KR20190044267A - Flexible display device - Google Patents

Abstract

Embodiments of the present invention provide a flexible display device comprising: a display module layer; a window disposed on the display module layer; and a first point adhesive layer disposed between the display module layer and the window. The first point adhesive layer has a specific range of bending adhesive modulus (BAM), and tensile modulus of one of the window and the display module layer has a specific value. Thus, residues can be prevented from generating due to poor adhesion of display elements such as the window, the display module layer, and the like, and damage of display elements can be prevented.

Description

[0001] FLEXIBLE DISPLAY DEVICE [0002]

The present invention relates to a flexible display device. More particularly, the present invention relates to a flexible display device including a plurality of layers stacked on a display panel.

Recently, display apparatuses capable of displaying information including image images are actively being developed. The display device may be a liquid crystal display (LCD) device, an organic light emitting diode (OLED) device, a plasma display panel (PDP) device, and a field emission display ) Device and the like.

In the display device, a window substrate for protecting the display panel from an external environment may be disposed on a display panel such as an LCD panel and an OLED panel. The flexible substrate and the display panel may include a transparent plastic material having flexibility, for example.

Further, additional members of a display device such as a polarizing plate and a touch screen panel may be disposed between the window substrate and the display panel. For example, external light reflected from the electrode pattern of the display panel can be blocked by the polarizing plate. Also, the user can input a command of the user through the screen by the touch screen panel.

However, as a plurality of layers or structures such as the polarizing plate, the touch screen panel, and the window substrate are stacked on the display panel, requirements in recent display devices such as flexible characteristics improvement and thinning are not easily implemented . Further, as the plurality of layers or structures are stacked, sufficient flexibility can not be easily ensured while preventing damages such as cracks and breaks of the structure in a bending or folding operation.

For example, Korean Patent Publication No. 2012-0076026 discloses a transparent substrate including a touch screen panel including a polarizing plate.

Korea Patent Publication No. 2012-0076026

An object of the present invention is to provide a flexible display device that is excellent in reworkability and can prevent damage to a display module layer.

It is also an object of the present invention to provide a flexible display device having improved flexibility and mechanical reliability.

1. display module layer; A window disposed on the display module layer; And a first point-of-attack layer disposed between the display module layer and the window, wherein the first point-of-attack layer is calculated according to the following equation (1) and has a Bending Adhesive Modulus (BAM) of 0.03 to 20 MPa And a tensile modulus of elasticity at 25 ° C of the window and the display module layer is 4,000 MPa or more. Flexible display device:

[Equation 1]

Bending Adhesion Modulus (BAM) = storage elastic modulus at 25 占 폚 of the pressure-sensitive adhesive layer /

(In the formula (1), the thickness ratio of the pressure-sensitive adhesive layer is a ratio of the thickness of the pressure-sensitive adhesive layer to the total thickness of the flexible display device).

2. The flexible display device according to claim 1, wherein a Neutral Plane is formed at an interface between the window and the display module layer having a tensile elastic modulus at 25 DEG C of 4,000 MPa or more and the first point- .

3. The flexible display device according to 1 above, wherein the thickness of the first adhesive layer is 10 to 100 mu m.

4. The flexible display device of claim 1, wherein the first point-sensitive adhesive layer is formed of an acrylic pressure sensitive adhesive (PSA) composition or an optically clear adhesive (OCA) composition.

5. The flexible display device according to 1 above, wherein the tensile elastic modulus at 25 ° C of the window and the display module layer is 4,000 MPa or more and the tensile elastic modulus at 25 ° C is less than 4,000 MPa.

6. The flexible display device of claim 1, wherein the window has a tensile elastic modulus at 25 캜 of 4,000 MPa or more and a tensile elastic modulus of the display module layer at 25 캜 of 4,000 MPa or less.

7. The flexible display device according to claim 1, wherein when the flexible display device is bent, a neutral plane is formed in each of the display module layer and the window.

8. The flexible display device of claim 1, wherein the first adhesive layer is in direct contact with the display module layer and the window.

9. The display module of claim 1, wherein the display module layer comprises: a display panel; A functional structure disposed on the display panel; And a second adhesive layer disposed between the display panel and the functional structure.

10. The flexible display device of claim 9, wherein the display panel comprises an organic light emitting diode (OLED) panel or a liquid crystal display (LCD) panel.

11. The flexible display device of claim 9, wherein the functional structure comprises at least one of a touch sensor or a polarizing layer.

12. The flexible display device of claim 9, wherein the second adhesive layer has a bending tackiness modulus of 0.03 to 20 MPa, and the tensile elastic modulus at 25 ° C of the functional structure and the display panel is 2,000 MPa or more.

13. The flexible display device according to claim 12, wherein a neutral plane is formed at the interface between any one of the functional structure and the display panel having the tensile elastic modulus at 25 DEG C of 4,000 MPa or more and the second point-adhesive layer.

14. The flexible display device according to claim 9, wherein when the flexible display device is bent, a neutral plane is formed inside the functional structure and the display panel, respectively.

In the flexible display device according to the embodiments of the present invention, the thickness of the viscous adhesive layers, the storage elastic modulus and the tensile elastic modulus of the display member are adjusted by inserting the viscous adhesive layers between the display members, The neutral plane can be formed at the interface of the point-adhesive layer in contact therewith. This makes it possible to prevent the display member from being damaged and prevent the display member from being damaged at the time of rework due to poor adhesion of the display member.

In addition, a neutral plane may be formed on each display member of the flexible display device, and even if stress such as folding or bending is applied to the flexible display device, the bending deformation and stress deformation of each display member by the neutral plane Can be minimized. For example, the flexible display device may include a display panel, a touch sensor layer, a polarizing layer, and / or a window layer. The flexible display device may include various wires, an insulating film, a sensing electrode, a polarizer, Defects such as stress damage, cracks, breakage, etc. of the structure including the cracks can be prevented.

1 is a schematic cross-sectional view showing a flexible display device according to exemplary embodiments;
2 is a schematic cross-sectional view showing a flexible display device according to some embodiments.
3 is a schematic cross-sectional view illustrating a display panel according to exemplary embodiments.
4 is a schematic plan view showing a touch sensor according to exemplary embodiments;

Embodiments of the present invention provide a flexible display device comprising a display module layer, a window disposed on the display module layer, and a first point-of-adhesion layer disposed between the display module layer and the window. The first point-of-use adhesive layer has a specific range of Bending Adhesive Modulus (BAM), and the tensile modulus of either the window or the display module layer has a specific value, It is possible to prevent the display member from being damaged and to prevent the display member from being damaged.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. And shall not be construed as limited to such matters.

1 is a schematic cross-sectional view showing a flexible display device according to exemplary embodiments;

Referring to FIG. 1, the flexible display device may include a display module layer 10 and a window 20.

The display module layer 10 may be, for example, a laminated structure of display members or various display members for implementing a flexible display device, and may include a display panel 100, a functional structure 200 ) May be laminated, and this will be described later.

For example, the window 20 may be exposed to the user-visible side of the flexible display device and provided as a protective film for the external environment.

The window 20 may comprise a flexible plastic material, or a substrate layer comprising a polymeric material. For example, the substrate layer may be formed of a material selected from the group consisting of polyimide (PI), polyethersulphone (PES), polyacrylate (PAR), polyetherimide (PEI), polyethyelenen napthalate (PEN), polyethyleneterephthalate (PET), polyphenylene sulfide (PPS), polyallylate, polycarbonate (PC), cellulose triacetate (TAC), cellulose acetate pro Cellulose acetate propionate (CAP), and the like. These may be used alone or in combination of two or more.

The window 20 may further comprise a hard coating layer formed on at least one side of the substrate layer. The hard coating layer is formed using a hard coating composition including, for example, a photo-curable compound, a photoinitiator and a solvent, thereby further securing excellent flexibility, abrasion resistance and surface hardness of the window 20. [

The photocurable compound may include, for example, a siloxane-based compound, an acrylate-based compound, a (meth) acryloyl group, or a compound having a vinyl group. These may be used alone or in combination of two or more.

The photoinitiator is not particularly limited as long as it initiates polymerization of the photo-curable compound by generating an ion, a Lewis acid or a radical by irradiation of an active energy ray such as visible light, ultraviolet light, X-ray or electron beam. Examples of the photoinitiator include aromatic diazonium salts, onium salts such as aromatic iodonium salts and aromatic sulfonium salts, acetophenone compounds, benzoin compounds, benzophenone compounds and thioxanthone compounds.

According to exemplary embodiments, a first adhesive layer 50 may be disposed between the display module layer 10 and the window 20. In some embodiments, the first point-of-use adhesive layer 50 may be in direct contact with the surfaces of the display module layer 10 and the window 20. For example, after forming the first point-of-sale adhesive layer 50 on the bottom surface of the window 20, the exposed surface of the first point-of-sale adhesive layer 50 may be attached to the upper surface of the display module layer 10.

The term " adhesive layer " used in the present application is used to mean an adhesive layer and an adhesive layer. The pressure-sensitive adhesive layer may be formed using a pressure sensitive adhesive (PSA) composition or an optically clear adhesive (OCA) composition.

The first adhesive layer 50 may have a viscoelastic characteristic applicable to a flexible display while having an appropriate adhesive strength so as not to cause peeling, bubbles, or the like when the flexible display device is bent. In some embodiments, the first point-of-use adhesive layer 50 may be formed using an acrylate-based PSA composition. For example, the PSA composition may include a (meth) acrylic acid ester copolymer, a crosslinking agent, and a solvent.

The type of the cross-linking agent is not particularly limited and may be appropriately selected from those commonly used in the art. For example, the crosslinking agent may include a polyisocyanate compound, an epoxy resin, a melamine resin, a urea resin, a dialdehyde, a methylol polymer and the like, and preferably a polyisocyanate compound may be used.

The solvent may include a conventional solvent used in the field of resin composition. Examples of the solvent include alcohols such as methanol, ethanol, isopropanol, butanol, propylene glycol methoxy alcohol, ketones such as methyl ethyl ketone, methyl butyl (Methyl acetate, ethyl acetate, butyl acetate, propylene glycol methoxy acetate and the like), cellosolve type (methyl cellosolve, ethyl cellosolve, propyl cellulose, ethyl cellosolve, Etc.), hydrocarbons (normal hexane, normal heptane, benzene, toluene, xylene, etc.) can be used. These may be used alone or in combination of two or more.

In exemplary embodiments, the first point-of-use adhesive layer 50 may have a Bending Adhesive Modulus (BAM) of 0.03 to 20 MPa, and the BAM may be calculated according to Equation 1 below.

[Equation 1]

Bending Adhesion Modulus (BAM) = storage elastic modulus at 25 占 폚 of the pressure-sensitive adhesive layer /

In the above formula (1), the thickness ratio of the pressure-sensitive adhesive layer can be defined by the following formula (1-1).

Thickness ratio of the pressure-sensitive adhesive layer = thickness of the pressure-sensitive adhesive layer / total thickness of the flexible display device

For example, the thickness ratio of the first adhesive layer 50 may be defined as a value obtained by dividing the thickness of the first adhesive layer 50 by the total thickness of the layered body shown in Fig.

The flexible display device according to the exemplary embodiments can effectively prevent breakage, cracks, damage, etc. of each display member or internal structure of the flexible display device by adjusting the BAM in the above-described range.

In some embodiments, the flexible display device having the BAM range described above may be formed with a neutral surface on each of the optical member or the information transfer member included therein. For example, when the flexible display device is bent, the neutral plane may be formed in the display module layer 10 and the window 20, respectively. Specifically, as shown in FIG. 1, when the flexible display device is bent, the display panel 100 and the functional structure 200 included in the window 20 and / or the display module layer 10, The planes NP2, NP3, and NP4 may be formed.

The term " neutral surface " as used in the present application is defined as a surface where the compressive stress and the tensile stress are substantially the same when the flexible display device is bent. Accordingly, the strain can be converged to substantially zero on the neutral plane.

When the flexible display device is bent, a compressive force is exerted on the inner side bent and a tensile force is exerted on the outer side, thereby damaging the internal structure.

According to exemplary embodiments, since each of the optical member or the information transferring member included in the flexible display device includes the neutral surface, the compressive force and the tensile force are internally offset to prevent the internal structure from being ruptured, cracked, have. Therefore, the flexible or bendable range of the flexible display device can be extended, so that flexibility and mechanical reliability can be improved.

When the BAM of the first point adhesive layer is less than about 0.03 MPa (for example, the thickness of the pressure-sensitive adhesive layer is excessively increased), the strain separation due to the first pressure-sensitive adhesive layers 50 is loosened or relaxed, It may not be implemented. When the BAM of the first point adhesive layer is more than about 20 MPa (for example, the storage modulus of the adhesive layer is excessively increased), sufficient adhesive force is not realized and peeling, bubbling, have.

In some embodiments, the BAM of the pressure-sensitive adhesive layer can be adjusted in the range of about 0.2 to 10 MPa in consideration of prevention of bending damage and stable adhesion.

The storage modulus and thickness of the first adhesive layer 50 can be adjusted within the range of the BAM, and are not particularly limited. For example, the thickness of each of the first adhesive layer 50 may be about 10 to 100 mu m.

In exemplary embodiments, the tensile modulus at 25 占 폚 of either the window 20 or the display module layer 10 may be greater than or equal to 4,000 MPa, and preferably from 4,000 MPa to 7,000 MPa. For example, in some embodiments, one of the window and the display module layers may have a tensile modulus of at least 4,000 MPa at 25 ° C and a tensile modulus at 25 ° C of less than 4,000 MPa.

The display member selected from among the display module layer 10 and the window 20 together with the above-described BAM range is adjusted to the above-described range of the tensile elastic modulus, and accordingly, when the rework or peeling is caused due to adhesion failure between the display members, The residue can be minimized and the damage of the display member can be effectively prevented. For example, as shown in FIG. 1, a neutral plane NP1 is formed at an interface between the window 20 and the display module layer 10 having a tensile elastic modulus at 25 ° C of 4,000 MPa or more and the first point- So that the compressive force and the tensile force can be canceled internally at the interface of the first point-peptive layer, so that it is possible to prevent the residue at the time of peeling due to rework, and to prevent the display member from being broken, cracked, or damaged.

For example, in some embodiments, of the window 20 and display module layer 10, the indicator member having a tensile modulus of at least 4,000 MPa at 25 캜 may be window 20, The display member having an elastic modulus of less than 4,000 MPa may be the display module layer 10 and the window 20 during rework may be peeled off from the display module layer 10 together with the first adhesive layer 50. Accordingly, the window 20 and the first adhesive layer 50 on the bottom surface thereof can be peeled together from the display module layer 10 and the adhesive material of the first adhesive layer 50 can be peeled off from the display module layer 10 ) Surface.

In some embodiments, either one of the window 20 and the display module layer 10 may have a tensile modulus of at least 4,000 MPa at 25 ° C and a tensile modulus at 25 ° C of less than 4,000 MPa, And preferably 1,000 to 3,500 MPa. In the above range, the neutral plane NP1 can be easily formed on the interface between the window 20 or the display module layer 10 and the first adhesive layer 50, desirable.

If the tensile modulus of elasticity of the window 20 and the display module layer 10 at 25 캜 is less than 4,000 MPa, the mechanical properties of the member can not be ensured, the member is damaged or broken, And the residue may remain on the surface of the display member at the time of peeling.

In some embodiments, the display module layer 10 may include the display panel 100 and the functional structure 200 disposed on the display panel 100, as shown in FIG.

The display panel 100 may include, for example, an organic light emitting diode (OLED) panel or a liquid crystal display (LCD) panel. The detailed structure and structure of the display panel 100 will be described later with reference to Fig.

The functional structure 200 may include, for example, at least one of a touch sensor or a polarizing layer. The detailed configuration and structure of the touch sensor will be described later with reference to Fig.

The polarizing layer may be provided, for example, as a polarizing plate including a stretched polarizer. In this case, the polarizing plate may include a polarizer and a protective film formed on at least one surface of the polarizer.

The elongated polarizer may include, for example, a stretched polyvinyl alcohol (PVA) based resin. The polyvinyl alcohol-based resin is preferably a polyvinyl alcohol-based resin obtained by saponifying a polyvinyl acetate-based resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of the other monomer include an acrylamide monomer having an unsaturated carboxylic acid type, an unsaturated sulfonic acid type, an olefin type, a vinyl ether type, and an ammonium group. The polyvinyl alcohol-based resin may be modified or may be polyvinyl formal or polyvinyl acetal modified with, for example, aldehydes.

Examples of the protective film include polyester resins such as polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate and polybutylene terephthalate; Cellulose-based resins such as diacetylcellulose and triacetylcellulose; Polycarbonate resin; Acrylic resins such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; A cyclic olefin-based polymer (COP), and the like.

The polarizing layer may comprise a coated polarizer. In this case, the polarizing layer may be coated directly on the touch sensor, and the functional structure 200 may include a laminated structure of the touch sensor and the polarizing layer. For example, the polarizing layer may include an alignment film and a liquid crystal layer formed on the alignment film.

For example, an alignment film coating composition containing an orienting polymer, a photopolymerization initiator and a solvent is applied and cured on the touch sensor to form the alignment film, and then a liquid crystal coating composition is applied and cured on the alignment film to form an alignment film and a liquid crystal A polarizing layer including a layer can be formed.

The oriented polymer may include, for example, a polyacrylate resin, a polyamic acid resin, a polyimide resin, a polymer including a cinnamate group, and the like. The liquid crystal coating composition may include a reactive liquid crystal compound and a dichroic dye.

In some embodiments, the thickness and tensile modulus of the functional structure 200 can be adjusted to facilitate the formation of a neutral plane therein, for example, in terms of easily forming the neutral plane of the display module layer 10 The thickness of the functional structure 200 may be 50 to 150 탆, and the tensile elastic modulus at 25 캜 may be 2,000 MPa or more.

In some embodiments, the flexible display device may further include a second adhesive layer 70 disposed between the display panel 100 and the functional structure 200. For example, the second adhesive layer 70 may be in direct contact with the display panel 100 and the functional structure 200 through which the display panel 100 and the functional structure 200 may be bonded.

The second adhesive layer 70 may be formed of the same material, method, or the like as the first adhesive layer 50 described above.

For example, the second adhesive layer 70 may have a BAM of 0.03 to 20 MPa, and the tensile elastic modulus at 25 ° C of the functional structure 200 and the display panel 100 may be 2,000 MPa or more. As shown in FIG. 1, for example, the display panel 100 and the functional structure 200 having a tensile elastic modulus at 25 ° C of 2,000 MPa or more and the second adhesive layer 70 are neutralized The surface NP5 may be formed and the residue of the second adhesive layer 70 is not left on the side where the display panel 100 and the functional structure 200 are adhered to each other during the reheating due to adhesion failure, The damage and breakage of the members to be peeled can be effectively prevented.

The tensile modulus of elasticity of the BAM of the second adhesive layer 70, the functional structure 200 and the display panel 100 at 25 DEG C is controlled within the above-described range, whereby the display panel 100 and the functional Neutral planes NP3 and NP4 may be formed in the structure 200, respectively, so that the compressive force and the tensile force are internally offset to prevent fracture, crack, and damage of the members.

2 is a schematic cross-sectional view showing a flexible display device according to some embodiments.

Referring to FIG. 2, the functional structure may include a touch sensor 200a and / or a polarizing layer 200b. Also, a third point-of-adhesion layer 90 may be formed between the touch sensor 200a and the polarizing layer 200b.

The third adhesive layer 90 may have a BAM (about 0.03 to 20 MPa) in the above-mentioned range. Strain separation between the touch sensor 200a and the polarizing layer 200b is promoted by the third point adhesive layer 90 so that the neutral faces NP4a and NP4b are formed inside the touch sensor 200a and the polarizing layer 200b, Can be formed. For example, a neutral plane NP4a may be formed inside the touch sensor 200a, and a neutral plane NP4b may be formed inside the polarization layer 200b.

The tensile modulus of elasticity at 25 DEG C of any one of the touch sensor 200a and the polarizing layer 200b together with BAM (about 0.03 to 20 MPa) in the above-mentioned range of the third point-bonding layer 90 is not less than 2,000 MPa The third adhesive layer 90 does not remain on the side to be peeled off during rework due to adhesion failure of the touch sensor 200a and the polarizing layer 200b and damage of the peeled and peeled members , Fracture can be effectively prevented.

3 is a schematic cross-sectional view illustrating a display panel according to exemplary embodiments.

3, the display panel 100 may include a thin film transistor (TFT), insulating layers, a pixel electrode 145, and a display layer 160 disposed on a panel substrate 105.

The panel substrate 105 may be provided as a base substrate of the display panel 100. The panel substrate 105 may include a flexible resin material such as, for example, polyimide.

The thin film transistor may include an active layer 110, a gate electrode 120, a source electrode 132, and a drain electrode 134. The insulating structure may include a gate insulating film 115, an interlayer insulating film 125, and a via insulating film 140.

The active layer 110 is formed on the upper surface of the panel substrate 105 and may include polysilicon or an oxide semiconductor (for example, indium gallium zinc oxide (IGZO) or the like). The gate insulating layer 115 may be formed on the panel substrate 105 to cover the active layer 110.

The gate electrode 120 may be disposed on the gate insulating film 115 and overlapped with the active layer 110. The gate electrode 120 may include a metal such as Al, Ti, Cu, W, Ta, or Ag.

An interlayer insulating film 125 that covers the gate electrode 120 is formed on the gate insulating film 115 and then the source electrode 132 is formed in contact with the active layer 110 through the interlayer insulating film 125 and the gate insulating film 115, And the drain electrode 134 can be formed. The source electrode 132 and the drain electrode 134 may be formed to include a metal such as Al, Ti, Cu, W, Ta, Ag, or the like.

A via insulating film 140 covering the source electrode 132 and the drain electrode 134 may be formed on the interlayer insulating film 125. [ The via insulating layer 140 may be formed using an organic insulating material such as an acrylic resin, a siloxane resin, or the like.

A pixel electrode 145 electrically connected to the drain electrode 134 may be formed on the via insulating layer 140. The pixel electrode 145 may include a via portion that contacts the drain electrode 134 through the via insulating layer 140. The pixel electrode 145 may be formed to include a metal such as Al, Ti, Cu, W, Ta, Ag, and / or a transparent conductive oxide (e.g., indium tin oxide (ITO)).

The pixel defining layer 150 may be formed on the via insulating layer 140 and the display layer 160 may be formed on the pixel electrode 145 exposed by the pixel defining layer 150. The display layer 160 may be formed of, for example, a liquid crystal layer included in an organic light emitting layer (EML) or an LCD device included in an OLED device.

The counter electrode 170 may be formed on the pixel defining layer 150 and the display layer 160. The counter electrode 170 may be provided as a common electrode, a reflective electrode, or a cathode of an image display apparatus.

The display panel 100 includes a plurality of pixels, and the thin film transistor and the pixel electrode 145 may be arranged for each pixel. The counter electrode 170 may be provided as a common electrode that continuously extends over a plurality of pixels.

An encapsulation layer 180 may be formed on the counter electrode 170. The encapsulation layer 180 may comprise an inorganic insulating material such as silicon oxide, silicon nitride, and / or organic insulating materials such as acrylic, siloxane, urethane, and the like.

The display panel 100 may further include a pixel circuit electrically connected to the thin film transistor. For example, the pixel circuit includes a data line, a scan line, a power supply line, and the like, and each pixel can be defined for each crossing region of the data line and the scan line.

As described above, the neutral plane NP3 is formed inside the display panel 100 as shown in FIG. 1 or FIG. 2, and damage such as cracking or breakage of the pixel circuit, thin film transistor, Can be suppressed.

The thickness and tensile modulus of the display panel 100 may be adjusted to facilitate the formation of the neutral surface therein, for example, in order to easily implement the neutral surface of the display module layer 10, the display panel 100 ) May be about 80 to 400 탆, and the tensile elastic modulus at 25 캜 may be 3,000 MPa or more.

4 is a schematic plan view showing a touch sensor according to exemplary embodiments; For example, the touch sensor may be applied as the functional structure 200 in the form of a touch screen panel or a touch sensor film.

Referring to FIG. 4, the touch sensor may include a sensing electrode 210, a trace 220, and a pad 230 formed on a substrate 205.

The touch sensor may include a sensing area (A) and a peripheral area (B). The sensing electrode 210 is formed on the substrate 200 of the sensing area A and the trace 220 and the pad 230 may be formed on the substrate 200 of the peripheral area B.

The sensing electrode 210 may include a first sensing electrode 210a and a second sensing electrode 210b arranged in a first direction and a second direction that are parallel to the upper surface of the substrate 200 and cross each other at right angles, . ≪ / RTI >

The first sensing electrode 210a extends in the first direction and a plurality of first sensing electrodes 210a may be formed along the second direction. The second sensing electrode 210b may extend in the second direction and may include a plurality of second sensing electrodes 210b along the first direction.

The first and second sensing electrodes 210a and 210b may include, for example, polygonal unit patterns and may include a connection portion or a bridge electrode that connects neighboring unit patterns. The inside of the unit pattern may include a conductive pattern patterned in a mesh type.

A trace 220 may be branched from each of the sensing electrodes 210a and 210b and a distal end of the trace 220 may be connected to the pad 230. [ The touch sensor may be connected to an external circuit such as a flexible printed circuit board (FPCB) through a pad 230.

As described above, the neutral surface NP4a as shown in FIG. 2 is formed inside the touch sensor, so that cutting, cracking, etc. of the sensing electrode 210, the bridge electrode, and the trace 220 can be prevented during bending .

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to be illustrative of the invention and are not intended to limit the scope of the claims. It will be apparent to those skilled in the art that such variations and modifications are within the scope of the appended claims.

Examples and Comparative Examples

Example 1

A pixel electrode, an organic light emitting layer, an opposite electrode, and an encapsulation layer were sequentially formed on a substrate (polyimide polymer, thickness 30 μm) having a width of 10 cm and a length of 10 cm, respectively, 120 mu m). An acrylic-based OCA composition was applied onto the display panel sample to form a 25 mu m-thick layer. A touch sensor layer (forming an ITO electrode pattern layer on a triacetyl cellulose film) and a polarizing plate (a triacetylcellulose (TAC) protective film were bonded to both sides of a polyvinyl alcohol polarizer film on the second point- Was adhered to one surface of a protective film, manufactured by Dongwoo Fine-Chem) to form a functional module (total thickness: 100 m) to form a display module layer.

Then, a first point-of-adhesion layer of the same material and thickness (25 탆) as the second point-application layer and a window substrate (polyimide-based, thickness: 70 탆, manufactured by Sumitomo) were laminated on the polarizing plate, A flexible display device (total thickness: 340 mu m) was produced.

Examples 2 to 6, Comparative Examples 1 and 2

The flexible display devices of Examples 2 to 6 and Comparative Examples 1 and 2 were fabricated in the same manner as in Example 1 except that the thicknesses of the first and second adhesive layers were changed and the storage elastic modulus was changed by controlling the degree of curing of the adhesive layer. Devices. The thickness and the storage elastic modulus of each of the pressure-sensitive adhesive layers included in Examples and Comparative Examples are as shown in Table 1 below.

The elastic modulus measurements of Examples and Comparative Examples

The storage elastic modulus of the pressure-sensitive adhesive layer was measured using a viscoelasticity measuring device (MCR-301, Anton Paar). Specifically, the size of the point-adhesive layer sample was measured with a length of 30 mm and a width of 30 mm, and the sample was bonded to a glass plate and bonded to the measuring tip under the conditions of a frequency of 1.0 Hz and a strain of 2%.

The tensile elastic modulus of the window substrate and the display module layer was measured by tensile test at a tensile speed of 4 mm / min using a universal testing machine (Autograph AG-I, Shimizu Co., Ltd.) with a sample size of 100 mm long × 40 mm wide Respectively.

division The point- window Display module layer Bending adhesion modulus
(BAM)
(MPa) Storage modulus (25 ° C, MPa) thickness
(탆) Tensile modulus (25 DEG C, MPa) Tensile modulus (25 DEG C, MPa) Example 1 0.03 0.005 25 4,000 3,500 Example 2 0.1 0.03 50 4,000 3,500 Example 3 0.2 0.03 25 4,000 3,500 Example 4 10 4 100 4,000 3,500 Example 5 20 5 50 4,000 3,500 Example 6 0.2 0.03 25 7,500 3,500 Comparative Example 1 0.01 0.005 100 4,000 3,500 Comparative Example 2 31 4.5 25 4,000 3,500 Comparative Example 3 0.2 0.03 25 3,500 3,500

Experimental Example

1.Real workability evaluation

In the flexible display devices of the embodiments and the comparative example, the end portion formed by inserting the blade at the interface between the window substrate and the first point-contact layer was attached to a jig of an universal testing machine (Autograph AG-I, Shimizu Corporation) min to measure the residual adhesive surface area of the adhesive layer on the release surface, and the reworkability was evaluated according to the following formula (2).

&Quot; (2) "

(%) = Residual area of the viscous material of the viscous adhesive layer / total adhesion area x 100

2. Crack evaluation

Flexural evaluation was performed on the flexible display devices of Examples and Comparative Examples using a folding tester (DLDMLH-FS, YUASA). The size of the bonded sample was 100 mm x 10 mm, and the sample was bonded to the tester machine in reverse order so that one sample was subjected to bending tensile stress and the other sample was subjected to bending compressive stress. After the sample was mounted, the flexural evaluation was carried out at a speed of 30 minutes / min at 1R.

After bending, the flexion of each sample was observed with an optical microscope (ECLIPSE LV100ND, NIKON) to determine the number of cracks. The evaluation results are shown together in Table 2 below.

division Re-workability (%) crack number Example 1 15 10 Example 2 12 5 Example 3 8 none Example 4 10 none Example 5 12 5 Example 6 18 13 Comparative Example 1 42 30 Comparative Example 2 55 33 Comparative Example 3 60 15

Referring to Table 2, it can be seen that a tensile elastic modulus at 25 ° C of any of the window or display module layers satisfies 4,000 MPa or more, and the BAM of the pressure-sensitive adhesive layer satisfies 0.03 to 20 MPa. It can be confirmed that the display device is prevented from residue during rework and has excellent bending property.

Examples 1, 2, 5, and 6, in which the BAM of the point-adhesive layer slightly deviates from the preferred range, or the tensile modulus of the window is 7,500 MPa, are somewhat increased as compared with Examples 3 and 4, Was found to be finer, but it was confirmed that it has remarkably superior performance to the comparative examples.

However, it can be seen that the comparative examples are not very good in reworkability and cracks remarkably than the embodiments, and thus are not suitable as a flexible display device.

10: display module layer 20: window
50: first point adhesive layer 70: second point adhesive layer
90: third point adhesive layer 100: display panel
105: panel substrate 110: active layer
115: gate insulating film 120: gate electrode
125: interlayer insulating film 132: source electrode
134: drain electrode 140: via insulating film
145: pixel electrode 150: pixel defining film
170: counter electrode 180: encapsulation layer
160: Display layer 200: Functional structure
200a: touch sensor 200b: polarizing layer
210: sensing electrode 220: trace
230: Pad

Claims (14)

A display module layer;
A window disposed on the display module layer; And
And a first point-of-adhesive layer disposed between the display module layer and the window,
Wherein the first adhesive layer has a Bending Adhesive Modulus (BAM) of 0.03 to 20 MPa, calculated according to the following formula (1)
Wherein a tensile modulus at 25 ° C of the window and the display module layer is 4,000 MPa or more.
[Equation 1]
Bending Adhesion Modulus (BAM) = storage elastic modulus at 25 占 폚 of the pressure-sensitive adhesive layer /
(In the formula (1), the thickness ratio of the pressure-sensitive adhesive layer is a ratio of the thickness of the pressure-sensitive adhesive layer to the total thickness of the flexible display device).
The flexible display device according to claim 1, wherein a neutral plane is formed at an interface between any one of the windows and the display module layer having a tensile elastic modulus at 25 ° C of 4,000 MPa or more and the first adhesive layer.
The flexible display device according to claim 1, wherein the thickness of the first adhesive layer is 10 to 100 mu m.
[2] The flexible display device of claim 1, wherein the first adhesive layer is formed of an acrylic pressure sensitive adhesive (PSA) composition or an optically clear adhesive (OCA) composition.
The flexible display device of claim 1, wherein the tensile modulus at 25 ° C of the window and the display module layer is at least 4,000 MPa and the tensile modulus at 25 ° C is less than 4,000 MPa.
The flexible display device of claim 1, wherein the window has a tensile modulus at 25 ° C of at least 4,000 MPa and a tensile modulus at 25 ° C of the display module layer is less than 4,000 MPa.
The display device according to claim 1, wherein when the flexible display device is bent,
Wherein a neutral plane is formed in each of the display module layer and the window.
The flexible display device of claim 1, wherein the first point-of-use adhesive layer is in direct contact with the display module layer and the window.
The display module of claim 1, wherein the display module layer comprises: a display panel;
A functional structure disposed on the display panel; And
And a second adhesive layer disposed between the display panel and the functional structure.
The flexible display device of claim 9, wherein the display panel comprises an organic light emitting diode (OLED) panel or a liquid crystal display (LCD) panel.
The flexible display device of claim 9, wherein the functional structure comprises at least one of a touch sensor or a polarizing layer.
[12] The method of claim 9, wherein the second adhesive layer has a flexural modulus of 0.03 to 20 MPa,
Wherein the tensile modulus at 25 ° C of the functional structure and the display panel is 2,000 MPa or more.
The flexible display device according to claim 12, wherein the neutral surface is formed at the interface between any one of the functional structure and the display panel having the tensile elastic modulus at 25 ° C of 4,000 MPa or more and the second point-adhesive layer.
10. The display device according to claim 9, wherein when the flexible display device is bent,
And a neutral plane is formed inside the functional structure and the display panel, respectively.

Images