Systems and methods for glass streak improvement by high resolution heating

Abstract

A system and method for repairing streaks in a glass ribbon formed from a glass forming step is disclosed. The system includes a laser generating a fixed laser beam having a wavelength of about 1 μm to about 12 μm and a beam width that is less than or equal to the full width at half maximum of the change in thickness of the glass ribbon across the streak width at the streak location, and optical components that adjust and direct the laser beam at the streak location. The method includes forming a glass ribbon, identifying streaks in the glass ribbon, and directing a laser beam to the streak location. The laser beam heats the glass ribbon at the location of the streak, thereby reducing the viscosity of the glass ribbon and causing glass thinning, reducing the severity of the streak.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority under 35 U.S.C. § 119 to U.S. Provisional Application Serial No. 63 / 282,370, filed November 23, 2021, the contents of which are incorporated herein by reference in their entirety.

[0002] (Technical field) The present specification relates generally to glass forming processes for producing continuous glass ribbons, and more particularly to systems and methods for reducing the severity of streaks on glass ribbons formed by the glass forming processes. [Background technology]

[0003] The melting process is one technique for forming glass ribbons. The melting process produces glass ribbons with relatively few defects and with surfaces that have excellent flatness. As such, the melting process is widely adopted in the manufacture of glass substrates used in the manufacture of displays for electronic devices, and other substrates that require excellent flatness. In the melting process, molten glass is fed into a forming body (e.g., a melt forming vessel), which includes forming surfaces that converge along a bottom edge (e.g., a root) of the forming body. The molten glass flows over the forming surface of the forming body and meets at the root to form a ribbon of flat glass having an initial surface that is drawn from the root of the forming body. The melting process can be a downdraw process or an updraw process. Glass ribbons can also be produced using a slotdraw process or a redraw process.

[0004] During the formation of the glass ribbon, streaks can develop in the glass ribbon, which are narrow regions (e.g., less than 50 millimeters (mm) wide) of the glass ribbon where the thickness of the glass changes abruptly with width change. These abrupt thickness changes in the regions of the streaks can cause distortions of light passing through the glass ribbon, including causing distortions of images displayed on electronic displays made from the finished glass ribbon or sheet. Summary of the Invention [Problem to be solved by the invention]

[0005] Thus, a continuing need exists for systems and methods for repairing streaks in a glass ribbon formed from a glass forming process, such as, but not limited to, a fusion downdraw process, a fusion updraw process, a slotdraw process, a redraw process, or other glass ribbon forming process in which the glass ribbon is under tension. [Means for solving the problem]

[0006] In a first aspect of the present disclosure, a method of repairing streaks during a glass ribbon forming process includes forming a glass ribbon in a glass forming process; maintaining the glass ribbon under tension; and maintaining a rate of change in glass ribbon thickness per unit width of the glass ribbon of about 1 nm. t / mm W and identifying streaks in the glass ribbon at locations along a width of the glass ribbon that are equal to or greater than about 50 mm. The width of the streak is equal to or less than about 50 mm. The method further includes directing a laser beam to the locations of the streaks, the laser beam having a wavelength of about 1 μm to about 12 μm, the laser beam heating the glass ribbon at the locations of the streaks. Heating the glass ribbon at the locations of the streaks reduces the viscosity of the glass ribbon, reducing a thickness of the glass ribbon at the locations of the streaks, a rate of change of thickness of the glass ribbon at the locations of the streaks, or both.

[0007] A second aspect of the present disclosure can include the first aspect, wherein the laser beam includes a linear average power density of about 10 milliwatts per millimeter (mW / mm) to about 10 Watts per millimeter (W / mm).

[0008] A third aspect of the present disclosure can include any of the first or second aspects, wherein a beam width of the laser beam at a point where the laser beam is incident on the glass ribbon is less than or equal to a full width at half maximum of a change in thickness of the glass ribbon across the streak width, and the beam width is 1 / e of the laser beam. 2 It is defined as the width.

[0009] A fourth aspect of the present disclosure can include any one of the first to third aspects, wherein the laser beam has a beam width of about 50 mm or less, the beam width being 1 / e of the laser beam at a point where the laser beam is incident on the glass ribbon. 2 It is defined as the width.

[0010] A fifth aspect of the present disclosure may include any one of the first to fourth aspects, and further includes determining a streak width, a thickness profile, or both, and adjusting one or more of a laser beam power, position, shape, intensity distribution, or combinations thereof based on the streak width, thickness profile, or both.

[0011] A sixth aspect of the present disclosure may include any one of the first to fifth aspects, and further includes determining a thickness profile of the glass ribbon at the streak location, and modifying at least one of a shape or intensity distribution of the laser beam based on the thickness profile of the glass ribbon at the streak location.

[0012] A seventh aspect of the present disclosure can include any one of the first to sixth aspects, wherein the laser beam includes a top-hat intensity distribution or a Gaussian intensity distribution.

[0013] An eighth aspect of the present disclosure may include any one of the first to seventh aspects, and further includes identifying a first streak and a second streak, splitting a laser beam into a first beam and a second beam, directing the first beam to the first streak, and directing the second beam to the second streak.

[0014] A ninth aspect of the present disclosure can include any one of the first to eighth aspects, further comprising positioning the laser beam with a reflected sight laser beam along a beam path of the laser beam, the sight laser beam having a wavelength in a range from about 400 nm to about 700 nm, from about 400 nm to about 550 nm, or from about 500 nm to about 550 nm.

[0015] A tenth aspect of the present disclosure can include any one of the first to ninth aspects, wherein the streak is a protruding streak, and the method includes directing the laser beam to a center of the streak.

[0016] An eleventh aspect of the present disclosure may include any one of the first to tenth aspects, wherein the streak is a concave streak, and the method includes splitting the laser beam into a first beam and a second beam spaced apart from the first beam, and directing the first beam and the second beam proximate an outer edge of the streak.

[0017] A twelfth aspect of the present disclosure can include any one of the first to eleventh aspects, wherein the step of directing the laser beam into streaks comprises: 4 Poise to about 7.6 x 10 7.6 The method includes positioning a laser beam at a location along the streak having a viscosity in the poise range.

[0018] A thirteenth aspect of the present disclosure can include any one of the first to twelfth aspects, wherein identifying the streaks includes illuminating the glass ribbon with a light source and identifying light bands, dark bands, or both caused by refraction of light due to changes in thickness of the glass ribbon at the locations of the streaks, wherein the light bands, dark bands, or both identify the locations of the streaks.

[0019] A fourteenth aspect of the present disclosure can include any one of the first to thirteenth aspects, wherein the glass forming process is a fusion draw process.

[0020] A fifteenth aspect of the present disclosure can include any one of the first to fourteenth aspects, wherein directing the laser beam to the streak location includes directing a laser beam to the glass ribbon, the laser beam having a first power level sufficient to cause a change in thickness of the glass ribbon. Directing the laser beam to the streak location further includes measuring a change in thickness of the glass ribbon in response to the laser beam, the change in thickness in response to the laser beam identifying a location of the laser beam on the glass ribbon. The method further includes adjusting a location of the laser beam to the location of the streak and reducing a power of the laser beam to a second power level sufficient to repair the streak.

[0021] A sixteenth aspect of the present disclosure is directed to a system for repairing streaks in a glass ribbon, the system comprising a laser generating a laser beam having a wavelength of about 1 micrometer to about 12 micrometers and a beam width less than or equal to a full width at half maximum of a change in thickness of the glass ribbon across the streak width at a streak location, the beam width being 1 / e of the laser beam. 2 The width is defined as the width of the glass ribbon and is determined at the point where the laser beam is incident on the glass ribbon. The system further comprises one or more optical components operable to change one or more characteristics of the laser beam. The laser and the one or more optical components are positioned to direct the laser beam to the streak location.

[0022] A seventeenth aspect of the present disclosure may include the sixteenth aspect, further comprising at least one beam splitter operable to split the laser beam into a pass portion and a measurement portion of the laser beam.

[0023] An eighteenth aspect of the present disclosure may include the seventeenth aspect, further including a power detector, wherein the at least one beam splitter is operable to direct a passing portion of the laser beam to the streak location and to direct a measurement portion of the laser beam to the power detector.

[0024] A nineteenth aspect of the present disclosure may include any one of the seventeenth or eighteenth aspects, further comprising a sight laser operable to generate a sight laser beam having a wavelength in a range of about 400 nm to about 700 nm and not passing through the glass ribbon, the beam splitter operable to direct the sight laser beam from the sight laser along a beam path of the laser beam, the sight laser beam indicating a position of the laser beam on the glass ribbon.

[0025] A twentieth aspect of the present disclosure can include the nineteenth aspect, wherein the site laser generates a site laser beam having a wavelength in a range from about 500 nm to about 550 nm.

[0026] A twenty-first aspect of the present disclosure can include any one of the sixteenth to twentieth aspects, wherein the one or more optical components comprises a collimating lens operable to collimate the laser beam.

[0027] A twenty-second aspect of the present disclosure may include any one of the sixteenth to twenty-first aspects, wherein the one or more optical components comprise a diffractive optical component operable to change the shape, intensity distribution, or both of the laser beam.

[0028] A twenty-third aspect of the present disclosure can include any one of the sixteenth to twenty-second aspects, further comprising a fiber optic cable extending from the laser to a location proximate to the glass ribbon, and a fiber optic connector coupled to a proximal end of the fiber optic cable, the fiber optic cable operable to deliver a laser beam from the laser to a location proximate to the glass ribbon.

[0029] A twenty-fourth aspect of the present disclosure can include the twenty-third aspect, wherein the optical fiber cable comprises a hollow core fiber or a polycrystalline fiber.

[0030] A twenty-fifth aspect of the present disclosure may include any one of the sixteenth to twenty-fourth aspects, and further includes an articulated arm laser beam delivery system coupled to the laser, the articulated arm laser beam delivery system including a plurality of moveable joints and a plurality of mirrors operable to direct the laser beam from the laser to the glass ribbon via a sealed beam path having a controllable atmosphere.

[0031] A twenty-sixth aspect of the present disclosure may include any one of the sixteenth to twenty-fifth aspects, and further includes a laser positioning stage coupled to the laser or to an optical fiber connector coupled to an end of an optical fiber cable attached to the laser, the laser positioning stage operable to adjust a position of the laser beam relative to the glass ribbon.

[0032] A twenty-seventh aspect of the present disclosure can include the twenty-sixth aspect, wherein the laser positioning stage includes a plate pivotally coupled to a fixed point proximate the location of the streaks. One or more optical components are coupled to the plate, the plate being rotatable about the pivot point. Rotating the plate about the pivot point positions the heating laser beam relative to the glass ribbon.

[0033] A twenty-eighth aspect of the present disclosure may include any one of the sixteenth to twenty-seventh aspects, further comprising a control system, the control system comprising a processor communicatively coupled to the laser and the power detector, a memory module communicatively coupled to the processor, and machine-readable and machine-executable instructions stored in the memory module. The one or more optical components include a beam splitter operable to split the laser beam into a pass portion and a measurement portion. The power detector is positioned to receive the measurement portion of the laser beam. The machine-readable and machine-executable instructions, when executed by the processor, cause the system to automatically determine a measured power of the laser beam using the power detector, and adjust an output of the laser based on the measured power of the laser beam.

[0034] A twenty-ninth aspect of the present disclosure can include any one of the sixteenth to twenty-eighth aspects, wherein the laser beam is configured to cause the glass to melt at about 10 4 Poise to about 7.6 x 10 7.6 It is placed vertically in a position having a viscosity in the working range of poise.

[0035] A thirtieth aspect of the present disclosure may include any one of the sixteenth to twenty-ninth aspects, wherein the one or more optical components comprises a second beam splitter operable to split the laser beam into at least a first beam and a second beam, and a second focusing optical component operable to direct the second beam to a second location on the glass ribbon.

[0036] A thirty-first aspect of the present disclosure can include the thirtieth aspect, wherein the second beam splitter comprises a prism, a diffractive optical element, an axicon, or a combination thereof.

[0037] A thirty-second aspect of the present disclosure may include any one of the thirtieth or thirty-first aspects, wherein the second location on the glass ribbon includes a streak location of the second streak or a location proximate an outer edge of the recessed streak.

[0038] A thirty-third aspect of the present disclosure is directed to a system for producing a glass ribbon, the system including a fusion downdraw process including a former with two forming surfaces converging at a root. The system further includes a system for repairing streaks in the glass ribbon according to any of the sixteenth to thirtieth aspects. In an embodiment, the system includes a laser operable to generate a laser beam having a wavelength of about 1 micrometer to about 12 micrometers and a beam width less than a full width at half maximum of the change in thickness of the glass ribbon at the location of the streak, the beam width being 1 / e of the laser beam. 2 The width is defined as the width of the glass ribbon and is determined at the point where the laser beam is incident on the glass ribbon. The system further comprises one or more optical components operable to change one or more characteristics of the laser beam. The laser and the one or more optical components are positioned to direct the laser beam to the streak location.

[0039] It should be understood that both the foregoing general description and the following detailed description are intended to describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments described herein, and together with the description, serve to explain the principles and operation of the claimed subject matter. [Brief description of the drawings]

[0040] [Figure 1] 1 is a schematic diagram of a glass forming apparatus according to one or more embodiments shown and described herein. [Diagram 2] 2 is a schematic cross-sectional view of a portion of the glass forming apparatus of FIG. 1 taken along reference line 2-2 of FIG. 1 according to one or more embodiments shown and described herein. [Diagram 3] FIG. 1 is a schematic side view of a glass forming process and a system for repairing streaks in accordance with one or more embodiments shown and described herein. [Figure 4] FIG. 4 is a schematic cross-sectional view of a glass ribbon produced by the glass forming apparatus of FIGS. 1 to 3 and having streaks, in accordance with one or more embodiments shown and described herein. [Diagram 5] 1 is a schematic diagram of a streak detection system according to one or more embodiments shown and described herein. [Figure 6] FIG. 1 is a schematic diagram of a system for repairing streaks according to one or more embodiments shown and described herein. [Figure 7A] FIG. 7 is a schematic diagram of the operation of the system of FIG. 6 to repair streaks comprising protrusions extending outwardly from the glass ribbon, according to one or more embodiments shown and described herein. [Figure 7B] 7B is a schematic diagram of the glass ribbon of FIG. 7A after processing of streaks with a laser beam of the system of FIG. 6 according to one or more embodiments shown and described herein. [Figure 8A] FIG. 1 is a schematic diagram of the operation of the system of the present disclosure for repairing streaks comprising recesses extending into the interior of a glass ribbon, according to one or more embodiments shown and described herein. [Figure 8B] 8B is a schematic diagram of the glass ribbon of FIG. 8A after processing of streaks with a laser beam of the present system, in accordance with one or more embodiments shown and described herein. [Figure 9] FIG. 1 is a schematic diagram of another system for repairing streaks comprising a laser and a fiber optic cable according to one or more embodiments shown and described herein. [Figure 10] FIG. 13 is a schematic diagram of yet another system for repairing streaks comprising optical components for splitting a laser beam into two beams for repairing two streaks or for repairing concave streaks, in accordance with one or more embodiments shown and described herein. [Figure 11] FIG. 2 is a perspective view of a positioning stage for positioning a laser beam relative to a glass ribbon according to one or more embodiments shown and described herein. [Figure 12] FIG. 1 is a perspective view of an articulated arm laser beam delivery system according to one or more embodiments shown and described herein. [Figure 13] 1 is a graph of streak severity (left y-axis) and laser beam power (right y-axis) as a function of time (x-axis) for a system for repairing streaks according to one or more embodiments shown and described herein. [Figure 14] 1 is a graph of thickness (y-axis) as a function of width position (x-axis) on a glass sheet for various combinations of heating laser beam power and position in accordance with one or more embodiments shown and described herein. [Figure 15] FIG. 1 is a schematic diagram of a system for repairing streaks in which a laser beam is directed toward a glass ribbon perpendicularly from the root in accordance with one or more embodiments shown and described herein. [Figure 16] FIG. 1 is a schematic diagram of a system for repairing streaks comprising two heating lasers, one on each side of a compact, according to one or more embodiments shown and described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] The drawings are not to scale and certain features may be exaggerated for illustrative purposes.

[0042] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of systems and methods for repairing streaks in glass ribbons produced from a glass forming process are described in detail below, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals are used throughout the drawings to refer to the same or like parts.

[0043] 4, there is illustrated generally one embodiment of a portion of glass ribbon 12 having streaks 102. Streaks 102 may be narrow regions (e.g., less than 50 mm wide) of glass ribbon 12 that exhibit an abrupt change in thickness t of glass ribbon 12 as a function of the width of glass ribbon 12. As described in further detail herein, the change in thickness of glass ribbon 12 at the location of streaks 102 can act as a lens that changes the direction of light passing through the glass, resulting in distortion of images displayed by electronic displays made from glass ribbon 12.

[0044] 6, one embodiment of a system 200 of the present disclosure for repairing streaks 102 in a glass ribbon 12 is depicted generally. The system 200 includes a heating laser 210 that generates a laser beam 202. The system 200 may include one or more optical components 220 that may be operable to collimate, expand, or focus the laser beam 202. The heating laser 210 and the optical components 220 are positioned to direct the laser beam 202 at the streak 102.

[0045] The system 200 may be used in a method of repairing streaks 102 in a glass ribbon 12. The method may include forming the glass ribbon 12, maintaining the glass ribbon 12 under tension, identifying one or more streaks 102 in the glass ribbon 12 at locations along the width of the glass ribbon 12, and directing a laser beam 202 at the locations of the streaks 102 using the system 200. The laser beam 202 provides localized heating to the glass ribbon 12 or a portion of the glass ribbon 12 at the locations of the streaks 102, which may cause the glass to thin under tension. The thinning of the glass may reduce the thickness of the glass ribbon 12, the rate of change of the thickness of the glass ribbon 12, or both, in the region of the streaks 102, thereby reducing the severity of the streaks. Reducing the severity of the streaks may reduce or eliminate distortion of images displayed on an electronic display made from the glass ribbon 12.

[0046] Various embodiments of systems and methods for repairing streaks in a glass ribbon are further described herein with specific reference to the accompanying drawings.

[0047] Directional terms used in this specification - e.g., up, down, right, left, front, back, top, bottom - are intended to refer only to the depicted drawings and are not intended to imply absolute directions.

[0048] Unless expressly stated otherwise, it is not intended that the methods defined herein be construed as requiring that their steps be performed in a particular order, or as requiring a particular orientation of any apparatus. Thus, where a method claim does not actually recite the order in which its steps are to be followed, or an apparatus claim does not actually recite an order or orientation with respect to individual components, or where the steps are not otherwise specifically recited in the claim or description to be limited to a particular order, or where no particular order or orientation with respect to the components of the apparatus is recited, no order or orientation is intended to be inferred in any respect. This applies to all possible implicit bases for interpretation, including logical considerations regarding the arrangement of steps, the flow of operations, the order of components, or the orientation of components, the plain meaning derived from grammatical construction or punctuation, and the number or type of embodiments described in the specification.

[0049] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a" component includes embodiments having two or more such components unless the context clearly dictates otherwise.

[0050] As used herein, the term "thickness" with respect to a glass ribbon refers to the distance between two opposing points on opposing surfaces of the glass ribbon, the opposing surfaces of the glass ribbon being the surfaces having the greatest width. In the accompanying drawings, thickness refers to the distance in the + / -Y direction of the coordinate axis between two opposing points on opposing surfaces of the glass ribbon.

[0051] As used herein, the term "high resolution" refers to a resolution across the width of the glass ribbon of 50 mm or less, for example, 1 mm to 50 mm.

[0052] As used herein, the terms "up beam" and "down beam" refer to the positional relationship of two or more components to the direction of travel of a laser beam along a beam path. If the laser beam encounters a first component before encountering a second component, the first component is considered to be an up beam of the second component. Similarly, if the laser beam encounters the second component before the first component, the first component is considered to be a down beam of the second component.

[0053] Aspects of the disclosed systems and methods are described herein in the context of a fusion downdraw process using the glass forming apparatus of Figure 1. However, the systems and methods disclosed herein may be equally applied to slot-draw, updraw, or redraw processes with similar results.

[0054] 1, a glass forming apparatus 10 for producing glass articles such as glass ribbon 12 is generally depicted. The glass forming apparatus 10 may generally include a melting vessel 14 that receives batch materials 15 from a storage bin 16. The batch materials 15 may be introduced to the melting vessel 14 by a batch delivery device 17 powered by a motor 18. An optional process controller 20 may be provided to operate the motor 18, and a molten glass level probe 22 may be used to measure the glass melt level in a standpipe 24 and communicate the measured information to the controller 20.

[0055] The glass forming apparatus 10 may also include a fining vessel 28, such as a fining tube, coupled to the melting vessel 14 by a first connecting tube 26. A mixing vessel 32 may be coupled to the fining vessel 28 by a second connecting tube 30. A delivery vessel 36 may be coupled to the mixing vessel 32 by a delivery conduit 34. As further shown, a downcomer 38 may be positioned to deliver the glass melt from the delivery vessel 36 to an inlet end 40 of a forming body 50. In the embodiment shown and described herein, the forming body 50 is a melt forming vessel as described herein above.

[0056] The melting vessel 14 is typically made of a refractory material such as refractory (e.g., ceramic) brick. The glass forming apparatus 10 may further include components that are typically made of an electrically conductive refractory metal, such as platinum or platinum-containing metals such as platinum-rhodium, platinum-iridium, and combinations thereof. Such refractory metals may also include molybdenum, palladium, rhenium, tantalum, titanium, tungsten, ruthenium, osmium, zirconium, and alloys thereof, and / or zirconium dioxide. The platinum-containing components may include one or more of the first connecting tube 26, the reinforcing vessel 28, the second connecting tube 30, the standpipe 24, the mixing vessel 32, the delivery conduit 34, the delivery vessel 36, the downcomer 38, and the inlet end 40.

[0057] 2, the mold 50 generally includes a trough 51, a first molding surface 44, and a second molding surface 45. The trough 51 is located in an upper portion 52 of the mold 50 and includes a first dam 60, a second dam 80, and a base 53 extending between the first dam 60 and the second dam 80. The trough 51 can vary in depth as a function of length along the mold 50. The first molding surface 44 and the second molding surface 45 extend vertically downward from the upper portion 52 of the mold 50 (i.e., in the −Z direction of the coordinate axis depicted in the figure) and converge toward each other, meeting at a lower (bottom) edge, or root 46, of the mold 50. It should thus be understood that first molding surface 44 and second molding surface 45, in an embodiment, form an inverted isosceles triangle (or equilateral triangle) extending from upper portion 52 of molding body 50, with root 46 forming the lowermost apex of the triangle in the downstream direction. Pull surface 47 generally bisects root 46 in the + / -Y direction of the coordinate axes depicted in the figures and extends vertically downward (i.e., in the -Z direction) and in the + / -X direction.

[0058] The compact 50 is typically formed from a refractory ceramic material that is chemically compatible with molten glass and can withstand the high temperatures associated with the melt forming process, although in further embodiments, portions of the compact or the entire compact may be formed from other materials, such as metallic materials. Exemplary ceramic refractory materials from which the compact may be formed include, but are not limited to, zircon (e.g., zirconium silicate), low creep zircon, silicon carbide, xenotime, and / or alumina-based refractory ceramics.

[0059] Referring again to FIG. 1, in operation, batch material 15, particularly a batch material of glass forming material, is fed from a storage bin 16 to the melting vessel 14 using a batch delivery device 17. The batch material 15 is melted into molten glass in the melting vessel 14. The molten glass passes from the melting vessel 14 through a first connecting tube 26 to a fining vessel 28. Decomposition gases that may cause defects in the glass are removed from the molten glass in the fining vessel 28. The molten glass then passes from the fining vessel 28 through a second connecting tube 30 into a mixing vessel 32. The mixing vessel 32 homogenizes the molten glass, for example by stirring, and the homogenized molten glass passes through a delivery conduit 34 to a delivery vessel 36. The delivery vessel 36 discharges the homogenized molten glass through a downcomer 38 and into an inlet end 40 of a former 50, which passes the homogenized molten glass through a trough 51 of the former 50.

[0060] 2, the homogenized molten glass fills the trough 51 of the forming body 50, eventually overflows the trough 51, flows along the length of the trough 51, over the first weir 60 and the second weir 80, and then flows vertically downward (the −Z direction of the coordinate axis of FIG. 2). The homogenized molten glass flows from the upper portion 52 of the forming body 50 onto the first forming surface 44 and the second forming surface 45. In particular, the first half ribbon 62 flows over the first weir 60 onto the first forming surface 44, and the second half ribbon 82 flows over the second weir 80 onto the second forming surface 45. First half ribbon 62 and second half ribbon 82 flowing over first forming surface 44 and second forming surface 45, respectively, meet and melt at root 46 to form a glass ribbon 12 that is drawn downstream along drawing surface 47 by pulling roller 90 positioned vertically below root 46 (i.e., in the -Z direction). Glass ribbon 12 may be further processed downstream of forming body 50, such as by segmenting glass ribbon 12 into discrete glass sheets, rolling glass ribbon 12 itself, and / or applying one or more coatings to glass ribbon 12.

[0061] The tensioning roller 90 may be a driven roller operatively coupled to a drive mechanism. The tensioning roller 90 may be positioned vertically below the root 46 (i.e., in the -Z direction) a sufficient distance to allow the glass ribbon 12 to cool to a temperature at which the viscosity of the glass is large enough that the tensioning roller 90 does not cause deformation of the surface of the glass ribbon 12. The tensioning roller 90 may be operable to maintain the glass ribbon 12 under tension.

[0062] Glass ribbon 12 produced from a fusion draw process, slot draw process, redraw process, or other glass forming process may exhibit one or more streaks. As previously discussed, streaks are physical defects on the glass ribbon 12 that cause distortion of images displayed on electronic displays made from the glass ribbon 12. Streaks are unique defects localized at specific locations along the width of the glass ribbon 12. Streaks are characterized by an abrupt change in the overall thickness of the glass ribbon 12 as a function of width across a narrow region of the glass ribbon 12, e.g., a width region less than 50 millimeters (mm) or less than 40 mm. The abrupt change in thickness of the glass ribbon 12 at the location of the streak can act as a narrow lens that refracts, e.g., focuses, light passing through the glass ribbon 12. Such manipulation of light by streaks can cause distortion of images displayed on electronic displays comprising portions of the glass ribbon 12 having the streaks.

[0063] Streaks can result from a number of different causes, such as, but not limited to, imperfections on the surface of the forming body 50, alignment of cords within the glass ribbon 12, or other causes. For example, in some cases, streaks can result from cords within the glass ribbon 12 aligning in a direction perpendicular to the drawing surface 47 of the glass ribbon 12. As used herein, "cord" refers to a thin layer of glass within the glass ribbon 12, the thin layer of glass having a different glass composition than the glass composition of the entire glass ribbon. Referring now to FIG. 4, thin layers of glass representing cords 100 can be present within the glass ribbon 12 and can be disposed at various angles within the glass ribbon 12. As the cords 100 become more perpendicular to the outer surface of the glass ribbon 12, the cords 100 can cause protrusions or depressions in one or more outer surfaces of the glass ribbon, the protrusions or depressions being narrow in the width direction (i.e., the + / -X direction of the coordinate axis of FIG. 4), e.g., less than 50 mm. At the protrusions or depressions, the glass has a thickness that changes rapidly with width (e.g., greater than 1 nanometer change in thickness per millimeter (mm) of width). This abrupt change in thickness across the narrow width of the glass ribbon 12 is called a streak 102. Although FIG. 4 shows streaks 102 protruding outwardly from both surfaces of the glass ribbon 12, streaks 102 can result when only one side of the glass ribbon 12 includes protrusions or depressions that result in an abrupt change in thickness with width. If the viscosity of the glass of the cord 100 is greater than the viscosity of the overall glass composition of the glass ribbon 12, the cord 100 can result in streaks 102 that include protrusions that protrude outwardly from one or both of the outer surfaces of the glass ribbon 12. If the viscosity of the glass of the cord 100 is less than the viscosity of the overall glass composition of the glass ribbon 12, the cord 100 can result in streaks 102 that are depressions that are recessed inwardly relative to one or both outer surfaces of the glass ribbon 12.

[0064] 1-3, in other embodiments, the streaks 102 may also be caused by defects on the forming body 50, such as defects on the first forming surface 44, the second forming surface 45, the first weir 60, the second weir 80, or a combination thereof. During glass production in a fusion downdraw process, such as processing with the glass forming apparatus 10 of FIGS. 1-3, potential surface defects on the forming body 50 may result in very narrow but sharp thickness variations in the first half ribbon 62 or the second half ribbon 82. The sharp thickness variations in the first half ribbon 62, the second half ribbon 82, or both, may be translatable into the glass ribbon 12 as the first half ribbon 62 and the second half ribbon 82 are melted at the root 46. Temperature and flow non-uniformities in the first half ribbon 62, the second half ribbon 82, the glass ribbon 12, or a combination thereof, may further exacerbate these variations. These thickness features (ie, streaks 102) are typically oriented along the pull direction (ie, in the + / -Z direction of the coordinate axes of FIG. 3).

[0065] In many cases, the slope of the thickness change as a function of width in the streak 102 is small enough that the thickness variation of the glass ribbon 12 falls within specifications under stringent inspection conditions. However, if the slope of the thickness change as a function of width in the streak 102 exceeds a threshold, the glass in the streak 102 may act like a cylindrical lens and produce dark and light bands during inspection with a light source. Analogous to an optical lens, the light bands are formed by localized increases in glass thickness (protrusions) in the streak 102. The localized thickening of the glass is typically on the order of a few hundred nanometers (nm) of thickness change over a distance 10 mm to 20 mm wide across the glass ribbon 12.

[0066] The streaks 102 may be identified by shining light from a light source onto the glass ribbon 12 and identifying light and dark areas on a screen caused by a lensing effect due to surface protrusions or surface depressions of the streaks 102. With reference to FIG. 5 , streaks in the glass ribbon 12 may be identified by a streak inspection system 108. The streak inspection system 108 may include an inspection light source 110 and an inspection screen 112. The inspection light source 110 may be positioned to direct light 114 onto a first surface of the glass ribbon 12. The inspection light source 110 may be a xenon light source. The inspection screens 112 may be positioned on both sides of the glass ribbon 12 opposite the inspection light source 110 such that the light 114 passing through the glass ribbon 12 is incident on the inspection screens 112. At the location of the streak 102 on the glass ribbon 12 , the abrupt change in glass thickness acts as a narrow lens that produces light and dark bands on the inspection screen 112 .

[0067] 5, identifying one or more streaks 102 in the glass ribbon 12 may include illuminating the glass ribbon 12 with light 114 from an inspection light source 110. The light 114 passes through the glass ribbon 12 and impinges on an inspection screen 112. The change in glass thickness in the region of the streak 102 acts as a lens to refract the light passing through the region of the streak 102, forming light bands 116 and dark bands 118 on the inspection screen 112. Identifying the streak 102 further includes identifying light bands 116, dark bands 118, or both, on the inspection screen 112 caused by the refraction of the light 114 due to the change in thickness of the glass ribbon 12 at the location of the streak 102. The light bands 116, dark bands 118, or both, identify the location of the streak 102. The dark areas correspond to areas of thinner glass and the light areas correspond to areas of thicker glass.

[0068] The light bands are caused by streaks 102 protruding from the glass ribbon 12 such that the thickness increases at the location of the streak 102 relative to the remainder of the glass ribbon 12. As shown in FIG. 5, when a streak 102 includes a protrusion where the glass thickens, the increase in glass thickness acts as a convex focusing lens that focuses light toward one or more focal points 115, resulting in a light band 116. The area of ​​the glass ribbon 12 outside the area of ​​the streak 102 produces a darker exposure of light on the inspection screen 112 compared to the streak 102 including the protrusion where the glass thickness increases.

[0069] The dark bands are caused by streaks 102 recessed into the glass ribbon 12 such that the thickness is reduced at the location of the streak 102 compared to portions of the glass ribbon 12 outside the area of ​​the streak 102. When a streak 102 comprises a depression where the glass is thinner, the reduced thickness of the glass acts as a concave diverging lens that spreads light away from the focal position of the lens or upstream of the lens, resulting in a dark band 116 on the inspection screen 112. Areas of the glass ribbon 12 outside the area of ​​the streak 102 can cause a brighter exposure of light on the inspection screen 112 compared to the streak 102 with a depression where the glass thickness is smaller.

[0070] Each streak 102 may be a discrete location along the width of the glass ribbon 12 and may extend longitudinally (i.e., in the −Z direction of the coordinate axis in FIG. 3 ) along the glass ribbon 12. At the locations of the streaks 102, the thickness t of the glass ribbon 12 may change (e.g., increase or decrease) by a few hundred nanometers across a width of the glass ribbon 12 that is less than about 50 mm, such as less than about 40 mm. At the locations of the streaks 102, the rate of change of the thickness t of the glass ribbon 12 as a function of the width W of the glass ribbon 12 may be sufficient to focus or converge light passing through the glass, producing light and dark bands on the inspection screen 112. At the locations of the streaks 102, the rate of change of the thickness t of the glass ribbon 12 as a function of the width W of the glass ribbon 12 may be sufficient to focus or converge light passing through the glass, producing light and dark bands on the inspection screen 112. t / mm W For example, at the location of the streak 102, the rate of change of the thickness t of the glass ribbon 12 as a function of the width W of the glass ribbon 12 may be about 3 nm or more. t / mm W More than 4 nm t / mm W or more, about 5nm t / mm W or more, about 10nm t / mm W or more, about 20nm t / mm W or more, or even about 30 nm t / mm W or more. The severity of the streaks 102 refers to the magnitude of the rate of change of the thickness t of the glass ribbon 12 as a function of the width of the glass ribbon 12. Generally, increasing severity of the streaks 102 corresponds to an increasing difference between the maximum thickness (protruding streaks) or minimum thickness (recessed streaks) of the glass ribbon 12 in the region of the streak 102 and the average thickness t of the glass ribbon 12 averaged across the width W of the glass ribbon 12.

[0071] 4 , the streak 102 has a streak width Ws, which is defined herein as the full width at half maximum of the Gaussian distribution of the change in the glass thickness t at the location of the streak 102. The full width at half maximum of the Gaussian distribution of the change in the thickness t of the glass ribbon 12 refers to the distance between two width positions along the streak width Ws at which the change in the thickness t of the glass ribbon 12 is equal to half the maximum value of the change in the thickness t of the glass ribbon 12 in the region of the streak 102. Note that the amount of change in the thickness t of the glass ribbon 12 refers to the difference between the actual thickness t of the glass ribbon 12 and the average thickness averaged over the entire width of the glass ribbon 12.

[0072] Each of the streaks 102 can have a streak width Ws that is about 50 mm or less, about 40 mm or less, about 30 mm or less, about 20 mm or less, or even about 10 mm or less. Each of the streaks 102 can have a streak width greater than zero, such as about 0.5 mm or more, about 1 mm or more, about 5 mm or more, or about 10 mm or more. In embodiments, each streak 102 can have a width of greater than 0 to about 50 mm, such as from about 0.5 mm to about 50 mm, from about 0.5 mm to about 40 mm, from about 0.5 mm to about 30 mm, from about 0.5 mm to about 20 mm, from about 0.5 mm to about 10 mm, from about 1 mm to about 50 mm, from about 1 mm to about 40 mm, from about 1 mm to about 30 mm, from about 1 mm to about 20 mm, from about 1 mm to about 10 mm, from about 5 mm to about 50 mm, from about 5 mm to about 40 mm, from about 5 mm to about 30 mm, from about 5 mm to about 20 mm, from about 10 mm to about 50 mm, from about 10 mm to about 40 mm, from about 10 mm to about 30 mm, or from about 10 mm to about 20 mm. The width of the streaks 102 is measured parallel to the width W of the glass ribbon 12 and lies generally in the + / -X direction of the coordinate axis of Figures 1-5. The streaks 102 may extend continuously longitudinally (ie, in the + / -Z direction of the coordinate axes in Figures 1-3) along the entire length of the glass ribbon 12.

[0073] As previously discussed, streaks in the glass ribbon 12 can cause products produced from the glass ribbon 12, such as, but not limited to, screens for electronic devices, to exhibit distortions in displayed images. The change in glass thickness at the locations of the streaks 102 can cause light refraction at these locations, resulting in distortions in images displayed on screens comprising the glass. Thus, streaks in the glass ribbon 12 can result in quality issues and / or increased waste. Thus, there is a continuing need for systems and methods for repairing streaks in glass ribbons produced from a fusion draw process, such as by reducing the severity of the streaks.

[0074] The local thickening (protrusion) of the glass ribbon with streaks occurs when the viscosity of the glass is in the range of use (10 4 From 7.6×10 7.6 The streaks 102 may be mitigated by locally heating the glass ribbon 12, first half ribbon 62, or second half ribbon 82 while the glass is in tension (poise). Localized heating of the glass ribbon 12, first half ribbon 62, and / or second half ribbon 82 reduces the local glass viscosity when the glass is under tension (e.g., tension rollers, gravity forces, etc.) and thinning is achieved. Conventional resistive heaters used for localized heating of the glass ribbon typically heat large areas of glass (e.g., greater than 100 mm wide) and are not effective at producing controlled localized heating in the area of ​​the streaks 102. This inability to provide targeted localized heating may result in further anomalies in the glass ribbon rather than repairing the streaks.

[0075] The present application is directed to a system and method for repairing streaks in a draw process, such as a fusion downdraw process, an updraw process, a slotdraw process, or a redraw process, by applying high-resolution heating with well-controlled power to the glass near the root 46 of the forming body 50 to smooth out the thickness change in the glass ribbon 12 associated with the streak 102. The high-resolution heating of the glass at the location of the streak reduces the viscosity and reduces the local thickness of the glass (the thickness in the immediately adjacent regions is relatively higher due to mass conservation). This technique works by reducing the thickness and / or reducing the gradient of the thickness change in the glass ribbon 12 as a function of width through localized high-resolution heating. The systems and methods of the present disclosure include a heating laser and optical components configured to modify the laser beam and direct the laser beam to the location of the streak. The laser beam provides high-resolution heating (e.g., heating less than 50 mm wide) with well-controlled power. The directional and spatially well-defined nature of the laser makes the heating laser very effective at locally heating the glass.

[0076] The systems and methods of the present application can reduce or eliminate the severity of streaks in the glass ribbon, which can reduce or eliminate distortion of light passing through articles made from the glass ribbon, such as distortion of images displayed on electronic displays made from the glass ribbon. Reducing distortion of light passing through the glass ribbon can in turn reduce quality issues and reduce waste resulting from the glass forming process. The systems and methods of the present disclosure can provide non-contact direct heating of the streak area without changing the temperature of the surrounding glass or damaging the glass forming equipment. The systems and methods of the present disclosure can reduce the severity of streaks without introducing heat or changing the viscosity of the glass beyond the area of ​​the streaks. The systems of the present disclosure are simple in construction, cost-effective, and contain few moving parts, making the system reliable and easy to maintain. The components of the systems of the present disclosure are compact and lightweight, and can be mounted in many locations on the glass forming equipment. The optical system has a small footprint and can be installed in existing muffle design fusion draw and slot draw equipment without significant modifications. Additionally, the system can be hot installed into an existing muffle without stopping the glass forming process while the glass ribbon 12 is being produced.

[0077] 6, one embodiment of a system 200 for repairing streaks in a glass ribbon 12 produced by a glass forming apparatus 10, including but not limited to a fusion downdraw process, a fusion updraw process, a slotdraw process, or a redraw process, is illustrated generally. The system 200 includes a heating laser 210 that generates a laser beam 202 and one or more optical components 220 configured to change one or more characteristics of the laser beam 202, direct the laser beam 202 to the location of the streak 102, or both. The optical components 220 may collimate, expand, or focus the laser beam 202. In an embodiment, the optical components 220 may include a collimating lens operable to convert the laser beam 202 into a collimated laser beam. The heating laser 210 and optical components 220 may be positionable to direct the laser beam 202 at the glass ribbon 12 or a second portion of the glass ribbon 12 (e.g., the first half ribbon 62, the second half ribbon 82, or both) at the location of the streak 102 ( FIG. 3 ). The system 200 may be operable to direct the laser beam 202 at the glass ribbon 12 or a portion thereof at the location of the streak 102 to provide high-resolution heating of the glass ribbon 12 or a portion thereof at the location of the streak 102. High-resolution heating refers to targeted heating of the glass ribbon 12, the first half ribbon 62, the second half ribbon 82, or a combination thereof over a width region (e.g., in the + / −X direction) of about 50 mm or less, about 40 mm or less, about 30 mm or less, or even about 20 mm or less. High-resolution heating of the glass ribbon 12, first half ribbon 62, or second half ribbon 82 at the location of the streak 102 can locally reduce the viscosity of the glass at the streak, which can at least partially ameliorate the streak (e.g., reduce the severity of the streak by reducing the rate of change of thickness of the glass ribbon 12 at the location of the streak).

[0078] The heating laser 210 is a device capable of generating a laser beam 202. The laser beam 202 can be a single round laser beam or a single elliptical shaped laser beam. The laser beam 202 generated by the heating laser 210 can be a fixed laser beam, meaning that the laser beam 202 propagates along a fixed beam path, which can be determined by the position of the optical components placed on the heating laser 210 and down the beam from the heating laser 210.

[0079] The laser beam 202 may have a wavelength in a wavelength range where the laser beam 202 is absorbed by the glass to heat the glass of the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82, and does not pass through the glass to impinge on the glass forming apparatus 10. Since silicate-based glass has a strong absorption for light having a wavelength of about 4 micrometers (μm) or greater, many different laser sources may be used as the heating laser 210 to generate the laser beam 202 to heat the glass ribbon 12 or half ribbon at the location of the streak 102. The heating laser 210 may be operable to generate the laser beam 202 having a wavelength in the infrared wavelength range. The heating laser 210 may be operable to generate the laser beam 202 having a wavelength of about 1 μm or greater, about 2 μm or greater, about 3 μm or greater, about 4 μm or greater, or even about 8 μm or greater. The heating laser 210 may be operable to generate the laser beam 202 having a wavelength of about 12 μm or less, or even about 10 μm or less. The heating laser 210 may be operable to generate a laser beam 202 having a wavelength of about 1 μm to about 12 μm, about 1 μm to about 10 μm, about 2 μm to about 12 μm, about 2 μm to about 10 μm, about 3 μm to about 12 μm, about 3 μm to about 10 μm, about 4 μm to about 12 μm, about 4 μm to about 10 μm, about 8 μm to about 12 μm, or about 8 μm to about 10 μm.

[0080] The heating laser 210 may be a CO laser, a CO2 laser, a quantum cascade laser (QCL), or other type of suitable laser. In particular, the heating laser 210 may include, but is not limited to, one or more CO2 lasers operating at a wavelength of 5.6 μm; a CO2 laser operating at a wavelength between 9 μm and 11.2 μm, such as 9.3 μm, 9.6 μm, 10.6 μm, or 11.2 μm; or a low-power quantum cascade laser (QCL) that can emit across the mid-to-far infrared (FIR) spectrum (3 to 12 microns). In an embodiment, the heating laser 210 may be a QCL having an emission wavelength of about 3 μm to about 12 μm, or even about 8 μm to about 12 μm, taking into account atmospheric transmission and glass absorption characteristics. The heating laser 210 may be operable to generate a laser beam 202 of a continuous laser or a pulsed laser. A continuous laser generally has a down-side peak power and gradually increases the glass surface temperature, whereas a pulsed laser generally has a high peak power and increases the glass surface temperature more in a short time compared to a continuous laser. The laser beam may be collimated or uncollimated. In an embodiment, the laser beam 202 generated by the heating laser 210 may be a collimated laser beam. In an embodiment, the laser beam 202 may be collimated using a collimating lens placed down-beam from the heating laser 210, as discussed further herein.

[0081] The heating laser 210 has sufficient power to heat the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82 at the location of the streak 102. The required power depends on the glass absorption at the wavelength of the laser beam 202 and can depend on whether the laser beam 202 is directed at the glass ribbon 12 or at the first half ribbon 62 or the second half ribbon 82 that remains in contact with the forming body 50 or other component of the glass manufacturing apparatus. The power of the laser beam 202 can therefore be characterized by a linear average power density. The linear average power density PS of the laser beam 202 refers to the range of absorbed laser power P for streak removal. The linear average power density PS can be calculated according to the following Equation 1 (Equation 1):

[0082]

number

[0083] The laser beam 202 generated by the heating laser 210 can have a linear average power density sufficient to heat the glass ribbon 12 at the location of the streak 102 to repair the streak 102. In an embodiment, the laser beam 202 can have a linear average power density of about 10 milliwatts per millimeter (mW / mm) to about 10 watts per millimeter (W / mm).

[0084] The heating laser 210 can have an absolute linear average power of about 0.001 W / mm to about 10 kW / mm, depending on the wavelength of the laser beam 202. If the power or linear average power density of the laser beam 202 is too low, the energy of the laser beam 202 may be insufficient to heat the glass enough to repair the streak 102. If the power or linear average power density of the laser beam 202 is too high, the laser beam 202 may overheat the streak 102 and / or heat an area of ​​the glass ribbon 12, first half ribbon 62, or second half ribbon 82 that is larger than the area of ​​the streak 102, causing additional physical defects in the glass. The power of the heating laser 210 may be adjusted to adjust the amount of heating of the glass by the laser beam 202. The heating laser 210 may be communicatively coupled to the control system 300 via a wired or wireless communication path. Communication between heating laser 210 and control system 300 can enable control of heating laser 210 and its output power based on one or more measured parameters of system 200, glass ribbon 12, or both.

[0085] Heating laser 210 generates a laser beam 202 having a beam width sufficient to heat the glass of glass ribbon 12, first half ribbon 62, or second half ribbon 82 at the location of streaks 102 without overheating areas of glass ribbon 12, first half ribbon 62, or second half ribbon 82 beyond the area of ​​streaks 102. The beam width of laser beam 202 is determined by the location along the beam path where laser beam 202 is incident on the surface of the glass, the 1 / e 2 It refers to the width of the laser beam 202. 2 The width is the width where the light intensity of the laser beam 202 is 1 / e of the maximum intensity in the intensity distribution of the laser beam 202. 2(0.135) times the distance between two points of the beam. In an embodiment, the laser beam 202 generated by the heating laser 210 can have a beam width within about 50% of the streak width Ws, for example, within about 25% or even within about 10% of the beam width Ws. In other words, the laser beam 202 may have a beam width such that the absolute value of the difference between the beam width and the streak width Ws is less than about 50% of the streak width Ws, for example, less than about 25% or even less than about 10%. In an embodiment, the laser beam 202 may have a beam width of about 50 mm or less. The laser beam 202 may have a beam width of about 40 mm or less, about 30 mm or less, about 20 mm or less, or even about 10 mm or less. The laser beam 202 can have a beam width greater than zero, such as about 1 mm or more, or about 5 mm or more. In embodiments, the laser beam 202 can have a beam width of greater than zero to about 50 mm, such as from about 0.1 mm to about 50 mm, from about 0.1 mm to about 40 mm, from about 0.1 mm to about 30 mm, from about 0.1 mm to about 20 mm, from about 0.1 mm to about 10 mm, from about 0.5 mm to about 50 mm, from about 0.5 mm to about 40 mm, from about 0.5 mm to about 30 mm, from about 0.5 mm to about 20 mm, from about 0.5 mm to about 10 mm, from about 1 mm to about 50 mm, from about 1 mm to about 40 mm, from about 1 mm to about 30 mm, from about 1 mm to about 20 mm, from about 5 mm to about 50 mm, from about 5 mm to about 40 mm, from about 5 mm to about 30 mm, or from about 5 mm to about 20 mm. The beam width of laser beam 202 can be modified by including optical components that focus (converge) or defocus (diverge) laser beam 202 .

[0086] The laser beam 202 can be shaped to further reduce glass thickness variations at the location of the streak 102. The beam shape of the laser beam 202 refers to the cross-sectional shape of the laser beam 202 at the location on the beam path where the laser beam 202 is incident on the surface of the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82. The laser beam 202 can have a beam shape that is generally circular in cross section. In an embodiment, the laser beam 202 can have a beam shape that is elliptical in cross section. In addition to the beam shape, the laser beam 202 can have an intensity distribution that can be tailored to further reduce glass thickness variations. The intensity distribution of the laser beam 202 refers to the intensity of the light of the laser beam 202 as a function of position in the cross section of the beam shape of the laser beam 202. In an embodiment, the laser beam 202 can have an intensity distribution that resembles a Gaussian distribution. In an embodiment, the laser beam 202 may have a top-hat intensity distribution in which the light intensity of the laser beam 202 is generally constant throughout the beam shape, such that a two-dimensional graph of intensity as a function of radius from the center of the laser beam 202 resembles a top-hat shape, e.g., a step function. The beam shape and intensity distribution of the laser beam 202 may be modified based on the thickness profile of the glass ribbon 12 along the streak width Ws of the streak 102. Modifying the beam shape and intensity distribution of the laser beam may be achieved, for example, using diffractive optical components.

[0087] Referring again to FIG. 6 , the system 200 for repairing streaks can include an optical component 220 configured to modify one or more characteristics of the laser beam 202 or modify a beam path of the laser beam 202. The optical component 220 can include various lenses, mirrors, beam splitters, prisms, filters, or other optical components operable to modify a characteristic or beam path of the laser beam 202. The optical component 220 can include a collimating lens that can be configured to convert the laser beam 202 from the heating laser 210 into a collimated laser beam. In an embodiment, the collimating lens can be a ZnSe collimating lens. The collimating lens can be positioned downbeam relative to the heating laser 210, such as between the heating laser 210 and the glass ribbon 12. The optical component 220 can further include one or more focusing lenses, diverging lenses, and / or mirrors (not shown) for focusing, expanding, and / or directing the laser beam 202 to the location of the streak 102, respectively.

[0088] The system 200 for repairing streaks 102 may further comprise one or more beam splitters 230. The term "beam splitter" refers to an optical component that splits a single laser beam into two or more separate beam paths (e.g., one or more stationary beams). The beam splitter 230 may be a prism, one or more diffractive optical components, an axicon, or other device configured to split the laser beam 202 into at least two separate beams. Referring again to FIG. 6, the beam splitter 230 may be operable to split the laser beam 202 into a pass portion 232 of the laser beam 202 and a measurement portion 234 of the laser beam 202. In an embodiment, the beam splitter 230 may be positioned down beam relative to a collimating lens such that after the laser beam 202 is collimated, the beam splitter 230 splits the laser beam 202 into the pass portion 232 and the measurement portion 234. System 200 may further include one or more other focusing lenses, diverging lenses, shaping lenses, mirrors, beam splitters, filters, prisms, diffractive optical components, axicons, etc. to modify the characteristics of laser beam 202 or to change the beam path of laser beam 202.

[0089] The heating laser 210 may be mounted in a fixture (not shown) that is attached to the glass forming apparatus 10, such as a fusion draw apparatus embodying a fusion draw process, or a slot draw apparatus embodying a slot draw process, or other glass forming apparatus. In an embodiment, the heating laser 210 and the optical components 220 may be mounted in a muffle (not shown) of the glass forming apparatus 10. The muffle may be an insulating shroud that encloses some or all of the glass forming apparatus 10, such as the fusion draw process, particularly the forming body 50 and the glass ribbon 12 produced therefrom. The fixture may be operable to position the heating laser 210, the optical components 220, and the beam splitter 230 vertically (e.g., in the + / -Z direction of the coordinate axes of FIGS. 1-6 ) and / or horizontally (e.g., in the + / -X and / or + / -Y directions of the coordinate axes of FIGS. 1-6 ). The heating laser 210 and optical components 220 can be positioned in the width direction (e.g., in the + / -X direction) such that the laser beam 202 is incident on the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82 at or near the location of the streak 102.

[0090] Referring again to FIG. 6, the heating laser 210, the optical components 220, and the beam splitter 230 are made of glass having a thickness of about 100 nm. 4 Poise to about 7.6 x 10 7.6A laser beam 202 can be positioned vertically to be directed at the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82 at a vertical location (i.e., a location in the + / -Z direction of the coordinate axes of FIG. 6) having a viscosity in the working range of poise. In this viscosity range of the glass, heating by the laser beam 202 can be effective to heat the glass and reduce the viscosity of the glass to a point where the glass can thin or relax under tension to repair the streaks 102. As shown in FIG. 6, in an embodiment, the glass forming process can be a melt downdraw process, and the heating laser 210, the optical components 220, and the beam splitter 230 direct the laser beam 202 to a location vertically above the root 46 of the forming body 50 (i.e., in the +Z direction of the coordinate axes of FIG. 15 relative to the root 46) before the first half ribbon 62 and the second half ribbon 82 are melted to form the glass ribbon 12. Although laser beam 202 is shown in FIG. 6 as being directed at first half ribbon 62, depending on the suspected source of streaks 102, laser beam 202 may be directed at first half ribbon 62, second half ribbon 82, or both.

[0091] 15 , in some embodiments, the glass forming process may be a fusion downdraw process and a heating laser 210, optical components 220, and beam splitter 230 may be vertically positioned to direct a laser beam 202 to the glass ribbon 12 at a location vertically below the root 46 of the forming body 50 (i.e., in the −Z direction of the coordinate axes of FIG. 15 relative to the root 46). Now referring to FIG. 16 , in an embodiment, the glass forming process may be a fusion downdraw process and a system 200 may include one heating laser 210, optical components 220, and beam splitter 230 positioned to direct a laser beam 202 to a streak location on the first half ribbon 62 above the root 46, and another heating laser 210′, optical components 220′, and beam splitter 230′ positioned to direct another laser beam 202′ to a streak location on the second half ribbon 82 above the root 46.

[0092] Referring again to FIG. 6, in an embodiment, the system 200 may further include at least one power detector 240. The power detector 240 may be operable to measure the power of the laser beam 202 and output a signal indicative of the power of the laser beam 202. The power detector 240 may be any device capable of absorbing a laser beam and generating a power signal indicative of the power of the laser beam being measured. The power signal may be digital or analog and may propagate via a wired or wireless communication method or medium. The at least one beam splitter 230 is operable to direct the measurement portion 234 of the laser beam 202 to the power detector 240. In an embodiment, the power detector 240 may be positioned to receive the measurement portion 234 of the laser beam from the beam splitter 230. The power detector 240 may be communicatively coupled to the control system 300 via a wired or wireless communication path. The power signal generated by the power detector 240 may be communicated to the control system 300. In an embodiment, the power signal generated by the power detector 240 may be used in feedback control of the output power of the heating laser 210 .

[0093] Referring again to FIG. 6, in an embodiment, the system 200 may further include a sight laser 250. As used herein, the term "sight laser" refers to a low-power laser that generates a sight laser beam that is human-visible and can be oriented along the same beam path as the laser beam 202 for the purpose of providing a visual indication of the location of the laser beam. The sight laser 250 may be operable to generate a sight laser beam 252 having a low power and a wavelength in the visible spectrum, such as a wavelength of 380 nm to 700 nm. The laser beam 202 may have a wavelength in the infrared range and may not be visible to the human eye. This may make it difficult to determine where the laser beam 202 is incident on the glass ribbon 12. The sight laser beam 252 may be used to confirm the location where the laser beam 202 is incident on the glass ribbon 12 and / or on the forming body 50 (e.g., on the first forming surface 44 or the second forming surface 45 of the forming body 50). The sight laser beam 252 can be directed along the same beam path as the laser beam 202 such that the beam path of the sight laser beam 252 is collinear with the beam path of the laser beam 202. In an embodiment, the sight laser beam 252 can be directed by one or more optical components to be coaxial and / or collinear with the laser beam 202.

[0094] The sight laser beam 252 can have a wavelength that is within the visible spectrum. The sight laser 250 can be a laser that can generate a sight laser beam 252 having a wavelength in the range of about 400 nm to about 700 nm. In an embodiment, the sight laser beam 252 can have a wavelength less than about 550 nm, such as about 400 nm to about 550 nm. If the wavelength is greater than about 550 nm, the sight laser beam 252 can be less observable relative to the light emitted from the molten glass and the forming body 50. In an embodiment, the sight laser 250 can be a low-power green laser that generates a sight laser beam 252 having a wavelength of about 500 nm to about 550 nm.

[0095] The system 200 may further include a sight laser optical component (not shown) positioned to direct the sight laser beam 252 along the same beam path as the laser beam 202. In an embodiment, the sight laser optical component may include a beam splitter 230. In an embodiment, the beam splitter 230 may be operable to reflect the sight laser beam 252 along a beam path of the laser beam 202, such as the beam path of the passed portion 232 of the laser beam 202.

[0096] Referring again now to Figures 3-6, the operation of the system 200 for repairing the streak 102 will be described in further detail. With reference to Figure 3, the glass forming apparatus 10 may be operated to form a glass ribbon 12 through a fusion draw process. During the glass forming process, the glass ribbon 12 may be maintained under tension using tension rollers 90. Maintaining the glass ribbon 12 under tension during the repair of the streak 102 may create tension in the glass that may thin the glass when heated with a laser beam 202. With reference to Figure 5, the one or more streaks 102 characteristic of the glass ribbon 12 may be identified by the streak inspection system 108. The system 200 may then be operated to direct the laser beam 202, or any portion thereof (e.g., the passed portion 232 of the laser beam 202), to the location of the streak 102. The laser beam 202 may pass through one or more optical components 220, such as, but not limited to, a collimating lens, a beam splitter 230, or other optical components, which may change the characteristics and / or beam path of the laser beam 202.

[0097] 7A and 7B, the processing of the streak 102 with protrusions, where the glass thickness increases at the streak 102, will now be described. As shown in FIG. 7A, the laser beam 202 is directed at the thickest portion of the streak 102. The laser beam 202, or a portion thereof, incident on the streak 102 heats the glass ribbon 12, or a portion thereof, at the location of the streak 102. The targeted high-resolution (e.g., less than 50 mm wide) heating of the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82 at the location of the streak 102 by the laser beam 202, or any portion thereof, reduces the viscosity of the glass, which causes the glass to thin under tension. Now referring to FIG. 7B, the thinning of the glass may reduce the thickness of the glass ribbon 12 at the location of the streak 102, the rate of change of the thickness of the glass ribbon 12 at the location of the streak 102, or both. As shown in Figure 7B, the rate of change of thickness across the width of the streak 102 is reduced as compared to the streak 102 before treatment (Figure 7A). Thus, by directing the laser beam 202 or any portion thereof at the features of the streak 102, adjusting the laser power, and maintaining the glass ribbon 12 under tension, the streak 102 can be eliminated or significantly reduced.

[0098] 8A and 8B, the treatment of streaks 102 with a recess, in which the glass thickness is reduced at the streak 102, will be described. For a recessed type streak, directing the laser beam 202 at the center of the streak 102 as shown in FIG. 7A will cause more glass thinning at the center of the streak 102 and increase the severity of the recessed type streak 102. Alternatively, for a recessed streak, the laser beam 202 is directed at one or both edges of the streak 102, or at the region of the glass ribbon 12, first half ribbon 62, or second half ribbon 82 immediately beyond the streak 102. By directing the laser beam 202 at one or more locations proximate the outer edges of the streak 102, the glass ribbon 12 can be thinned at the edges of the streak 102. This edge thinning causes the streaks 102 to become wider (i.e., the streak width Ws becomes larger), distributing the thickness change over a greater distance and reducing the slope of the thickness change of the glass ribbon 12 in the region of the streaks 102.

[0099] 8A, the system 200 can include a second beam splitter 270 operable to split the laser beam 202 into a first beam 272 and a second beam 274. Further description of the system 200 having the second beam splitter 270 is provided in relation to FIG. 10. As shown in FIG. 8A, the second beam splitter 270 can be sized and configured to separate the laser beam 202 such that the first beam 272 and the second beam 274 are separated by a distance D. The distance D is the center-to-center distance between the first beam 272 and the second beam 274. The distance D is sufficient such that the absolute value of the difference between the distance D and the full width at half maximum of the streak 102 is less than about 100%, about 75% or less, about 50% or less, about 40% or less, about 30% or less, about 20% or less, about 10% or less, or even about 5% or less of the full width at half maximum of the streak 102. The distance D can be about 50 mm or less, or about 40 mm or less, for the treatment of the concave streaks 102. The distance D between the first beam 272 and the second beam 274 and the positioning of the first beam 272 and the second beam 274 relative to the concave streaks 102 can be determined by the geometric profile of the glass ribbon 12 at the location of the concave streaks 102. The first beam 272 and the second beam 274 can be oriented at the outer region of the concave streaks 102 or slightly beyond the streaks 102. The first beam 272 and the second beam 274 can cause targeted high resolution heating (e.g., less than 50 mm wide) of the glass ribbon 12 proximate the outer edges of the concave streaks 102. This targeted heating can reduce the viscosity of the glass proximate the outer edges of the concave streaks 102, causing thinning of the glass at the outer edges of the streaks 102. Glass thinning can cause localized thinning of the glass ribbon 12 at the edges of the recessed streaks, which can increase the streak width Ws, thereby distributing the total change in glass thickness over a larger width of the glass ribbon 12. Thus, the change in thickness as a function of width is reduced, reducing the severity of the streaks 102.

[0100] Conservation of material may cause a portion of the glass to displace or move toward the center of the streak, resulting in a localized thickening of the glass at the center of the concave-type streak 102, further reducing the rate of change of glass thickness in the region of the concave-type streak 102. Referring now to FIG. 8B, the glass ribbon 12 is depicted generally after treatment of the concave-type streak 102 with the first beam 272 and the second beam 274. As shown in FIG. 8B, treatment with the first beam 272 and the second beam 274 at the outer edges of the concave-type streak 102 may reduce the rate of change of thickness as a function of width, thereby reducing the severity of the concave-type streak 102. Although shown and described in terms of splitting the laser beam 202 into two separate beams, in embodiments, the severity of the concave-type streak 102 may be reduced by directing the laser beam 202 at a single location proximate one of the edges of the streak 102. In some cases, heating the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82 with the laser beam 202 proximate only one edge may be sufficient to widen the streaks 102 and reduce the variation in thickness as a function of width across the location of the streaks 102.

[0101] The laser beam 202, or any portion thereof, is maintained in contact with the features of the streak 102 for the continuous production of the glass ribbon 12. Additionally, operation of the system 200 may include positioning the laser beam 202, or any portion thereof, with a reflected site laser beam 252 along a beam path of the laser beam 202. In an embodiment, the beam splitter 230 may be operable to direct the site laser beam 252 along the beam path of the laser beam 202, or the portion thereof, and the site laser 252 is operable to indicate the location of the laser beam 202, or the portion thereof, on the glass ribbon 12.

[0102] The system 200 is initialized upon identifying the streaks 102 in the glass ribbon 12. Setting up the system 200 may include directing a laser beam 202 in the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82 at a location within at least the general area of ​​the streaks 102. The laser beam 202 may initially have a first power level sufficient to cause a change in thickness of the glass ribbon 12. In an embodiment, the first power level of the laser beam 202 may be about 0.5 W or greater. The location at which the laser beam 202 is incident on the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82 may be identified by measuring the change in thickness of the glass ribbon 12 in response to the laser beam 202. At the location at which the laser beam 202 is incident on the glass, the laser beam 202 heats the glass, which causes the thickness profile of the glass ribbon 12 to change at the location of the laser beam 202. Thus, the change in thickness of the glass ribbon 12 can provide an indication of the location where the laser beam 102 is contacting the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82. Once the location of the laser beam 202 is identified, the position of the heating laser 210 and / or the optical component 220 can then be adjusted to place the laser beam 202 at the location of the streak 102. The power of the laser beam 202 can be reduced to a second power level that is less than the first power level. The second power level of the laser beam 202 can be sufficient to repair the streak 102. The position and power of the heating laser 210 can be adjusted to fine-tune the laser beam 202 based on the severity and thickness profile of the streak 102. One or more of the power, position, beam width, beam shape, beam intensity distribution, or combinations thereof of the laser beam 202 can be adjusted depending on the width, severity, thickness profile, and location of the streak 102.

[0103] As previously discussed, the beam shape, intensity distribution, or both of the laser beam 202 may be altered to tailor the heating provided by the laser beam 202 depending on the width, severity, shape, and location of the streak 102. The system 200 may further comprise a diffractive optical component or other optical component operable to alter the beam shape, intensity distribution, or both of the laser beam 202. Operation of the system 200 may further include determining one or more of the width, severity, and / or shape (thickness profile) of the glass ribbon 12 at the location of the streak 102 and altering the beam shape, intensity distribution, or both of the laser beam 202 based on the width, severity, and / or shape (thickness profile) of the glass ribbon 12 at the location of the streak 102. In an embodiment, the laser beam 202 may have a top hat intensity distribution or a Gaussian intensity distribution. As used herein, a "top hat" intensity distribution refers to an intensity distribution in which the light intensity is approximately constant across the cross-sectional area of ​​the laser beam, e.g., an intensity distribution in which the light intensity is within 10% of the average light intensity across the cross-sectional area of ​​the laser beam. For a Gaussian distribution, the light intensity is greatest at the center of the laser beam and decreases away from the center of the laser beam.

[0104] In an embodiment, the system 200 can include a flexible laser beam delivery system capable of delivering the laser beam 202 from the heating laser 210 to a fixture coupled to the glass forming apparatus 10. The flexible laser beam delivery system can be a fiber optic cable system or an articulated arm laser beam delivery system. The flexible laser beam delivery system can allow the heating laser 210 to be located remotely from the glass forming apparatus 10. This may allow the system 200 to be used to deliver the laser beam 202 to locations where it may be difficult to place the heating laser 210 near the glass ribbon 12, first half ribbon 62, or second half ribbon 82 due to space constraints.

[0105] 9, in an embodiment, a system 200 can include a heating laser 210 mounted remotely from the glass forming apparatus 10 and a fiber optic cable 260 configured to deliver a laser beam 202 from the heating laser 210 to a location proximate to the glass forming apparatus 10 and / or the glass ribbon 12. Mounting the heating laser 210 remotely from the glass forming apparatus 10 means mounting the heating laser 210 out of line of sight from the glass ribbon 12 or at a distance away from the glass forming apparatus 10 from the glass ribbon 12 that is large enough that the heating laser 210 cannot be effectively directed at the glass ribbon 12 or half ribbon using optical components open to atmosphere without frequent disturbance of the beam path. The fiber optic cable 260 can be operatively coupled to the heating laser 210 and can extend from the heating laser 210 to a location proximate to the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82. The fiber optic cable 260 may be a hollow core fiber optic cable or a polycrystalline fiber optic cable.

[0106] The system 200 may further include a fiber optic connector 262 that may be coupled to an end of the fiber optic cable 260 opposite the heating laser 210. The fiber optic connector 262 may be configured to transition the laser beam 202 from the fiber optic cable 260 to air. The fiber optic connector 262 may be positioned to direct the laser beam 202 to the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82. The fiber optic connector 262 may be positionable relative to the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82 in a vertical direction (e.g., in a + / -Z direction of the coordinate axes of FIG. 9 ) and a horizontal direction (e.g., in a + / -X direction and / or a + / -Y direction of the coordinate axes of FIG. 9 ). In an embodiment, the fiber optic connector 262 may be coupled to a fixture (not shown). The fixture may be operable to position the fiber optic connector 262, the optical components 220, and the beam splitter 230 vertically (e.g., in the + / -Z direction of the coordinate axes of FIG. 9 ) and / or horizontally (e.g., in the + / -X and / or + / -Y directions of the coordinate axes of FIG. 9 ). The fiber optic connector 260, the optical components 220, and the beam splitter 230 may be positioned across the width (e.g., in the + / -X direction) such that the laser beam 202 is incident on the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82 at or near the location of the streak 102. The fiber optic connector 262, the optical components 220, and the beam splitter 230 may be positioned across the width (e.g., in the + / -X direction) such that the laser beam 202 is incident on the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82 at or near the location of the streak 102. 4 Poise to 7.6 x 10 7.6 Laser beam 202 can be vertically positioned to direct glass ribbon 12, first half ribbon 62, or second half ribbon 82 at a vertical location (i.e., a location along the + / -Z direction of the coordinate axes in FIG. 9 ) that has a viscosity in the working range of poise. In this viscosity range of the glass, heating with laser beam 202 can be effective to heat the glass and reduce the viscosity of the glass to a point where the glass can thin or relax under tension to repair streaks 102.

[0107] 9 , where the system 200 includes a fiber optic cable 260 and a fiber optic connector 262, the heating laser 210 may generate a laser beam 202 and introduce the laser beam 202 into an end of the fiber optic cable 260. The laser beam 202 may propagate through the fiber optic cable 260 from the heating laser 210 to the fiber optic connector 262. The fiber optic connector 262 may transition the laser beam 202 from the fiber optic cable 260 to the atmosphere. The fiber optic connector 262 may further direct the laser beam 202 to the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82, or the optical component 220 and the beam splitter 230. The laser beam 202 may pass through the optical component 220 operable to modify one or more characteristics of the laser beam 202 or the beam path of the laser beam. At least a second portion of laser beam 202 can then be directed at glass ribbon 12, first half ribbon 62, or second half ribbon 82 such that laser beam 202 is incident on the glass at the location of streak 102. As previously discussed, laser beam 202 can heat the glass at the location of streak 102, causing streak 102 to reduce.

[0108] Referring now to FIG. 10 , in some circumstances, the glass ribbon 12 may develop multiple streaks 102 at multiple locations along the width of the glass ribbon 12. FIG. 10 shows a first streak 102A and a second streak 102B, which may be spaced apart from one another along the width of the glass ribbon 12. Although two streaks are shown in FIG. 10 , it is understood that the glass ribbon 12 may develop more than one streak 102. The glass ribbon 12 may form 1, 2, 3, 4, 5, 6, or more than six streaks. In circumstances where the glass ribbon 12 has two or more streaks 102, the system 200 may be configured to split the laser beam 202 into two or more fixed laser beams and direct each of the two or more fixed laser beams toward one of the streaks 102, such as the first streak 102A, the second streak 102B, or another streak. Each of the laser beams may heat the glass in the streak that it is oriented toward, which may reduce the streaks. In this manner, the system 200 may be configured to simultaneously repair multiple streaks 102 in the glass ribbon 102.

[0109] Referring again to FIG. 10, the system 200 may include at least one second beam splitter 270. The second beam splitter 270 may be positioned down beam with respect to the beam splitter 230. The second beam splitter 270 may be operable to split the laser beam 202, or the passing portion 232 of the laser beam 202 from the beam splitter 230, into multiple laser beams, such as 2, 3, 4, 5, 6, or more than 6 fixed laser beams. The second beam splitter 270 may include one or more beam splitters. In an embodiment, the second beam splitter 270 may be operable to split the laser beam 202, or the passing portion 232, into at least a first beam 272 and a second beam 274. The second beam splitter 270 may include one or more of a prism, a diffractive optical element, an axicon, and combinations thereof.

[0110] System 200 may further include one or more optical components configured to direct first beam 272 and second beam 274 to first streak 102A and second streak 102B, respectively. In an embodiment, the optical components of system 200 may include at least one second focusing lens 280, which may be operable to focus first beam 272, second beam 274, or both, to the locations of the multiple streaks 102A, 102B.

[0111] 11, as previously described, the system 200 can include a fixture 290 to which the heating laser 210 or fiber optic connector 262 and one or more optical components can be coupled. The fixture 290 can be a positioning stage 292 configured to change at least a horizontal position (e.g., in the + / -X and / or + / -Y directions of the coordinate axes of FIG. 11) of the laser beam 102 relative to the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82. The fixture 290 can be coupled to a muffle 92 that can surround at least a portion of the glass forming apparatus 10. The muffle 92 can include one or more ports 94 that allow access to the interior of the muffle 92 and the glass ribbon 12 contained therein. The fixture 290 can be attached to the muffle 92 proximate one of the ports 94 to allow the laser beam 202 to pass through the port 94 to the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82.

[0112] Because the port 94 of the muffle 92 is generally in a fixed location, the fixture 290 may be a positioning stage 292 that is rotatable to change the beam path of the laser beam 202, such as by changing the angle of the laser beam 202, or a portion thereof, relative to the port 94. The rotational ability of the positioning stage 292 may allow the laser beam 202 to cover a significantly larger portion of the width (i.e., the + / -X direction of the coordinate axes in FIG. 11) of the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82, depending on where the streak 102 is located on the glass ribbon 12. The positioning stage 292 may include a base plate 294 coupled to the muffle 92 at a pivot point. The heating laser 210 or the fiber optic connector 262 may be coupled to the base plate 294 along with the optical components 220, the beam splitter 230, the power detector 240, and the second beam splitter 270. The sight laser 250 (FIG. 6) may also be coupled to the base plate 294.

[0113] The base plate 294 may be rotatable about a pivot point to change the angle of the laser beam 202 relative to the glass ribbon 12, thereby changing its horizontal position (i.e., its position at the + / -X position of the coordinate axes of FIG. 11 ) relative to the glass ribbon 12. Rotation of the base plate 294 about the pivot point may be operable to position the laser beam 202 horizontally along the width of the glass ribbon 12, first half ribbon 62, or second half ribbon 82 to orient the laser beam 202 into the streaks 102.

[0114] 12, in an embodiment, an articulated arm laser beam delivery system 298 may be used to deliver the laser beam 202 from the heating laser 210 to the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82. The articulated arm laser beam delivery system 298 may comprise a number of moveable joints and a number of mirrors operable to direct the laser beam 202 from the heating laser 210 to the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82. The articulated arm laser beam delivery system 298 may provide a sealed beam path having a controllable atmosphere. The articulated arm laser beam delivery system 198 may be used in place of a fiber optic cable to deliver the laser beam 202 from the heating laser 210 located at a location remote from the glass ribbon 12 to a location proximate to the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82. In an embodiment, the articulating arm laser beam delivery system 298 may be operable to deliver a laser beam 202 having greater power than a laser beam 202 suitable for delivery through a fiber optic cable.

[0115] 2, 3, and 6, in an embodiment, the system may further include a control system 300. The control system 300 may include a processor 302, a memory module 304 communicatively coupled to the processor 302, and machine-readable and executable instructions 306 stored in the memory module 304. With reference to FIGS. 2 and 3, the control system 300 may be communicatively coupled to the system 200 for repairing streaks 102. With reference now to FIG. 6, when the control system 300 is communicatively coupled to the system 200 for repairing streaks 102, the control system 300 may be communicatively coupled to the heating laser 210, the power detector 240, or both.

[0116] Referring again to FIG. 6 , the control system 300 may be operable to maintain the stability of the laser beam 202 over time to maintain consistent operation of the system 200. As previously mentioned, the system 200 may include a beam splitter 230 operable to split the heating beam 202 into a pass portion 232 and a measurement portion 234. The measurement portion 234 of the laser beam 202 may be directed to a power detector 240. The control system 300 may receive an output from the power detector 240 and control the heating laser 210 using the output from the power detector 240. In particular, the machine-readable and machine-executable instructions 306, when executed by the processor 302, may cause the system to automatically receive a signal from the power detector 240 indicative of the power of the laser beam 202, determine a measured power of the laser beam 202 from the signal received from the power detector 240, and adjust the power output of the heating laser 210 based on the measured power of the laser beam 202. The computer readable and executable instructions 306 may include instructions for performing any of the other method steps discussed herein.

[0117] 3 and 6, the method of the present disclosure for repairing streaks will be further discussed. Any of the following method steps may be accomplished using the control system 300 through execution of computer readable and executable instructions 306 by the control processor 302. The method for repairing streaks 102 during a glass ribbon forming process may include forming the glass ribbon 12 using a glass forming process, which may be any of the glass ribbon forming processes previously described herein. The method may include maintaining the glass ribbon 12 under tension during the glass ribbon forming process. The method may further include maintaining the glass ribbon 12 under tension during the glass ribbon forming process. The method may further include maintaining the glass ribbon 12 under tension, such that the rate of change of thickness of the glass ribbon 12 per unit width of the glass ribbon 12 is less than about 3 nm. t / mm W More than 4 nm t / mm W or more, about 5nm t / mm W or more, about 10nm t / mm W or more, about 20nm t / mm W or more, or even about 30 nm t / mm W Above, about 1 nm t / mm W The method may include identifying streaks 102 in the glass ribbon 12 at locations along a width W of the glass ribbon 12 that is equal to or greater than 100 mm. The streaks 102 may have a streak width Ws (FIG. 4) of about 50 mm or less. Identification of the streaks 102 may be accomplished by any of the techniques previously described herein. The streaks 102 may have any of the other features or characteristics previously described herein for the streaks 102. The method further includes directing a laser beam 202 to the location of the streaks. The laser beam 202 may have a wavelength of about 1 μm to about 12 μm. The laser beam 202 may have any of the other features or characteristics previously discussed herein. The laser beam 202 heats the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82 at or near the streak location. Heating the glass ribbon 12, first half ribbon 62, or second half ribbon 82 at or adjacent to the locations of the streaks reduces the viscosity of the glass, thereby reducing the thickness of the glass ribbon 12 at the locations of the streaks, reducing the rate of change of the thickness of the glass ribbon 12 at the locations of the streaks, or both.

[0118] The laser beam 202 may have a linear average power density of about 10 mW / mm to 10 W / mm. The laser beam 202 may have a power of about 0.1 Watts (W) to about 50 W, depending on the width and thickness of the streak, the wavelength of the laser beam, and the vertical position of the laser beam 202. The laser beam 202 may have a full width at half maximum of less than the change in thickness of the glass ribbon 12 across the streak width, and the beam width is less than 1 / e of the laser beam 202 at the point where the laser beam 202 is incident on the glass ribbon 12. 2In embodiments, the laser beam 202 may have a beam width that is about 50 mm or less, about 40 mm or less, about 30 mm or less, about 20 mm or less, or about 10 mm or less. The laser beam 202 may have any of the other characteristics or properties previously described herein for the laser beam 202, such as power, wavelength, width, position, shape, intensity distribution, etc.

[0119] Any of the methods disclosed herein may further include determining a width, a thickness profile, or both of the streak 102, and adjusting one or more of a power, position, shape, intensity distribution, or combinations thereof of the laser beam 202 based on the width, thickness profile, or both of the streak 102. In an embodiment, the method may include determining a thickness profile of the glass ribbon 12 at the streak location, such as across a streak width of the streak 102, and modifying at least one of a shape or intensity distribution of the laser beam 202 based on the thickness profile of the glass ribbon 12 across the width of the streak. In an embodiment, the laser beam 202 may have a top hat intensity distribution or a Gaussian intensity distribution.

[0120] In an embodiment, the streak 102 may be a protruding streak that protrudes outwardly from the glass ribbon 12, and the method may include directing the laser beam 202 at a center of the streak 102. With reference to FIG. 8A , in an embodiment, the streak 102 may be a concave streak, and the method may include splitting the laser beam 202 into a first beam 272 and a second beam 274 spaced apart from the first beam 272, and directing the first beam 272 and the second beam 274 proximate an outer edge of the streak 102. 10, in an embodiment, any of the methods disclosed herein may further include identifying a first streak 102A and a second streak 102B, splitting the laser beam 202 into a first beam 272 and a second beam 274, directing the first beam 272 to the first streak 102A, and directing the second beam 274 to the second streak 102B. The first streak 102A and the second streak 102B may be identified using any of the methods previously described herein. In the case of a concave streak or multiple streaks, splitting the laser beam 202 may include passing the laser beam 202 through a beam splitter, such as the second beam splitter 270 of FIGS. 8A and 10. Directing the first beam 272 and the second beam 274 onto the first streak 102A and the second streak 102B, or onto the outer edge of the streak 102 in the case of concave streaks, may include passing the first beam 272, the second beam 274, or both, through one or more optical components operable to redirect and / or focus the beam at the target location.

[0121] In an embodiment, any of the methods disclosed herein may include locating the laser beam 202 using a site laser beam 252 reflected along the beam path of the laser beam 202. The site laser beam 252 may have a wavelength in the range of about 400 nm to about 700 nm. The site laser beam 252 may have any of the characteristics or properties previously described herein for a site laser beam. In an embodiment, directing the laser beam 202 to the streak 102 may be performed by determining whether the glass of the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82 is greater than about 1×10 4 Poise to about 7.6 x 10 7.6 This can include positioning the laser beam 202 at a location along the streak 102 having a viscosity in the poise range. In an embodiment, the location can be a vertical location along the streak 102, such as in a fusion downdraw or slot-draw process.

[0122] 3 and 5, in an embodiment, identifying the streak 102 may include illuminating the glass ribbon 12 with light 114 from the inspection light source 110 and identifying a light band 116, a dark band 118, or both, caused by refraction of the light 114 due to a change in thickness of the glass ribbon 12 at the location of the streak 102. The light band 116 and the dark band 118 may identify the location of the streak 102. In an embodiment, directing the laser beam 202 to the location of the streak may include directing the laser beam 202 to the glass ribbon 12, where the laser beam 202 initially has a first power level sufficient to cause a change in thickness of the glass ribbon 12. The method may further include measuring a change in thickness of the glass ribbon 12 in response to the laser beam 202. The change in thickness of the glass ribbon 12 in response to the laser beam 202 may identify a location of the laser beam 202 on the glass ribbon 12. The method may further include adjusting the position of the laser beam 202 to the location of the streak and reducing the power of the laser beam 202 to a second power level sufficient to repair the streak.

[0123] The method of manufacturing a glass sheet can include forming a glass ribbon 12 using a glass forming process, which can be any of the glass ribbon forming processes previously described herein. The method can include maintaining the glass ribbon 12 under tension during the glass ribbon forming process. The method can further include maintaining a rate of change of thickness of the glass ribbon 12 per unit width of the glass ribbon 12 under tension of about 3 nm. t / mm W More than 4 nm t / mm W or more, about 5nm t / mm W or more, about 10nm t / mm W or more, about 20nm t / mm W or more, or even about 30 nm t / mm W Above, about 1 nm t / mm WThe method may include identifying a streak 102 in the glass ribbon 12 at a location along a width W of the glass ribbon 12 that is equal to or greater than 100 mm. The streak 102 may have a streak width Ws (FIG. 4) of 50 mm or less. Identifying the streak 102 may be accomplished by any of the techniques previously described herein. The streak 102 may have any of the other features or characteristics previously described herein for the streak 102. The method further includes directing a laser beam 202 to the location of the streak. The laser beam 202 may have a wavelength of about 1 μm to about 12 μm. The laser beam 202 may have any of the other features or characteristics previously discussed herein. The laser beam 202 heats the glass ribbon 12, the first half ribbon 62, or the second half ribbon 82 at or near the streak location. Heating the glass ribbon 12, first half ribbon 62, or second half ribbon 82 at or adjacent to the locations of the streaks reduces the viscosity of the glass, thereby reducing the thickness of the glass ribbon 12 at the locations of the streaks, reducing the rate of change of the thickness of the glass ribbon 12 at the locations of the streaks, or both.

[0124] The embodiments of the present disclosure may be embodied in hardware and / or software (including firmware, resident software, microcode, etc.). The control system 300 of the system 200 and / or other controllers for the glass forming apparatus 10 may include at least one control processor 302 and a computer-readable storage medium (i.e., memory module 304) as previously described herein. The control system 300 may be communicatively coupled to one or more system components (e.g., heating laser 210, power detector 240, sight laser 250, streak inspection system 108, etc.) via any wired or wireless communication path. The computer usable or computer readable storage medium or memory module 304 may be any medium capable of storing, storing, communicating, propagating, or transporting a program for use by or in connection with an instruction execution system, apparatus, or device.

[0125] The computer usable or computer readable storage medium or memory module 304 may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or propagation medium. More specific examples (non-exhaustive list) of computer readable storage medium or memory module 304 may include an electrical connection having one or more wires, a portable computer diskette, a random access memory (RAM), a read only memory (ROM), an erasable programmable read only memory (EPROM or flash memory), an optical fiber, and a portable compact disk read only memory (CD-ROM). It should be noted that the computer usable or computer readable storage medium or memory module 304 may even be a paper or other suitable medium on which the program is printed, since the program may be captured electronically, for example, via optical scanning of the paper or other medium, and then compiled, interpreted, or processed in any other suitable manner, as appropriate, and then stored in the computer memory.

[0126] The computer readable storage medium or memory module 304 may include machine readable and machine executable instructions 306 for performing operations of the system 200 or methods of repairing streaks using the system 200 of the present disclosure. The machine readable and machine executable instructions 306 may include computer program code, which may be written in a high level programming language, such as C or C++, for ease of development. Additionally, computer program code for performing operations of the present disclosure may also be written in other programming languages, such as, but not limited to, interpreted languages. Some modules or routines may be written in assembly or microcode to improve performance and / or memory usage. However, software embodiments of the present disclosure do not depend on implementation in a particular programming language. It will be further understood that any or all of the functionality of the program modules may also be implemented using discrete hardware components, one or more application specific integrated circuits (ASICs), or programmed digital signal processors or microcontrollers.

[0127] Working Example The embodiments described herein will be further clarified by the following non-limiting examples.

[0128] Example 1. Streak repair using a laser beam

[0129] In Example 1, a low power CO2 laser beam was used to repair streaks in a glass ribbon produced by a fusion downdraw process as shown in FIG. 1. The wavelength of the CO2 laser beam was 10.6 μm. The laser beam was passed through a polycrystalline fiber optic cable and collimated using a collimating lens comprising a ZnSe lens. The laser beam was then irradiated onto the identified streaks on the glass ribbon. A portion of the laser beam was reflected to a power detector to monitor the power of the laser. The power of the laser beam of Example 1 as a function of time is shown in FIG. 13 and identified by reference numeral 1302.

[0130] The relative severity of the streaks was evaluated at time intervals before and after directing the laser beam at the streaks. The relative severity of the streaks was based on the thickness profile of the glass ribbon in the area of ​​the streaks, providing an indication of the degree of thickness change at the streaks. Referring now to FIG. 13, the relative severity of the streaks (y-axis) as a function of time (x-axis) is plotted along with the power of the laser beam. In FIG. 13, reference numeral 1304 refers to the relative severity of the streaks on the A-side of the glass ribbon, the side on which the laser beam is incident, and reference numeral 1306 refers to the relative severity of the streaks on the B-side of the glass ribbon. As shown in FIG. 13, applying a laser beam having a power of 1% to the streaks on the glass ribbon 12 reduced the severity of the streaks by more than 50% (reduced the severity from an average of 0.8 to less than 0.4) compared to the severity of the streaks prior to applying the laser beam. This shows that the severity of the streaks can be significantly reduced by irradiating them with a laser beam.

[0131] Example 2: Operation of the positioning stage to position the laser beam

[0132] In Example 2, the horizontal position of the laser beam on the glass ribbon was varied using a positioning stage to evaluate the change in glass thickness with respect to changes in the position and power of the laser beam. In Example 2, the glass ribbon was produced by a fusion downdraw process. As illustrated in FIG. 11, a positioning stage comprising a base plate that can be swung about a pivot point was coupled to the muffle of the fusion downdraw process at the window of the muffle. The heating laser and optical components were coupled to the base plate of the positioning stage. The horizontal position of the positioning stage was such that when the swing angle of the positioning stage was equal to zero, the laser beam generated by the system was incident on the glass ribbon at a position about 1310 mm from the inlet end of the forming body of the fusion downdraw process. The same CO2 laser and optical components as in Example 1 were used to generate the laser beam of Example 2. The swing angle and power of the laser beam were varied, and the thickness of the glass ribbon in response to the laser beam was monitored. Referring to FIG. 14, the change in thickness of the glass ribbon 12 as a function of horizontal position is plotted for each change in the operating parameters of the laser and the positioning stage. The pivot angles, laser powers and reference numbers in FIG. 14 for each setting of the system of Example 2 are provided in the table below.

[0133] [Table 1]

[0134] Referring again to FIG. 14, reference numeral 1402 provides a baseline thickness profile of the glass ribbon with no laser beam incident on the glass ribbon. The thickness data at reference numeral 1404 shows a valley at approximately 1310 mm, indicated by point number 1 in FIG. 14, which indicates the location where the laser beam incidents and falls on the glass ribbon. The valley at point number 1 in FIG. 14 indicates that a laser beam with 8% of the maximum power results in a reduction of approximately 2.5 thickness units compared to the thickness of the glass ribbon without the laser beam (reference numeral 1402), with each thickness unit in FIG. 14 equal to 0.001 mm (e.g., 2.5 thickness units equal to a thickness change of 0.0025 mm). As the rocking angle increases from 0 degrees to 20.5 degrees, the location of the valley, which corresponds to the location of the laser beam, shifts to the right in the direction of decreasing distance from the entrance end. Point 2 corresponds to the laser beam location at reference numeral 1406. Point 2 corresponds to the laser beam position of reference number 1406 (angle 12 degrees), and point 3 indicates the laser beam position of reference number 1408 (angle 18 degrees). 1408 (angle 18 degrees) and point 4 indicate the laser beam position of reference number 1410 (angle 20.5 degrees). 1410 (20.5 degrees). In this way, when the oscillation angle of the positioning stage changes, the position of the laser beam also changes. If the oscillation angle of the positioning stage is 20 degrees, the position of the laser beam can be adjusted by a width of about 160 mm.

[0135] Furthermore, lowering the power reduces the magnitude of the thickness change compared to no laser beam (1402). At 5% laser power (reference numbers 1406 and 1408), the thickness difference is reduced by about 20% compared to 8% laser power (e.g., from about 2.5 thickness units (i.e., 0.0025 mm) to about 2.0 thickness units (i.e., 0.0020 mm) in FIG. 14). Further reducing the power to 3% (reference number 1410) reduces the thickness difference by about 60% compared to 8% laser power (e.g., from about 2.5 thickness units (i.e., 0.0025 mm) to about 1.0 thickness unit (i.e., 0.0020 mm)). Example 2 shows that the heating effect of the laser beam can be adjusted by changing the power of the laser. Thus, the degree to which the laser beam reduces the severity of the streaks can be altered by changing the power of the laser.

[0136] Based on the foregoing, it should be appreciated that the embodiments described herein relate to glass forming processes for producing glass ribbons and methods for reducing the severity of streaks in glass ribbons. Although various embodiments and techniques for producing glass ribbons and repairing streaks in glass ribbons are illustrated and described herein, it should be understood that it is contemplated that each of these embodiments and techniques may be used separately or in combination with one or more of the embodiments and techniques.

[0137] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Accordingly, it is intended that the present specification cover such modifications and variations of the various embodiments described herein, provided that such modifications and variations come within the scope of the appended claims and their equivalents. [Explanation of symbols]

[0138] 12 Glass Ribbon 44 First molding surface 45 Second molding surface 46 Base 50 Molded body 51 Trough 53 Base 60 First Weir 62 First Half Ribbon 80 Second Weir 82 Second Half Ribbon 90 Tension roller 100 Code 200 Systems 202 Laser Beam 300 Control System 302 Processor 304 Memory Module

Claims

1. 1. A method for repairing streaks during a glass ribbon forming process, comprising: forming a glass ribbon; maintaining the glass ribbon under tension; The rate of change in thickness of the glass ribbon per unit width of the glass ribbon is 1 nm t / mm W identifying first streaks in the glass ribbon at locations along a width of the glass ribbon that are equal to or greater than 50 mm, wherein the first streaks have a width of 50 mm or less; directing a laser beam at the location of the first streak, the laser beam having a wavelength of 1 μm to 12 μm, the laser beam heating glass of the glass ribbon at the location of the first streak; heating the glass at the first streak locations to reduce the viscosity of the glass and reduce the thickness of the glass ribbon at the first streak locations, the rate of change of the thickness of the glass ribbon at the first streak locations, or both; A method comprising: a body including an inlet and an outlet, said inlet and outlet aligning with corresponding openings in an associated furnace, said inlet and outlet defining a flow path within the body; an inductor secured to a portion of the body and configured to draw molten metal from an associated furnace into the flow channel; a wall notch spaced apart from the inlet and outlet provided in the molding body; a dam assembly disposed adjacent to at least one of the inlet and the outlet, the dam assembly being movable between a raised position and a lowered position; Apparatus in which molten metal flows back into an associated furnace when the dam assembly is in the raised position, and molten metal rises within the channel and can reach the wall notch when the dam assembly is in the lowered position.

2. 10. The method of claim 1, wherein the laser beam comprises an average linear power density of 10 milliwatts per millimeter (mW / mm) to 10 watts per millimeter (W / mm).

3. a beam width of the laser beam at a point where the laser beam is incident on the glass that is less than or equal to a full width at half maximum of a change in thickness of the glass ribbon across a width of the first streak, and the beam width is 1 / e 2 The method of claim 1 or 2, wherein the width is defined as the width.

4. 10. The method of claim 1, further comprising determining a width, a thickness profile, or both, of the first streak, and adjusting one or more of a power, a position, a shape, an intensity distribution, or a combination thereof, of the laser beam based on the width, the thickness profile, or both, of the first streak.

5. The method of claim 1 , wherein the laser beam comprises a top-hat intensity distribution or a Gaussian intensity distribution.

6. The method of claim 1 , wherein the first streak is a protruding streak, the method comprising directing the laser beam at a center of the first streak.

7. 2. The method of claim 1, wherein the first streak is a concave streak, the method comprising: splitting the laser beam into a first beam and a second beam spaced apart from the first beam; and directing the first beam and the second beam to a position proximate an outer edge of the first streak.

8. 1. A system for repairing streaks in a glass ribbon, comprising: a laser producing a laser beam having a wavelength of 1 micrometer to 12 micrometers and a beam width less than or equal to the full width at half maximum of the change in thickness of the glass ribbon across the streak width at the streak location, the beam width being 1 / e 2 a laser beam having a width defined as a width determined at the point where the laser beam is incident on the glass ribbon; one or more optical components operable to change one or more characteristics of the laser beam; Equipped with The system, wherein the laser and the one or more optical components are positioned to direct the laser beam to the streak location.

9. 9. The system of claim 8, further comprising: a power detector; and at least one beam splitter operable to split the laser beam into a pass portion and a measurement portion, the at least one beam splitter operable to direct the pass portion of the laser beam to the streak location and direct the measurement portion of the laser beam to the power detector.

10. 10. The system of claim 9, wherein the one or more optical components comprise a diffractive optical component operable to change the shape, intensity distribution, or both of the laser beam.

11. 10. The system of claim 8, further comprising a fiber optic cable extending from the laser to a location proximate to the glass ribbon, and a fiber optic connector coupled to an end of the fiber optic cable, the fiber optic cable operable to deliver the laser beam from the laser to a location proximate to the glass ribbon.

12. 10. The system of claim 8, further comprising an articulating arm laser beam delivery system coupled to the laser, the articulating arm laser beam delivery system comprising a plurality of moveable joints and a plurality of mirrors operable to direct the laser beam from the laser through an enclosed beam path having a controllable atmosphere at the glass ribbon.

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