Flat glass element for cover

Abstract

There is provided a flat glass element (5) for a cover (1) of an electronic display (3), where the flat glass element (5) has two opposite sides (50, 51), where the glass of the glass element (5) has a varying bending stiffness along at least one line across the glass element (5), the varying bending stiffness being provided by at least one first section (7), the at least one first section (7) has a reduced bending stiffness relative to the bending stiffness of a second section (6, 8) adjoining the at least one first section (7) such that the glass element (5) can be bent at the first section (7), the reduced stiffness of the first section (7) being achieved by a pattern (70) of reduced stiffness, the pattern (70) comprising an arrangement of openings (19) and / or thinned portions (20), and wherein the edge (9) of the glass element (5) is recessed inwardly at the first section (7).

Description

Technical Field

[0001] This invention generally relates to a structured glass plate that can be used as a cover for electronic displays, particularly displays for mobile devices. In particular, this invention relates to a glass element for flexible electronic displays. Background Technology

[0002] Flexible electronic displays, especially foldable electronic displays, have been extensively researched and developed. However, providing displays that are both flexible and durable has proven to be challenging.

[0003] In a typical foldable display stack design, a cover is attached to the OLED display to protect it. Typically, the cover consists of an ultra-thin glass layer, less than about 70µm thick, attached to the top of the OLED display via an adhesive layer. While ultra-thin glass layers less than 70µm thick can be bent to the small bending radius required for foldable displays, they are prone to breakage under severe localized impacts. A polymer layer can be applied to the top surface of the ultra-thin glass layer to protect it from scratches, mechanical shocks, and breakage.

[0004] Alternatively, a thicker rigid glass layer with a thickness greater than about 120 µm or more can be used to increase mechanical stability, at least in the non-bending section, wherein the flexibility of the thicker glass layer is improved in the bending section, for example, by locally thinned glass or locally structured glass. Throughout the bending section, the locally thinned glass is reduced to less than about 70 µm. The locally structured glass can be arranged with openings or thinned sections in the bending section such that the greater thickness of the bending section is at least partially maintained.

[0005] For example, patent document US 2022 / 0103672 A1 discloses a flexible display with a glass layer comprising multiple openings filled with a filler material. It shows openings of different shapes. Since the glass layer is located above the display layer and faces the user, the refractive index of the filler material must match that of the glass. However, the structured flexible regions of such glass panels are quite fragile and susceptible to damage, such as breakage, during the handling and processing of the structured glass panels. In particular, operations during etching and chemical strengthening processes have proven very difficult in this regard. Summary of the Invention

[0006] Addressing these drawbacks of cover glass for flexible displays, the object of the present invention is to improve operation and increase stability during processing. This object is achieved through the technical subject matter of the independent claims. Advantageous improvements of the invention are defined in the corresponding dependent claims.

[0007] According to the present invention, a flat glass element for a cover of an electronic display is provided, the flat glass element having two opposing sides. The glass of the glass element has a varying bending stiffness along at least one line spanning the glass element. This varying bending stiffness is provided by at least one first segment, the bending stiffness of which is reduced relative to a second segment adjacent to the at least one first segment, allowing the glass element to bend at the first segment. Thus, the first segment is analogous to a folded region. The reduced stiffness of the first segment is achieved by a stiffness-reducing pattern, the pattern including arrangements of openings or thinnings. For ease of handling and improved stability, the edge of the glass element extending along the first and second segments is recessed inward at the first segment. The term "edge" as used herein should be understood as the outline of the glass element when viewed in a top view, i.e., along one of its sides. This means, for example, that if the glass element is placed on a flat surface with its edge, the edge contacts the plane in the second segment, but remains at a distance from the flat surface in the first segment. Therefore, the feature of a recessed edge specifically means that the edge is recessed along its entire length in the first segment. The example above illustrates that stability is improved because the flat support surface does not contact the vulnerable edge region of the structured first segment. By recessing the sensitive structured region (which has reduced bending stiffness), impact resistance can be improved, and the risk of breakage in a side impact can be significantly reduced.

[0008] As described above, the flat glass element for the cover of an electronic display can be manufactured using a method including the following steps: - A glass plate is provided, the edge of which has at least one recess, specifically formed by removing glass along a segment of the glass plate at its edge. - By introducing multiple openings or thinning portions in the first section, the bending stiffness of the first section is reduced. The first section is arranged between two second sections adjacent to the first section, wherein the first section extends across the glass plate such that the first section of the flat glass element produced from the glass plate terminates at the recess.

[0009] The formation of the recess can be divided into several steps. In one embodiment, the outline of the recess at the edge can be formed only partially in the first step along with the opening or thinning. However, a reinforced bridging element can be held attached to the glass plate by a narrow web. Then, after breaking the web and removing the reinforced bridging element, the complete outline can be obtained. The next step can be completed later, for example, after completing the structuring, chemical treatment, and final coating steps. Therefore, the order of the above steps can vary. However, preferably, the step of forming the recess is performed at least partially before introducing the stiffness-reducing structure with the opening or thinning. This avoids the need to remove the glass from the fragile edge of the first segment after introducing the opening. Attached Figure Description

[0010] The invention will be more fully understood through detailed description and accompanying drawings, wherein: Figure 1a This is a top view of the side of one embodiment of the glass element.

[0011] Figure 1b It shows Figure 1a A top view of the first variant of the embodiment.

[0012] Figure 2a This is a top view of the side of another embodiment of the glass element.

[0013] Figure 2b It shows Figure 2a A top view of the first variant of the embodiment.

[0014] Figure 3 Shown in perspective Figure 1b A variant of .

[0015] Figure 4a A variant of a flat glass element with multiple first segments is shown.

[0016] Figure 4b A side view of a flat glass element with multiple first sections is shown.

[0017] Figure 5 It shows Figure 4a or Figure 4b The embodiment is shown in a folded side view.

[0018] Figures 6 to 9 The steps of a method for producing flat glass components are shown.

[0019] Figure 10 Figure 1 or Figure 9 Variations of the embodiments.

[0020] Figure 11A cross-section of a first chemically strengthened flat glass element is shown.

[0021] Figure 12 An embodiment of a glass element with a detachable bridging section is shown.

[0022] Figure 13 It shows Figure 12 Enlarged image.

[0023] Figure 14 The details of the flat glass element at the recess after the bridging section has been removed are shown.

[0024] Figure 15 and Figure 16 It shows Figure 12 Variations of the embodiments.

[0025] Figure 17 An embodiment of a flat glass element with a removable support attached to the edge is shown to facilitate operation of the flat glass element.

[0026] Figure 18 A cross-section of a first variant of the cover for an electronic display is shown.

[0027] Figure 19 A cross-section of a second variant of the cover for an electronic display is shown. Detailed Implementation

[0028] Figure 1a A top view of one of the opposing sides 50 of a flat glass element 5 is shown. The glass element 5 has a varying bending stiffness imparted by a stiffness-reducing structure 70 within a first segment 7. The first segment 7 is adjacent to two second segments 6, 8 and is located at the center between the two second segments 6, 8. Compared to the adjacent second segments 6, 8, the bending stiffness of the first segment 7 of the glass element 5 is lower due to the structure 70. Therefore, the glass element 5 can be easily bent, with the bending axis 24 extending along the first segment 7 and between the second segments 6, 8. The structure 70 of the first segment 7 includes an arrangement of openings 19. Although the glass element 5 has a generally rectangular profile, the edges 9 do not extend in a straight line between the second segments 6, 8 and the intermediate first segment 7. Typically, it is preferred that, as shown in FIG. 1, the first segment 7 extends across the entire flat glass element 5 such that the first segment 7 terminates at the edges 9 of the opposing sides. Thus, segment 7 constitutes a hinge that allows the glass element 5 to be folded at the first segment 7.

[0029] Typically, and not limited to the specific example shown, the glass element 5 has a recess 93 in the first section 7, such that the edge 9 of the glass element 5 in the first section 7 is recessed inward. Typically, and not limited to the specific embodiment, this feature should be understood as the outermost portion of the edge 9 within the first section 7 being recessed inward relative to the position of the edge 9 in the adjacent second sections 6, 8. For example, in Figure 1a As can be further seen, and according to a preferred embodiment, the segment 90 of the edge 9 extending along the first segment 7 is discontinuous, but is blocked by the opening 19. In other words, the edge 9 within the first segment 7 crosses the opening 19. The general outline of the edge 9 (i.e., the portion ignoring or crossing the truncated opening 19) is shown in dashed lines. The characteristics and appearance of the edge 9 within the first segment 7, i.e., the characteristics of the edge 9 within the first segment 7 being blocked by the opening 19 of the stiffness-reducing structure 70, are not limited to the specific example shown, but are a generally preferred configuration of the glass element 5. This embodiment ensures that the glass element 5 also has high flexibility at the edge of the first segment 7. According to another generally preferred embodiment, the openings 19 are arranged along a plurality of parallel rows 23. Furthermore, as also achieved in the illustrated example, the openings 19 are staggered. This arrangement achieves high flexibility of the first segment 7. Also achieved as in the illustrated example, due to this staggered arrangement, the edge 9 within the segment 90 can be positioned such that the edge 9 crosses the opening 19 every other row 23.

[0030] Together with the recessed portion of the first segment 7 along with the edge 9, the edge 9 has an inwardly skewed segment 91 at the position where it transitions from the second segments 6, 8 to the first segment 7.

[0031] Figure 1b It shows Figure 1a A variation of the embodiment. According to this variation, the edge 9 is at least partially chamfered along the second segments 6, 8. In this embodiment, the edge along the first segment 7 is not chamfered. Without being limited to the specific example shown, the width of the chamfer is less than the depth of the recess.

[0032] Figure 2a Another embodiment of the glass element is shown. In this embodiment, the stiffness-reducing structure 70 in the first segment 7 includes an arrangement of thinning portions 20. This differs from the embodiment according to... Figure 1a In the embodiment, opening 19 has a thinned portion that is a blind hole, wherein a thin glass layer is retained at the bottom of the thinned portion. The retained glass thickness is preferably 10µm to 70µm, more preferably 20µm to 50µm. In the illustrated embodiment, the thinned portion 20 is a parallel groove, the longitudinal direction of which is parallel to the intended bending axis, and these grooves extend throughout the first segment 7. However, the thinned portion can also have any other shape, such as an elongated blind hole.

[0033] Figure 2b It shows Figure 2b A variation of the embodiment. According to this variation, the edge 9 is at least partially chamfered along the second segments 6, 8, and the edge 9 along the first segment 7 is also chamfered. However, it is also possible not to chamfer the edge 9 along the first segment 7.

[0034] exist Figure 1a and Figure 2a In one embodiment, the stiffness-reducing structure 70 within the first segment 7 includes an elongated opening 19 or an elongated thinning portion 20, the longitudinal axis of which is parallel to the bending axis. However, after mounting such a glass element with a structured first segment onto an OLED display, this structure may have the following disadvantage: undesirable moiré effects may occur in the first segment 7, possibly due to interference between the periodic arrangement of the individual LEDs in the OLED display and the periodic structure of the cover glass in the first segment 7. Therefore, according to Figure 1a and Figure 2a The elongated opening 19 or the elongated thinning portion 20 in the embodiments are merely specific examples of stiffness-reducing structures.

[0035] In EP 22187862, the entire contents of which are incorporated herein by reference, numerous alternative structures are provided designed to reduce undesirable moiré effects. For example, a stiffness-reducing structure may include an elongated opening 19 or an elongated thinning portion 20 that is inclined relative to the central axis of the first segment, thereby avoiding or reducing undesirable moiré effects in the first segment 7. Alternatively, the structure may include elongated thinning portions 20 or openings 19 that are not straight but extend along parallel wavy lines, wherein the main direction of the wavy lines is parallel to or inclined relative to the central axis of the first segment. Alternatively, the structure may include a non-periodic structure of the thinning portions 20 and / or openings 19 that can be arranged in any pattern. Any interference between such a non-periodic structure and the periodic arrangement of the LEDs in an OLED display will be significantly reduced. More possible stiffness-reducing structures for reducing undesirable moiré effects can be found in EP 22187862, where most stiffness-reducing structures can be applied to both openings 19 and thinning portions 20 simultaneously.

[0036] Figure 3 The perspective view shows the results based on Figure 1b Glass element 5 in the embodiment. For simplicity, Figure 3The stiffness-reducing structure 70 with opening 19 is omitted. If the stiffness-reducing structure 70 includes opening 19 extending to the edge 9 of the first segment 7, it is advantageous to chamfer the edges 9 of the second segments 6, 8 along at least a portion of them, wherein the edges 9 along segment 90 (i.e., along the first segment 7) are not chamfered. For this purpose, it is advantageous that the glass element 5 has a chamfer 11 extending at least partially along at least one of the second segments 6, 8, wherein the chamfer 11 terminates at or before the boundary between the second segments 6, 8 and the adjacent first segment 7. In one embodiment, the chamfer 11 terminates at an inwardly skewed segment 91 of the edge 9, which in Figure 1b and Figure 3 This is also implemented in the examples. In these examples, the connection between two opposing segments 91 also forms the boundary between the first segment 7 and the second segments 6, 8. To avoid chamfering at the first segment 7, it is further preferred that the depth of the recess 93 along the edge 9 of the first segment 7 is greater than the depth of the chamfer 11 measured inward along the corresponding chamfered sides 50, 51. If in similar Figure 1b Viewed from the top view, chamfer 11 appears as a strip extending inward from edge 9. Therefore, the width of this strip is the depth of chamfer 11. (As seen from...) Figure 1b As can be seen, the width of the chamfer strip is slightly less than the depth of the recess 93.

[0037] In a preferred embodiment, the thickness of the flat glass element 5 in the second sections 6, 8 is 50µm to 300µm, preferably 70µm to 150µm. Typically, not limited to the glass thickness range given above, according to another preferred embodiment, the depth of the recess 93 is at least half the thickness of the flat glass element 5. This prevents facets, similar to chamfers at 45° angles to the sides 50, 51, from extending into the edges along the first section.

[0038] The example shown here has a single first segment 7 with reduced bending stiffness. However, depending on the folding method of the electronic display, it may be advantageous to provide multiple first segments. In particular, the flat glass element 5 may include at least two of the first segments 7, 71, 72, with second segments 6, 8, 61, 81 arranged between each of the at least two of the first segments 7, 71, 72. Figure 4a , 4b Figure 5 shows an example of this flat glass element 5.

[0039] In a preferred improvement of this embodiment, the flat glass element 5 includes three first segments. Figure 4a , Figure 4b and Figure 5In the example, the second segment 6 is arranged between the first segments 71 and 72, and the second segment 8 is arranged between the first segments 7 and 72. Furthermore, the width and / or stiffness-reducing structure of the first segments 7, 71, and 72 can differ. Preferably, not limited to this example, the first segment 7 arranged between two other first segments 71 and 72 can be wider than the other first segments 71 and 72. Similarly, the arrangement and size of the openings 18 can be adjusted to achieve the specific shape of the folded flat glass element 5. In particular, the thickness of the glass between the openings 19 can be adjusted to achieve the desired stiffness reduction. The arrangement of the relatively wide middle first segment 7 with three first segments 7, 71, and 72 can facilitate achieving a teardrop-like shape or bulging outwards from the folding area, thereby allowing the outer folded segments to come together closely. Figure 4a In the example, the stiffness reduction structure is provided through the opening (19), while Figure 4b In the example, the stiffness reduction structure is provided by the thinning section (19). According to Figure 4b The thinning portions of the three first segments 7, 71, and 72 can be positioned on two sides 50 and 51 of the glass element, but they can also be positioned on only one of sides 50 and 51, thereby forming a continuous unobstructed substrate for an OLED display or forming a continuous unobstructed outer surface of the cover glass.

[0040] Figure 5 It shows Figure 4a Or the glass element in the folded state of 4b. It can be seen that the alternating arrangement of flexible elements 71, 7, 72 and rigid second segments 61, 6, 8, 81 supports the bulging when folded.

[0041] Figures 6 to 9 The method steps for producing a flat glass element 5 having an opening 19 as described herein are illustrated. Based on the step of providing a glass plate 52 (having at least one recess 93 at its edge 9), the method includes the following steps: - By introducing multiple openings 19 into the first segment 7, the bending stiffness in the first segment 7 is reduced relative to the second segments 6, 8 adjacent to the first segment 7, wherein the first segment 7 is arranged between the two second segments and extends across the glass plate 52, such that the first segment 7 of the flat glass element 5 produced from the glass plate 52 terminates at a recess 93. Preferably, two recesses 93 are introduced on opposite sides of the edge 9 of the glass plate 52. Then, multiple openings 19 and / or thinning portions are introduced into the glass plate 52 to form the first segment 7 extending across the entire glass plate 52, such that the first segment 7 terminates at two oppositely arranged recesses 93.

[0042] The recess 93 can be formed, in particular, by removing glass at the edge 9 of the glass plate 52 along a section of the glass plate. However, in another embodiment, the glass plate 52 can be cut from a larger glass plate having the desired profile, the larger glass plate having at least one recess 93. For example, laser cutting would be a suitable technique, cutting the larger glass plate into the glass plate 52 in a single step. Figure 6 A glass plate 52 with two recesses 93 on opposite sides of its edge 9 is shown.

[0043] In the next step, edge 9 is chamfered. Figure 7 A glass plate 52 with chamfered edges 11 is shown. As shown, and preferably, all edges of the generally rectangular outline are chamfered. However, the chamfers 11 terminate at either the recess 93 or the inwardly sloping segment 91 of the edge 9. The recess 93 is deep enough that the edge segment 90 extending along the recess 93 is not chamfered.

[0044] According to a preferred embodiment, the opening 19 of the stiffness reduction structure is formed by the following steps: irradiating the glass plate 52 with a pulsed laser beam, so that the pulsed laser beam introduces filamentary defects in the glass, the filamentary defects being located on a predetermined contour of the opening 19 and distributed along the predetermined contour of the opening 19; then, etching the glass plate 5, so that the filamentary defects are widened and joined along the contour, thereby forming the opening 19. Figure 8 The image shows a glass plate 52 after being irradiated with a pulsed laser beam and having filamentary defects 25 introduced. From Figure 8 As can be seen, filamentous defects are introduced side by side along the contour of the opening to be formed. Figure 9A flat glass element 5 produced from a glass plate 52 by etching and forming an opening 19 is shown. The etching process along the filamentary defects 25 is much faster than that of the original glass. Therefore, during etching, the filamentary defects are widened to form channels with increased diameter. These channels eventually converge to form the edges of the opening 19. If the filamentary defects extend through the glass plate, a through opening is formed. This method of structuring glass is known from US2018 / 0215647A1, which is incorporated herein by reference in its entirety regarding the formation of the opening 19. Typically, etching can be performed using an alkaline etching bath, such as a KOH solution or a NaOH solution. Preferably, the pH of the etching bath is >12, for example, using a KOH solution with a concentration >4 mol / L, particularly >5 mol / L, more preferably >6 mol / L. Etching can be carried out at an etching bath temperature >70°C, for example >80°C, or >90°C to increase the etching rate. Due to the etching process, the flat glass element 5 preferably has an etched surface. This is advantageous because etching can increase the fracture strength of the glass. Furthermore, if additional layers, especially functional layers of electronic displays, are deposited on the sides 50 or 51, the adhesion of the deposited layers can be improved.

[0045] A suitable laser is a pulsed YAG laser, such as an Nd:YAG laser emitting at a wavelength of 1064 nm. The laser can advantageously operate in a so-called burst mode, in which a rapid series of pulses is emitted. The pulses within a burst typically have pulse lengths similar to those in single-pulse operation mode. As described in US 2018 / 0215647 A1, the burst frequency can range from 15 MHz to 90 MHz, for example from 20 MHz to 85 MHz, and for example, 50 MHz, and the number of pulses within a burst can range from 1 to 10 pulses, for example, 6 pulses.

[0046] For information on the method for producing the flat glass element 5 and the stiffness-reducing structure 70 with the opening 19 and its shape, please also refer to EP 3 936 485 A1, the entire contents of which are contained herein. For example, Figure 1 and Figure 9 The opening 19 shown is a rectangle with rounded ends. However, other shapes of opening 19 can also be used, for example, the opening may have two maximum width points spaced apart in the longitudinal direction, and there is an intermediate minimum width point between the two maximum width points.

[0047] Alternatively, the stiffness-reducing structure includes a thinned portion 20, which is preferably manufactured using a different process. The thinned portion 20 can be formed by photolithography etching, wherein an etch-stop mask is applied to a glass plate around a predetermined contour of the thinned portion 19, and the glass plate 5 is subsequently etched. Lithography etching typically includes the following steps: applying a photosensitive layer to the entire surface of the glass plate; exposing the photosensitive layer to light, typically ultraviolet light, through an optical mask to pattern the photosensitive layer; curing / hardening the exposed areas so that the pattern of the optical mask is transferred to the photosensitive layer; typically removing unexposed / soft areas of the photosensitive layer by dissolving it in a solvent. The entire glass plate 5 is then etched to form the thinned portion; subsequently, the cured / hardened mask is removed by heating or secondary ultraviolet exposure.

[0048] However, with opening 19, the preferred method of chamfering the edges after structuring is difficult to achieve because chamfering can easily damage the structure. To avoid this, the edges of the glass plate 52 can be machined first, and then the glass plate can be structured. This advantageously avoids the etched surface being scratched during the chamfering process, as the quality of the etched surface is generally better than that of the machined surface. However, the subsequent laser processing steps of the chamfered edges and the hinge structure of the first segment 7 present problems because there is no flat surface at the outer edge, making it difficult or even impossible to achieve the desired structuring quality.

[0049] However, if there is a recessed hinge area, two options are available: first, chamfering can be performed first, followed by laser structuring down to the edge; this process is unrestricted because the edge of the recessed area can be left unprocessed; second, the order can be reversed, with structuring performed first, followed by edge grinding. Therefore, the combination of the chamfered edge 9 and the recessed edge segment 90, especially with the etched surface of the opening 19, has particular advantages for improving the stability of the flat glass element 5.

[0050] In addition to the above, the recessed hinge area also has advantages in etching or chemical strengthening processes because the glass can be placed in the etching basket without the hinge area or the first section 7 contacting the bottom support of the holder.

[0051] In the example shown, the section 91 that tilts inward toward the recessed section 90 of the first section 7 is linear. Furthermore, this linear section is perpendicular to the adjacent edge 9 of the second sections 6, 8 of the glass element. However, this results in a sharp protrusion at the edge of the transition between the first and second sections, which may be easily damaged during the processing of the glass plate 52 or the flat glass element 5. To avoid this problem, the inwardly tilted section 91 could be slanted or rounded.

[0052] Figure 10 Examples of these variations are shown. Figure 10 In the figure, the two inwardly sloping sections 91 on the top of the flat glass element 5 are designed as rounded sections, while the other two inwardly sloping sections 91 are straight, but are inclined relative to the adjacent edges 9 along the respective second sections 6, 8, rather than perpendicular to them. Similarly, in both cases, preferably, as shown, the inwardly extending depth of the chamfer 11 is less than the depth of the corresponding recess 93. As can be seen from all the examples with chamfered edges, according to the preferred embodiment, the edge 9 is sloping inward toward the recessed section 90 of the edge 9 extending along the first section 7, wherein the edge 9 is also at least partially chamfered along the length of the inwardly sloping section 91. Therefore, the chamfer 11 can be designed to be close to the un-chamfered recessed edge portion.

[0053] Other methodological steps can be followed to complete the flat glass element 5. According to a particularly preferred embodiment, the flat glass element 5 is chemically strengthened. The aforementioned advantages of the recess 93 at the first section 7 also apply to the chemical strengthening process. The recessed edge section 90 avoids mechanical contact between the structured first section 7 and the components of the strengthening device. Chemical strengthening can be carried out, for example, by immersing and storing the flat glass plate 5 in a molten salt bath. Suitablely, a salt bath containing potassium nitrate (KNO3) can be used to remove Na from the glass. + Ion exchange is K + ion.

[0054] Figure 11 A cross-section through the chemically strengthened flat glass element 5 is shown. It is clear from the cross-sectional view that opening 19 is a through-hole, thereby connecting the sides 50, 51 of the flat glass element 5. The arrangement of opening 19 causes the structure of the glass retained in the first part 7 to form the web 21. In the example shown, a variation of the chamfer 11 is also implemented. Figures 7 to 9 As shown, chamfer 11 can be a facet. However, alternatively, chamfer 11 can be designed as a rounded shape, such as... Figure 11 As shown. Other designs can also be implemented, such as combinations of one or more facets with one or more rounded edges, or multiple adjacent facets.

[0055] Due to chemical strengthening, an ion exchange layer 27 is formed on all glass surfaces exposed to the salt bath. The ion exchange layer is shown as a shaded area extending inward from the glass surface toward the glass body 28. In a preferred embodiment, the depth of the ion exchange layer is at most 5 μm. The depth of the ion exchange layer 27 can be controlled by the temperature of the salt bath and the exposure time. The thin ion exchange layer 27 helps reduce the wrinkling effect caused by the relatively large specific surface area within the first segment 7. This is because the walls of the opening 19 provide additional surface area. As larger ions are deposited in the ion exchange layer 27, these surfaces tend to expand, and therefore, arching and wrinkling may occur in the first segment 7.

[0056] To form this low-DoL ion exchange layer 27 within the structured first segment 7, a multi-stage ion exchange process can be advantageously utilized. A two-step process is preferred. Typically, the ion exchange process can be improved by exposing the second segment to the ion exchange medium (e.g., especially a salt bath) for a longer period than the first segment 7. In this regard, the two-step process can be implemented by exposing the entire planar glass element 5 to the ion exchange medium in one step, and exposing only the second segment to the ion exchange medium in another step. The order of these steps is not related. For example, after strengthening the entire planar glass element 5, the first segment 5 can be covered so that only the second segments 6 and 8 are exposed and strengthened in subsequent steps. Conversely, the covering of the first segment can be removed after the first strengthening step, thus excluding the first segment 7 from chemical strengthening in that step. Furthermore, the second segment can be strengthened first in the first strengthening step, while the first segment is not immersed in the molten salt bath, and then the entire segment is strengthened in a subsequent second strengthening step.

[0057] After removing the covering and re-exposing, the entire flat glass element 5 is strengthened. In cases where there is more than one first segment 7 (as in the example of Figure 4), more steps can be utilized. Typically, the exposure time can be selected based on the porosity or specific surface area of ​​one or more first segments 7, 71, 72. For example, if the middle first segment 7 has a higher specific surface area than the other first segments 71, 72, a three-step strengthening method can be used. In this case, three different exposure times can be selected, with the middle first segment 7 having the shortest exposure time, the outer first segments 71, 72 having a medium exposure time, and the second segments 6, 8, 61, 81 having the longest exposure time.

[0058] As an improvement, in addition to the recessed hinge areas at the first section 7, bridging elements or bridging sections, which themselves constitute reinforcing elements, can be considered. The bridging sections can be specifically designed as removable supports. The bridging sections can be formed together with a stiffness-reducing structure including opening 19.

[0059] In particular, the process described above, which uses ultrashort laser pulses to introduce filamentary defects and then etch out the contours, can be advantageously utilized. The support or bridging segment can be designed to remain attached to the glass during etching and, possibly, during chemical strengthening. The bridging segment can then be removed, for example, during the assembly of the display stack. Therefore, in an improvement, the method includes structuring the glass plate 52 to form a bridging segment 13, which connects to the second segments 6, 8 and bridges a portion of the edge 9 of the glass plate 52. Specifically, in an improvement to the method of producing a flat glass element 5 for a carrier of an electronic display, a bridging segment is formed that bridges the first segment 7 and connects to the adjacent second segments 6, 8. In another embodiment, the bridging segment 13 may also be connected to the first segment 7. This particularly helps to stabilize the fragile structured hinge segment. However, this embodiment carries the risk that removing the bridging segment 13 from the first segment 7 by means of fracture could damage the structured hinge.

[0060] Typically, the bridging section is preferably connected to at least one of the second sections 6 and 8 and bridges at least a portion of the edge 9 of the flat glass element 5. Figure 13 An example of a glass element 5 with a detachable bridging section 13 is shown. Typically, as shown, the bridging section 13 can be located within a corresponding recess 93. Furthermore, as implemented in the depicted example, the outer edge of the bridging section 13 can be aligned with the edge 9 along at least one of the second sections 6, 8. Thus, the structuring of the glass element 5 can be achieved using a glass plate 52 having a rectangular shape with the same dimensions as the glass element, or by providing a glass plate 52 that already has edges 9 (in addition to subsequently formed sections 90, 91). Furthermore, as shown, the edge 9 is skewed inward toward the recessed section 90 of the edge 9 extending along the first section 7, wherein the bridging section 13 connects to the inwardly skewed section 91 of the edge 9. In this way, the mechanical connection is close to the flexible first section 7, thereby providing a stable and compact design.

[0061] The bridging section 13 helps stabilize the flexible glass and simplifies the handling and alignment during assembly. The bridging section not only maintains the flexibility of the flat glass element but also its length / width ratio to prevent stretching or compression of the flexible first section 7. Furthermore, the bridging section 13 can also serve as a clamping point during handling or as a support point in processes such as etching or chemical strengthening, so that the flat glass element 5 does not necessarily have to rest against a corresponding holder by its outer edge. After performing the above processes, the bridging section 13 can be removed (e.g., disconnected). To facilitate removal of the bridging section 13, it can advantageously be connected to the second sections 6, 8 via a weakening element 15, wherein the weakening element 15 is designed to be more prone to breakage than the bridging section 13. In a first embodiment, the weakening element 15 includes a web 16 with a reduced width relative to the bridging section 13. In the example shown, the bridging section is connected to the inwardly offset section 91 of the edge 9 via three webs 16. Alternatively or additionally, other weakening elements 15 can be utilized. According to alternative or additional embodiments, the weakening element 15 may include a thinned region with reduced glass thickness relative to the bridging section 13. For example, the web 16, compared to the bridging section 13, has not only a reduced width but also a reduced glass thickness.

[0062] Figure 13 It shows Figure 12 A magnified partial view is provided to illustrate other options for the weakening element 15. Typically, a weakening element may include one or more defects that reduce the glass's fracture strength, a region of altered refractive index relative to an adjacent region of the glass plate 5, or a region of reduced density relative to an adjacent region of the glass plate 5. In the example shown, a defect 17 is introduced at the junction between the web 16 and the edge (particularly, the inwardly skewed segment 91 of the edge). These defects 17 may constitute regions of altered density or refractive index. In a preferred improvement, the defects 17 are introduced using a short-pulse laser, similar to the laser used to process the contour of the opening 19, so that these defects 17 can be shaped into filamentary defects.

[0063] The bridging section 13 helps stabilize the flexible glass and simplifies the handling and alignment during assembly. The bridging section 13 not only stabilizes the flexibility of the flat glass element 5 but also its length / width ratio (tension or compression of the flexible hinge). Furthermore, the bridging section can also serve as a clamping point during operation or a support point in processes such as etching or chemical strengthening, so that the glass plate does not necessarily have to rest its outer edge against the corresponding holder. Therefore, according to one embodiment, during the processing of the flat glass element 5, the flat glass element 5 is clamped and secured at the bridging section 13. This processing may include steps such as chemical strengthening or coating.

[0064] After processing (e.g., coating steps and / or chemical strengthening), the (fractured) bridging section 13 can be removed, retaining only the edges showing a small area with the fractured surface, while the majority of the edges have an etched surface structure. For illustration, Figure 14 It shows something similar to Figure 13 The enlarged section of the flat glass element 5, however, is removed by breaking the bridging section 13 from the flat glass element 5. Most of the edge 9 has an etched surface 29. Figure 14 The surface is represented by a dotted pattern. Preferably, an etching process is used to form a surface structure including a hemispherical depression, as described in US 2018 / 0215647A1, the contents of which regarding the structuring and etching process and the resulting surface structure are incorporated herein by reference. By fracturing the web 16, the bridging section 13 is removed, leaving a small fracture surface 30 with a shape corresponding to the cross-section of the web 13. Similarly structured glass elements are also known in WO 2022 / 268585 A1, the contents of which regarding surface morphology and design are incorporated herein by reference. Thus, according to this improvement, the flat glass element 5 has an edge 9 including an etched surface 29 and a fracture surface 30, wherein the etched surface 29 and the fracture surface 30 are arranged adjacent to each other along the edge 9. Since the connecting web 16 is narrow, the fracture surface 30 preferably has only a small surface portion of the edge surface. Preferably, the fracture surface covers less than 10%, more preferably less than 5%, and even more preferably less than 1% of the edge surface portion.

[0065] Alternatively, the bridging section 13 may also be designed such that the bridging section 13 can be removed during the etching process to obtain a fully etched outer edge, or that the bridging section 13 can be removed during chemical strengthening (e.g., by causing internal stress that leads to fracture of the connecting web or defect).

[0066] Figure 15 It shows Figure 12 Variations of the embodiment. According to this embodiment, generally, and not limited to the specific example shown, the bridging section 13 has a protrusion 32 that bulges outward beyond the edge 9 along the second sections 6, 8. Preferably, both opposing bridging sections 13 have such a protrusion. The protrusion 32 can facilitate further handling of the flat glass element 5, and in particular, facilitate clamping the element at the bridging section 13.

[0067] exist Figure 12 and 15 In one embodiment, the bridging section 13 is small and is mainly arranged within the recess 93. However, a frame-like structure can also be used. Figure 16An example of a flat glass element 5 is shown, which is surrounded by a bridging section 13 forming a frame 14 and connected to the bridging section 13 by a web 16. Figure 12 , Figure 15 and Figure 16 The embodiments can also be understood as intermediate products 35 for producing flat glass elements 5 for carriers of electronic displays. Therefore, without limitation to specific examples or embodiments, intermediate products 35 for producing flat glass elements 5 are provided, comprising structured glass plates 52. Glass plate 52 includes flat glass elements 5 as described herein and bridging sections 13. The flat glass element 5 is connected to the bridging sections 13 via weakening elements 15 (particularly including webs 16), bridging a first section 7 at the connection with the bridging sections 13 to stabilize the first section 7, wherein the bridging sections 13 are detachable from the flat glass element 5.

[0068] In another embodiment, the flat glass element 5 or intermediate product 35 may alternatively or additionally include a removable support that facilitates operation (e.g., by clamping and / or holding the flat glass element 5 during processing), also as referenced. Figure 15 As described. Figure 17 An example of a flat glass element 5 or intermediate product 35 is shown, having at least one support detachably connected to the edge 9 of the flat glass element 5. Similar to the bridging section 13 described herein, one or more supports 18 and the flat glass element 5 are formed as an integral structure from the same glass sheet. In the example shown, a weakening structure in the form of a row of defects 17 conforming to the contour of the edge 9 is considered, detachably connecting the supports 18 to the glass element 5. Of course, other elements, such as a web 16, can be used. Thus, the supports 18 are similar to the bridging section 13, but the supports 18 do not necessarily bridge the first section 7.

[0069] Figure 18 A cross-section of a first variant of the cover 1 of an electronic display having a flat glass element 5 as described herein is shown, wherein the reduced stiffness pattern includes an opening 19. The opening 19 in the first segment 7 is filled with a thermoplastic elastomer 41, preferably thermoplastic polyurethane. The filling with thermoplastic elastomer 41 forms a closed surface on the side 50 for the purpose of covering the electronic display.

[0070] Thermoplastic elastomer 41 can have the same refractive index n as a flat glass element. dThis is to avoid any reflection at the interface between the flat glass element 5 and the thermoplastic elastomer 41. Typically, the thermoplastic elastomer 41 helps maintain the flexibility of the first segment 7. Furthermore, the thermoplastic elastomer 41 may also cover the edge segments along the first segment 7 and / or at least partially fill the recess 93, thereby further protecting the brittle edge segments in the flexible first segment 7.

[0071] An alternative or additional option is to fill the opening 19 with thermoplastic elastomer 41 and cover the entire sides 50, 51 of the glass element.

[0072] Figure 19 A cross-section of a second variant of the cover 1 of an electronic display having a flat glass element 5 as described herein is shown, wherein the reduced stiffness pattern includes a thinning portion 20. The thinning portion 20 in the first section 7 is filled with a thermoplastic elastomer 41, preferably thermoplastic polyurethane. The filling with the thermoplastic elastomer 41 forms a closed surface on the side 50 and a non-blocking glass surface on the opposite side 50. The thermoplastic elastomer 41 may have the same refractive index n as the flat glass element. d This is to avoid any reflection at the interface between the flat glass element 5 and the thermoplastic elastomer 41. Typically, the thermoplastic elastomer 41 helps maintain the flexibility of the first segment 7. Furthermore, the thermoplastic elastomer 41 can also cover the edge segments along the first segment 7 and / or at least partially fill the recess 93, thereby further protecting the brittle edge segments in the flexible first segment 7. An alternative or additional option is to fill the thinned portion 20 with the thermoplastic elastomer 41 and cover the entire side 51 of the glass element.

[0073] List of reference numerals

Claims

1. A flat glass element (5) for a cover (1) of an electronic display (3), wherein the flat glass element (5) has two opposing sides (50, 51), wherein the glass of the glass element (5) has a varying bending stiffness along at least one line across the glass element (5), the varying bending stiffness being provided by at least one first segment (7), the bending stiffness of the at least one first segment (7) being reduced relative to the bending stiffness of a second segment (6, 8) adjacent to the at least one first segment, such that the glass element (5) is able to bend at the first segment (7), the reduced stiffness of the first segment (7) being achieved by a stiffness-reducing pattern (70), the pattern (70) including an arrangement of openings (19) and / or thinning portions (20), and wherein the edge (9) of the glass element (5) is recessed inward at the first segment (7).

2. The flat glass element (5) according to the preceding claim, characterized in that, It has at least one of the following characteristics: - The thickness of the second section is 50µm to 300µm, preferably 70µm to 150µm; - Chamfer the edge (9) along at least a portion of the second section (6, 8); - The stiffness-reduced pattern (70) includes an arrangement of openings (19) in which the edges (9) along the first segment (7) are not chamfered; - The stiffness-reduced pattern (70) includes an arrangement of thinned portions (20) but does not include an opening (19), wherein the edge (9) along the first segment (7) is chamfered; - The glass element (5) has a chamfer (11) extending at least partially along at least one of the second segments (6, 8), wherein the chamfer (11) terminates at or before the boundary between the second segment (6, 8) and the adjacent first segment (7); - The depth of the edge (9) along the recess (93) of the first section (7) is greater than the depth of the chamfer (11) inward along the side (50, 51).

3. The flat glass element (5) according to any one of the preceding two claims, characterized in that, The edge (9) is skewed inward toward the recessed section (90) of the edge (9), wherein the edge (9) is at least partially chamfered along the length of the inwardly skewed section (91), wherein preferably, the inwardly skewed section (91) is rounded or sloping relative to the adjacent edge (9) along the second section (6, 8).

4. The flat glass element (5) according to any one of the preceding claims, comprising at least one detachable bridging section (13) connected to at least one of the second sections (6, 8) and bridging at least a portion of the edge (9) of the flat glass element (5).

5. The flat glass element (5) according to the preceding claim, comprising at least one of the following features: - The bridging section (13) is connected to two second sections (6, 8) and is bridged or connected to the first section (7). - The edge (9) is skewed inward toward the recessed section (90) of the edge (9) extending along the first section (7), wherein the bridging section (13) is connected to the inwardly skewed section (91) of the edge (9). - The bridging section (13) has a protrusion (32) that bulges outward beyond the edge (9) along the second section (6, 8).

6. The flat glass element (5) according to claim 4 or 5, wherein the bridging segment (13) is connected to the first segment and / or the second segment (6, 8) via a weakening element (15), the weakening element (15) being designed to break more easily than the bridging segment (13) and the second segment (6, 8). The weakening element (15) includes at least one of the following elements: - The web (16) has a reduced width relative to the bridging section (13). - One or more defects that reduce the fracture strength of the glass (17). -Thinning region with reduced thickness relative to the bridging section (13), -The region where the refractive index changes relative to the adjacent region of the glass plate (5), - A region where the density decreases relative to the adjacent region of the glass plate (5).

7. The flat glass element (5) according to any one of the preceding claims has at least one of the following features: -The opening (19) forms a through hole in the glass element (5), - The thinning portion (20) forms a blind hole in the glass element, wherein the remaining glass thickness is less than 70µm, preferably less than 50µm, more preferably less than 40µm and greater than 10µm, preferably greater than 20µm. - The thinning portion (20) has an elongated shape, preferably a groove shape, with a width of 20µm to 300µm, preferably 50µm to 200µm, and the distance between the thinning portions is 20µm to 300µm, preferably 50µm to 200µm; - The thinning portion (20) has an elongated shape, preferably a groove shape, with a length of 500µm until it covers the entire width of the first section (7); - The edge (9) within the first section (7) is blocked by the opening (19) or the thinning portion (20) of the stiffness-reducing structure; -The glass element (5) has an etched surface; - The first section (7) extends across the entire flat glass element (5) such that the first section (7) terminates at the edge (9) of the opposite side of the flat glass element (5). - The depth of the recess (93) is at least half the thickness of the flat glass element (5); - The flat glass element (5) includes at least two first sections (7, 71, 72), wherein a second section (6, 8, 61, 81) is provided between the two first sections (7, 71, 72). - At least one bracket (18) is detachably connected to the edge (9) of the glass element, the bracket (18) and the flat glass element (5) being integrally formed.

8. The flat glass element (5) according to any one of the preceding claims, wherein the flat glass element (5) is chemically strengthened and includes at least one of the following features: - Chemical enhancement is achieved through an ion exchange layer, wherein the depth of the ion exchange layer is at most 5µm. - Compared to one of the segments in the second segment (6, 8), the ion exchange layer of the first segment (7) has a smaller depth.

9. A flat glass element (5) according to any one of the preceding claims, wherein the flat glass element (5) has an edge (9) comprising an etched surface (29) and a fractured surface (30), wherein the etched surface (29) and the fractured surface (30) are arranged to be adjacent to each other along the edge (9).

10. An intermediate product (35) for producing a flat glass element (5) according to any one of the preceding claims, comprising a structured glass plate (52) including the flat glass element (5) and a bridging section (13), the flat glass element (5) being connected to the bridging section (13) by a weakening element (15), the weakening element particularly including a web (16) wherein a connection with the bridging section (13) bridges the first section (7) to fix its length and is preferably connected to the first section (7) to protect the first section (7) from breakage, wherein the bridging section (13) is detachable from the flat glass element (5).

11. A method for producing a flat glass element (5) for a carrier (1) of an electronic display (3), the method comprising the steps of: - Provide a glass plate (52) having at least one recess (93) at its edge, wherein the recess (93) is formed, in particular by removing glass at the edge (9) of the glass plate (52) along a section of the glass plate (52). - By introducing multiple openings (19) or thinning portions (20) in the first section (7) to reduce the bending stiffness of the first section (7), the first section (7) is arranged between two second sections (6, 8) adjacent to the first section (7), the first section (7) extends across the glass plate (52) such that the first section (7) of the flat glass element (5) produced by the glass plate (52) terminates at the recess (93).

12. The method according to any one of the preceding claims, wherein two recesses (93) are introduced on opposite sides of the edge (9) of the glass plate (52), and wherein the plurality of openings (19) or thinning portions (20) are introduced into the glass plate (52) to form a first segment (7) extending across the entire glass plate (52), such that the first segment (7) terminates at the two oppositely arranged recesses (93).

13. The method according to the preceding claim further includes chamfering at least a portion of the edge of the glass plate (90) such that the chamfer (11) terminates at or before the recess (93), wherein the chamfering may be performed before or after the plurality of openings (19) are introduced into the first section.

14. The method according to any one of the preceding claims, wherein the opening (19) is formed by the following steps: irradiating the glass plate (52) with a pulsed laser beam such that the pulsed laser beam introduces filamentary defects in the glass, the filamentary defects being located on a predetermined contour of the opening (19) and distributed along the contour of the opening (19); and wherein the glass plate (5) is etched such that the filamentary defects are widened and joined along the contour, thereby forming the opening (19). And / or, wherein the thinned portion (20) is formed by the following steps: applying an etching stop mask to the glass plate (5) by photolithography, the mask being located on a predetermined contour of the thinned portion (19), and wherein the glass plate (5) is etched to form the thinned portion (20).

15. The method according to any one of the preceding claims, the method comprising structuring the glass plate (52) to form bridging sections (13). The bridging section (13) bridges a portion of the edge (9) of the glass plate (52) and connects to the second section (6, 8), and also bridges or connects to the first section (7).

16. The method according to the preceding claim, wherein during the processing of the flat glass element (5), the flat glass element (5) is clamped and fixed at the bridging section (13).

17. The method according to any one of the preceding two claims, wherein the bridging segment (13) is formed by the following steps: - The glass plate (52) is irradiated with a pulsed laser beam, which introduces filamentary defects into the glass, the filamentary defects being located on and distributed along a predetermined contour of the bridging section (13), and wherein the glass plate (5) is etched, such that the filamentary defects are widened and joined along the contour, thereby forming the bridging section (13). - and / or, by photolithography, an etching stop mask is applied to the glass plate (5), the mask being located on a predetermined contour of the thinned portion (19), and wherein the glass plate (5) is etched to form a bridging segment (13).

18. The method according to any one of the preceding claims further includes chemically strengthening the flat glass element (5).

19. The method according to the preceding claims, wherein the second segment (6, 8) is exposed to the ion exchange medium for a longer period than the first segment (7).

20. A cover (1) for an electronic display (3) comprising a flat glass element (5) according to any one of claims 1 to 10 or a flat glass element (5) produced by the method according to any one of claims 12 to 19.

21. The cover (1) according to the preceding claim has at least one of the following features: - A thermoplastic elastomer 41 that fills the opening (19) and / or thinning portion (20) in the first segment (7) of the flat glass element (5), wherein the refractive index n of the thermoplastic elastomer 41 is... d It has the same refractive index as the flat glass element; - Polymer material (43) fills the opening (19) and / or thinning portion (20) in the first section (7) and also covers one side (51) of the flat glass element (5).

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