Light unit and display device including the same

Abstract

The present disclosure relates to an optical unit and a display device including the same. The optical unit includes: a light source; and an optical member that transmits and converts light emitted from the light source, wherein the optical member includes: a light guide; a low refractive index layer that is disposed on the light guide and has a refractive index lower than that of the light guide; a first capping layer that is disposed on the low refractive index layer; and a wavelength conversion layer that is disposed on the first capping layer and includes quantum dots, and the light guide includes a metal oxide.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0008156, filed on January 22, 2019, which is hereby incorporated by reference for all purposes as if fully set forth herein. Technical Field

[0003] Exemplary embodiments of the present invention generally relate to a light unit, a method for manufacturing the light unit, and a display device including the light unit. Background Art

[0004] A liquid crystal display (LCD) includes a display panel in which a liquid crystal layer is loaded between two substrates. The liquid crystal display controls the orientation of liquid crystal molecules of the liquid crystal layer to adjust the transmittance of light through a pixel unit, thereby displaying an image. Because the display panel of the liquid crystal display is a light receiving element with a non-emissive characteristic, the liquid crystal display includes a light unit on the bottom of the display panel for providing light to the display panel.

[0005] The light unit may include a light source such as a light emitting diode (LED) and an optical member for uniformly transmitting the light emitted from the light source to the display panel. Recently, a method of applying quantum dots to the light unit has been developed. When quantum dots are applied, a wide color range can be provided and color reproducibility can be improved. In addition, there are various advantages, such as high peak brightness can be obtained and power consumption can be reduced. However, the brightness can decrease over time.

[0006] The above information disclosed in this Background section is only for understanding the background of the present inventive concept and therefore it may contain information that does not constitute the prior art. Summary of the invention

[0007] Devices constructed according to exemplary embodiments of the present invention can provide a light unit having improved optical characteristics and a display device including the light unit, and exemplary methods provide a method for manufacturing the light unit.

[0008] Additional features of the inventive concept will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the inventive concept.

[0009] According to an exemplary embodiment, a light unit includes: a light source and an optical component that transmits and converts light emitted from the light source, wherein the optical component includes: a light guide; a low refractive index layer that is disposed on the light guide and has a refractive index lower than that of the light guide; a first capping layer that is disposed on the low refractive index layer; and a wavelength conversion layer that is disposed on the first capping layer and includes quantum dots, and the light guide includes a metal oxide.

[0010] The metal included in the metal oxide may include at least one of Fe, Ti, Co, Cr, Zn, Zr, Sn, V, Mg, Al, Sr, Mn, Cu, and Ni.

[0011] The metal oxide may include: a transparent first metal oxide; and a second metal oxide exhibiting a predetermined color, and a content of the first metal oxide may be greater than a content of the second metal oxide.

[0012] With respect to a direction perpendicular to a side surface of the light guide, the light guide may have a transmittance exceeding 70% in a wavelength range of 400 nm to 700 nm.

[0013] The optical member may further include a second capping layer disposed on the wavelength conversion layer, and the first capping layer and the second capping layer may include an inorganic material.

[0014] The optical member may further include an overcoat layer disposed on the second capping layer, wherein the overcoat layer may include an organic material.

[0015] A display device according to an exemplary embodiment includes: a display panel and a light unit, which supplies light to the display panel, wherein the light unit includes a light source and an optical component, which transmits and converts light emitted from the light source, and the optical component includes a light guide; a low refractive index layer, which is disposed on the light guide and has a refractive index lower than that of the light guide; and a first capping layer, which is disposed on the low refractive index layer, the light guide includes a transparent first metal oxide and a second metal oxide presenting a predetermined color, and the content of the first metal oxide is greater than the content of the second metal oxide.

[0016] With respect to a direction perpendicular to a side surface of the light guide, the light guide may have a transmittance exceeding 70% in a wavelength range of 400 nm to 700 nm.

[0017] The first metal oxide and the second metal oxide may include the same metal.

[0018] The metal included in the first metal oxide and the second metal oxide may include at least one of Fe, Ti, Co, Cr, Zn, Zr, Sn, V, Mg, Al, Sr, Mn, Cu, and Ni.

[0019] The optical member may further include: a wavelength conversion layer disposed on the first capping layer; and a second capping layer disposed on the wavelength conversion layer and including an inorganic material.

[0020] The optical member may further include an overcoat layer disposed on the second capping layer, and the overcoat layer may include an organic material.

[0021] According to an exemplary embodiment, a method for manufacturing an optical unit includes: preparing a light guide including a glass material; heat-treating the light guide; forming a low refractive index layer on the light guide; and forming a first capping layer on the low refractive index layer by using a plasma-assisted chemical vapor deposition method.

[0022] The heat treatment may be performed at 150°C to 350°C.

[0023] Thermally treating the light guide may be performed prior to forming the low refractive index layer.

[0024] Thermally treating the light guide may be performed after forming the low refractive index layer.

[0025] Heat treating the light guide may be performed at 200°C or less.

[0026] As the temperature of the heat treatment of the light guide increases, the heat treatment time can be shortened.

[0027] The heat-treated light guide may include a metal oxide, the metal oxide may include a transparent first metal oxide and a second metal oxide having a predetermined color, and the content of the first metal oxide in the light guide may be greater than the content of the second metal oxide.

[0028] The heat-treated light guide may have a transmittance of more than 70% in the wavelength range of 400 nm to 700 nm with respect to a direction perpendicular to the side surface of the light guide.

[0029] The method for manufacturing the optical unit according to the exemplary embodiment includes: preparing a light guide including a glass material; irradiating light to the light guide; and forming a low refractive index layer and a first capping layer on the light guide, wherein the light has a wavelength of more than 400 nm.

[0030] The method for manufacturing the light unit may further include preparing a light source facing a side of the light guide, wherein light may be emitted from the light source.

[0031] The light guide to which light is radiated may include a metal oxide, the metal oxide may include a transparent first metal oxide and a second metal oxide exhibiting a predetermined color, and a content of the first metal oxide in the light guide may be greater than a content of the second metal oxide.

[0032] The light guide for light radiation may have a transmittance of more than 70% in a wavelength range of 400 nm to 700 nm with respect to a direction perpendicular to a side surface of the light guide.

[0033] According to exemplary embodiments, a light unit having improved optical characteristics, a method for manufacturing the light unit, and a display device including the light unit can be provided. In particular, a light unit can be provided in which the brightness of the light-facing portion does not change or hardly changes even after the passage of time.

[0034] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the inventive concept.

[0036] Figure 1 A display device according to an exemplary embodiment is schematically illustrated.

[0037] Figure 2 For along Figure 1 A cross-sectional view taken along line II-II'.

[0038] Figure 3 is a cross-sectional view of an optical member according to an exemplary embodiment.

[0039] Figure 4 Shown is the heat treatment process performed on an optical component.

[0040] Figure 5 is a transmittance graph for the case where UV-A is irradiated to the light guide.

[0041] Figure 6 is a transmittance graph for the case where UV-B is radiated to the light guide.

[0042] Figure 7 is a transmittance graph for the case where UV-C is radiated to the light guide.

[0043] Figure 8 is a cross-sectional view of a light guide in a manufacturing method according to an exemplary embodiment.

[0044] Fig. 9and Fig.10 are cross-sectional views of some constituent elements of an optical member in a method for manufacturing a light unit according to an exemplary embodiment.

[0045] Fig.11 is a graph showing brightness of an optical member including a light guide according to an exemplary embodiment.

[0046] Fig.12 is a graph showing the brightness of an optical member including a light guide according to a comparative example.

[0047] Fig.13 It is a graph showing the brightness increase rate when the optical members according to the exemplary embodiment and the comparative example are used.

[0048] Fig.14 An image showing an exemplary embodiment in which an inorganic layer is formed on a light guide by using a PECVD process and then a heat treatment is performed thereon.

[0049] Fig.15 is an image of an exemplary embodiment in which the heat treatment is performed at a low temperature. DETAILED DESCRIPTION

[0050] In the following description, for the purpose of explanation, many specific details are set forth to provide a thorough understanding of various exemplary embodiments or implementations of the present invention. As used herein, "implementation" and "implementation" are interchangeable words, which are non-limiting examples of devices or methods using one or more of the present inventions disclosed herein. However, it is apparent that various exemplary embodiments can be practiced without these specific details or with one or more equivalent arrangements. In other cases, well-known structures and devices are shown in block diagram form to avoid unnecessary confusion of various exemplary embodiments. Further, various exemplary embodiments may be different, but do not have to be exclusive. For example, without departing from the present invention, the specific shape, configuration and characteristics of the exemplary embodiment may be used or implemented in another exemplary embodiment.

[0051] Unless otherwise indicated, the illustrated exemplary embodiments are understood to provide exemplary features that vary the details of some ways in which the inventive concept can be implemented in practice. Therefore, unless otherwise indicated, the features, components, modules, layers, films, panels, regions and / or aspects, etc. (hereinafter individually or collectively referred to as "elements") of various embodiments may be combined, separated, exchanged and / or rearranged in other ways without departing from the inventive concept.

[0052] The use of cross-hatching and / or shading is generally provided in the accompanying drawings to clarify the boundaries between adjacent elements. Therefore, unless otherwise indicated, the presence or absence of cross-hatching or shading does not convey or indicate any preference or requirement for a particular material, material property, dimension, proportion, commonality between the illustrated elements, and / or any other idiosyncrasies, attributes, characteristics, etc. of the elements. Further, in the accompanying drawings, the size and relative size of the elements may be exaggerated for clarity and / or descriptive purposes. When the exemplary embodiments may be implemented differently, the specific process order may be performed differently from the order described. For example, two consecutively described processes may be performed substantially simultaneously, or in an order opposite to the order described. Likewise, the same reference numerals represent the same elements.

[0053] When an element or layer is referred to as being "on", "connected to" or "coupled to" another element or layer, it may be directly on, directly connected to or directly coupled to another element or layer, or there may be an intermediate element or layer. However, when an element or layer is referred to as being "directly" "on", "directly connected to" or "directly coupled to" another element or layer, there is no intermediate element or layer. For this reason, the term "connection" may refer to a physical connection, an electrical connection and / or a fluid connection with or without an intermediate element. In addition, the D1 axis, the D2 axis and the D3 axis are not limited to the three axes of a rectangular coordinate system, such as an x-axis, a y-axis and a z-axis, and may be interpreted in a broader sense. For example, the D1 axis, the D2 axis and the D3 axis may be perpendicular to each other, or may present different directions that are not perpendicular to each other. For the purpose of this disclosure, "at least one of X, Y, and Z" and "at least one selected from the group consisting of X, Y, and Z" may be interpreted as only X, only Y, only Z, or any combination of two or more of X, Y, and Z, such as, for example, XYZ, XYY, YZ, and ZZ. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0054] Although the terms "first", "second", etc. may be used herein to describe various types of elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another element. Therefore, without departing from the teachings of the present disclosure, the first element discussed below may be referred to as the second element.

[0055] Spatially relative terms such as "below," "below," "below," "above," "up," "above," "high," "side" (e.g., as in "sidewall"), etc. may be used herein for descriptive purposes, and thus, describe the relationship of one element to another element(s) as illustrated in the figures. In addition to the orientations depicted in the figures, it is expected that spatially relative terms also include different orientations of the device in use, operation, and / or manufacture. For example, if the device in the figure is turned over, the elements described as "below" or "beneath" other elements or features will then be oriented to be "above" the other elements or features. Thus, the exemplary term "below" may include both the above and below orientations. In addition, the device may be oriented in other ways (e.g., rotated 90 degrees or in other orientations), and therefore, the spatially relative descriptors used herein are interpreted accordingly.

[0056] The terms used herein are for the purpose of describing specific embodiments and are not intended to be restrictive. As used herein, it is also expected that the singular forms "a", "a", and "the" include plural forms unless the context clearly indicates otherwise. In addition, the terms "comprises", "comprising", "includes", and / or "including" when used in this specification indicate the presence of narrated features, integers, steps, operations, elements, components, and / or groups thereof, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should also be noted that, as used herein, the terms "substantially", "about", and other similar terms are used as approximate terms, and are not used as terms of degree, and, therefore, are used to take into account the inherent deviations of the values ​​measured, calculated, and / or provided that are recognized by those of ordinary skill in the art.

[0057] Various exemplary embodiments are described herein with reference to cross-sectional illustrations and / or exploded illustrations as schematic illustrations of idealized exemplary embodiments and / or intermediate structures. Therefore, variations from the illustrated shapes are expected due to, for example, manufacturing techniques and / or tolerances. Therefore, the exemplary embodiments disclosed herein should not necessarily be interpreted as being limited to the shapes of the areas illustrated in the particular illustrations, but rather include deviations in shape, for example, caused by manufacturing. As such, the areas illustrated in the figures may be schematic in nature, and the shapes of these areas may not reflect the actual shapes of the areas of the device, and therefore, are not necessarily expected to be restrictive.

[0058] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. Terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense unless explicitly defined as such herein.

[0059] Additionally, in this specification, the phrase "on a plane" means observing the target portion from the top, and the phrase "in a cross section" means observing a cross section formed by vertically cutting the target portion from the side.

[0060] Below, we will refer to Figures 1 to 3 A display device including a light unit according to an exemplary embodiment is described. Figure 1 schematically illustrates a display device according to an exemplary embodiment, Figure 2 For along Figure 1 A cross-sectional view taken along line II-II', and Figure 3 is a cross-sectional view of an optical member according to an exemplary embodiment.

[0061] refer to Figure 1 , schematically illustrates the front side of the display device 1. The display device 1 may be formed in a rectangular shape. A display area DA in which an image is displayed occupies almost the entire area of ​​the front side of the display device 1, and a non-display area NA surrounds the display area DA. The display area DA is called a screen, and the non-display area NA is called a bezel.

[0062] Although the display device 1 and the display area DA are shown to have four angled corners, they may also have rounded corners. In addition, the display device 1 according to the exemplary embodiment may have almost no non-display area NA.

[0063] Figure 2 Pictured Figure 1 The cross section of the display device 1 shown in FIG. 1 is taken along the direction D1. Figure 2 , the light source unit 24 is provided at one edge of the display device 1. In the display device 1, the periphery of the edge where the light source unit 24 is provided is referred to as a light incident portion, and the periphery of the edge at the opposite side of the light incident portion where the light source unit 24 is not provided is referred to as a light facing portion. The light source unit 24 may be provided at at least one edge of the display device 1, but may extend in a vertical direction at the left edge of the display device 1.

[0064] refer to Figure 1 and Figure 2The display device 1 basically includes a display panel 10 and a light unit 20. The display device 1 includes frames 31 and 32 that fix the display panel 10 to the light unit 20 between the display panel 10 and the light unit 20. The display device 1 includes a top chassis 40 that covers the edge of the display panel 10 while protecting the display panel 10 and prevents the display panel 10 from being separated from the light unit 20. The top chassis 40 may be provided only at the edge of the display device in which the light source unit 24 is provided, or may surround the edge of the display device 1. A rear cover 50 is provided at the rear side of the light unit 20, and the rear cover 50 covers a driving device, a power device, etc. that operate the display device 1.

[0065] The display panel 10 may be a liquid crystal display panel in which a liquid crystal layer is formed between two transparent substrates 11 and 12 in which switches, electrodes, and color filters are formed. Polarizers 13 and 14 are attached to surfaces of the substrates 11 and 12, respectively. The display panel 10 adjusts the transmittance of light provided by the optical unit 20 and passing through the polarizers 13 and 14 and the liquid crystal layer under the control of the driving device, and then displays an image.

[0066] The light unit 20 supplying light to the display panel 10 is disposed under the display panel 10. The light unit 20 includes a bottom chassis 21, a support 22, a bracket 23, a light source unit 24, and optical elements including a reflection plate 26, an optical member 27, and an optical plate 28.

[0067] The bottom chassis 21 is a kind of container in which the constituent elements of the light unit 20 are placed or fixed. The bottom chassis 21 may be formed in the shape of a substantially rectangular plate or the like. The bottom chassis 21 may be formed of a metal material such as aluminum, an aluminum alloy, or a plated steel plate. The bottom chassis 21 may be formed of a plastic material such as polycarbonate.

[0068] Optical elements including a reflective plate 26, an optical member 27, and an optical plate 28 are provided on the bottom chassis 21. A support 22 combined with a light source unit 24 is provided at the rear side of the bottom chassis 21 in the light incident portion. A bracket 23 supporting the optical member 27 is provided on the bottom chassis 21 in the light facing portion.

[0069] The support member 22 is a heat dissipation component for fixing the light source unit 24 and, at the same time, transferring heat generated by the light source unit 24 to the bottom chassis 21. The support member 22 may include a metal material having good thermal conductivity, and the light source unit 24 is prevented from being overheated because the heat from the light source unit 24 is quickly transferred to the bottom chassis 21. For example, the support member 22 may be formed by die-casting aluminum or an aluminum alloy.

[0070] The light source unit 24 includes a substrate 241 extending along the light incident portion, and a light source 242 arranged on the substrate 241 with a predetermined gap. The substrate 241 may be a printed circuit board (PCB), and in particular, may be a metal core printed circuit board (MCPCB). The substrate 241 may be fixed to the support 22. The light source 242 is electrically connected to the wiring of the substrate 241, receives power, converts the electric energy into light energy, and then emits light energy. The light source 242 may be a light emitting diode (LED) package, and the LED may emit blue light with high color purity. Blue light may refer to light with a wavelength of about 440 nanometers to about 485 nanometers. For example, the LED may emit a blue light with a peak wavelength of 445 nanometers to 450 nanometers, in particular, a peak wavelength of 447 nanometers. The light source 242 is arranged in a manner that the light emitting side of the light source 242 faces the optical member 27. In addition to the LED package, a point light source or a line light source may also be used as the light source 242.

[0071] The optical member 27 is disposed on the bottom chassis 21, while one edge of the optical member 27 is disposed adjacent to the light source 242. The optical member 27 is used to transmit light emitted from the light source 242 to the display panel 10 by guiding the light to the display panel 10. The optical member 27 is used to change the light having an optical distribution in the form of a point light source or a line light source generated in the light source unit 24 into light having an optical distribution in the form of a surface light source for uniform light distribution. The optical member 27 also converts the wavelength of light emitted from the light source 242. When viewed from the front, the optical member 27 may be larger than the display area DA so as to provide light to the entire display area DA of the display device 1. The optical member 27 may be provided as a single component.

[0072] The reflective plate 26 may be disposed under the optical member 27, ie, between the optical member 27 and the bottom chassis 21. The reflective plate 26 reflects light moving under the optical member 27 to control the light to move toward the display panel 10, thereby improving light efficiency.

[0073] The optical plate 28 may be disposed above the optical member 27. The optical plate 28 may include a scattering plate, a prism plate, and a protective plate. The scattering plate is used to evenly distribute the brightness by scattering the light from the optical member 27, that is, to manufacture a planar light source with uniform brightness. The prism plate adjusts the traveling direction of the light dispersed by the scattering plate so that the traveling direction of the light becomes perpendicular to the display panel 10. The protective plate can be used to protect the prisms of the prism plate from scratches, etc. The protective plate can also be used to diverge the light to widen the viewing angle narrowed by the prism plate. The optical plate 28 may not include any of the scattering plate, the prism plate, and the protective plate, and some may include multiple optical plates. The optical plate 28 may further include a reflective polarizing plate, which can enhance the brightness efficiency by separating, transmitting, and reflecting the polarized light components of the light.

[0074] In the frames 31 and 32 provided to stably fix the display panel 10 and the like, the frame 31 disposed in the light incident portion and the frame 32 disposed in the light facing portion may be different in structure from each other. The display panel 10 may be attached to the optical member 27 and the bracket 23 by adhesive members T1 and T2, such as double-sided tape. The bracket 23 may be attached to the frame 32 by an adhesive member T3. With this structure, the display device 1 may be designed to have a thin thickness.

[0075] Hereinbefore, the entire configuration of the display device 1 has been described. Hereinafter, the optical member 27 of the light unit 20 in the display device 1 according to the exemplary embodiment will be described in detail. Hereinafter, the previously referred drawings will be referred to without any particular reference.

[0076] refer to Figure 3 The optical member 27 includes a light guide 271 as a main constituent element for supplying light from the light source 242 to the display panel 10. In the light guide 271, the periphery adjacent to the light source 242 is referred to as a light incident portion, and the periphery disposed away from the light source 242 is referred to as a light facing portion. The optical member 27 includes a low refractive index layer 273, a first capping layer 275, a wavelength conversion layer 276, a second capping layer 277, and an outer coating layer 278 sequentially stacked on the light guide 271.

[0077] The light guide 271 guides the travel path of the light emitted from the light source 242. The light guide 271 may be a glass light guide. Compared with a plastic light guide such as polymethyl methacrylate (PMMA), a glass light guide is less deformed by heat and moisture and has high strength. When a glass light guide is used, the design freedom of the light unit 20 is increased, so that a thinner light unit 20 and a display device 1 can be provided. Silica-based glass may be used as a glass material of the light guide 271, and the light guide 271 may include silicon dioxide (SiO 2 ), aluminum oxide (Al 2 O 3 ) etc. as the main components.

[0078] The light guide 271 may have a thickness of about 0.5 mm to about 3 mm, but may have a thickness less than 0.5 mm or greater than 3 mm.

[0079] The light guide 271 according to an exemplary embodiment may include a metal oxide. In this case, the metal may include at least one of Fe, Ti, Co, Cr, Zn, Zr, Sn, V, Mg, Al, Sr, Mn, Cu, and Ni. The amount of the metal oxide included in the light guide 271 may be about 0.02 at % to about 0.05 at %.

[0080] The metal oxide according to the exemplary embodiment may include a first metal oxide and a second metal oxide. The first metal oxide may be transparent, and the second metal oxide may have a predetermined color. The second metal oxide may have any color, and for example, may be yellow, green, purple, etc.

[0081] The amount of the first metal oxide included in the light guide 271 may be greater than that of the second metal oxide. The light guide 271 may include the second metal oxide having a predetermined color, but may be transparent and visible because the light guide 271 contains more transparent first metal oxide.

[0082] The first metal oxide and the second metal oxide according to an exemplary embodiment may include the same metal. 1 O x ) and the second metal oxide (M 1 O y ) may include the same metal, but may exhibit different colors depending on the state of the metal ions. 1 O x and M 1 O y In, M 1 may be one metal, and x and y may be different real numbers. For example, when the first metal oxide includes a divalent metal ion and the second metal oxide includes a trivalent metal ion, each metal oxide may exhibit a different color although they are the same metal.

[0083] Specifically, the metal included in the first metal oxide is selected from the group consisting of divalent manganese, divalent titanium, tetravalent titanium, pentavalent titanium, tetravalent chromium, pentavalent chromium, trivalent to hexavalent manganese, tetravalent to hexavalent iron, tetravalent to pentavalent cobalt, trivalent to tetravalent nickel, trivalent copper, divalent zinc, etc. In addition, the metal included in the second metal oxide includes, for example, trivalent titanium, divalent to pentavalent vanadium, divalent to trivalent chromium, divalent manganese, divalent to trivalent iron, divalent to trivalent cobalt, divalent nickel, divalent copper, etc. However, it should be understood that the metals included in the first metal oxide and the second metal oxide are not limited to the above examples, but may include any metal that exhibits different colors depending on metal ions.

[0084] With respect to the direction D1, i.e., the long side direction of one side of the light guide 271, the light guide 271 according to the exemplary embodiment may have a transmittance of more than about 60% for light having a wavelength of 400 nanometers to 700 nanometers, and may, for example, be a transmittance of more than 70%. That is, when the transmittance in the direction perpendicular to the side surface of the light guide 271 is measured, the transmittance may exceed about 60% for light of 400 nanometers to 700 nanometers, or may exceed about 70%. Because the light guide 271 may include a relatively large amount of the first metal oxide in a transparent state compared to the second metal oxide having a predetermined color, the transmittance may be excellent for light having a wavelength of 400 nanometers to 700 nanometers even when the transmittance is measured with respect to the narrow side rather than the wide side.

[0085] The pattern plate 272 is disposed under the light guide 271, and a low refractive index layer 273 having a lower refractive index than the light guide 271 is disposed on the light guide 271. The refractive index of the pattern plate 272 may be the same as that of the light guide 271. The low refractive index layer 273 may include a material having a lower refractive index than a material included in the light guide 271. The low refractive index layer 273 may include an organic material such as acrylic resin, polystyrene, polycarbonate, polyethylene terephthalate, and polyacrylonitrile, and may be coated on the upper surface of the light guide 271. Depending on the exemplary embodiment, the low refractive index layer 273 may include particles dispersed in a resin, such as hollow silica.

[0086] A first interface having a refractive index difference is formed between the low refractive index layer 273 and the light guide 271. The first interface corresponds to the light emission surface OS of the light guide 271, and serves as an interface through which the light L1 guided in the light guide 271 is selectively emitted. When the incident angle formed by the light L1 guided in the light guide 271 and the light emission surface OS exceeds a threshold angle, the light L1 is totally reflected in the first interface and then returns to the light guide 271. On the other hand, when the incident angle of the light L2 or L3 guided in the light guide 271 and the light emission surface OS is less than the threshold angle at which total reflection occurs, at least a portion of the light L2 or L3 passes through the first interface and then leaks from the light guide 271.

[0087] An air layer is formed under the pattern plate 272, and a second interface having a refractive index difference is formed between the pattern plate 272 and the air layer. The reflection angle of the light L1 guided in the light guide 271 is controlled by the pattern of the pattern plate 272. The light L2 or L3 reflected or scattered by the second interface is not completely reflected at the first interface, and at least a portion of the light L2 or L3 may leak from the light guide 271. The pattern plate 272 may be omitted, and instead, the bottom surface of the light guide 271 may be patterned.

[0088] As described above, the light L1 incident on the light entrance surface IS of the light guide 271 leaks through the light emission surface OS of the light guide 271 while being guided in the light guide 271 until reaching the light facing portion from the light entrance portion. The light guide 271 converts the light having an optical distribution in the form of a point light source or a line light source generated from the light source 242 into light having an optical distribution in the form of a surface light source.

[0089] Depending on exemplary embodiments, the optical member 27 may further include a reflective layer RL The reflective layer RL may cover the side surface of the light-facing portion of the light guide 271 to prevent leakage of light guided in the light guide 271 through the side surface of the light-facing portion of the light guide 271 .

[0090] The first capping layer 275 and the wavelength conversion layer 276 are disposed on the low refractive index layer 273. The first capping layer 275 is generally disposed between the wavelength conversion layer 276 and the low refractive index layer 273 to prevent the organic material of the wavelength conversion layer 276 from mixing with the organic material of the low refractive index layer 273. The first capping layer 275 may be used to prevent moisture or oxygen from penetrating into the wavelength conversion layer 276.

[0091] The first capping layer 275 may be deposited by plasma assisted chemical vapor deposition (PECVD) to form an inorganic material such as silicon nitride (SiN x ), silicon oxide (SiO x ) and other deposition.

[0092] The wavelength conversion layer 276 is disposed on the first capping layer 275. The wavelength conversion layer 276 can be formed by coating a composition in which quantum dots QD are dispersed in a dispersion medium such as a resin on the first capping layer 275. Therefore, the wavelength conversion layer 276 can be formed so that the quantum dots QD are dispersed in the resin layer. As the dispersion medium, a transparent material having low light absorption while not affecting the wavelength conversion performance of the quantum dots QD can be used, for example, epoxy resin, polysiloxane, polystyrene, acrylate, etc.

[0093] When the light emitted from the light source 242 is blue light, the quantum dots QD of the wavelength conversion layer 276 may include red quantum dots and green quantum dots. The red quantum dots convert a portion of the blue light into red light having a wavelength of 620 nanometers to 750 nanometers, and the green quantum dots convert a portion of the blue light into green light having a wavelength of 495 nanometers to 570 nanometers. The blue light that is not converted into red light and green light is directly transmitted through the wavelength conversion layer 276. By mixing the blue light, red light, and green light emitted from the wavelength conversion layer 276, the optical member 27 can provide white light to the display panel 10.

[0094] The second capping layer 277 is disposed on the wavelength conversion layer 276, and the outer coating layer 278 is disposed on the second capping layer 277. The second capping layer 277 may include an inorganic material, such as silicon nitride, silicon oxide, etc. The outer coating layer 278 may include an organic material. The second capping layer 277 may prevent the organic material of the wavelength conversion layer 276 and the organic material of the outer coating layer 278 from mixing. The second capping layer 277 may prevent the penetration of moisture or oxygen. The outer coating layer 278 may protect the entire optical member 27.

[0095] The light guide 271 according to the exemplary embodiment may maintain transparency and transmittance of the light guide 271 by including a large amount of transparent metal oxide, and may provide uniform display quality by preventing brightness from changing according to driving of the display device.

[0096] Below, we will refer to Figures 4 to 7 A method for manufacturing a light unit according to an exemplary embodiment is described. Figure 4 shows the heat treatment process performed on the optical component, Figure 5 is a transmittance graph for the case where UV-A is radiated to the light guide, Figure 6 is a transmittance graph for the case where UV-B radiation is applied to the light guide, and Figure 7 is a transmittance graph for the case where UV-C is irradiated to the light guide. Hereinafter, a method of manufacturing the light guide in the optical member will be described in detail, and other components can be manufactured by a method that is obvious to those skilled in the art.

[0097] First, a light guide 271 made of a glass material is prepared. Next, a low refractive index layer 273 including an organic material is formed on the light guide 271, and a first capping layer 275 including an inorganic material is formed on the low refractive index layer 273.

[0098] Subsequently, a process for heat-treating the light guide 271 may be performed. Specifically, the light guide 271 may be heat-treated while the low refractive index layer 273 and the first capping layer 275 are stacked thereon.

[0099] The heat treatment process for the light guide 271 may be performed at a temperature of about 150° C. to about 350° C. The heat treatment process for the light guide 271 may be performed for about 10 minutes to about 100 minutes.

[0100] Depending on the heat-resistant temperature of the low-refractive-index layer 273 , the temperature of the heat treatment process of the light guide 271 may be determined.

[0101] For example, when the heat-resistant temperature of the low refractive index layer 273 exceeds 350° C., the heat treatment process may be performed at any temperature within the described temperature range, and, for example, may be performed at a relatively high temperature. When the heat treatment process is performed at a relatively high temperature, the heat treatment process time may be shortened.

[0102] For example, when the heat resistance temperature of the low refractive index layer 273 is 200° C. or less, the heat treatment process of the light guide 271 may be performed at about 150° C. to about 200° C. When the heat treatment process is performed at a relatively low temperature, the heat treatment process time may be increased. As the temperature of the heat treatment process for the light guide 271 increases, the heat treatment process time may be reduced.

[0103] When the first capping layer 275 is formed after the low refractive index layer 273 is formed on the light guide 271 according to example embodiments, the light guide 271 may be able to exhibit a predetermined color, and transmittance of the light guide 271 may be deteriorated.

[0104] Specifically, a plasma assisted chemical vapor deposition (PECVD) process may be used when forming the first capping layer 275. When the first capping layer 275 may include, for example, silicon nitride, the PECVD process may use SiH 4 NH 3 and N 2 When the first capping layer 275 may include, for example, silicon oxide, SiH 4 and N 2 O reaction gas.

[0105] The reaction gas present in the reaction chamber of the PECVD process can be decomposed into a free radical state by the plasma energy. While the reaction gas is decomposed into the free radical state, light of various wavelengths between about 100 nanometers and about 500 nanometers can be emitted.

[0106] Among these various wavelengths of light, light having a wavelength of about 400 nanometers or less may cause a state change of the metal oxide included in the light guide 271. This will be referred to as Figures 5 to 7 Describe it specifically.

[0107] refer to Figure 5 When UV-A_1, UV-A_2 and UV-A_3 (UV-A) are irradiated to the light guide 271 with different irradiation energies, the transmittance of the light guide 271 does not change significantly compared to before the irradiation of the UV-A wavelength light (reference). Figure 6 , when UV-B_1, UV-B_2, and UV-B_3 (UV-B) are irradiated to the light guide 271 with different radiant energies, the transmittance of the light guide 271 does not change significantly in the visible light band compared to before the irradiation of the UV-B wavelength light (reference), but the transmittance of the light guide 271 is significantly reduced in the wavelength of about 450nm or less. Figure 7, when UV-C_1, UV-C_2, and UV-C_3 (UV-C) are radiated to the light guide 271 at different radiant energies, the transmittance of the light guide 271 is significantly reduced at a wavelength of 400 nm to 700 nm compared to before the irradiation of the light of the UV-C wavelength (reference). That is, the transmittance of the light guide 271 is reduced by the wavelength corresponding to UV-C. For reference, according to the International Commission on Illumination (CIE), ultraviolet light is divided into UV-A at 315-380 nm, UV-B at 280-315 nm, and UV-C at 100-280 nm.

[0108] That is, the transparent first metal oxide (M 1 O x ) can be changed into a second metal oxide (M 1 O y ), and therefore, while the light guide 271 exhibits a predetermined color, the transmittance of the light guide 271 is degraded.

[0109] However, in the method of manufacturing the light unit according to the embodiment, by performing a heat treatment process on the light guide 271 subjected to the PECVD process, the second metal oxide (M 1 O y ) is changed again to the first metal oxide (M 1 O x ). Therefore, the light guide 271 included in the optical member of the exemplary embodiment may be provided in a transparent state.

[0110] Specifically, the light guide 271 before undergoing the PECVD process may include a first metal oxide (M 1 O x ) and the second metal oxide (M 1 O y ), and the first metal oxide (M 1 O x ) may be greater than the second metal oxide (M 1 O y However, when the PECVD process is performed, the first metal oxide (M 1 O x ) can be changed to a second metal oxide (M 1 O y ). Therefore, the light guide 271 may present a predetermined color by the second metal oxide during the manufacturing process. As described above, the light guide property of the light guide 271 including the colored second metal oxide may be reduced, and thus, the amount of light emitted through the light guide 271 may be reduced, and the brightness of the display device may be reduced.

[0111] According to an exemplary embodiment, when heat treatment is performed on the light guide 271, the second metal oxide (M 1 O y ) can be changed again to the first metal oxide (M 1 O x ). Therefore, the light guide 271 according to the exemplary embodiment includes a large amount of transparent first metal oxide (M 1 O x ), and thus, the light guide 271 may be transparent. An optical member using such a light guide 271 may have excellent light guiding properties, and thus, a display device including the optical member may maintain constant brightness.

[0112] Next, refer to Figure 8 , a method for manufacturing a light unit according to an exemplary embodiment will be described. Figure 8 is a cross-sectional view of a light guide in a manufacturing method according to an exemplary embodiment.

[0113] like Figure 8 , the method for manufacturing the light unit according to the exemplary embodiment may include steps for preparing a light guide 271 and performing a heat treatment on the prepared light guide 271 .

[0114] The heat treatment process of the light guide 271 may be performed at a temperature of about 150° C. to about 350° C. The heat treatment process of the light guide 271 may be performed for about 10 minutes to about 100 minutes.

[0115] Since no additional layer is stacked on the light guide 271 in the exemplary embodiment, the process temperature is not limited. The heat treatment process according to the exemplary embodiment may be performed at a relatively high temperature within the temperature range recited above, and may be performed, for example, at 310° C. to 330° C. In this case, the heat treatment process time may be within about 10 minutes to about 30 minutes.

[0116] Next, a low refractive index layer 273 and a first capping layer 275 are sequentially formed on the light guide 271 so that a reference Figure 3 The optical component 27 is described.

[0117] According to example embodiments, even when a PECVD process is performed to form the first capping layer 275 after performing a heat treatment process on the light guide 271 , the light guide 271 may maintain a transparent state.

[0118] The light guide 271 before the heat treatment process may include a first metal oxide (M 1 O x ) and the second metal oxide (M 1 O yWhen the heat treatment process is performed according to the exemplary embodiment, the second metal oxide (M 1 O y ) can be changed into the first metal oxide (M 1 O x That is, the light guide 271 after the heat treatment process may include a majority of the first metal oxide (M 1 O x ) and a small amount of a second metal oxide (M 1 O y ). Therefore, although the PECVD process is performed on the light guide 271 that has undergone the heat treatment process, and thus the first metal oxide (M 1 O x ) is partially changed to a second metal oxide (M 1 O y ), but the first metal oxide (M 1 O x ) may be greater than the second metal oxide (M 1 O y ). Therefore, when the manufacturing method of the exemplary embodiment is used, the light guide 271 may maintain a transparent state even after the PECVD process is performed on the light guide 271.

[0119] Below, we will refer to Fig. 9 and Fig.10 A method for manufacturing a light unit according to an exemplary embodiment is described. Fig. 9 and Fig.10 are cross-sectional views of some constituent elements of an optical member in a method for manufacturing a light unit according to an exemplary embodiment.

[0120] refer to Fig. 9 , a light guide 271 made of a glass material is prepared. Then, a low refractive index layer 273 including an organic material is formed on the light guide 271 , and a first capping layer 275 including an inorganic material is formed on the low refractive index layer 273 .

[0121] When forming the first capping layer 275, a PECVD process may be used. When the first capping layer 275 includes, for example, silicon nitride, the PECVD process may use SiH 4 NH 3 and N 2 When the first capping layer 275 includes, for example, silicon oxide, SiH 4 and N 2 O reaction gas.

[0122] The reaction gas present in the reaction chamber of the PECVD process may be decomposed into a radical state by plasma energy. While the reaction gas is decomposed into a radical state, light of various wavelengths between about 100 nanometers and about 500 nanometers may be emitted. Among these various wavelengths of light, light having a wavelength of about 400 nanometers or less may cause a state change of the metal oxide included in the light guide 271. The light guide 271 after the PECVD process is performed may exhibit a predetermined color, and may, for example, exhibit yellow.

[0123] Meanwhile, the pattern plate 272 is formed at the bottom surface of the light guide 271 , the reflective layer RL is formed at the side surface of the light guide 271 , and then the light source 242 included in the display device is prepared.

[0124] Next, the light source 242 is driven to radiate light to the light guide 271. The light source 242 may emit, for example, blue light, and the blue light may be light having a wavelength of about 440 nanometers to about 485 nanometers. The light source 242 may emit, for example, blue light having a peak wavelength of 445 nanometers to 450 nanometers, and in particular, blue light having a peak wavelength of 447 nanometers.

[0125] The second metal oxide (M) exhibiting a predetermined color 1 O y ) can be changed again into the first metal oxide (M 1 O x ). The light guide 271 subjected to light radiation may be changed to a transparent state again. In this case, the light emitted from the light source 242 may effectively move in the light guide 271 through the pattern plate 272 and the reflective layer RL.

[0126] The first metal oxide (M) included in the light guide 271 subjected to light radiation 1 O x ) may be greater than the second metal oxide (M 1 O y Because the light guide 271 may include a relatively large amount of the first metal oxide in a transparent state compared to the second metal oxide having a predetermined color, the light guide 271 may be considered transparent.

[0127] With respect to the direction D1, i.e., the long side direction of one side of the light guide 271, the light guide 271 subjected to light radiation may have a transmittance of more than about 60% for light having a wavelength of 400 nm to 700 nm, and may, for example, exceed 70%. That is, when the transmittance is measured in a direction perpendicular to the side surface of the light guide 271, the transmittance may exceed about 60% for light of 400 nm to 700 nm.

[0128] Next, refer to Fig.10, a light guide 271 made of a glass material is prepared. Then, a low refractive index layer 273 including an organic material is formed on the light guide 271 , and a first capping layer 275 including an inorganic material is formed on the low refractive index layer 273 .

[0129] The first capping layer 275 may be formed by using a PECVD process, and as described above, the light guide 271 after the PECVD process may exhibit a predetermined color.

[0130] Next, by using another light source A, light may be irradiated to the light guide 271. The light may have a wavelength of about 400 nanometers to about 700 nanometers. The light irradiation may be performed for more than about 24 hours.

[0131] The second metal oxide (M) exhibiting a predetermined color 1 O y ) can be changed again into the first metal oxide (M 1 O x ). The light guide 271 having undergone light radiation may change to a transparent state again.

[0132] The first metal oxide (M 1 O x ) may be greater than the second metal oxide (M 1 O y Since the light guide 271 may include a relatively large amount of the first metal oxide in a transparent state compared to the second metal oxide having a predetermined color, the light guide 271 may be transparent.

[0133] The light guide 271 subjected to light radiation may have a transmittance of more than about 60% and may, for example, exceed 70% for light having a wavelength of 400 nm to 700 nm in the direction D1, i.e., the direction of the long side of one side of the light guide 271. That is, when the transmittance is measured in a direction perpendicular to the side surface of the light guide 271, the transmittance may exceed about 60% for light having a wavelength of 400 nm to 700 nm.

[0134] The present specification describes an exemplary embodiment in which the light radiation process is performed in a state in which the low refractive index layer 273 and the first capping layer 275 are stacked on the light guide 271, but is not limited thereto, and the low refractive index layer 273 and the first capping layer 275 may also be formed after the light radiation process is performed on the light guide 271.

[0135] Below, we will refer to Figures 11 to 13 Exemplary embodiments and comparative examples are described. Fig.11 is a graph showing brightness of an optical member including a light guide according to an exemplary embodiment, Fig.12 is a graph showing the brightness of an optical member including a light guide according to a comparative example, and Fig.13 It is a graph showing the brightness increase rate when the optical members according to the exemplary embodiment and the comparative example are used.

[0136] First, refer to Fig.11 , when a heat treatment process is performed on the light guide according to the exemplary embodiment or a light irradiation process is performed, the display device according to the exemplary embodiment has substantially the same brightness as that of the display device (reference) in the initial driving state even after the PECVD process is performed on the light guide. Because the display device (reference) in the initial driving state includes the light guide in the transparent state, it is determined that the brightness of the display device is constantly maintained even after the lapse of time.

[0137] On the other hand, reference Fig.12 , when the heat treatment process or the light irradiation process is not performed on the light guide according to the comparative example, it is determined that the brightness of the display device including the light guide on which the PECVD process is performed increases with the lapse of time compared to the display device in the initial driving state (reference). The display device in the initial driving state (reference) may include a light guide including a relatively large content of the second metal oxide, and may present a pale yellow color. However, the light guide in which the light emitted from the light source is irradiated by the driving of the device changes to a transparent state again, and thus as Fig.12 Medium display, brightness increased.

[0138] The display device according to the comparative example causes brightness variation, and thus display quality may be non-uniform.

[0139] Next, refer to Fig.13 , with each light guide by radiating light in a region corresponding to the light incident portion, observing the luminance increase rate with respect to the initial state after a predetermined time lapse. Reference indicates a case where a transparent glass light guide is used, and Comparative Example 1 is used on which a light guide is formed by using N 2 O gas was used in the case of a photoconductor subjected to a PECVD process at 180 °C, and Comparative Example 2 was used in which a 2 O gas at 320 °C and N 2 O gas was used for the PECVD process at 180°C, and Comparative Example 3 was used for the photoconductor 2 and NH 3 The gas was at 320 °C and N 2 O gas at 180 ° C. for the PECVD process, and an exemplary embodiment is used thereon by using N 2 O gas at 180 °C for the PECVD process of the photoconductor.

[0140] In the case of the exemplary embodiment, even if the PECVD process is performed on the light guide, the light guide can maintain transparency through the heat treatment process. As a result, it is determined that the same brightness can be exhibited even when a predetermined time elapses in the initial driving state.

[0141] Meanwhile, according to Comparative Examples 1 to 3, when the reaction gas used in the PECVD process changes or the process temperature changes, the content of the second metal oxide may be greater than that of the first metal oxide, and a predetermined color may be presented in the initial driving state. Therefore, when light is radiated in the light incident portion for a predetermined period of time, the second metal oxide is changed again to the first metal oxide in a transparent state, and thus the light guide also becomes transparent, and thus, the brightness increase rate increases to 200%. The driving of the display device causes the brightness change and the degradation of the uniformity of the display quality.

[0142] Below, we will refer to Fig.14 and Fig.15 The transparency of a light guide on which a heat treatment process is performed according to an exemplary embodiment is described. Fig.14 shows an image of an exemplary embodiment in which an inorganic layer is formed on a light guide by using a PECVD process and then a heat treatment is performed thereon, and Fig.15 is an image of an exemplary embodiment in which the heat treatment is performed at a low temperature.

[0143] First, a layer including silicon nitride (SiN x ) and an inorganic layer including silicon oxide (SiO x ) and then perform a heat treatment process at 320° C. for 10 minutes. When the PECVD process is performed, the glass material light guide 271 may have a light yellow color, and since the heat treatment process is performed as in the exemplary embodiment, the light guide 271 is in a transparent state, as shown in FIG. Fig.14 Displayed in.

[0144] Next, a layer including silicon nitride (SiN x ) and an inorganic layer including silicon oxide (SiO x ) of the inorganic layer, and then a heat treatment process was performed at 190° C. for 90 minutes. Fig.14 When the PECVD process is performed, the glass material light guide 271 may have a yellowish color, and due to the heat treatment process performed in the exemplary embodiment, the light guide 271 is in a transparent state, as shown in FIG. Fig.15 as shown in .

[0145] Some advantages that can be achieved by the exemplary embodiments of the present invention and / or the exemplary methods of the present invention include providing a light unit with improved optical characteristics, a method for manufacturing a light unit, and a display device including a light unit. In particular, a light unit can be provided in which the brightness of the light-facing portion does not change or hardly changes even after the passage of time.

[0146] Although certain exemplary embodiments and implementations have been described herein, other embodiments and modifications will be apparent from this description. Therefore, the inventive concept is not limited to these embodiments, but to the broader scope of the appended claims and various obvious modifications and equivalent arrangements apparent to those of ordinary skill in the art.

Claims

1. A light unit, comprising: light source; and an optical member that transmits and converts light emitted from the light source, The optical component comprises: Light guide; a low refractive index layer disposed on the light guide and having a refractive index lower than that of the light guide; A first end-capping layer disposed on the low refractive index layer; and a wavelength conversion layer disposed on the first capping layer and comprising quantum dots, and The light guide comprises a metal oxide, The metal oxides include: a transparent first metal oxide; and a second metal oxide exhibiting a predetermined color, and The content of the transparent first metal oxide is greater than that of the second metal oxide.

2. The light unit according to claim 1, wherein the metal included in the metal oxide includes at least one of Fe, Ti, Co, Cr, Zn, Zr, Sn, V, Mg, Al, Sr, Mn, Cu, and Ni. 3 . The light unit according to claim 1 , wherein the light guide has a transmittance exceeding 70% in a wavelength range of 400 nm to 700 nm with respect to a direction perpendicular to a side surface of the light guide.

4. The optical unit according to claim 1, wherein the optical member further comprises a second capping layer, the second capping layer being disposed on the wavelength conversion layer, and The first capping layer and the second capping layer include an inorganic material.

5. The light unit according to claim 4, wherein the optical member further comprises an outer coating layer, the outer coating layer being disposed on the second capping layer, Wherein the outer coating comprises an organic material.

6. A display device, comprising: Display panel; and a light unit for supplying light to the display panel, The light unit comprises: light source, and an optical member that transmits and converts light emitted from the light source, The optical component comprises: Light guide, a low refractive index layer disposed on the light guide and having a refractive index lower than that of the light guide, and a first end-capping layer, the first end-capping layer being disposed on the low refractive index layer, The light guide includes a transparent first metal oxide and a second metal oxide exhibiting a predetermined color, and The content of the first metal oxide is greater than the content of the second metal oxide. 7 . The display device according to claim 6 , wherein the light guide has a transmittance exceeding 70% in a wavelength range of 400 nm to 700 nm with respect to a direction perpendicular to a side surface of the light guide.

8. A display device according to claim 6, wherein the first metal oxide and the second metal oxide include the same metal, and wherein the metal included in the first metal oxide and the second metal oxide includes at least one of Fe, Ti, Co, Cr, Zn, Zr, Sn, V, Mg, Al, Sr, Mn, Cu and Ni.

9. The display device according to claim 6, wherein the optical member further comprises: a wavelength conversion layer, the wavelength conversion layer being disposed on the first capping layer; and a second capping layer disposed on the wavelength conversion layer and including an inorganic material, and wherein the optical member further includes an overcoat layer disposed on the second capping layer and including an organic material.

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