WO2021083526A1

WO2021083526A1 - Printed display stack for electronic device

Info

Publication number: WO2021083526A1
Application number: PCT/EP2019/079854
Authority: WO
Inventors: Sami MAATTANEN; Ilkka SAARINEN; Pasi PYLVAS
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2019-10-31
Filing date: 2019-10-31
Publication date: 2021-05-06
Also published as: CN114616531A

Abstract

A foldable display stack (1) for an electronic device comprising a cover structure (2) and a display structure (4). The cover structure (2) comprises a plurality of discrete layers (3), each discrete layer (3) having adhesive properties. The adhesive properties are sufficient to bond adjacent discrete layers (3) permanently together. The display structure (4) comprises at least one film layer, and a peripheral discrete layer (3) of the cover structure (2) bonds directly with a peripheral surface (4a) of the display structure (4). This facilitates a thinner and more flexible display stack.

Description

PRINTED DISPLAY STACK FOR ELECTRONIC DEVICE

TECHNICAL FIELD

The disclosure relates to a display stack for an electronic device comprising a cover structure and a display structure.

BACKGROUND

Foldable electronic devices, such as some smartphones, require a foldable display stack. Prior art display stacks comprise a relatively large number of layers, some of which are relatively stiff and which cannot stretch, such as e.g. metal sheets. The large number of layers makes it difficult to achieve a display stack which is foldable as well as free from permanent deformation and delamination.

Current display stacks are therefore relatively thick and stiff, making them unsuitable for use in foldable displays. Furthermore, the large number of layers makes the manufacturing process cumbersome.

SUMMARY

It is an object to provide an improved display stack. 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 foldable display stack for an electronic device comprising a cover structure comprising a plurality of discrete layers, each discrete layer having adhesive properties, the adhesive properties being sufficient to bond adjacent discrete layers permanently together, and a display structure comprising at least one film layer, a peripheral discrete layer of the cover structure bonding directly with a peripheral surface of the display structure.

Such a solution facilitates a foldable display stack which is significantly thinner and more flexible than prior art, which is necessary in order to achieve a genuinely foldable display stack. Furthermore, the present solution has better reliability than prior art solutions, substantially eliminating delamination of, and permanent deformation, to the display stack.

In a possible implementation form of the first aspect, the cover structure does not comprise adhesive layers, eliminating the need for all layers not operationally necessary for the display stack.

In a further possible implementation form of the first aspect, the cover structure comprises at least one of a cover layer, a polarizing layer, a touch sensor layer, and a grip layer, facilitating a cover structure which is a partially or fully pre-assembled component.

In a further possible implementation form of the first aspect, the cover structure comprises at least one conductive electrode and routing, the conductive electrode and routing being enclosed by two adjacent discrete layers.

In a further possible implementation form of the first aspect, the cover structure is optically transparent.

In a further possible implementation form of the first aspect, the cover layer is at least one of a scratch-resistant layer, a self-healing layer, and an anti-fingerprint layer. This provides protection to the surface of electronic device comprising the foldable display stack, and/or a positive tactile experience for the user. In a further possible implementation form of the first aspect, the cover layer comprises one of glass or polymer material.

In a further possible implementation form of the first aspect, the display structure comprises an OLED panel layer or an AMOLED panel layer, facilitating choosing a suitable display structure considering optical and mechanical restrictions.

In a further possible implementation form of the first aspect, the display stack is foldable, from an unfolded position wherein the discrete layers extend in parallel with each other and with a main plane of the display stack, in a first direction to a first folded position.

In a further possible implementation form of the first aspect, the foldable display stack is foldable from the unfolded position, in a second direction to a second folded position, the first direction and the second direction extending at angles >0 ° to the main plane, allowing a display stack which has a simultaneous in-fold design and out-fold design.

In a further possible implementation form of the first aspect, the display stack is elastically deformable in at least one direction parallel with the main plane, facilitating a significant reduction in the maximum stress and permanent deformation of the display stack.

According to a second aspect, there is provided a process for manufacturing a foldable display stack according to the above, wherein a first discrete layer is printed onto the peripheral surface, and wherein at least a second discrete layer is printed onto the first discrete layer, allowing a simplified assembly process generating less costs.

According to a third aspect, there is provided an electronic device comprising a foldable display stack according to the above, wherein a peripheral surface of the electronic device comprises a peripheral discrete layer of the cover structure, facilitating an electronic device having a display which is thinner and which has better reliability than prior art solutions. This and other aspects will be apparent from and the embodiments 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 illustration of a display stack in accordance with one embodiment of the present invention;

Fig. 2 shows a schematic illustration of a display stack in accordance with a further embodiment of the present invention.

DETAILED DESCRIPTION

The present disclosure relates to an electronic device, such as a smartphone, tablet, or wearable, comprising a foldable display stack 1. The foldable display stack 1 comprises a display structure 4 and a cover structure 2.

A peripheral surface of the electronic device comprises a peripheral discrete layer 3, 3a of the cover structure 2. The peripheral surface of the electronic device may, e.g., be a part of the front surface of the electronic device, the entire front surface of the electronic device, or the front surface and side or rear surfaces of the electronic device.

Different embodiments of the foldable display stack 1 are shown in Figs. 1 and 2.

The display structure 4 comprises at least one film layer, and a peripheral discrete layer 3 of the cover structure 2 bonds directly with a peripheral surface 4a of the display structure

4, as shown in Fig. 1. The display structure 4 may comprise an OLED panel layer or an

AMOLED panel layer, and the cover structure 2 may be optically transparent. The cover structure 2 comprises a plurality of discrete layers 3. Each discrete layer 3 has adhesive properties, the adhesive properties of all layers being substantially isotropic and sufficient to bond adjacent discrete layers 3 permanently together. All layers of the cover structure 2 extend in parallel with each other and with the film layer(s) of the display structure 4. Furthermore, all discrete layers, except for the peripheral layer comprising the peripheral surface of the electronic device, are arranged in direct abutment with two adjacent layers 3, 4, since there are no air gaps present within the foldable display stack 1.

Additionally, the cover structure 2 does not comprise any adhesive layers. The plurality of discrete layers 3 are printed on top of each other, eliminating any need for separate adhesive layers between the discrete layers 3. The discrete layers 3 are printed using finetuned stretchable and printable inks, adjacent ink layers 3 having mutually interacting adhesive properties.

The cover structure 2 comprises at least one of a cover layer 3a, preferably comprising a peripheral surface of the electronic device, a polarizing layer 3b, a touch sensor layer 3c, and a grip layer 3d.

The cover layer 3a may be at least one of a scratch-resistant layer, a self-healing layer, and an anti-finger print layer. Furthermore, the cover layer 3a may comprise one of glass or polymer material such as polyimide.

The polarizing layer 3b may comprise a linear polarizer or a circular polarizer, in particular suitable when the display structure 4 comprises an OFED panel layer or an AMOFED panel layer. The circular polarizer may, e.g., comprise of a linear polarizer and a quarter wave plate. Other solutions are however conceivable. The polarizing layer 3b may comprise only one material, preferably a liquid crystal polymer material. The polarizing layer 3b may comprise of two sub-layers coated onto each other. For example, for a circular polarizer comprising a linear polarizer sub-layer and a quarter wave sub-layer, the two sub- layers are coated as separate layers, the two sub-layers comprising of the same base material but having different polymer molecule orientation.

The touch sensor layer 3 c may comprise a touch sensor embedded within a discrete layer, or a discrete touch sensor layer in itself.

The grip layer 3d may be utilized to compensate for the material change between e.g. the touch sensor layer 3c and the peripheral surface 4a of the display structure 4.

The cover structure 2 may comprise at least one conductive electrode and routing 5, as shown in Fig. 2, the conductive electrode and routing 5 being enclosed by two adjacent discrete layers 3 or between a first discrete layer 3, 3d and a peripheral surface 4a of the display structure 4. The conductive electrode and routing 5 may be arranged in a single discrete layer 3 , or in several discrete layers 3. The cover structure 2 may further comprise at least one conductive shielding, arranged at a side opposite the cover layer 3a or interspersed between discrete layers 3 between the conductive electrode and routing 5 and the cover layer 3a. The conductive electrode and routing 5 may further comprise printed insulator bridges and a printed protective overlay (not shown).

The display stack 1 is foldable, from an unfolded position wherein the discrete layers 3 extend in parallel with each other, with the film layer(s) of the display structure 4, and with a main plane of the display stack 1 , in a first direction D 1 to a first folded position.

Furthermore, the foldable display stack 1 may be foldable from the unfolded position, in a second direction D2 to a second folded position, the first direction D1 and the second direction D2 extending at angles >0° to the main plane.

The foldable display stack 1 is elastically deformable in at least one direction parallel with the main plane, allowing the discrete layers and film layer(s) to stretch or compress as the foldable display stack 1 is folded. The present disclosure also relates to a process for manufacturing the foldable display stack 1, wherein the first discrete layer 3, 3d is printed onto the peripheral surface 4a of the display structure 4, and wherein at least a second discrete layer 3, 3c is printed onto the first discrete layer 3, 3d. Subsequently, as indicated in Fig.l, a third discrete layer 3, 3b is printed onto the second discrete layer 3, 3c, etc.

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.

Claims

1. A foldable display stack (1) for an electronic device comprising a cover structure (2) comprising a plurality of discrete layers (3), each discrete layer (3) having adhesive properties, said adhesive properties being sufficient to bond adjacent discrete layers (3) permanently together, a display structure (4) comprising at least one film layer, a peripheral discrete layer (3) of said cover structure (2) bonding directly with a peripheral surface (4a) of said display structure (4).

2. The foldable display stack (1 ) according to claim 1 , wherein said cover structure (2) does not comprise adhesive layers.

3. The foldable display stack (1) according to claim 1 or 2, wherein said cover structure (2) comprises at least one of a cover layer (3a), a polarizing layer (3b), a touch sensor layer (3c), and a grip layer (3d).

4. The foldable display stack (1) according to any one of the previous claims, wherein said cover structure (2) comprises at least one conductive electrode and routing (5), said conductive electrode and routing (5) being enclosed by two adjacent discrete layers (3).

5. The foldable display stack (1) according to any one of the previous claims, wherein said cover structure (2) is optically transparent.

6. The foldable display stack (1) according to any one of claims 3 to 5, wherein said cover layer (3a) is at least one of a scratch-resistant layer, a self-healing layer, and an anti-finger print layer.

7. The foldable display stack (1) according to any one of claims 3 to 6, wherein said cover layer (3 a) comprises one of glass or polymer material.

8. The foldable display stack (1) according to any one of the previous claims, wherein said display structure (4) comprises an OLED panel layer or an AMOLED panel layer.

9. The foldable display stack (1) according to any one of the previous claims, wherein said display stack (1) is foldable, from an unfolded position wherein said discrete layers (3) extend in parallel with each other and with a main plane of said display stack (1), in a first direction (D 1 ) to a first folded position.

10. The foldable display stack (1) according claim 9, wherein said foldable display stack (1) is foldable from said unfolded position, in a second direction (D2) to a second folded position, said first direction (Dl) and said second direction (D2) extending at angles >0° to said main plane.

11. The foldable display stack (1) according to claim 9 or 10, wherein said display stack (1) is elastically deformable in at least one direction parallel with said main plane.

12. A process for manufacturing a foldable display stack (1) according to any one of claims 1 to 11, wherein a first discrete layer (3, 3d) is printed onto the peripheral surface (4a( of the display structure (4), and wherein at least a second discrete layer (3, 3c) is printed onto said first discrete layer (3, 3d).

13. An electronic device comprising a foldable display stack (1) according to any one of claims 1 to 11 , wherein a peripheral surface of said electronic device comprises a peripheral discrete layer (3, 3a) of said cover structure (2).