding to the applied force. Therefore, to accurately determine the strength of the sheet, one must apply multiple step loads in an incremental fashion to better understand the lower bound of the strength. The user can define these step forces based on the level of measurement accuracy he desires. The system must loop through all of the user defined step loads until a break occurs.
  • FIG. 23 A is a schematic illustrating the Phantom Motor technique.
  • the Delta Tau’s Power PMAC motion controller can be configured in such a way where the output of an individual servo loop can be used as an input to another. This allows the system to join the capabilities of both loops on a single actuator and allows the engineer to take full advantage of controller tuning parameters for a device that was not specifically intended to control motioa In this case, the output of a load cell was integrated into the motion system such that its analog output was pointed to the output of a servo loop inside the controller. This is known as the“inner loop”.
  • the servo loop that actually controls physical motion of the actuator is then fed the inner loops output to command physical motioa
  • the motor tuning parameters provided by the Delta Tau system an optimal balance was achieved that allowed the motion controller to respond to real time deviations from the target load and apply the necessary corrections, making for a stable load application across the sample.
  • FIGS. 23B and 23 C show plots of the measured load reading from the load cell vs. time comparing the load cell readings from a test run.
  • the plot in FIG. 23B is for the measured load readings taken without the Phantom Motor technique modification and the plot in FIG. 23C is for the measured load readings taken with the Phantom Motor technique.
  • the plot in FIG. 23 C show substantially less variations in the load cell readings with the Phantom Motor technique implemented.
  • a method of measuring the average strength of identically manufactured panels that have the same design but manufacturing tolerance will be disclosed. There can be two ways to measure the strength of multiple panels to obtain the average strength of the batch:
  • the first method has the advantage of being more accurate than the second, but can be time consuming since all samples must be measured using the optical strain measurement technique which can have multiple process steps and longer time.
  • the second method involves less processing time since it can use the load directly to estimate the strength, but will have an error bar in the estimate since the same nominal correlation is adopted for panels having a certain manufacturing tolerance. Still, the second method is preferred in practice since less test time has the advantage over the additional accuracy obtained from utilizing the first method. Here we detail more about the second method.
  • the nominal load-to-stress correlation can be obtained by conducting multiple optical strain measurements (i.e., DIC) on multiple panels by using either a static or dynamic DIC approach. A higher number of measurements will provide a more accurate estimate of the nominal correlation. As the number of measurements increases, the error bar will also increase due to the manufacturing tolerance of the panels.
  • DIC optical strain measurements
  • FIG. 25 shows a load vs. stress plot for two different batches of panels having average thicknesses of 0.2 and 0.3 mm measured by DIC and modeled with FEA. While DIC measurement results have a scatter due to the panel manufacturing tolerance, FEA model shows only a single result since the nominal panel design parameters were used for the calculatioa
  • correction factors can be applied to the nominal load-to-stress correlation on each panel based on its measured variability.
  • Thickness For example, if a nominal load-to-stress correlation derived from a panel batch having an average thickness of 0.3 mm is applied to a panel having a thickness of 0.29 mm, the stress could be underestimated. Therefore, a correction factor can be applied based on the measured thickness of 0.29 mm. In this case, the correction factor is a function of the measured panel thickness and the average thickness of the panel batch. The mathematical form of the correction factor can be derived from a sensitivity study conducted by DIC and/or FEA modeling.
  • FIG. 26A shows the modeled load-to-stress correlation for panels having different thicknesses of 0.1, 0.2, 0.21, 0.22, and 0.25 mm
  • FIG. 26B shows the normalized change in stress vs. load (N) for the different thicknesses.
  • correction factors could be applied for other panel design parameter that has a certain manufacturing tolerance.
  • Measurement location - The measurement process may also involve
  • FIGs. 27A and 27B show the force and displacement curves vs. time for 0.1, 0.15, 0.2 and 0.5 mm thick glass sheets as they are tested at a constant load on dynamic ESMS. While the force was maintained constant for all thicknesses, the displacement curves showed significantly different behavior as the rollers approached closer to the comers, as shown by the rising behavior as time progresses. This indicated that the stiffness at the comers became lower as the thickness of glass became thinner, which implied that the load-to- stress correlation had to be corrected for measurement location along the edge. Referring to FIG. 28, the measurement location d along the edge of the panel is measured from the center C of the edge of the panel 204 to the center of the test region 208 marked by“X” in FIG. 28.
  • Roller engagement refers to the engagement length between the roller and the panel edge. While roller engagement is typically set to a nominal value, it may vary depending on the straightness of edge and alignment process.
  • FIG. 29 shows an example of the impact of roller engagement on the load to stress correlation. When the engagement varied between 0.7 and 1.7 mm, it had a 10% impact on the load to stress correlation.
  • FIG. 30A is a photograph of an example of an off-apex break in the test panel and FIG. 30B is a plot of the stress profile with respect to the off-apex break location.
  • the correction factors can be applied to the nominal load-to-stress correlation as following:
  • F is the nominal load to stress correlation
  • C1 ⁇ C4 are correction functions that account for each individual variable, thickness (t), measurement location (x), roller engagement (R) and off-apex break location (L).
  • Error bars - Variabilities in certain panel design parameters or measurement processes that cannot be easily measured due to practical reasons can be accounted for as error bars.
  • error bars the variability of the sealant width, position, or individual glass thicknesses comprising a panel can be accounted for as error bars.
  • measurement process variabilities such as errors from the load cell, operator, etc. can also be accounted for as error bars.
  • the final load-to-stress correlation accounting for both correction factors and error bars are shown below:
  • ESMS1 Traditional ways of predicting the reliability of glass in a specific application include deriving a strength distribution based on strength tests, and then scaling the probability of failure for a given reference size to the entire production size. This approach has been successfully used for many years, however it relies on the strength distribution being referenced to a given size.
  • Traditional means of testing glass strength like 4-point bend and ring on ring, that are performed on glass specimens of adequate thickness have the benefit that the stress field in the tested area is constant. Therefore, if a strength distribution is obtained from this data, the resultant distribution is referenced to the area tested (inside the inner ring for ring on ring tests, and inside the inner knives for four-point bend tests).
  • FIG. 32 shows a
  • Panel failure modes describe the different ways or locations a panel may break when tested on the ESMS. It is generally preferred to have consistent or predictable break locations on a panel in order to classify breaks. However, due to complications in the panel structure and flaw populations, the identification ofbreak locations and understanding the exact failure stress maybe challenging. Here we provide examples of failure modes found in panels and ways to estimate their failure stresses.
  • Edge failures - Edge failure is when the edge on Surface 1 breaks under tension (FIG. 33). Edge failure on surface 1 under tension is the intended failure mode to be obtained from the ESMS test. To obtain this failure mode, however, it is required that the two pieces of glass comprising a panel behaves collectively like a single piece of glass. In the case where the two pieces of glass comprising a panel behaves like two separate pieces of glass, the edge failure may also occur at the edge on Surface 3, which will complicate the identification of the break location.
  • the single-piece-of-glass behavior of a panel can be accomplished by ensuring that the sealant adhering the two pieces of glass is well cured, sufficiently wide and sufficiently close enough to the panel edge being measured.
  • the sealant must not delaminate from the shear stress being applied by the test, the modulus of the sealant should be sufficiently high, typically over 1 GPa, and the sealant must well adhere the area around the vicinity of the edge where a load is being applied.
  • FIG. 35 shows the stress profiles on Surface 1 and Surface 3 when the gap between the sealant to glass edge is 0 mm.
  • the sealant width is about 1 mm and the stiffness is 3 Gpa.
  • the peak stress is at the edge of Surface 1 while the edge stress on Surface 3 is less than half, which implies that breaks will only occur on Surface 1.
  • FIG. 36 shows the stress profiles on Surfaces 1 and 3 when the distance between the sealant to glass edge is increased to 2 mm. As the sealant moves away from the loading area, the peak stresses are now located on both edges of Surfaces 1 and 3. The probability of having a failure on the edge of Surface 3 is now the same as that on Surface 1.
  • Failures from the compressive side surface refer to failures that occur at the edge or surface of Surface 4 due to the small tensile stress being applied by the two outer rollers (FIG. 33). Due to force balance, the tensile stress beneath each outer roller is half of that being applied by the center roller. Despite the smaller stresses on surface 4, breaks may still occur at the edge or surface of Surface 4 if there are large flaws. While it is still generally desired to have breaks only on Surface 1, others may take advantage of this and test flaws on both Surfaces 1 and 4 simultaneously. This potentially eliminates the need for having two sets of rollers to test both A side and B sides.
  • Adjacent cracks - Adjacent cracks are ones that occur when a pre-existing crack extends out to the loading area (FIG. 34). In effect, a pre-existing crack propagates into an adjacent test region and subsequently becomes the origin of failure. This failure mode usually occurs when the distance between test regions are too close. The way to mitigate this failure mode is to ensure that enough distance is provided between adjacent breaks and test locations.
  • Gauge failure modes describe the ways the gauge may fail to detect a break or falsely detect a break on a panel.
  • Missed break detection refers to when the ESMS fails to detect a break on a panel. The inventors found that this usually occurs when the breaking energy from the crack is small relative to the sensitivity of the load cell. In some cases, the crack could still be adhered by the underlying sealant that bonds the two pieces of glass together.
  • False break detection refers to when the ESMS detects a break when no actual break occurred. The inventors found that this usually occurs when the sensitivity of the load sell is too high relative to the noise from the environment
  • ESMS crack detection the panel samples are captured with cameras with different illumination and magnification.
  • the hand-crafted features are difficult to identify to define panel crack from image frames.
  • the captured video samples have most of the image frames as un-cracked glass. There are very limited cracked glass image frames from collected data.
  • This problem is handled as abnormality detection using unsupervised learning.
  • the machine learning model is trained with normal images and find common features. Then, encoder and decoder are used to detect outlier, the outlier images are treated as abnormal images. The crack image would be detected as abnormal image in this case.
  • FIG. 37 illustrates the machine learning model.
  • G and D are adversarial and unsupervised learning using the training data, which is composed of only the target class. Specifically, G learns to reconstruct the positive samples and tries to fool the detector D with feature weighting z and G(z). Whereas, D learns to distinguish original (positive) samples from the reconstructed ones. In this way, D learns merely the concept characterized by the space of all positive samples, and hence it can be used for distinguishing between positive and novelty classes. There is another neural network E which has been trained to mirror the behavior of G which would be able to extract feature weighting from image.
  • G learns to efficiently reconstruct the positive samples, while for negative (or novelty) samples it is unable to reconstruct the input accurately, and hence, for negative samples it acts as a decimator (or informally a distorter).
  • D operates as the actual novelty detector, while G improves the performance of the detector by adequately reconstructing the positive or target samples and decimating (or distorting) any given negative or novelty samples.
  • Embodiments and the functional operations described herein can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them.
  • Embodiments described herein can be implemented as one or more computer program products, Le., one or more modules of computer program instructions encoded on a tangible program carrier for execution by, or to control the operation of, data processing apparatus.
  • the tangible program carrier can be a computer readable medium.
  • the computer readable medium can be a machine-readable storage device, a machine readable storage substrate, a memory device, or a combination of one or more of them.
  • processor or“controller” can encompass all apparatus, devices, and machines for processing data, including by way of embodiment a programmable processor, a computer, or multiple processors or computers.
  • the processor can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them.
  • a computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, or declarative or procedural languages, and it can be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.
  • a computer program does not necessarily correspond to a file in a file system.
  • a program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code).
  • a computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.
  • the processes described herein can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output.
  • the processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit) to name a few.
  • FPGA field programmable gate array
  • ASIC application specific integrated circuit
  • processors suitable for the execution of a computer program include, byway of embodiment, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer.
  • a processor will receive instructions and data from a read only memory or a random access memory or both.
  • the essential elements of a computer are a processor for performing instructions and one or more data memory devices for storing instructions and data.
  • a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks.
  • mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks.
  • a computer need not have such devices.
  • a computer can be embedded in another device, e.g., a mobile telephone, a personal digital assistant (PDA), to name just a few.
  • PDA personal digital assistant
  • Computer readable media suitable for storing computer program instructions and data include all forms data memory including nonvolatile memory, media and memory devices, including by way of embodiment semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks.
  • semiconductor memory devices e.g., EPROM, EEPROM, and flash memory devices
  • magnetic disks e.g., internal hard disks or removable disks
  • magneto optical disks e.g., CD ROM and DVD-ROM disks.
  • the processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.
  • a computer having a display device, e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor, and the like for displaying information to the user and a keyboard and a pointing device, e.g., a mouse or a trackball, or a touch screen by which the user can provide input to the computer.
  • a display device e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor
  • a keyboard and a pointing device e.g., a mouse or a trackball, or a touch screen by which the user can provide input to the computer.
  • Other kinds of devices can be used to provide for interaction with a user as well; for embodiment, input from the user can be received in any form, including acoustic, speech, or tactile input
  • Embodiments described herein can be implemented in a computing system that includes a back end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front end component, e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the subject matter described herein, or any combination of one or more such back end, middleware, or front end components.
  • the components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network.
  • Embodiments of communication networks include a local area network (“LAN”) and a wide area network (“WAN”), e.g., the Interet.
  • the computing system can include clients and servers.
  • a client and server are generally remote from each other and typically interact through a communication network.
  • the relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other
  • Ranges can be expressed herein as from “about” one particular value, and/or to "about” another particular value. When such a range is expressed, examples include from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.
  • substantially is intended to note that a described feature is equal or approximately equal to a value or description. Moreover, “substantially similar” is intended to denote that two values are equal or approximately equal. In some embodiments, “substantially similar” may denote values within about 10% of each other, such as within about 5% of each other, or within about 2% of each other.

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Abstract

Un appareil destiné à l'essai d'une feuille de matériau fragile est divulgué. L'appareil peut comprendre une pluralité d'ensembles configurés pour l'application sélective d'une charge de flexion en trois points sur un bord de la feuille de matériau dans une région d'essai de l'appareil, un mécanisme de détection qui réalise une mesure optique d'une contrainte dans la feuille de matériau dans la région, et un processeur qui détermine la contrainte dans la feuille sur la base de la contrainte mesurée par calcul de la contrainte qui serait requise pour produire la contrainte mesurée dans la feuille de matériau.
PCT/US2020/031553 2019-05-15 2020-05-06 Procédés et appareil de test de résistance de bord WO2020231683A1 (fr)

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JP2021568312A JP2022533625A (ja) 2019-05-15 2020-05-06 縁部強度試験方法及び装置
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CN202080051868.8A CN114127533A (zh) 2019-05-15 2020-05-06 边缘强度测试方法及设备
US17/285,587 US11906483B2 (en) 2019-05-15 2020-05-06 Apparatus and method for testing edge strength of sheet of material having detection mechanism for optically measuring strain in sheet
US17/237,437 US11906482B2 (en) 2019-05-15 2021-04-22 Edge strength testing of free-form glass panel

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