KR102545647B1 - Foldable display device - Google Patents

Abstract

The present invention relates to a foldable display device, which includes a display panel, a first protection member on the display panel, and a second protection member on the first protection member, wherein the modulus of the first protection member is Since is smaller than the modulus of the second protection member, the foldable display device can be effectively protected from impact applied to the surface, and damage to the protection member due to folding can be prevented.

Description

Foldable display device {FOLDABLE DISPLAY DEVICE}

The present invention relates to a foldable display device, and more particularly, to a foldable display device capable of minimizing damage caused by an external impact and having enhanced folding characteristics.

Recently, as we enter the full-fledged information age, the display field that visually expresses electrical information signals has developed rapidly. In response to this, various foldable display devices (Display Device) has been developed and is rapidly replacing the existing cathode ray tube (CRT).

Specific examples of such a display device include a liquid crystal display (LCD), an organic light emitting display (OLED), an electrophoretic display (EPD), a plasma display (PDP), and an electrowetting display (EWD). .

Among these various display devices, a foldable display device includes a substrate made of a material having flexibility and can be folded. At this time, when the rigidity of the surface protection member of the foldable display device is increased, the surface of the foldable display device can be effectively protected, but the degree of damage to the protection member increases as the foldable display device is folded.

The inventors of the present invention have recognized that it is difficult for a protective member for protecting the surface of a foldable display device to satisfy both impact resistance and folding characteristics. Specifically, when the impact resistance of the protection member is increased, the protection member becomes stronger against impact applied to the surface, but may be easily damaged, such as cracking, as the foldable display device is folded. Conversely, when the folding characteristic of the protection member is increased, the degree of damage to the protection member is reduced and the radius of curvature of the protection member is reduced as the foldable display device is folded, but the protection member due to an impact applied to the surface of the protection member The degree of damage can be increased.

Accordingly, the inventors of the present invention sequentially laminate two protective members having different characteristics on top of the display panel, and make the modulus of the upper protective member higher than the modulus of the lower protective member, so that the two A foldable display device having a new structure for simultaneously improving the folding characteristics and impact resistance of the entire protective member has been invented.

An object of the present invention is to provide a foldable display device capable of improving both impact resistance and folding characteristics by sequentially stacking two protective members having different characteristics on top of a display panel.

In addition, another problem to be solved by the present invention is a foldable display in which impact resistance of the upper protection member and the lower protection member can be improved by disposing a chemical reinforcement layer on the upper protection member and disposing a hard coating layer on the lower protection member. to provide the device.

Another problem to be solved by the present invention is to provide a foldable display device in which an upper protection member and a lower protection member can be separated from each other or reattached to each other by disposing a reworkable adhesive layer between two protection members. is to provide

In addition, another problem to be solved by the present invention is to dispose a light blocking layer between two protective members or between the protective member and the display panel to effectively block light outside the display panel and at the same time reduce the thickness of the adhesive layer. Accordingly, an object of the present invention is to provide a foldable display device capable of effectively reducing the thickness of the foldable display device.

In addition, another problem to be solved by the present invention is to dispose a phase retardation layer delaying a phase by λ/4 between two protective members so that light linearly polarized by a polarization layer included in a display panel passes through the retardation layer. An object of the present invention is to provide a foldable display device capable of preventing an image on the screen of the foldable display device from being invisible when polarized glasses or the like are used by circularly polarizing light passing therethrough.

The tasks of the present invention are not limited to the tasks mentioned above, and other tasks not mentioned will be clearly understood by those skilled in the art from the following description.

In order to solve the above problems, a foldable display device according to an exemplary embodiment of the present invention includes a display panel, a first protection member on the display panel, and a second protection member on the first protection member. The modulus of the member may be smaller than the modulus of the second protection member. Accordingly, it is possible to effectively protect the foldable display device from impact applied to the surface and prevent damage to the protective member due to folding.

A foldable display device according to another embodiment of the present invention includes a display panel and a first protection member and a second protection member disposed on the display panel, wherein the first protection member is more prone to folding than the second protection member. It is a protection member for improving characteristics, and the second protection member may be a protection member for improving impact resistance compared to the first protection member. Accordingly, both the folding characteristics and impact resistance of the protective member protecting the surface of the foldable display device may be improved.

Other embodiment specifics are included in the detailed description and drawings.

The present invention has an effect of effectively protecting the foldable display device from an impact applied to the surface of the foldable display device and preventing damage to the protective member as the foldable display device is folded.

According to the present invention, the two protective members can be separated from each other and re-attached, and thus, the protective member disposed above can be replaced with a new protective member.

The present invention has an effect of effectively blocking light emitted from the inside of the display device outside the foldable display device and at the same time reducing the thickness of the foldable display device.

The present invention has an effect of reducing the thickness of the foldable display device while allowing a color filter or color pattern layer to be seen on the outside of the foldable display device.

The present invention has an effect of preventing a phenomenon in which an image of a foldable display device is viewed as black even when viewed through polarized glasses.

Effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the present specification.

1 is an exploded perspective view of a foldable display device according to an exemplary embodiment of the present invention.
2 is a cross-sectional view of a foldable display device according to an exemplary embodiment.
3 is a cross-sectional view of a foldable display device according to an exemplary embodiment of the present invention when it is folded.
4 is a cross-sectional view of a foldable display device according to another exemplary embodiment of the present invention.
5 is a cross-sectional view of a foldable display device according to another exemplary embodiment of the present invention.
6 is a cross-sectional view of a foldable display device according to another exemplary embodiment of the present invention.
7 is a cross-sectional view of a foldable display device according to another exemplary embodiment of the present invention.
8 is a cross-sectional view of a foldable display device according to another exemplary embodiment of the present invention.

Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the detailed description of the following embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, only these embodiments make the disclosure of the present invention complete, and common knowledge in the art to which the present invention belongs. It is provided to fully inform the holder of the scope of the invention, and the present invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present invention are illustrative, so the present invention is not limited to the details shown. Like reference numbers designate like elements throughout the specification. In addition, in describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. When 'includes', 'has', 'consists of', etc. mentioned in this specification is used, other parts may be added unless 'only' is used. In the case where a component is expressed in the singular, the case including the plural is included unless otherwise explicitly stated.

In interpreting the components, even if there is no separate explicit description, it is interpreted as including the error range.

In the case of a description of a positional relationship, for example, 'on top of', 'on top of', 'at the bottom of', 'next to', etc. Or, unless 'directly' is used, one or more other parts may be located between the two parts.

When an element or layer is referred to as “on” another element or layer, it includes all cases where another element or layer is directly on top of another element or another layer or other element intervenes therebetween.

Although first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are only used to distinguish one component from another. Therefore, the first component mentioned below may also be the second component within the technical spirit of the present invention.

Like reference numbers designate like elements throughout the specification.

The size and thickness of each component shown in the drawings are shown for convenience of description, and the present invention is not necessarily limited to the size and thickness of the illustrated components.

Each feature of the various embodiments of the present invention can be partially or entirely combined or combined with each other, and as those skilled in the art can fully understand, various interlocking and driving operations are possible, and each embodiment can be implemented independently of each other. It may be possible to implement together in an association relationship.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is an exploded perspective view of a foldable display device according to an exemplary embodiment of the present invention. 2 is a cross-sectional view of a foldable display device according to an exemplary embodiment. 3 is a cross-sectional view of a foldable display device according to an exemplary embodiment of the present invention when it is folded. FIG. 2 is a cross-sectional view of the foldable display device 100 of FIG. 1 when it is not folded, and FIG. 3 is a cross-sectional view of the foldable display device 100 of FIG. 1 when it is folded. Referring to FIGS. 1 to 3 , the foldable display 100 includes a display panel 110 , a first protection member 120 and a second protection member 130 .

1 to 3 , the display panel 110 includes a display element used to display an image, various driving elements and wires for driving the display element.

The display panel 110 may include a substrate. The substrate is a substrate for protecting various components of the foldable display device 100 . The substrate may be made of an insulating material having flexibility. For example, the substrate may be made of plastic such as polyimide, but is not limited thereto.

The display panel 110 includes a display area AA and a non-display area NA surrounding the display area AA. In the present specification, a case where the non-display area NA surrounds the display area AA is described as an example, but is not limited thereto, and the non-display area NA may be present only in a portion outside the display area AA.

The display area AA is an area where an image is displayed in the foldable display 100, and a display element and various driving elements for driving the display element are disposed in the display area AA. For example, a plurality of pixels may be disposed in the display area AA. Also, for example, the display element may include an organic light emitting element, and the driving element may include a transistor, a capacitor, and wiring.

The non-display area NA is an area surrounding the display area AA. The non-display area NA is an area in which the image of the foldable display 100 is not displayed, and wiring or circuitry is formed. An external module, for example, a chip on film (COF) may be disposed in the non-display area NA. The COF may be electrically connected to the substrate through the pad. The COF may include a base film made of an insulating material and a driving IC formed on the base film. The COF may supply power voltages and data voltages to the display area AA through pads.

1 to 3 , a first protection member 120 and a second protection member 130 are sequentially stacked and disposed on the display panel 110 . In detail, the first protection member 120 and the second protection member 130 are members to protect the foldable display device 100 from an impact applied to the surface of the foldable display device 100 .

Specifically, the modulus of the first protection member 120 may be smaller than the modulus of the second protection member 130 . Modulus is an elastic modulus representing a rate of deformation with respect to stress applied to the protection member, and when the modulus is relatively high, the hardness may be relatively high. Therefore, the first protection member 120 may be a member having ductility compared to the second protection member 130 .

Thus, the first protection member 120 may be a member for improving folding characteristics more than the second protection member 130 . The folding property means a property of enduring stress applied by folding. When the folding characteristics are improved, it can better withstand the stress applied by folding. As described above, the modulus of the first protection member 120 may be smaller than the modulus of the second protection member 130, and thus, the first protection member 120 may be softer than the second protection member 130. there is. Accordingly, the first protection member 120 can better withstand the stress applied by folding than the second protection member 130 . That is, the minimum radius of curvature when the first protection member 120 is maximally folded without being damaged, such as cracks, may be smaller than the minimum radius of curvature of the second protection member 130 . Accordingly, the folding characteristics of the first protection member 120 may be superior to those of the second protection member 130, and even when the foldable display 100 is folded, the first protection member 120 is easily damaged. The surface of the foldable display device 100 can be protected without being damaged.

Also, the first protection member 120 may be a plastic film. Specifically, the first protection member 120 may be made of a plastic material having flexibility, for example, it may be made of polyimide, polyacrylate, polyacetate, or the like. . However, it is not limited thereto.

Referring to FIGS. 1 to 3 , the second protection member 130 is disposed on the first protection member 120 . The second protection member 130 is a member for protecting the foldable display device 100 from an impact applied to the surface of the foldable display device 100 .

Specifically, the second protection member 130 may be a protection member for improving impact resistance compared to the first protection member 120 . When the impact resistance is improved, damage such as cracks does not occur due to external impact applied to the surface and can better withstand. As described above, the second protection member 130 may have a higher modulus than the first protection member 120 and may be more rigid than the first protection member 120 . Accordingly, the second protection member 130 can withstand external impact applied to the surface better than the first protection member 120 . That is, the maximum magnitude of external impact that the second protection member 130 can withstand without being damaged, such as cracking, may be greater than the maximum magnitude of external impact of the first protection member 120 . Accordingly, the impact resistance of the second protection member 130 may be superior to that of the first protection member 120 , and the second protection member 130 may be affected by an external shock applied to the surface of the foldable display 100 . is not easily damaged and can effectively protect the surface of the foldable display device 100 .

Also, the second protection member 130 may be a glass substrate made of glass. However, it is not limited thereto, and the second protection member 130 may be made of a silicon-based or polyurethane-based material.

When the second protection member 130 is a glass substrate, the second protection member 130 may have a thickness of 80 μm or more. When the thickness of the second protective member 130 is smaller than 80 μm, the impact resistance of the second protective member 130 may not protect the foldable display 100 from impact applied to the surface of the foldable display 100. can be reduced to an extent. Accordingly, the second protective member 130 may not be damaged by an external force applied to the surface of the foldable display 100 by being formed to have a thickness of 80 μm or more.

When the second protection member 130 is made of a silicon-based material or a polyurethane-based material, the thickness of the second protection member 130 may be 200 μm or more. When the thickness of the second protection member 130 is smaller than 200 μm, the impact resistance of the second protection member 130 may not protect the foldable display 100 from an impact applied to the surface of the foldable display 100. can be reduced to an extent. Accordingly, the second protection member 130 may not be damaged by an external force applied to the surface of the foldable display device 100 by being formed to have a thickness of 200 μm or more.

Also, in some embodiments, the second protection member 130 may be made of a shape memory polymer. The shape memory polymer refers to a polymer that can memorize an initial polymer form and return to the initial polymer form from a deformed form by stimulation such as temperature or pressure. The second protective member 130 made of a shape memory polymer may return to its initial polymer form by stimulation of heat, electricity, or a magnetic field, but is not limited thereto. In addition, when the external pressure is removed, the second protection member 130 made of a shape memory polymer is immediately restored with a degree of restoration of 70% or more, and then returns to its initial polymer form with a degree of restoration of 95% or more. there is. However, the degree of restoration of the second protection member 130 is not limited thereto.

Also, when the second protection member 130 is made of a shape memory polymer, the second protection member 130 may have a thickness of 200 μm or more. When the thickness of the second protection member 130 is less than 200 μm, the impact resistance of the second protection member 130 does not effectively protect the foldable display 100 from an external shock applied to the surface of the second protection member 130. Otherwise, damage such as cracks may occur in the second protection member 130 . Accordingly, when the second protection member 130 is made of a shape memory polymer, the thickness of the second protection member 130 is 200 μm or more, so that the surface of the foldable display 100 can be effectively protected from external impact. In addition, the second protective member 130 made of the shape memory polymer may include a coating layer capable of protecting the shape memory polymer layer from moisture or the like on at least one of the upper and lower surfaces of the shape memory polymer. However, it is not limited thereto.

Referring to FIG. 3 , the foldable display 100 may be configured to be out-folded. Out-folding means that the foldable display device 100 is folded so that the second protection member 130 is positioned on the outside and the display panel 110 is positioned on the inside. As shown in FIG. 3 , the foldable display device 100 may be out-folded so that the first protection member 120 and the second protection member 130 are positioned on the outside and the display panel 110 is positioned on the inside. Also, the first protection member 120 and the second protection member 130 may protect the outer surface of the out-folded foldable display device 100 from external impact.

In the case of a conventional foldable display device, both impact resistance and folding characteristics of the protection member protecting the surface of the foldable display device may not be satisfied. Specifically, when the modulus of the protection member is increased and thus the rigidity is increased, the impact resistance is increased, so that the surface of the foldable display device can be effectively protected. However, in this case, the minimum curvature radius at which damage such as cracks of the protection member does not occur may be increased, and thus, the protection member may be easily damaged according to folding of the foldable display device. Conversely, when the modulus of the protective member is reduced and the ductility is increased, the minimum radius of curvature at which damage such as cracks does not easily occur may be reduced even when the foldable display device is folded due to increased folding characteristics. there was. However, in this case, since the impact resistance of the protective member is reduced, damage such as cracks may easily occur in the protective member due to an impact applied to the surface of the foldable display device, thereby effectively protecting the foldable display device from external shocks. could not protect As such, in the case of the protective member of the foldable display device, it is difficult to satisfy both impact resistance and folding characteristics.

Unlike this, in the case of the foldable display device 100 according to an exemplary embodiment of the present invention, two protection members 120 and 130 having different moduli are sequentially disposed on the display panel 110 . The modulus of the first protection member 120 disposed on the display panel 110 may be smaller than the modulus of the second protection member 130 disposed on the first protection member 120 . That is, the first protection member 120 is disposed on the display panel 110 to improve folding characteristics by being relatively soft, and the second protection member 120 to be relatively rigid to improve impact resistance is disposed on the first protection member 120 . A member 130 is disposed. Accordingly, the foldable display 100 is protected from external impact applied to the surface of the foldable display 100 by the first protection member 120 and the second protection member 130 disposed on the display panel 110 . damage to the first protection member 120 and the second protection member 130 when the foldable display 100 is folded is minimized by effectively protecting the can

In addition, in the case of the foldable display device 100 according to an exemplary embodiment of the present invention, the second protection member 130 having a relatively high modulus is located outside the foldable display device 100 more than the first protection member 120. The surface of the foldable display device 100 can be more effectively protected. When the foldable display 100 is configured to be out-folded as shown in FIG. 3 , the second protection member 130 in the folded area may be more exposed to external impact. In this case, the second protection member 130 has a higher modulus than the first protection member 120 and is a member for improving impact resistance. Accordingly, even when the foldable display 100 is out-folded, the second protection member 130 is disposed on the first protection member 120 and is disposed on the outer surface of the foldable display 100 . 2 The second protection member 130 may not be easily damaged even by an external impact applied to the surface of the protection member 130 . Thus, the outer surface of the foldable display device 100 can be effectively protected.

4 is a cross-sectional view of a foldable display device according to another exemplary embodiment of the present invention. The foldable display device 400 of FIG. 4 is substantially different from the foldable display device 100 of FIGS. 1 to 3 except that the first protection member 420 and the second protection member 430 are different. Since it is the same, redundant description is omitted.

Referring to FIG. 4 , a first protection member 420 is disposed on the display panel 110 . The first protective member 420 includes a first base member 421 , a first reinforced coating layer 422 and a second reinforced coating layer 423 . Since the first base member 421 is substantially the same as the first protection member 120 of FIGS. 1 to 3 , duplicate descriptions will be omitted.

A first reinforced coating layer 422 is disposed on the lower surface of the first base member 421 . The first reinforcement coating layer 422 is a layer that enhances surface hardness of the first protection member 420 . The first reinforced coating layer 422 may be formed, for example, by applying a reinforced coating composition solution to the lower surface of the first base member 421 and curing it, but is not limited thereto. The first reinforced coating layer 422 may be made of at least one of acrylic, polyurethane, polyester, polyether, olefin, polyimide, silicone, and epoxy, but is not limited thereto. In addition, the thickness of the first reinforced coating layer 422 may be 5 μm to 20 μm, but is not limited thereto.

A second reinforced coating layer 423 is disposed on the upper surface of the first base member 421 . The second reinforcement coating layer 423 is a layer that enhances surface hardness of the first protection member 420 . The second reinforced coating layer 423 may also be formed through the same process as the first reinforced coating layer 422, but is not limited thereto. The second reinforced coating layer 423 may be made of the same material as the first reinforced coating layer 422, and for example, at least one of acrylic, polyurethane, polyester, polyether, olefin, polyimide, silicone, and epoxy. It may be made of a series of materials, but is not limited thereto. In addition, the thickness of the second reinforced coating layer 423 may be 5 μm to 20 μm, but is not limited thereto.

Meanwhile, unlike that shown in FIG. 4 , one of the first reinforced coating layer 422 and the second reinforced coating layer 423 may be omitted, and thus, the first protective member 420 is provided with the first base member 421 and It may include only the first reinforced coating layer 422 or only the first base member 421 and the second reinforced coating layer 423 .

Referring to FIG. 4 , the second protection member 430 disposed on the first protection member 420 includes a second base member 431, a first chemical enhancement layer 432 and a second chemical enhancement layer 433. includes Since the second base member 431 is substantially the same as the second protection member 130 of FIGS. 1 to 3 , overlapping descriptions will be omitted.

A first chemical enhancement layer 432 is disposed on the lower surface of the second base member 431 . The first chemically strengthened layer 432 means a layer obtained by chemically strengthening the second base member 431 . That is, the second base member 431 may be formed up to an area where the first chemically enhanced layer 432 is disposed, and the second base member 431 is chemically strengthened to form the first chemically enhanced layer 432. can Chemical strengthening is a process of strengthening a specific layer through chemical treatment. For example, a process of substituting a specific alkali metal ion with another alkali metal ion may be used, but is not limited thereto.

Also, the thickness d2 of the first chemical reinforcement layer 432 may be 8 μm to 15 μm. When the thickness d2 of the first chemical reinforcement layer 432 is less than 8 μm, the surface of the second base member 431 may not be effectively strengthened. Also, when the thickness d2 of the first chemical enhancement layer 432 is greater than 15 μm, the flexibility of the first chemical enhancement layer 432 may be reduced, and thus the folding characteristics of the foldable display 400 may be reduced. Accordingly, the first chemical reinforcement layer 432 is formed to have a thickness d2 of 8 μm to 15 μm, thereby effectively strengthening the surface of the second base member 431, and the foldable display 400 can be easily folded. there is.

Also, a second chemical enhancement layer 433 is disposed on the upper surface of the second base member 431 . The second chemical strengthening layer 433 refers to a layer obtained by chemically strengthening the second base member 431 . That is, the second base member 431 may be formed up to an area where the second chemical enhancement layer 433 is disposed, and the second base member 431 is chemically strengthened to form the second chemical enhancement layer 433. can Also, the thickness d3 of the second chemical reinforcement layer 433 may be 8 μm to 15 μm. When the thickness d3 of the second chemical reinforcement layer 433 is less than 8 μm, the surface of the second base member 431 may not be effectively strengthened. In addition, when the thickness d3 of the second chemical enhancement layer 433 is greater than 15 μm, the flexibility of the second chemical enhancement layer 433 may be reduced and thus the folding characteristics of the foldable display device 400 may be reduced. Accordingly, the second chemical reinforcement layer 433 is formed to have a thickness d3 of 8 μm to 15 μm, thereby effectively strengthening the surface of the second base member 431, and the foldable display 400 can be easily folded. there is. The thickness d3 of the second chemical enhancement layer 433 may be the same as the thickness d2 of the first chemical enhancement layer 432, but is not limited thereto.

Referring to FIG. 4 , the thickness d1 of the second base member 431 is 80 μm or less, and the thickness d2 of the first chemical reinforcement layer 432 and the thickness d3 of the second chemical reinforcement layer 433 Each may be 10 μm or less. Specifically, the thickness (d1) of the second base member 431 is greater than 80 μm, and the thickness (d2) of the first chemical reinforcement layer 432 and the thickness (d3) of the second chemical reinforcement layer 433 are each 10 μm. If it is greater than the radius of curvature, the minimum radius of curvature that the second protection member 430 can withstand without being damaged, such as being cracked, may increase to such an extent that the foldable display 400 cannot be sufficiently folded. Accordingly, the thickness d1 of the second base member 431 is 80 μm or less, and the thickness d2 of the first chemical reinforcement layer 432 and the thickness d3 of the second chemical reinforcement layer 433 are each 10 μm or less. As a result, even when the foldable display 400 is sufficiently folded, damage such as cracks may not occur in the second protection member 430 .

Referring to FIG. 4 , when the thickness d1 of the second base member 431 is 80 μm or less, the difference between the thickness d1 of the second base member 431 and the thickness d2 of the first chemical strengthening layer 432 The ratio (d1/d2) and the ratio (d1/d3) of the thickness (d1) of the second base member 431 and the thickness (d3) of the second chemically enhanced layer 433 may be 5.3 to 6.5.

Specifically, the ratio (d1) of the thickness (d1) of the second base member 431 and the thickness (d2) of the first chemically enhanced layer 432 while the thickness (d1) of the second base member 431 is 80 μm or less. /d2) and the ratio (d1/d3) of the thickness d1 of the second base member 431 and the thickness d3 of the second chemical enhancement layer 433 is greater than 6.5, the first chemical enhancement layer 432 The thickness d2 of ) or the thickness d3 of the second chemical reinforcement layer 433 may be too thin to effectively reinforce the upper and lower surfaces of the second base member 431 . Therefore, when the thickness (d1) of the second base member 431 is 80 μm or less, the ratio (d1/ d2) and the ratio (d1/d3) of the thickness d1 of the second base member 431 and the thickness d3 of the second chemical enhancement layer 433 is 6.5 or less, so that the first chemical enhancement layer 432 And the second chemical reinforcement layer 433 can effectively strengthen the upper and lower surfaces of the second protection member 430 .

In addition, the ratio of the thickness d1 of the second base member 431 and the thickness d2 of the first chemically strengthened layer 432 (d1/ d2) and the ratio (d1/d3) of the thickness d1 of the second base member 431 and the thickness d3 of the second chemical strengthening layer 433 is less than 5.3, the second base member 431 The thickness d1 may be so thin that the second protection member 430 may not effectively protect the foldable display 400 from external shocks to the foldable display 400 . Therefore, when the thickness (d1) of the second base member 431 is 80 μm or less, the ratio (d1/ d2) and the ratio (d1/d3) of the thickness (d1) of the second base member 431 and the thickness (d3) of the second chemical reinforcement layer 433 is 5.3 or more, so that the second protection member 430 is protected from the outside. The foldable display 400 may be effectively protected from impact.

Meanwhile, unlike that shown in FIG. 4 , one of the first chemical enhancement layer 432 and the second chemical enhancement layer 433 may be omitted, and thus, the second protective member 430 is the second base member 431 ) and the first chemical enhancement layer 432 or only the second base member 431 and the second chemical enhancement layer 433 may be included.

In the case of the foldable display device 400 according to another embodiment of the present invention, the first protective member 420 includes a first reinforced coating layer 422 and a second reinforced coating layer 423, and the second protective member ( 430) includes a first chemical enhancement layer 432 and a second chemical enhancement layer 433. Thus, the rigidity of the upper and lower surfaces of the first protection member 420 may be increased, and the rigidity of the upper and lower surfaces of the second protection member 430 may be increased. Therefore, even if an external impact is applied to the first protection member 420 and the second protection member 430, they may not be easily damaged. Also, even when the foldable display 400 is folded, the ability of the first protection member 420 and the second protection member 430 to withstand applied stress can be increased, and thus the first protection member 420 and Damage such as cracking to the second protection member 430 may not easily occur.

5 is a cross-sectional view of a foldable display device according to another exemplary embodiment of the present invention. The foldable display device 500 of FIG. 5 is substantially the same as the foldable display device 400 of FIG. 4 except that the adhesive layer 540 is different, and thus duplicate descriptions are omitted.

Referring to FIG. 5 , an adhesive layer 540 is disposed between the first protection member 420 and the second protection member 430 . The adhesive layer 540 is a component for bonding the first protection member 420 and the second protection member 430 together.

Specifically, the adhesive layer 540 may have reworkability. The fact that the adhesive layer 540 has re-adhesiveness means that the two layers adhered by the adhesive layer 540 can be easily separated from each other or reattached again. That is, the adhesive layer 540 may adhere the first protection member 420 and the second protection member 430 to each other, but the first protection member 420 and the second protection member 430 are easily separated by an external force. may be separated.

The adhesive strength of the adhesive layer 540 may be 100 gf/inch or less. When the adhesive strength of the adhesive layer 540 is greater than 100 gf/inch, the amount of external force for separating the first protection member 420 and the second protection member 430 may increase. In this case, the first protection member 420 and the second protection member 430 may not be easily separated by human power, and even if they can be separated, the first protection member 420 or the second protection member 430 ) may be damaged, such as being cracked. Therefore, the adhesive layer 540 of the foldable display device 500 according to another exemplary embodiment of the present invention has an adhesive strength of 100 gf/inch or less, so that the first protection member 420 and the second protection member 430 are not suitable for humans. They can be easily separated from each other without damage by an appropriately sized external force, such as the force of

Also, the adhesive layer 540 may be made of at least one material of silicone and acrylic, but is not limited thereto.

Also, the adhesive layer 540 may have a thickness of 10 μm to 100 μm. When the thickness of the adhesive layer 540 is less than 10 μm, the adhesive strength of the adhesive layer 540 may be reduced to a hardness that prevents adhesion between the first protection member 420 and the second protection member 430 . And, when the thickness of the adhesive layer 540 is greater than 100 μm, the adhesive strength of the adhesive layer 540 can be increased to such an extent that the first protection member 420 and the second protection member 430 cannot be easily separated by human power. And, even if the first protection member 420 and the second protection member 430 can be separated, the first protection member 420 or the second protection member 430 may be damaged such as being cracked. Accordingly, the adhesive layer 540 of the foldable display device 500 according to another embodiment of the present invention has a thickness of 10 μm to 100 μm, thereby effectively bonding the first protection member 420 and the second protection member 430 together. And, the first protection member 420 and the second protection member 430 can be easily separated from each other without damage by an appropriately sized external force such as human power.

Also, the modulus of the adhesive layer 540 may be 10 ⁴ Mpa or less. When the modulus of the adhesive layer 540 is greater than 10 ⁴ Mpa, the minimum radius of curvature when the adhesive layer 540 is folded may increase, and thus, when the foldable display device 500 is folded, the adhesive layer 540 has Damage such as cracks may occur. Therefore, since the modulus of the adhesive layer 540 of the foldable display 500 according to another embodiment of the present invention is 10 ⁴ Mpa or less, damage such as cracks occurs even when the foldable display 500 is folded. It may not be.

In the case of the foldable display 500 according to another exemplary embodiment of the present invention, an adhesive layer 540 having readhesiveness is disposed between the first protection member 420 and the second protection member 430 . Accordingly, the first protection member 420 and the second protection member 430 may be adhered to each other, and the first protection member 420 and the second protection member 430 may be separated from each other by an external force such as human power. It can be. Accordingly, the display panel 110 and the first protection member 420 may be separated from the second protection member 430 . Accordingly, the second protection member 430 may be replaced with a new second protection member 430 and attached again.

6 is a cross-sectional view of a foldable display device according to another exemplary embodiment of the present invention. Compared to the foldable display 500 of FIG. 5 , the foldable display 600 of FIG. 6 includes a first adhesive layer 641 , a second adhesive layer 642 , a first light blocking layer 651 , and a second light blocking layer. Except that 652 is different, it is substantially the same, and duplicate description is omitted.

Referring to FIG. 6 , a first adhesive layer 641 is disposed between the display panel 110 and the first protection member 420 . The first adhesive layer 641 is a component that bonds the display panel 110 and the first protection member 420 together. The first adhesive layer 641 may be made of an epoxy polymer, a rubber polymer, or a polyolefin polymer, but is not limited thereto.

Referring to FIG. 6 , a first light blocking layer 651 is disposed between the first adhesive layer 641 and the first protective member 420 . The first light-blocking layer 651 is a component that overlaps and overlaps with the outside of the display panel 110 to block light from being viewed from the outside. The first light blocking layer 651 is disposed overlapping the outer portion of the display panel 110 in the non-display area NA of the display panel 110 . In addition, the lower surface and the inner surface of the first light blocking layer 651 may contact part of the upper surface of the first adhesive layer 641 and part of the side surface of the first adhesive layer 641 . Thus, the remaining part of the upper surface of the first light blocking layer 651 and the upper surface of the first adhesive layer 641 may be disposed on the same plane.

Also, the first light blocking layer 651 may be a black matrix. Accordingly, components disposed under the first light blocking layer 651 may be prevented from being viewed from the top of the first light blocking layer 651 . Accordingly, the non-display area NA of the display panel 110 overlapping the first light blocking layer 651 may not be visible from the top surface of the foldable display device 600 .

Referring to FIG. 6 , a second adhesive layer 642 is disposed between the first protection member 420 and the second protection member 430 . The second adhesive layer 642 is a component that bonds the first protection member 420 and the second protection member 430 together. The second adhesive layer 642 may be made of the same material as the adhesive layer 540 of FIG. 5 , and thus may have re-adhesiveness. Accordingly, the first protection member 420 and the second protection member 430 may be adhered to each other by the second adhesive layer 642 and may be separated from each other by an external force.

Referring to FIG. 6 , a second light blocking layer 652 is disposed between the second adhesive layer 642 and the second protection member 430 . The second light blocking layer 652 is a component that blocks components disposed outside the display panel 110 from being viewed from the outside. The second light blocking layer 652 is disposed to overlap the outer portion of the display panel 110 in the non-display area NA of the display panel 110 . In addition, the lower surface and the inner surface of the second light blocking layer 652 may contact part of the upper surface of the second adhesive layer 642 and part of the side surface of the second adhesive layer 642 . Accordingly, the remaining part of the upper surface of the second light blocking layer 652 and the upper surface of the second adhesive layer 642 may be disposed on the same plane.

Also, the second light blocking layer 652 may be made of the same material as the first light blocking layer 651 and may be a black matrix. Accordingly, components disposed under the second light blocking layer 652 may be prevented from being viewed from the top of the second light blocking layer 652 . Therefore, the non-display area NA of the display panel 110 overlapping the second light blocking layer 652 may not be visible from the top surface of the foldable display device 600 .

In the case of a conventional foldable display device, a single-layer light blocking layer overlapping the periphery of the display panel is disposed between the display panel and the protection member. The light blocking layer is formed on the lower surface of the protective member, and an adhesive resin constituting the adhesive layer is applied to the lower surface of the protective member and the lower surface of the light blocking layer. The adhesive resin covers the entire light blocking layer and the lower surface of the adhesive resin is flattened. applied in a thicker thickness. A display panel is disposed under the adhesive resin, and the adhesive resin is cured through a curing process. Accordingly, the light blocking layer is disposed on the same layer as the adhesive layer disposed between the display panel and the protective member, so that the lower surface and the inner surface of the light blocking layer are in contact with a part of the upper surface and a part of the side surface of the adhesive layer. Thus, the upper surface of the light blocking layer was disposed on the same plane as the rest of the upper surface of the adhesive layer.

At this time, the light blocking layer had to be formed to a specific thickness or more in order to prevent components disposed under the light blocking layer from being visually recognized from the outside. In addition, as the thickness of the light blocking layer increased, the adhesive resin had to be applied thickly so as to cover the entire light blocking layer and flatten the lower surface of the adhesive resin, and the thickness of the adhesive layer could be increased. Accordingly, in the case of a conventional foldable display, since the light blocking layer must be formed to a specific thickness or more, the thickness of the adhesive layer can be increased, and thus, the overall thickness of the foldable display can be increased.

In the case of the foldable display device 600 according to another embodiment of the present invention, one protection member is not disposed on the display panel 110, and the first protection member 420 and the second protection member 430 are arranged sequentially. Accordingly, the first light blocking layer 651 is disposed on the same layer as the first adhesive layer 641 bonding the first protective member 420 and the display panel 110, and the first protective member 420 and the second light blocking layer 651 are disposed on the same layer. A second light blocking layer 652 may be disposed on the same layer as the second adhesive layer 642 that adheres the protective member 430 thereto. That is, unlike conventional foldable displays, the light blocking layer may be divided and disposed on two different layers. In this case, the minimum thickness of the adhesive resin for flattening the lower surface of the first adhesive layer 641 covering the lower surface of the first protective member 420 and the lower surface and inner surface of the first light blocking layer 651 is reduced during the forming process. can In addition, the minimum thickness of the adhesive resin for flattening the lower surface of the second adhesive layer 642 covering the lower surface of the second protective member 430 and the lower surface and inner surface of the second light blocking layer 652 may be reduced during the forming process. there is. Therefore, compared to the case where the first light blocking layer 651 and the second light blocking layer 652 are disposed on the same layer as one light blocking layer like in a conventional foldable display, according to another embodiment of the present invention In the case of the foldable display 600, the first light blocking layer 651 and the second light blocking layer 652 may be separately disposed on different layers, so that the thickness of the adhesive layer of the conventional foldable display is larger than that of the conventional foldable display. According to another embodiment of the present invention, the sum of the thickness d4 of the first adhesive layer 641 and the thickness d5 of the second adhesive layer 642 may be reduced. Thus, the overall thickness of the foldable display device 600 can be reduced, and it can be folded more easily than the foldable display device 600 .

7 is a cross-sectional view of a foldable display device according to another exemplary embodiment of the present invention. The foldable display 700 of FIG. 7 is substantially the same as the foldable display 600 of FIG. 6 except that the second light-blocking layer 752 is different, and thus duplicate descriptions are omitted.

Referring to FIG. 7 , the second light blocking layer 752 may be a color filter. A color filter is a structure having a color other than black, and may refer to a structure that passes only light of a specific wavelength among light incident to the color filter. Second, a second protection member prevents components disposed under the second light blocking layer 752 from being viewed from the outside of the foldable display 700 and at the same time, from the outside of the foldable display 700 ( The color of the second light blocking layer 752 can be viewed through 430). For example, the second light blocking layer 752 may be a red color filter, and by the second light blocking layer 752 overlapping the outside of the display panel 110, the surface of the foldable display 700 is not visible. The display area NA may be red.

In the case of the foldable display device 700 according to another embodiment of the present invention, the second light blocking layer 752 may be a color filter, and thus, the display area AA of the foldable display device 700 is excluded. An outer area overlapping the second light blocking layer 752 in the non-display area NA may be viewed as the color of the color filter.

Also, in some embodiments, the second light blocking layer 752 may be a color pattern layer, unlike that shown in FIG. 7 . The color pattern layer may refer to a layer in which a pattern having a specific color is visible on the surface. Therefore, in the case of the foldable display device 700 according to another embodiment of the present invention, the second light blocking layer 752 is a color pattern layer, so that the outer area overlapping the second light blocking layer 752 is the second light difference. It can be recognized as a color pattern of the single layer 752 .

8 is a cross-sectional view of a foldable display device according to another exemplary embodiment of the present invention. The foldable display device 800 of FIG. 8 is substantially the same as the foldable display device 400 of FIG. 4 except that the phase retardation layer 850 is different, and thus duplicate descriptions are omitted.

Referring to FIG. 8 , a phase delay layer 850 is disposed between the first protection member 420 and the adhesive layer. The phase delay layer 850 is a component that delays the phase of light incident on one surface of the phase delay layer 850 . Specifically, the phase delay layer 850 may delay the phase of light incident on one surface by λ/4. Accordingly, a phase difference between light incident on one surface of the retardation layer 850 and light emitted on the other surface of the retardation layer 850 may be different by λ/4.

Also, the phase retardation layer 850 may be a liquid crystal coating layer, and may be formed of, for example, nematic liquid crystal. However, it is not limited thereto.

The display panel 110 of the foldable display 800 may include a polarization layer. The polarization layer refers to a layer that transmits light incident on one surface of the polarization layer as polarized light. Accordingly, light incident to the foldable display 800 from the outside is incident on the polarization layer of the display panel 110 and becomes polarized, and is reflected inside the display panel 110 and may not pass through the polarization layer. Accordingly, a phenomenon in which external objects are recognized on the surface of the foldable display device 800 may prevent reflection of external light.

In the case of a conventional foldable display, the display panel may include a polarization layer and not include a phase retardation layer. In this case, the image generated by the display panel may be linearly polarized light that passes through the polarization layer and oscillates on one axis. Thus, when viewing the image of the foldable display through polarizing glasses, the image is not visible and the image is black. It was a problem because it could only be observed.

Unlike this, in the case of the foldable display device 800 according to another embodiment of the present invention, the phase retardation layer 850 is disposed between the first protective member 420 and the adhesive layer, so that the foldable display device 800 Even if the image of is viewed through polarized glasses, the phenomenon of appearing black can be prevented. Specifically, as described above, the image passing through the polarization layer of the display panel 110 may be linearly polarized light vibrating along one axis. In this case, the linearly polarized light passes through the retardation layer 850 and the phase may be delayed by λ/4. Therefore, the image transmitted through the phase retardation layer 850 may be circularly polarized light whose oscillation axis is changed in different directions by 45° based on the oscillation axis of the linearly polarized light before transmission. That is, the image transmitted through the phase delay layer 850 may be circularly polarized light including light vibrating in two different axes. Accordingly, an image emitted from the foldable display 800 may be circularly polarized light, and a phenomenon in which an image is not visible and appears black when viewed through polarized glasses may be prevented.

A foldable display device according to embodiments of the present invention can be described as follows.

A foldable display device according to an exemplary embodiment of the present invention includes a display panel, a first protection member on the display panel, and a second protection member on the first protection member, wherein the modulus of the first protection member is greater than that of the second protection member. may be less than the modulus.

According to another feature of the present invention, the first protective member may include a plastic film and a reinforced coating layer disposed on at least one of upper and lower surfaces of the plastic film.

According to another feature of the present invention, the second protective member may include a glass substrate and a chemical reinforcement layer disposed on at least one of upper and lower surfaces of the glass substrate.

According to another feature of the present invention, the second protective member may include a shape memory polymer layer and a chemical reinforcement layer disposed on at least one of upper and lower surfaces of the shape memory polymer layer.

According to another feature of the present invention, the foldable display device includes a first adhesive layer disposed between the display panel and the first protection member to adhere the display panel and the first protection member, and between the first protection member and the second protection member. It may further include a second adhesive layer disposed to adhere the first protection member and the second protection member.

According to another feature of the present invention, the adhesive force of the second adhesive layer may be 100 gf / inch or less.

According to another feature of the present invention, the foldable display device includes a first light blocking layer disposed between the display panel and the first protection member overlapping the outer edge of the display panel and a first light blocking layer between the first protection member and the second protection member. A second light blocking layer disposed overlapping with the light blocking layer may be further included.

According to another feature of the present invention, the first light blocking layer may be a black matrix, and the second light blocking layer may be a black matrix, color filter or color pattern layer.

According to another feature of the present invention, the inner surface and lower surface of the first light blocking layer may contact the first adhesive layer, and the inner surface and lower surface of the second light blocking layer may contact the second adhesive layer.

According to another feature of the present invention, the foldable display device further includes a phase retardation layer disposed between the first protection member and the second protection member, and the phase retardation layer includes phase delay of light incident on one side of the phase retardation layer. can be delayed by λ/4.

A foldable display device according to another embodiment of the present invention includes a display panel and a first protection member and a second protection member disposed on the display panel, wherein the first protection member has a folding characteristic greater than that of the second protection member. It is a protection member for improving, and the second protection member may be a protection member for improving impact resistance than the first protection member.

According to another feature of the present invention, the first protection member is disposed closer to the display panel than the second protection member, so that the foldable display device can be configured to be out-folded.

According to another feature of the present invention, the second protective member may further include a chemical reinforcement layer disposed on at least one of the upper and lower surfaces.

According to another feature of the present invention, the first protective member may further include a reinforced coating layer disposed on at least one of the upper and lower surfaces.

According to another feature of the present invention, a reworkable adhesive layer may be disposed between the first protection member and the second protection member to separate or attach the first protection member and the second protection member to each other.

According to another feature of the present invention, the foldable display device further includes a light blocking layer that is disposed on the same layer as the re-adhesive adhesive layer and overlaps the periphery of the display panel, and the light blocking layer may have a color or pattern.

Although the embodiments of the present invention have been described in more detail with reference to the accompanying drawings, the present invention is not necessarily limited to these embodiments, and may be variously modified without departing from the technical spirit of the present invention. . Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. The protection scope of the present invention should be construed according to the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

100, 400, 500, 600, 700, 800: foldable display device
110: display panel
120, 420: first protection member
130, 430: second protection member
421: first base member
422: first reinforced coating layer
423: second reinforced coating layer
431: second base member
432: first chemical enhancement layer
433: second chemical enhancement layer
540: adhesive layer
641: first adhesive layer
642: second adhesive layer
651: first light blocking layer
652, 752: second light blocking layer
850: phase delay layer
AA: display area
NA: non-display area

Claims (17)

display panel;
a first protective member disposed on the display panel and including a plastic film and a reinforced coating layer disposed on at least one of upper and lower surfaces of the plastic film;
a second protection member positioned on the first protection member and including a glass substrate;
a first adhesive layer disposed between the display panel and the first protection member to adhere the display panel and the first protection member; and
a second adhesive layer disposed between the first protection member and the second protection member to adhere the first protection member and the second protection member;
A modulus of the first protection member is smaller than a modulus of the second protection member. delete According to claim 1,
The second protection member further includes a chemical strengthening layer disposed on at least one of an upper surface and a lower surface of the glass substrate. delete delete According to claim 1,
The second adhesive layer has an adhesive strength of 100 gf/inch or less. According to claim 1,
a first light blocking layer disposed between the display panel and the first protection member and overlapping an outer portion of the display panel; and
The foldable display device of claim 1, further comprising a second light blocking layer overlapping the first light blocking layer and disposed between the first protection member and the second protection member. According to claim 7,
The first light blocking layer is a black matrix,
The second light blocking layer is a black matrix, a color filter or a color pattern layer. According to claim 7,
The inner and lower surfaces of the first light blocking layer are in contact with the first adhesive layer,
The foldable display device of claim 1 , wherein inner and lower surfaces of the second light blocking layer contact the second adhesive layer. According to claim 1,
Further comprising a phase delay layer disposed between the first protection member and the second protection member,
The retardation layer delays a phase of light incident on one side of the retardation layer by λ/4. According to claim 1,
The first protection member is a protection member for improving folding characteristics than the second protection member,
The second protection member is a protection member for improving impact resistance compared to the first protection member, the foldable display device. According to claim 1,
The foldable display device of claim 1 , wherein the first protection member is disposed closer to the display panel than the second protection member, so that the foldable display device is capable of being out-folded. delete delete According to claim 1,
The second adhesive layer is a reworkable adhesive layer. display panel;
a first protection member on the display panel; and
a second protection member on the first protection member;
The modulus of the first protection member is smaller than the modulus of the second protection member;
The first protective member includes a plastic film and a reinforced coating layer disposed on at least one of upper and lower surfaces of the plastic film,
The second protection member includes a shape memory polymer layer. According to claim 16,
The second protection member further includes a chemical reinforcement layer disposed on at least one of upper and lower surfaces of the shape memory polymer layer.

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