Display apparatus

A display apparatus includes a display panel which is foldable at a folding area thereof; a foldable support which faces the display panel and is foldable together with the display panel; an elastic sheet between the foldable support and the display panel; a lower adhesive layer which is between the foldable support and the elastic sheet, and attaches the foldable support to the elastic sheet; and an upper adhesive layer which is between the elastic sheet and the display panel and attaches the elastic sheet to the display panel. Each of the foldable support, the elastic sheet, the lower adhesive layer and the upper adhesive layer is disconnected at the folding area.

This application claims priority to Korean Patent Application No. 10-2019-0126832 filed on Oct. 14, 2019, and all the benefits accruing therefrom under 35 U.S.C. § 119, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

Embodiments relate generally to a display apparatus. More particularly, embodiments relate to an in-folding type foldable display apparatus.

2. Description of the Related Art

A foldable display apparatus, which uses a flexible display panel that is bendable, has been developed. Since the display apparatus which is foldable can facilitate portability when folded and can implement a large screen when unfolded, the display apparatus may be applied to various fields for mobile devices such as mobile phones, ultra-mobile personal computers (“PCs”), electronic books and electronic newspapers as well as televisions, display monitors and the like.

The display apparatus may include a folding area disposed between non-folding areas spaced apart from each other. When the display apparatus is folded, a bent shape of the folding area may determine an overall volume or design of the display apparatus in the folded state thereof. Particularly, the bent shape of the folding area relates to an occurrence of wrinkles that spoil aesthetics of the folding area, in an unfolded state of the display apparatus. Accordingly, there have been demands for a foldable display apparatus having improved design and quality.

SUMMARY

One or more embodiment provides a foldable display apparatus having improved quality.

According to an embodiment, a display apparatus includes a display panel which is foldable at a folding area thereof, a foldable support which faces the display panel and is foldable together with the display panel; an elastic sheet between the foldable support and the display panel; a lower adhesive layer which is between the foldable support and the elastic sheet, and attaches the foldable support to the elastic sheet; and an upper adhesive layer which is between the elastic sheet and the display panel and attaches the elastic sheet to the display panel. Each of the foldable support, the elastic sheet, the lower adhesive layer and the upper adhesive layer is disconnected at the folding area.

In an embodiment, a width of a lower unattached area in which the elastic sheet and the foldable support are not bonded to each other, may be greater than a width of an upper unattached area in which the elastic sheet and the display panel are not bonded to each other.

In an embodiment, the upper unattached area may exclude the upper adhesive layer.

In an embodiment, the display apparatus may further include a step compensation layer disposed between the display panel and the elastic sheet, in the upper unattached area.

In an embodiment, an adhesive strength (or adhesive force) of a planar area of a surface of the upper adhesive layer which contacts the display panel, may be weaker than an adhesive strength of remaining portions of the surface of the upper adhesive layer, in the upper unattached area.

In an embodiment, the foldable support which is disconnected, may include a first support and a second support spaced apart from each other along the display panel, at the folding area, the display panel which is unfolded may dispose the first support and the second support coplanar with each other, and the display panel which is folded may dispose the first support and the second support facing each other.

In an embodiment, the display panel may include a first non-folding area corresponding to the first support, a second non-folding area corresponding to the second support, and a folding area between the first non-folding area and the second non-folding area. In addition, the foldable support which is folded together with the display panel, may dispose the display panel bent at the folding area.

In an embodiment, the elastic sheet which is disconnected, may include a first elastic sheet corresponding to the first non-folding area, and a second elastic sheet corresponding to the second non-folding area and spaced apart from the first elastic sheet along the display panel, at the folding area, the first elastic sheet may include a first portion corresponding to the folding area and a second portion which is adjacent to the first portion and corresponding to the first non-folding area, and the foldable support which is folded together with the display panel, may dispose the first portion of the first elastic sheet inclined with respect to the second portion of the first elastic sheet.

In an embodiment, the display panel which is unfolded, may define a space between the foldable support and the elastic sheet, in the lower unattached area.

In an embodiment, the foldable support may include a first support which faces the display panel and is foldable together with the display panel, the first support facing the elastic sheet with the space therebetween, and a second support in the space between the first support and the elastic sheet, the second support rotatably connected to the first support to rotate within an angle with respect to the first support.

In an embodiment, the elastic sheet may be attached to the foldable support at the second support.

In an embodiment, the display panel may include a first non-folding area, a second non-folding area, the folding area between the first non-folding area and the second non-folding area and at the folding area, an upper unattached area in which the elastic sheet and the display panel are unattached to each other, the upper unattached area having a width defined along the display panel. In addition, the foldable support which is folded together with the display panel, may define a radius of curvature of the display panel at the folding area, and the width of the upper unattached area may be about 10 times or less of the radius of curvature of the display panel.

In an embodiment, the foldable support may further include a central support disposed between the first support and the second support. The display panel which unfolded, may dispose a first elastic sheet and a second elastic sheet extended further than a side surface of the first support and the second support, respectively, at the folding area, and the first elastic sheet and the second elastic sheet which are extended further than the side surface of the first support and the second support, respectively, may define ends of the elastic sheet at the folding area which correspond to the central support.

In an embodiment, the elastic sheet may have an elastic modulus between about 5 gigapascals (GPa) and about 300 GPa.

In an embodiment, the elastic sheet may include a metal sheet having a thickness between about 30 micrometers (μm) and about 200 μm.

According to an embodiment, a display apparatus includes an elastic sheet which is foldable and has an elastic modulus between about 5 gigapascals and about 300 gigapascals; and a display panel facing the elastic sheet which has the elastic modulus between about 5 GPa and about 300 GPa, and is foldable together with the elastic sheet.

In an embodiment, the display apparatus may further include an upper adhesive layer which is between the elastic sheet and the display panel and attaches the elastic sheet to the display panel.

In an embodiment, the display panel may include a first non-folding area, a second non-folding area, a folding area between the first non-folding area and the second non-folding area and an upper unattached area in which the display panel and the elastic sheet are not bonded to each other, in the folding area.

In an embodiment, the display apparatus may further include a foldable support facing the display panel with the elastic sheet and the upper adhesive layer therebetween, the foldable support being foldable together with the display panel and the elastic sheet, and a lower adhesive layer which is between the foldable support and the elastic sheet and attaches the foldable support to the elastic sheet. The display panel which is unfolded, may dispose each of the elastic layer, the upper adhesive layer, the foldable support and the lower adhesive layer disconnected at the folding area.

In an embodiment, the foldable support which is unfolded together with the display panel, may define the upper unattached area having a width along the display panel, the foldable support which is folded together with the display panel, may define a radius of curvature of the display panel at the folding area, and the width of the upper unattached area may be about 10 times or less of the radius of curvature of the display panel.

Therefore, one or more embodiment of a display apparatus may include an elastic sheet and a flexible display panel which faces the elastic sheet. A rapidly deformed portion of the flexible display panel may be reduced by the elastic sheet, thereby minimizing or reducing an area in which wrinkles occur in the flexible display panel due to repeated folding and unfolding thereof. As a result, visual recognition of the wrinkles from outside the display apparatus may be reduced or effectively prevented.

DETAILED DESCRIPTION

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

FIG.1is a schematic perspective diagram illustrating an embodiment of a display apparatus which is unfolded, andFIG.2is a schematic perspective diagram illustrating of an embodiment of the display apparatus ofFIG.1which is folded.

Referring toFIGS.1and2, the display apparatus may include a foldable support including a first support210, a second support220and a central support230(e.g., a third support), and a display panel DP which is flexible and supported by the foldable support. The display apparatus may be a foldable display apparatus that is foldable and unfoldable at a display area DA.

The display apparatus may include a first non-folding area RA1, a second non-folding area RA2spaced apart from and the first non-folding area RA1along a first direction D1, and a folding area FA disposed between the first non-folding area RA1and the second non-folding area RA2. A length of the folding area FA may extend along a second direction D2which crosses the first direction D1. In an embodiment, the first direction D1may be perpendicular to the second direction D2, without being limited thereto. Components of the display apparatus may include a first non-folding area RA1, a second non-folding area RA2and a folding area FA corresponding to those described above for the display apparatus.

The display area DA is a planar area at which an image is displayed, light is emitted, etc. The display area DA may be disposed at a front surface or display surface of the display apparatus, at a viewing side thereof. The front surface may include the display area DA and a non-display area (not shown) which is adjacent to the display area DA, such as surrounding the display area DA in the top plan view. The display area DA may be disposed in each of the first non-folding area RA1, the folding area FA and the second non-folding area RA2.

According to one or more embodiment of the display apparatus, the display apparatus may be foldable at the folding area FA, to be bent (e.g., folded) and unbent (e.g., unfolded). An in-folding type foldable display apparatus may be implemented in which portions of the front surface or display surface face each other. The display apparatus may be non-foldable or may remain flat at the first non-folding area RA1and the second non-folding area RA2.

Referring toFIG.1the display area DA and each of the first non-folding area RA1and the second non-folding area RA2are disposed in a plane defined by the first direction D1and the second direction D2(e.g., coplanar with each other), for the display apparatus which is unfolded. Referring toFIG.2, that the first non-folding area RA1and the second non-folding area RA2are disposed in planes which are parallel with a plane defined by the second direction D2and a third direction D3which crosses each of the first direction D1and the second direction D2, for the display apparatus which is folded. In an embodiment, the third direction D3may be perpendicular to each of the first direction D1and the second direction D2, without being limited thereto. A thickness or thickness direction of the display apparatus and/or components thereof, may be defined along the third direction D3.

FIG.3is an enlarged cross-sectional view illustrating an embodiment of a folding area FA and an area adjacent thereto, in the display apparatus ofFIG.1which is unfolded, andFIG.4is an enlarged cross-sectional view illustrating an embodiment of a folding area FA and an area adjacent thereto, in the display apparatus ofFIG.3, which is folded.FIG.3is a view of an end portion of the display apparatus, at which the folding area FA is bent.

Referring toFIGS.3and4, the display apparatus may include a foldable support, a first lower adhesive layer112, a second lower adhesive layer114, a first elastic sheet102(e.g., first elastic layer), a second elastic sheet104(e.g., second elastic layer), a first upper adhesive layer122, a second upper adhesive layer124, and a display panel DP which is flexible.

The foldable support may include a first support210, a second support220and a central support230. The foldable support is disconnected at the folding area FA.

The display panel DP may be foldable to dispose the first support210and the second support220facing, and may be unfoldable to dispose the first support210and the second support220in planes which are parallel to each other (e.g., coplanar with each other). In an embodiment, for example, the first support210may be rotatable about a first rotation axis RX1, and the second support220may be rotatable about a second rotation axis RX2. That is, the first support210is rotatable relative to the central support230, about the first rotation axis RX1, and the second support220is rotatable relative to the central support230, about the second rotation axis RX2.

The display apparatus which is flat or unfolded, disposes the foldable support flat or unfolded. The foldable support which is flat or unfolded, disposes the central support230between the first support210and the second support220along the first direction D1, and may support ends of the first elastic sheet102and the second elastic sheet104. The foldable support which is flat or unfolded, disposes ends of the first elastic sheet102and the second elastic sheet104spaced apart from each other at the folding area FA. The ends define side surfaces of the first elastic sheet102and the second elastic sheet104which face each other at the folding area FA. Referring toFIG.3, for example, the display panel DP which unfolded, disposes the first elastic sheet102and the second elastic sheet104extended further than a side surface of the first support210and the second support220, respectively, at the folding area FA. The first elastic sheet102and the second elastic sheet104which are extended further than the side surface of the first support210and the second support220, respectively, define ends of a collective elastic sheet at the folding area FA, which correspond to the central support230.

Although the foldable support is illustrated relative to a two-axis hinge (e.g., the first rotation axis RX1and the second rotation axis RX2), the invention is not limited thereto. In an embodiment, for example, the foldable support may have a one-axis hinged structure.

The first elastic sheet102may be disposed on and corresponding to the first support210. The second elastic sheet104may be disposed on and corresponding to the second support220and may be spaced apart from the first elastic sheet102. The first elastic sheet102and the second elastic sheet104may support the folding area FA of the display panel DP which is unfolded. Accordingly, the display panel DP which is flat or unfolded, disposes each of the first elastic sheet102and the second elastic sheet104flat or unfolded, to support the folding area FA of the display panel DP. The first elastic sheet102and the second elastic sheet104may form a gap relative to the display panel DP, for allowing the display panel DP to be bent within the display apparatus which is folded.

The first elastic sheet102may include a material and a thickness that can reduce or effectively prevent a creep deformation from occurring, even after repeated folding and unfolding of the display apparatus and/or display panel DP In an embodiment, for example, an elastic modulus of the first elastic sheet102and the second elastic sheet104may be between about 5 gigapascals (GPa) and about 300 GPa. The first elastic sheet102and the second elastic sheet104may include a metal material (e.g., a metal sheet) and may have a thickness between about 30 micrometers (μm) and about 200 μm. In an embodiment, for example, the metal sheet may include stainless steel (SUS) or aluminum.

The first elastic sheet102and the second elastic sheet104may reduce or effectively prevent a bending deformation of the folding area FA of the display panel DP from increasing. The first elastic sheet102and the second elastic sheet104may together define a elastic sheet which is collectively between the first support210and the display panel DP and between the second support220and the display panel DP, the elastic sheet being disconnected at the folding area FA.

Referring toFIGS.3and4, the first elastic sheet102includes a first portion corresponding to the folding area FA and a second portion which is adjacent to the first portion and corresponding to the first non-folding area RA1. The foldable support which is folded together with the display panel DP (FIG.4), disposes the first portion of the first elastic sheet102inclined with respect to the second portion of the first elastic sheet102. Similar description may be applied to the second elastic sheet104shown inFIG.4.

In the display panel DP which is folded, the first non-folding area RA1and the second non-folding area RA2may be positioned to face each other, and the folding area FA of the display panel DP which is folded may be bent to have a water droplet shape as shown inFIG.4. Due to the first elastic sheet102and the second elastic sheet104, a length of a section of the display apparatus in which the deformation of the display panel DP occurs, may be reduced as compared to a display apparatus which omits the first elastic sheet102and the second elastic sheet104. In other words, due to the first elastic sheet102and the second elastic sheet104, a portion of a display apparatus in which the display panel DP is deformed may be reduced to a portion at an upper unattached area corresponding to a first width W1(FIG.3), as compared to the display apparatus which omits the first elastic sheet102and the second elastic sheet104, for which the deformed portion of the display panel DP would correspond to a secondary width. Accordingly, a planar area of the display panel DP which has wrinkles due to repeated folding and unfolding of the display panel DP may be minimized, so the wrinkles being visually recognizable from outside the display apparatus may be avoided.

The first lower adhesive layer112may be disposed between the first support210and the first elastic sheet102. That is, the first support210may face the first elastic sheet102with the first lower adhesive layer112therebetween. The second lower adhesive layer114may be disposed between the second support220and the second elastic sheet104. That is, the second support220may face the second elastic sheet104with the second lower adhesive layer114therebetween. The first lower adhesive layer112and the second lower adhesive layer114may bond the first elastic sheet102and the second elastic sheet104to the first support210and the second support220, respectively. The first lower adhesive layer112and the second lower adhesive layer114may together define a lower adhesive layer which is collectively between the elastic sheet and the foldable support, the lower adhesive layer being disconnected at the folding area FA. In an embodiment, for example, the first lower adhesive layer112and the second lower adhesive layer114may include be formed of an adhesive such as acrylic-based resin or silicone-based resin or a pressure sensitive adhesive (“PSA”).

The display panel DP which is flexible may be disposed on and corresponding to both the first elastic sheet102and the second elastic sheet104. The display panel DP may include a light emitting structure for generating a light and/or emitting a light for displaying an image, and may be an organic light emitting display panel which is flexible. A laminated structure of the light emitting structure and the like within the display panel DP which is flexible will be described with reference toFIG.9.

The first upper adhesive layer122may be disposed between the display panel DP and the first elastic sheet102. The second upper adhesive layer124may be disposed between the display panel DP and the second elastic sheet104. That is, the first elastic sheet102and the second elastic sheet104each face the display panel DP, with the first upper adhesive layer122and the second upper adhesive layer124therebetween respectively. The first upper adhesive layer122and the second upper adhesive layer124may respectively bond the first elastic sheet102and the second elastic sheet104to the display panel DP. The first upper adhesive layer122and the second upper adhesive layer124may together define an upper adhesive layer which is collectively between the elastic sheet and the display panel DP, the upper adhesive layer being disconnected at the folding area FA. In an embodiment, for example, the first upper adhesive layer122and the second upper adhesive layer124may include or be formed of an adhesive such as acrylic-based resin or silicone-based resin or a pressure sensitive adhesive (“PSA”).

The first upper adhesive layer122and the second upper adhesive layer124may be spaced apart from each other, to form an upper unattached area in which the upper a first upper adhesive layer122and the second upper adhesive layer124are omitted. That is, the upper unattached area excludes the upper adhesive layer. The upper unattached area may be defined in the folding area FA, and include a planar area of the display panel DP at which the first upper adhesive layer122and the second upper adhesive layer124are omitted. The upper unattached area may include a total planar area of the first elastic sheet102and the second elastic sheet104at which the first upper adhesive layer122and the second upper adhesive layer124are omitted.

The display panel DP which is folded defines a radius of curvature at the folding area FA, at an end portion of the display panel DP (refer toFIG.4). The upper unattached area may have a first width W1(FIG.3) taken in a direction along the display panel DP (e.g., first direction D1inFIG.3). The first width W1may be equal to or less than about 10 times the radius of curvature of the display panel DP which is folded. In an embodiment, for example, when the radius of curvature is about 2.5 μm, the first width W1may be about 15 μm. In an embodiment, for example, when the radius of curvature is about 1.5 μm, the first width W1may be about 9.5 μm.

The first lower adhesive layer112and the second lower adhesive layer114may be spaced apart from each other to form an upper unattached area in which the first lower adhesive layer112and the second lower adhesive layer114are omitted. A lower unattached area may have a second width W2. The second width W2is greater than the first width W1.

In the display apparatus which is unfolded, a space SP provided in plurality (e.g., spaces SP) may be provided or formed between the first support210and the first elastic sheet102, and between the second support220and the second elastic sheet104, respectively, at the lower unattached area. The spaces SP may be provided or formed by a first inclined surface210aof the first support210and a second inclined surface220aof the second support220, together with side surfaces of the central support230, the first lower adhesive layer112and the second lower adhesive layer114, but the spaces SP are not limited thereto. In an embodiment, for example, the spaces SP may be provided or formed in a stepped shape instead of the first inclined surface210aand the second inclined surface220a. That is, a shape of the first support210and the second support220may define a shape of the spaces SP, without being limited thereto.

In the display apparatus which is folded, the folding area FA of the first elastic sheet102, the second elastic sheet104and the display panel DP may be bent to define a curvature in the spaces SP.

Although not shown, a cushion layer including or formed of a foam material, may be disposed between the display panel DP, and each of the first elastic sheet102and the second elastic sheet104, respectively, or between the first elastic sheet102and the second elastic sheet104and the first support210and the second support220, respectively.

Although not shown, a cover window which is transparent may be provided on an outer side of a display surface (an upper surface inFIG.3) of the display panel DP The cover window may protect the display panel DP from external impacts, scratches or the like, while forming an outer surface of the display apparatus. An image generated by the display panel DP is transmittable through the cover window to outside the display apparatus. In addition, although not shown, the display apparatus may further include a touch screen panel which detects an input (e.g., touch action, object in proximity, etc.), between the display panel DP and the cover window.

FIG.5is an enlarged cross-sectional view illustrating an embodiment of a folding area FA and an area adjacent thereto, in a display apparatus which is unfolded, andFIG.6is an enlarged cross-sectional view illustrating an embodiment of a folding area FA and an area adjacent thereto, in the display apparatus ofFIG.5which is folded.FIG.6is a view of an end portion of the display apparatus, at which the folding area FA is bent.

Referring toFIG.5, the display apparatus is substantially the same as the display apparatuses ofFIGS.3and4, except for a first rotary support212and a second rotary support122respectively connected to a central support230. Therefore, duplicate descriptions related thereto will not be repeated.

The display apparatus may include a first support210, a second support220, a central support230, a first lower adhesive layer112, a second lower adhesive layer114, a first elastic sheet102, a second elastic sheet104, a first upper adhesive layer122, a second upper adhesive layer124and a display panel DP which is flexible.

The first rotary support212and the second rotary support222may be disposed in a space SP between the first support210and the first elastic sheet102and a space SP between the second support220and the second elastic sheet104, respectively.

The first rotary support212may be rotatably connected to the first support210, to rotate within an angle with respect to the first support210. In an embodiment, for example, the first rotary support212may rotate within the angle, about a first axis A1defined in the space SP.

The second rotary support222may be rotatably connected to the second support220to rotate within an angle with respect to the second support220. In an embodiment, for example, the second rotary support222may rotate within the angle, about a second axis A2defined in the space SP.

In the display apparatus which is folded, the first rotary support212and the second rotary support222may be rotated together with the first support210and the second support220, respectively, such as by using an elastic member (not shown) or the like. Accordingly, in the display apparatus which is folded, spaces SP between the foldable support and the display panel DP, which allows the display panel DP to be bendable, may be provided or formed due to rotations of the first rotary support212and the second rotary support222. The elastic sheet (e.g., a collection of the first elastic sheet102and the second elastic sheet104) is attached to the foldable support at the first rotary support212and the second rotary support222(e.g., as a secondary support to the primary support of the first support210together with the second support220).

The display apparatus which is unfolded, disposes the central support230facing the display panel DP with the first rotary support212and the second rotary support222therebetween such that the central support230may support the first rotary support212and the second rotary support222thereon. The display apparatus which is unfolded disposes the first elastic sheet102and the second elastic sheet104corresponding to the first rotary support212and the second rotary support222, in planes which are parallel to each other (e.g., to be coplanar with each other). Within the display apparatus which is unfolded, the first support210, the second support and the central support230relative to each other, the first rotary support212and the second rotary support222relative to each other, the first lower adhesive layer112and the second lower adhesive layer114relative to each other, the first elastic sheet102and the second elastic sheet104relative to each other, and the first upper adhesive layer122and the second upper adhesive layer124relative to each other, may be coplanar, without being limited thereto.

FIG.7is an enlarged cross-sectional view illustrating an embodiment of a folding area FA and an area adjacent thereto, in a display apparatus which is unfolded.

Referring toFIG.7, the display apparatus is substantially the same as the display apparatuses ofFIGS.3and4, except for the upper and lower unattached areas. Although not shown, the display apparatus may further include a foldable support (see the first support210, the second support220and the central support230ofFIGS.1through6).

The display apparatus may include a first lower adhesive layer112, a second lower adhesive layer114, a first elastic sheet102, a second elastic sheet104, a first upper adhesive layer122, a second upper adhesive layer124and a display panel DP which is flexible.

A lower unattached area, in which the first elastic sheet102and the first support210are not bonded to each other, may be provided or formed. In an embodiment, for example, the lower unattached area may be provided or formed by defining a first lower unattached planar area112aas a partial planar area of a lower surface of the first lower adhesive layer112, such as through a surface-processing or the like. Although not shown, in another embodiment, the lower unattached planar area also may be provided or formed by surface-processing a partial area of an upper surface of the first lower adhesive layer112.

In an embodiment, for example, when the first lower adhesive layer112is a pressure sensitive adhesive sheet including an ultraviolet (“UV”) reactant, the first lower unattached planar area112ahaving an adhesive strength weaker than an adhesive strength of other portions of the first lower adhesive layer112may be provided or formed by irradiating ultraviolet rays to a portion of the first lower adhesive layer112corresponding to the first lower unattached planar area112aof the first lower adhesive layer112. In another embodiment, the first lower unattached planar area112amay be provided or formed by a silicone processing when the first lower adhesive layer112includes an acrylic-based adhesive and may be provided or formed by an acrylic processing when the first lower adhesive layer112includes a silicone-based adhesive.

Similarly, a lower unattached area may also be provided or formed in the second lower adhesive layer114. In an embodiment, for example, a second lower unattached planar area114bmay be provided formed on a partial planar area of a lower surface of the second lower adhesive layer114, such as through a surface-processing or the like. The first lower unattached planar area112aand the second lower unattached planar area114bmay each have an adhesive strength weaker than an adhesive strength of remaining portions of the first lower adhesive layer112and the second lower adhesive layer114, respectively. That is, the first lower adhesive layer112and the second lower adhesive layer114are detachable from the foldable support at the lower unattached planar areas thereof, such that the display panel DP is detached relative to the foldable support at such planar areas.

An upper unattached area, in which the first elastic sheet102and the display panel DP are not bonded to each other, may be provided or formed. In an embodiment, for example, the upper unattached area may be provided or formed by defining a first upper unattached planar area122aon a partial planar area of an upper surface of the first upper adhesive layer122, such as through a surface-processing or the like. Although not shown, in another embodiment, the upper unattached area may also be defined by surface-processing a partial planar area of a lower surface of the first upper adhesive layer122.

Similarly, an upper unattached area may also be provided or formed in the second upper adhesive layer124. In an embodiment, for example, a second upper unattached planar area124bmay be provided or formed on a partial planar area of the upper surface of the second upper adhesive layer124, such as through a surface-processing or the like. Although not shown, in another embodiment, the upper unattached area may also be defined by surface-processing a partial planar area of a lower surface of the second upper adhesive layer124. The first upper unattached planar area122aand the second upper unattached planar area124bmay each have an adhesive strength weaker than an adhesive strength of remaining portions of the first upper adhesive layer122and the second upper adhesive layer124, respectively. That is, the display panel DP is respectively detachable from the first upper adhesive layer122and the second upper adhesive layer124at the upper unattached planar areas thereof, such that the display panel DP is foldable at the folding area FA. The remaining portions of the first upper adhesive layer122and the second upper adhesive layer124may include an attached planar area which is adjacent to the first upper unattached planar area122aand the second upper unattached planar area124band attached to the display panel DP.

According to one or more embodiment, since the unattached area (e.g., lower and/or upper) is provided or formed by surface-processing one or more of the adhesive layers at the folding area FA thereof, a step difference due to the adhesive layers relative to other layers within the display apparatus may be minimized.

FIG.8is an enlarged cross-sectional view illustrating an embodiment of a folding area FA and an area adjacent thereto, in a display apparatus which is unfolded.

Referring toFIG.8, the display apparatus is substantially the same as the display apparatuses ofFIGS.3and4except for a step compensation layer. Although not shown, the display apparatus may further include a foldable support (see the first support210, the second support220and the central support230ofFIGS.1through6).

The display apparatus may include a first lower adhesive layer112, a second lower adhesive layer114, a first elastic sheet102, a second elastic sheet104, a first upper adhesive layer122, a second upper adhesive layer124, a display panel DP which is flexible, a first lower step compensation layer113, a second lower step compensation layer115, a first upper step compensation layer123and a second upper step compensation layer125.

The first lower step compensation layer113and the second lower step compensation layer115may occupy a space SP between portions of the foldable support and the elastic members (seeFIG.3) and compensate for steps formed by the first lower adhesive layer112and the second lower adhesive layer114spaced apart from each other at the lower unattached area, respectively. The first lower step compensation layer113and the second lower step compensation layer115may be detached from corresponding portions of the foldable support, such that such that the display panel DP is detached relative to the foldable support at planar areas corresponding to the first lower step compensation layer113and the second lower step compensation layer115.

The first upper step compensation layer123and the second upper step compensation layer125may occupy a gap between portions of the first elastic sheet102and the second elastic sheet104, relative to the display panel DP (seeFIG.3), and compensate for steps formed by the first upper adhesive layer122and the second upper adhesive layer124spaced apart from each other at the upper unattached area, respectively. The first upper step compensation layer123and the second upper step compensation layer125may be detached from corresponding portions of the display panel DP.

According to one or more embodiment, since the step compensation layer is provided or formed in one or more unattached area at the folding area FA of the display apparatus, a step difference due to one or more of the adhesive layers relative to other layers within the display apparatus may be minimized.

FIG.9is an enlarged cross-sectional view illustrating a portion of a display panel DP of the display apparatus ofFIG.3.

Referring toFIGS.9and3, the display panel DP may include a flexible substrate300, a thin film transistor TFT, a first insulating layer310, a second insulating layer320, a via insulating layer IVA, a pixel defining layer PDL, a light emitting element380(e.g., light emitting structure), an encapsulation layer (e.g., thin film encapsulation layer TFE), and the like. The thin film transistor TFT may include an active pattern ACT, a gate electrode GE, a source electrode SE and a drain electrode DE. The light emitting element380may include a first electrode381, alight emitting layer382, and a second electrode383.

A flexible substrate300including a transparent or opaque material may be provided. The flexible substrate300may be disposed on the first upper adhesive layer122and/or second upper adhesive layer124. The flexible substrate300may include or be formed of a transparent resin substrate. An example of the transparent resin substrate that may be used as the flexible substrate300includes a polyimide substrate. The polyimide substrate may include a first polyimide layer, a barrier film layer, a second polyimide layer, and the like. In an embodiment, the flexible substrate300may include a quartz substrate, a synthetic quartz substrate, a calcium fluoride substrate, a fluorine-doped (F-doped) quartz substrate, a soda-lime glass substrate, a non-alkali glass substrate, and the like.

Within the display panel DP, a buffer layer (not shown) may be disposed on the flexible substrate300. The buffer layer may reduce or effectively prevent metal atoms or impurities from diffusing into the thin film transistor TFT from the flexible substrate300. In an embodiment of a method of manufacturing the display panel DP, the buffer layer may allow the active pattern ACT to be have a uniform structure, by adjusting a heat transfer rate during crystallization process for providing or forming the active pattern ACT. In addition, when a surface of the flexible substrate300which faces the thin film encapsulation layer TFE is not uniform, the buffer layer may serve to compensate for the nonuniformity and improve the flatness of the surface of the flexible substrate300. Depending on a material and/or structure of the flexible substrate300, two or more buffer layers may be provided on the flexible substrate300or the buffer layer may be omitted. In an embodiment, for example, the buffer layer may include an organic material or an inorganic material.

The active pattern ACT may be disposed on the flexible substrate300. The active pattern ACT may include a metal oxide semiconductor, an inorganic semiconductor (such as amorphous silicon and poly silicon), an organic semiconductor, and the like. The active pattern ACT may have a source area, a drain area, and a channel area which is between the source area and the drain area in a direction along the flexible substrate300.

The first insulating layer310may be disposed on the active pattern ACT. In an embodiment, for example, the first insulating layer310may cover the active pattern ACT on the flexible substrate300, and may define a planar upper surface without generating a step around the active pattern ACT. The first insulating layer310may be disposed to have a uniform thickness along a profile of the active pattern ACT, while covering the active pattern ACT relative to the flexible substrate300. The first insulating layer310may include a silicon material, metal oxide, and the like. In an embodiment, for example, the first insulating layer310may include silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), silicon oxycarbide (SiOxCy), silicon carbonitride (SiCxNy), aluminum oxide (AlOx), aluminum nitride (AlNx), tantalum oxide (TaOx), hafnium oxide (HfOx), zirconium oxide (ZrOx), titanium oxide (TiOx), and the like. In an embodiment, the first insulating layer310may have a multi-layer structure including a plurality of insulating layers. In an embodiment, for example, the insulating layers within the active pattern ACT may have different thicknesses from each other and/or include different materials from each other.

Agate pattern including agate electrode GE, may be disposed on the first insulating layer310. The gate pattern may be disposed to overlap the channel area of the active pattern ACT. The gate electrode GE may include a metal material, an alloy, a metal nitride, a conductive metal oxide, a transparent conductive material, and the like. In an embodiment, for example, the gate electrode GE may include gold (Au), silver (Ag), aluminum (Al), tungsten (W), copper (Cu), platinum (Pt), nickel (Ni), titanium (Ti), palladium (Pd), magnesium (Mg), calcium (Ca), lithium (Li), chromium (Cr), tantalum (Ta), molybdenum (Mo), scandium (Sc), neodymium (Nd), iridium (Ir), an alloy including aluminum, aluminum nitride (AlNx), an alloy including silver, tungsten nitride (WNx), an alloy including copper, an alloy including molybdenum, titanium nitride (TiNx), chromium nitride (CrNx), tantalum nitride (TaNx), strontium ruthenium oxide (SrRuxOy), zinc oxide (ZnOx), indium tin oxide (“ITO”), tin oxide (SnOx), indium oxide (InOx), gallium oxide (GaOx), indium zinc oxide (“IZO”), and the like. These may be used individually or in combination. In an embodiment, the gate pattern may include a multi-layer structure including a plurality of metal material layers. In an embodiment, for example, the metal material layers within the gate pattern may have different thicknesses from each other or include different materials from each other.

The second insulating layer320may be disposed on the gate pattern. In an embodiment, for example, the second insulating layer320may cover the gate pattern on the first insulating layer310, and may define a planar upper surface without generating a step around the gate pattern. The second insulating layer320may be disposed to have a uniform thickness along a profile of the gate pattern, while covering the gate pattern relative to the first insulating layer310. The second insulating layer320may include a silicon material, metal oxide, and the like. The second insulating layer320may have a multi-layer structure including a plurality of insulating layers. In an embodiment, for example, the insulating layers within the second insulating layer320may have different thicknesses from each other or include different materials from each other.

A data pattern including a source electrode SE and a drain electrode DE of the thin film transistor TFT, may be disposed on the second insulating layer320. The source electrode SE may be connected to the source area of the active pattern ACT at or through a contact hole provided in the first insulating layer310and the second insulating layer320, such as by removing first portions of material layers for forming the first insulating layer310and the second insulating layer320in a method of manufacturing the display panel DR The drain electrode DE may be connected to the drain area of the active pattern ACT at or through a contact hole provided in the first insulating layer310and the second insulating layer320, such as by removing second portions of material layers for forming the first insulating layer310and the second insulating layer320in a method of manufacturing the display panel DR The data pattern may include a metal material, an alloy, a metal nitride, a conductive metal oxide, a transparent conductive material, and the like. These may be used individually or in combination. In an embodiment, the data pattern may have a multi-layer structure including a plurality of metal material layers. In an embodiment, for example, the metal material layers within the data pattern may have different thicknesses from each other or include different materials from each other.

Accordingly, the thin film transistor TFT, which includes the active pattern ACT, the first insulating layer310, the gate electrode GE, the second insulating layer320, the source electrode SE and the drain electrode DE, may be provided on the flexible substrate300.

Although the thin film transistor TFT has been described as having a top gate structure, the invention is not limited thereto. In an embodiment, for example, the thin film transistor TFT may have a bottom gate structure, a double gate structure, or the like.

The via insulating layer VIA may be disposed on the second insulating layer320and the data pattern. In an embodiment, for example, the via insulating layer VIA may be disposed to have a relatively large thickness compared to other material layers on the flexible substrate300which form the display panel DR The via insulation layer VIA may have a substantially planar upper surface. In order to implement the above-described planar upper surface of the via insulation layer VIA, an embodiment of a method of manufacturing the display panel DP may include a planarization process added to in a process of providing the via insulation layer VIA. The via insulating layer VIA may be disposed to have a uniform thickness along a profile of the data pattern, in a direction along the second insulating layer320. The via insulating layer VIA may include or be formed of an organic material or an inorganic material. The via insulating layer VIA may include an organic material. In an embodiment, for example, the via insulating layer VIA may include photoresist, polyacryl-based resin, polyimide-based resin, polyamide-based resin, siloxane-based resin, acryl-based resin, epoxy-based resin, and the like.

The first electrode381may be disposed on the via insulating layer VIA. The first electrode381may be electrically connected to the thin film transistor TFT at or through a contact hole provided in the via insulating layer VIA, such as by removing a portion of a material layer for forming the via insulating layer VIA. The first electrode381may include a metal material, an alloy, a metal nitride, a conductive metal oxide, a transparent conductive material, and the like. These may be used individually or in combination. The first electrode381may have a multi-layer structure including a plurality of metal material layers. In an embodiment, for example, the metal material layers within the first electrode381may have different thicknesses from each other or include different materials from each other.

The pixel defining layer PDL may be disposed on the via insulating layer VIA. In an embodiment, for example, the pixel defining layer PDL may expose a portion of an upper surface of the first electrode381, while covering both of opposing side surfaces of the first electrode381. The pixel defining layer PDL may include or be formed of an organic material or an inorganic material. In an embodiment, the pixel defining layer PDL may include an organic material.

The light emitting layer382may be disposed on the pixel defining layer PDL and the first electrode381. The light emitting layer382may be provided or formed using a light emitting material capable of emitting a colored light (such as red light, green light, and blue light), different from each other according to display pixels or sub-pixels within a display pixel. The light emitting layer382may be provided or formed by laminating a plurality of light emitting materials respectively capable of generating different color light such as red light, green light and blue light, such that white light as a combination of colored light may be emitted at a display pixel or sub-pixel. A color filter (not shown) may be disposed on the light emitting layer382corresponding to the first electrode381. The color filter may include at least one of a red color filter, a green color filter and a blue color filter. The color filter may also include a yellow color filter, a cyan color filter or a magenta color filter. The color filter may include photosensitive resin or color photoresist.

The second electrode383may be disposed on the light emitting layer382and the pixel defining layer PDL. The second electrode383may include a metal material, an alloy, a metal nitride, a conductive metal oxide, a transparent conductive material, and the like. These may be used individually or in combination. The second electrode383may have a multi-layer structure including a plurality of layers. In an embodiment, for example, the metal material layers within the second electrode383may have different thicknesses from each other or include different materials from each other.

The thin film encapsulation layer TFE may be disposed on the second electrode383. The thin film encapsulation layer TFE may include at least one inorganic layer and organic layer that are arranged along a thickness direction of the display panel DP In an embodiment, for example, a first inorganic layer, an organic layer on the first inorganic layer, and a second inorganic layer on the organic layer may be included within the thin film encapsulation layer TFE. The thin film encapsulation layer TFE may reduce or effectively prevent deterioration of the light emitting layer382due to the permeation of the moisture, oxygen, or the like. In addition, the thin film encapsulation layer TFE may also function to protect the display panel DP from an external impact. In addition, the thin film encapsulation layer TFE may improve the flatness of the display panel DP at a viewing side thereof.

Although the display apparatus has been described as including an organic light emitting display panel, the invention is not limited thereto. In an embodiment, the display apparatus may include a liquid crystal display apparatus (“LCD”), a field emission display (“FED”), a plasma display panel (“PDP”) or an electrophoretic display apparatus (“EPD”).

FIG.10is a block diagram illustrating an embodiment of an electronic apparatus including a display apparatus.

Referring toFIG.10, the electronic apparatus500may include a processor510, a memory device520, a storage device530, an input/output (“I/O”) device540, a power supply550, and a display device560. Here, the display device560may be the display apparatus ofFIG.1. In addition, the electronic apparatus500may further include a plurality of ports for electronically and/or physically communicating with a video card, a sound card, a memory card, a universal serial bus (“USB”) device, other electronic apparatuses, etc. In an embodiment, the electronic apparatus500may be implemented as a smart phone. In another embodiment, the electronic apparatus500may be implemented as a television. However, the electronic apparatus500is not limited thereto. In an embodiment, for example, the electronic apparatus500may be implemented as a cellular phone, a video phone, a smart pad, a smart watch, a tablet personal computer (“PC”), a car navigation system, a computer monitor, a laptop, a head mounted display (“HMD”) apparatus, etc.

The processor510may perform various computing or operational functions. The processor510may be a micro-processor, a central processing unit (“CPU”), an application processor (“AP”), etc. The processor510may be coupled to other components via an address bus, a control bus, a data bus, etc. Further, the processor510may be coupled to an extended bus such as a peripheral component interconnection (“PCI”) bus. The memory device520may store data for operations of the electronic apparatus500. In an embodiment, for example, the memory device520may include at least one non-volatile memory device such as an erasable programmable read-only memory (“EPROM”) device, an electrically erasable programmable read-only memory (“EEPROM”) device, a flash memory device, a phase change random access memory (“PRAM”) device, a resistance random access memory (“RRAM”) device, a nano floating gate memory (“NFGM”) device, a polymer random access memory (“PoRAM”) device, a magnetic random access memory (“MRAM”) device, a ferroelectric random access memory (“FRAM”) device, etc. and/or at least one volatile memory device such as a dynamic random access memory (“DRAM”) device, a static random access memory (“SRAM”) device, a mobile DRAM device, etc. The storage device530may include a solid state drive (“SSD”) device, a hard disk drive (“HDD”) device, a CD-ROM device, etc. The I/O device540may include an input device such as a keyboard, a keypad, a mouse device, a touch-pad, a touch-screen, etc., and an output device such as a printer, a speaker, etc. The power supply550may provide power for operations of the electronic apparatus500.

The display device560may be coupled to other components via the buses or other communication links. In an embodiment, the I/O device540may include the display device560. As described above, the display device560may be a display apparatus which is foldable, that can be folded and unfolded. The display device560may include elastic sheets disposed between a display panel DP which is flexible, and the foldable support. The display device560may minimize an area in which wrinkles occur in the display panel DP which is flexible, due to repeated folding and unfolding, so that visual recognition of the wrinkles is reduced or effectively prevented. Since these are described above, duplicated description related thereto will not be repeated.

One or more embodiment of a display apparatus may be applied to an electronic apparatus500including the display apparatus. In an embodiment, for example, one or more embodiment of the display apparatus may be applied to a smart phone, a cellular phone, a video phone, a smart pad, a smart watch, a tablet PC, a car navigation system, a television, a computer monitor, a laptop, a head mounted display apparatus, etc.