KR20160002592A - Display device - Google Patents

Abstract

The present invention discloses a display device. The display device includes: a display panel including a first substrate and a second substrate; and a cover substrate disposed on the display panel and including a carbonate compound. The cover substrate has superior flexibility, surface hardness, and durability even in high temperature and high humidity environments.

Description

Display device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly, to a display device having improved flexibility and improved touch sensitivity.

[0002] In recent years, as the information age has come to a full-fledged information age, a display field for visually expressing electrical information signals has been rapidly developed. In response to this, various flat panel display devices having excellent performance of thinning, light- (Flat Display Device) has been developed to replace CRT (Cathode Ray Tube).

Specific examples of such a display device include a liquid crystal display device (LCD), an organic light emitting display (OLED), an electrophoretic display (EPD) A plasma display panel (PDP), a field emission display (FED), an electroluminescence display device (ELD), and an electro-wetting display (EWD) .

2. Description of the Related Art In recent years, display devices have been actively developed, so that diversity is required different from existing designs, display devices capable of enhancing aesthetic functions, and capable of providing various functions in use are being discussed. A flexible display device has been developed using a flexible substrate such as a plastic or the like, and various design modifications are possible compared with the conventional flat display device.

A cover substrate can be applied on the screen of such a display device. The cover substrate needs to be formed to have high hardness and impact resistance in order to protect the display device. Conventionally, such a cover substrate has been generally made of tempered glass. However, in the case of tempered glass, it is difficult to apply it to a flexible display device because of poor formability. Recently, studies on a cover substrate made of a plastic material having excellent moldability have been actively attempted. However, in the case of the plastic material, the surface hardness is lower than that of the glass material, so that the scratch resistance is poor, and the material is easily deformed in a high temperature and high humidity environment, thereby lowering the reliability of the product.

In recent years, a touch panel has been applied in which an input device such as a finger or a stylus pen is brought into contact with an image displayed on a display device. The touch panel is typically divided into a resistive touch panel and a capacitive touch panel.

The resistance film type touch panel senses that the resistance changes according to the connection between the electrodes when the pressure is applied to the input device, and the position is detected. A capacitance type touch panel senses a change in electrostatic capacitance between electrodes when a finger touches them, thereby detecting the position. Considering the convenience of the manufacturing method and the sensing power, recently, in a small model, the electrostatic capacity method has attracted attention. In order to smoothly drive the touch function in the display device to which the touch panel is applied, it is preferable that the cover substrate having a thick thickness has a high dielectric constant. However, in the case of a plastic material, since it has a lower dielectric constant than most tempered glass, when a cover substrate is formed of a plastic material, there is a problem that touch sensitivity is lowered.

Accordingly, there is a need to develop a cover substrate having excellent surface hardness, excellent reliability in a high temperature and high humidity environment, and excellent moldability without lowering touch sensitivity.

An object of the present invention is to provide a display device including a cover substrate having excellent flexibility and surface hardness, and having excellent durability even in a high temperature and high humidity environment.

It is another object of the present invention to provide a display device having improved touch sensitivity including a cover substrate having an improved dielectric constant.

According to an aspect of the present invention, there is provided a display device including: a display panel including a first substrate and a second substrate; And a cover substrate disposed on the display panel and containing a carbonate compound.

The display device according to the present invention can realize various designs including a cover substrate having excellent flexibility, surface hardness and durability in a high temperature and high humidity environment, and is excellent in external shock, excellent in reliability in high temperature and high humidity environment .

Further, the display device according to the present invention includes a cover substrate having an improved dielectric constant, so that deterioration of touch sensitivity can be minimized.

1 is a view showing a display device according to an embodiment of the present invention.
2 and 3 are views for explaining a display panel of a display device according to an embodiment of the present invention.
4 and 5 are views for explaining a touch panel of a display device according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

A display device according to an embodiment of the present invention will now be described with reference to FIGS. 1 to 5. FIG. FIG. 1 is a view illustrating a display device according to an embodiment of the present invention. FIG. 2 and FIG. 3 are views for explaining a display panel of a display device according to an embodiment of the present invention. 4 and 5 are views for explaining a touch panel of a display device according to an embodiment of the present invention.

Referring to FIG. 1, a display device 100 according to an embodiment of the present invention may include a display panel 300 and a cover substrate 200. In addition, the display device 100 according to the embodiment of the present invention may further include a touch panel 400.

First, the cover substrate 200 will be described.

The cover substrate 200 may be disposed on the uppermost layer of the display device 100 to protect the display device 100. That is, the cover substrate 200 may protect the display panel 300 or the touch panel 400 disposed under the cover substrate 200. The thickness of the cover substrate 200 may be 700 [mu] m to 1000 [mu] m.

The cover substrate 200 may include polymethylmethacrylate (PMMA) and a carbonate compound. The carbonate compound may include a compound represented by the following formula (1).

[Chemical Formula 1]

In Formula 1, R ₁ to R ₄ are each independently hydrogen or alkyl having 1 to 10 carbon atoms. Preferably, R ₂ to R ₄ may be hydrogen, and more preferably, R ₁ to R ₄ may be hydrogen.

Meanwhile, in the present invention, the carbonate compound may be contained in an amount of 5 wt% to 30 wt% of the cover substrate 200. When the amount of the carbonate compound is less than 5 wt%, the dielectric constant, hardness, and flexibility may be relatively small. In addition, when the carbonate compound is contained in an amount of more than 30 wt%, the mechanical properties of the cover substrate 200 may change and the stability may be deteriorated.

The cover substrate 200 of the present invention as described above has an excellent surface hardness as compared with a conventionally known cover substrate made of a plastic material. For example, the cover substrate may have a pencil hardness of 8H or more, preferably 8H to 12H, more preferably 9H to 12H. Therefore, the display device to which the cover substrate 200 of the present invention is applied is excellent in scratch resistance and abrasion resistance.

In addition, the cover substrate 200 has excellent durability in a high temperature and high humidity environment. For example, the cover substrate 200 may have an expansion ratio of 0.1% or less, preferably 0.05% or less, more preferably 0.02% or less, after 96 hours of storage at 70 ° C and 90% relative humidity.

In addition, the cover substrate 200 is excellent in flexibility and can be formed into various designs such as bending, folding, and rolling, and thus can be applied to a flexible display device. For example, the cover substrate 200 may have a bending degree of 45 mm or less, preferably 40 mm or less, more preferably 20 mm to 40 mm. At this time, the curvature was measured as the radius R of the drum immediately before the cover substrate was damaged after attaching the cover substrate to the semi-cylindrical drum having various curvature radii.

Further, the cover substrate 200 has a high dielectric constant. Preferably, the cover substrate 200 may have a dielectric constant of 4.0 or more. More preferably, the cover substrate 200 may have a dielectric constant of 4.0 to 8.0.

When the touch panel 400 is formed in a capacitive manner, the touch performance is affected by the dielectric constant of the material. Particularly, the dielectric constant of the cover substrate 200, which is formed on the uppermost layer and is disposed adjacent to an input device such as a finger or a stylus pen and has the thickest thickness among a plurality of substrates included in the display device, Lt; / RTI > Accordingly, when the cover substrate 200 of the present invention having improved dielectric constant is used, the display device 100 having enhanced touch sensitivity and touch performance can be realized.

Next, the display panel 300 will be described.

The display panel 300 may be a liquid crystal display panel or an organic light emitting display panel. Referring to FIG. 2, a case where the display panel 300 is a liquid crystal display panel will be described as follows.

Referring to FIG. 2, the display panel 300 is a liquid crystal display panel. The liquid crystal display panel 300 is formed by bonding a first substrate 301 and a second substrate 302 with a liquid crystal layer 380 therebetween. Although not shown in the drawing, a backlight unit may be disposed under the liquid crystal display panel 300. Further, although not shown in the figure, a polarizer may be attached to the outer surfaces of the first and second substrates 301 and 302 to selectively transmit only specific polarized light.

The liquid crystal display panel 300 may be divided into a display area and a non-display area. On one surface of the first substrate 301 in the display area, a gate line and a data line cross each other with a gate insulating layer 352 interposed therebetween to define a pixel region. A thin film transistor (TFT) is provided in the pixel region and is connected in a one-to-one correspondence via a pixel electrode 357 provided in each pixel region and a contact hole formed in the insulating layer 356. That is, the first substrate 301 may be a thin film transistor substrate or an array substrate.

The thin film transistor TFT includes a gate electrode 351, a gate insulating film 352, a semiconductor layer 353, a source electrode 354, and a drain electrode 355. Although the bottom gate structure in which the gate electrode 351 of the thin film transistor is disposed under the semiconductor layer 353 is shown in the drawing, the gate electrode 351 is formed on the semiconductor layer 353 Or may be formed with a top gate structure in which a gate electrode is disposed. In addition, the configuration and the like of the thin film transistor can be variously modified and modified within a range not departing from the technical idea of the present invention.

A black matrix 371 (not shown) is formed on one surface of the second substrate 302 of the liquid crystal display panel 300 to cover a non-display region such as a thin film transistor Is formed. In addition, R (red), G (green), and B (blue) color filter layers 372 that are sequentially and repeatedly arranged in correspondence to the respective pixel regions in these lattices and a transparent common electrode 373 covering all of them are included .

A first alignment layer 358 and a second alignment layer 374 are interposed between the liquid crystal layer 380 and the pixel electrode 357 and between the liquid crystal layer 380 and the common electrode 373. The first alignment layer 358 and the second alignment layer 374 can align the initial alignment state of the liquid crystal molecules and the alignment direction uniformly.

However, the drawings illustrate the liquid crystal display panel according to the present invention in a simplified manner, but the present invention is not limited thereto. For example, although the thin film transistor is represented by a single thin film transistor in the drawing, the thin film transistor may be composed of one or more thin film transistor combinations depending on the characteristics of operation.

In addition, a method of controlling the arrangement of liquid crystal molecules can be variously applied to an IPS (In Plane Switching) mode or an FFS (Fringe Field Switching) mode in addition to a TN (Twisted Nematic) mode and a VA (Vertical Alignment) mode. Although the pixel electrode 357 is formed on the first substrate 301 and the common electrode 373 is formed on the second substrate 302 in the drawing, the pixel electrode 357 and the common electrode 373 ) Can also be changed and modified. The pixel electrode 357 and the common electrode 373 may be formed on the first substrate 301 in an IPS (In Plane Switching) mode or an FFS (Fringe Field Switching) mode.

The liquid crystal display panel 300 may include a thin film transistor, a color filter layer and a black matrix formed on a first substrate 301 and a second substrate 302 with a liquid crystal layer interposed therebetween. Or a liquid crystal display panel having a color filter on transistor (COT) structure. That is, a thin film transistor may be formed on the first substrate 301, a protective film may be formed on the thin film transistor, and a color filter layer may be formed on the protective film. In addition, a pixel electrode is formed on the first substrate 301 to be in contact with the thin film transistor. At this time, in order to improve the aperture ratio and simplify the mask process, the black matrix may be omitted, and the common electrode may be formed to serve also as the black matrix.

In other words, the liquid crystal display panel 300 is not limited to the representation of the drawings, and the configuration and the like of the thin film transistor can be variously modified and modified as long as the technical idea of the present invention is not deviated.

Next, referring to FIG. 3, the case where the display panel 300 is an organic light emitting display panel will be described.

Referring to FIG. 3, the display panel 300 is an organic light emitting display panel. The organic light emitting display panel 300 includes a first substrate 301 on which a thin film transistor TFT and an organic light emitting diode OL electrically connected to the thin film transistor TFT are formed, And a second substrate 302 for carrying out the present invention. An encapsulation layer 324 may be formed between the first substrate 301 and the second substrate 302. Although the encapsulation layer 324 is shown as a single layer in the drawing, the encapsulation layer 324 may be composed of a plurality of layers such as a protective layer and an adhesive layer.

The organic light emitting display panel 300 may be divided into a display area and a non-display area. A thin film transistor (TFT) is formed on one surface of the first substrate 301 in a display region of the organic light emitting display panel 300. The thin film transistor (TFT) includes a semiconductor layer 311, a gate electrode 313, a source electrode 315, and a drain electrode 316.

In detail, a semiconductor layer 311 including a source region 311a, a channel region 311b, and a drain region 311c is formed on the first substrate 301. [ A gate insulating film 312 is formed on the semiconductor layer 311 and a gate wiring 313 and a gate electrode 313 branched from the gate wiring are formed on the gate insulating film 312. An interlayer insulating film 314 is formed on the gate wiring and the gate electrode 313.

A source electrode 315 branched from the data line, and a drain electrode 316 spaced apart from the source electrode 315 by a predetermined distance, the data line crossing the gate line with the interlayer insulating film 314 therebetween, Is formed. The source electrode 315 and the drain electrode 316 are electrically connected to each other through an interlayer insulating layer 314 formed on the gate electrode 313 and a contact hole formed through the gate insulating layer 312, And is in contact with the source region 311a and the drain region 311c.

A protective film 317 is formed on the source electrode 315 and the drain electrode 316 and a contact hole exposing the drain electrode 316 is formed on the protective film 317. The exposed drain electrode 316 is electrically connected to the connection electrode 318 formed on the passivation layer 317. A planarization layer 319 is formed on the entire surface of the first substrate 301 including the thin film transistor TFT and a contact hole exposing the connection electrode 318 is formed on the planarization layer 319.

The organic light emitting diode OL is electrically connected to the TFT through a contact hole formed in the planarization layer 319. [ The organic light emitting device OL includes a lower electrode 320, an organic light emitting layer 322, and an upper electrode 323.

More specifically, the lower electrode 320 of the organic light emitting diode OL is formed on the exposed connection electrode 318. Although the lower electrode 320 of the organic light emitting diode OL and the drain electrode 316 of the thin film transistor TFT are shown as being connected through the connection electrode 318 in the drawing, the connection electrode 318 is omitted, The lower electrode 320 of the light emitting device OL and the drain electrode 116 of the thin film transistor TFT may be directly in contact with each other through the planarization film 319 having the contact holes.

A bank pattern 321 is formed on the lower electrode 320 to expose the lower electrode 320 in units of pixel regions. An organic light emitting layer 322 is formed on the exposed lower electrode 320. The organic light emitting layer 322 may be formed of a single layer made of a light emitting material or may include a hole injection layer, a hole transporting layer, an emitting material layer, and an electron transporting layer an electron transporting layer, and an electron injection layer.

An upper electrode 323 is formed on the organic light emitting layer 322. When the lower electrode 320 is an anode, the upper electrode 323 is a cathode, and when the lower electrode 320 is a cathode, the upper electrode is an anode .

A sealing portion is formed on the first substrate 301 on which the thin film transistor TFT and the organic light emitting diode OL are formed. For example, on the upper electrode 323, a sealing layer 324 for protecting the display elements is formed. The sealing layer 324 may be formed of a plurality of layers and may be bonded to the second substrate 302. The second substrate 302 may be an encapsulation substrate for encapsulation. However, the sealing part disposed on the first substrate 301 is not limited to the sealing layer 324 and the second substrate 302, and may be formed by various sealing methods known in the art to prevent the inflow of oxygen or moisture. Additional applications can be applied.

Further, the structure of the organic light emitting display device according to the present invention is not limited to the drawings, and various changes and modifications can be made without departing from the technical idea of the present invention.

Next, the touch panel 400 will be described.

The touch panel 400 may be an add-on type touch panel 400. In addition, the touch panel 400 may be an integrated type touch panel 400.

When the touch panel 400 is an external touch panel 400, the touch panel 400 may have a separate structure from the display panel 300. A transparent adhesive layer (not shown) may be formed between the touch panel 400 and the display panel 300.

The touch panel 400 may be formed separately from the cover substrate 200 or may be integrally formed with the cover substrate 200. A transparent adhesive layer (not shown) may be formed between the touch panel 400 and the cover substrate 200 when the touch panel 400 is formed as a separate structure from the cover substrate 200 . When the touch panel 400 is formed integrally with the cover substrate 200, sensing electrodes and the like may be formed on the back surface of the cover substrate 200. That is, a separate adhesive layer is not required between the touch panel 400 and the cover substrate 200.

When the touch panel 400 is an embedded touch panel 400, the touch panel 400 may be formed integrally with the display panel 300. That is, a separate adhesive layer is not required between the touch panel 400 and the display panel 300. The touch panel 400 may be an on-cell type or an in-cell type.

When the touch panel 400 is an on-cell type, a sensing electrode may be formed on the upper surface of the display panel 300. In detail, a sensing electrode or the like may be formed directly on the substrate disposed on the display panel 300. Like the external touch panel 400, the touch panel 400 may be formed separately from the cover substrate 200, or may be integrally formed with the cover substrate 200.

When the touch panel 400 is an in-cell type, a sensing electrode may be formed between the first substrate and the second substrate of the display panel 300. That is, a sensing electrode or the like may be formed together when the display panel 300 is formed. At this time, the cover substrate 200 is formed separately from the touch panel 400. Further, a transparent adhesive layer may be formed between the cover substrate 200 and the display panel 300.

Referring to FIGS. 4 and 5, the touch panel 400 will be described in more detail as follows. 4 and 5 show an example in which the external touch panel is formed separately from the cover substrate 200. The configuration of the touch panel 400 is not limited to the drawings. The touch panel 400 may be applied to both the external and internal touch panels as described above.

4 and 5, the touch panel 400 may be divided into a display area AA through which light is transmitted and a non-display area IA through which light is not transmitted. The non-display area IA is a concept opposite to the display area AA and is activated even when the user touches the display area AA. And the touch command input is not performed.

Referring to FIG. 4, the touch panel 400 may include a sensing electrode 421 and a wiring 422 on one surface of a first touch substrate 401. The first touch substrate 401 may include, but is not limited to, tempered glass, semi-tempered glass, soda lime glass, reinforced plastic or soft plastic.

The sensing electrode 421 may be disposed on the display area AA and the wiring 422 may be disposed on the non-display area IA. Although not shown in the drawing, a print layer may be further formed in the non-display area IA of the first touch substrate 401. [ In addition, a wiring 422 may be formed on the print layer.

The sensing electrode 421 may include a conductive material. For example, the sensing electrode 421 may be selected from the group consisting of a transparent conductive material, a metal, a nanowire, a photosensitive nanowire film, a carbon nanotube (CNT), a graphene, a conductive polymer, And may include any one of them.

The sensing electrode 421 may include a first sensing electrode 411 and a second sensing electrode 412. The first sensing electrode 411 and the second sensing electrode 412 may include the same material or may include different materials. The first sensing electrode 411 and the second sensing electrode 412 may be disposed on the same surface of the first touch substrate 401.

When the first sensing electrode 411 and the second sensing electrode 412 are disposed on the same surface of the first touch substrate 401, the first sensing electrode 411 and the second sensing electrode 412 Should not be in contact with each other. To this end, an insulating layer and a bridge electrode may be further disposed.

In detail, one of the first sensing electrode 411 and the second sensing electrode 412 is disposed below the insulating layer, and the other is disposed at both ends of the bridge electrode formed on the insulating layer Can be connected and electrically connected. Accordingly, the first sensing electrode 411 and the second sensing electrode 412 can be electrically connected to each other without being short-circuited by the bridge electrode and the insulating layer.

The first sensing electrode 411 and the second sensing electrode 412 may be disposed on the display area AA to sense a touch. in details. The first sensing electrode 411 may extend in one direction on the display area AA and the second sensing electrode 412 may extend in a direction different from the first direction.

The wiring 420 may include a first wiring 421 and a second wiring 422. In detail, the wiring 420 may include the first wiring 421 connected to the first sensing electrode 411 and the second wiring 422 connected to the second sensing electrode 412. have.

The first wiring 421 and the second wiring 422 may be connected to a printed circuit board (not shown). More specifically, the first wiring 421 and the second wiring 422 are mounted on a driving chip (not shown) through a touch signal detected from the first sensing electrode 411 and the second sensing electrode 412, To the printed circuit board (not shown) to perform a touch operation. The printed circuit board (not shown) may be, for example, a flexible printed circuit board (FPCB).

The first wiring 421 and the second wiring 422 may include a conductive material. For example, the first wiring 421 and the second wiring 422 may include a metal material such as silver (Ag) or copper (Cu).

Although not shown in the drawing, a protective layer (not shown) may be further formed on the wiring 420. The protection layer (not shown) may protect the wiring 420. Specifically, the protective layer (not shown) can prevent the reliability of the wiring 420 from being deteriorated due to oxidation of the wiring 420 due to exposure to oxygen, or moisture penetration.

Referring to FIG. 5, the touch panel 400 may include a first touch substrate 402 and a second touch substrate 403. The first touch substrate 402 and the second touch substrate 403 may include, but are not limited to, tempered glass, semi-tempered glass, soda lime glass, reinforced plastic or soft plastic. The first touch substrate 402 and the second touch substrate 403 may be bonded using a transparent adhesive such as an optical transparent adhesive (OCA).

A first sensing electrode 411 may be disposed on the display area AA of the first touch substrate 402. In addition, a first wiring 421 connected to the first sensing electrode 411 may be disposed in the non-display area IA of the first touch substrate 402.

A second sensing electrode 412 may be disposed on the display area AA of the second touch substrate 403. [ In addition, a second wiring 422 connected to the second sensing electrode 412 may be disposed in the non-display area IA of the second touch substrate 403. The first wiring 421 and the second wiring 422 may be electrically connected to a printed circuit board (not shown), respectively.

However, the touch panel 400 is not limited to the drawings and the above description, and may be an input device capable of inputting in a manner that the touch panel 400 is in contact with the front face of the display device using a finger, a stylus pen, or the like Do. That is, the touch panel 400 can be applied without limitation as long as it is generally used.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are intended to illustrate the present invention and are not intended to limit the present invention. That is, the embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed to be limited by the embodiments described below.

[Example 1]

A cover substrate having a thickness of 0.8 mm was prepared using a resin composition formed by mixing 90% by weight of polymethylmethacrylate (PMMA) and 10% by weight of ethylene carbonate.

[Example 2]

A cover substrate having a thickness of 0.8 mm was prepared using a resin composition formed by mixing 85% by weight of polymethylmethacrylate (PMMA) and 15% by weight of ethylene carbonate.

[Example 3]

A cover substrate having a thickness of 0.8 mm was prepared using a resin composition formed by mixing 80% by weight of polymethylmethacrylate (PMMA) and 20% by weight of ethylene carbonate.

[Comparative Example 1]

A cover substrate having a thickness of 0.8 mm was prepared using polymethylmethacrylate (PMMA) resin.

 [Comparative Example 2]

A cover substrate having a thickness of 0.8 mm was prepared using a copolymer resin of polymethylmethacrylate and styrene (polymethylmethacrylate: styrene = 60% by weight: 40% by weight).

[Comparative Example 3]

A polymethylmethacrylate resin and a polycarbonate resin were co-extruded to prepare a cover substrate composed of a polymethylmethacrylate layer having a thickness of 0.1 mm and a polycarbonate layer having a thickness of 0.7 mm.

[Comparative Example 4]

A cover substrate having a thickness of 0.8 mm was prepared using a resin composition formed by mixing 90% by weight of polymethylmethacrylate (PMMA) and 10% by weight of rubber (product name: cis-1220).

[Comparative Example 5]

A cover substrate having a thickness of 0.8 mm was prepared by using a resin composition formed by mixing 90% by weight of polymethylmethacrylate (PMMA) and 15% by weight of a rubber (product name: cis-1220).

[Comparative Example 6]

A cover substrate having a thickness of 0.8 mm was prepared by using a resin composition formed by mixing 90% by weight of polymethylmethacrylate (PMMA) and 10% by weight of zirconia (Zirconia, ZrO ₂ ).

[Comparative Example 7]

Aluminum-doped zinc oxide (AZO) was coated on the substrate having a polymethyl methacrylate (PMMA) content of 100 wt% prepared in Comparative Example 1 to a thickness of 0.5 μm to prepare a cover substrate.

 [Experimental Example]

The transmittance, haze, dielectric constant, surface hardness, heat distortion temperature, high temperature and high humidity expansion rate, bendability, and durability of the cover substrates prepared in Examples 1 to 3 and Comparative Examples 1 to 7 were measured as follows. The measurement results are shown in Table 1 below.

(1) transmittance, haze,

After cutting the cover substrate sample to a size of 10 mm x 10 mm, the entire transmission light, diffused light, and parallel light were measured using a Dis-haze meter (Model: TC-HIIIDPK / III, Tokyo Denshoku) Respectively.

(2) Permittivity

Using a Precision impedance analyzer (Model: E4980A, manufactured by Hitachi, Ltd.), the permittivity was measured at a frequency of 1 KHz to 1 MHz under a condition of 3 V applied. The sample used for the measurement was 100 mm ² ~ 900 mm ^2, and the upper and lower surfaces were coated with Pt having a thickness of 20 nm to 100 nm. In the measurement method, the probes are brought into contact with the upper and lower coating layers, voltages are applied, and the amount of charge is measured to calculate the dielectric constant

(3) Surface hardness

The end of the pencil was made flat with 400 cW of sand paper, and then the pencil was adjusted to 45 degrees on the surface of the sample. When a scratch shape occurs on the surface of a sample, a pencil having a hardness one level lower than the pencil used for measurement is taken as the surface hardness value.

(4) Heat deformation temperature

The thermal deformation temperature was measured by a 3-point bending method under a temperature elevation condition of 5 ° C / min and a load of 10 g using Dynamic Mechanical Analysis (DMA).

(5) High temperature, high humidity expansion rate

The cover substrate was allowed to stand at 70 DEG C and 90% relative humidity for 96 hours, and the expansion ratio was measured. The expansion ratio was calculated by the following formula.

Expansion ratio (%) = {(length of cover substrate after leaving - length of cover substrate before leaving) / (length of cover substrate before leaving)} x 100

(6) Bending property

After the cover substrate was cut into a size of 100 mm x 30 mm, the cover substrate was attached to a drum having various curvature radii, and then the radius R of the drum just before the cover substrate was broken was evaluated for bending property at the curved line.

(7) Durability

22g SUS ball was dropped to measure the height at which breakage occurred.

Transmittance
(%) permittivity
(竜) surface
Hardness Thermal deformation
Temperature
(° C) High temperature and high expansion rate
(%) Bendability
(mm) durability
(cm) Hayes Example 1 92 4.2 9H 105 0.01 45 20 Less than 1.0 Example 2 92 4.5 9H 95 0.01 40 25 Less than 1.0 Example 3 92 4.8 9H 75 0.01 40 25 Less than 1.0 Comparative Example 1 92 3.0 9H 107 0.08 45 20 Less than 1.0 Comparative Example 2 92 3.0 3H 90 0.40 40 20 Less than 1.0 Comparative Example 3 91 2.9 4H 107 0.01 45 25 Less than 1.0 Comparative Example 4 91 2.8 7H 95 0.12 45 25 Less than 1.0 Comparative Example 5 91 2.8 7H 87 0.12 45 25 Less than 1.0 Comparative Example 6 87 4.2 9H 110 0.04 50 20 3.4 Comparative Example 7 92 3.0 3H 107 0.08 45 15 Less than 1.0

Referring to Table 1, it can be seen that the cover substrates of Examples 1 to 3 and Comparative Examples 1 to 5 and 7 are transparent with a transmittance of 90% or more and a haze of less than 1. On the other hand, in Comparative Example 6, the transmittance is 90% or less and the haze is as high as 3.4, which is not suitable for a display device.

In addition, referring to Table 1, it can be seen that the cover substrates of Examples 1 to 3 have a high dielectric constant of 4.0 or more, which is advantageous for realizing touch sensitivity and touch performance as compared with the cover substrates of Comparative Examples 1 to 4 and 7 .

Referring to Table 1, it can be seen that the cover substrates of Examples 1 to 3 have a surface hardness of about 9H and a high hardness. On the other hand, in the case of Comparative Examples 2 to 5 and 7, the surface hardness is low and it is not suitable as a cover substrate.

Referring to Table 1, it was confirmed that the cover substrates of Examples 1 to 3 had a thermal deformation temperature exceeding 70 ° C. Generally, the cover substrate has a print drying temperature of about 70 ° C. Therefore, in order to ensure processability, the heat distortion temperature should be 70 ° C or higher.

With reference to Table 1, the cover substrates of Examples 1 to 3 had very low dimensional change ratios (expansion ratios) of about 0.01% in a high temperature and high humidity environment, while Comparative Examples 1 to 2 and 4 to 7 corresponded to Examples 1 to 3 It is found that the dimensional change rate is higher than that of the conventional method.

In addition, referring to Table 1, it can be seen that the cover substrates of Examples 1 to 3 are excellent in moldability with a bending degree of 45 mm or less, whereas the flexible substrate of Comparative Example 6 has a low bending degree.

The features, structures, effects and the like described in the foregoing embodiments are included in at least one embodiment of the present invention and are not necessarily limited to one embodiment. Further, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified in other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the present invention. It can be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiments may be modified and implemented. It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.

100: display device
200: Cover substrate
300: Display panel
400: touch panel

Claims (16)

A display panel including a first substrate and a second substrate; And
And a cover substrate disposed on the display panel and containing a carbonate compound.
The method according to claim 1,
Wherein the carbonate compound comprises a compound represented by the following Formula 1:
[Chemical Formula 1]

In Formula 1, R ₁ to R ₄ are each independently hydrogen or alkyl having 1 to 10 carbon atoms.
3. The method of claim 2,
And R < ₂ > to R < ₄ > are hydrogen.
The method of claim 3,
Wherein R < _{1 >} is hydrogen.
The method according to claim 1,
And the carbonate compound is contained in an amount of 5 wt% to 30 wt% of the cover substrate.
The method according to claim 1,
And the dielectric constant of the cover substrate is 4.0 to 8.0.
The method according to claim 1,
Wherein the cover substrate has a surface hardness of 8H or more.
The method according to claim 1,
Wherein the cover substrate has an expansion ratio of not more than 0.1% measured after being left at 70 DEG C and a relative humidity of 90% for 96 hours.
The method according to claim 1,
Wherein the cover substrate has a curvature of 45 mm or less.
The method according to claim 1,
A touch panel is further disposed between the display panel and the cover substrate,
Wherein the touch panel includes a touch substrate having sensing electrodes formed thereon.
The method according to claim 1,
And a sensing electrode is formed on a rear surface of the cover substrate.
The method according to claim 1,
And a sensing electrode is formed on an upper surface of the display panel.
The method according to claim 1,
And a sensing electrode is formed between the first substrate and the second substrate of the display panel.
The method according to claim 1,
Wherein the display panel is a flexible display panel.
The method according to claim 1,
Wherein the display panel is an organic light emitting display panel.
The method according to claim 1,
Wherein the display panel is a liquid crystal display panel.

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