Display device

Abstract

A display device includes a display panel; and a cover window including a density control area and positioned to correspond to a transmission direction of light emitted from the display panel, a refractive index of the density control area gradually varying, wherein the refractive index of the density control area gradually varies through voids.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2021-0173637, filed in Korea on December 7, 2021, the entire contents of which are incorporated herein by reference for all purposes, as if fully set forth herein. Technical Field

[0003] The present invention relates to display devices, and more particularly, to display devices capable of achieving superior color by preventing the displayed image from being modulated by reflection of external light. Background Technology

[0004] With the advent of the information age, the display field has developed rapidly. In response, liquid crystal display devices (LCDs) and organic light-emitting display devices (OLEDs) have been developed and widely used as flat panel display devices (FPDs) with advantages such as thin shape, light weight and low power consumption.

[0005] Furthermore, in display devices, it is difficult to see the display screen because of surface reflections, such as those from external light, causing surrounding objects or scenery to be reflected onto the screen. As display screens become larger and the surrounding environment brighter, such surface reflections will occur more frequently.

[0006] When surface reflection is severe, the display screen is obscured, and users viewing the screen cannot see the image clearly, which causes great inconvenience.

[0007] To address this issue, polarizing plates and phase retardation plates are placed on the display panel to suppress surface reflections caused by external light (hereinafter referred to as "external light reflection"). However, recently, with the widespread outdoor use of display devices as portable display devices (such as smartphones and tablets), there is an urgent need to research ways to improve display characteristics against external light reflection.

[0008] Therefore, it also includes anti-reflective films, which are mainly divided into AG (anti-glare) type films and AR (anti-reflective) type films.

[0009] AG-type films prevent conventional reflection by forming a finely textured surface to induce light refraction and scattering. This fine textured structure is achieved by coating a base film with fine particles ranging from tens to hundreds of micrometers, along with a mixture of adhesive and curing resins, to form a separate surface treatment layer.

[0010] AG anti-reflective coatings have the advantage of being relatively easy to process. However, because AG anti-reflective coatings can cause haze, image quality may be degraded to some extent depending on the size of the grains used, especially in the case of fine pixels.

[0011] Therefore, AG-type anti-reflective films are not suitable for the most recently used display devices, especially since even small display devices are now using them at high resolutions. This makes it even more difficult to apply AG-type films.

[0012] In addition, AR-type antireflective films reduce surface reflectivity by utilizing interference effects, where the wavelength and intensity of light vary according to the refractive index and thickness of the medium.

[0013] Therefore, AR-type films have a stacked structure of several layers (e.g., 2 to 5 layers) with different refractive indices. The stacked structure can be formed by using methods such as bonding of coating films, direct deposition, sputtering, ion plating, ion beam deposition, or methods such as gravure coating, microgravure coating, roll coating, bar coating, dip coating, etc. for coatings used for each layer.

[0014] AR-type antireflective films have the following problems: significant losses during the stacking process, reduced mass production feasibility due to the numerous steps involved, and high price. Summary of the Invention

[0015] Therefore, the present invention relates to a display device that substantially eliminates one or more problems caused by the limitations and disadvantages of related technologies.

[0016] The advantage of this invention is that it provides a display device including a cover glass that can be simple to manufacture, inexpensive, and suppresses external light reflection.

[0017] Another advantage of the present invention is that it provides a light-emitting diode display that can improve display characteristics, such as visibility, by suppressing external light reflection.

[0018] Additional features and advantages of this disclosure will be set forth in the following description, and some of these additional features and advantages will become apparent from the description, or may be learned by practice of this disclosure. These and other advantages of this disclosure will be realized and obtained through the structures particularly pointed out in the written description and its claims and drawings.

[0019] To achieve these and other advantages and for the purposes of this disclosure, as implemented and broadly described herein, a display device includes: a display panel; and a cover window including a density control region and positioned to correspond to the transmission direction of light emitted from the display panel, the refractive index of the density control region gradually changing, wherein the refractive index of the density control region gradually changes through gaps.

[0020] Furthermore, a display device is provided, comprising: a display panel; and a cover window including a density control region and located on the image display surface of the display panel, wherein a gap is provided in the density control region such that the refractive index of the density control region gradually changes from a first refractive index to a second refractive index from a first side of the density control region to a second side of the density control region opposite to the first side, the first side being the side of the density control region in contact with the medium surrounding the display device, wherein the difference between the first refractive index and the refractive index of the material constituting the cover window is less than or equal to a first predetermined threshold, and wherein the difference between the second refractive index and the refractive index of the medium is less than or equal to a second predetermined threshold.

[0021] It should be understood that the foregoing general description and the following detailed description are exemplary and illustrative, and are intended to provide further explanation of the claimed contents of this disclosure. Attached Figure Description

[0022] The accompanying drawings are included to provide a further understanding of this disclosure and are incorporated in and form a part of this specification. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. In the drawings:

[0023] Figure 1 This is a schematic diagram illustrating a plurality of sub-pixels in a display device according to an embodiment of the present invention;

[0024] Figure 2A This is a schematic cross-sectional view of a cover window according to an embodiment of the present invention;

[0025] Figure 2B This is a schematic diagram illustrating the anti-reflection principle of the cover window according to an embodiment of the present invention;

[0026] Figure 3A These are photographs that demonstrate the visibility of traditional display devices;

[0027] Figure 3B This is a photograph showing a display device including a cover glass according to an embodiment of the present invention;

[0028] Figures 4A to 4D This is a cross-sectional view illustrating the steps of forming the density control region of the cover window according to an embodiment of the present invention; and

[0029] Figure 5 It is along Figure 1 The cross-sectional view taken by line II-II' shows the structure of a unit pixel including three sub-pixels according to an embodiment of the present invention. Detailed Implementation

[0030] In the following description, embodiments of the present invention will be illustrated with reference to the accompanying drawings.

[0031] Figure 1 This is a schematic diagram illustrating a plurality of sub-pixels in a display device according to an embodiment of the present invention.

[0032] like Figure 1 As shown, the display device 100 according to an embodiment of the present invention may include a display panel 110 and a cover window (or cover glass) 200.

[0033] For ease of explanation, the orientation in the attached drawings is defined as follows: with the display surface of the display panel 110 facing forward, the cover window 200 is positioned in front of the display panel 110.

[0034] More specifically, the display panel 110 may be a display panel of a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), an electroluminescent display (ELD), or an organic light-emitting diode display (OLED).

[0035] In the following description, for ease of explanation, a display device 100 that emits light by means of the energy generated when an exciton generated by the combination of electrons and holes in the light-emitting layer descends from the excited state to the ground state will be used as an example.

[0036] In the display panel 110, a unit pixel P can be defined as including a red sub-pixel R-SP, a green sub-pixel G-SP, and a blue sub-pixel B-SP. Each of the sub-pixels R-SP, G-SP, and B-SP can include a light-emitting area EA, and a ridge can be set along the edge of the light-emitting area EA. Figure 5 (119) to form the non-luminescent region NEA.

[0037] In this case, red sub-pixels R-SP, green sub-pixels G-SP, and blue sub-pixels B-SP can be alternately set in the horizontal direction as the row direction, and each of the multiple red sub-pixels R-SP, green sub-pixels G-SP, and blue sub-pixels B-SP can be arranged in the vertical direction.

[0038] Therefore, each of the red sub-pixel R-SP, green sub-pixel G-SP, and blue sub-pixel B-SP can have a structure arranged in a strip.

[0039] For ease of illustration, the red sub-pixel R-SP, green sub-pixel G-SP, and blue sub-pixel B-SP are shown positioned side by side with the same width, but the red sub-pixel R-SP, green sub-pixel G-SP, and blue sub-pixel B-SP can have various structures with different widths.

[0040] At this point, switching thin-film transistors and driving thin-film transistors STr and DTr can be disposed on the non-light-emitting region NEA of each of the sub-pixels R-SP, G-SP, and B-SP. This includes the first electrode ( Figure 5 111), Emissive layer ( Figure 5 113) and the second electrode ( Figure 5 115) light-emitting diode ( Figure 5 The ED can be located on the luminous region EA of each of the sub-pixels R-SP, G-SP and B-SP.

[0041] Here, the switching thin-film transistor STr and the driving thin-film transistor DTr can be connected to each other, and the driving thin-film transistor DTr can be connected to the light-emitting diode (LED). Figure 5 (ED).

[0042] More specifically, gate line GL, data line DL, and power line VDD can be disposed on substrate 101 to define each of sub-pixels R-SP, G-SP, and B-SP.

[0043] A switching thin-film transistor (STr) can be formed in the intersection region of the gate line GL and the data line DL, and the switching thin-film transistor STr can be used to select each of the sub-pixels R-SP, G-SP and B-SP.

[0044] A switching thin-film transistor STr may include a gate electrode SG branching from the gate line GL, a semiconductor layer (not shown), a source electrode SS, and a drain electrode SD.

[0045] Furthermore, the driving thin-film transistor DTr can be used to drive the light-emitting diodes of each of the sub-pixels R-SP, G-SP, and B-SP selected by the switching thin-film transistor STr. Figure 5 (ED). Driving a thin-film transistor DTr may include: a gate electrode DG connected to the drain electrode SD of a switching thin-film transistor STr; a semiconductor layer ( Figure 5 103); the source electrode DS connected to the power line VDD; and the drain electrode DD.

[0046] The drain electrode DD of the driving thin-film transistor DTr can be connected to a light-emitting diode (LED). Figure 5 The first electrode of the ED) Figure 5 (of 111).

[0047] Emissive layer ( Figure 5 113) can be inserted into the light-emitting diode (LED). Figure 5 The first electrode of the ED) Figure 5 111) and the second electrode ( Figure 5 Between 115 and 115.

[0048] Furthermore, the cover window 200 may be located on the front surface of the display panel 110 (e.g., the image display surface) to correspond to the light-emitting layer ( Figure 5 The transmission direction of the emitted light (113). According to an embodiment of the present invention, the cover window 200 can gradually change the refractive index of the incident light to prevent a sudden change in the refractive index of the medium, which is a fundamental condition for reflection, thereby preventing reflection.

[0049] Therefore, the display device 100 according to an embodiment of the present invention can minimize the reflectivity of external light, thereby improving display characteristics.

[0050] Figure 2A This is a schematic cross-sectional view of a cover window according to an embodiment of the present invention, and Figure 2B This is a schematic diagram illustrating the anti-reflective principle of the cover window according to an embodiment of the present invention.

[0051] Figure 3A These are images demonstrating the visibility of traditional display devices, and Figure 3B These are images illustrating the visibility of a display device including a cover window according to an embodiment of the present invention.

[0052] like Figure 2A As shown, the cover glass 200 according to an embodiment of the present invention can be used to protect the display panel ( Figure 1 (110 in the middle). Cover window 200 can protect the display panel ( Figure 1 (110) is protected from external impacts and can transmit light from the display panel ( Figure 1 The light emitted by 110 in the middle makes it visible from the outside on the display panel ( Figure 1 The image shown on 110).

[0053] The cover window 200 can be made of any of the following substrates: sapphire glass, tempered glass, and soda-lime glass, which are impact-resistant and light-transmitting. A feature of the cover window 200 according to an embodiment of the present invention is that it includes a density control region D comprising gaps 210.

[0054] In other words, the cover window 200 according to an embodiment of the present invention can be made of a glass substrate with a certain thickness, and the light-emitting layer ( Figure 5One surface of (113) is defined as a bottom surface (or lower surface) 201, and a density control region D is provided on the side opposite to the bottom surface 201 and has a predetermined thickness from the exposed top surface (or upper surface) 203.

[0055] The density control region D may include a plurality of voids 210, and the number or size of the plurality of voids 210 per unit area may decrease from the top surface 203 of the cover window 200 toward the bottom surface 201, thereby causing a refractive index difference in the density control region D.

[0056] More specifically, in the upper (or upper part) D-Up of the density control region D corresponding to the surface side of the top surface 203 of the cover window 200, the number or size of the voids 210 per unit area can be increased, thus the density of the cover window 200 itself can be low. Furthermore, in the lower (or lower part) D-Down of the density control region D facing the bottom surface 201 of the cover window 200, the number or size of the voids 210 per unit area can be less or smaller compared to the number or size of the voids per unit area in the upper D-Up. Therefore, in the density control region D, since the density of the cover window 200 itself varies according to the size and / or number of voids 210, a refractive index difference can occur.

[0057] Therefore, in the cover window 200, the upper side D-Up of the density control region D has a low refractive index because the density of the cover window 200 itself is formed to be low, and the lower side D-Down of the density control region D has a high refractive index because the density of the cover window 200 itself is formed to be higher than that of the upper side D-Up.

[0058] At this point, as the number and / or size of voids 210 per unit area gradually increase from the lower side D-Down to the upper side D-Up of the density control region D, the refractive index of the density control region D gradually decreases from the lower side D-Down to the upper side D-Up.

[0059] According to an embodiment of the present invention, the density control region D provided in the cover window 200 can be defined as a region that causes a gradual change in refractive index. The refractive index gradually decreases from the lower side D-Down to the upper side D-Up of the density control region D. For example, the lower side D-Down has a refractive index similar to that of the glass forming the cover window 200. For example, the difference between the refractive index of the lower side D-Down and the refractive index of the glass forming the cover window 200 is less than or equal to a first predetermined threshold, which may be 0.1.

[0060] Here, the refractive index of the cover glass 200 made of the glass substrate can be from 1.4 to 1.6. The lower side D-Down of the density control region D can have a refractive index of 1.4 to 1.6, and the upper side D-Up of the density control region D can have a refractive index of 1.0 to 1.1.

[0061] Therefore, the upper side D-Up of the density control region D of the cover glass 200 can have a refractive index similar to that of the air layer (an example of a medium) outside the cover glass 200. For example, the difference between the refractive index of the upper side D-Up and the refractive index of the air layer is less than or equal to a second predetermined threshold, which can be 0.1. Thus, when the upper side D-Up of the density control region D has a refractive index similar to that of the air layer outside the cover glass 200, the boundary between the cover glass 200 and the air layer becomes optically blurred, preventing light refraction at the boundary between the cover glass 200 and the air layer. Therefore, no visibility due to light refraction occurs at the boundary between the cover glass 200 and the air layer.

[0062] like Figure 2B As shown, because the boundary between the cover glass 200 and the air layer becomes optically blurred, total internal reflection due to the difference in refractive index between the two media does not occur, and incident light from the outside can be incident on the display panel as is at all azimuth angles. Figure 1 In (110). Therefore, no reflected light from external light will be generated.

[0063] Since users cannot see the light reflected from the surface, this has the same effect as the disappearance of reflected light, thereby reducing the external light reflectivity.

[0064] By reducing external light reflectivity, visibility degradation caused by external light can be prevented. Furthermore, it can prevent the degradation of display characteristics due to reduced brightness and contrast.

[0065] Table 1 below shows the experimental results of measuring external light reflectance based on the presence or absence of a density control region D, and the external light reflectance is measured from a display panel attached with a cover window 200. Figure 1 The azimuth and brightness of the external light are measured in the same manner as those measured at 110°.

[0066] [Table 1]

[0067] Sample 1 Sample 2 External light reflectance 5.06％ 1.8％

[0068] In Table 1, Sample 1 represents a display device with a cover window (i.e., a conventional cover window) attached without a density control area, and Sample 2 represents a display device with a cover window 200 attached. Figure 1(100) The covering window 200 is provided with a density control region D, in particular, a density control region D that gradually changes the refractive index according to an embodiment of the present invention.

[0069] Referring to Table 1, in Sample 1, the reflectivity of external light reflected from the cover glass to the outside is 5%, and in this case, the visibility of the display screen implemented in the display device is very low.

[0070] On the other hand, Sample 2 has a reflectivity of 1.8%, and it can be seen that the external light reflectivity is reduced by 64% compared to Sample 1. When the reflectivity is less than 3%, the visibility of the display screen is very high, therefore it can be seen that Sample 2 has better visibility in the display panel ( Figure 1 The high visibility of the display screen is achieved in 110).

[0071] In other words, in the display device according to an embodiment of the present invention ( Figure 1 In the case of 100), by positioning the cover window 200 with the density control region D in the transmission direction of the emitted light, the external light reflectivity is less than 2%. Therefore, outdoor visibility can be improved by minimizing the external light reflectivity, while protecting the display panel. Figure 1 (110) is protected from external shocks.

[0072] In particular, by reducing the reflectivity of external light as described above, the display device according to an embodiment of the present invention ( Figure 1 The contrast ratio of 100% was also improved.

[0073] In other words, typically, it is preferred that the display device is such as that described in this embodiment. Figure 1 The display device (100%) has a high contrast ratio for visible light. Here, the contrast ratio can be achieved by the following equation 1.

[0074] Equation 1: Contrast ratio (in a dark room) = Brightness of white light / Brightness of black light.

[0075] However, when reflected light is emitted along with the emitted white and black light in a bright room, the above equation changes slightly. In other words, since the reflected light is reflected to the same extent as both white and black light, the brightness of both white and black light increases as much as the brightness of the reflected light. Therefore, the contrast can be expressed by the following equation 2.

[0076] Equation 2: Contrast ratio (in a bright room) = (brightness of white light + brightness of reflected light) / (brightness of black light + brightness of reflected light).

[0077] Since white light is brighter than black light, the contrast ratio according to Equation 1 is usually greater than 1. Under these conditions, the contrast ratio decreases when the brightness of the reflected light is added to both the numerator and denominator.

[0078] Since higher contrast results in a clearer screen, it is preferable to maintain the highest possible contrast while keeping other conditions constant.

[0079] In particular, as mentioned above, since the contrast ratio is lower in bright rooms than in dark rooms, it is necessary to improve the contrast ratio in bright rooms. In this regard, the display device according to an embodiment of the present invention (… Figure 1 In the 100), by minimizing the brightness of reflected light from external light, it is possible to achieve this without reducing the brightness of light reflected from the display panel. Figure 1 To maximize contrast when the brightness of the output light is within the range of 110).

[0080] Here, for example, the voids 210 of the density control region D provided in the cover window 200 according to an embodiment of the present invention have a particle size (or particle size) of several nanometers to several hundred nanometers, and preferably the particle size is equal to or less than 400 nanometers, 400 nanometers being the actual lower limit of the visible light band.

[0081] As described above, by making the gaps 210 of the density control region D of the cover window 200 have nanometer dimensions, the cover window 200 can reduce reflection caused by external light while maintaining transparency.

[0082] Furthermore, by forming the particle size of the void 210 to be equal to or smaller than the wavelength of visible light, it is possible to prevent the scattering of visible light without reducing the light transmittance.

[0083] Furthermore, preferably, the depth h of the density control region D of the cover window 200 according to an embodiment of the present invention has a range of 50 nm to 800 nm. When the depth h of the density control region D is 50 nm or less, it may not be sufficient to constitute a density control region D, and therefore it may have no effect on improving the external light reflectivity. When the depth h of the density control region D is 800 nm or greater, the number and size of the voids 210 per unit area on the surface of the cover window 200 gradually increase, so the surface rigidity of the density control region D may decrease. Therefore, preferably, the depth h of the density control region D of the cover window 200 is designed to satisfy 50 nm to 800 nm.

[0084] Since reflectivity and transmittance are inversely proportional, the transmittance of the cover window 200 is increased by reducing the reflectivity of external light. Therefore, in the display panel ( Figure 1 The R, G, and B subpixels of 110) Figure 1The brightness achieved in R-SP, G-SP and B-SP has been further improved.

[0085] Figure 3A and 3B The measurement of the display device is based on the presence or absence of a density control area D covering the window 200. Figure 1 A photo with 100% visibility. Figure 3A The image shows a display device including a conventional cover glass, and... Figure 3B This illustrates a display device including a cover glass 200 having a density control region D according to an embodiment of the present invention. Figure 1 (of 100).

[0086] Figure 3A and 3B It is a photograph that measures the visibility of reflected external light in a driven state, and is designed and measured in the same way as the incident azimuth and brightness of external light.

[0087] It can be seen that, with Figure 3A Compared to display devices that include a cover window made of a typical glass substrate, in Figure 3B Display device ( Figure 1 The visibility of the driven image is improved in the 100) implementation.

[0088] Furthermore, it can be seen that, with Figure 3A Compared to China, in Figure 3B The image is clearer because the overlay window 200 according to an embodiment of the present invention has high transmittance and no separate haze phenomenon.

[0089] Therefore, it can be seen that the cover window 200 according to the embodiment of the present invention is completely different from typical anti-glare (AG) and anti-reflective (AR) type anti-reflective films.

[0090] In other words, in the case of AG-type antireflective films, a separate surface treatment layer is also included, giving the AG-type antireflective film a certain amount of haze characteristics, thereby degrading image quality. However, since the cover window 200 according to an embodiment of the present invention has a density control region D on the surface of the cover window itself, the cover window differs in construction from the AG-type antireflective film including a separate surface treatment layer, and in particular, the cover window 200 according to an embodiment of the present invention differs in that the cover window does not have a separate haze component.

[0091] Furthermore, in the case of AR-type antireflective films, since the reflectivity of external light is reduced through destructive interference of light, AR-type antireflective films have a stacked structure of several layers with different refractive indices. However, since the cover window 200 according to an embodiment of the present invention prevents external light reflection through the density control region D of the surface of the cover window 200 itself, the cover window 200 differs significantly from the AR-type antireflective film in handling reflected light, and its construction is also different.

[0092] In particular, because AG and AR type anti-reflective films block the light-emitting layer ( Figure 5 The amount of light emitted by the 113) is approximately 50%, thus requiring high power consumption to provide the desired brightness. However, in the display device according to an embodiment of the present invention ( Figure 1 In the 100), there will be no reduction in brightness due to the cover window 200, therefore the light emission layer ( Figure 5 The light emitted by (113) will not decrease. Therefore, the same power can be used to provide a high-brightness image, and the power consumption required to provide an image with the same brightness can also be reduced.

[0093] As described above, in the display device according to an embodiment of the present invention ( Figure 1 In (100), the cover window 200 with density control region D is positioned to be connected to the light-emitting layer ( Figure 5 The transmission direction of the emitted light corresponds to that of the 113), thus reducing the reflectivity of external light and improving visibility outdoors.

[0094] In addition, it can prevent problems such as reduced brightness and contrast due to external light, and thus deterioration of display characteristics.

[0095] Furthermore, by forming the particle size of the voids 210 set in the density control region D to a few nanometers to several hundred nanometers below the visible light wavelength, the cover window 200 prevents the scattering of visible light to maintain transparency, while only reducing reflection caused by external light.

[0096] Figures 4A to 4D This is a cross-sectional view illustrating the steps of forming the density control region of the cover window according to an embodiment of the present invention.

[0097] like Figure 4A As shown, a glass substrate 200a is prepared. The glass substrate 200a can be made of one of sapphire glass, tempered glass, and soda-lime glass substrates.

[0098] Etching agent E is applied to the surface of glass substrate 200a.

[0099] Etching agent E may consist of at least one of a fluorinated compound, an additive, and an inorganic acid. The fluorinated compound may be one or more selected from hydrogen fluoride (HF), ammonium fluoride (NH4F), and acidic ammonium fluoride (NH4HF2), and the additive may include a fluorinated surfactant or anionic surfactant.

[0100] When a surfactant is added, the penetration of the etchant E can be improved, and problems such as deposits generated during etching adhering to the surface of the glass substrate 200a and causing stains can be prevented, thereby maintaining a very clean surface condition.

[0101] Inorganic acids can be selected from one or more of sulfuric acid (H2SO4), phosphoric acid (H3PO4), hydrogen chloride (HCl), carbonic acid (H2CO3), nitric acid (HNO3), and perchloric acid (HClO4).

[0102] Inorganic acids, as auxiliary materials, can combine with the cations of the glass components to form water-soluble sludge to prevent the sludge from re-adhering to the surface of the glass substrate 200a. They can also increase the oxidation ability of the etchant E to improve the etching ability, and increase the viscosity of the etchant E to prevent the expansion of dents and scratches, thereby improving the surface condition of the glass substrate 200a.

[0103] Thus, as Figure 4B As shown, by applying etchant E to the glass substrate 200a, the Si-O-Si network, which is a glass component constituting the glass substrate 200a, is destroyed.

[0104] The atoms in the glass constituting the glass substrate 200a form an extended three-dimensional network, and the cations in the glass are divided into the following three groups: (1) network forming agents (Si, Zr and B), (2) network modifiers (Na and Ca), and (3) intermediates (Al and Mg).

[0105] The glass undergoes the following reactions using etchant E: (1) hydration and hydrolysis, (2) ion exchange and (3) network recombination.

[0106] As represented by chemical formula 1, water molecules can react with the surface of glass essentially through a hydrolysis reaction involving a reverse condensation reaction.

[0107] Hydrolysis can be accompanied by network decomposition (see chemical formula 2) to form aqueous solutions such as Si(OH)4.

[0108] [Chemical Formula 1]:

[0109] [Chemical Formula 2]: Si-O–Si(OH)3+OH - →Si-O+Si(OH)4 -→Si-O - +Si(OH)4.

[0110] Here, due to the high density of OH - Therefore, network decomposition reactions play an important role. Since ion exchange involves glass-modified cations (Na+)... + K + Ca 2+ and Mg 2+ The exchange of protons with H2O and / or H3O means that protons originate from H2O and / or H3O. + Water molecules in the form of chemical formulas 3 and 4.

[0111] [Chemical Formula 3]: Si-OR + H3O + → Si-OH + R + +H2O.

[0112] [Chemical Formula 4]: Si-OR + H3O + → Si-OH + R + +OH - .

[0113] As shown in the reverse reaction of chemical formula 1, the silanol groups (Si-OH) generated by ion exchange can be dehydrated and condensed into a Si-O-Si network.

[0114] This restructures the glass surface to form a porous material resembling aggregates of colloidal silica particles, a process known as network remodeling.

[0115] In other words, the glass substrate 200a according to an embodiment of the present invention undergoes network reconstruction via an ion exchange reaction of silanol groups (Si-OH) through etchant E. At this time, as... Figure 4C As shown, voids 210 are formed in the glass substrate 200a to allow silanol groups (Si-OH) to permeate into the glass.

[0116] Through this ion exchange reaction, silanol groups (Si-OH) continue to penetrate into the glass substrate 200a, and as... Figure 4D As shown, the cover window 200 according to an embodiment of the present invention has a density control region D, in which a gap 210 is formed at a predetermined depth h.

[0117] At this time, since the ion exchange reaction preferentially occurs at the surface of the glass substrate 200a, the number and size of the voids 210 per unit area decrease from the top surface to the bottom surface of the cover window 200.

[0118] Furthermore, by adjusting the exposure time of the etchant E, the number and size of the voids 210 per unit area of ​​the density control region D can be adjusted to a certain extent. Therefore, the cover window 200 according to an embodiment of the present invention can be formed such that the voids 210 of the density control region D have a particle size of several nanometers to several hundred nanometers equal to or less than 400 nm, and can also be formed such that the density control region D has a depth h of 50 nm to 800 nm.

[0119] The covering window 200 according to this embodiment of the invention comprises glass-modified cation (Na) material throughout. + K + Ca 2+ and Mg 2+ ), and in this case, glass-modified cations (Na) + K + Ca 2+ and Mg 2+ () undergoes ion exchange with silanol groups (Si-OH) only in the density control region D. Therefore, in the density control region D, as a glass-modifying cation (Na) + K + Ca 2+ and Mg 2+ Alkali metals and alkaline earth metals were removed.

[0120] Furthermore, in the display device according to an embodiment of the present invention ( Figure 1 In (100), the cover window 200 with the density control region D is positioned to correspond to the light-emitting layer ( Figure 5 The transmission direction of the light emitted by the cover window 200 can be adjusted, thus reducing the reflectivity of external light. However, as the transmittance of the cover window 200 increases, external light passes through the cover window 200 and is incident on the display device ( ). Figure 1 The display panel of 100) Figure 1 (of 110).

[0121] Figure 5 It is along Figure 1 The cross-sectional view taken by line II-II' shows the structure of a unit pixel of an OLED comprising three sub-pixels according to an embodiment of the present invention.

[0122] like Figure 5 As shown, a unit pixel P may include a red sub-pixel R-SP, a green sub-pixel G-SP, and a blue sub-pixel B-SP, and each of the sub-pixels R-SP, G-SP, and B-SP may include a light-emitting area EA, and a dam 119 may be set along the edge of the light-emitting area EA to form a non-light-emitting area NEA.

[0123] At this time, the semiconductor layer 103 may be located on the switching region TrA of the non-light-emitting region NEA of each of the sub-pixels R-SP, G-SP, and B-SP on the substrate 101. The semiconductor layer 103 may be made of silicon and may include an active region 103a forming a channel at its central portion, and source regions 103b and drain regions 103c doped with high concentrations of impurities on both sides of the active region 103a.

[0124] The gate insulating layer 105 may be located on the semiconductor layer 103.

[0125] The gate electrode DG corresponding to the active region 103a of the semiconductor layer 103 and the gate line GL extending in one direction can be disposed on the gate insulating layer 105.

[0126] Furthermore, the first interlayer insulating layer 109a may be located on the gate electrode DG and the gate line GL. In this case, the first interlayer insulating layer 109a and the gate insulating layer 105 below it may include a first semiconductor layer contact hole 116 and a second semiconductor layer contact hole 116, which expose the source region 103b and the drain region 103c located on both sides of the active region 103a, respectively.

[0127] A source electrode DS and a drain electrode DD can be disposed on a first interlayer insulating layer 109a including a first semiconductor layer contact hole 116 and a second semiconductor layer contact hole 116. The source electrode DS and the drain electrode DD are spaced apart from each other and respectively contact the source region 103b and the drain region 103c exposed through the first semiconductor layer contact hole 116 and the second semiconductor layer contact hole 116.

[0128] The second interlayer insulating layer 109b may be located on the source electrode DS and the drain electrode DD, as well as on the first interlayer insulating layer 109a exposed between the two electrodes DS and DD.

[0129] In this case, the source electrode DS and the drain electrode DD, the semiconductor layer 103 including the source region 103b and the drain region 103c in contact with the source electrode DS and the drain electrode DD, and the gate insulating layer 105 and the gate electrode DG located on the semiconductor layer 103 can form a driving thin film transistor DTr.

[0130] In addition, switching thin-film transistors (TFTs) Figure 1 The STr can have the same structure as the driving thin film transistor DTr and can be connected to the driving thin film transistor DTr.

[0131] Furthermore, in the accompanying drawings, a driving thin-film transistor DTr as a top-gate transistor is shown as an example, wherein the semiconductor layer 103 is made of a polycrystalline silicon semiconductor layer or an oxide semiconductor layer, and as a modification, the driving thin-film transistor DTr can be configured as a bottom-gate transistor formed of pure amorphous silicon and impurity amorphous silicon.

[0132] In this case, when the semiconductor layer 103 is made of an oxide semiconductor layer, a light blocking layer (not shown) may be further disposed below the semiconductor layer 103, and a buffer layer (not shown) may be disposed between the light blocking layer (not shown) and the semiconductor layer 103.

[0133] The second interlayer insulating layer 109b may include a drain contact hole PH that exposes the drain electrode DD of the driving thin-film transistor DTr. The first electrode 111 may be located on the second interlayer insulating layer 109b, connected to the drain electrode DD of the driving thin-film transistor DTr through the drain contact hole PH, and may form the anode of the light-emitting diode ED, which is made of, for example, a material having a relatively high work function value.

[0134] A first electrode 111 can be arranged for each of the sub-pixels R-SP, G-SP, and B-SP, and a dam 119 can be located between the first electrodes 111 of the sub-pixels R-SP, G-SP, and B-SP. In other words, the first electrode 111 can have a separate structure for each of the sub-pixels R-SP, G-SP, and B-SP, and the dam 119 serves as the boundary of each of the sub-pixels R-SP, G-SP, and B-SP.

[0135] Furthermore, the light-emitting layer 113 may be located on the first electrode. The light-emitting layer 113 may include a monolayer made of a light-emitting material and a hole injection layer to improve luminous efficiency. To improve luminous efficiency, the light-emitting layer includes multiple layers, including a hole injection layer, a hole transport layer, a light-emitting material layer, an electron transport layer, and an electron injection layer.

[0136] In the display device 100 according to an embodiment of the present invention, the same white light can be emitted from the light-emitting layer 113 of each of the sub-pixels R-SP, G-SP and B-SP.

[0137] The second electrode 115, forming the cathode, can be located on the entire surface of the light-emitting layer 113. The second electrode 115 can be made of, for example, a material having a relatively small work function value.

[0138] In the display device 100, when a predetermined voltage is applied to the first electrode 111 and the second electrode 115 according to a selected signal, holes injected from the first electrode 111 and electrons provided from the second electrode 115 are transferred to the light-emitting layer 113 to form excitons, and when the excitons transition from the excited state to the ground state, they generate and emit light in the form of visible light.

[0139] Here, the display device 100 according to an embodiment of the present invention may be a top-emitting display device, wherein white light emitted from the light-emitting layer 113 passes through the second electrode 115 and is emitted to the outside, and finally, the display device 100 realizes any image.

[0140] In top-emitting display devices, switching thin-film transistors and driving thin-film transistors (TFTs) Figure 1 The STr and DTr of the thin-film transistors can be widely disposed below the dam 119 and the first electrode 111. Therefore, compared with bottom-emitting display devices, the advantage lies in the thin-film transistors (STr and DTr). Figure 1 The design area of ​​STr and DTr is wide.

[0141] In this case, the first electrode 111, which serves as the anode, can be formed from a metallic material with high reflectivity, such as aluminum (Al) or a stacked structure of aluminum (Al) and ITO, and the second electrode 115, which serves as the cathode, can be formed from a transparent metallic material such as ITO or IZO or a translucent metallic material such as magnesium (Mg) or silver (Ag), so that each of the red, green and blue light emitted from the light-emitting layer 113 can be transmitted.

[0142] The passivation layer 102 in thin film form and the packaging substrate 140 can be sequentially located on the thin film transistor ( Figure 1 The passivation layer 102 is used to protect the light-emitting layer 113, which is susceptible to external moisture or oxygen, by preventing moisture from penetrating into each of the sub-pixels R-SP, G-SP, and B-SP.

[0143] In addition, the passivation layer 102 can be used to protect the thin-film transistor (TFT). Figure 1 The passivation layer 102 protects the STr and DTr and the light-emitting diode ED from external impacts, and can also be used to bond the substrate 101 and the package substrate 140.

[0144] Therefore, the display device 100 is packaged.

[0145] At this time, the color conversion layer 106 may be located on the inner side (or inner surface) of the packaging substrate 140, and the color conversion layer 106 may include color filter patterns R-CF, G-CF and B-CF positioned corresponding to the sub-pixels R-SP, G-SP and B-SP.

[0146] Color conversion layer 106 is used to convert the color of white light emitted from light-emitting layer 113. Red color filter pattern R-CF, green color filter pattern G-CF and blue color filter pattern B-CF can be arranged to correspond to the light-emitting areas EA of R sub-pixel R-SP, G sub-pixel G-SP and B sub-pixel B-SP, respectively.

[0147] Therefore, the display device 100 according to an embodiment of the present invention emits R color, G color and B color for each sub-pixel R-SP, G-SP and B-SP to achieve full color with high brightness.

[0148] The cover window 200 may be located on the outer side (or outer surface) of the packaging substrate 140. The touch sensor 120 and the polarizing plate 130 may be arranged sequentially from the packaging substrate 140 between the packaging substrate 140 and the cover window 200.

[0149] Here, since the cover window 200 according to an embodiment of the present invention includes a density control region D that causes a change in refractive index according to a gradual change in density, the external light reflectivity can be reduced, thereby improving visibility outdoors.

[0150] In addition, it can prevent problems such as reduced brightness and contrast due to external light and deterioration of display characteristics.

[0151] In addition, the touch sensor 120 located outside the package substrate 140 may include multiple touch sensing lines (not shown) and multiple touch driving lines (not shown), wherein the multiple touch driving lines are formed to intersect with the touch sensing lines without contacting the touch sensing lines.

[0152] The touch sensor 120 can detect capacitance changes at the intersection of the touch sensing line and the touch driving line to determine whether the intersection is touched, with an insulating layer (not shown) placed between the touch sensing line and the touch driving line.

[0153] The polarizing plate 130 can be located on the touch sensor 120, that is, between the cover window 200 and the touch sensor 120. The polarizing plate 130 transmits only light that vibrates in the same direction as the polarization axis of the polarizing plate 130 from the light guided to the polarizing plate 130, and uses a suitable medium to absorb or reflect light that vibrates in other directions, thereby producing light that vibrates in a specific direction.

[0154] The polarizing plate 130 is used to prevent the following problems: the deterioration of visibility due to the increased reflectivity caused by the light-emitting layer 113 and various lines or electrodes, and the visual identification of line or electrode patterns.

[0155] Specifically, in the display device 100 according to an embodiment of the present invention, since the density control region D is provided on the surface of the cover window 200, the boundary between the cover glass 200 and the air layer becomes optically blurred. Therefore, incident light from the outside is not totally reflected due to the refractive index difference between the two media, but is incident into the display device 100 as is. In this case, the incident light that enters the display device 100 through the density control region D of the cover window 200 is partially absorbed by the polarizing plate 130. Therefore, the display device 100 can be used to prevent the incident light from being transmitted to the outside again.

[0156] As described above, in the display device 100 according to an embodiment of the present invention, the external light reflectivity can be reduced and the visibility can be improved by arranging a cover glass 200 with a density control region D arranged in accordance with the transmission direction of light emitted through the light-emitting layer 113. The density control region D causes a change in refractive index as the density gradually changes.

[0157] In addition, it can prevent problems such as reduced brightness and contrast due to external light and deterioration of display characteristics.

[0158] Furthermore, by setting voids in density control region D ( Figure 4D The particle size of 210 is formed to be a few nanometers to hundreds of nanometers below the visible light wavelength. The cover window 200 prevents the scattering of visible light to maintain transparency, while only reducing the reflectivity of external light.

[0159] In particular, since the density control area D is formed by adjusting the density of the cover window 200 itself, it does not require a separate surface treatment layer, thereby improving process efficiency.

[0160] It will be apparent to those skilled in the art that various modifications and variations can be made to the invention without departing from its spirit or scope. Therefore, it is intended that the invention cover modifications and variations thereof, provided they fall within the scope of the appended claims and their equivalents.

Claims

1. A display device, comprising: Display panel; as well as The cover window includes a density control area and is positioned to correspond to the transmission direction of light emitted from the display panel. The refractive index of the density control region gradually changes through multiple voids disposed within the density control region. The density control region includes: The upper region includes the top surface of the cover window and includes a first plurality of the plurality of gaps. The intermediate region is located below the upper region and includes a second plurality of the plurality of gaps, and The lower region is located below the middle region and includes a third or more gaps among the plurality of gaps. The refractive index of the density control region gradually increases from the upper region to the lower region. The upper region, the middle region, and the lower region are single pieces, and Wherein, a gap located at the interface between the upper region and the middle region in the first plurality of gaps is combined with a gap located at the interface between the upper region and the middle region in the second plurality of gaps to form a gap.

2. The display device according to claim 1, wherein, The top surface of the cover window is opposite to the bottom surface of the cover window facing the display panel.

3. The display device according to claim 2, wherein, From the upper region to the lower region of the density control region, the number or size of the plurality of voids per unit area decreases.

4. The display device according to claim 3, wherein, The top side of the upper region of the density control area has a first density, and the difference between the refractive index of the top side and the refractive index of the air layer outside the cover window is less than or equal to a first predetermined threshold. The lower part of the density control region has a second density that is greater than the first density, and the difference between the refractive index of the lower part and the refractive index of the glass forming the cover window is less than or equal to a second predetermined threshold.

5. The display device according to claim 1, wherein, The pores have a particle size of 400 nm or smaller.

6. The display device according to claim 1, wherein, The density control region has a depth of 50 nm to 800 nm.

7. The display device according to claim 1, wherein, In the density control region, alkali metals and alkaline earth metals, which are glass-modified cations in the cover window, are removed.

8. A display device, comprising: Display panel; as well as A cover window, which includes a density control area, is located on the image display surface of the display panel. The density control region includes multiple gaps, such that the refractive index of the density control region gradually changes from a first refractive index to a second refractive index from a first side to a second side opposite to the first side. The first side is the side of the density control region that contacts the medium surrounding the display device. Wherein, the difference between the second refractive index and the refractive index of the material constituting the cover window is less than or equal to a first predetermined threshold. Wherein, the difference between the first refractive index and the refractive index of the medium is less than or equal to a second predetermined threshold. The density control region includes: The upper region includes the first side of the density control region and includes a first plurality of voids among the plurality of voids. The intermediate region is located below the upper region and includes a second plurality of the plurality of gaps, and The lower region, located below the middle region, includes the second side of the density control region, and the lower region includes a third of the plurality of voids. The refractive index of the density control region gradually increases from the upper region to the lower region of the density control region, and The size of the second plurality of gaps is larger than the size of the third plurality of gaps, and the size of the second plurality of gaps is smaller than the size of the first plurality of gaps.

9. The display device according to claim 8, wherein, The medium is air.

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