Low stored tensile energy cutting glass and preferential crack propagation glass

Abstract

A glass substrate includes a first position in which a tensile stress of the glass substrate is insufficient to cause the glass substrate to shatter into small fragments upon the glass substrate breaking, and a second position in which the glass substrate is bent relative to the first position and in which a tensile stress of the glass substrate is sufficient to cause the glass substrate to shatter into small fragments upon the glass substrate breaking. The glass substrate can include a first surface and a second surface. In the first position, the first surface and the second surface of the glass substrate can be planar. In the second position, the first surface and the second surface of the glass substrate can be planar. The small fragments can generally be cuboid. In the second position, the glass substrate can be uniaxially bent along a bend axis of the glass substrate.

Description

[0001] Cross-references to related applications

[0002] This application is a divisional application of the invention patent application with application number 201980083292.0.

[0003] This application claims the benefit of priority to U.S. Provisional Application Serial No. 62 / 770,310, filed November 21, 2018, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0004] This disclosure generally relates to a glass substrate, including a reinforced glass substrate. More specifically, this disclosure relates to a glass substrate that has insufficient tensile stress in its natural state, thereby causing a desired degree of fragmentation (such as cutting) upon fracture, but has sufficient tensile energy to cause the desired degree of fragmentation upon fracture when a bending force is applied to the glass substrate. Background Technology

[0005] Due to surface defects, the mechanical strength of the raw glass substrate is within the range of MPa. That mechanical strength is suboptimal. The suboptimal mechanical strength of the raw glass substrate makes it unsuitable for use as a display and cover glass for consumer electronics devices such as televisions, telephones, and entertainment devices.

[0006] To suit such applications, the original glass substrate is sometimes mechanically strengthened, thus increasing its abrasion resistance. This mechanical strengthening is achieved by forming a layer on the surface of the glass under pressure. This layer is sometimes referred to as a "compressive stress layer" or a surface layer with "compressive stress."

[0007] The stress in the central region of the glass substrate balances the compressive stress in the compressive stress layer. Specifically, the interior of the glass substrate is under tensile stress. The tensile stress within the glass substrate balances the compressive stress in the glass compressive stress layer. Conceptually, the interior of the glass attempts to pull itself together (tensile stress), while each surface layer of the glass attempts to push itself apart.

[0008] Compressive stress at the surface layer of a glass substrate mechanically strengthens the glass substrate, thereby reducing the likelihood of glass substrate fracture (crack nucleation or other defects) and crack growth. The higher the degree of compressive stress, the greater the mechanical strength of the glass substrate. The depth of the compressive stress layer also affects the degree of mechanical strengthening, with the degree of mechanical strengthening increasing as the depth of the compressive stress layer increases. Thus, for mechanical strength purposes, it is advantageous to have a relatively high degree of compressive stress and a relatively deep depth of compression (or compressive stress). Generally, a high degree of compressive stress reduces the nucleation and growth of shallow scratches, and a deep depth of compression aids in drop test performance and prevents internal cracks from penetrating to the surface.

[0009] There are several common methods of applying compressive stress to the surface of an original glass substrate. One process uses heat, and is called "thermal tempering." Another process uses chemical composition, and is called "ion exchange" or "chemical tempering." In addition, a glass substrate can be incorporated into a glass laminate, which includes multiple different glasses, each having a different coefficient of thermal expansion, and the difference in the coefficients of thermal expansion generates compressive stress at the surface layer of the glass substrate.

[0010] As described above, thermal tempering of glass can induce a compressive stress layer at the surface of a glass substrate. To thermally temper a glass substrate, the glass substrate is heated above the transition temperature of the glass. The heated glass substrate is then rapidly cooled ("quenched"). During cooling, the surface of the glass substrate cools (decreases in temperature) faster than the interior of the glass substrate. The interior of the glass substrate cools slower than the surface of the glass substrate because the thickness of the glass substrate insulates the interior and the glass has a relatively low thermal conductivity. The surface of the glass substrate that cools faster than the interior has a greater molar / specific volume (or lower density) than the surface that cools slower. Thus, a molar volume gradient is created from the surface of the glass substrate to the interior of the glass substrate. The molar volume gradient provides a compressive stress surface layer, and the compressive stress decreases from the surface to the interior.

[0011] Thermal tempering of glass is generally faster and less costly than ion exchange processes. Thermal tempering produces a deeper compressive stress than ion exchange processes, typically extending from 1 / 5 to 1 / 3 of the thickness of the glass. However, thermal tempering generally produces a lower surface compressive stress than ion exchange processes, typically producing a compressive stress of less than 100 MPa.

[0012] Because thermal tempering relies on creating a sufficient thermal gradient between the surface and the interior, the glass substrate must be thick enough to allow for a sufficient thermal gradient. Thus, thermal tempering is utilized to strengthen relatively thick (3 mm or more) monolithic glass substrates, such as those used as side and rear window glass for automobiles. For glass substrates having a thickness of 2 mm or less, such as those intended for consumer electronics display applications, thermal tempering is generally ineffective.

[0013] In addition to thermal tempering, as described above, chemically tempering (ion exchange) a glass substrate can induce a compressive stress on the surface of the glass substrate. As an example of a chemical tempering process, a glass substrate is placed in a molten salt bath, such as a bath of alkali metal ions. The glass substrate contains ions that can be exchanged with the metal ions in the molten salt bath. The ions in the glass substrate that leave the glass substrate (such as Na + or Li + ions) are smaller than the ions in the molten salt bath that enter the glass substrate (such as K+ions in a KNO3 molten bath; Rb + , Cs + , and Ag + ions are other example ions). Exchanging the glass substrate with a relatively smaller ion for a relatively larger ion results in a biaxial (x and y axis) compressive stress at the location of the ion exchange.

[0014] Ion exchange generally occurs below the glass transition temperature of the glass substrate. In addition, the temperature should be below the temperature at which the glass substrate releases ions to reduce the compressive stress induced by the larger exchanged ions (this phenomenon is known as stress relaxation). Suitable temperatures can range from about 250 °C to about 500 °C. The ion exchange process can take from 4 hours to 11 hours, depending on the magnitude of the compressive stress desired and the depth of the compressive stress layer.

[0015] Chemical tempering by ion exchange can produce a higher level of compressive stress (up to about 1000 MPa) than thermal tempering. In addition, chemical tempering produces a limited depth of the compressive stress layer (typically 40-80 pm) compared to thermal tempering. However, the limited depth makes chemical tempering more suitable than thermal tempering for relatively thin glass (2 mm or less). Chemical tempering is used to make glass substrates have sufficient mechanical strength for applications including aircraft windows and scratch-resistant displays for consumer electronics.

[0016] In one or more embodiments, a glass substrate can be mechanically tempered by utilizing a mismatch in the coefficient of thermal expansion between portions of the glass substrate to create a compressive stress region and a central region exhibiting tensile stress.

[0017] The residual stress profile - i.e., the balance between surface compressive stress and interior tensile stress - resulting from a thermal, chemical, or mechanical tempering process applied to a glass substrate affects how the glass substrate reacts when the glass substrate fractures. How the glass substrate reacts when the glass substrate fractures is a design consideration relevant to the application in which the glass substrate is used. Generally speaking, the glass substrate should react in a safe and controlled manner when the glass substrate fractures.

[0018] The manner in which a glass substrate reacts when it fractures includes the fragmentation behavior of the glass substrate after fracture. To date, the fragmentation behavior of glass has been a function of the tensile energy stored in the tempered glass substrate. One potentially desirable fragmentation behavior is to cause a crack in the glass substrate to not bifurcate - i.e., for one crack not to split into two separate cracks. The more tensile energy stored in the glass substrate, the more likely a crack in the glass substrate is to bifurcate. Thus, to reduce the likelihood of bifurcation, the glass substrate can be tempered such that the tensile energy is relatively low or insufficient to cause such bifurcation. As discussed, tensile stress attempts to pull the glass substrate together. Thus, if sufficiently forceful, this tensile stress pulls the surface of the glass substrate inward, causing a crack formed in the surface layer to bifurcate. However, the direction in which the crack propagates is unpredictable.

[0019] Another potentially desirable fragmentation behavior is to cause the glass substrate to fragment into small pieces (sometimes referred to as "dicing" or "dices" of glass). Preferably, the width and length of the pieces are approximately equal to the thickness of the glass substrate. The result is a cubical piece with 90 degree corners. Pieces with corners approximately 90 degrees are considered to be dull and thus less likely to cause harm. To cause the glass substrate to fragment into small dices in this manner when it fractures, the tempered glass substrate must have sufficient tensile energy stored.

[0020] Potential undesirable fragmentation behaviors include the glass substrate fragmenting into (a) long, sharp pieces or (b) powder when it fractures. If the tensile stress in the tempered glass is sufficient to cause bifurcation of the glass substrate when it fractures, but insufficient to cause the glass to fragment into small pieces, the tensile stress causes the glass substrate to split into large pieces and / or elongated pieces. Large pieces and / or elongated pieces tend to have sharp edges, which are unsafe. Furthermore, if the tensile stress in the tempered glass substrate is greater than the tensile stress that would cause the glass substrate to fragment into small dices, the tensile stress causes the glass substrate to powder when it fractures. Powdered glass substrates are also unsafe.

[0021] Thus, there is a problem that a glass substrate tempered according to a particular tempering process can not have sufficient tensile stress to cause the glass substrate to break into small enough pieces (such as small squares), which limits the potential applications of the glass substrate (i.e., the glass cannot be used for applications that require breaking into small pieces). This problem is particularly prevalent in relatively thin glass substrates (less than 1 mm thick) because such thin glass substrates are too thin for thermal tempering and even too thin for chemical tempering to impart sufficient stored tensile stress to cause the glass substrate to break into small pieces upon fracture. In addition, there is another problem that the direction of the cracking, branching, and breaking is generally unpredictable and uncontrollable. Finally, there is another problem that thermal tempering imparts insufficient compressive stress to the surface of the glass substrate that is useful for the glass substrate in certain applications. SUMMARY

[0022] The present disclosure overcomes the above problems by bending the glass to impart additional tensile and compressive stress to certain regions of the glass substrate. Such bending can be applied dynamically or can be applied in a static manner. In one or more embodiments, the glass is bent by cold bending. Bending the glass substrate imparts tensile stress to the glass substrate that cooperates with the stored tensile stress of the tempered glass substrate to cause the glass substrate to break into small pieces upon fracture. Imparting tensile stress by bending allows the tempered glass substrate to be used in applications that require the glass substrate to break into small pieces upon fracture, which the tempered glass substrate otherwise lacks sufficient tensile stress to do. Imparting tensile stress via bending is particularly useful for relatively thin glass (less than 1 mm in thickness), as previously described, in which the glass substrate is too thin for the tempering process to impart sufficient tensile stress to cause the glass substrate to break into small pieces. In addition, as will be shown, uniaxial bending of the glass substrate imparts directional tensile stress that directs the glass substrate to fracture in a direction parallel to the axis of the uniaxial bend. It is useful, particularly in consumer electronics devices having displays that use the glass substrate, to cause the crack to propagate in a particular direction, thus, to point the crack to the side of the device rather than up or down the length of the device. In addition, as will be explained, bending of the glass substrate adds compressive stress to the compressive stress already imparted to the surface layer of the glass substrate via tempering. The additional compressive stress added to the compressive stress layer induced via tempering via bending can allow the glass substrate to be used in applications that require a certain threshold compressive stress on a particular surface layer, but which the tempering alone cannot impart.

[0023] According to a first aspect of the disclosure, a glass substrate includes: a first position in which a tensile stress of the glass substrate is insufficient to cause the glass substrate to shatter into small pieces upon the glass substrate breaking; and a second position in which the glass substrate is bent relative to the first position, and in which a tensile stress of the glass substrate is sufficient to cause the glass substrate to shatter into small pieces upon the glass substrate breaking. In one embodiment, the glass substrate further includes a first surface and a second surface. In one embodiment, in the first position, the first surface and the second surface of the glass substrate are planar. In one embodiment, in the second position, the first surface and the second surface of the glass substrate are planar. In one embodiment, the small pieces are generally cubical. In one embodiment, in the second position, the glass substrate is uniaxially bent along a bend axis of the glass substrate. In one embodiment, in the second position, the glass substrate is biaxially bent along two bend axes of the glass substrate. In one embodiment, in the first position, the glass substrate is flatter than the glass substrate in the second position. In one embodiment, in the second position, the glass substrate is flatter than the glass substrate in the first position. In one embodiment, the glass substrate has a thickness of 2 mm or less.

[0024] According to a second aspect of the disclosure, a method of increasing a compressive stress at a layer of a glass substrate includes: providing or forming a glass substrate; applying a first compressive stress within a first layer from a first surface of the glass substrate and within a second layer from a second surface of the glass surface; and bending the glass substrate along an axis of the glass substrate to increase the compressive stress to the first compressive stress within the second layer. In one embodiment, applying the first compressive stress within the first layer and the second layer of the glass substrate includes thermally tempering the glass substrate. In one embodiment, applying the first compressive stress within the first layer and the second layer of the glass substrate includes chemically tempering the glass substrate. In one embodiment, applying the first compressive stress within the first layer and the second layer of the glass substrate includes mechanically tempering the glass substrate. In one embodiment, the second surface of the glass substrate is a top surface of the glass substrate.

[0025] According to a third aspect of the disclosure, a method of reducing the size of fragments into which a glass substrate shatters upon breakage of the glass substrate includes: providing or forming a glass substrate that shatters into fragments having a first size upon breakage of the glass substrate; and bending the glass substrate to a second position and holding the glass substrate in the second position such that the glass substrate shatters into fragments having a second size upon breakage of the glass substrate; wherein the fragments having the second size are smaller than the fragments having the first size. In one embodiment, forming the glass substrate includes forming a glass substrate having a thickness of 2 mm or less. In one embodiment, bending the glass substrate includes biaxial bending of the glass substrate. In one embodiment, upon breakage of the glass substrate, the glass substrate shatters in the second position into fragments that form an in-plane isotropic fracture pattern. In one embodiment, bending the glass substrate includes uniaxial bending of the glass substrate along a bending axis of the glass substrate. In one embodiment, forming the glass substrate includes forming a glass substrate having a first surface that is flat. In one embodiment, forming the glass substrate includes forming a glass substrate having a first surface that is curved. In one embodiment, bending the glass substrate to the second position includes bending the glass substrate such that the first surface is less curved in the second position than in the first position. In one embodiment, bending the glass substrate and holding the glass substrate in the second position is achieved by a structural component of a product that utilizes the glass substrate at an ambient temperature.

[0026] According to a fourth aspect of the disclosure, a product includes: a glass substrate having a first position, wherein a tensile energy of the glass substrate is insufficient to cause the glass substrate to shatter into small fragments upon breakage of the glass substrate; and a component that bends the glass substrate from its first position to a second position, wherein a tensile energy of the glass substrate is sufficient to cause the glass substrate to shatter into small fragments upon breakage of the glass substrate. In one embodiment, the product is a consumer electronic device configured to be worn on a person's wrist. In one embodiment, the product is safety glass. In one embodiment, the glass substrate has a first surface and a second surface. In one embodiment, in the second position, the first surface has a higher compressive stress than the second surface.

[0027] According to a fifth aspect of the disclosure, a consumer electronics device comprising: a glass substrate disposed over a display screen, the glass substrate having a length, and a width extending from a first side to a second side; and a means for bending the glass substrate along a bend axis from a first position to a second position bent relative to the first position, such that when the glass substrate is fractured at the second position, the fracture generally propagates toward the first side or the second side of the glass substrate; wherein the bend axis is generally parallel to the width of the glass substrate. In one embodiment, at the first position, the glass substrate has a first compressive stress layer extending from a first surface. In one embodiment, the means for bending the glass substrate to the second position increases the compressive stress within the first layer. In one embodiment, the means for bending the glass substrate compresses the glass substrate from the first position to the second position. In one embodiment, the means for bending the glass substrate is an adhesive layer. In one embodiment, the consumer electronics device is a smartphone, a tablet, or a watch.

[0028] Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art who practice the embodiments described herein, including the detailed description which follows and the claims which conclude. It is intended that all such additional features and advantages be included within this description, be within the scope of the embodiments described herein, and be protected by the following claims.

[0029] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide a framework or a description for understanding the attributes and features of the claims. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a perspective view of a glass substrate in a first position, the glass substrate having a thickness defined by a distance between a first surface and a second surface, a width extending from a first side to a second side, and a length;

[0031] Figure 2 is a front view of the glass substrate of Figure 1

[0032] Figure 3 is a close-up schematic view of the glass substrate of Figure 1 , showing a central region of tensile stress between a first compressive stress layer and a second compressive stress layer, the tensile and compressive stresses being imparted via tempering;

[0033] Figure 4 is a perspective view of the glass substrate of Figure 1 , showing a fracture in the glass substrate extending over the length of the glass substrate, and showing the glass substrate not shattered into pieces by the fracture;

[0034] Figure 5 is a perspective view of the glass substrate of Figure 1 bent along a bend axis from​Figure 1 perspective view of the glass substrate of

[0035] Figure 6 is a picture showing Figure 1 graph of stress distribution in the glass substrate of

[0036] Figure 7 is a picture showing Figure 5 after bending the glass substrate to the second position shown in Figure 5 and keeping the glass substrate in the second position shown in Figure 1 graph of stress distribution applied in the glass substrate of

[0037] Figure 8 is a graph showing Figure 1 the degree of fragmentation (expressed by the square stress integral ) of the glass substrate of

[0038] Figure 9 is a picture of the tempered glass substrate after breaking at the second position (bent) showing that the degree of fragmentation is higher (smaller fragments, more fragments) when the tensile stress added by bending (left half of the picture) to the tensile stress applied by tempering (right part of the picture - larger fragments, fewer fragments) is higher;

[0039] Figure 10 is a magnified view of the area of the picture of Figure 9

[0040] Figure 11 is a series of pictures of the tempered glass substrate after breaking at the second position (bent) showing that the degree of fragmentation is a function of the bending radius (the smaller the bending radius, the greater the tensile stress generated, resulting in a higher degree of fragmentation) and of the thickness of the glass substrate (the greater the thickness, the higher the degree of fragmentation);

[0041] Figure 12A is a perspective view of a glass substrate similar to Figure 1 but having a first surface and a second surface bent at the first position (no bending applied);

[0042] Figure 12B is a perspective view of the glass substrate of Figure 12A showing that the glass substrate breaks into fragments of a first size (large) when it breaks;

[0043] Figure 13A is a perspective view of a glass substrate (tempered) combined​Figure 12A A perspective view of a product (safety glass) with a glass substrate, showing the glass substrate bent along a bending axis to a second position such that the first and second surfaces are flat, and components of the product holding the glass substrate in the second position.

[0044] Figure 13B It is a combination Figure 12A glass substrate Figure 13A The perspective view of the product shows that the glass substrate breaks into second-sized fragments (small fragments) due to the additional tensile stress applied to a region of the glass substrate by bending it to a second position.

[0045] Figure 14A It is similar to Figure 1 A perspective view of a glass substrate (tempered) having a first surface and a second surface (without bending) flat in a first position.

[0046] Figure 14B yes Figure 14A A perspective view of a glass substrate, showing the glass substrate breaking into fragments of the first size (large) upon fracture;

[0047] Figure 15A It is a combination Figure 14A A perspective view of a product (watch) with a glass substrate, showing that the glass substrate has been bent to a second position along a dual axis of a first bending axis and a second bending axis, such that the first surface and the second surface are bent, and a component of the product that holds the glass substrate in the second position.

[0048] Figure 15B It is a combination Figure 14A glass substrate Figure 15A The perspective view of the product shows that the glass substrate breaks into second-sized fragments (small fragments) due to the additional tensile stress applied to a region of the glass substrate by bending it to a second position.

[0049] Figure 16 It is shown Figure 1 The glass substrate is in the state Figure 5 The orientation deviation OB of the fracture at the second (bending) position (i.e., the direction in which the crack is deflected to propagate) depends on both the tensile stress (central tension) applied via tempering and the tensile stress (bending stress) applied via bending.

[0050] Figure 17 It is a graphical representation of a dynamic fracture simulation performed on a computer to produce Figure 1 glass substrate in Figure 5 The second location of the fracture is visualized as a fragmentation, and the graph shows the propagation of the fracture, which is generally parallel to the bending axis (Y-axis).

[0051] Figure 18 is an exploded perspective view of a consumer electronic device incorporating a glass substrate similar to Figure 1 but having a first surface and a second surface (not yet curved) that are curved in a first position, and the glass substrate is disposed over a display screen;

[0052] Figure 19 is a perspective view of a consumer electronic device of Figure 18 showing components of the consumer electronic device that bend the glass substrate along a bend axis to a second position and hold the glass substrate in the second position in which the first surface and the second surface are flat;

[0053] Figure 20 is a front view of a cross-section of a consumer electronic device of Figure 18 when the glass substrate is in a second position (curved) in Figure 19 taken along line XX-XX of Figure 19 ;

[0054] Figure 21 is a top view of a consumer electronic device of Figure 19 showing a crack in the glass substrate propagating along a direction generally parallel to the bend axis toward the second side of the glass substrate;

[0055] Figure 22 is an exploded perspective view of a consumer electronic device incorporating a glass substrate similar to Figure 1 but having a first surface and a second surface (not yet curved) that are curved in a first position, and the glass substrate is disposed over a display screen having an adhesive layer between the glass substrate and the display screen;

[0056] Figure 23 is a perspective view of a consumer electronic device of Figure 22 with a portion of the back plate cut away to show an adhesive layer holding the glass substrate in a second position (curved);

[0057] Figure 24 shows a person holding various consumer electronic devices incorporating a glass substrate in a second position (curved) of Figure 5 such as a watch, a tablet, and a smartphone of Figure 1 ; and Figure 15A

[0058] Figure 25 is a perspective view of an automotive interior system including a glass substrate in a second position (curved). DETAILED DESCRIPTION

[0059] Reference is now made to Figure 1 and Figure 2 ​The glass substrate 10 includes a first surface 12 and a second surface 14. The first surface 12 and the second surface 14 are major surfaces of the glass substrate 10, i.e., the surfaces of the glass substrate 10 having the largest surface area. Side surfaces 16 connect the first surface 12 and the second surface 14. The glass substrate 10 has a thickness 18, and is defined as the maximum distance between the first surface 12 and the second surface 14. In the illustrated embodiment, the glass substrate 10 has a substantially constant thickness 18. The glass substrate 10 has a width 20, which is defined as the first maximum dimension of one of the first surface 12 or the second surface 14 that is orthogonal to the thickness 18. In the illustrated embodiment, the width 20 is thus the distance between a first side 22 and a second side 24 of the glass substrate 10 along the first surface 12. The glass substrate 10 has a length 26, which is defined as the second maximum dimension of one of the first surface 12 or the second surface 14 that is orthogonal to both the thickness 18 and the width 20.

[0060] As used herein, the term "glass substrate" 10 is used in its broadest sense to include any object that is wholly or partially made of glass. The glass substrate 10 includes laminates of glass and non-glass materials, laminates of glass and crystalline materials, and glass-ceramics (including amorphous and crystalline phases). The glass substrate 10 can be transparent or non-transparent. In one or more embodiments, the glass substrate 10 can include a colorant that provides a particular color. Suitable glass compositions that form the glass substrate 10 include soda-lime glass compositions, alumino-silicate glass compositions, borosilicate glass compositions, boro-alumino-silicate glass compositions, alkali-containing alumino-silicate glass compositions, alkali-containing borosilicate glass compositions, and alkali-containing boro-alumino-silicate glass compositions.

[0061] Unless otherwise indicated, the compositions of the glass substrates 10 disclosed herein are described in mole percent (mol%) based on an analysis of oxides.

[0062] In one or more embodiments, the glass composition can include Si02 in an amount from about 66 mol% to about 80 mol%, from about 67 mol% to about 80 mol%, from about 68 mol% to about 80 mol%, from about 69 mol% to about 80 mol%, from about 70 mol% to about 80 mol%, from about 72 mol% to about 80 mol%, from about 65 mol% to about 78 mol%, from about 65 mol% to about 76 mol%, from about 65 mol% to about 75 mol%, from about 65 mol% to about 74 mol%, from about 65 mol% to about 72 mol%, or from about 65 mol% to about 70 mol%, and all ranges and sub-ranges therebetween.

[0063] In one or more embodiments, the glass composition includes Al2O3 in an amount greater than about 4 mol%, or greater than about 5 mol%. In one or more embodiments, the glass composition includes Al2O3 in an amount from greater than about 7 mol% to about 15 mol%, from greater than about 7 mol% to about 14 mol%, from about 7 mol% to about 13 mol%, from about 4 mol% to about 12 mol%, from about 7 mol% to about 11 mol%, from about 8 mol% to about 15 mol%, from about 9 mol% to about 15 mol%, from about 10 mol% to about 15 mol%, from about 11 mol% to about 15 mol%, or from about 12 mol% to about 15 mol%, and all ranges and sub-ranges therebetween. In one or more embodiments, the upper limit of Al2O3 can be about 14 mol%, 14.2 mol%, 14.4 mol%, 14.6 mol%, or 14.8 mol%.

[0064] In one or more embodiments, the glass substrate 10 is described as an aluminosilicate glass substrate or includes an aluminosilicate glass composition. In such embodiments, the glass composition or substrate formed therefrom includes SiO2 and Al2O3, rather than a soda-lime silicate glass. In this regard, the glass composition or substrate formed therefrom includes Al2O3 in an amount of about 2 mol% or greater, about 2.25 mol% or greater, about 2.5 mol% or greater, about 2.75 mol% or greater, or about 3 mol% or greater.

[0065] In one or more embodiments, the glass composition includes B2O3 (e.g., about 0.01 mol% or greater). In one or more embodiments, the glass composition includes B2O3 in an amount from about 0 mol% to about 5 mol%, from about 0 mol% to about 4 mol%, from about 0 mol% to about 3 mol%, from about 0 mol% to about 2 mol%, from about 0 mol% to about 1 mol%, from about 0 mol% to about 0.5 mol%, from about 0.1 mol% to about 5 mol%, from about 0.1 mol% to about 4 mol%, from about 0.1 mol% to about 3 mol%, from about 0.1 mol% to about 2 mol%, from about 0.1 mol% to about 1 mol%, from about 0.1 mol% to about 0.5 mol%, and all ranges and sub-ranges therebetween. In one or more embodiments, the glass composition is substantially free of B2O3.

[0066] As used herein, the phrase "substantially free of" with respect to a component of a composition means that the component is not added to the composition during initial batching either actively or intentionally, but can be present as an impurity in an amount less than about 0.001 mol%.

[0067] In one or more embodiments, the glass composition optionally includes P2O5(e.g., about 0.01 mole% or greater). In one or more embodiments, the glass composition includes a non-zero amount of P2O5up to and including 2 mole%, 1.5 mole%, 1 mole%, or 0.5 mole%. In one or more embodiments, the glass composition is substantially free of P2O5.

[0068] In one or more embodiments, the glass composition can include a total amount of R2O (which is the total amount of alkali metal oxides such as Li2O, Na2O, K2O, Rb2O, and Cs2O) greater than or equal to about 8 mole%, greater than or equal to about 10 mole%, or greater than or equal to about 12 mole%. In some embodiments, the glass composition includes a total amount of R2O in a range from about 8 mole% to about 20 mole%, about 8 mole% to about 18 mole%, about 8 mole% to about 16 mole%, about 8 mole% to about 14 mole%, about 8 mole% to about 12 mole%, about 9 mole% to about 20 mole%, about 10 mole% to about 20 mole%, about 11 mole% to about 20 mole%, about 12 mole% to about 20 mole%, about 13 mole% to about 20 mole%, about 10 mole% to about 14 mole%, or 11 mole% to about 13 mole%, and all ranges and sub-ranges therebetween. In one or more embodiments, the glass composition can be substantially free of Rb2O, Cs2O, or both Rb2O and Cs2O. In one or more embodiments, the R2O can include only a total amount of Li2O, Na2O, and K2O. In one or more embodiments, the glass composition can include at least one alkali metal oxide selected from Li2O, Na2O, and K2O, wherein the alkali metal oxide is present in an amount greater than about 8 mole%.

[0069] In one or more embodiments, the glass composition includes Na2O in an amount greater than or equal to about 8 mole%, greater than or equal to about 10 mole%, or greater than or equal to about 12 mole%. In one or more embodiments, the composition includes Na2O in a range from 8 mole% to about 20 mole%, about 8 mole% to about 18 mole%, about 8 mole% to about 16 mole%, about 8 mole% to about 14 mole%, about 8 mole% to about 12 mole%, about 9 mole% to about 20 mole%, about 10 mole% to about 20 mole%, about 11 mole% to about 20 mole%, about 12 mole% to about 20 mole%, about 13 mole% to about 20 mole%, about 10 mole% to about 14 mole%, or 11 mole% to about 16 mole%, and all ranges and sub-ranges therebetween.

[0070] In one or more embodiments, the glass composition includes less than about 4 mol%, less than about 3 mol%, or less than about 1 mol% K2O. In some cases, the glass composition can include K2O in an amount ranging from about 0 mol% to about 4 mol%, about 0 mol% to about 3.5 mol%, about 0 mol% to about 3 mol%, about 0 mol% to about 2.5 mol%, about 0 mol% to about 2 mol%, about 0 mol% to about 1.5 mol%, about 0 mol% to about 1 mol%, about 0 mol% to about 0.5 mol, about 0 mol% to about 0.2 mol%, about 0 mol% to about 0.1 mol%, about 0.5 mol% to about 4 mol%, about 0.5 mol% to about 3.5 mol%, about 0.5 mol% to about 3 mol%, about 0.5 mol% to about 2.5 mol%, about 0.5 mol% to about 2 mol%, about 0.5 mol% to about 1.5 mol%, or about 0.5 mol% to about 1 mol%, and all ranges and sub-ranges therebetween. In one or more embodiments, the glass composition can be substantially free of K2O.

[0071] In one or more embodiments, the glass composition is substantially free of Li2O.

[0072] In one or more embodiments, the amount of Na2O in the composition can be greater than the amount of Li2O. In some cases, the amount of Na2O can be greater than the combined amount of Li2O and K2O. In one or more alternative embodiments, the amount of Li2O in the composition can be greater than the amount of Na2O or the combined amount of Na2O and K2O.

[0073] In one or more embodiments, the glass composition can include a total amount of RO (which is the total amount of alkaline earth metal oxides such as CaO, MgO, BaO, ZnO, and SrO) ranging from about 0 mol% to about 2 mol%. In some embodiments, the glass composition includes a non-zero amount of RO up to about 2 mol%. In one or more embodiments, the glass composition includes RO in an amount ranging from about 0 mol% to about 1.8 mol%, about 0 mol% to about 1.6 mol%, about 0 mol% to about 1.5 mol%, about 0 mol% to about 1.4 mol%, about 0 mol% to about 1.2 mol%, about 0 mol% to about 1 mol%, about 0 mol% to about 0.8 mol%, about 0 mol% to about 0.5 mol%, and all ranges and sub-ranges therebetween.

[0074] In one or more embodiments, the glass composition includes an amount of CaO less than about 1 mol%, less than about 0.8 mol%, or less than about 0.5 mol%. In one or more embodiments, the glass composition is substantially free of CaO.

[0075] In some embodiments, the glass composition includes MgO in an amount ranging from about 0 mol% to about 7 mol%, from about 0 mol% to about 6 mol%, from about 0 mol% to about 5 mol%, from about 0 mol% to about 4 mol%, from about 0.1 mol% to about 7 mol%, from about 0.1 mol% to about 6 mol%, from about 0.1 mol% to about 5 mol%, from about 0.1 mol% to about 4 mol%, from about 1 mol% to about 7 mol%, from about 2 mol% to about 6 mol%, or from about 3 mol% to about 6 mol%, and all ranges and sub-ranges therebetween.

[0076] In one or more embodiments, the glass composition includes Zr02in an amount equal to or less than about 0.2 mol%, less than about 0.18 mol%, less than about 0.16 mol%, less than about 0.15 mol%, less than about 0.14 mol%, or less than about 0.12 mol%. In one or more embodiments, the glass composition includes Zr02in a range from about 0.01 mol% to about 0.2 mol%, from about 0.01 mol% to about 0.18 mol%, from about 0.01 mol% to about 0.16 mol%, from about 0.01 mol% to about 0.15 mol%, from about 0.01 mol% to about 0.14 mol%, from about 0.01 mol% to about 0.12 mol%, or from about 0.01 mol% to about 0.10 mol%, and all ranges and sub-ranges therebetween.

[0077] In one or more embodiments, the glass composition includes Sn02in an amount equal to or less than about 0.2 mol%, less than about 0.18 mol%, less than about 0.16 mol%, less than about 0.15 mol%, less than about 0.14 mol%, or less than about 0.12 mol%. In one or more embodiments, the glass composition includes Sn02in a range from about 0.01 mol% to about 0.2 mol%, from about 0.01 mol% to about 0.18 mol%, from about 0.01 mol% to about 0.16 mol%, from about 0.01 mol% to about 0.15 mol%, from about 0.01 mol% to about 0.14 mol%, from about 0.01 mol% to about 0.12 mol%, or from about 0.01 mol% to about 0.10 mol%, and all ranges and sub-ranges therebetween.

[0078] In one or more embodiments, the glass composition can include oxides that impart color or tint to the glass substrate 10. In some embodiments, the glass composition includes oxides that prevent discoloration of the glass substrate 10 when exposed to ultraviolet radiation. Examples of such oxides include, but are not limited to, the following oxides: Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ce, W, and Mo.

[0079] In one or more embodiments, the glass composition includes Fe represented as Fe2O3, where Fe is present in an amount up to (and including) about 1 mol%. In some embodiments, the glass composition is substantially free of Fe. In one or more embodiments, the glass composition includes Fe2O3 in an amount equal to or less than about 0.2 mol%, less than about 0.18 mol%, less than about 0.16 mol%, less than about 0.15 mol%, less than about 0.14 mol%, or less than about 0.12 mol%. In one or more embodiments, the glass composition includes Fe2O3 in a range from about 0.01 mol% to about 0.2 mol%, from about 0.01 mol% to about 0.18 mol%, from about 0.01 mol% to about 0.16 mol%, from about 0.01 mol% to about 0.15 mol%, from about 0.01 mol% to about 0.14 mol%, from about 0.01 mol% to about 0.12 mol%, or from about 0.01 mol% to about 0.10 mol%, and all ranges and sub-ranges therebetween.

[0080] When the glass composition includes TiO2, TiO2may be present in an amount of about 5 mol% or less, about 2.5 mol% or less, about 2 mol% or less, or about 1 mol% or less. In one or more embodiments, the glass composition can be substantially free of TiO2.

[0081] Exemplary glass compositions include: SiO2in an amount in a range from about 65 mol% to about 75 mol%; AI2O3in an amount in a range from about 8 mol% to about 14 mol%; Na2O in an amount in a range from about 12 mol% to about 17 mol%; K2O in an amount in a range from about 0 mol% to about 0.2 mol%; and MgO in an amount in a range from about 1.5 mol% to about 6 mol%. Optionally, SnO2may be included in amounts otherwise disclosed herein.

[0082] The selected glass composition can be formed into the glass substrate 10 using any method capable of producing a temperable glass substrate 10. Exemplary methods capable of producing the glass substrate 10 include down-draw methods that form a sheet of the glass substrate 10. Down-draw methods include, but are not limited to, fusion draw and slot draw methods. Down-draw methods are used in the large-scale manufacture of flat glass substrates 10 such as display glasses and ion exchanged glasses (capable of chemical tempering). Fusion draw methods use a forming body having a channel for receiving a molten glass feedstock. The channel has a weir that opens at the top on both sides of the channel along the length of the channel. When the channel is filled with the molten material, the molten glass overflows the weir. Due to gravity, the molten glass flows down the outer surfaces of the isopipe. These outer surfaces extend downward and inward so that they join at an edge below the draw slot. The two flowing glass surfaces join at this edge to fuse and form a single flowing sheet. Fusion draw methods offer the advantage that neither outer surface of the resulting glass sheet comes into contact with any part of the apparatus since the two glass films flowing over the channel fuse together. Thus, the surface properties are not affected by such contact. The initially formed glass substrate 10 has no compressive stress layers at the first surface 12 and the second surface 14.

[0083] Referring now to Figure 3 The glass substrate 10 is then tempered, chemically tempered, or thermally tempered, or both chemically and thermally tempered, or otherwise tempered. After such tempering, the glass substrate 10 has a first layer 28 of compressive stress applied to the first surface 12 and extending through the thickness 18, referred to as the depth of compression (DOC) 30. The tempering additionally applies a second layer 32 of compressive stress to the second surface and extending through the thickness 18, referred to as the depth of compression (DOC) 34. The tempering further applies a tensile stress within a central region 36 between the first layer 28 and the second layer 32. This tensile stress is sometimes referred to as a “central tension.” The tensile stress within the central region 36 balances the compressive stress within the first layer 28 and the second layer 32.

[0084] In Figures 1-3 The glass substrate 10 is shown in an embodiment of the first position 38. In this embodiment of the first position 38, the first surface 12 and the second surface 14 of the glass substrate 10 are planar. In other words, the first surface 12 and the second surface 14 are flat. However, as discussed further below, the first surface 12 and the second surface 14 need not be flat in the first position 38.

[0085] Referring now to Figure 4This disclosure assumes that when the glass substrate 10 is in the first position 38, the tempering of the glass substrate 10 results in insufficient tensile energy at the central region 36 of the glass substrate 10 to cause the glass substrate 10 to shatter into fragments 40 of sufficiently small size upon fracture 42 for its intended application. In other words, when the glass substrate 10 fractures 42, it shatters into larger fragments 40 (with a larger surface area) compared to its surface area (length 26 × width 20) before fracture 42. The tensile stress is too low.

[0086] Now refer to Figure 5 The glass substrate 10 is in the second position 44. In the second position 44, the glass substrate 10 is bent relative to the first position 38. This is because the first surface 12 and the second surface 14 of the glass substrate 10 are bent relative to the first position 38. Figure 1 The first surface 12 and the second surface 14 of the glass substrate 10 are planar (i.e., flat), therefore the first surface 12 and the second surface 14 of the glass substrate 10 are not planar (i.e., not flat—the first surface 12 and the second surface 14 are now curved). In the illustrated embodiment, the glass substrate 10 is flatter in the first position 38 than in the second position 44. In the illustrated embodiment, the glass substrate 10 is uniaxially bent along the bending axis 46 of the glass substrate 10.

[0087] In one or more embodiments, the glass substrate 10 is uniaxially bent along the bending axis 46 by cold bending. As used herein, the term "cold bending" or "cold bending" refers to bending the glass substrate at a cold bending temperature below the glass softening point. Typically, the cold bending temperature is room temperature. The term "cold-bendable" refers to the ability of the glass substrate to bend cold. The cold-bending glass substrate is characterized by asymmetric surface compressive stress (e.g., between the first surface 12 and the second surface 14) between the first surface 12 and the second surface 14. Figure 5 (As shown). In one or more embodiments, the corresponding compressive stresses in the first surface 12 and the second surface 14 of the glass substrate are substantially equal before the cold bending process or before being cold bent. In one or more embodiments where the glass substrate is not strengthened, the first surface 12 and the second surface 14 do not exhibit considerable compressive stresses before cold bending. In one or more embodiments where the glass substrate is strengthened (as described herein), the first surface 12 and the second surface 14 exhibit substantially equal compressive stresses relative to each other before cold bending. In one or more embodiments, after cold bending, the compressive stress (CS) on the concave surface (e.g., the second surface 14) increases after cold bending, while the CS on the convex surface (e.g., the first surface 12) decreases after cold bending. In other words, the compressive stress on the concave surface (e.g., the second surface 14) is greater after cold bending than before cold bending.

[0088] As will be discussed, the bend of the glass substrate 10 affects the stress profile of the glass substrate 10 after tempering (the compressive and tensile stress profile throughout the glass substrate 10). Specifically, because the bend creates a uniaxial bend in a direction toward the second surface 14, the bend increases the compressive stress at the second layer 32 and decreases the compressive stress at the first layer 28. Further, by affecting the stress profile of the tempered glass substrate 10, the bend affects the degree of fragmentation experienced by the tempered glass substrate 10 upon breakage 42 (more small size fragments 40) by increasing the degree of fragmentation to more small size fragments 40.

[0089] The analytical model illustrates these points. For the analytical model, it can be assumed that the glass substrate 10 has a stress profile after tempering as shown in FIG. 4 based on the underlying assumption that the thickness 18 is 0.55 mm. The stress profile profiles the stress of the glass substrate 10 as a function of position through the thickness 18 of the glass substrate 10 after tempering. Negative stress values are compressive stresses, while positive stress values are tensile stresses. As noted above, the compressive stress extends from the first surface 12 through the DOC 30 of the first layer 28, and from the second surface 14 through the DOC 34 of the second layer 32. As noted above, the tensile stress extends within the central region 36 between the first compressive stress layer 28 and the second compressive stress layer 32. Figure 6

[0090] Next, the analytical model can explain the stress induced by the uniaxial bend of the glass substrate 10 along the bend axis 46 as a function of the z-axis position through the thickness 18 of the glass substrate 10 by a linear equation. The linear equation is:

[0091]

[0092] The variable z is the value of the z-axis position through the thickness t 18 of the glass substrate 10. The variable σ bendmax is the assigned value, and is the maximum bend stress at the first surface 12. If we again assume that the thickness t 18 of the glass substrate 10 is 0.55 mm, and the maximum bend stress σ bendmax applied to the glass substrate 10 is 137 MPa, then the results of the above linear equation can be plotted. This plot is shown in FIG. 5. Figure 7 ​The bending of the glass substrate 10 along the bending axis 46 is shown in the analysis model. In this analysis model, the bending along the bending axis 46 is the y-axis in the model. Thus, the bending stress is greatest along the y-axis. However, due to the Poisson's ratio effect, bending the glass substrate 10 along the y-axis will also induce stress along the x-axis, although the stress is less than the stress along the y-axis. Note that the bending stress from the first surface 12 to the middle of the thickness 18 of the glass substrate 10 is a tensile stress, which offsets the compressive stress created via tempering in the first layer 28, and increases the tensile stress created via tempering in the central region 36 from the middle of the thickness 18 to the center of the first layer 28. Further, note that the bending stress from the middle of the thickness 18 to the second surface 14 is a compressive stress, which offsets the tensile stress created via tempering from the middle of the thickness 18 toward the second layer 32, and increases the compressive stress created via tempering in the second layer 32.

[0093] Thus, the analysis model demonstrates a new method of increasing the compressive stress in a layer of the glass substrate 10 (either the first layer 28 or the second layer 32 depending on the direction of bending). As described above, the method includes forming a glass substrate 10. The method further includes applying a first compressive stress in the first layer 28 from the first surface 12 and a first compressive stress in the second layer 32 from the second surface 14 via tempering the glass substrate 10. The method then includes bending the tempered glass substrate 10 along the bending axis 46 of the glass substrate 10 in the direction of the second surface 14 to add compressive stress to the first compressive stress in the second layer 32. Conversely, if it is desired to add compressive stress to the first compressive stress in the first layer 28, the method would include bending the tempered glass substrate 10 along the bending axis 46 in the direction of the first surface 12. In one embodiment of the method, applying the first compressive stress in the first layer 28 and the second layer 32 of the glass substrate 10 includes thermally tempering the glass substrate 10. In one embodiment of the method, applying the first compressive stress in the first layer 28 and the second layer 32 of the glass substrate 10 includes chemically tempering the glass substrate 10. In embodiments of the method, the second surface 14 of the glass substrate 10 is a top surface of the glass substrate 10. This method of increasing the compressive stress at the first layer 28 or the second layer 32 of the glass substrate 10 is particularly beneficial when the glass substrate 10 has a relatively thin thickness 18 (e.g., 2 mm or less, 1.8 mm or less, 1.6 mm or less, 1.5 mm or less, 1.4 mm or less, 1.2 mm or less, 1 mm or less, or 0.75 mm or less, or 0.55 mm or less) because chemical tempering of such thin glass substrates 10 can not be able to apply the necessary compressive stress at the second layer 32.

[0094] Continuing with the model analysis, based on the following equations, the one-dimensional stress distribution of the glass substrate 10 after tempering and after bending can be calculated as a function of the z-axis position along the thickness t18 of the glass substrate 10:

[0095]

[0096] The variable σ(z) is the total stress as a function of the position z along the z-axis of the glass substrate 10, where the thickness t18 is [missing value]. CT This is the maximum tensile stress within the central region 36 of the glass substrate 10, as a result of tempering alone. As described above, the variable σ... bendmax It is the maximum bending stress at point 12 on the first surface.

[0097] Integrating the above equation with the sum of squares yields the square stress integral, which provides the relative degree of fragmentation of the glass substrate 10 at fracture 42. The equation is as follows:

[0098]

[0099] symbol This represents the square stress integral. The variable z... 1 and z 2 It is the root of the square stress integral function, corresponding to a depth DOC(z) from the layer. 1 ) to another depth of the layer DOC(z) 2 The z-axis position passing through the central region 36 of thickness t18. (e.g.) Figure 8 As shown, the square stress integral With the maximum bending stress σ bendmax The increase corresponds to a higher degree of fragmentation at fracture 42 (i.e., more fragments 40 and smaller fragments 40). In other words, even if tempering applies a relatively small amount of tensile stress (central tension) to the central region 36 (i.e., too low to fragment into small fragments 40 at fracture 42), bending will increase the tensile stress in the portion of the central region 36 away from the bending direction against the tensile stress already applied by tempering. The increased tensile stress causes the stress integral to square the value of the stress. The tensile stress increases, thereby increasing the degree of fragmentation upon fracture. Therefore, even if the tensile stress applied to the central region 36 of the glass substrate 10 via tempering is insufficient to cause the glass substrate 10 to shatter into small fragments 40 upon fracture 42, the additional tensile stress applied by bending the glass substrate 10 is sufficient to cause such a high degree of fragmentation.

[0100] Applicant has confirmed the analytical model through physical experiments. Applicant formed a glass substrate 10 having a thickness t18 of 0.7 mm. Applicant applied a tensile stress to the glass substrate 10 through chemical tempering. Specifically, Applicant ion exchanged the glass substrate 10 at 420°C for 5.5 hours. As a result, the glass substrate 10 had a maximum tensile stress (central tension) σ CT .

[0101] Applicant then applied a bending stress to the glass substrate 10 using a four-point bending apparatus. The middle two points of the bending apparatus were located 9 mm from the center of the glass substrate 10. The outer two points of the bending apparatus were located 18 mm from the center of the glass substrate 10. The apparatus applied a bending stress until the glass substrate 10 fractured 42. The bending stress that caused the glass substrate 10 to fracture 42 was about 480 MPa. In Figure 9 , a picture of the glass substrate 10 after fracture 42 is depicted showing a plot of the bending stress applied to the glass substrate 10 as a function of position along the width 20 of the glass substrate 10. Figure 10 The same content is shown, but zoomed in to show the regions where the bending stress was applied and where the bending stress was not applied. The drop in bending stress from about 480 MPa to zero is consistent with the picture of Figure 10 , and indicates that one of the middle two points of the four-point bending apparatus was applied to the glass substrate 10. The glass substrate 10 was subjected to a bending stress of about 480 MPa between the two middle points of the bending apparatus. The glass substrate 10 exhibited a high degree of fragmentation (small pieces 40) where the bending stress of about 480 MPa was applied to the glass substrate 10. In contrast, the glass substrate 10 exhibited a low degree of fragmentation (large pieces 40) where no bending stress was applied (approximately between the inner and outer points on each side of the apparatus), indicating that tempering alone was not sufficient to produce the tensile stress generated in the central region 36 to cause a high degree of fragmentation (small pieces 40) at fracture 42. The contrast indicates that the bending stress can increase the tensile stress required for the glass substrate 10 to exhibit a high degree of fragmentation at fracture 42 when tempering the glass substrate 10 does not increase the tensile stress enough to achieve a higher degree of fragmentation.

[0102] Reference is now made to Figure 11In another physical experiment, Applicants chemically tempered nine samples of glass substrates 10. The nine samples were grouped into three thicknesses 18, three samples each, having thicknesses of 0.4 mm, 0.55 mm, and 0.7 mm. The chemical tempering by ion exchange imparted a compressive stress of 825 MPa at the first and second layers 28, 32 of each sample glass substrate 10. The depth of compressive stress (DOC) of the layers was 42.5 μm. The resulting tensile stress was insufficient to cause the glass substrate 10 to shatter into small fragments 40 upon fracture 42. One glass substrate 10 of each thickness 18 was cylindrically (uniaxially) bent from the first position 38 to the second position 44 at constant radii of 250 mm, 500 mm, and 1000 mm, held at the second position 44 (bent), and then concave in the center until the glass substrate 10 fractured 42.

[0103] As shown in the pictures reproduced in Figure 11 , the more severe the bend (i.e., the smaller the bend radius), the smaller the fragments 40 upon fracture 42 of the glass substrate 10. For example, for the three samples having a thickness 18 of 0.4 mm, the glass substrate 10 subjected to a bend radius of 500 mm produced smaller fragments 40 upon fracture 42 than the glass substrate 10 subjected to a bend radius of 1000 mm. The glass substrate 10 subjected to a bend radius of 250 mm produced even smaller fragments 40 upon fracture 42 than the glass substrate 10 subjected to a bend radius of 500 mm. Thus, the more severe the bend imparted on the glass substrate 10 to change the glass substrate 10 from the first position 38 to the second position 44, the more likely the glass substrate 10 is to shatter into small fragments 40 upon fracture 42.

[0104] Furthermore, the pictures reproduced in Figure 11 also show that the thicker the thickness 18 of the glass substrate 10, the smaller the fragments 40 upon fracture 42 of the glass substrate 10. For example, for the three samples bent at a constant radius of 500 mm, the glass substrate 10 having a thickness 18 of 0.55 mm produced smaller fragments 40 upon fracture 42 than the glass substrate 10 having a thickness 18 of 0.4 mm. The glass substrate 10 having a thickness 18 of 0.7 mm produced even smaller fragments 40 upon fracture 42 than the glass substrate 10 having a thickness 18 of 0.55 mm. Thus, the thicker the thickness 18 of the glass substrate 10, the more likely the glass substrate 10 is to shatter into small fragments 40 upon fracture 42 for any given bend radius imparted on the glass substrate 10.

[0105] Referring now to Figures 12A-15B , Applicants have discovered a new method of reducing the size of the fragments 40 into which a glass substrate 10 shatters upon fracture 42. The method includes forming a glass substrate 10 that shatters upon fracture 42 into fragments 40 having a first size 48 (see Figure 12A and12B ). As discussed, the formed glass substrate 10 is in the first position 38 and is tempered. However, the resulting tensile stress of the glass substrate 10 is insufficient to cause the glass substrate 10 to shatter into small fragments 40 upon breaking 42. The method further includes bending the glass substrate 10 to a second position 44 and holding the glass substrate 10 in the second position. A structural component, such as a glass window frame, or a component 50 of a material, such as an adhesive, can hold the glass substrate 10 in the second position 44. In other words, in one embodiment, bending and holding the glass substrate 10 in the second position 44 is achieved at ambient temperature by a structural component of a product 52 that utilizes the glass substrate 10. In one or more embodiments, an adhesive can be used to permanently hold the glass substrate 10 in the second position 44 by adhering the glass substrate to a curved lower surface (not shown).

[0106] Held in the second position 44, the glass substrate 10 shatters into fragments 40 having a second size 54 upon breaking 42 of the glass substrate 10. The fragments 40 having the second size 54 are smaller than the fragments 40 having the first size 48. In some embodiments, the fragments 40 having the second size 54 have lengths 56 and widths 58 that are approximately equal to each other, and in some embodiments, approximately equal to the thickness 18 (i.e., a cleaving behavior). In one embodiment, forming the glass substrate 10 includes forming the glass substrate 10 having a thickness 18 of 2 mm or less. In one embodiment, bending the glass substrate 10 includes uniaxially bending the glass substrate 10 along a bending axis 46 of the glass substrate 10, as in the embodiment shown in Figures 12A-13B In one embodiment, forming the glass substrate 10 includes forming the glass substrate 10 having a curved first surface 12, as in the embodiments shown in Figure 12A and Figure 12B In one embodiment, bending the glass substrate 10 to the second position 44 includes bending the glass substrate 10 such that the first surface 12 is curved at the second position 44, as in the embodiment shown in Figure 13A

[0107] In one embodiment, bending the glass substrate 10 includes biaxial bending, as in the embodiment shown in Figures 14A-15B The biaxial bending of the glass substrate 10 is a bending of the glass substrate 10 at a first bending axis 46a and a second bending axis 46b. Note that in Figure 14A ​In the embodiment shown by -B, forming the glass substrate 10 includes forming the glass substrate 10 with a first surface 12 that is planar (i.e., not curved). The component 50 of the product 52 bends the glass substrate 10 to the second position 44 or holds the glass substrate 10 at the second position 44. The fragments 40 of the second size 54 that result when the glass substrate 10 is fractured 42 at the second position 44 are smaller than the fragments 40 of the first size 48 that result when the glass substrate 10 is fractured 42 at the first position 38. Because the glass substrate 10 is biaxially curved at the second position 44, the fragments 40 form an in-plane isotropic fracture pattern 60 when the glass substrate 10 is fractured 42 at the glass substrate 10.

[0108] In any case, the glass substrate 10 is formed and tempered at the first position 38, but can be forced into the second position 44. At the first position 38, the tensile energy of the glass substrate 10 (imposed via tempering) is insufficient to cause the glass substrate 10 to fracture 42 into fragments 40 having the second size 54 that is small. Rather, the tensile energy causes the glass substrate 10 to fracture 42 into fragments 40 having the first size 48 (the larger size). However, upon bending the glass substrate 10 to the second position 44, the stress profile of the glass substrate 10 changes relative to the first position 38, increasing the tensile stress at certain portions of the central region 36. At the second position 44, the tensile energy of the glass substrate 10 is sufficient to cause the glass substrate 10 to fracture 42 into fragments 40 having the second size 54 (i.e., small fragments 40). In some embodiments, as shown in Figure 14A the glass substrate 10 is formed and tempered to be planar. In other words, at the first position 38, the first surface 12 and the second surface 14 of the glass substrate 10 are planar. Thus, at the first position 38, the glass substrate 10 is more planar than the glass substrate 10 at the second position 44. In some embodiments, as shown in Figure 13B the fragments 40 of the second size 54 (the small fragments) are generally cuboid, having a length 56, a width 58, and a thickness 18, which generally all have equal values. In some embodiments, as shown in Figure 13A and 13B the glass substrate 10 is uniaxially curved at the second position 44 along a bending axis 46. In some embodiments, as shown in Figure 15A and 15B the glass substrate 10 is biaxially curved at the second position 44 along two bending axes 46a, 46b (a first bending axis 46a and a second bending axis 46b). In some embodiments, the thickness 18 of the glass substrate 10 is 2 mm or less.

[0109] In other embodiments, however, as shown in Figures 12A-13BAs shown in FIG. 1, the glass substrate 10 is formed and tempered to be curved. In other words, at the first position 38, the first surface 12 and the second surface 14 of the glass substrate 10 are curved (not flat). The glass substrate 10 is then curved to the second position 44. At the second position 44, the glass substrate 10 is flatter than the glass substrate 10 at the first position 38. For example, at the second position 44, the first surface 12 and the second surface 14 can be planar (not curved).

[0110] In some embodiments, the glass substrate 10 is incorporated into a product 52. The product 52 includes the glass substrate 10 and a component 50 that curves the glass substrate 10 from the first position 38 at which the glass substrate 10 is formed and tempered to the second position 44. In one or more embodiments, the product 52 includes the glass substrate 10 and the component 50 that holds or secures the glass substrate 10 in the second position 44. At the first position 38, the tensile energy of the glass substrate 10 is insufficient to cause the glass substrate 10 to shatter into pieces of the second size 54 (i.e., small pieces) upon the break 42. With the component 50 forcing the glass substrate 10 into the second position 44 or the component 50 securing the glass substrate 10 in the second position 44, the tensile energy of the glass substrate 10 is sufficient to cause the glass substrate 10 to shatter into pieces of the second size 54 upon the break 42. In one embodiment, as shown in FIG. 1, the product 52 is a safety glass 62 in which the glass substrate 10 must shatter into small pieces 40 and eject outward upon the break 42. Note that in this embodiment, the glass substrate 10 has the first surface 12 and the second surface 14 facing in opposite directions. Because the component 50 curves the glass substrate 10 along the bend axis 46 in a direction that compresses the first surface 12 (or the component 50 secures the glass substrate in the second position along the bend axis 46 in a direction that compresses the first surface 12), the first surface 12 has a higher compressive stress than the second surface 14. This can be particularly beneficial for the safety glass 62. In the embodiment of FIG. 2, the product 52 is a consumer electronic device 64, such as a watch 66, configured to be worn on the wrist of a person 68 (see also FIG. 3). In one or more embodiments, the product 52 is an automotive interior cover glass used in an automotive interior system. Figures 13A-13B Figure 15A Figure 15B In the embodiment of FIG. 2, the product 52 is a consumer electronic device 64, such as a watch 66, configured to be worn on the wrist of a person 68 (see also FIG. 3). In one or more embodiments, the product 52 is an automotive interior cover glass used in an automotive interior system. Figure 19

[0111] To continue the analysis of the model, the square stress integrals x and y can be determined for each stress component (σ ​​​The comparisons are then made to determine the orientation deviation of breakage during uniaxial bending (i.e., which direction in the xy plane typically results in breakage). If the glass substrate 10 bends along the y-axis (bending axis 46 in the running example), it experiences bending stress along the x-direction but not in the y-direction. Therefore, the square stress integral along the x-direction... The square stress integral is different from that along the y-direction. In addition to the bending stress σ experienced only along the x-direction bendmax In addition, and The equations will be equal. Therefore, assume σ y Along the bending axis 46 and therefore σ bendmax The value is zero, and σ x It has all the bending stresses, and therefore has σ. bendmax Given the value of , the orientation deviation OB of the fragment can be quantified as follows:

[0112]

[0113] Now refer to Figure 16 The orientation deviation of the fragments is described as being due to the tensile stress (central tension, σ) already present during tempering. CT ) and the tensile stress (bending stress, σ) added to the glass substrate 10 due to bending. bendmax The figure shows that the more bending stress is added, the greater the orientation deviation of the fragments. In this case, because the bending is along the y-axis, stress is added in the x-direction, so the orientation of the fragments is biased along the bending axis 46 (in this case, the y-axis). In other words, the fracture 42 between the two fragments 40 is biased parallel to the bending axis 46.

[0114] Now refer to Figure 17 A dynamic fracture simulation using kinetic theory was performed on a computer to visualize the fragmentation of the glass substrate 10 at fracture 42. The simulation assumed that the glass substrate 10 was tempered and fragmented into small fragments 40 at fracture 42, with a central tension (tensile stress) of 105.27 MPa. The simulation assumed the dimensions of the glass substrate 10 were: width 20 = 5 mm, length 26 = 5 mm, and thickness 18 = 0.55 mm. The residual stress distribution of the tempered glass substrate 10 is shown below. Figure 6 As shown in the figure. The simulation assumes that the bending axis 46 is vertical and the applied bending surface stress is 137 MPa. The bending stress distribution applied to the glass substrate 10 is as follows. Figure 7 As shown. The calculated orientation deviation OB of the fragment is 1.39. The bars on the right (0 to 0.5) represent volumetric damage to the material, where a value greater than 0.34 indicates that fracture 42 has penetrated to the first surface 12. Figure 17The visualization of the above analysis model shows that the fragmentation at the break 42 causes the break 42 to generally extend parallel to the bend axis 46 (the y-axis, up and down) and the break to bifurcate 70 after a relatively short distance (the relatively short portion of the break 42 perpendicular). The bending increases the stress in the horizontal x-direction and creates the relatively short portion of the break 42 that is perpendicular.

[0115] The above analysis model shows that applying a uniaxial bend to the glass substrate 10 generally directs the break 42 of the glass substrate 10 in a particular direction. In this regard, reference is now made to Figures 18-23 The consumer electronic device 64 includes the glass substrate 10. The glass substrate 10 is disposed over a display screen 72. The glass substrate 10 need not be disposed over the display screen 72 abutting the display screen 72, but can be disposed over the display screen 72 abutting the display screen 72. As described above, the glass substrate 10 has a length 26 and a width 20. The width 20 extends from the first side 22 to the second side 24 of the glass substrate 10. The consumer electronic device 64 further includes a component 50 that bends the glass substrate 10 along the bend axis 46 from a first position 38 Figure 18 ) to a second position 44 Figure 19 and Figure 20 ) of the glass substrate 10. As described above with respect to the analysis model, when a break 42 of the glass substrate 10 is formed at the second position 44 Figure 21 ), the break 42 generally propagates toward the first side 22 or the second side 24 of the glass substrate 10, generally parallel to the bend axis 46. Note that the break 42 can bifurcate 70 while still propagating toward the first side 22 or the second side 24 of the glass substrate 10. The second side 24 of the glass substrate 10. It is advantageous for the consumer electronic device 52 for the break 42 to propagate to the first side 22 or the second side 24 of the glass substrate 10 so that the break 42 is terminated as soon as possible. Furthermore, forcing the break 42 to propagate to the first side 22 or the second side 24 of the glass substrate 10 (by the bend of the glass substrate 10) prevents the break 42 from propagating along the entire length 26 of the glass substrate 10. Users often read text displayed by the display screen 72 from left to right (or right to left, depending on the language). A break 42 that propagates along the length 26 of the glass substrate 10 will reduce the user's ability to read such text.

[0116] As described above, the glass substrate 10 can be tempered at the first position 38 (and in this embodiment, it is so) to extend the first compressive stress layer 28 from the first surface 12 of the glass substrate 10 to the layer depth (DOC) within the thickness 18 of the glass substrate 10. Furthermore, as described above, by bending the glass substrate 10 from the first position 38 to the second position 44 in this manner, the component 50 increases the compressive stress within the first layer 28. Therefore, the bending of the glass substrate 10 within the consumer electronics device 64 provides two advantages: forcing the fracture 42 to be biased along the bending axis 46 (and thus biased towards the first side 22 or the second side 24) and increasing the compressive stress at the first layer 28, which can help reduce the risk of the glass substrate 10 breaking in the first case.

[0117] In the illustrated embodiment, as described above, the component 50 that bends the glass substrate 10 from the first position 38 to the second position 44 can be a structural component similar to a frame that compresses the glass substrate 10 from the first position 38 to the second position 44. Alternatively, the component 50 that bends the glass substrate 10 from the first position 38 to the second position 44 can pull the glass substrate 10 to the second position 44. For example, as... Figure 22 and Figure 23 The embodiments shown refer to consumer electronic devices 64 or automotive interior systems (such as...). Figure 25 (As shown) may include an adhesive layer 74 for securing the glass substrate 10 to the second position 44. In other words, the component 50 that bends the glass substrate 10 from the first position 38 to the second position 44 is the adhesive layer 74. In this embodiment, the adhesive layer 74 is disposed between the glass substrate 10 and the display screen 72, and the back plate 76 supports the glass substrate 10 and the display screen 72. The consumer electronic device 64 may be a person 68 (see...) Figure 24 This can be any electronic device used, such as a telephone 78, a watch 66, or a tablet computer 80. It should be noted that in the embodiment of the watch 66, the glass substrate 10 may be non-planar (curved) at the second position 44, while in the embodiments of the telephone 78 and the tablet computer 80, the glass substrate 10 may be planar (flat). In any case, during the assembly of the consumer electronic device 64, the glass substrate 10 is bent from the first position 38 to the second position 44 to achieve the aforementioned advantages.

[0118] Now refer to Figure 25 The automotive interior system 100 may include one or more glass substrates 10 in a second position with at least uniaxial bending. Figure 24In some embodiments, the automotive interior system includes a center console 111 that includes two glass substrates 10 that are maintained, secured, or held in the second position by a component 110. In one or more embodiments, the automotive interior system 10 includes an instrument panel 200 that has a curved component 220 that maintains, secures, or holds the glass substrate 10 in the second position. Optionally, the instrument panel 250 also includes a component 240 that maintains, secures, or holds the glass substrate 10 in the second position. The steering wheel 300 of the automotive interior system 10 can include a component 320 that maintains, secures, or holds the glass substrate 10 in the second position. In Figure 24 In each of the examples shown, the glass substrate 10 is disposed over a display screen and / or touch panel or touch surface. As described above, the glass substrate 10 has a length 26 and a width 20. The width 20 extends from the first side 22 to the second side 24 of the glass substrate 10. The component in each of these embodiments can be a structural component such as a cover or frame. The component can include one or more adhesives that maintain, secure, or hold the glass substrate in the second position. The automotive interior system can include an instrument panel, display, touch screen, or touch surface disposed on an instrument panel, center console, armrest, seat back, headrest, or other surface within the interior of an automobile, sea vessel, aircraft, drone, or the like.

[0119] As described above, the glass substrate 10 can be tempered at the first position 38 (and in this embodiment is) to have the first compressive stress layer 28 extend from the first surface 12 of the glass substrate 10 to a depth of layer (DOC) within the thickness 18 of the glass substrate 10. Further, as described above, by bending the glass substrate 10 from the first position 38 to the second position 44 in this manner, the component 50 increases the compressive stress within the first layer 28. Thus, the bending of the glass substrate 10 within the automotive interior system 64 provides two advantages: forcing the fracture 42 to be biased along the bend axis 46 (and thus to be biased toward the first side 22 or the second side 24) and increasing the compressive stress at the first layer 28, which can help to reduce the risk of the glass substrate 10 fracturing in the first instance.

[0120] In the illustrated embodiment, the component 50 that bends the glass substrate 10 from the first position 38 to the second position 44 (and maintains, secures, or holds the glass substrate in the second position 44) can be a structural component similar to a frame and / or an adhesive that compresses the glass substrate 10 from the first position 38 to the second position 44 and maintains, secures, or holds the glass substrate in the second position, as described above.

[0121] Aspect (1) pertains to a glass substrate comprising: a first position in which a tensile stress of the glass substrate is insufficient to cause the glass substrate to shatter into small pieces upon the glass substrate breaking; and a second position in which the glass substrate is bent relative to the first position, and in which a tensile stress of the glass substrate is sufficient to cause the glass substrate to shatter into small pieces upon the glass substrate breaking.

[0122] Aspect (2) pertains to the glass substrate of Aspect (1), further comprising: a first surface and a second surface; wherein, in the first position, the first surface and the second surface of the glass substrate are planar.

[0123] Aspect (3) pertains to the glass substrate of Aspect (1) or Aspect (2), further comprising: a first surface and a second surface; wherein, in the second position, the first surface and the second surface of the glass substrate are planar.

[0124] Aspect (4) pertains to the glass substrate of any one of Aspects (1) through (3), wherein the small pieces are generally cubical.

[0125] Aspect (5) pertains to the glass substrate of any one of Aspects (1) through (4), in the second position, the glass substrate is uniaxially bent along a bending axis of the glass substrate.

[0126] Aspect (6) pertains to the glass substrate of any one of Aspects (1) through (5), in the second position, the glass substrate is biaxially bent along two bending axes of the glass substrate.

[0127] Aspect (7) pertains to the glass substrate of any one of Aspects (1) through (6), wherein, in the first position, the glass substrate is flatter than the glass substrate in the second position.

[0128] Aspect (8) pertains to the glass substrate of any one of Aspects (1) through (7), wherein, in the second position, the glass substrate is flatter than the glass substrate in the first position.

[0129] Aspect (9) pertains to the glass substrate of any one of Aspects (1) through (8), further comprising: a thickness of 2 mm or less.

[0130] Aspect (10) pertains to a method of increasing a compressive stress at a layer of a glass substrate, comprising: providing a glass substrate; applying a first compressive stress within a first layer from a first surface of the glass substrate and within a second layer from a second surface of the glass substrate; and bending the glass substrate along an axis of the glass substrate to increase the compressive stress to the first compressive stress within the second layer.

[0131] Aspect (11) pertains to the method of aspect (10), wherein applying the first compressive stress within the first and second layers of the glass substrate comprises thermally tempering, mechanically tempering, or chemically tempering the glass substrate.

[0132] Aspect (12) pertains to the method of aspect (10) or aspect (11), wherein applying the first compressive stress within the first and second layers of the glass substrate comprises chemically tempering the glass substrate.

[0133] Aspect (13) pertains to the method of any one of aspects (10) through (12), wherein the second surface of the glass substrate is a top surface of the glass substrate.

[0134] Aspect (14) pertains to a method of reducing the size of fragments into which a glass substrate breaks when the glass substrate is fractured, comprising: providing a glass substrate that breaks into fragments having a first size when the glass substrate is fractured; and bending the glass substrate to a second position and holding the glass substrate in the second position such that the glass substrate breaks into fragments having a second size when the glass substrate is fractured; wherein the fragments having the second size are smaller than the fragments having the first size.

[0135] Aspect (15) pertains to the method of aspect (14), wherein forming the glass substrate comprises forming the glass substrate having a thickness of 2 mm or less.

[0136] Aspect (16) pertains to the method of aspect (14) or aspect (15), wherein bending the glass substrate comprises biaxial bending of the glass substrate.

[0137] Aspect (17) pertains to the method of aspect (16), wherein the glass substrate breaks into fragments when fractured at the second position that form an in-plane isotropic fracture pattern.

[0138] Aspect (18) pertains to the method of any one of aspects (14) through (17), wherein bending the glass substrate comprises uniaxial bending of the glass substrate along a bending axis of the glass substrate.

[0139] Aspect (19) pertains to the method of any one of aspects (14) through (18), wherein forming the glass substrate comprises forming the glass substrate having a first planar surface.

[0140] Aspect (20) pertains to the method of any one of aspects (14) through (19), wherein forming the glass substrate comprises forming the glass substrate having a first curved surface; and wherein bending the glass substrate to a second position comprises bending the glass substrate such that the first surface is less curved at the second position than at the first position.

[0141] Aspect (21) pertains to the method of any one of aspects (14) through (20), wherein the bending and holding the glass substrate in the second position is achieved by using a structural component of a product of the glass substrate at ambient temperature.

[0142] Aspect (22) pertains to a product comprising: a glass substrate having a first position, wherein the tensile energy of the glass substrate is insufficient to cause the glass substrate to shatter into small pieces upon the glass substrate breaking; and a component that bends the glass substrate from its first position to a second position, wherein the tensile energy of the glass substrate is sufficient to cause the glass substrate to shatter into small pieces upon the glass substrate breaking.

[0143] Aspect (23) pertains to the product of aspect (22), wherein the product is a consumer electronic device configured to be worn on a person's wrist.

[0144] Aspect (24) pertains to the product of aspect (22), wherein the product is a safety glass.

[0145] Aspect (25) pertains to the product of aspect (22), wherein the product is an automotive interior cover glass system.

[0146] Aspect (26) pertains to the product of any one of aspects (22) through (24), wherein the glass substrate has a first surface and a second surface; and wherein, in the second position, the first surface has a higher compressive stress than the second surface.

[0147] Aspect (27) pertains to a consumer electronic device or an automotive interior electronic device comprising: a glass substrate disposed over a display screen, the glass substrate having a length, and a width extending from a first side to a second side; and a component that bends the glass substrate along a bend axis from a first position to a second position bent relative to the first position, such that when the glass substrate breaks in the second position, the break generally propagates toward the first side or the second side of the glass substrate; wherein the bend axis is generally parallel to the width of the glass substrate.

[0148] Aspect (28) pertains to the consumer electronic device or the automotive interior electronic device of aspect (27), wherein, in the first position, the glass substrate has a first compressive stress layer extending from a first surface; and

[0149] wherein the component that bends the glass substrate to the second position increases the compressive stress within the first layer.

[0150] Aspect (29) pertains to the consumer electronic device or the automotive interior electronic device of aspect (27) or aspect (28), wherein the component that bends the glass substrate compresses the glass substrate from the first position to the second position.

[0151] Aspect (30) pertains to the consumer electronic device or automotive interior electronic device of any one of Aspects (27) through (29), wherein the means for bending the glass substrate is an adhesive layer.

[0152] Aspect (31) pertains to the consumer electronic device or automotive interior electronic device of any one of Aspects (27) through (30), wherein the consumer electronic device or automotive interior electronic device is a smartphone, a tablet, a watch, or an automotive display.

[0153] Aspect (32) pertains to an article comprising: a glass substrate having a first position, wherein the tensile energy of the glass substrate is insufficient to cause the glass substrate to shatter into small pieces upon fracture of the glass substrate; and means for bending the glass substrate and holding the glass substrate in a second position, wherein the tensile energy of the glass substrate is sufficient to cause the glass substrate to shatter into small pieces upon fracture of the glass substrate.

[0154] Aspect (33) pertains to the article of Aspect (32), wherein the article is a consumer electronic device configured to be worn on a person's wrist.

[0155] Aspect (34) pertains to the article of Aspect (32), wherein the article is a safety glass.

[0156] Aspect (35) pertains to the article of Aspect (32), wherein the article is an automotive interior cover glass system.

[0157] Aspect (36) pertains to the article of any one of Aspects (32) through (35), wherein the glass substrate has a first surface and a second surface; and wherein, in the second position, the first surface has a higher compressive stress than the second surface.

[0158] Aspect (37) pertains to a consumer electronic device or automotive interior electronic device comprising: a glass substrate disposed over a display screen, the glass substrate having a length and a width extending from a first side to a second side; and means for bending the glass substrate along a bend axis from a first position and holding the glass substrate in a second position bent relative to the first position, such that, when the glass substrate fractures in the second position, the fracture generally propagates toward the first side or the second side of the glass substrate; wherein the bend axis is generally parallel to the width of the glass substrate.

[0159] Aspect (38) pertains to the consumer electronic device or automotive interior electronic device of Aspect (37), wherein, in the first position, the glass substrate has a first compressive stress layer extending from a first surface; and wherein the means for bending the glass substrate to the second position increases the compressive stress within the first layer.

[0160] Aspect (39) pertains to the consumer electronic device or automotive interior electronic device of Aspect (37) or Aspect (38), wherein the means for bending the glass substrate compresses the glass substrate from the first position to the second position.

[0161] Aspect (40) pertains to the consumer electronic device or automotive interior electronic device of any one of Aspects (37) through (39), wherein the means for bending the glass substrate is an adhesive layer.

[0162] Aspect (41) pertains to the consumer electronic device or automotive interior electronic device of any one of Aspects (37) or (40), wherein the consumer electronic device is a smartphone, a tablet, a watch, or an automotive display.

[0163] It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the spirit or scope of the claims.

Claims

1. A product comprising: a tempered glass substrate comprising a first surface, a second surface, and a first position in which the tempered glass substrate is not bent, the tempered glass substrate having a thickness of 2 mm or less defined between the first surface and the second surface; and a component that forces the tempered glass substrate into a second position and holds the tempered glass substrate in the second position in which the tempered glass substrate is cold bent relative to the first position, wherein, in the second position, upon fracture, the tempered glass substrate shatters into cubic fragments having a length and a width approximately equal to the thickness of the tempered glass substrate.

2. The product of claim 1, wherein, In the second position, the first surface and the second surface of the tempered glass substrate are flatter than the first surface and the second surface of the tempered glass substrate in the first position.

3. The product of any one of claims 1-2, wherein, The component forces the tempered glass substrate to be uniaxially bent in the second position along a bending axis of the tempered glass substrate.

4. The product of claim 3, wherein, Cracks in the tempered glass substrate propagate toward a side of the tempered glass substrate in a direction parallel to the bending axis, wherein the direction is perpendicular to a length of the tempered glass substrate.

5. The product of any one of claims 1-2, wherein, The component forces the tempered glass substrate to be biaxially bent in the second position along two bending axes of the tempered glass substrate.

6. The product of any of claims 1-2, wherein: the tempered glass substrate in the first position has a tensile energy that does not cause the glass substrate to shatter into cubic fragments upon fracture of the tempered glass substrate; in the second position, the tensile energy of the tempered glass substrate causes the tempered glass substrate to shatter into cubic fragments upon fracture of the tempered glass substrate.

7. The product of any of claims 1-2, wherein: in the first position, the tempered glass substrate has a first layer of compressive stress extending from the first surface, in the second position, the compressive stress of the first layer is higher than the compressive stress of the first position.

8. The product of any of claims 1-2, wherein the product is a smartphone, a tablet, a watch, or an automotive display.

9. A consumer electronic device or an automotive interior electronic device comprising: a glass substrate disposed over a display screen, the glass substrate having a length and a width extending from a first side to a second side, wherein, in a first position, the glass substrate has a first layer of compressive stress extending from a first surface; and a component that bends the glass substrate along a single bending axis from the first position to a second position that is bent relative to the first position and holds the glass substrate in the second position such that, upon formation of a plurality of cracks in the glass substrate, the plurality of cracks have an orientation bias along the bending axis; wherein the bending axis is parallel to the width of the glass substrate such that the plurality of cracks do not propagate along an entire length of the glass substrate.

10. The consumer electronic device or automotive interior electronic device of claim 9, wherein, The component that bends the glass substrate to the second position increases the compressive stress in the first layer.

11. The consumer electronic device or automotive interior electronic device of any of claims 9-10, wherein, The component that bends the glass substrate is an adhesive layer.

12. The consumer electronic device or automotive interior electronic device of any of claims 9-10, wherein the plurality of cracks includes bifurcated portions extending along the bend axis.

13. The consumer electronic device or automotive interior electronic device of any of claims 9-10, wherein the consumer electronic device is a smartphone, a tablet, a watch, or an automotive display.

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