Patent ID: 12222601

DETAILED DESCRIPTION

Configurations illustrated in the embodiments and the drawings described in the present specification are only the preferred embodiments of the present disclosure, and thus it is to be understood that various modified examples, which may replace the embodiments and the drawings described in the present specification, are possible when filing the present application.

Also, like reference numerals or symbols denoted in the drawings of the present specification represent members or components that perform the substantially same functions.

The terms used in the present specification are used to describe the embodiments of the present disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention is provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. It will be understood that when the terms “includes,” “comprises,” “including,” and/or “comprising,” when used in this specification, specify the presence of stated features, figures, steps, operations, components, members, or combinations thereof, but do not preclude the presence or addition of one or more other features, figures, steps, operations, components, members, or combinations thereof.

Also, it will be understood that, although the terms including ordinal numbers, such as “first”, “second”, etc., may be used herein to describe various components, these components should not be limited by these terms. These terms are only used to distinguish one component from another. For example, a first component could be termed a second component, and, similarly, a second component could be termed a first component, without departing from the scope of the present disclosure. As used herein, the term “and/or” includes any and all combinations of one or more of associated listed items. Throughout the disclosure, the expression “at least one of a, b or c” indicates only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c. Hereinafter, embodiments of the disclosure will be described in detail with reference to the accompanying drawings.

FIG.1shows an example of an appearance of a display apparatus according to an embodiment of the disclosure. InFIG.1, a display apparatus10may be an apparatus capable of processing image signals received from outside to generate images and visually displaying the images. In the following description, the display apparatus10is assumed to be a television (TV), although not limited thereto. However, the display apparatus10may be implemented as one of various apparatuses, such as a monitor, a portable multimedia apparatus, a portable communication apparatus, etc. That is, a kind of the display apparatus10is not limited as long as the display apparatus10is capable of visually displaying images.

Also, the display apparatus10may be a large format display (LFD) that is installed in an outdoor space, such as the top of building or a bus stop. The outdoor space is not limited to an open-air space, and the display apparatus10according to an embodiment of the disclosure may be installed in any place where many peoples enter, such as a subway station, a shopping mall, a theater, an office, a store, etc., although the place is an indoor space.

The display apparatus10may receive content including a video signal and an audio signal from various content sources, and output video and audio corresponding to the video signal and the audio signal. For example, the display apparatus10may receive content data through a broadcasting reception antenna or a wired cable, receive content data from a content reproducing apparatus, or receive content data from a content providing server of a content provider.

As shown inFIG.1, the display apparatus10may include a main body11and a screen12for displaying an image I. The main body11may form an appearance of the display apparatus10, and components for enabling the display apparatus10to display an image I or perform various functions may be installed inside the main body11. The main body11shown inFIG.1is in the shape of a flat plate, however, a shape of the main body11is not limited to the shape shown inFIG.1. For example, the main body11may be in the shape of a curved plate.

The screen12may be formed on a front side of the main body11and display an image I. For example, the screen12may display a still image or a moving image. Also, the screen12may display a two-dimensional plane image or a three-dimensional stereoscopic image using a user's binocular disparity. The screen12may include a non-emissive panel (for example, a liquid crystal panel) capable of transmitting or blocking light emitted by a backlight unit (BLU), etc.

In the screen12, a plurality of pixels P may be formed, and the image I displayed on the screen12may be formed by light emitted from each of the plurality of pixels P. For example, light emitted from the plurality of pixels P may be combined like mosaic, thereby forming an image Ion the screen12.

Each of the plurality of pixels P may emit light of various brightness and various colors. To emit light of various colors, each of the plurality of pixels P may include a plurality of sub pixels PR, PG, and PB.

The sub pixels PR, PG, and PBmay include a red sub pixel PRcapable of emitting red light, a green sub pixel PGcapable of emitting green light, and a blue sub pixel PBcapable of emitting blue light. For example, the red light may correspond to light of a wavelength range from about 620 nm (nanometer, which is one billionth of a meter) to about 750 nm, the green light may correspond to light of a wavelength range from about 495 nm to about 570 nm, and the blue light may correspond to light of a wavelength range from about 450 nm to about 495 nm.

Each of the plurality of pixels P may emit light of various brightness and various colors by a combination of red light from the red sub pixel PR, green light from the green sub pixel PG, and blue light from the blue sub pixel PB.

FIG.2shows an example of a structure of the display apparatus10according to an embodiment of the disclosure.FIG.3shows an example of a liquid crystal panel included in the display apparatus10according to an embodiment of the disclosure.

As shown inFIG.1, various components for forming an image I on a screen of display apparatus10may be provided inside the main body11.

For example, a backlight unit100being a surface light source, a liquid crystal panel20for transmitting or blocking light emitted from the backlight unit100, a control assembly50for controlling operations of the backlight unit100and the liquid crystal panel20, and a power assembly60for supplying power to the backlight unit100and the liquid crystal panel20may be provided in the main body11. Also, the main body11may include a bezel13, a frame middle mold14, a bottom chassis15, and a rear cover16for supporting the liquid crystal panel20, the backlight unit100, the control assembly50, and the power assembly60.

The backlight unit100may include a point light source for emitting white light. The point light source may include a device for emitting monochromatic light, and a quantum dot cover for converting monochromatic light emitted from the device into white light. For example, the point light source may include a Light Emitting Diode (LED) for emitting blue light, and a quantum dot cover for converting a part of blue light emitted from the light emitting diode into red light and green light. The quantum dot cover may convert a part of blue light into red light and green light by converting a wavelength of the part of the blue light. Thus, blue light emitted from the light emitting diode may be converted into white light by passing through the quantum dot cover.

The backlight unit100may refract, reflect, and scatter light emitted from the point light source to convert the light into uniform surface light. As such, the backlight unit100may emit uniform surface light toward a front direction by refracting, reflecting, and scattering light emitted from the point light source. The backlight unit100will be described in more detail, below.

The liquid crystal panel20may be provided in front of the backlight unit100, and block or transmit light emitted from the backlight unit100to form an image I. A front surface of the liquid crystal panel20may form the above-described screen S of the display apparatus10, and the liquid crystal panel20may form the plurality of pixels P. Each of the plurality of pixels P of the liquid crystal panel20may independently block or transmit light emitted from the backlight unit100. Also, light transmitted by the plurality of pixels P may form an image I that is displayed on the screen S.

For example, as shown inFIG.3, the liquid crystal panel20may include a first polarizing film21, a first transparent substrate22, a pixel electrode23, a thin film transistor24, a liquid crystal layer25, a common electrode26, a color filter27, a second transparent substrate28, and a second polarizing film29.

The first transparent substrate22and the second transparent substrate28may fix and support the pixel electrode23, the thin film transistor24, the liquid crystal layer25, the common electrode26, and the color filter27. The first transparent substrate22and the second transparent substrate28may be made of tempered glass or a transparent resin.

The first polarizing film21and the second polarizing film29may be provided respectively on outer sides of the first transparent substrate22and the second transparent substrate28. The first polarizing film21and the second polarizing film29may transmit certain polarized light and block (reflect or absorb) the other polarized light. For example, the first polarizing film21may transmit polarized light traveling toward a first direction and block (reflect or absorb) the other polarized light. Also, the second polarizing film29may transmit polarized light traveling toward a second direction and block (reflect or absorb) the other polarized light, wherein the second direction may be orthogonal to the first direction. Accordingly, polarized light transmitted by the first polarizing film21may be not directly transmitted through the second polarizing film29.

The color filter27may be provided on an inner side of the second transparent substrate28. The color filter27may include, for example, a red filter27R transmitting red light, a green filter27G transmitting green light, and a blue filter27B transmitting blue light. Also, the red filter27R, the green filter27G, and the blue filter27B may be arranged side by side. An area occupied by the color filter27may correspond to a pixel P described above. An area occupied by the red filter27R may correspond to a red sub pixel PR, an area occupied by the green filter27G may correspond to a green sub pixel PG, and an area occupied by the blue filter27B may correspond to a blue sub pixel PB.

The pixel electrode23may be provided on an inner side of the first transparent substrate22, and the common electrode26may be provided on the inner side of the second transparent substrate28. The pixel electrode23and the common electrode26may be made of a metal material carrying electricity, and form an electric field for changing an arrangement of liquid crystal molecules115aconfiguring the liquid crystal layer25which will be described below.

On the inner surface of the first transparent substrate22, the thin film transistor24may be positioned. The thin film transistor24may be turned on (closed) or turned off (opened) by image data provided from the panel driver30. Also, according to turning-on (closing) or turning-off (opening) of the thin film transistor24, an electric field may be formed or removed between the pixel electrode23and the common electrode26.

The liquid crystal layer25may be formed between the pixel electrode23and the common electrode26, and the liquid crystal layer25may be filled with the liquid crystal molecules25a. Liquid crystal is in an intermediate state between a solid (crystal) state and a liquid state. The liquid crystal shows an optical property according to a change in electric field. For example, the direction of the molecular arrangement of liquid crystal changes according to a change in electric field. As a result, the optical property of the liquid crystal layer25may change according to the presence or absence of an electric field passing through the liquid crystal layer25. For example, the liquid crystal layer25may rotate a polarizing direction of light with respect to an optical axis according to presence/absence of an electric field. Thereby, a polarizing direction of polarized light passed through the first polarizing film21may rotate while the polarized light passes through the liquid crystal layer25, and then the resultant polarized light may pass through the second polarizing film29.

At one edge of the liquid crystal panel20, a cable20afor transmitting image data to the liquid crystal panel20, and a Display Driver Integrated circuit (DDI) (hereinafter, referred to as a ‘panel driver’30) for processing digital image data and outputting an analog image signal may be provided.

The cable20amay electrically connect the control assembly50and the power assembly60with the panel driver30, and also electrically connect the panel driver30with the liquid crystal panel20. The cable20amay include a flexible flat cable or a film cable.

The panel driver30may receive image data and power from the control assembly50and the power assembly60through the cable20a. Also, the panel driver30may provide image data and driving current to the liquid crystal panel20through the cable20a.

Also, the cable20aand the panel driver30may be integrated into one body and implemented as a film cable, a Chip On Film (COF), a Tape Carrier Package (TCP), etc. In other words, the panel driver30may be positioned on the cable20a, although not limited thereto. However, the panel driver30may be positioned on the liquid crystal panel20.

The control assembly50may include a control circuit for controlling operations of the liquid crystal panel20and the backlight unit100. For example, the control circuit may process a video signal and/or an audio signal received from an external content source. The control circuit may transmit image data to the liquid crystal panel20, and transmit dimming data to the backlight unit100.

The power assembly60may include a power circuit for supplying power to the liquid crystal panel20and the backlight unit100. The power circuit may supply power to the control assembly50, the backlight unit199, and the liquid crystal panel20.

The control assembly50and the power assembly60may be implemented with a printed circuit board and various kinds of circuits mounted on the printed circuit board. For example, the power circuit may include a capacitor, a coil, a resistor device, a processor, and a power circuit board on which the capacitor, the coil, the resistor device, and the processor are mounted. Also, the control circuit may include a memory, a processor, and a control circuit board on which the memory and the processor are mounted.

FIG.4shows an example of a backlight unit included in a display apparatus according to an embodiment of the disclosure.FIG.5schematically shows an example of a light source included in a backlight unit according to an embodiment of the disclosure.

As shown inFIG.4, the backlight unit100may include a light source module110for generating light, a diffuser plate130for uniformly diffusing light, and an optical sheet140for improving brightness of exit light. The light source module110may include a plurality of light sources111for emitting light, and a substrate112for supporting and fixing the plurality of light sources111.

The plurality of light sources111may be arranged in a preset pattern to emit light with uniform brightness. The plurality of light sources111may be arranged such that distances between each light source and the neighboring light sources are the same.

For example, as shown inFIG.4, the plurality of light sources111may be arranged in regular rows and columns. Accordingly, the plurality of light sources111may be arranged such that four neighboring light sources form substantially a square. Also, any one light source may be adjacent to four light sources, and distances between the light source and the four adjacent light sources may be substantially the same.

The plurality of light sources111may be arranged such that three neighboring light sources form substantially an equilateral triangle. In this case, one light source may be adjacent to six light sources. Also, distances between the light source and the six adjacent light sources may be substantially the same.

However, an arrangement of the plurality of light sources111is not limited to the above-described arrangement, and the plurality of light sources111may be arranged in various ways as long as the light sources111emit light with uniform brightness. Each light source111may adopt a device capable of emitting, upon receiving power, monochromatic light (light having a certain range of wavelength or light having a single peak wavelength, for example, blue light) in various directions.

As shown inFIG.5, each of the plurality of light sources111may include a light emitting diode190, a quantum dot cover160, a refractive cover170, and a reflector180. The light emitting diode190may be attached directly to the substrate112by a Chip On Board (COB) method. For example, a light source111may include a light emitting diode190formed by attaching a light emitting diode chip or a light emitting diode die directly to the substrate112without separate packaging.

The light emitting diode190may be manufactured as a flip chip type. The flip chip type of the light emitting diode190may be formed by welding, upon attaching a light emitting diode being a semiconductor device to the substrate112, an electrode pattern of a semiconductor device as it is to the substrate112without using a middle medium, such as a metal lead (wire) or a Ball Grid Array (BGA). As such, by using neither a metal lead (wire) nor a ball grid array, the light source111including the flip chip type of the light emitting diode190may be miniaturized.

The light emitting diode190may emit monochromatic light. According to an embodiment of the disclosure, the light emitting diode190may emit blue light. The blue light emitted from the light emitting diode190may be converted into white light by passing through the quantum dot cover160, although not limited thereto. However, the light emitting diode190may emit red light or green light.

The quantum dot cover160may cover the light emitting diode190. The quantum dot cover160may prevent or suppress the light emitting diodes190from being damaged by a mechanical action from outside and/or by a chemical action.

The quantum dot cover160may convert a wavelength of monochromatic light emitted from the light emitting diode190. The quantum dot cover160may convert monochromatic light emitted from the light emitting diode190into white light by converting a wavelength of the monochromatic light.

For example, the light emitting diode190may emit blue light, and the quantum dot cover160may convert a part of the blue light into red light and green light by converting a wavelength of the part of the blue light. Because a part of blue light emitted from the light emitting diode190is converted into red light and green light by passing through the quantum dot cover160, light emitted from the quantum dot cover160may become white light. Accordingly, the light source module110according to the disclosure may include a light source111that emits white light.

According to an embodiment of the disclosure, the quantum dot cover160may be formed by dispensing or jetting a liquid quantum dot resin and then hardening the liquid quantum dot resin. The quantum dot cover160may be formed by dispensing or jetting and then only hardening without another process. In other words, the quantum dot cover160may be considered to be self-formed.

The quantum dot cover160may surround an upper surface and four side surfaces of the light emitting diode190. The quantum dot cover160may be formed by dispensing or jetting a liquid quantum dot resin to cover the upper surface and four side surfaces of the light emitting diode190and then hardening the liquid quantum dot resin.

The refractive cover170may cover the quantum dot cover160. The refractive cover170may prevent or suppress the quantum dot cover160from being damaged by a mechanical action from outside and/or by a chemical action.

According to an embodiment of the disclosure, the refractive cover170may be in a shape of a dome having a recessed portion at a center. More specifically, the refractive cover170may be provided as a rotational symmetry shape of which a lower surface is in a shape of a circle and which has a maximum height h (see e.g.,FIG.7) at a point P spaced a certain distance in a horizontal direction from a center of the lower surface. A portion of the refractive cover170around the point P (see e.g.,FIG.7) having the maximum height h may be upwardly convex with respect to a radial direction of the refractive cover170.

The refractive cover170may be made of a silicon or epoxy resin. For example, the refractive cover170may be formed by dispensing a molten silicon or epoxy resin in a liquid state on the quantum dot cover160through a nozzle, etc. and then hardening the dispensed silicon or epoxy resin.

According to an embodiment of the disclosure, the refractive cover170may be formed by dispensing a liquid transparent material from a plurality of points spaced from each other and then hardening the dispensed liquid transparent material. The refractive cover170may be formed only by dispensing and hardening without performing another process. In other words, the refractive cover170may be considered to be self-formed.

The refractive cover170may be optically transparent or translucent. Light emitted from the light emitting diode190may be discharged to outside by passing through the quantum dot cover160and the refractive cover170.

At this time, the refractive cover170may refract the light, like a lens. For example, light emitted from the light emitting diode190and discharged to outside of the quantum dot cover160may be dispersed by being refracted by the refractive cover170.

As such, the refractive cover170may cover the quantum dot cover160to disperse light discharged to the outside of the quantum dot cover160.

The substrate112may fix the plurality of light sources111, thus the plurality of light sources111does not change their positions. Also, the substrate112may supply power required for the light sources111to emit light to the light sources111.

The substrate112may fix the plurality of light sources111. The substrate112may be configured as a synthetic resin, tempered glass, or a printed circuit board (PCB) on which a conductive power supply line for supplying power to the light sources111is formed.

A lower reflector113may be provided on an upper surface of the substrate112. The lower reflector113may include a Photo Solder Resist (PSR) coated on the upper surface of the substrate112. The lower reflector113may reflect light reflected toward the lower reflector113from the reflector180, which will be described below.

A plurality of light emitting diodes190may be arranged on the upper surface of the substrate112to form an array. Accordingly, a plurality of quantum dot covers160may be provided to respectively correspond to the plurality of light emitting diodes190. Likewise, a plurality of refractive covers170may be provided to respectively correspond to the plurality of quantum dot covers160.

According to an embodiment of the disclosure, the reflector180may be provided in the recessed portion formed at the center of the refractive cover170. The recessed portion may be formed at the center of the refractive cover170in such a way as to be recessed toward the quantum dot cover160. That is, as illustrated, e.g., inFIG.7, the recessed portion's contour of the refractive cover170is substantially similar to a contour of the quantum dot cover160. InFIG.7, from the reflector113, the recessed portion's contour of the refractive cover170is positioned higher than the contour of the quantum dot cover160.

The reflector180may reflect a part of light emitted from the light emitting diode190, passed through the quantum dot cover160and the refractive cover170, and then entered the reflector180. The reflector180may be positioned above the quantum dot cover160. The reflector180may be spaced a certain distance from the quantum dot cover160in a vertical direction. The distance between the reflector180and the quantum dot cover160may change according to one or more embodiments of the disclosure. An area of an upper surface or a lower surface of the reflector180may be larger than an area of a lower surface of the quantum dot cover160. A diameter of the upper surface of the reflector180may be greater than a diameter of the lower surface. In other words, the diameter of the lower surface of the reflector180may be smaller than the diameter of the upper surface. In one embodiment, the reflector180may be formed by dispensing a liquid reflective material in the recessed portion of the refractive cover170and then hardening the dispensed liquid reflective material. Accordingly, a shape of the reflector180may be defined by a shape of the recessed portion of the refractive cover170. According to one or more embodiments of the disclosure, the shape of the recessed portion of the refractive cover170may change to change the shape of the reflector180within a certain range.

According to an embodiment of the disclosure, unlikeFIG.4, a substrate extending in one direction to have a bar shape may be provided. In this case, a plurality of light emitting diodes may be arranged at intervals in the extension direction of the substrate to form an array. A plurality of substrates each having a bar shape may be provided. The plurality of substrates may be spaced from each other along a direction that is perpendicular to the extension direction of the substrates. For example, the substrates each having the bar shape may extend along the horizontal direction, while being spaced from each other along the vertical direction.

The diffuser plate130may be provided in front of the light source module110. The diffuser plate130may uniformly disperse light emitted from the light sources111of the light source module110.

The diffuser plate130may diffuse light emitted from the plurality of light sources111within the diffuser plate130to reduce brightness non-uniformity caused by the plurality of light sources111. In other words, the diffuser plate130may emit relatively uniform light from a front surface by diffusing non-uniform light emitted from the plurality of light sources111.

The optical sheet140may include various sheets for improving brightness and uniformity of brightness. For example, the optical sheet140may include a light conversion sheet141, a diffuser sheet142, a prism sheet143, and a reflective polarizing sheet144.

However, the optical sheet140is not limited to the sheets or films shown inFIG.4, and may include various other sheets or films such as a protective sheet.

FIG.6shows an example of a light emitting diode included in a backlight unit according to an embodiment of the disclosure. InFIG.6, the light emitting diode190may include a transparent substrate195, an n-type semiconductor layer193, and a p-type semiconductor layer192. Also, a multi quantum wells layer194may be formed between the n-type semiconductor layer193and the p-type semiconductor layer192.

The transparent substrate195may be a base of a pn junction capable of emitting light. The transparent substrate195may include, for example, sapphire (Al2O3) having a crystal structure that is similar to those of the n-type semiconductor layer193and the p-type semiconductor layer192.

A pn junction may be implemented by connecting the n-type semiconductor layer193with the p-type semiconductor layer192. A depletion region may be formed between the n-type semiconductor layer193and the p-type semiconductor layer192. In the depletion region, electrons of the n-type semiconductor layer193may be recombined with holes of the p-type semiconductor layer192. By the recombination of the electrons with the holes, light may be emitted.

The n-type semiconductor layer193may include, for example, n-type gallium nitride (GaN). The p-type semiconductor layer192may also include, for example, p-type GaN. An energy band gap of GaN may be 3.4 electronvolt (eV) capable of emitting light having a wavelength that is shorter than about 400 nm. Accordingly, in the junction of the n-type semiconductor layer193and the p-type semiconductor layer192, deep blue light or ultraviolet light may be emitted.

The n-type semiconductor layer193and the p-type semiconductor layer192are not limited to gallium nitride, and may be formed with various semiconductor materials according to desired light.

A first electrode191aof the light emitting diode190may be in electrical contact with the p-type semiconductor layer192, and the second electrode191bmay be in electrical contact with the n-type semiconductor layer193. The first electrode191aand the second electrode191bmay function as electrodes, as well as functioning as reflectors for reflecting light.

According to application of a voltage to the light emitting diode190, holes may be supplied to the p-type semiconductor layer192through the first electrode191a, and electrons may be supplied to the n-type semiconductor layer193through the second electrode191b. The electrons and holes may be recombined in the depletion region formed between the p-type semiconductor layer192and the n-type semiconductor layer193. At this time, during the recombination of the electrons and holes, energy (for example, kinetic energy and potential energy) of the electrons and holes may be converted into optical energy. In other words, according to recombination of electrons and holes, light may be emitted.

At this time, an energy band gap of the multi quantum wells layer194may be smaller than an energy band gap of the p-type semiconductor layer192and/or the n-type semiconductor layer193. Accordingly, the holes and electrons may be captured by the multi quantum wells layer194.

The holes and electrons captured by the multi quantum wells layer194may be easily recombined in the multi quantum wells layer194. Accordingly, photogeneration efficiency of the light emitting diode190may be improved.

The multi quantum wells layer194may emit light having a wavelength corresponding to the energy band gap of the multi quantum wells layer194. For example, the multi quantum wells layer194may emit blue light having a wavelength range from 420 nm to 480 nm. As such, the multi quantum wells layer194may correspond to a light-emitting layer for emitting blue light.

Light generated by recombination of electrons and holes may be emitted in all directions, not in a specific direction, as shown inFIG.6. However, in a case of light emitted from a surface such as the multi quantum wells layer194, light emitted in a direction that is perpendicular to the light-emitting surface may have greatest intensity and light emitted in a direction that is parallel to the light-emitting surface may have smallest intensity.

A first reflector196may be provided on an outer side (an upper side) of the transparent substrate195inFIG.6. That is, the first reflector196may be positioned above the multi quantum wells layer194. Also, a second reflector197may be provided on an outer side (a lower side of the p-type semiconductor layer192inFIG.6of the p-type semiconductor layer192. As such, the transparent substrate195, the n-type semiconductor layer193, the multi quantum wells layer194, and the p-type semiconductor layer192may be positioned between the first reflector196and the second reflector197.

Each of the first reflector196and the second reflector197may reflect a part of incident light, and transmit the other part of the incident light. For example, the first reflector196and the second reflector197may reflect light having a wavelength included in a certain wavelength range, and transmit light having a wavelength deviating from the certain wavelength range. For example, the first reflector196and the second reflector197may reflect blue light having a wavelength range from 420 nm to 480 nm, emitted from the multi quantum wells layer194.

Also, the first reflector196and the second reflector197may reflect incident light having a certain incident angle, and transmit light deviating from the certain incident angle. As such, each of the first reflector196and the second reflector197may be a Distributed Bragg Reflector (DBR) layer formed by stacking materials having different refractive indexes to have different reflectance according to incident angles.

For example, the first reflector196may reflect incident light with a small incident angle, and transmit incident light with a great incident angle. Also, the second reflector197may reflect or transmit incident light with a small incident angle, and reflect incident light with a great incident angle. The incident light may be blue light having a wavelength from 420 nm to 480 nm.

FIG.7shows an example of a cross section taken along line A-A ofFIG.5. InFIG.7, a part of blue light emitted from the light emitting diode190may be converted into red light and green light by passing the quantum dot cover160. However, although blue light emitted from the light emitting diode190passes through the quantum dot cover160, intensity of the blue light may be still greater than intensity of the converted red light and green light. In this case, because the blue light, red light, and green light have different intensity, light passed through the quantum dot cover160may not become white light.

In a relevant technique of using a quantum dot resin to obtain white light from monochromatic light emitted from a light emitting diode, a relatively large amount of a quantum dot resin has been used. The reason may be because a large amount of a quantum dot resin is required to form a quantum dot layer having a sufficient thickness.

According to an embodiment of the disclosure, a part of light passed through the quantum dot cover160and then emitted to the outside of the quantum dot cover160may be reflected backward by the reflector180, and the part of the light reflected backward may be again reflected forward by the lower reflector113. In other words, light emitted from the light emitting diode190may be regenerated by the reflector180and the lower reflector113. Through the regeneration process, light emitted from the light emitting diode190may pass through the quantum dot cover160several times. As light passes through the quantum dot cover160several times, intensity of blue light may decrease relatively, while intensity of red light and green light may increase. Accordingly, deviations in intensity between blue light, red light, and green light may be reduced. By reducing deviations in intensity between blue light, red light, and green light, desired white light may be obtained. Also, because the quantum dot cover160is formed by dispensing a liquid quantum dot resin on a minimum area to cap the light emitting diode190, an amount of use of a quantum dot resin may be significantly reduced compared to the relevant technique.

According to an embodiment of the disclosure, a lower surface181of the reflector180may have an upwardly convex shape. The reflector180may be formed by dispensing a liquid reflective material on the refractive cover170and then hardening the dispensed liquid reflective material. The liquid reflective material may include, for example, silicon dioxide (SiO2) or silver (Ag).

According to an embodiment of the disclosure, for the lower surface181of the reflector180to have the upwardly convex shape, the recessed portion provided at the center of the refractive cover170may have an upwardly convex shape at a center portion. That is, the recessed portion may be more recessed toward the substrate112than the point P having the maximum height h in the refractive cover170, and the center portion of the recessed portion may have an upwardly convex shape. In one embodiment, an upper surface of the reflector180may be flat. That is, the upper surface of the reflector180may be a circular flat surface.

A linear distance between the center portion of the lower surface181of the reflector180and a center portion of an upper surface of the quantum dot cover160may be d1. By changing a distance between the center portion of the lower surface181of the reflector180and the center portion of the upper surface of the quantum dot cover160, a beam angle profile of the light source111may change, which will be described below. More specifically, a short distance between the lower surface181of the reflector180and the upper surface of the quantum dot cover160may increase a beam angle of the light source111. In contrast, a long distance between the lower surface181of the reflector180and the upper surface of the quantum dot cover160may decrease a beam angle of the light source111.

Hereinafter, a radius of the lower surface of the quantum dot cover160may be referred to as Lq. A horizontal distance from a center of the light emitting diode190to an outermost point of the reflector180to which a marginal ray passing through the refractive cover170is tangent may be referred to as Lr. A vertical distance between the outermost point of the reflector180to which a marginal ray is tangent and the lower reflector113may be referred to as H1. A radius of a lower surface of the refractive cover170may be referred to as Ls. Also, an angle between the marginal ray and the lower reflector113may be referred to as θm1. θm1may be expressed as θm1=tan−1(H1/Lr)

According to an embodiment of the disclosure, the refractive cover170and the reflector180may be formed such that 10°<θm1<70°. For the light source111to obtain an optical profile having a great beam angle, 10°<θm1<70°.

Also, for the reflector180to reflect light emitted upward from the quantum dot cover160, Lr may be greater than Lq (Lr>Lq). By the structure, light emitted with a greater angle than θm1from the quantum dot cover160may be reflected backward by the reflector180, and the light reflected by the reflector180may be again reflected forward by the lower reflector113.

Also, the diameter of the lower surface181of the reflector180may be greater than the diameter of the lower surface of the quantum dot cover160. By the structure, the reflector180may reflect light emitted upward from the quantum dot cover160, backward, at the lower surface.

FIG.8shows an example of an optical profile emitted from a light source according to an embodiment of the disclosure. InFIG.8, the light source111according to an embodiment of the disclosure may have an optical profile being substantially in a shape of a bat wing. In other words, the light source111may have an optical profile of a great beam angle. Because the reflector180is provided above the light emitting diode190and the quantum dot cover160, light emitted upward from the light emitting diode190may be reflected downward by the reflector180, and the light reflected downward may be again reflected by the lower reflector113. Thereby, the light may exit the refractive cover170. Through the above-described process, light exited the refractive cover170may have an optical profile of a great beam angle.

As illustrated inFIG.8, the light emitting diode190may have an optical profile being substantially in a shape of a bat wing. The optical profile being substantially in the shape of the bat wing may be an optical profile in which intensity of light emitted in an oblique direction (for example, a direction having an angle range (peak ½) of about 30 degrees to about 70 degrees from a vertical axis being perpendicular to the substrate112) from the light source111is greater than intensity of light emitted in a direction being perpendicular to the substrate112from the light source111.

The optical profile shown inFIG.8may be an example of an optical profile of the light source111, and the light source111may have an optical profile that is similar to the optical profile ofFIG.8, according to one or more embodiments of the disclosure.

Due to the light source111having the optical profile being in the shape of the bat wing, a number of the light emitting diodes190included in the display apparatus10may be reduced.

To improve image quality of the display apparatus10, the backlight unit100may need to emit surface light having uniform brightness. For example, according to a reduction of the number of light emitting diodes being point light sources, a deviation between brightness of an area where the light emitting diodes exist and brightness of an area (an area between light emitting diodes) where no light emitting diode exists may increase. In other words, according to a reduction of the number of light emitting diodes being point light sources, brightness uniformity of surface light emitted from the backlight unit100may deteriorate.

In this case, by using the light source111having the optical profile being in the shape of the bat wing, a deviation between brightness of an area where each light source111exists and brightness of an area between two neighboring light sources may be reduced. Accordingly, the number of the light emitting diodes190may be reduced.

Furthermore, in the display apparatus10having a small thickness, an optical distance (OD) by which light emitted from light emitting diodes being point light sources is diffused to surface light may be short. Accordingly, brightness uniformity of surface light emitted from the backlight unit100may deteriorate. To maintain brightness uniformity, the number of light emitting diodes may increase.

By including the light emitting diode190, the quantum dot cover160, the refractive cover170, and the reflector180, the light source111may have an optical profile being in a shape of a bat wing, and because the light source111has an optical profile being in a shape of a bat wing, an increase of the number of the light sources111may be reduced.

FIG.9shows emission spectrums according to presence or absence of a reflector in a light source of a backlight unit according to an embodiment of the disclosure. InFIG.9, the light source111according to an embodiment of the disclosure may have a different characteristic of an emission spectrum by including a reflector.

More specifically, in a case in which the light source111includes no reflector180, intensity of blue light in light emitted from the light source111may be relatively greater than intensity of red light and green light in the light. Because the intensity of the blue light is greater than the intensity of the green light and the intensity of the green light is greater than the intensity of the red light, imbalance between the blue light, the green light, and the red light may be relatively great. Due to such imbalance, the light source may not emit white light. To overcome the imbalance, a relatively large amount of a quantum dot resin may be required.

The light source111according to an embodiment of the disclosure may achieve balance between blue light, green light, and red light by including the reflector180. Specifically, intensity of green light may become similar to intensity of blue light. Also, a difference between intensity of blue light and intensity of red light may be reduced, and likewise, a difference between intensity of green light and intensity of red light may be reduced. As such, because differences in intensity between blue light, green light, and red light are reduced, the light source111may emit white light with a relatively small amount of a quantum dot resin. That is, an amount of use of a quantum dot resin having high cost may be reduced. Accordingly, production cost of the light source111may be reduced, and furthermore, production cost of the display apparatus10may also be reduced.

FIG.10shows another example of a cross section taken along line A-A ofFIG.5. InFIG.10, in the light source111according to an embodiment of the disclosure, a distance between the center of the lower surface181of the reflector180and a center of the upper surface of the quantum dot cover160may be d2. d2 may be smaller than d1 shown inFIG.7. That is, d2<d1 may be satisfied. A vertical distance H2 between the reflector180to which a marginal ray is tangent and the lower reflector113may be smaller than H1. That is, H2<H1 may be satisfied.

As shown inFIG.10, as a distance between the reflector180and the quantum dot cover160is shortened, an angle θm2between the reflector113and a marginal ray passing through the refractive cover170from a center of the light emitting diode190may be reduced. That is, in a case in which d2<d1, θm2<θm1. At a small angle θm2, a beam angle of the light source111may be greater than at the angle θm1. That is, in the case in which a distance between the reflector180and the quantum dot cover160is short, an optical profile of a relatively great beam angle may be obtained.

Although d2 is smaller than d1, 10°<θm2<70° may be satisfied. That is, 10°<tan−1(H2/Lr)<70° may be satisfied.

As such, by adjusting the distance between the lower surface181of the reflector180and the quantum dot cover160, a beam angle of the light source111may be adjusted.

FIG.11shows another example of a cross section taken along line A-A ofFIG.5.FIG.12shows light paths in a lower surface of a reflector shown inFIG.11. InFIGS.11and12, in the light sources111according to an embodiment of the disclosure, a glass beads array282may be provided on a lower surface281of a reflector280. The lower surface281of the reflector280may be flat. The lower surface281of the reflector280may be a circular flat surface. A center portion of a refractive cover270may be recessed to correspond to the reflector280. A vertical distance between the lower reflector113and the reflector280to which a marginal ray is tangent may be H (H>H1). According to an embodiment of the disclosure, 10°<tan−1(H/Lr)<70° may be satisfied. That is, 10°<θm<70° may be satisfied.

InFIG.11, a diameter of the lower surface281of the reflector280may be greater than the diameter of the lower surface of the quantum dot cover160. By the structure, the reflector280may reflect light emitted upward from the quantum dot cover160, backward, at the lower surface281.

InFIG.12, the light source111according to an embodiment of the disclosure may include the glass beads array282as a retro-reflector on the lower surface281of the reflector280. According to a characteristic of the retro-reflector, light entered the glass beads array282may be reflected with the same exit angle as an incident angle. The light source111according to an embodiment of the disclosure may reflect light entered the reflector280from the light emitting diode190via the quantum dot cover160to the lower reflector113by including the glass beads array282on the lower surface281of the reflector280. As described above, light reflected to the lower reflector113may be again reflected forward by the lower reflector113and, accordingly, the light source111may obtain an optical profile of a great beam angle.

FIG.13shows another example of a cross section taken along line A-A ofFIG.5.FIG.14shows a microprism array provided in a lower surface of a reflector shown inFIG.13.FIG.15schematically shows light paths in the lower surface of the reflector shown inFIG.13.

InFIGS.13and14, in the light source111according to an embodiment of the disclosure, a microprism array381may be provided on a lower surface of a reflector380. The lower surface of the reflector380may be flat. The lower surface of the reflector380may be a circular flat surface. A center portion of a refractive cover370may be recessed to correspond to the reflector380. A vertical distance between the lower reflector113and the reflector380to which a marginal ray is tangent may be H. H>H1. The microprism array381may include a regular tetrahedral array.

InFIG.13, a diameter of the lower surface of the reflector380may be greater than the diameter of the lower surface of the quantum dot cover160. By the structure, the reflector380may reflect light emitted upward from the quantum dot cover160, backward, at the lower surface.

InFIGS.14and15, the light source111according to an embodiment of the disclosure may include the microprism array381as a retro-reflector on the lower surface of the reflector380. According to a characteristic of the retro-reflector, light entered the microprism array381may be reflected with the same exit angle as an incident angle. The light source111according to an embodiment of the disclosure may reflect light entered the reflector380from the light emitting diode190via the quantum dot cover160to the lower reflector113by including the microprism array381on the lower surface of the reflector380. As described above, light reflected to the lower reflector113may be again reflected forward by the lower reflector113and accordingly, the light source111may obtain an optical profile of a great beam angle.

FIG.16schematically shows an example of a method for manufacturing a light source of a backlight unit according to an embodiment of the disclosure. Hereinafter, an example of a method for manufacturing a backlight unit according to an embodiment of the disclosure will be described with reference toFIG.16. InFIG.16, the light source111according to an embodiment of the disclosure may be manufactured by an injection molding process.

More specifically, the light emitting diode190may be mounted on the substrate112by the COB method, an upper mold B may be positioned on the quantum dot cover160dispensed and hardened to cover the light emitting diode190, and a lower mold B1may be positioned below the substrate112.

The upper mold B2may include a preset groove r for defining a shape of the refractive cover170. The preset groove r may correspond to a location of the light emitting diode190and the quantum dot cover160.

According to an embodiment of the disclosure, the substrate112, the light emitting diode190, and the quantum dot cover160may be positioned on the lower mold B1, the upper mold B2may move toward the lower mold B1to close a cavity, and then, a liquid transparent material for forming the refractive cover170may be injected through a flow path p1connected with the groove r. The transparent material injected into the groove r through the flow path p1may be hardened to form the refractive cover170. By the process, the refractive cover170may be formed on the substrate112to directly cover the quantum dot cover160, without being subject to a process of bonding the refractive cover170onto the substrate112.

According to an embodiment of the disclosure, the reflector180may be formed by forming the refractive cover170on the substrate112through the above-described injection molding process without a bonding operation, dispensing a liquid reflective material on the refractive cover170, and then hardening the liquid reflective material. The liquid reflective material may include, for example, silicon dioxide (SiO2) or silver (Ag). However, the reflector180may be formed by a double injection method, together with the refractive cover170.

FIG.17schematically shows another example of a method for manufacturing a light source of a backlight unit according to an embodiment of the disclosure. InFIG.17, the light source111may be formed by mounting the light emitting diode190on the substrate112by the COB method, dispensing and hardening a liquid quantum dot resin to form the refractive cover170, and bonding the refractive cover170and the reflector180manufactured separately on the substrate112.

That is, the light source111may be manufactured by manufacturing a plurality of refractive covers170and a plurality of reflectors180separately and bonding the refractive covers170and the reflectors180on the substrate112to respectively correspond to the plurality of light emitting diodes190and the plurality of quantum dot covers160.

The refractive cover170and the reflector180may be manufactured by various methods. For example, the refractive cover170and the reflector180may be manufactured by a single process through a double injection method, or by first manufacturing a refractive cover through injection molding and then dispensing and hardening a liquid reflective material.

FIG.18schematically shows a method for forming a quantum dot cover in a method for manufacturing a light source of a backlight unit according to an embodiment of the disclosure.FIG.19schematically shows a method for forming a refractive cover in a method for manufacturing a light source of a backlight unit according to an embodiment of the disclosure.FIG.20schematically shows a method for forming a reflector in a method for manufacturing a light source of a backlight unit according to an embodiment of the disclosure.

A method for manufacturing the light source111according to an embodiment of the disclosure will be described with reference toFIGS.18to20. InFIG.18, the light emitting diode190may be mounted on the substrate112by the COB method, and then, a liquid quantum dot resin T1may be dispensed through a first dispenser J1to cover the light emitting diode190. The first dispenser J1may be positioned above the light emitting diode190to dispense the quantum dot resin T1on the light emitting diode190. The quantum dot resin T1may be dispensed in a liquid state and then hardened to form the quantum dot cover160.

InFIG.19, each of a second dispenser J2and a plurality of third dispensers J3may dispense a liquid transparent material T2. The third dispensers J3may be spaced a preset distance from the second dispenser J2in the horizontal direction. The second dispenser J2may be positioned between the plurality of third dispensers J3.

Each of the second dispenser J2and the plurality of third dispensers J3may dispense the liquid transparent material T2, and the liquid transparent material dispensed by the second dispenser J2and the plurality of third dispensers J3may be hardened to form the refractive cover170.

A shape of the refractive cover170may be defined according to an amount of the transparent material T2dispensed by each of the second dispenser J2and the plurality of third dispensers J3, the distance between the second dispenser J2and the plurality of third dispensers J3, and thixotropic of the transparent material T2.

InFIG.20, a fourth dispenser J4may dispense a liquid reflective material T3in the recessed portion formed in the center portion of the refractive cover170, and then the dispensed reflective material may be hardened to form the reflector180.

As shown inFIGS.18to20, the quantum dot cover160, the refractive cover170, and the reflector180may be formed on the substrate112only by a dispensing or jetting process, instead of injection molding.

According to the disclosure, a display apparatus including a backlight unit having high productivity and low manufacturing cost may be provided. According to the disclosure, a display apparatus including a backlight unit capable of reducing production cost by reducing an amount of use of a quantum dot resin may be provided. According to the disclosure, a display apparatus including a light source having an optical profile of a great beam angle may be provided.

Although specific embodiments have been shown and described, the disclosure is not limited to the above-described embodiments, and various modifications can be made by those skilled in the art without departing from the gist of the technical idea of the disclosure defined by the claims below.