JP2018521941A - Glass article having laser-cut edges and method for producing the same - Google Patents

Abstract

Disclosed herein is a glass article, such as a light guide plate, having a first surface, an opposite second surface, and a thickness extending therebetween, and no more than about 35% of the thickness of the glass article. A glass article comprising a laser ablation region having a thickness, or at least one side edge comprising a chamfer having a height of about 15% or less of the thickness of the glass article. This document also discloses a display device including such a glass article and a method for manufacturing such a glass article.

Description

Cross-reference of related applications

  This application claims the benefit of priority under 35 USC 119 of US Provisional Application No. 62/162373, filed May 15, 2015, and relies on the contents of this application, The entirety is incorporated herein by reference.

  The present disclosure relates generally to glass articles and display devices including such glass articles, and more specifically to glass light guides having at least one laser cut edge and methods of manufacturing the same.

  Liquid crystal displays (LCDs) are commonly used in various electronic devices such as mobile phones, laptop computers, electronic tablets, televisions, and computer monitors. With the growing demand for larger and higher resolution flat panel displays, there is a need for large, high quality glass substrates for use in these displays. For example, a glass substrate may be used as a light guide plate (LGP) in an LCD, and a light source may be coupled to the light guide plate. The thinness and / or screen size of the LCD device may be affected by the size and / or nature of the light emitting and / or light incident surface of the light guide.

  Current light guides are often manufactured from polymethylmethacrylate (PMMA). However, PMMA has a relatively high coefficient of thermal expansion (for example, a coefficient of thermal expansion that is almost an order of magnitude larger than that of glass), and when designing an LCD device, the light source such as an LED and a light guide May require more space. This gap may reduce the efficiency of light coupling from the light source to the light guide and / or require a larger bezel to hide the edges of the display. Furthermore, due to its relatively fragile mechanical strength, it may be difficult to produce a light guide that is large and thin enough to meet current consumer demand from PMMA. Therefore, PMMA light guides limit the area of the light emitting surface that can be used to display an image because it is hidden by the bezel or cannot produce a large enough plate for the desired display size. there is a possibility.

  Glass light guides have been proposed as an alternative to PMMA due to low light attenuation, low thermal expansion coefficient, and high mechanical strength. However, the area of the light incident surface of the glass substrate may be affected by the method of cutting the glass. For example, glass can be cut by mechanical scoring techniques that provide dashed perforations that can break the glass relatively straight, but this method can be chipping, cracking, and / or Substantial damage, such as breakage, can occur on the edge of the glass. Defects at the edge of the glass are often found around the intersection area between the major surface and the edge, for example, a 90 ° ridge angle. In order to improve reliability and reduce defects, glass edges can often be finished by the introduction of chamfers, which can remove all or part of the damaged part of the glass. is there. For example, in the case of a 0.7 mm thick glass plate, about 0.2 mm of the thickness may be ground or polished so as to generate the chamfered portions as described above at each corner of the side edge.

  Although this technology can improve the reliability of the glass, this chamfer may reduce the surface area at the edge of the light guide that can be used to couple light from the light source to the light guide, It may have an adverse effect from an optical point of view. For example, a 0.2 mm chamfer on a 0.7 mm thick glass plate can cause a reduction of about 14% or more in coupling efficiency compared to a flat, non-chamfered edge. Therefore, reducing the chamfering of the light incident edge would be advantageous because a thinner light guide and thus a thinner LCD device could be possible. It would also be advantageous to provide an improved method for finishing the edges of the light guide plate so as to increase the surface area of the light incident edge available for coupling with the light source.

  The present disclosure, in various embodiments, is a glass article, such as a light guide, having a first surface, an opposing second surface, and a thickness extending therebetween, and the glass article. And a glass article comprising at least one side edge including a laser ablation region having a thickness of about 35% or less of the thickness. The present disclosure also provides a glass article having a first surface, an opposite second surface, and a thickness extending therebetween, and a height of about 15% or less of the thickness of the glass article. And a glass article including at least one side edge including a chamfered portion. Furthermore, a display device including such a glass article is disclosed herein.

  In certain embodiments, the side edge can include a non-laser ablation region or a non-chamfered region. According to various embodiments, the scattering parameter of the light incident surface of the laser ablation region can be less than 0.1, and the scattering parameter of the light incident surface of the non-laser ablation region can be less than about 0.2. The scattering parameter of the light incident surface of the chamfered region or the non-chamfered region can be less than about 0.1 in a non-limiting embodiment. In a further embodiment, a display device including the light guide may further include a light source such as a light emitting diode (LED) coupled to the at least one side edge. According to various embodiments, the light source can be coupled to the at least one side edge in close proximity to the non-laser ablation region or the non-chamfered region.

  Also disclosed is a method for manufacturing such a glass article or glass light guide plate, the method providing a glass plate having a first surface, an opposing second surface, and a thickness extending therebetween. Forming a defect line by bringing a laser into contact with the glass plate along a predetermined path on the first surface; and laser ablation having a thickness of about 35% or less of the thickness of the glass plate. Separating the glass sheet into two or more portions along the defect line to form a glass article including at least one side edge including a region.

  Further disclosed herein is a method for manufacturing a glass article that includes a first surface, an opposing second surface, and a thickness extending therebetween. Providing a glass plate having, forming a groove by bringing a laser into contact with the glass plate along a predetermined path on the first surface, and about 15% or less of the thickness of the glass plate Separating the glass sheet into two or more portions along the groove to form a glass article including at least one side edge including a chamfer having a height.

  In various embodiments, the predetermined path can include a straight line that can be perpendicular to an adjacent side edge of the glass sheet. According to a further embodiment, the defect line includes a laser ablation hole extending into the glass plate to a depth of about 35% or less of the thickness of the glass plate, and / or the second surface from the first surface. A plurality of fault lines extending in a direction substantially perpendicular to the surface of the substrate. In yet another embodiment, separating the glass sheet into two or more portions can include applying mechanical or thermal stress on or around the defect line or groove.

  Additional features and advantages of the disclosure will be set forth in the detailed description that follows, and in part will be readily understood by those skilled in the art from the description, including the following detailed description, claims, and claims. It will be appreciated by performing the method described in the accompanying drawings.

  Both the foregoing summary and the following detailed description present various embodiments of the disclosure and are intended to provide an overview or framework for understanding the nature and characteristics of the claims. Should be understood. The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. These drawings illustrate various embodiments of the present disclosure and, together with the detailed description, serve to explain the principles and operations of the present disclosure.

  The following detailed description can be further understood when read in conjunction with the following drawings, in which like reference numerals indicate like elements, when possible, and the accompanying drawings are not necessarily accurate. It can be seen that it is not drawn to scale.

Figure 3 shows a glass article having side edges including two mechanically formed chamfers. 2 is a plot of optical coupling efficiency of the glass article of FIG. 1 as a function of chamfer height. Figure 3 shows a side edge of an exemplary glass article including a laser ablation region. 2 is an SEM cross-sectional image of a glass article including a laser ablation region according to various embodiments of the present disclosure. 1 illustrates a glass article including a laser ablation region according to certain embodiments of the present disclosure. 5 is a plot of the optical coupling efficiency of the glass article of FIG. 4 as a function of laser ablation zone thickness. 1 illustrates a glass article including a laser ablation region according to certain embodiments of the present disclosure. 1 illustrates a glass article including a laser ablation region according to certain embodiments of the present disclosure. 6B is a plot of the optical coupling efficiency of the glass article of FIGS. 6A and 6B as a function of laser ablation zone thickness. FIG. 6B is a plot of the optical coupling efficiency of the glass article of FIGS. 6A and 6B as a function of laser ablation zone thickness. FIG. Figure 6 is a plot of optical coupling efficiency as a function of scattering parameter Sigma. FIG. 6 illustrates a glass article having a side edge including a chamfer from one laser cut in accordance with various embodiments of the present disclosure. FIG. FIG. 6 illustrates a glass article having a side edge including a chamfer from one laser cut in accordance with various embodiments of the present disclosure. FIG. 2 illustrates a method for manufacturing a glass article according to various embodiments. 2 illustrates a method for manufacturing a glass article according to various embodiments. 2 illustrates a method for manufacturing a glass article according to various embodiments.

Glass Article Disclosed herein includes a first surface, an opposing second surface, and a thickness extending therebetween, and a thickness of about 35% or less of this thickness of the glass article. A glass article including at least one side edge including a laser ablation region having. Exemplary glass articles can include, but are not limited to, glass light guide plates. The present disclosure also includes a first surface, an opposite second surface, and a chamfer having a thickness extending therebetween and a height of about 15% or less of the thickness of the glass article. And a glass article comprising at least one side edge. Furthermore, a display device including such a glass article is disclosed herein.

  This glass article or glass light guide plate includes but is not limited to aluminosilicate glass, alkali aluminosilicate glass, borosilicate glass, alkali borosilicate glass, aluminoborosilicate glass, alkali aluminoborosilicate glass, and other suitable glasses. May include any material known in the art for use in non-displays or other similar devices. In certain embodiments, the glass article may have a thickness of about 3 mm or less, such as a thickness ranging from about 0.3 mm to about 2 mm, a thickness ranging from about 0.7 mm to about 1.5 mm, or about It may have a thickness ranging from 1.5 mm to about 2.5 mm, including all these ranges and subranges. Non-limiting examples of commercially available glasses suitable for use as light guide plates include, for example, Corning® EAGLE XG® glass, Gorilla® glass, Iris® glass, Lotus ™ glass, and Willow® glass.

  The glass article may include a first surface and an opposite second surface. These surfaces, in certain embodiments, may be planar or substantially planar, eg, substantially flat and / or horizontal. The first surface and the second surface may be parallel or substantially parallel in various embodiments. The glass article may further include at least one side edge, such as at least two side edges, at least three side edges, or at least four side edges. As a non-limiting example, the glass article may include a rectangular or square glass plate with four edges, but other shapes and configurations are envisioned and are intended to be within the scope of this disclosure. ing.

  FIG. 1 shows a glass article, such as a glass light guide, including a chamfer created by polishing following a mechanical score and break technique. The illustrated glass article 100 can include a first surface 105, a second surface 110, and side edges 115. A thickness T of the glass article 100 extends between the first surface and the second surface. After mechanical scoring and cleaving, edge defects on the side edges 115 can be removed by grinding and / or polishing to produce a mechanically formed chamfer 120. These chamfers 120 can have a height h. An exemplary height h of the chamfer 120 can be at least about 25% of the total thickness T of the glass article. For example, in the case of a 0.7 mm thick glass plate, a chamfer having a height of about 0.2 mm can be used to correct defects at both corners of the side edge 115. The chamfer 120 can be cut at any suitable angle ranging from about 30 ° to about 60 °, such as, for example, about 45 °.

  A light source 140 such as an LED can be coupled to the side edge 115. The light source can have a height H, which can be at least about 50% of the total thickness T of the glass article, for example, at least about 60% of the thickness T of the glass article, It can be at least about 70%, at least about 80%, at least about 90%, or 100%. A light source having a height H that exceeds the thickness T of the glass article can also be used in some embodiments. To cover a gap having a gap width D between the light source 140 and the side edge 115, a reflector 150 can be included on a surface that is very close to or adjacent to the light source 140, and in FIG. A reflector 150 adjacent to 110 is shown. According to a non-limiting embodiment, the light source can be a distance D from the side edge of the glass article, the distance D can range from, for example, about 0.01 mm to about 2 mm, for example , About 0.04 mm to about 1.8 mm, about 0.5 mm to about 1.5 mm, about 0.6 mm to about 1.2 mm, or about 0.8 mm to about 1 mm, Includes all ranges and subranges.

  FIG. 2 is a plot of optical coupling efficiency as a function of chamfer height with and without a reflector for the glass article shown in FIG. The model of this graph is a glass thickness T 0.7 mm, a light source (LED) height H 0.5 mm, a gap width D 0.04 mm, a 45 ° chamfer, a glass refractive index (Nd) = 1.497, and a reflectance of 99%. And the assumption of a reflector with Lambertian scattering. As shown in FIG. 2, the optical coupling efficiency decreases as the height h of the chamfered portion increases. For light guides with side edges not chamfered (height = 0), the optical coupling efficiency can be as high as 91% with a reflector or 88% without a reflector. It has been shown that by chamfering the edge to a height of 0.2 mm, the optical coupling efficiency is reduced by 11% with the reflector or 14% without the reflector. Thus, FIG. 2 shows that chamfering to reduce edge defects can result in undesirable light loss. Another edge finishing method with reduced light loss would advantageously provide a larger and / or thinner display with improved display.

  According to the first embodiment shown in FIG. 3A depicting a cross-sectional view of a side edge 215 of a glass article 200 that includes a laser ablation region 225, the laser ablation region 225 can be, for example, a plurality of laser ablation holes or damage marks 230. Can be included. The glass in the laser ablation region 225 can be modified via nonlinear effects by a high energy density laser. Thus, by scanning the laser along a predetermined line or path, a defect line can be created that can define the outer periphery or shape of one or more glass pieces to be separated from the glass plate. The laser ablation region may not penetrate through the entire thickness T of the glass article 200 in certain embodiments. For example, the thickness t1 of the laser ablation region 225 can be less than about 35% of the thickness T of the glass article, for example, less than about 30%, less than about 25%, or less than about 20% of the thickness T, between them Including all ranges and subranges. In various embodiments, the thickness T of the glass article 200 can be about 3 mm or less, such as about 0.3 mm to about 2 mm, about 0.7 mm to about 1.5 mm, or about 1.5 mm to about 2.5 mm. Including all ranges and subranges between them. Thus, in certain embodiments, the thickness t1 of the laser ablation region 225 can be about 1 mm or less, such as from about 0.05 mm to about 0.9 mm, from about 0.1 mm to about 0.8 mm, from about 0.2 mm. It can range from about 0.7 mm, about 0.3 mm to about 0.6 mm, or about 0.4 mm to about 0.5 mm, including all ranges and subranges therebetween. In some embodiments, the thickness t1 of the laser ablation region may vary, for example, it may vary linearly or may vary randomly. Thus, the thickness t2 will also vary with t1.

  The remaining portion of the side edge 215 may include non-laser ablation regions 235, for example, regions that do not include laser ablation holes and / or non-linearly modified portions. This region 235 can have any thickness t2 such that t1 + t2 = T. For example, the thickness t2 of the non-laser ablation region 235 can be greater than about 65% of the thickness T of the glass article, for example, greater than about 70% of the thickness T, greater than about 75% of the thickness T, or thickness. It can be greater than about 80% of T, including all ranges and subranges between them. In some embodiments, the thickness t2 can be less than about 2 mm, for example, ranging from about 0.25 mm to about 1.5 mm, from about 0.5 mm to about 1.2 mm, or from about 0.8 mm to about 1 mm. Including all ranges and subranges between them. In FIG. 3A, laser ablation region 225 is shown adjacent to first surface 205 and non-laser ablation region 235 is shown adjacent to second surface 210, but their placement and designation can be interchanged without limitation. It should be understood that these surfaces are only referred to herein as “first” and “second” for discussion.

  FIG. 3B is a scanning electron microscope image (SEM image) of a cross-section of the side edge of a glass article comprising “Corning” “Iris” glass of 0.7 mm thickness. As described above with respect to FIG. 3A, this side edge may include a laser ablation region 225 and a non-laser ablation region 235. As is apparent from FIG. 3B, the laser ablation region has been modified to a predetermined depth via nonlinear effects by powerful laser energy. In the illustrated embodiment, the thickness t1 of the laser ablation region is 0.24 mm, whereas the total thickness T of the glass substrate is 0.7 mm. Therefore, as shown, t1 / T = 0.34, for example, t1 is about 35% or less of the total thickness T. The light incident surface of the laser ablation region 225 may have a scattering parameter (Sigma) of less than about 0.2 in certain embodiments, for example, a scattering parameter of less than about 0.15, or less than about 0.1. (Sigma). Similarly, the light incident surface of the non-laser ablation region 235 can have a scattering parameter (Sigma) of less than about 0.1, for example, a scattering parameter (Sigma) of less than about 0.05 or less. be able to. The Sigma scattering parameter can be proportional to the surface roughness of the region and can indicate the width of the Gaussian distribution on the projection plane. In certain embodiments, the non-laser ablation region 235 can have a scattering parameter that is smaller than the scattering parameter of the laser ablation region 225, and thus can have a relatively smooth light entrance surface. The relatively smoother surface of the non-laser ablation region 235 allows the glass plate to be separated into two or more parts by cracking or snapping along the defect line created by the laser. Sometimes it can be produced.

  A further schematic diagram of an exemplary glass article 200 is depicted in FIG. The glass article can have a thickness T extending between the first surface 205 and the second surface 210 and side edges 215. The side edge 215 can include a laser ablation region 225 having a thickness t1. A light source (e.g., LED) 240 having a height H is coupled to the side edge 215 and can be centered between the first surface 205 and the second surface 210, as described in more detail below. Any other arrangement can be used. First reflector 245 and / or second reflection adjacent to first surface 205 and / or second surface 210 to cover a gap having a gap width D between light source 240 and side edge 215. A body 250 can be placed. Suitable reflectors include broadband reflectors that cover the entire visible spectrum from about 420 nm to 700 nm. The first reflector is referred to herein as a “front” reflector and can indicate that this first surface is a light emitting surface, and the second reflector is referred to herein as a “back”. It can be called a reflector. However, these arrangements and designations can be interchanged without limitation, and these reflectors are referred to herein as "first" or "front" and "second" or "back" for purposes of discussion. It should be understood that it is only called.

  FIG. 5 is a plot of optical coupling efficiency as a function of thickness for the glass article shown in FIG. 4 for the laser ablation region with only the back reflector or the laser ablation region with the front and back reflectors. It is. The model of this graph is: glass thickness T 0.7 mm, light source (LED) height H 0.5 mm, gap width D 0.04 mm, LED aligned in the center along the side edge, glass refractive index (Nd) = 1.497, It includes the assumption of a Lambertian reflector with a reflectivity of 99% and a Gaussian function scattering of the laser ablation region with Sigma = 0.36. As shown in FIG. 5, the optical coupling efficiency decreases as the thickness t1 of the laser ablation region increases. For light guides without thickness of laser ablation (thickness = 0), the optical coupling efficiency is up to 91.5% with both front and back reflectors or 91 with no back reflector alone. Can be as high as%. See, for example, FIG. 3B, but when laser ablating the side edges to a depth of 0.24 mm, the optical coupling efficiency is 2.43% with both the front and back reflectors or only the back reflector. If not, it is shown to decrease by 2.38%. Thus, FIG. 5 refers to, for example, FIG. 2, but shows that the laser ablation region can produce at least about 8.6% improvement in optical coupling efficiency compared to the chamfered region on the side edge. Yes.

  When the edge of the light source is aligned with the non-laser ablation region 235 (eg, when the edge of the light source 240 is aligned with the second surface 250 as shown in the schematic of FIG. 6A), or the edge of the light source is aligned with the laser ablation region 225. (For example, when the edges of the light source 240 are aligned with the second surface 250 as shown in the schematic of FIG. 6B), slightly different results were obtained. Of course, the laser ablation region can abut the first surface as in FIG. 6A or the second surface as in FIG. 6B, and the light source is not shown, but the first surface; Or it should be understood that it can be aligned with the second surface as shown. Table I shows the experimental results for comparing the difference in coupling efficiency when LED light from these two regions is coupled. As shown in Table I below, when the light source is aligned with the non-laser ablation region 235, the loss of optical coupling efficiency is caused by a light guide with a “mirror” side edge, eg, a light guide without a laser ablation region. Compared to, it was 2.52% without the front reflector, or 1.71% with the front reflector. These results prove, inter alia, that the coupling efficiency is increased by the use of a front reflector. Furthermore, when the light source is aligned with the laser ablation region in the absence of the front reflector, the loss of optical coupling efficiency increases to 3.33%, due to the alignment of the light source with the non-laser ablation region or the smoother region. It shows that the coupling efficiency can be increased.

  FIGS. 7A and 7B are plots of optical coupling efficiency as a function of laser ablation region thickness with only the back reflector (FIG. 7A) or both the front and back reflectors (FIG. 7B). is there. Both graphs plot a comparison of the alignment of the light source with the laser ablation region on the side edge of the light guide plate or the alignment of the light source with the non-laser ablation region. The model of these graphs is a Lambertian reflector having a glass thickness T 0.7 mm, a light source (LED) height H 0.5 mm, a gap width D 0.04 mm, a glass refractive index (Nd) = 1.497, and a reflectance of 99%. And the assumption of Gaussian function scattering of the laser ablation region with Sigma = 0.36. With respect to both FIG. 7A and FIG. 7B, it is observed that the position of the light source can affect the coupling efficiency. For example, with a laser ablation region thickness of 0.24 mm, the improvement in coupling efficiency obtained when the light source is aligned with the non-laser ablation region is only for the back reflector compared to the light source aligned with the laser ablation region ( In FIG. 7A), it is 3.1%, and when there is a back reflector and a front reflector (FIG. 7B), it is 2.8%.

  The results shown in FIGS. 7A and 7B suggest that the surface properties of the side edges, such as smoothness or roughness, can significantly affect the coupling efficiency. FIG. 8 is a plot showing the optical coupling efficiency as a function of the scattering parameter (Sigma) proportional to the roughness of the glass surface. The model of this graph includes the assumptions of glass thickness T2 mm, light source (LED) height H1.5 mm, and gap width D1.4 mm. As shown in FIG. 8, as Sigma (or surface roughness) increases, the optical coupling efficiency generally decreases. However, in the region of 0 <Sigma <0.2, the loss of coupling efficiency is not as dramatic as seen in the rest of the curve. Therefore, it may be advantageous to employ a Sigma scattering parameter of less than 0.2 along the surface of the side edge. In some embodiments, the scattering parameter of the laser ablation region may be less than about 0.2, for example, less than about 0.15, or less than about 0.1. Similarly, scattering parameters in non-laser ablation regions can be less than about 0.1 or less than about 0.05.

  A laser cutting technique can also be used to provide a glass article having a chamfer as shown in FIGS. 9A and 9B. A method for producing such a glass article, for example, a light guide plate, will be described in further detail below. Similar to the glass article of FIGS. 4, 6A and 6B, the glass article 300 includes a first surface 305, a second surface 310, and a thickness T extending therebetween, and side edges 315. be able to. A portion of the side edge 315 may include a chamfer 360 that can be adjacent to the first surface or the second surface, with the chamfer 360 adjacent to the first surface 305 illustrated. Yes. The chamfer 360 can have a width w2 and a height h2. In some embodiments, the width w2 of the chamfer 360 can correspond to or be proportional to the width of the predetermined path created by the laser. For example, in some embodiments, the width w2 can be less than about 10 micrometers, such as less than about 8 micrometers, or less than about 5 micrometers, such as less than about 5 micrometers, about 4 micrometers. Less than, less than about 3 micrometers, less than about 2 micrometers, or less than about 1 micrometer. The width w2 can be equal to about half the width of the defect line created by the laser in various embodiments. In further embodiments, the width w2 can be at least about 10% of the total thickness T of the glass article, such as at least about 15%, at least about 20%, at least about 25%, or at least about 30% of the thickness T; Includes all ranges and subranges between them. In some embodiments, the height h2 of the chamfer 360 can correspond to or be proportional to the depth of the predetermined path created by the laser. The chamfer height h2 can be, for example, less than about 30% of the thickness T of the glass article, such as less than about 25%, less than about 20%, less than about 15%, less than about 10%, or about It can be less than 5%, including all ranges and subranges between them. For example, the height h2 of the chamfer can be less than about 1 mm, for example, about 0.05 mm to about 0.9 mm, about 0.1 mm to about 0.8 mm, about 0.2 mm to about 0.7 mm, about 0 mm .3 mm to about 0.6 mm, or about 0.4 mm to about 0.5 mm, including all ranges and subranges therebetween.

  The following Table II shows the light coupling efficiency for the glass article shown in FIGS. 9A and 9B when coupled to a light source (LED). This light source was aligned with the non-chamfered area of the side edge, for example, in the embodiment depicted in FIG. 9A, the edge of the light source was aligned with the second surface 310. Of course, it should be understood that the chamfered area can abut the first surface as shown, or abut the second surface, not shown. As shown in Table II below, when the light source is aligned with the non-chamfered region, the loss of optical coupling efficiency is compared to a light guide with a “mirror” side edge, eg, a light guide without a laser ablation region. Thus, it was 6.93% when there was no front reflector, or 5.32% when there was a front reflector. Therefore, like the laser ablation light guide plate, the coupling efficiency can also be increased by using a front reflector, and the chamfered portion by laser cutting should be referred to, for example, FIG. 2, but compared with the mechanically formed chamfered portion. Light loss.

  In particular, it was chamfered by laser cutting compared to the loss of optical coupling efficiency for a mechanically chamfered glass lightguide, which is 11% with a back reflector or 14% without a back reflector. The loss of light coupling efficiency for the glass light guide is almost halved. While not wishing to be bound by theory, this improvement is (a) only one chamfer by laser cutting in certain embodiments, as opposed to two mechanically formed chamfers. And / or (b) may be due to negligible defects and / or surface damage during laser cutting, as opposed to (b) mechanical scoring, cleaving, and polishing techniques Conceivable. Thus, in some embodiments, the glass light guide disclosed herein includes a single chamfer adjacent to either the first surface or the second surface, otherwise The loss of coupling efficiency that can be caused by the presence of another chamfer can be minimized.

  Furthermore, the loss of optical coupling efficiency is more than double compared to the laser ablation light guide when the LEDs are aligned in the non-laser ablation region. While not wishing to be bound by theory, this additional light loss may be induced depending on the method used to separate (eg, cleave) the (a) chamfer region 360 and / or (b) the glass plate. It is considered that there may be a case where the twist hackles 365 may be formed on the light body. The twist hackles may be formed, for example, when the glass plate is cleaved following laser scribing using mechanical force, as described in further detail below.

Also disclosed herein is a method for manufacturing a glass article or glass light guide plate, the method having a first surface, an opposite second surface, and a thickness extending therebetween. Providing a glass plate; contacting the glass plate with a laser along a predetermined path on the first surface to form a defect line; and a thickness of about 35% or less of the thickness of the glass plate. Separating the glass sheet into two or more portions along the defect line to form a glass article including at least one side edge including a laser ablation region having

  There is further disclosed herein a method for manufacturing a glass article or glass light guide, the method comprising a first surface, an opposing second surface, and a thickness extending therebetween. Providing a glass plate having, forming a groove by bringing a laser into contact with the glass plate along a predetermined path on the first surface, and a height of about 15% or less of the thickness of the glass plate Separating the glass sheet into two or more portions along the groove to form a glass article including at least one side edge including a chamfer having a thickness.

  Now, with reference to FIGS. 10A-10C, consider a method for making the glass articles of FIGS. 4, 6A and 6B. A glass plate 400 having a first surface, an opposing second surface, and a thickness extending therebetween, and at least one side edge can be provided. The first or second surface of the glass plate can be brought into contact with the laser, for example, by moving the laser along a predetermined path 470 represented by a dashed line on the surface of the fixed glass plate. Alternatively, the laser may be fixed and the glass plate can be moved along this predetermined path. As shown, the predetermined path 470 can be a straight line substantially perpendicular to at least one adjacent side edge 475, although other predetermined paths including non-linear paths are envisioned. Further, two or more predetermined paths can be followed on the surface to form more complex shapes and / or to separate the glass plate 400 into more than two parts. Contact with a laser, eg, an ultrashort pulse laser, can include a single laser pulse along a predetermined path, or multiple pulses can be used to increase the depth and / or width of the laser ablation region. it can. The pulses can have a duration of, for example, less than 1 second, for example, can have a duration of less than 1 nanosecond, or less than 1 picosecond. Non-limiting exemplary methods and lasers suitable for laser ablation and laser cutting of glass are described, for example, in U.S. Patent Application Nos. 14/145525, 14/530457, 14/535800, and 14/535754. No. 14/530379, No. 14/529801, No. 14/529520, No. 14 / 529,697, No. 14 / 536,094, No. 14 / 530,410 and No. 14/530244, and International Application No. PCT / EP 14/055364, PCT / US15 / 130019, and PCT / US15 / 13026, all of which are hereby incorporated by reference in their entirety.

  By irradiating the glass plate 400 with a laser along a predetermined path 470, a laser ablation region modified by a high energy density laser through a nonlinear effect can be created. By scanning over a predetermined path, a thin defect line 480 having a width W that defines the shape to be separated in a subsequent step can be created. As shown in FIG. 10A, the defect line 480 can have any desired optical properties and / or any width W suitable for obtaining a separate or split section. In some embodiments, the width W can range from about 1 micrometer to about 10 micrometers, such as from about 2 micrometers to about 9 micrometers, from about 3 micrometers to about 8 micrometers, about 4 micrometers. Can range from micrometer to about 7 micrometers, or from about 5 micrometers to about 6 micrometers, including all ranges and subranges therebetween. Referring to FIG. 10C, the laser can modify the glass plate along the predetermined path to any desired depth to create a laser ablation region having a thickness t1. Further, the laser can create a plurality of tomographic lines that extend in a substantially vertical direction along a predetermined path 470 from the first surface to the second surface. Thus, this predetermined path and / or defect line may depict the desired shape, and vertical fault lines along the defect line may be separated by crack propagation or any other mechanical or thermal separation technique. A path with minimum resistance can be established. According to some embodiments, the laser does not change or does not substantially change the total thickness T of the glass sheet at the side edges.

  Once the defect line 480 is created, separation can occur by applying manual and / or thermal stress on or around the defect line. Manual or mechanical stress, or pressure, can be applied along the defect line, for example, by applying an amount sufficient to create tension on a vertical fault line. Thermal stress can be applied using any suitable heat source that creates a stress zone on or around the defect line, thereby tensioning the vertical fault line and inducing partial or complete natural separation of the glass sheet. Can do. The methods used to separate the glass plates can be performed singly or in combination, and parameters relating to the separation method, e.g. force, temperature, etc., are various processing parameters developed around the laser, e.g. It can be changed according to the laser scanning speed, laser power, pulse width, repetition rate, pulse time, and the like.

  The glass plate 400 can thus be separated into two or more parts, and two parts 485, 490 are shown in FIG. 10B. Referring to portion 485, the glass portion can have a length L and side edges 415. The side edge 415 can include a laser ablation region 425 having a width w1. The width w1 of the laser ablation region may vary depending on, for example, the width W of the defect line and / or the separation method. In some embodiments, although not shown, for example, if substantially all of the defect lines are incorporated into the side edge 415 as the laser ablation region 425, w1≈W. In a further embodiment, for example, if a portion of the defect line constitutes the laser ablation region 425 of the side edge 415, w1 <W. In yet another embodiment, as shown, for example, 2 × w 1 ≈W for a cleaving along substantially the center of the defect line.

  A perspective view of a portion of the resulting glass article 500 (485) is shown in FIG. 10C and has a side edge 515 having a laser ablation region 525 as described above with respect to FIG. The laser ablation region 525 has a thickness t1 that extends partially along the entire thickness T of the glass article and a length that partially extends along the entire length L of the glass article, although the full length is not shown. And a width w1. In some embodiments, the described method can be used to create two glass articles having substantially identical side edges 515.

  This specification also discloses a method of forming the glass article of FIG. 9A, but is not shown in the drawing. The glass article of FIG. 9A can be prepared, for example, according to the procedure outlined above with respect to FIGS. 10A and 10B. However, in contrast to laser ablation methods that do not substantially change the thickness T of the glass article at the side edges, the method for forming the glass article of FIG. 9A creates a chamfer 360 at the side edge 315 of the glass article. Includes steps. Accordingly, by bringing the laser into contact with the surface of the glass plate along a predetermined path, it is possible to generate a cut or groove along the predetermined path. Similar to the defect line of FIG. 10A, this groove can have a width, and with reference to FIG. 9A, can penetrate to a depth sufficient to form a chamfer having a width w2 and a height h2.

Suitable lasers for cutting or grooving the glass plate include, for example, CO ₂ lasers, UV lasers, and infrared lasers operating at wavelengths greater than about 3 micrometers. Such lasers are described, for example, in U.S. Application Nos. 14/145525, 14/530457, 14/535800, 14/535754, 14/530379, 14/529801, 14/529520, Nos. 14/529797, 14 / 536,09 / 14/530410, and 14/530244, and international applications PCT / EP14 / 055364, PCT / US15 / 130019, and PCT / US15 /. No. 13026, all of which are hereby incorporated by reference in their entirety. Suitable cutting techniques include, for example, a CO ₂ laser scribing technique that utilizes a CO ₂ laser to rapidly heat the glass to a temperature at, near, or above the glass strain point. be able to. The rapid laser heating can be followed by a rapid cooling process using, for example, a water jet or a water mist jet. The rapid heating and quenching processes can produce a tensile stress (σ) that can be predicted by the following equation in the glass plate.

In this equation, α is the coefficient of thermal expansion, E is the Young's modulus, and ΔT is the temperature drop from the laser beam and cooling jet quench cycle. The tensile stresses that can be generated using this process for display glasses can in some cases range up to about 100 MPa.

After laser scribing process, such as mechanical separation (cleaving), or CO ₂ laser by separating step, it is possible to continue the separation by subsequent laser. In some embodiments, scribe and break technology can be employed. Since the cleaving stress can be directly correlated with the crack depth, in some embodiments, the grooves applied to the glass surface can have a depth of at least about 10% of the thickness of the glass, for example, The depth may be greater than about 15% of the glass thickness, or greater than about 20%, for example greater than about 25% of the glass thickness, or greater than about 30%. However, when laser cutting a glass plate, conflicting considerations should be balanced between ease of cleaving the glass plate and minimizing the chamfer height in the resulting glass article. . Another consideration when mechanically separating the glass plates is to minimize the formation of twist hackles, which can be caused by tensile stress applied to the cuts or grooves. The twist hackles can greatly affect the coupling efficiency of the light guide plates, as shown in Table II above. Thus, according to various embodiments, the glass light guides disclosed herein may include twist hackles or may be substantially free of twist hackles.

  According to various embodiments, the first surface and / or the second surface of the glass article may be patterned with a plurality of light extraction features. As used herein, the term “patterned” refers to any place where a plurality of elements and / or functions can be, for example, random or planned, repetitive or non-repetitive. It is intended to mean that it is present on the surface of a glass article in a given pattern or design. For example, in the case of a light extraction function unit, such a function unit may be distributed on the second surface as a texture function unit constituting a rough surface, for example.

In various embodiments, the light extraction features present on the first surface and / or the second surface of the glass article may include light scattering locations. For example, the first surface of the glass article may be textured, etched, coated, damaged, and / or roughened to produce a light extraction feature. Non-limiting examples of such methods, for example, be laser damage processing surfaces, that acid etching the surface, and the like to coat the surface with TiO _2. In certain embodiments, a laser can be used both to perforate the glass plate and to damage process the first surface and / or the second surface to create a light extraction feature. According to various embodiments, these extraction features may be patterned to a suitable depth to produce a substantially uniform illumination. This light extraction function part may cause surface scattering and / or volume scattering of light depending on the depth of these function parts on the glass surface. The optical characteristics of these functional units can be controlled by, for example, processing parameters used when generating these extraction functional units.

  The glass article can be produced according to any method known in the art, such as the method disclosed in co-pending and co-pending International Patent Application No. PCT / US2013 / 063622, which is incorporated herein by reference in its entirety. It may be processed to create an extraction function. For example, the glass plate may be ground and / or polished to achieve a desired thickness and / or desired surface quality. This glass may then optionally be cleaned and / or the surface of the glass to be etched may undergo a process to remove contaminants, such as exposing the surface to ozone.

  The glass plate may be chemically strengthened by, for example, ion exchange. During the ion exchange process, ions in the glass plate at or near the surface of the glass plate may be exchanged with larger metal ions, for example from a salt bath. The incorporation of larger ions into the glass can strengthen the glass plate by creating a compressive stress in the region near the surface. In order to balance the compressive stress, a corresponding tensile stress can be generated in the central region of the glass sheet.

The ion exchange may be performed, for example, by immersing a glass plate in a molten salt bath for a predetermined time. Exemplary salt baths include, but are not limited to, KNO ₃ , LiNO ₃ , NaNO ₃ , RbNO ₃ , and combinations thereof. The temperature of the molten salt bath and the processing time can be varied. It is within the ability of one skilled in the art to determine this time and temperature according to the desired application. As a non-limiting example, the temperature of the molten salt bath can range from about 400 ° C. to about 800 ° C., such as about 400 ° C. to about 500 ° C., and the predetermined time can be about 4 hours to about 10 hours, etc. Other temperature and time combinations are envisioned, although it can range from about 4 hours to about 24 hours. As a non-limiting example, the glass can be submerged in a KNO ₃ bath, for example, at about 450 ° C. for about 6 hours to obtain a K-rich layer that imparts surface compressive stress.

The surface to be etched is, as a non-limiting example, in an acid bath such as a mixture of glacial acetic acid (GAA) and ammonium fluoride (NH ₄ F), for example in a ratio ranging from about 1: 1 to about 9: 1. May be exposed. The etching time may range from, for example, about 30 seconds to about 15 minutes, and this etching may be performed at room temperature or at an elevated temperature. Processing parameters such as acid concentration, acid ratio, temperature, and / or time may affect the size, shape, and distribution of the resulting extraction feature. It is within the abilities of those skilled in the art to vary these parameters to obtain the desired surface extraction function.

  As used herein, the term “optically coupled” means that a light source is located at the edge of the glass article to direct light to the light guide. Is intended. When light is injected into a glass article, such as a glass light guide plate, according to certain embodiments, this light is totally reflected until it strikes a light extraction feature on the first surface or the second surface. (TIR) traps in the light guide and bounces back. As used herein, the term “light emitting surface” is intended to mean a surface from which light is emitted from a light guide plate toward an observer. For example, the first surface or the second surface can be a light emitting surface. Similarly, the term “light entrance surface” is intended to mean a surface coupled to a light source, eg, an LED, so that light enters the light guide. For example, the side edge of the light guide plate may be a light incident surface.

  The glass articles and glass light guides disclosed herein are used in a variety of display devices, including but not limited to LCDs or other displays used in the television industry, advertising industry, automotive industry, and other industries. May be. A conventional backlight unit used in an LCD may include various components. One or more light sources may be used, such as light emitting diodes (LEDs) or cold cathode fluorescent tubes (CCFLs). Conventional LCDs may employ LEDs or CCFLs packaged with color conversion phosphors to generate white light. According to various aspects of the present disclosure, a display device employing the glass article of the present disclosure emits at least one that emits blue light (ultraviolet light, about 100 to 400 nm), such as near ultraviolet light (about 300 to about 400 nm). May include two light sources. The light guide plates and devices disclosed herein may be used in any suitable lighting application such as, but not limited to, a lighting fixture.

  It will be appreciated that the various disclosed embodiments may be accompanied by specific features, elements or steps described in connection with that particular embodiment. In addition, although a particular feature, element, or step is described in connection with a particular embodiment, it may be interchanged or combined with another embodiment in various unshown combinations or variations You will see that there is.

  Also, as used herein, a noun refers to “at least one” subject and should not be limited to “one” subject unless specifically directed to the contrary. It should be understood that there is not. Thus, for example, reference to “a light source” includes examples having two or more such light sources unless the context clearly indicates otherwise. Similarly, “plurality” is intended to mean “two or more”. Thus, a “plurality of fault lines” includes two or more such fault lines, such as three or more such fault lines.

  As used herein, a range may be expressed as from “about” one particular value and / or to “about” another particular value. When such a range is expressed, an example includes from the one particular value and / or to the other particular value. Similarly, when a value is expressed as an approximation using the antecedent “about,” it will be seen that that particular value exhibits another value. Furthermore, it will be appreciated that the endpoints of each of these ranges are significant both when associated with the other endpoint and when unrelated to the other endpoint.

  As used herein, the terms “substantive”, “substantially” and variations thereof refer to an described feature being equal to or approximately equal to a value or description. Is intended. For example, a “substantially planar” surface is intended to mean a planar or nearly planar surface.

  Unless otherwise stated, any method described herein is in no way intended to be construed as requiring that the steps be performed in a specific order. Thus, if a method claim does not actually describe the order in which the steps are to be followed or specifically stated in the claim or specification that the steps should be limited to a particular order The case is not intended to imply any particular order.

  Although various features, elements or steps of particular embodiments may be disclosed using the transitional phrase “comprising”, they may be disclosed as “consisting of” or “substantially from” It should be understood that other embodiments are suggested, including embodiments that may be described using the transitional phrase “consisting essentially of”. Thus, for example, another embodiment suggested for a method comprising A, B, and C is an embodiment where the method consists of A, B, and C, and the method consists of A, B, and C. And substantially constructed embodiments.

  It will be apparent to those skilled in the art that various modifications and variations can be made to the present disclosure without departing from the spirit and scope of the disclosure. Since modifications, combinations, subcombinations and changes in the embodiments of the present disclosure that incorporate the spirit and gist of the present disclosure may occur to those skilled in the art, the present disclosure includes the appended claims and their equivalents. It should be construed to include everything within the scope of the object.

  Hereinafter, preferable embodiments of the present invention will be described in terms of items.

Embodiment 1
A glass article,
A first surface, an opposite second surface, and a thickness extending between the first surface and the second surface;
A glass article comprising at least one side edge comprising a laser ablation region having a thickness of about 35% or less of the thickness of the glass article.

Embodiment 2
2. The glass article of embodiment 1, wherein the thickness of the laser ablation region is about 20% or less of the thickness of the article.

Embodiment 3
The glass article of embodiment 1 or 2, wherein a scattering parameter of a light incident surface of the laser ablation region is less than about 0.2.

Embodiment 4
4. The glass article of any one of embodiments 1 to 3, further comprising a non-laser ablation region that includes a light incident surface having a scattering parameter less than about 0.1.

Embodiment 5
Embodiment 5. The glass article according to any one of embodiments 1-4, wherein the thickness of the glass article ranges from about 0.3 mm to about 3 mm.

Embodiment 6
6. The glass article according to any one of Embodiments 1 to 5, wherein the glass article is a light guide plate.

Embodiment 7
A display device including the glass article according to any one of the first to sixth embodiments.

Embodiment 8
8. The display device of embodiment 7, further comprising a light source optically coupled to the at least one side edge of the glass article.

Embodiment 9
The display device according to embodiment 8, wherein the light source is a light emitting diode.

Embodiment 10
9. The embodiment of embodiment 8, wherein the light source is disposed between the first surface and the second surface, or an edge of the light source is aligned with the first surface or the second surface. Display device.

Embodiment 11
9. The display device of embodiment 8, wherein the light source is coupled to the at least one side edge of the glass article at a location in close proximity to a non-laser ablation region.

Embodiment 12
At least one disposed on the first surface of the glass article, on the second surface of the glass article, or on both the first surface and the second surface of the glass article; The display device according to embodiment 7, further including a reflector.

Embodiment 13
A glass article,
A first surface, an opposite second surface, and a thickness extending between the first surface and the second surface;
At least one side edge including a chamfer adjacent to the first surface or the second surface, the chamfer having a height of about 15% or less of the thickness of the glass article. Glass article including two side edges.

Embodiment 14
The glass article according to embodiment 13, wherein the chamfered part is a laser cut chamfered part.

Embodiment 15
The glass article according to embodiment 13 or 14, wherein the at least one side edge includes only one chamfer.

Embodiment 16
The glass article according to any one of embodiments 13 to 15, wherein a scattering parameter of a light incident surface of the chamfered portion is less than about 0.1.

Embodiment 17
Embodiment 17. The glass article of any one of embodiments 13 to 16, further comprising a non-chamfered region comprising a light incident surface having a scattering parameter less than about 0.1.

Embodiment 18
The glass article of embodiment 17, wherein the non-chamfered region includes a twisted hackle pattern that traverses at least a portion of the thickness of the glass article.

Embodiment 19
The glass article according to embodiment 17, wherein the non-chamfered region does not include a twisted hackle pattern.

Embodiment 20.
Embodiment 17. The glass article according to any one of embodiments 13 to 16, wherein the thickness of the glass article ranges from about 0.3 mm to about 3 mm.

Embodiment 21.
The glass article according to any one of Embodiments 13 to 16, wherein the glass article is a light guide plate.

Embodiment 22
A display device comprising the glass article according to any one of embodiments 13 to 21.

Embodiment 23
Embodiment 23. The display device of embodiment 22, further comprising a light source optically coupled to the at least one side edge of the glass article.

Embodiment 24.
The display device according to embodiment 23, wherein the light source is a light emitting diode.

Embodiment 25
24. The display device of embodiment 23, wherein the laser cut chamfer is adjacent to the first surface, and an edge of the light source is aligned with the second surface.

Embodiment 26.
At least one disposed on the first surface of the glass article, on the second surface of the glass article, or on both the first surface and the second surface of the glass article; The display device of embodiment 22, further comprising a reflector.

Embodiment 27.
A method for producing a glass article, comprising:
Providing a glass plate having a first surface, an opposite second surface, and a thickness extending between the first surface and the second surface;
Forming a defect line by bringing a laser into contact with the glass plate along a predetermined path on the first surface;
The glass plate is divided into two or more portions along the defect line to form a glass article including at least one side edge including a laser ablation region having a thickness of about 35% or less of the thickness of the glass plate. Separating.

Embodiment 28.
28. The method of embodiment 27, wherein the laser is selected from an ultrashort pulse laser.

Embodiment 29.
The step of forming the defect line includes generating a laser ablation hole in the glass plate to a depth of about 35% or less of the thickness of the glass plate, and the second surface from the first surface of the glass plate. 29. A method according to embodiment 27 or 28, comprising optionally forming a fault line extending in a direction substantially perpendicular to the surface.

Embodiment 30.
30. The embodiment of any one of embodiments 27 to 29, wherein separating the glass sheet into two or more parts includes applying mechanical or thermal stress on or around the defect line. Method.

Embodiment 31.
A method for producing a glass article, comprising:
Providing a glass plate having a first surface, an opposite second surface, and a thickness extending between the first surface and the second surface;
Forming a groove by bringing a laser into contact with the glass plate along a predetermined path on the first surface;
Separating the glass plate into two or more parts along the groove to form a glass article including at least one side edge including a chamfer having a height of about 15% or less of the thickness of the glass plate Comprising the steps of:

Embodiment 32.
32. The method of embodiment 31, wherein the laser is selected from a CO ₂ laser, a UV laser, and an infrared laser operating at a wavelength greater than about 3 micrometers.

Embodiment 33.
32. The method of embodiment 31, wherein separating the glass sheet into two or more parts includes applying mechanical or thermal stress on or around the groove.

100, 200, 300, 500 Glass article 105, 205, 305 First surface 110, 210, 310 Second surface 115, 215, 315, 415, 515 Side edge 120, 360 Chamfer 140, 240 Light source 150 Reflector 225, 425, 525 Laser ablation region 235 Non-laser ablation region 230 Multiple laser ablation holes or damage marks 245 First reflector 250 Second reflector 360 Chamfer region 365 Twist hackle 400 Glass plate 470 Predetermined path 475 Adjacent side Edge 480 Defect line 485, 490 Glass plate portion T Glass article thickness t1 Laser ablation region thickness t2 Non-laser ablation region thickness H Light source height h Chamfered portion 120 height h2 Chamfered portion 360 height D Source and the side edge of the gap width L Length W Width w2 width of the chamfered portion 360 having a width w1 laser ablation region of the defect line

Claims (12)

A glass article,
A first surface, an opposite second surface, and a thickness extending between the first surface and the second surface;
A glass article comprising at least one side edge comprising a laser ablation region having a thickness of about 35% or less of the thickness of the glass article.   The glass article of claim 1, wherein the thickness of the laser ablation region is no more than about 20% of the thickness of the article, and the thickness of the glass article ranges from about 0.3 mm to about 3 mm.   The scattering parameter of the light incident surface of the laser ablation region is less than about 0.2, further comprising a non-laser ablation region including a light incident surface having a scattering parameter of less than about 0.1. Glass articles. A glass article,
A first surface, an opposite second surface, and a thickness extending between the first surface and the second surface;
At least one side edge including a chamfer adjacent to the first surface or the second surface, the chamfer having a height of about 15% or less of the thickness of the glass article. Glass article including two side edges.   The glass article according to claim 4, wherein the chamfered part is a laser-cut chamfered part.   The glass according to claim 4 or 5, further comprising a non-chamfered region including a light incident surface having a light incident surface having a scattering parameter less than about 0.1, wherein the light incident surface has a scattering parameter less than about 0.1. Goods.   The glass article according to claim 6, wherein the non-chamfered area includes a twist hackle pattern that traverses at least a portion of the thickness of the glass article, and the non-chamfered area does not include a twisted hackle pattern.   The glass article according to any one of claims 1 to 7, wherein the glass article is a light guide plate.   A display device comprising the glass article according to claim 1. A method for producing a glass article, comprising:
Providing a glass plate having a first surface, an opposing second surface, and a thickness extending between the first surface and the second surface;
Bringing a laser into contact with the glass plate along a predetermined path on the first surface to form a defect line;
The glass plate is divided into two or more portions along the defect line to form a glass article including at least one side edge including a laser ablation region having a thickness of about 35% or less of the thickness of the glass plate. Separating.   The step of forming the defect line includes generating laser ablation holes in the glass plate to a depth of about 35% or less of the thickness of the glass plate, and the second surface from the first surface of the glass plate. And optionally forming a fault line extending in a direction substantially perpendicular to the surface.   12. A method according to claim 10 or 11, wherein the step of separating the glass sheet into two or more parts comprises applying mechanical or thermal stress on or around the defect line.

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