Foldable display device

Abstract

A foldable display device includes a support structure, a lower stress adjustment structure disposed on the support structure, an upper stress adjustment structure disposed on the lower stress adjustment structure, a covering layer disposed on the upper stress adjustment structure, and a function display structure disposed between the lower stress adjustment structure and the upper stress adjustment structure. The total thickness of the support structure, the lower stress adjustment structure, the upper stress adjustment structure, the covering layer and the function display structure is not greater than

Description

Technical Field

[0001] This invention relates to a foldable display device. Prior Technology

[0002] Recently, there has been an increasing demand for compact and portable display devices with large screen capabilities. Foldable display devices offer the convenience of compact size while providing a large screen. However, foldable display devices need to be repeatedly folded and unfolded, which can easily cause strain in the various layers of the device's structure. Excessive strain can lead to damage or failure of the foldable display device. Summary of the Invention

[0003] At least one embodiment of the present invention provides a foldable display device that reduces the strain of the foldable display device when folded by reducing the thickness and setting a stress adjustment structure, thereby improving reliability.

[0004] The foldable display device provided in at least one embodiment of the present invention includes a support structure, a lower stress adjustment structure, an upper stress adjustment structure, a cover layer, and a functional display structure. The lower stress adjustment structure is disposed on the support structure, the upper stress adjustment structure is disposed on the lower stress adjustment structure, the cover layer is disposed on the upper stress adjustment structure, and the functional display structure is disposed between the lower stress adjustment structure and the upper stress adjustment structure. The total thickness of the support structure, lower stress adjustment structure, upper stress adjustment structure, cover layer, and functional display structure is not greater than 750 micrometers. The functional display structure includes a component driving layer, an electronic ink layer, a transparent conductive resistive water layer, and a sealant. The electronic ink layer is disposed on the component driving layer, the transparent conductive resistive water layer is disposed on the electronic ink layer, and the sealant surrounds the electronic ink layer and connects the component driving layer and the transparent conductive resistive water layer. The thickness of the component driving layer, the thickness of the electronic ink layer, the thickness of the transparent conductive resistive water layer, and the thickness of the sealant are all not greater than 60 micrometers.

[0005] In at least one embodiment of the present invention, the material of the transparent conductive water layer comprises indium tin oxide and polymethyl methacrylate, polyimide or polyethylene terephthalate.

[0006] In at least one embodiment of the present invention, the Young's modulus of the sealant is not greater than 1 billion Pa.

[0007] In at least one embodiment of the present invention, the upper stress adjustment structure includes one or more upper adhesive layers, and the lower stress adjustment structure includes one or more lower adhesive layers, wherein the shear modulus of each upper adhesive layer is less than the shear modulus of each lower adhesive layer.

[0008] In at least one embodiment of the present invention, the thickness of each adhesive layer is not greater than 60 micrometers, and the shear modulus of each adhesive layer is not greater than 60 kPa.

[0009] In at least one embodiment of the present invention, each of the adhesive layers is an optical adhesive.

[0010] In at least one embodiment of the present invention, the functional display structure includes one or more functional layers, each functional layer having a thickness of no more than 160 micrometers, and the functional layers and the adhesive layer are alternately arranged.

[0011] In at least one embodiment of the present invention, two of the plurality of adhesive layers are respectively in contact with the transparent conductive water layer and the cover layer.

[0012] In at least one embodiment of the present invention, the stress adjustment structure comprises one or more lower film layers. The thickness of each lower film layer is no greater than 160 micrometers, and the lower adhesive layer and the lower film layer are staggered. The thickness of each lower adhesive layer is no greater than 60 micrometers, the shear modulus of each lower adhesive layer at a temperature between 20 and 40 degrees Celsius is greater than 100 kPa, and the shear modulus of each lower adhesive layer at a temperature not greater than 0 degrees Celsius is less than 2 MPa.

[0013] In at least one embodiment of the present invention, the lower adhesive layer is a pressure-sensitive adhesive.

[0014] In at least one embodiment of the present invention, the material of each of the lower film layers comprises polymethyl methacrylate, polyimide, or polyethylene terephthalate.

[0015] In at least one embodiment of the present invention, the support structure includes a support layer and an adhesive layer. The thickness of the support layer is no more than 300 micrometers, and the material of the support layer includes a metal or a polymer material. The adhesive layer is disposed on the support layer.

[0016] In at least one embodiment of the present invention, one of the plurality of lower adhesive layers contacts the element driving layer, and one of the plurality of lower film layers contacts the adhesive layer.

[0017] In at least one embodiment of the present invention, the thickness of the covering layer is not greater than 110 micrometers, and the material of the covering layer includes polymethyl methacrylate, polyimide or polyethylene terephthalate.

[0018] In at least one embodiment of the present invention, the foldable display device further includes a decorative pattern. The cover layer has an inner surface facing the upper stress adjustment structure, and the decorative pattern is disposed on the inner surface.

[0019] In at least one embodiment of the present invention, the electronic ink layer comprises a microcup electrophoretic display medium or a microcapsule electrophoretic display medium.

[0020] In at least one embodiment of the present invention, the microcup-type electrophoretic display medium or the microcapsule-type electrophoretic display medium comprises an electrophoretic solution and a plurality of colored particles distributed in the electrophoretic solution. Simple Explanation of the Diagram

[0021] Figure 1 is a top view of a foldable display device according to at least one embodiment of the present invention. Figure 2 is a schematic cross-sectional view along line a-a' in Figure 1. Figure 3 is a cross-sectional schematic diagram of a foldable display device according to at least another embodiment of the present invention. Figure 4 is a cross-sectional schematic diagram of a foldable display device according to at least another embodiment of the present invention. Implementation

[0022] The embodiments of the present invention will be discussed in detail below. However, it will be understood that the embodiments provide many applicable concepts that can be implemented in a wide variety of specific contexts. The discussed and disclosed embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0023] To clearly illustrate the technical features of this invention, the dimensions of the components in the drawings are enlarged proportionally, and the number of some components is reduced. Therefore, the description and explanation of the embodiments of this invention are not limited to the number of components in the drawings or the dimensions and shapes presented, but should cover dimensions, shapes, and deviations from these due to actual manufacturing processes and / or tolerances. For example, a flat surface shown in the drawings may have rough and / or non-linear characteristics, and an acute angle shown in the drawings may be a rounded corner. Therefore, the components presented in the drawings are primarily for illustration and are not intended to precisely depict the actual shape of the components, nor are they intended to limit the scope of protection claimed by this invention.

[0024] Secondly, the terms "approximately," "approximately," or "substantially" used in this invention not only cover explicitly stated numerical values ​​and ranges, but also the permissible deviation range understandable to those skilled in the art. This deviation range can be determined by errors generated during measurement, which may arise from limitations of the measurement system or process conditions. For example, two objects (e.g., planes or traces of a substrate) are "substantially parallel" or "substantially perpendicular." "Substantially parallel" and "substantially perpendicular" respectively indicate that the parallelism and perpendicularity between the two objects can include non-parallelism and non-perpendicularity caused by permissible deviation ranges.

[0025] Furthermore, "approximately" can indicate that the value is within one or more standard deviations, such as ±30%, ±20%, ±10%, or ±5%. The terms "approximately," "approximately," or "substantially" used in this invention can be selected based on the optical, etching, mechanical, or other properties to determine an acceptable range of deviations or standard deviations, and do not apply a single standard deviation to all of the aforementioned optical, etching, mechanical, and other properties.

[0026] The spatial relative terms used in this invention, such as "below," "under," "above," and "above," are for the convenience of describing the relative relationship between one element or feature and another, as illustrated in the figures. The true meaning of these spatial relative terms includes other orientations. For example, when the illustration is rotated 180 degrees vertically, the relationship between one element and another may change from "below" or "under" to "above" or "above." Furthermore, the spatial relative descriptions used in this invention should be interpreted in the same way.

[0027] Furthermore, the present invention can be implemented or applied through other different specific embodiments, and the various details of the present invention can also be combined, modified and changed in various embodiments based on different viewpoints and applications without departing from the concept of the present invention.

[0028] Figure 1 is a top view of a foldable display device 10 according to at least one embodiment of the present invention. Figure 2 is a cross-sectional view along line a-a' in Figure 1. Referring to Figures 1 and 2, the foldable display device 10 has a display area AA and a peripheral area PA adjacent to the display area AA, and the foldable display device 10 includes a support structure 100, a lower stress adjustment structure 200, an upper stress adjustment structure 400, a cover layer 500, and a functional display structure 300.

[0029] The lower stress adjustment structure 200 is disposed on the support structure 100, the upper stress adjustment structure 400 is disposed on the lower stress adjustment structure 200, the covering layer 500 is disposed on the upper stress adjustment structure 400, and the functional display structure 300 is disposed between the lower stress adjustment structure 200 and the upper stress adjustment structure 400. The total thickness of the support structure 100, the lower stress adjustment structure 200, the upper stress adjustment structure 400, the covering layer 500, and the functional display structure 300 is approximately no greater than 750 micrometers.

[0030] The functional display structure 300 includes a component driving layer 302, an electronic ink layer 304, a transparent conductive water layer 306, and an encapsulant 308. The electronic ink layer 304 is disposed on the component driving layer 302, the transparent conductive water layer 306 is disposed on the electronic ink layer 304, and the encapsulant 308 surrounds the electronic ink layer 304 and connects the component driving layer 302 and the transparent conductive water layer 306. The thicknesses of the component driving layer 302, the electronic ink layer 304, the transparent conductive water layer 306, and the encapsulant 308 are each approximately no greater than 60 micrometers.

[0031] By setting a transparent conductive water layer 306 with composite functions, the total thickness of the foldable display device 10 can be effectively reduced. Since the total thickness of each structure in the foldable display device 10 is not greater than approximately 750 micrometers and the thickness of each layer in the functional display structure 300 is not greater than approximately 60 micrometers, and by setting a lower stress adjustment structure 200 and an upper stress adjustment structure 400, the strain of the foldable display device 10 during folding can be reduced, thereby improving reliability.

[0032] In some embodiments, the transparent conductive water-resistant layer 306 may comprise a substrate of a transparent flexible polymer material, and a film layer formed by a transparent conductive material and a waterproof material is disposed on the surface of the aforementioned substrate, possessing light-transmitting, conductive, and water-blocking properties. The material of the transparent conductive water-resistant layer 306 may comprise indium tin oxide and polymethyl methacrylate, polyimide, polyethylene terephthalate, polyurethane, or polycarbonate. The Young's modulus of the sealant 308 is approximately no greater than 1 gigapascal (GPa), and the sealant 308 may be, for example, a polymer adhesive or tape, and the sealant 308 is disposed in the peripheral area PA of the foldable display device 10. Furthermore, the total thickness of the element driving layer 302, the electronic ink layer 304, and the transparent conductive water-resistant layer 306 may be approximately no greater than 90 micrometers.

[0033] In some embodiments, the element driving layer 302 may be a film layer formed of a metallic material and a flexible polymer material. The element driving layer 302 may include, for example, a switching element (not shown, such as a transistor) or other electronic components (not shown, such as a capacitor). The electronic ink layer 304 may include a microcup-type electrophoretic display medium or a microcapsule-type electrophoretic display medium, and the aforementioned electrophoretic display medium may include an electrophoretic solution and a plurality of colored particles distributed in the electrophoretic solution, but the present invention is not limited thereto. The thickness of the capping layer 500 is approximately no greater than 110 micrometers, and the material of the capping layer 500 includes polymethyl methacrylate, polyimide, polyethylene terephthalate, polyurethane, or polycarbonate.

[0034] Figure 3 is a cross-sectional schematic diagram of a foldable display device 11 according to at least another embodiment of the present invention. Referring to Figure 3, the embodiment in Figure 3 shares most of the same component structure, materials, and relative positional relationships with the embodiment in Figure 2. Furthermore, the top view of the foldable display device 11 in Figure 3 is substantially the same as the top view of the foldable display device 10 in Figure 2; therefore, the same technical features will not be described or illustrated here. The main difference between the two embodiments is that the foldable display device 11 further includes a decorative pattern 600, and the support structure 100 of the foldable display device 11 includes a support layer 102 and an adhesive layer 104; the lower stress adjustment structure 200 includes a lower adhesive layer 202 and a lower film layer 204; the functional display structure 300 includes a functional layer 310; and the upper stress adjustment structure 400 includes upper adhesive layers 402 and 402A.

[0035] As shown in Figure 3, the adhesive layer 104 is disposed on the support layer 102, the lower adhesive layer 202 contacts the element driving layer 302, the lower film layer 204 contacts the adhesive layer 104, the functional layer 310 is alternately disposed with the upper adhesive layers 402 and 402A, the upper adhesive layer 402 contacts the transparent conductive water layer 306, the upper adhesive layer 402A contacts the cover layer 500, and the cover layer 500 has an inner surface IS facing the upper stress adjustment structure 400, the decorative pattern 600 is disposed on the inner surface IS, and the decorative pattern 600 is disposed in the peripheral area PA of the foldable display device 11 and overlaps with the sealant 308.

[0036] In some embodiments, the shear modulus of the upper adhesive layers 402 and 402A is less than that of the lower adhesive layer 202. The thickness of the upper adhesive layers 402 and 402A is approximately no greater than 60 micrometers, and the shear modulus of the upper adhesive layers 402 and 402A is approximately no greater than 60 kPa. The upper adhesive layers 402 and 402A may be, for example, optical adhesives. The thickness of the lower adhesive layer 202 is approximately no greater than 60 micrometers, and the shear modulus of the lower adhesive layer 202 at a temperature of approximately 20 to 40 degrees Celsius is approximately greater than 100 kPa. The shear modulus of the lower adhesive layer 202 at a temperature of approximately no greater than 0 degrees Celsius is approximately less than 2 megapascals (MPa). The lower adhesive layer 202 may be, for example, pressure-sensitive adhesive. The thickness of the lower film layer 204 is approximately no more than 160 micrometers. The lower film layer 204 may be a film layer formed of a flexible polymer material, and the material of the lower film layer 204 may include polymethyl methacrylate, polyimide, polyethylene terephthalate, polyurethane, or polycarbonate.

[0037] By employing the stacked design of the lower adhesive layer 202, the lower film layer 204, the upper adhesive layers 402 and 402A, and the functional display structure 300, as well as the thickness and shear modulus design of the lower adhesive layer 202 and the upper adhesive layers 402 and 402A, the strain values ​​of the functional layer 310 and the component driving layer 302 are approximately 1.28% and 0.08%, respectively, achieving the effect of multiple neutral axes where the strain values ​​of the multiple layers are close to 0. In particular, the strain value of the component driving layer 302 is approximately 0.08%, which can prevent the circuit of the component driving layer 302 from breaking, and can pass the bending test at low temperature and high temperature. Therefore, it can effectively reduce the strain of the foldable display device 11 during folding, thereby improving reliability.

[0038] In some embodiments, the thickness of the functional layer 310 is approximately no greater than 160 micrometers. The functional layer 310 may be, for example, a touch functional layer or an optical functional layer with a transparent flexible polymer material as the substrate. The substrate material may include polymethyl methacrylate, polyimide, polyethylene terephthalate, polyurethane, or polycarbonate. The total thickness of the element driving layer 302, the electronic ink layer 304, the transparent conductive resistive water layer 306, and the functional layer 310 may be approximately no greater than 190 micrometers. The thickness of the support layer 102 is approximately no greater than 300 micrometers, and the material of the support layer 102 includes metal or polymer materials. The material of the adhesive layer 104 includes polymer adhesives or tapes. The material of the decorative pattern 600 includes ink.

[0039] Figure 4 is a cross-sectional schematic diagram of a foldable display device 12 according to at least another embodiment of the present invention. Referring to Figure 4, the embodiment in Figure 4 shares most of the same component structure, materials, and relative positional relationships with the embodiment in Figure 3. Furthermore, the top view of the foldable display device 12 in Figure 4 is substantially the same as the top view of the foldable display device 10 in Figure 2; therefore, the same technical features will not be described or illustrated here. The main difference between the embodiment in Figure 4 and the embodiment in Figure 3 is that the lower stress adjustment structure 200 of the foldable display device 12 further includes a lower adhesive layer 202A and a lower film layer 204A, the functional display structure 300 further includes a functional layer 310A, and the upper stress adjustment structure 400 further includes an upper adhesive layer 402B.

[0040] As shown in Figure 4, the lower adhesive layers 202 and 202A are alternately arranged with the lower film layers 204 and 204A. One of the lower adhesive layers 202 and 202A (such as lower adhesive layer 202A) contacts the element driving layer 302, and one of the lower film layers 204 and 204A (such as lower film layer 204) contacts the adhesive layer 104. The functional layers 310 and 310A are alternately arranged with the upper adhesive layers 402, 402A, and 402B. Two of the upper adhesive layers 402, 402A, and 402B (such as upper adhesive layers 402 and 402A) respectively contact the transparent conductive resistive water layer 306 and the cover layer 500.

[0041] In some embodiments, functional layer 310 may be one of a touch functional layer and an optical functional layer, while functional layer 310A may be the other of a touch functional layer and an optical functional layer, but the present invention is not limited thereto. The thickness, shear modulus and material of the upper adhesive layer 402B may be the same as those of the upper adhesive layers 402 and 402A, the thickness, shear modulus and material of the lower adhesive layer 202A may be the same as those of the lower adhesive layer 202, and the thickness and material of the lower film layer 204A may be the same as those of the lower film layer 204.

[0042] In summary, the present invention effectively reduces the total thickness of the foldable display device by setting a transparent conductive water layer with composite functions. Since the total thickness of each structure in the foldable display device is approximately no more than 750 micrometers and the thickness of each layer in the functional display structure is approximately no more than 60 micrometers, and by setting a lower stress adjustment structure and an upper stress adjustment structure, the strain of the foldable display device during folding is reduced, thereby improving reliability.

[0043] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Those skilled in the art can make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0044] 10, 11, 12: Foldable display devices 100: Supporting structure 102: Support layer 104: Adhesive layer 200: Stress Adjustment Structure 202, 202A: Lower adhesive layer 204, 204A: Lower film layer 300: Function Display Structure 302: Component Driver Layer 304: Electronic ink layer 306: Transparent conductive water layer 308: Sealant 310, 310A: Functional Layer 400: Upper stress adjustment structure 402, 402A, 402B: Top adhesive layer 500: Overlay 600: Decorative Pattern AA: Display area IS: Inner Surface PA: Surrounding Area

[0045] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A foldable display device, comprising: One supporting structure; A stress adjustment structure is installed on the supporting structure. An upper stress adjustment structure is disposed on the lower stress adjustment structure; a cover layer is disposed on the upper stress adjustment structure; and a functional display structure is disposed between the lower stress adjustment structure and the upper stress adjustment structure, wherein the total thickness of the support structure, the lower stress adjustment structure, the upper stress adjustment structure, the cover layer, and the functional display structure is not greater than 750 micrometers, and the functional display structure includes: a component driving layer; an electronic ink layer disposed on the component driving layer; a transparent conductive water layer disposed on the electronic ink layer; and an encapsulant surrounding the electronic ink layer and connecting the component driving layer and the transparent conductive water layer, wherein the thickness of the component driving layer, the thickness of the electronic ink layer, the thickness of the transparent conductive water layer, and the thickness of the encapsulant are each not greater than 60 micrometers.

2. The foldable display device as claimed in claim 1, wherein the material of the transparent conductive water-resistant layer includes indium tin oxide and polymethyl methacrylate, polyimide, polyethylene terephthalate, polyurethane, or polycarbonate.

3. The foldable display device as claimed in claim 1, wherein the Young's modulus of the sealant is not greater than 1 billion Pa.

4. The foldable display device as claimed in claim 1, wherein the upper stress adjustment structure includes one or more upper adhesive layers, the lower stress adjustment structure includes one or more lower adhesive layers, and the shear modulus of each upper adhesive layer is less than the shear modulus of each lower adhesive layer.

5. The foldable display device as claimed in claim 4, wherein the thickness of each adhesive layer is not greater than 60 micrometers and the shear modulus of each adhesive layer is not greater than 60 kPa.

6. The foldable display device as described in claim 5, wherein each of the adhesive layers is an optical adhesive.

7. The foldable display device as claimed in claim 5, wherein the functional display structure includes one or more functional layers, each functional layer having a thickness of no more than 160 micrometers, and the functional layers and the adhesive layers are alternately arranged.

8. The foldable display device as claimed in claim 5, wherein two of the adhesive layers are in contact with the transparent conductive water layer and the cover layer, respectively.

9. The foldable display device as claimed in claim 4, wherein the stress adjustment structure includes one or more lower film layers, each of the lower film layers having a thickness of no more than 160 micrometers, wherein the lower adhesive layers are staggered with the lower film layers, each of the lower adhesive layers having a thickness of no more than 60 micrometers, each of the lower adhesive layers having a shear modulus of more than 100 kPa at a temperature of 20 to 40 degrees Celsius, and each of the lower adhesive layers having a shear modulus of less than 2 MPa at a temperature of no more than 0 degrees Celsius.

10. The foldable display device as described in claim 9, wherein each of the lower adhesive layers is a pressure-sensitive adhesive.

11. The foldable display device as claimed in claim 9, wherein the material of each of the lower film layers includes polymethyl methacrylate, polyimide, polyethylene terephthalate, polyurethane, or polycarbonate.

12. The foldable display device as claimed in claim 9, wherein the support structure comprises: A support layer, the thickness of which is no more than 300 micrometers, the material of which includes metal or polymer material; And an adhesive layer is disposed on the support layer.

13. The foldable display device as claimed in claim 12, wherein one of the lower adhesive layers contacts the element driving layer and one of the lower film layers contacts the adhesive layer.

14. The foldable display device as claimed in claim 1, wherein the thickness of the cover layer is not greater than 110 micrometers, and the material of the cover layer includes polymethyl methacrylate, polyimide, polyethylene terephthalate, polyurethane, or polycarbonate.

15. The foldable display device as described in claim 1, further comprising: A decorative pattern, wherein the covering layer has an inner surface facing the stress adjustment structure, and the decorative pattern is disposed on the inner surface.

16. The foldable display device as claimed in claim 1, wherein the electronic ink layer comprises a microcup electrophoretic display medium or a microcapsule electrophoretic display medium.

17. The foldable display device as claimed in claim 16, wherein the microcup-type electrophoretic display medium or the microcapsule-type electrophoretic display medium comprises an electrophoretic solution and a plurality of colored particles distributed in the electrophoretic solution.

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