Patent Description:
A liquid crystal display ("LCD") includes a display panel including a liquid crystal layer positioned between two substrates. The LCD displays an image by controlling a direction of liquid crystal molecules of the liquid crystal layer and adjusting transmittance of light by a pixel unit. Since the display panel of the LCD is a non-emissive element, the LCD typically includes a light unit that provides light to the display panel from the back of the liquid crystal panel.

The light unit may include a light source such as a light emitting diode ("LED") and an optical member for uniformly transmitting light emitted from the light source to the display panel. Recently, a technique for applying quantum dots to the light unit has been developed. An application of quantum dots may provide a wide color gamut and improve color reproducibility. There are also multiple merits such as high peak luminance and reduced power consumption. <CIT> and <CIT> represent prior art useful for understanding the invention.

Exemplary embodiments provide a light unit having improved characteristics and a display device including the same.

A light unit according to the claimed invention includes a light source and an optical member which transmits and converts light emitted from the light source, where the optical member includes a light guide, a low refractive index layer disposed on the light guide and having a smaller refractive index than that of the light guide, and a wavelength conversion layer disposed on the low refractive index layer and including quantum dots, and the low refractive index layer includes a metal.

According to the claimed invention, a thickness of the low refractive index layer is from <NUM> to <NUM> Nanometer [<NUM> angstrom to about <NUM> angstrom].

In an exemplary embodiment, the low refractive index layer may include at least one among silver (Ag), aluminum (Al), a copper-zinc (Cu-Zn) alloy, copper (Cu), and gold (Au).

In an exemplary embodiment, the optical member may further include a first capping layer disposed between the low refractive index layer and the wavelength conversion layer.

In an exemplary embodiment, the first capping layer may include at least one among a silicon nitride, a silicon oxide, an aluminum oxide, and a transparent metal oxide.

In an exemplary embodiment, the first capping layer may include argon (Ar).

In an exemplary embodiment, an opening is defined in the low refractive index layer.

In an exemplary embodiment, the low refractive index layer may include a plurality of regions having different densities from an area occupied by the opening.

In an exemplary embodiment, the optical member may include a light-incident portion adjacent to the light source and a light-facing portion separated from the light-incident portion, and an area occupied by an opening adjacent to the light-incident portion may be smaller than an area occupied by an opening adjacent to the light-facing portion.

In an exemplary embodiment, the optical member may include a light-incident portion adjacent to the light source and a light-facing portion separated from the light-incident portion, and a number of openings adjacent to the light-incident portion may be less than a number of openings adjacent to the light-facing portion.

A display device according to an exemplary embodiment includes a display panel and a light unit which supplies light to the display panel, where the light unit is according to the claimed invention and a refractive index of the low refractive index layer is about <NUM> or less.

In an exemplary embodiment, a threshold angle of the light incident from the light guide to the low refractive index layer may be about <NUM> degrees or less.

According to the exemplary embodiments, the light unit having the improved optical characteristics and the display device including the same may be provided. The exemplary embodiments may provide the light unit with an improved light emission amount and excellent luminance, and the display device including the same.

The above and other exemplary embodiments, advantages and features of this disclosure will become more apparent by describing in further detail exemplary embodiments thereof with reference to the accompanying drawings, in which:.

The invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. In describing the invention, parts that are not related to the description will be omitted. Like reference numerals generally designate like elements throughout the specification.

In addition, the size and thickness of each configuration shown in the drawings are arbitrarily shown for better understanding and ease of description, but the invention is not limited thereto. In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. In the drawings, for better understanding and ease of description, the thicknesses of some layers and areas are exaggerated.

It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. Further, in the specification, the word "on" or "above" means positioned on or below the object portion, and does not necessarily mean positioned on the upper side of the object portion based on a gravitational direction.

Further, throughout this specification, "in a plan view" means when a target part is viewed from the top, and "on a cross-section" means when a cross-section of the target part vertically taken is viewed from the side.

As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms, including "at least one," unless the content clearly indicates otherwise. "Or" means "and/or.

The exemplary term "lower," can therefore, encompasses both an orientation of "lower" and "upper," depending on the particular orientation of the figure. The exemplary terms "below" or "beneath" can, therefore, encompass both an orientation of above and below.

For example, "about" can mean within one or more standard deviations, or within ± <NUM>%, <NUM>%, <NUM>%, <NUM>% of the stated value.

Now, a display device according to an exemplary embodiment is described with reference to <FIG> and <FIG>. <FIG> is a view schematically showing a display device according to an exemplary embodiment, and <FIG> is a cross-sectional view taken along line II-II' of <FIG>.

<FIG> schematically shows a front surface of the display device <NUM>. In an exemplary embodiment, the display device <NUM> may be quadrangular as a whole, for example. However, the invention is not limited thereto, and in other exemplary embodiments, the display device <NUM> may have various other shapes. In display device <NUM>, a display area DA in which an image is displayed occupies most of the entire region, and a non-display area NA surrounds the display area DA. The display area DA is referred to as a screen, and the non-display area NA is referred to as a bezel. Although the display device <NUM> and the display area are shown with four corners provided angularly, it is not limited thereto, and the corners may be rounded.

<FIG> shows the cross-sectional view of the display device <NUM> shown in <FIG> taken along line II-II' direction, that is, a horizontal direction.

Referring to <FIG>, a light source unit <NUM> is disposed at one side edge of the display device <NUM>. In the display device <NUM>, the vicinity of the edge where the light source unit <NUM> is disposed is referred to as a light-incident portion IA, and the vicinity of the edge where the light source unit <NUM> is not disposed corresponds to the light-incident portion IA and is referred to as a light-facing portion CA. <FIG> shows an exemplary embodiment in which one surface of the optical member <NUM> is the light-incident portion IA and the other surface facing one surface is the light-facing portion CA. However, it is not limited thereto, and the light-incident portion IA may refer to the vicinity of the region where the light source unit <NUM> is disposed, and the light-facing portion CA may refer to the region adjacent to the region facing opposite to the region.

The light source unit <NUM> may be disposed at least one edge of the display device <NUM>, but is not limited thereto.

Referring to <FIG> and <FIG>, the display device <NUM> basically includes a display panel <NUM> and a light unit <NUM>. The display device <NUM> includes frames <NUM> and <NUM> to fix the display panel <NUM> to the light unit <NUM> between the display panel <NUM> and the light unit <NUM>. The display device <NUM> includes a top chassis <NUM> protecting the display panel <NUM> while covering the edge of the display panel <NUM> and preventing the display panel <NUM> from being separated from the light unit <NUM>. The top chassis <NUM> may be disposed only at the edge of the display device <NUM> where the light source unit <NUM> is located, or around all edges of the display device <NUM>. At the back of the light unit <NUM>, a back cover <NUM> covering a driving device, a power supply, etc., for operating the display device <NUM> is disposed.

The display panel <NUM> is a liquid crystal panel including a liquid crystal layer disposed between two transparent substrates <NUM> and <NUM>, on which switching elements, electrodes, color filters, etc., are provided. The display panel <NUM> includes polarization layers <NUM> and <NUM> disposed on respective surfaces of the substrates <NUM> and <NUM>. The display panel <NUM> controls a transmittance of light provided by the light unit <NUM> and passing through the polarizers <NUM> and <NUM>, and the liquid crystal layer under the control of the driving device, to display an image.

The light unit <NUM> supplying the light to the display panel <NUM> is disposed under the display panel <NUM>. The light unit <NUM> includes a bottom chassis <NUM>, a support <NUM>, a bracket <NUM>, the light source unit <NUM> and a reflective sheet <NUM>, an optical member <NUM>, and an optical sheet <NUM>.

The bottom chassis <NUM> is a container in which the constituent elements of the light unit <NUM> are placed or fixed. In an exemplary embodiment, the bottom chassis <NUM> may have a shape such as a rectangular tray as a whole, for example. In an exemplary embodiment, the bottom chassis <NUM> may include a metal material such as aluminum, an aluminum alloy, or a galvanized steel sheet. In an exemplary embodiment, the bottom chassis <NUM> may include a plastic material such as a polycarbonate.

Optical elements including the reflective sheet <NUM>, the optical member <NUM>, and the optical sheet <NUM> are disposed on the bottom chassis <NUM>. The support <NUM> to which the light source unit <NUM> is disposed is provided at the base of the bottom chassis <NUM> in the region adjacent to the light-incident portion IA. The bracket <NUM> supporting the optical member <NUM> is disposed on the bottom chassis <NUM> in the region adjacent to the light-facing portion CA.

The support <NUM> is a kind of heat dissipation part for fixing the light source unit <NUM> and simultaneously transmitting heat generated from the light source unit <NUM> to the bottom chassis <NUM>. The support <NUM> may include a metal material with good thermal conductivity to quickly transfer the heat generated from the light source unit <NUM> to the bottom chassis <NUM> to prevent the light source unit <NUM> from overheating. In an exemplary embodiment, the support <NUM> may be provided by extrusion molding with aluminum, an aluminum alloy, or the like, for example.

The light source unit <NUM> includes a substrate <NUM> disposed to be elongated along the light-incident portion IA, and a light source <NUM> disposed at a predetermined interval therefrom on the substrate <NUM>. In an exemplary embodiment, the substrate <NUM> may be a printed circuit board ("PCB"), particularly a metal core printed circuit board ("MCPCB"), for example. The substrate <NUM> may be fixed to the support <NUM>. The light source <NUM> is electrically connected to wiring of the substrate <NUM>, and receives power to convert electrical energy into light energy to be emitted. The light source <NUM> may be a light emitting diode ("LED") package, and the LED may emit blue light with high color purity. In an exemplary embodiment, the blue light may mean light with a wavelength of about <NUM> nanometers to about <NUM> nanometers, for example. In an exemplary embodiment, an LED may emit blue light with a peak wavelength at about <NUM> nanometer to <NUM> nanometer, for example. The light source <NUM> is disposed so that a light emitting surface faces the optical member <NUM>. In addition to the LED package, a point light source or a line light source may be used as the light source <NUM>.

The optical member <NUM> is used to guide the light emitted from the light source <NUM> and transmit it to the display panel <NUM>. The optical member <NUM> has a function of converting the light having an optical distribution in the form of the point light source or the line light source generated from the light source unit <NUM> into light having an optical distribution in the form of a surface light source, that is, of distributing the light evenly.

The optical member <NUM> also converts the wavelength of the light emitted by the light source <NUM>. The optical member <NUM> may be larger than the display area DA when viewed from the front, so that the light may be provided to an entirety of the display area DA of the display device <NUM>.

The reflective sheet <NUM> may be disposed under the optical member <NUM>, that is, between the optical member <NUM> and the bottom chassis <NUM>. The reflective sheet <NUM> reflects light traveling down the optical member <NUM> and ultimately directs it toward the display panel <NUM>, thereby increasing light efficiency.

The optical sheet <NUM> may be disposed above the optical member <NUM>. The optical sheet <NUM> may include at least one among a diffuser sheet, a prism sheet, and a protecting sheet. The diffuser sheet is used to scatter the light from the optical member <NUM> to make the luminance distribution uniform, that is, to make the surface light source have uniform brightness. The prism sheet adjusts the traveling direction of light diffused by the diffuser sheet so as to be perpendicular to the display panel <NUM>. The protecting sheet may be used to protect a prism of the prism sheet from scratches and the like. The protective sheet may also spread the light and widen the viewing angle that is narrowed by the prism sheet. The optical sheet <NUM> may not include any of the diffuser sheet, the prism sheet, and the protecting sheet, or it may include a plurality of such sheets. The optical sheet <NUM> may further include a reflective polarization sheet capable of increasing luminance efficiency by separating polarization components of light to be transmitted and reflected.

For the frames <NUM> and <NUM> to stably fix the display panel <NUM>, the frame <NUM> disposed adjacent to the light-incident portion IA and the frame <NUM> disposed adjacent to the light-facing portion CA may be structurally different. The display panel <NUM> may be attached to the optical member <NUM> and the bracket <NUM> by adhesion members T1, T2, and T3 such as a double-sided adhesive tape to not be moved.

So far, the overall configuration of the display device <NUM> was described. Now, the optical member <NUM> of the light unit <NUM> in the display device <NUM> according to an exemplary embodiment will be described in detail. Even when there is no particular mention below, the drawings referred to earlier may also be referred to.

<FIG> is a cross-sectional view of an optical member according to an exemplary embodiment. <FIG> shows the light source <NUM> along with the optical member <NUM> to show the relationship of the optical member <NUM> and the light source <NUM>.

Referring to <FIG>, the optical member <NUM> includes a light guide <NUM> as a main configuration to provide the light from the light source <NUM> to the display panel <NUM>. The vicinity of the edge adjacent to the light source <NUM> in the light guide <NUM> is referred to as the light-incident portion, and the vicinity of the edge away from the light source <NUM> facing the light-incident portion is referred to as the light-facing portion.

The optical member <NUM> also includes a low refractive index layer <NUM>, a first capping layer <NUM>, a wavelength conversion layer <NUM>, a second capping layer <NUM>, and an overcoat layer <NUM> that are sequentially stacked on the light guide <NUM>.

The light guide <NUM> guides the path of light emitted from the light source <NUM>. The light guide <NUM> may be a glass light guide. The glass light guide is less deformed by heat and moisture than a plastic light guide including polymethylmethacrylate ("PMMA"), which has a high strength merit.

When using the glass light guide, design freedom of the light unit <NUM> increases, thereby providing a thinner light unit <NUM> and display device <NUM>. In an exemplary embodiment, the glass material of the light guide <NUM> may be a silica-based glass, and may include silicon dioxide (SiO<NUM>), aluminum oxide (Al<NUM>O<NUM>), or the like as a main component, for example. In an exemplary embodiment, the light guide <NUM> may have a thickness of about <NUM> millimeter (mm) to about <NUM>, however it is not limited thereto.

A pattern sheet <NUM> is disposed under the light guide <NUM>, and the low refractive index layer <NUM> having a smaller refractive index than that of the light guide <NUM> is disposed on the light guide <NUM>. The drawings show the exemplary embodiment in which the pattern sheet <NUM> has a simple planar shape, however it is not limited thereto, and the pattern sheet <NUM> may have a shape including a plurality of protrusions and depressions.

The low refractive index layer <NUM> is a metal thin film. In an exemplary embodiment, the low refractive index layer <NUM> may include at least one of silver (Ag), aluminum (Al), a copper-zinc (Cu-Zn) alloy, and copper (Cu). In an exemplary embodiment, the low refractive index layer <NUM> may include silver (Ag) or aluminum (Al) as an example. The metal included in the low refractive index layer <NUM> is not limited to the above-described metal.

In an exemplary embodiment, silver (Ag) for the blue LED having a wavelength of light of about <NUM> nanometer may have a refractive index of about <NUM>, aluminum (Al) may have a refractive index of about <NUM>, the copper-zinc alloy may have a refractive index of about <NUM>, copper (Cu) may have a refractive index of about <NUM>, and gold (Au) may have a refractive index of about <NUM>.

The low refractive index layer <NUM> may be provided through a sputtering process. Adherence of the low refractive index layer <NUM> provided through the sputtering process and the light guide <NUM> may be excellent.

With the low refractive index layer <NUM> of the metal material, since the optical member <NUM> includes a conductive layer, it is possible to prevent static electricity from remaining or accumulating in some regions and to prevent the static electricity from flowing into the display panel.

According to the claimed invention, the thickness of the low refractive index layer <NUM> is about <NUM> angstrom to about <NUM> angstrom, for example. When the thickness of the low refractive index layer <NUM> is less than about <NUM> angstrom, metal flocculation may occur in the process of forming the low refractive index layer <NUM>. In the process of forming the metal layer, it may be difficult to provide the uniform low refractive index layer <NUM> because the metal is aggregated in some regions. When the thickness of the low refractive index layer <NUM> is greater than about <NUM> angstrom, the transmittance of the low refractive index layer <NUM> may be low. In an exemplary embodiment, the light passing through the light guide <NUM> must be provided to the display panel through the low refractive index layer <NUM>, and when the thickness of the low refractive index layer <NUM> is greater than <NUM> Nanometer [<NUM> angström], the light amount provided to the display panel may be reduced because it is difficult to be transmitted to the low refractive index layer <NUM>.

A first interface having the refractive index difference is disposed between the low refractive index layer <NUM> and the light guide <NUM>. The first interface corresponds a light emission surface OS of the light guide <NUM>, and functions as an interface for selectively emitting light L1 guided in the light guide <NUM>. When an incident angle into the light emission surface OS of the light L1 guided in the light guide <NUM> is above the total reflection threshold angle, the light L1 is totally reflected from the first interface and returned in the light guide <NUM>. When the incident angle into the light emission surface OS of the light L2 and L3 guided in the light guide <NUM> is below the total reflection threshold angle, at least some of the light L2 and L3 may pass through the first interface and exit the light guide <NUM>.

The low refractive index layer <NUM> may include silver (Ag) as an example. In an exemplary embodiment, silver (Ag) of the thin film shape may have a refractive index of about <NUM> to about <NUM> for a blue LED having a wavelength of the light of about <NUM> nanometers. In an exemplary embodiment, the refractive index of the light guide <NUM> of the glass material may be about <NUM> to about <NUM>. When the light guide <NUM> and the low refractive index layer <NUM> have the refractive index as described above, the threshold angle of light incident from the light guide <NUM> toward the low refractive index layer <NUM> may be less than about <NUM> degrees (°), and according to an exemplary embodiment, the threshold angle may be less than about <NUM> degrees (°). The total reflection may occur when the incident angle of the light incident from the light guide <NUM> toward the low refractive index layer <NUM> is about <NUM> degrees or more, or for example, the total reflection may occur when the incident angle is about <NUM> degrees or more. Accordingly, most of the light incident on the light guide <NUM> from the light source <NUM> may be totally reflected. As the refractive index difference between the light guide <NUM> and the low refractive index layer <NUM> is increased, the threshold angle may be smaller, and thus the totally reflected light intensity within the light guide <NUM> may be increased.

The totally reflected light in the light emission surface OS is again reflected by the pattern sheet <NUM> or the reflection sheet to be toward the light emission surface OS, and may exit the light guide <NUM> when the incident angle with respect to the light emission surface OS is less than the threshold angle.

In an exemplary embodiment, most of the light traveling from the light source <NUM> towards the light guide <NUM> may be totally reflected. In this way, the totally reflected light may be incident toward the wavelength conversion layer <NUM> and the display panel through the light emission surface OS, so that the emitted light amount and the luminance of the wavelength conversion layer <NUM> may be increased.

In addition, the light leakage phenomenon may occur in the light guide <NUM> adjacent to the light-incident portion, but since the optical member <NUM> according to an exemplary embodiment has the considerably small threshold angle, most of the incident light may be totally reflected, the light leakage phenomenon in the portion may be improved.

An air layer is disposed below the pattern sheet <NUM> and a second interface having the refractive index difference is disposed between the pattern sheet <NUM> and the air layer. The pattern on the pattern sheet <NUM> adjusts the reflection angle of the light L1 guided in the light guide <NUM> so that the light L2 and L3, reflected or scattered by the second interface, for example, is not totally reflected in the first interface and at least part may exit the light guide <NUM>. In another exemplary embodiment, the pattern sheet <NUM> may be omitted, and a lower surface of the light guide <NUM> may be patterned instead.

Accordingly, the light L1 incident on the light incident surface IS of the light guide <NUM> is guided in the light guide <NUM> from the light-incident portion to the light-facing portion, and exits through the entire light-facing surface OS of the light guide <NUM>. Therefore, the light guide <NUM> converts the light having the optical distribution in the form of the point light source or the linear light source generated by the light source <NUM> into the light having the optical distribution in the form of the surface light source. A reflective layer RL may cover a lateral surface of the light-facing portion of the light guide <NUM> so that the light guided in the light guide <NUM> does not pass through the lateral surface of the light-facing portion of the light guide <NUM>.

The first capping layer <NUM> and the wavelength conversion layer <NUM> are sequentially disposed on the low refractive index layer <NUM>.

The first capping layer <NUM> may be disposed between the wavelength conversion layer <NUM> and the low refractive index layer <NUM> to prevent impurities from penetrating into the wavelength conversion layer <NUM>. The first capping layer <NUM> may prevent moisture or oxygen from penetrating into the wavelength conversion layer <NUM>.

In an exemplary embodiment, the first capping layer <NUM> may include at least one among a silicon nitride (SiNx), a silicon oxide (SiOx), an aluminum oxide (AlOx), and a transparent metal oxide. In an exemplary embodiment, the transport metal oxide may include a metal oxide such as an indium-zinc oxide ("IZO"), an indium oxide (InOx), a zinc oxide (ZnOx), a zirconium oxide (ZrOx), an indium-tin oxide ("ITO"), an indium-gallium-zinc oxide ("IGZO"), an indium-tin-zinc oxide ("ITZO"), an indium-tin-gallium-zinc oxide ("ITGZO"), and the like, but it is not limited thereto.

The first capping layer <NUM> may include argon (Ar) according to an exemplary embodiment. The first capping layer <NUM> may be provided through a process subsequent to the process for forming the low refractive index layer <NUM> according to an exemplary embodiment. In an exemplary embodiment, the process atmosphere may include an inactive gas for forming plasma, for example, argon gas. In this argon gas atmosphere, the first capping layer <NUM> provided through the sputtering process may include argon (Ar). However, the invention is not limited thereto, and the type of elements included in the first capping layer <NUM> may vary depending on the type of the inactive gas included in the manufacturing process. That is, the first capping layer <NUM> may include the material corresponding to the inactive gas used in the manufacturing process. The first capping layer <NUM> may be fabricated through the continuous process with the low refractive index layer <NUM>, thus reducing the manufacturing time and cost.

The wavelength conversion layer <NUM> is disposed on the first capping layer <NUM>. The wavelength conversion layer <NUM> may be provided by coating a composition in which quantum dots QD are dispersed in a dispersion medium on the first capping layer <NUM>.

As the dispersion medium, a transparent material with a low absorption rate of light may be used without affecting the wavelength conversion performance of the quantum dots QD, for example epoxy, silicone, polystyrene, acrylate, etc..

In an exemplary embodiment, the quantum dots QD of the wavelength conversion layer <NUM> may include red quantum dots and green quantum dots, for example. In an exemplary embodiment, the red quantum dots convert blue light into red light of a wavelength of about <NUM> nanometers to about <NUM> nanometers, for example. In an exemplary embodiment, the green quantum dots convert blue light into green light of a wavelength of about <NUM> nanometers to about <NUM> nanometers, for example. The blue light, which is not converted to red light or green light, passes through the wavelength conversion layer <NUM> as it is. The optical member <NUM> may provide white light to the display panel <NUM> by mixing blue light, red light, and green light through the wavelength conversion layer <NUM>.

The second capping layer <NUM> is disposed on the wavelength conversion layer <NUM>, and the overcoat layer <NUM> is disposed on the second capping layer <NUM>. The second capping layer <NUM> may include an inorganic material such as a silicon nitride and a silicon oxide, and the overcoat layer <NUM> may include an organic material. The second capping layer <NUM> may prevent the organic material of the wavelength conversion layer <NUM> and the organic material of the overcoat layer <NUM> from being mixed. The second capping layer <NUM> may block moisture or oxygen from penetrating. The overcoat layer <NUM> may protect the optical member <NUM> as a whole. In another exemplary embodiment, at least one of the second capping layer <NUM> and the overcoat layer <NUM> may be omitted.

Next, the low refractive index layer according to an exemplary embodiment is described with reference to <FIG>. <FIG> is a cross-sectional view of an exemplary embodiment of an optical member, <FIG> is a cross-sectional view of an exemplary embodiment of an optical member, and <FIG>, <FIG> and <FIG> are top plan views of exemplary embodiments of a low refractive index layer, respectively. Descriptions of the same and similar constituent elements as the above-mentioned constituent elements are omitted, and differentiating configurations are mainly described.

First, referring to <FIG>, a plurality of openings OP may be defined in the low refractive index layer <NUM> according to an exemplary embodiment. The plurality of openings OP may be defined with a uniform size and interval over the entire region of the low refractive index layer <NUM>. The size and interval may vary depending on the device.

The low refractive index layer <NUM> is made of metal, and for example, may include at least one among silver (Ag), aluminum (Al), a copper-zinc (Cu-Zn) alloy, copper (Cu), and gold (Au).

In an exemplary embodiment, the threshold angle of the light incident toward the low refractive index layer <NUM> from the light guide <NUM> may be about <NUM> degrees (°) or less, for example, about <NUM> degrees (°) or less. The total reflection may occur when the incident angle of the light incident from the light guide <NUM> toward the low refractive index layer <NUM> is about <NUM> degrees or more, for example, the total reflection may occur when the incident angle is about <NUM> degrees or more.

When the low refractive index layer <NUM> includes the metal thin film, most of the light incident from the light source may be totally reflected in the light guide <NUM> according to an exemplary embodiment. In an exemplary embodiment, as a plurality of openings OP is defined in the low refractive index layer <NUM>, some of the light L4 may be emitted through the opening OP without the total reflection. The amount of the light emitted from the light guide <NUM> may thereby be increased.

The first capping layer <NUM> is disposed on the low refractive index layer <NUM>. The first capping layer <NUM> may also be disposed in the opening OP defined in the low refractive index layer <NUM>. The first capping layer <NUM> may have the form of filling a plurality of openings OP.

Next, referring to <FIG>, a plurality of openings OP may be defined in the low refractive index layer <NUM>. In an exemplary embodiment, the distance between the plurality of openings OP may be different. In an exemplary embodiment, as shown in <FIG>, the distance between the openings OP adjacent to the light-incident portion may be greater than the distance between the openings OP adjacent to the light-facing portion, for example. A plurality of openings OP located at the light-incident portion may be relatively small compared to a plurality of openings OP located at the light-facing portion. In other words, the density of the area of the opening OP located in the light-incident portion may be less than the density of the area of the opening OP located in the light-facing portion. Fewer openings OP may be defined in the low refractive index layer <NUM> adjacent to the light-incident portion for the same area than those of the low refractive index layer <NUM> adjacent to the light-facing portion.

The light-incident portion may receive a relatively large amount of incident light compared to the light-facing portion. The light-incident portion is disposed adjacent to the light source <NUM>, and a large amount of light is incident from the light source <NUM>. When the area of the opening OP adjacent to the light-facing portion is large, the amount of light emitted from the region adjacent to the light-facing portion may be greater than the amount of light emitted from the region adjacent to the light-incident portion. However, since light incident from the light source <NUM> at the light-incident portion is large, the amount of light emitted through the low refractive index layer <NUM> may be large even though the light is not emitted through the opening OP. Therefore, the amount of light emitted from the light guide <NUM> may be uniform overall.

Next, referring to <FIG>, a plurality of openings OP may be defined in the low refractive index layer <NUM>. <FIG> shows an exemplary embodiment in which the opening OP is circular in a plan view, but it is not limited thereto, and any shape such as a polygon, a circle, and an ellipse may be used. The specification also shows an exemplary embodiment in which a plurality of openings OP is irregularly arranged, but it is not limited thereto, and in another exemplary embodiment, a plurality of openings OP may be arranged regularly.

Depending on the example, the number of openings OP adjacent to the light-incident portion may be less than the number of openings OP adjacent to the light-facing portion. The number of the openings OP in the same area may be increased towards the light-facing portion in the light-incident portion. In an exemplary embodiment, in the regions A and B with the same area, twelve openings OP may be disposed in the region A, which is disposed adjacent to the light-incident portion, for example. In the exemplary embodiment, thirty six openings OP may be disposed in the region B adjacent to the light-facing portion, for example.

In other words, with respect to the same area, the plane area occupied by a plurality of openings OP in the low refractive index layer <NUM> adjacent to the light-facing portion may be larger than the plane area occupied by the openings OP in the low refractive index layer <NUM> adjacent to the light-incident portion.

The amount of light emitted through a plurality of openings OP adjacent to the light-facing portion may be greater than the amount of light emitted through a plurality of openings OP adjacent to the light-incident portion. However, since the amount of light incident from the light source <NUM> in the light-incident portion is large, the amount of light emitted through the low refractive index layer <NUM> may be large even when the light is not emitted through the opening OP. The amount of light emitted from the entire light guide <NUM> may be uniform.

Next, referring to <FIG>, a plurality of openings OP may be defined in the low refractive index layer <NUM>. <FIG> shows an exemplary embodiment in which the opening OP is circular in a plan view, but it is not limited thereto, and any shape such as a polygon, a circle, and an ellipse may be used.

In the exemplary embodiment, the area of one opening OP adjacent to the light-incident portion and the area of one opening OP adjacent to the light-facing portion may be different. As shown in <FIG>, the plane area of one opening OP adjacent to the light-incident portion may be smaller than the plane area of one opening OP adjacent to the light-facing portion.

When the area of one opening OP adjacent to the light-facing portion is relatively large, the amount of light emitted through the opening OP adjacent to the light-facing portion with respect to the same area A' and B' may be greater than the amount of light emitted through the opening OP adjacent to the incident portion.

However, since the amount of light incident from the light source <NUM> at the light-incident portion is large, the amount of light emitted through the low refractive index layer <NUM> may be large even though the light is not emitted through the opening OP. The amount of light emitted from the entire light guide <NUM> may be uniform.

Next, referring to <FIG>, a plurality of openings OP may be defined in the low refractive index layer <NUM>. The opening OP may have a shape that is continuously connected from the light-incident portion to the light-facing portion. <FIG> shows a preferred embodiment in which the opening OP includes the edge extending in the diagonal direction in a plan view, but it is not limited to this form.

In the exemplary embodiment, the area occupied by the opening OP adjacent to the light-incident portion and the area occupied by the opening OP adjacent to the light-facing portion may be different. As shown in <FIG>, the plane area occupied by the opening OP adjacent to the light-incident portion with respect to the regions A" and B" indicating the same area may be smaller than the plane area occupied by the opening OP adjacent to the light-facing portion. The area occupied by the opening OP may increase towards the light-facing portion in the light-incident portion.

If the area of the opening OP adjacent to the light-facing portion is large, the amount of light emitted through the opening OP adjacent to the light-facing portion is greater than the amount of light emitted through the opening OP located adjacent to the light-light-incident portion. However, since the amount of light incident from the light source <NUM> at the light-incident portion is large, the amount of light emitted through the low refractive index layer <NUM> may be large even though the light is not emitted through the opening OP. The amount of light emitted from the entire light guide <NUM> may be uniform.

Next, an exemplary embodiment and a comparative example are described with reference to <FIG>. <FIG> is a graph of an exemplary embodiment and a comparative example of a light amount, <FIG> is a graph showing an exemplary embodiment of a refractive index of a low refractive index layer, <FIG> is a graph showing an exemplary embodiment of a refractive index of a low refractive index layer, and <FIG> is a graph showing an exemplary embodiment and a comparative example of transmittance.

First, a light emission amount according to the exemplary embodiment and the comparative example is described with reference to <FIG>. The exemplary embodiment relates to an optical member including the low refractive index layer (refractive index of <NUM>) including silver (Ag) as above-described and a light guide (refractive index of <NUM>) of the glass material, Comparative Example <NUM> relates to an optical member including the air layer (refractive index of <NUM>) disposed at the same position as the low refractive index layer and the light guide (refractive index of <NUM>) of the glass material, and Comparative Example <NUM> relates to an optical member including the low refractive index layer (refractive index of <NUM>) including the organic material and the light guide (refractive index of <NUM>) of the glass material.

The threshold angle is about <NUM> degrees in the case of the exemplary embodiment, the threshold angle is about <NUM> degrees in the case of Comparative Example <NUM>, and the threshold angle is about <NUM> degrees in the case of Comparative Example <NUM>. In the case of the illustrative embodiment, the range in which the light is capable of being totally reflected and guided within the light guide is from <NUM> degrees to <NUM> degrees, the range is from <NUM> degrees to <NUM> degrees in the case of Comparative Example <NUM>, and the range is from <NUM> degrees to <NUM> degrees in the case of Comparative Example <NUM>. Since the totally reflected light is reflected by the pattern sheet or the reflection sheet and is finally provided to the wavelength conversion layer, as the light amount of the total reflection is increased, the light amount provided to the wavelength conversion layer may be increased.

The guidable angle range for the exemplary embodiment, Comparative Example <NUM>, and Comparative Example <NUM> is shown in the graph of <FIG>, and it may be confirmed that the amount of the light finally emitted though the total reflection is considerably higher in the exemplary embodiment compared with Comparative Example <NUM> and Comparative Example <NUM>. The case of the exemplary embodiment may provide light of a considerable large amount to the wavelength conversion layer.

Next, referring to <FIG>, in the case of the low refractive index layer including silver (Ag) according to the exemplary embodiment, it may be confirmed that it has a refractive index corresponding to about <NUM> degree in the wavelength range of <NUM> nanometers to <NUM> nanometers. In contrast, in the case of the comparative example including ITO, the refractive index of about <NUM> to about <NUM> appears in the wavelength range of <NUM> Nanometer to <NUM> Nanometers. That is, it is confirmed that the low refractive index layer including the metal such as silver (Ag) has a considerably lower refractive index in the wide wavelength range.

Also, referring to <FIG>, it is confirmed that the low refractive index layer having the thickness of <NUM> Nanometer [<NUM> angström] and including silver (Ag) and the low refractive index layer having the thickness of <NUM> Nanometer [<NUM> angström] and including silver (Ag) have refractive indexes between about <NUM> and <NUM> in the wavelength range of <NUM> nanometers. Like an exemplary embodiment, when the low refractive index layer includes silver (Ag), it is confirmed that it has a considerably lower refractive index. Particularly, it is confirmed that the low refractive index layer has a considerably lower refractive index in the light wavelength range provided by the LED.

Referring to <FIG>, Exemplary Embodiment <NUM> includes the silver (Ag) thin film of a <NUM> angstrom thickness, Exemplary Embodiment <NUM> includes the silver thin film of a <NUM> angstrom thickness, Exemplary Embodiment <NUM> includes the silver thin film of a <NUM> angstrom thickness, Exemplary Embodiment <NUM> includes the silver thin film of a <NUM> angstrom thickness, and Comparative Example <NUM> and Comparative Example <NUM> respectively include the ITO thin film of a <NUM> angstrom thickness.

Claim 1:
A light unit (<NUM>) comprising:
a light source (<NUM>) and an optical member (<NUM>) which transmits and converts light emitted from the light source (<NUM>), the optical member (<NUM>) including:
a light guide (<NUM>) ;
a low refractive index layer (<NUM>) disposed on the light guide (<NUM>);
the low refractive index layer (<NUM>) having a refractive index smaller than a refractive index of the light guide (<NUM>); and
a wavelength conversion layer (<NUM>) disposed on the low refractive index layer (<NUM>) and including quantum dots,
characterized in that
the low refractive index layer (<NUM>) is made of metal and
a thickness of the low refractive index layer (<NUM>) is <NUM> to <NUM>.