WO2023284959A1

WO2023284959A1 - Display assembly for foldable electronic apparatus

Info

Publication number: WO2023284959A1
Application number: PCT/EP2021/069679
Authority: WO
Inventors: Nadja LONNROTH
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2021-07-15
Filing date: 2021-07-15
Publication date: 2023-01-19
Also published as: CN117222962A

Abstract

A display assembly (1) for an electronic apparatus (2) comprising a flexible display structure (3) configured to be curved around a main axis (A1), and a matrix (5) superimposed onto said flexible display structure (3) and comprising a first material. The matrix (5) comprises a grating structure (6) arranged adjacent said main axis (A1) of said flexible structure (3), and said grating structure (6) comprises a second material having a lower density than said first material. The first material may comprise aluminosilicate glass, fused silica glass, or any suitable and transparent multicomponent glass. The grating structure (6) may be formed by a plurality of elongated channels (6a), each elongated channel (6a) extending along a center axis (A2), the center axis (A2) extending perpendicular or parallel to said main axis (A1).

Description

DISPLAY ASSEMBLY FOR FOLDABLE ELECTRONIC APPARATUS

TECHNICAL FIELD

The disclosure relates to display assembly for an electronic apparatus comprising a flexible display structure configured to be curved around a main axis.

BACKGROUND

A foldable apparatus design enables usage of large screens while still allowing the apparatus to fit into a pocket. However, foldable displays can experience problems with a visible bending area bump being created at the hinge. Such a bump will form when a polymer is used as the cover material, which affects the user’s viewing experience by distorting the pixels and the image.

Current solutions include using polymer only, i.e., no glass material. This ensures sufficient bendability and foldability even for rather small bending radiuses. Nevertheless, polymers undergo creep when being bent for an extended period of time, thus, the bend will be visible at the hinge area when the device is unfolded. Furthermore, achieving a scratch-proof surface is a complex problem since using a hard coating on a softer polymer is challenging in itself, and since using a soft, self-healing coating gives a different feel to the surface.

Another solution comprises using very thin glass with a thickness of, e.g., 30 pm. The thinness of the glass makes the film flexible enough to bend to the needed radius. However, such a thin and hard glass film is extremely fragile and will be punctured by the smallest force, leading to shattering of the glass. When the glass is chemically strengthened, the strengthened layer cannot be more than a few pm thick due to force balance, which is insufficient to provide enough protection for the film. Furthermore, attempts have been made at making the hinge area glass thinner in order to enable bending to a small radius. This will, nevertheless, make the bending area very vulnerable to breaking since, as mentioned above, a thin and hard glass film is extremely fragile.

Hence, there is a need for providing an improved display assembly that is suitable for bending, folding, and sliding displays.

SUMMARY

It is an object to provide an improved display assembly. The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description, and the figures.

According to a first aspect, there is provided a display assembly for an electronic apparatus comprising a flexible display structure configured to be curved around a main axis, and a matrix superimposed onto the flexible display structure and comprising a first material, wherein the matrix comprises a grating structure arranged adjacent the main axis of the flexible structure, wherein the grating structure comprises a second material having a lower density than the first material.

By decreasing the Young’s modulus in a section of the matrix, i.e. reducing the tensile stiffness in that section, the matrix becomes more flexible in that section only. This allows the display assembly to bend while providing a relatively thick matrix, the thicker the matrix the more resistant it is to impact. Furthermore, by reducing the stiffness in the hinge area of the electronic apparatus, there is a decreased risk of delamination of the display assembly layers. Additionally, the matrix can form a cover structure that is resistant to scratching.

In a possible implementation form of the first aspect, the grating structure extends through an intermediate section of the matrix, which section is configured to be arranged adjacent the main axis of the flexible display structure when the flexible display structure is being curved. By changing the internal mechanical properties of a section of the matrix, making it less dense and hence more flexible, the matrix can be bent at this section, while still maintaining its original properties, i.e., resistance to scratching and impact, at, e.g., the surfaces of the matrix.

In a further possible implementation form of the first aspect the grating structure is subjected to tensile stress when the flexible display structure is being curved, the grating structure facilitating curving the display assembly in the area of tensile stress.

In a further possible implementation form of the first aspect the flexible display structure is configured to curve around the main axis by bending around the main axis, folding around the main axis, or/and sliding across the main axis in directions perpendicular to the main axis, facilitating a solution which can be applied on different curving configurations.

In a further possible implementation form of the first aspect the first material comprises aluminosilicate glass and/or fused silica glass. Such a solution allows for a display assembly that can be bent without a visible bump eventually forming in the bending area.

In a further possible implementation form of the first aspect, the first material comprises a multicomponent glass.

In a further possible implementation form of the first aspect, the second material comprises air, facilitating a simple solution as lightweight as possible.

In a further possible implementation form of the first aspect, the grating structure is formed by a plurality of elongated channels, each channel comprising a plurality of nanostructures, allowing a volume of material to be penetrated by the grating structure and the properties of the grating structure, and hence the matrix, to vary within the grating structure.

In a further possible implementation form of the first, the channels are arranged periodically in the section such that the center axes of the channels extend in parallel and each channel is separated from adjacent channels by the first material, providing at the same time stability and flexibility.

In a further possible implementation form of the first aspect, each elongated channel extends along a center axis, the center axis extending perpendicular or parallel to the main axis, simplifying manufacture while still providing the desired flexibility.

In a further possible implementation form of the first aspect, the plurality of nanostructures of the channel are recesses formed in a surface of the channel, the nanostructures being arranged along the center axis of the channel.

In a further possible implementation form of the first aspect, the nanostructures of the channel extend at an angle to a center axis of the channel, allowing the properties of the grating structure to be adapted to a specific configuration.

In a further possible implementation form of the first aspect, the plurality of nanostructures of the channel extend at least partially around an inner circumference of the channel and at an angle >0° to the center axis of the channel.

In a further possible implementation form of the first aspect, at least a first center axes of a first channel extend in parallel with a second center axes of a second channel, and the nanostructures of the first channel extend at a different angle to the center axis than the nanostructures of the second channel, allowing the properties of the grating structure, and hence the matrix, to vary within the grating structure.

According to a second aspect, there is provided an electronic apparatus comprising a first housing section, a second housing section, and a display assembly according to the above, wherein at least a first part of the display assembly is connected to the first housing section, a second part of the display assembly is connected to the second housing section, and an intermediate section of the display assembly is configured to be curved around the main axis when the second housing section is moved in relation to the first housing section. By decreasing the Young’s modulus in a section of the display assembly, i.e. reducing the tensile stiffness in that section, the display assembly becomes more flexible in that section only. This allows the display assembly to be bend while still being resistant to impact. Furthermore, by reducing the stiffness in the hinge area of the electronic apparatus, there is a decreased risk of delamination of the display assembly layers.

In a possible implementation form of the second aspect, the movement of the second housing section comprises the second housing section pivoting in relation to the first housing section around the main axis, or the second housing section sliding in relation to the first housing section in directions perpendicular to the main axis, allowing the solution to be applied on different apparatus configurations.

According to a third aspect, there is provided a method of manufacturing a display assembly, the method comprising the steps of providing a matrix comprising a first material, writing a grating structure through a section of the matrix by means of femtosecond laser machining, and applying the matrix onto a flexible display structure configured to be curved around a main axis, such that the grating structure is arranged adjacent the main axis of the flexible display structure.

By decreasing the Young’s modulus in a section of the matrix, i.e. reducing the tensile stiffness in that section, the matrix becomes more flexible in that section only. This allows the display assembly to be bend while providing a relatively thick matrix, the thicker the matrix the more resistant it is to impact. Furthermore, by reducing the stiffness in the hinge area of the electronic apparatus, there is a decreased risk of delamination of the display assembly layers. Additionally, the matrix can form a cover structure that is resistant to scratching.

In a possible implementation form of the third aspect, the method further comprises a last step of applying a coating layer onto the matrix, providing further protection to the matrix and display assembly. These and other aspects will be apparent from the embodiment(s) described below.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed portion of the present disclosure, the aspects, embodiments, and implementations will be explained in more detail with reference to the example embodiments shown in the drawings, in which:

Fig. 1 shows a schematic top view of an electronic apparatus in accordance with an example of the embodiments of the disclosure;

Fig. 2 shows a schematic side view of a display assembly in accordance with an example of the embodiments of the disclosure;

Fig. 3 shows a schematic illustration of a grating structure of a display assembly in accordance with an example of the embodiments of the disclosure;

Figs. 4a and 4b show schematic illustrations of grating structures with nanostructures in accordance with examples of the embodiments of the disclosure.

DETAILED DESCRIPTION

Fig. 1 illustrates an electronic apparatus 2 comprising a first housing section 7a, a second housing section 7b, and a display assembly 1 described in more detail below, wherein at least a first part of the display assembly 1 is connected to the first housing section 7a, a second part of the display assembly 1 is connected to the second housing section 7b, and an intermediate section of the display assembly 1 is configured to be curved around the main axis A1 when the second housing section 7b is or has been moved in relation to the first housing section 7a. The movement of the second housing section 7b may comprise the second housing section 7b pivoting in relation to the first housing section 7a around the main axis A1 , such that the electronic apparatus 2 is foldable and unfoldable, e.g., between a smartphone and a tablet. The second housing section 7b may also be arranged to slide in relation to the first housing section 7a in directions Dl, D2 perpendicular to the main axis Al, such that the electronic apparatus 2, e.g., expands by sliding the second housing section 7b out of the first housing section 7a.

A display assembly 1 for an electronic apparatus 2 comprises a flexible display structure 3 configured to be curved around a main axis Al , and a matrix 5 superimposed onto the flexible display structure 3 and comprising a first material, wherein the matrix 5 comprises a grating structure 6 arranged adjacent the main axis Al of the flexible structure 3, wherein the grating structure 6 comprises a second material having a lower density than the first material.

Fig. 2 shows the display assembly 1 schematically. The display assembly 1 comprises a flexible display structure 3 that is configured to be curved around a main axis Al. The flexible display structure 3 may comprise any suitable and required number of layers, such as a touch panel, polarizers, diffusers, color fdters, or adhesive layers.

The flexible display structure 3 may be configured to curve around the main axis Al by bending around the main axis Al, fold around the main axis Al, or/and slide across the main axis Al in directions Dl, D2 perpendicular to the main axis Al. The flexible display structure 3 may, e.g., be configured to simultaneously curve around the main axis Al and slide perpendicularly across the main axis Al, depending on the configuration of the electronic apparatus 2.

The display assembly 1 further comprises a matrix 5 superimposed onto the flexible display structure 3. As a section of the flexible display structure 3 bends, the matrix 5 bends along with it. The matrix 5 is configured to form a cover structure 4 superimposed onto the display structure 3 in order to provide protection against scratching and impact.

The matrix 5 comprises a first material. The first material may comprise aluminosilicate glass, fused silica glass, or any suitable transparent, multicomponent glass. The first material may be chemically strengthened.

The matrix 5 furthermore comprises a grating structure 6 arranged adjacent the main axis A1 of the flexible structure 3, i.e., the grating structure 6 extends through a volume of the matrix 5 which may be, at some point, subjected to bending. The edges of the matrix 5, arranged along opposite long sides of the first housing section 7a and the second housing section 7b, are, for example, most likely not subject to bending regardless of which position the electronic apparatus 2 is in.

In other words, the grating structure 6 may extend through an intermediate section 5a of the matrix 5, as suggested in Figs. 1 and 2, which section 5a is configured to be arranged adjacent the main axis A1 of the flexible display structure 3 when the flexible display structure 3 is being curved. The section 5a may be a volume extending partially through the matrix 5 in directions Dl, D2 perpendicular to the main axis A1 and partially through the matrix 5 in a direction D3, D4 perpendicular to directions Dl, D2 and the main axis Al. For example, a top and bottom layer of the matrix 5, seen in direction D3, D4, having a thickness of 10 pm may be left without grating structure 6 when the matrix 5 in total is 70 pm thick, leaving section 5a 50 pm thick.

When the electronic apparatus 2 has a foldable configuration, the section 5a is usually a specific volume that does not change or move, i.e., always located at the same place. When the electronic apparatus 2 has a sliding or configuration, the section 5a is somewhat moveable, as the electronic apparatus 2 expands or decreases in size, the display assembly 1 slides across the main axis Al and, hence, the section 5a moves as well relative the main axis Al. The section 5a may, in other words, be a section subjected to tensile stress when the flexible display structure 3 is being curved. More specifically, the grating structure 6 may be subjected to tensile stress when the flexible display structure 3 is being curved. The grating structure 6 comprises a second material that has a lower density than the first material. The second material may comprise air, i.e., such that the grating structure 6 is a hollow structure. However, the grating structure 6 may be filled with any suitable material.

The grating structure 6 may be formed by a plurality of elongated channels 6a, as shown schematically in Fig. 3. The channels 6a may have elliptical cross-sections, however any suitable and technically achievable cross-section is possible.

The channels 6a may be arranged periodically in section 5a such that each channel 6a is separated from adjacent channels 6a by the first material. Each elongated channel 6a may extend along a center axis A2, as shown in Figs. 4a and 4b, the center axis A2 extending perpendicular to or parallel with the main axis A1. Nevertheless, the channel 6a layout depends on several factors such as the actual matrix thickness, matrix chemistry, the needed radius of curvature, and chosen manufacturing process parameters.

Each channel 6a may comprise a plurality of nanostructures 6b, i.e. nanogratings, as shown schematically in Figs. 4a and 4b. Each nanostructure 6b forms a recess in the interior surface of the channels 6, such that the plurality of nanostructures 6b form periodic recesses having sizes in the nanoscale, i.e. the width of a nanostructure 6b is significantly smaller than the width of the channel 6a. The nanostructures 6b form recesses which may extend at an angle a to a center axis A2 of the channel, as suggested in Fig. 4a. In one embodiment, the plurality of nanostructures 6b extend at least partially around the inner circumference of the channel 6a and at an angle >0° to the center axis A2 of the channel 6a.

The nanostructures 6b form any suitable textured pattern, or ripples, in the surface of the channel 6a. The nanostructures 6b comprise the same material as the channels 6a, i.e. the second material. In other words, the channels 6a as well as the nanostructures 6b may be formed in the first material, e.g. aluminosilicate glass, such that the channels 6a and the nanostructures 6b together form hollow structures filled with air. The actual configuration of the nanostructure depends on the interaction between the glass material, i.e. the first material, and the laser used to form the grating structure 6. Furthermore, the dimensions, directions, and angles can be changed with laser power, processing speed, and light properties.

At least a first center axes A2 of a first channel 6a extend in parallel with a second center axes A2 of a second channel, and the nanostructures 6b of the first channel 6a extend at a different angle than the nanostructures 6b of the second channel, as suggested in Figs. 4a and 4b. The channels 6a may be arranged such that every second channel 6a has a first set of nanostructures 6b, and the other channels 6a have a second set of nanostructures 6b. Nevertheless, any number of different sets of nanostructures 6b is possible.

The present invention further relates to a method of manufacturing the display assembly 1, the method comprising the steps of providing a matrix 5 comprising a first material and writing a grating structure 6 through a section of the matrix 5 by means of femtosecond laser machining. Femtosecond laser machining allows creation of the smallest structures possible using light. The channels 6a, i.e., laser tracks, may be written in a direction which is optimal compared for the curving of the display assembly 1, and the polarization of the laser beam may be also optimized to form nanostructures 6b at the angle resulting in the largest change to the Young’s modulus, e.g., from 75 GPa to 36 GPa. For each matrix 5 material type it has to be determined what laser parameters such as energy, pulse duration, translation speed and polarization give the best results. As an example, the laser writing parameters may be 50 fs, 250 nJ, 120 kHz, 1 mm/s, polarization 90° across the writing direction.

Subsequently, the matrix 5 is applied onto the flexible display structure 3, that is configured to be curved around the main axis Al, such that the grating structure 6 is arranged adjacent the main axis Al of the flexible display structure 3. The method may further comprise a last step of applying a coating layer 8, of preferably hard coating, onto the matrix 5.

The various aspects and implementations have been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed subject-matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

The reference signs used in the claims shall not be construed as limiting the scope. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this disclosure. As used in the description, the terms “horizontal”, “vertical”, “left”, “right”, “up” and “down”, as well as adjectival and adverbial derivatives thereof (e.g., “horizontally”, “rightwardly”, “upwardly”, etc.), simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader. Similarly, the terms “inwardly” and “outwardly” generally refer to the orientation of a surface relative to its axis of elongation, or axis of rotation, as appropriate.

Claims

1. A display assembly (1) for an electronic apparatus (2) comprising

-a flexible display structure (3) configured to be curved around a main axis (Al); and -a matrix (5) superimposed onto said flexible display structure (3) and comprising a first material, wherein the matrix (5) comprises a grating structure (6) arranged adjacent said main axis (Al) of said flexible structure (3), wherein said grating structure (6) comprises a second material having a lower density than said first material.

2. The display assembly (1) according to claim 1, wherein said grating structure (6) extends through an intermediate section (5a) of said matrix (5), which is at least partially arranged adjacent said main axis (Al) of said flexible display structure (3).

3. The display assembly (1) according to claim 1 or 2, wherein said grating structure (6) is subjected to tensile stress when said flexible display structure (3) is being curved.

4. The display assembly (1) according to any one of the previous claims, wherein the flexible display structure (3) is configured to curve around said main axis (Al) by bending around said main axis (Al), folding around said main axis (Al), or/and sliding across said main axis (Al) in directions (Dl, D2) perpendicular to said main axis (Al).

5. The display assembly (1) according to any one of the previous claims, wherein said first material comprises aluminosilicate glass and/or fused silica glass.

6. The display assembly (1) according to any one of the previous claims wherein said second material comprises air.

7. The display assembly (1) according to any one of the previous claims wherein said grating structure (6) is formed by a plurality of elongated channels (6a), each channel (6a) comprising a plurality of nanostructures (6b).

8. The display assembly (1) according to claim 7, wherein said channels (6a) are arranged periodically in said section (5a) such that center axes (A2) of said channels (6a) extend in parallel and each channel (6a) is separated from adjacent channels (6a) by said first material.

9. The display assembly (1) according to claim 7 or 8, wherein said plurality of nanostructures (6b) of said channel (6a) are recesses formed in a surface of said channel (6a), said nanostructures (6b) being arranged along the center axis (A2) of said channel (6a).

10. The display assembly (1) according to claim 9, wherein said plurality of nanostructures (6b) of said channel (6a) extend at least partially around an inner circumference of said channel (6a) and at an angle (a) >0° to said center axis (A2) of said channel (6a).

11. The display assembly (1) according to claim 9 or 10, wherein at least a first center axes (A2) of a first channel (6a) extend in parallel with a second center axes (A2) of a second channel, and the nanostructures (6b) of said first channel (6a) extend at a different angle (a) to said center axis (A2) than the nanostructures (6b) of said second channel.

12. An electronic apparatus (2) comprising a first housing section (7a), a second housing section (7b), and a display assembly (1) according to any one of claims 1 to 10, wherein at least a first part of said display assembly (1) is connected to said first housing section (7a), a second part of said display assembly (1 ) is connected to said second housing section (7b), and an intermediate section of said display assembly (1) is configured to be curved around the main axis (Al) when said second housing section (7b) is moved in relation to said first housing section (7a).

13. The electronic apparatus (2) according to claim 12, wherein the movement of said second housing section (7b) comprises said second housing section (7b) pivoting in relation to said first housing section (7a) around said main axis (Al), or said second housing section (7b) sliding in relation to said first housing section (7a) in directions (Dl, D2) perpendicular to said main axis (Al).

14. A method of manufacturing a display assembly (1), said method comprising the steps of:

-providing a matrix (5) comprising a first material;

-writing a grating structure (6) through a section of said matrix (5) by means of femtosecond laser machining;

-applying said matrix (5) onto a flexible display structure (3) configured to be curved around a main axis (Al), such that said grating structure (6) is arranged adjacent said main axis (Al) of said flexible display structure (3).

15. The method according to claim 14, further comprising a last step of applying a coating layer (8) onto said matrix (5).