JP2016015138A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device with a cover substrate which is excellent in flexibility and surface hardness and has excellent durability under high-temperature high-humidity circumstances and which enhances touch sensitivity by an enhanced dielectric constant.SOLUTION: A display device 100 includes: a display panel 300 including a first substrate and a second substrate; and a cover substrate 200 disposed on the display panel 300 and containing a carbonate compound. The carbonate compound contains a compound represented by the formula in the figure, where Rto Rare each independently hydrogen or C1-C10 alkyl, and the dotted line represents a single bond or no bond.

Description

  The present invention relates to a display device, and more specifically to a display device with improved flexibility and touch sensitivity.

  Recently, with the progress of the full-fledged information era, the field of display devices that visually represent electrical information signals has been rapidly developing, and accordingly, thinning, lightening, and low power consumption. Various flat display devices (Flat Display Devices) with excellent performance have been developed, and are quickly replacing the existing cathode ray tube (CRT).

  Specific examples of such a display device include a liquid crystal display device (LCD), an organic light emitting display device (OLED), and an electrophoretic display device (EPD, Electric). Paper Display), Plasma Display Panel Device (PDP), Field Emission Display Device (FED), Electroluminescence Display Device (ELD), and Electro-Wetting Display Device (Electro-) Wetting Display (EWD).

  Recently, the development of display devices has been actively carried out, so that diversity that is different from existing designs is required, and display devices that can enhance aesthetic functions and provide multi-use functions. Is under discussion. A flexible display device using a flexible substrate such as plastic has been developed, and various design modifications are possible as compared with a conventional flat display device.

  A cover substrate is 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. When applied to a flexible display device, the cover substrate needs to be flexible. Conventionally, tempered glass has been mostly used as such a cover substrate. However, tempered glass has a problem that it is difficult to apply to a flexible display device because of poor moldability. Therefore, recently, research on a cover substrate made of a plastic material having excellent moldability has been actively attempted. However, the plastic material has a problem that the surface hardness is lower than that of the glass material, so that the scratch resistance is poor, and the product is easily deformed in a high-temperature and high-humidity environment and the reliability of the product is lowered.

  In recent years, a touch panel has been applied in which an image displayed on a display device is input by touching an input device such as a finger or a stylus pen. The touch panel can be typically classified into a resistive touch panel and a capacitive touch panel.

  When a pressure is applied to the input device, the resistance film type touch panel senses that the resistance changes due to the connection between the electrodes and detects the position. The capacitance type touch panel detects the position by sensing that the capacitance between the electrodes changes when a finger touches the touch panel. In consideration of the convenience of the manufacturing method and the sensing power, the electrostatic capacity method has recently attracted attention in small models. Thus, in a display device to which a touch panel is applied, it is preferable that the dielectric constant of the thick cover substrate is high so that the touch function can be smoothly driven. However, most plastic materials have a dielectric constant lower than that of tempered glass. Therefore, when the cover substrate is formed of a plastic material, there is a problem that touch sensitivity is lowered.

  Therefore, there is a need to develop a cover substrate that has excellent surface hardness, excellent reliability in a high-temperature and high-humidity environment, and excellent moldability without reducing touch sensitivity.

  An object of the present invention is to provide a display device including a cover substrate that has not only excellent flexibility and surface hardness but also excellent durability even in a high temperature and high humidity environment.

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

  A display device of the present invention for solving the problems of the prior art as described above 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. And the carbonate compound has the following formula:

(Wherein R _{1 to} R ₄ are each independently hydrogen or alkyl having 1 to 10 carbon atoms, and the dotted line means a single bond or a non-bond). To do.

  According to the present invention, it is possible to provide a display device including a cover substrate that has not only excellent flexibility and surface hardness but also excellent durability even in a high-temperature and high-humidity environment. In addition, according to the present invention, it is possible to provide a display device including a cover substrate having an improved dielectric constant and having improved touch sensitivity.

1 is a diagram illustrating a display device according to an embodiment of the present invention. 1 is a diagram for explaining a display panel of a display device according to an embodiment of the present invention. 1 is a diagram for explaining a display panel of a display device according to an embodiment of the present invention. It is drawing for demonstrating the touchscreen of the display apparatus which concerns on embodiment of this invention. It is drawing for demonstrating the touchscreen of the display apparatus which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the embodiments are exemplifications so that those skilled in the art can fully understand the idea of the present invention, and the present invention is not limited to these embodiments and is embodied in other forms. You can also. In the drawings, the size and thickness of the apparatus may be exaggerated for convenience. Note that the same reference numerals denote the same components throughout the specification.

  A display device according to an embodiment of the present invention will be described with reference to FIGS. FIG. 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 diagrams for explaining a touch panel of a display device according to an embodiment of the present invention.

  As shown in FIG. 1, the display device 100 according to the embodiment of the present invention may include a display panel 300 and a cover substrate 200. The cover substrate 200 is disposed above the display panel 300. 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 is disposed on the uppermost layer of the display device 100 and may serve to protect the display device 100. That is, the cover substrate 200 can protect the display panel 300 or the touch panel 400 disposed under the cover substrate 200. The cover substrate 200 has a thickness of 700 μm to 1000 μm.

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

However, in said formula, said R < ₁ > -R < ₄ > is respectively independently hydrogen or a C1-C10 alkyl, and a dotted line means a single bond or a non-bond. R _{2 to} R ₄ are preferably hydrogen, and R _{1 to} R ₄ are more preferably hydrogen.

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

  The cover substrate 200 of the present invention as described above has an excellent surface hardness as compared with a conventionally known plastic cover substrate. For example, the cover substrate may have a pencil hardness of 8H or more, preferably 8H to 12H, and 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 wear resistance.

  The cover substrate 200 has excellent durability in a high temperature and high humidity environment. For example, the cover substrate 200 has an expansion coefficient measured after being allowed to stand for 96 hours at a temperature of 70 ° C. and a relative humidity of 90%, and is 0.1% or less, preferably 0.05% or less, more preferably 0.00. 02% or less.

  Further, the cover substrate 200 is excellent in flexibility and can be formed into various designs such as bending, folding, rolling, and the like, and thus can be preferably applied to a flexible display device. it can. For example, the cover substrate 200 has a bending degree of 45 mm or less, preferably 40 mm or less, and more preferably 20 mm to 40 mm. Here, the bending degree is obtained by measuring a radius R value of the drum immediately after the cover substrate is damaged after the cover substrate is attached on a semi-cylindrical drum having various curvature radii.

  The cover substrate 200 has a high dielectric constant. The cover substrate 200 preferably has a dielectric constant of 4.0 or more. More preferably, the cover substrate 200 has 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. In particular, the dielectric constant of the cover substrate 200, which is the thickest among a number of substrates included in the display device, is formed as the uppermost layer and disposed adjacent to an input device such as a finger or a stylus pen, and acts as an important factor. To do. Therefore, when the cover substrate 200 of the present invention with an improved dielectric constant is used, the display device 100 with improved 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. Hereinafter, an example in which the display panel 300 is a liquid crystal display panel will be described with reference to FIG.

  As shown in FIG. 2, the display panel 300 is a liquid crystal display panel. The liquid crystal display panel 300 is formed by sandwiching a liquid crystal layer 380 between a first substrate 301 and a second substrate 302. Although not shown, a backlight unit is disposed below the liquid crystal display panel 300. Although not shown, a polarizing plate that selectively transmits only specific polarized light is further attached to the outer surfaces of the first substrate 301 and the second substrate 302.

  The liquid crystal display panel 300 is divided into a display area and a non-display area. In the display area, a gate line and a data line intersect each other vertically on one surface of the first substrate 301 with a gate insulating film 352 interposed therebetween to define a pixel area. A thin film transistor (TFT) is provided in the pixel region. The thin film transistor is connected to a pixel electrode 357 prepared in each pixel region through a contact hole formed in the protective 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. In the drawing, a bottom gate structure in which the gate electrode 351 of the thin film transistor is disposed under the semiconductor layer 353 is illustrated. However, a top gate in which the gate electrode 351 is disposed on the semiconductor layer 353 is illustrated. It can also be formed in a (top gate) structure. In addition, various changes and modifications can be made to the configuration of the thin film transistor without departing from the technical idea of the present invention.

  A grid-like black matrix 371 is formed on one surface of the second substrate 302 of the liquid crystal display panel 300 so as to cover a non-display region such as a thin film transistor (TFT) of the first substrate 301 and surround a pixel region. The In addition, R (red), G (green), and B (blue) color filter layers 372 that are sequentially and repeatedly arranged so as to correspond to the respective pixel regions within these lattices, and a transparent common electrode 373 that covers them all. Including.

  A first light distribution film 358 and a second light distribution film 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, respectively. The first light distribution layer 358 and the second light distribution layer 374 can uniformly align the initial alignment state and the alignment direction of the liquid crystal molecules.

  However, the drawings are not limited to the simplified liquid crystal display panel according to the present invention. For example, although a single thin film transistor is shown in the drawing, the thin film transistor may be composed of a combination of one or more thin film transistors depending on the characteristics of operation.

  In addition, a method for adjusting the alignment of liquid crystal molecules can be applied in various ways such as a TN (Twisted Nematic) mode, a VA (Vertical Alignment) mode, an IPS (In Plane Switching) mode, and an FFS (Fringe Field Switching) mode. Accordingly, the configuration in which the pixel electrode 357 is formed on the first substrate 301 and the common electrode 373 is formed on the second substrate 302 is illustrated in the drawing, but the configurations of the pixel electrode 357 and the common electrode 373 are also changed. Correction is possible. In an IPS (In Plane Switching) mode or an FFS (Fringe Field Switching) mode, the pixel electrode 357 and the common electrode 373 are formed on the first substrate 301.

  In the liquid crystal display panel 300, a thin film transistor, a color filter layer, and a black matrix are formed on a first substrate 301, and a second substrate 302 is bonded to the first substrate 301 with a liquid crystal layer interposed therebetween. It can also consist of a liquid crystal display panel with a color filter on transistor) 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 in contact with the thin film transistor is formed on the first substrate 301.

  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 on the first substrate 301 so as to function as a black matrix.

  That is, the liquid crystal display panel 300 is not limited to the illustrated one, and various changes and modifications can be made to the configuration of the thin film transistor without departing from the technical idea of the present invention.

  Hereinafter, a case where the display panel 300 is an organic light emitting display panel will be described with reference to FIG.

  As shown in 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 having a thin film transistor (TFT) and an organic light emitting device (OL) electrically connected to the thin film transistor (TFT), and the organic light emitting device (OL). ) To protect the second substrate 302. A seal layer 324 is formed between the first substrate 301 and the second substrate 302. Although the sealing layer 324 is illustrated as a single layer in the drawing, the sealing layer 324 may be composed of a number of layers such as a protective layer and an adhesive layer.

  The organic light emitting display panel 300 can 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 the display area 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.

  Specifically, 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 and a gate electrode 313 branched from the gate wiring are formed on the gate insulating film 312. An interlayer insulating layer 314 is formed on the gate line and gate electrode 313.

  A data line defining a pixel region intersecting the gate line with the interlayer insulating film 314 interposed therebetween, a source electrode 315 branched from the data line, and a drain electrode 316 spaced apart from the source electrode 315 by a certain distance. It is formed. At this time, each of the source electrode 315 and the drain electrode 316 is connected to the semiconductor layer through a contact hole formed through the interlayer insulating film 314 and the gate insulating film 312 formed on the gate electrode 313. 311 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 that exposes the drain electrode 316 is formed in the protective film 317. The exposed drain electrode 316 is electrically connected to a connection electrode 318 formed on the protective layer 317. A planarization film 319 is formed on the front surface of the first substrate 301 including the thin film transistor (TFT), and a contact hole in which the connection electrode 318 is exposed is formed in the planarization film 319.

  An organic light emitting device (OL) that is electrically connected to a thin film transistor (TFT) through a contact hole formed in the planarization layer 319 is formed. 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 device (OL) is formed on the exposed connection electrode 318. In the drawing, the lower electrode 320 of the organic light emitting device (OL) and the drain electrode 316 of the thin film transistor (TFT) are connected through the connection electrode 318, but the connection electrode 318 is omitted. The lower electrode 320 of the organic light emitting device (OL) and the drain electrode 116 of the thin film transistor (TFT) may be formed so as to be in direct contact with each other through the planarization film 319 in which the contact hole is formed. Accordingly, the protective layer 317 can be removed from the organic light emitting display panel 300.

  A bank pattern 321 is formed on the lower electrode 320 to expose the lower electrode 320 in pixel area units. An organic light emitting layer 322 is formed on the exposed lower electrode 320. The organic light emitting layer 322 may be a single layer made of a light emitting material, or a hole injection layer, a hole transporting layer, a light emitting layer (emitting material layer) to improve light emission efficiency. In addition, it can be configured as a multiple layer of 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 part is formed on the first substrate 301 on which the thin film transistor (TFT) and the organic light emitting device (OL) are formed. For example, a seal layer 324 that protects the display element is formed on the upper electrode 323. The sealing layer 324 may include a plurality of layers or may be bonded to the second substrate 302. The second substrate 302 may be a sealing 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 various known sealing parts may be used to prevent inflow of oxygen or moisture. Can be applied.

  In addition, the configuration of the organic light emitting display according to the present invention is not limited to that illustrated, 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. The touch panel 400 may include an integrated type touch panel 400.

  When the touch panel 400 is an exterior touch panel 400, the touch panel 400 may have a separate configuration that is separated from the display panel 300. A transparent adhesive layer (not shown) is formed between the touch panel 400 and the display panel 300.

  Here, the touch panel 400 may be formed in a separate configuration separated from the cover substrate 200 or may be integrally formed with the cover substrate 200. When the touch panel 400 is formed with a separate configuration separated from the cover substrate 200, a transparent adhesive layer (not shown) is formed between the touch panel 400 and the cover substrate 200. When the touch panel 400 is formed integrally with the cover substrate 200, a sensing electrode or the like is formed on the back surface of the cover substrate 200. That is, a separate adhesive layer is unnecessary between the touch panel 400 and the cover substrate 200.

  When the touch panel 400 is a built-in touch panel 400, the touch panel 400 is formed integrally with the display panel 300. That is, a separate adhesive layer is unnecessary between the touch panel 400 and the display panel 300. The touch panel 400 may be formed as an on-cell type or an in-cell type.

  When the touch panel 400 is an on-cell type, a sensing electrode or the like is formed on the upper surface of the display panel 300. In detail, a sensing electrode and the like are directly formed on a substrate disposed on the display panel 300. In addition, like the exterior touch panel 400, the touch panel 400 is formed with a separate configuration separated from the cover substrate 200, or formed integrally with the cover substrate 200.

  When the touch panel 400 is an in-cell type, a sensing electrode or the like is formed between the first substrate and the second substrate of the display panel 300. That is, when an element is formed on the display panel 300, a sensing electrode and the like are formed together. At this time, the cover substrate 200 is formed in a separate configuration separated from the touch panel 400. In addition, a transparent adhesive layer is formed between the cover substrate 200 and the display panel 300.

  Hereinafter, the touch panel 400 will be described in more detail with reference to FIGS. 4 and 5. 4 and 5 illustrate an example of an external touch panel formed with a separate configuration separated from the cover substrate 200, the configuration of the touch panel 400 is not limited to that illustrated. As described above, both the exterior type and the built-in type touch panel can be applied to the touch panel 400.

  As shown in FIGS. 4 and 5, the touch panel 400 can be divided into a display area (AA) where light is transmitted and a non-display area (IA) where light is not transmitted. Specifically, the display area (AA) means an area where a user can input a touch command, and the non-display area (IA) is a concept opposite to the display area (AA). Since it is not activated even when a touch is made, it means an area where a touch command cannot be input.

  As shown in FIG. 4, the touch panel 400 includes a sensing electrode 410 and a wiring 420 disposed on one surface of a touch substrate 401. The touch substrate 401 may include tempered glass, semi-tempered glass, soda lime glass, tempered plastic, or soft plastic, but is not limited thereto.

  The sensing electrode 410 is disposed on the display area (AA), and the wiring 420 is disposed on the non-display area (IA). Although not shown, a printed layer is further formed in the non-display area (IA) of the touch substrate 401. A wiring 420 is formed on the printed layer.

  The sensing electrode 410 may include a conductive material. For example, the sensing electrode 410 is selected from the group consisting of a transparent conductive material, metal, nanowire, photosensitive nanowire film, carbon nanotube (CNT), graphene, conductive polymer, and combinations thereof. Any one can be included.

  The sensing electrode 410 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 different materials. In addition, 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 touch substrate 401, the first sensing electrode 411 and the second sensing electrode 412 need not be in contact with each other. There is. For this purpose, an insulating layer and a bridge electrode are further arranged.

  Specifically, one of the first sensing electrode 411 and the second sensing electrode 412 is disposed under the insulating layer, and the other is the bridge electrode formed on the insulating layer. Are electrically connected to both ends of each other. Accordingly, the first sensing electrode 411 and the second sensing electrode 412 are electrically connected to each other by the bridge electrode and the insulating layer without being short-circuited and short-circuited.

  The first sensing electrode 411 and the second sensing electrode 412 may be disposed on the display area AA and serve as a sensor that senses a touch. In detail, the first sensing electrode 411 extends in one direction on the display area AA, and the second sensing electrode 412 extends in a direction different from the one 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.

  The first wiring 421 and the second wiring 422 are connected to a printed circuit board (not shown). In detail, the first wiring 421 and the second wiring 422 may be configured such that the touch circuit sensed from the first sensing electrode 411 and the second sensing electrode 412 is a printed circuit on which a driving chip (not shown) is mounted. It is transmitted to a substrate (not shown) to execute a touch operation. The printed circuit board (not shown) may be a flexible printed circuit board (FPCB), for example.

  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, a protective layer (not shown) is further formed on the wiring 420. The protective layer (not shown) can protect the wiring 420. Specifically, the protective layer (not shown) can prevent the wiring 420 from being exposed to oxygen and being oxidized, or moisture from penetrating and lowering reliability.

  As shown in 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 tempered glass, semi-tempered glass, soda lime glass, tempered plastic, or soft plastic, but are not limited thereto. The first touch substrate 402 and the second touch substrate 403 can be bonded using a transparent adhesive such as an optical transparent adhesive (OCA).

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

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

  Note that the touch panel 400 is not limited to the drawings and the above description, and may be any input device that can input by using a finger or a stylus pen or the like from the front face of the display device. That is, the touch panel 400 can be applied without limitation as long as it is generally used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, a following example illustrates this invention and does not restrict | limit this invention. In other words, the embodiments of the present invention can be modified in various forms, and the scope of the present invention should not be limitedly interpreted by the following embodiments.

[Example 1]
A cover substrate having a thickness of 0.8 mm was manufactured 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 manufactured 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 manufactured 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 manufactured using polymethylmethacrylate (PMMA) resin.

[Comparative Example 2]
A cover substrate having a thickness of 0.8 mm was manufactured using a copolymer resin of polymethyl methacrylate and styrene (polymethyl methacrylate: styrene = 60 wt%: 40 wt%).

[Comparative Example 3]
A polymethyl methacrylate resin and a polycarbonate resin were coextruded to produce a cover substrate composed of a polymethyl methacrylate 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 manufactured 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 manufactured using a resin composition formed by mixing 85% by weight of polymethylmethacrylate (PMMA) and 15% by weight of rubber (product name: cis-1220). .

[Comparative Example 6]
A cover substrate having a thickness of 0.8 mm was manufactured 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]
A substrate having a polymethylmethacrylate (PMMA) content of 100% by weight manufactured according to Comparative Example 1 was coated with AZO (Aluminum-doped Zinc Oxide) at a thickness of 0.5 μm, and the cover was covered. A substrate was manufactured.

[Experimental example]
The transmittance, haze, dielectric constant, surface hardness, thermal deformation temperature, expansion coefficient under high temperature and high humidity, flexibility, and durability of the cover substrates manufactured by Examples 1-3 and Comparative Examples 1-7. The measurement was performed as follows. The measurement results are shown in Table 1 below.

(1) Transmittance, haze A cover substrate sample is cut into a size of 10 mm × 10 mm, and all transmitted light, diffused light, and parallel light are obtained using a digital haze meter (model name: TC-HIIIDPK / III, manufactured by Tokyo Denshoku). After the measurement, the transmittance and haze were calculated.

(2) Dielectric constant
Using a precision impedance analyzer (model name: E4980A, manufactured by Hitachi), a dielectric constant of a frequency from 1 KHz to 1 MHz was measured with 3 V applied. Samples used for measurement ^were the Pt coated thick 20nm~100nm the upper and lower surfaces with the size of 100mm ² ~900mm 2. As a measurement method, a method was used in which a dielectric constant was calculated by measuring the amount of charge by applying a voltage by contacting each probe to the upper and lower coating layers.

(3) Surface hardness After the pencil tip was flattened with sandpaper 400cW, the pencil was adjusted to 45 degrees on the sample surface and measured. If scratches were generated on the sample surface, the pencil hardness one step lower than the pencil used for the measurement was taken as the surface hardness value.

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

(5) Expansion coefficient under high temperature and high humidity The expansion coefficient was measured after the cover substrate was allowed to stand for 96 hours under conditions of a temperature of 70 ° C. and a relative humidity of 90%. The expansion coefficient was calculated by the following formula.
Expansion rate (%) = {(length of the cover substrate after being left-length of the cover substrate before being left) / (length of the cover substrate before being left)} × 100

(6) Flexibility After cutting the cobo substrate into a size of 100 mm × 30 mm and attaching the cover substrate onto a drum having various radii of curvature, the radius R of the drum immediately before the cover substrate is broken is defined as the degree of bending. Flexibility was evaluated.

(7) Durability A 22 g SUS ball was dropped, and the height at which breakage occurred was measured.

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

  Further, from Table 1, the cover substrates of Examples 1 to 3 have a high dielectric constant of 4.0 or higher, which is advantageous in realizing touch sensitivity and touch performance as compared with the cover substrates of Comparative Examples 1 to 4 and 7. It turns out that it is.

  Moreover, it can be seen from Table 1 that the cover substrates of Examples 1 to 3 have a high surface hardness of 9H. In comparison, Comparative Examples 2 to 5 and 7 have low surface hardness and are not suitable for the cover substrate.

  Moreover, from Table 1, it was confirmed that the cover substrates of Examples 1 to 3 had a heat distortion temperature exceeding 70 ° C. In general, the cover substrate has a printing drying process temperature of 70 ° C. or outside, so that the heat deformation temperature must be formed at a temperature of 70 ° C. or higher in order to ensure the processability.

  Moreover, from the said Table 1, although the cover substrate of Examples 1-3 is very low as 0.01% of the size change rate (expansion rate) in a high-temperature, high-humidity environment, Comparative Examples 1-2, 4- 7 shows that the size change rate is higher than that of Examples 1 to 3.

  Further, from Table 1, the cover substrates of Examples 1 to 3 have excellent formability because the degree of bending is 45 mm or less, while Comparative Example 6 has a low degree of bending and is difficult to apply to a flexible substrate. I understand that there is. Therefore, according to the embodiment, a flexible substrate having a high dielectric constant and excellent flexibility can be produced.

  Features, structures, effects, and the like exemplified in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to one embodiment. In addition, the features, structures, effects, etc. exemplified in each embodiment can be implemented by combining or modifying other embodiments by a person having ordinary knowledge in the field to which the embodiment belongs. The contents relating to various combinations and modifications should be construed as being included in the scope of the present invention.

  In addition, the embodiment has been described mainly with reference to the embodiment, but this is merely an example and does not limit the present invention. It is obvious that a person having ordinary knowledge in the field to which the present invention belongs can make various modifications and applications not exemplified above without departing from the essential characteristics of the present embodiment. is there. For example, each component specifically presented in the embodiments can be modified and implemented. And the difference which concerns on such a deformation | transformation and application should be construed to be included in the scope of the present invention defined in the appended claims.

Claims (10)

A display panel including a first substrate and a second substrate;
A cover substrate disposed on the display panel and including a carbonate compound;
The carbonate compound has the following formula:

(Wherein R _{1 to} R ₄ are each independently hydrogen or alkyl having 1 to 10 carbon atoms, and the dotted line means a single bond or a non-bond). Display device. The display device according to claim 1, wherein R _{2 to} R ₄ are hydrogen.   The display device according to claim 1, wherein the carbonate compound is ethylene carbonate. The display device according to claim 1, wherein R ₁ is hydrogen.   The display device according to claim 1, wherein the carbonate compound is included in an amount of 5 wt% to 30 wt% of the cover substrate.   The display device according to claim 1, wherein a dielectric constant of the cover substrate is 4.0 to 8.0.   The display device according to claim 1, wherein the cover substrate has a surface hardness of 8H or more.   8. The cover substrate according to any one of claims 1 to 7, wherein the cover substrate has an expansion coefficient of 0.1% or less measured after being left for 96 hours under conditions of a temperature of 70 ° C. and a relative humidity of 90%. The display device described.   The display device according to claim 1, wherein the cover substrate has a bending degree of 45 mm or less.   The display device according to claim 1, wherein the display panel is a flexible display panel, an organic electroluminescence display panel, or a liquid crystal display panel.

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