Backlight unit and display device provided therewith

Abstract

A backlight unit (200) for a display device, the backlight unit comprising: a substrate (210); a plurality of light-emitting devices (211) arranged on the substrate (210); a light source protection layer (215) disposed on the plurality of light-emitting devices (211), wherein an air gap is disposed between a top surface of the substrate (210) and a bottom surface of the light source protection layer (215) and between the light-emitting devices (211); a light conversion layer (216) disposed on the light source protection layer (215), the light conversion layer (216) comprising a plurality of light conversion patterns (216p) each disposed at positions corresponding to the plurality of light-emitting devices (211); and a phosphor film (217) arranged on the light conversion layer (216), wherein the light source protection layer (215) includes a first resin layer (215r1) covering the light-emitting devices (211) and a transparent film (215p) disposed on the first resin layer (215r1).

Description

BACKGROUND area

[0001] The embodiments of the present disclosure relate to a backlight unit and a display device provided therewith. Description of related technology

[0002] With the development of the information society, the demand for display devices for displaying images is increasing in various application fields. Recently, various display devices have been used for display devices, such as liquid crystal displays (LCDs), organic light-emitting displays (OLEDs), quantum dot light-emitting displays (QLEDs), and others.

[0003] A liquid crystal display device of various flat panel displays typically uses a light-emitting diode (LED), a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), and the like as a light source for a backlight unit. In recent years, light-emitting diodes, with excellent luminous efficiency and better color reproducibility, have been widely used as a light source for the backlight unit of a display device.

[0004] The backlight units can be classified into edge type, direct type, etc. according to the arrangement of the light sources and the transmission mode of the light. In the direct type of the backlight unit, the light source, such as an LED, may be arranged on the back of the display device.

[0005] US 2019 / 0137825 A1 describes a backlight unit comprising: a plurality of light-emitting diode packages on a top surface of a circuit board; an encapsulation layer located on the circuit board and covering the plurality of LED packages; and an integrated pattern film on the encapsulation layer, the integrated pattern film comprising: a base layer; a plurality of lens patterns on a top surface of the base layer and each corresponding to the plurality of LED packages; and void particles on a bottom surface of the base layer and in a region between the plurality of LED packages. In one example, a reflective pattern film is located under a diffusion plate.The reflective pattern sheet includes a base layer and a plurality of reflective patterns formed on a lower surface of the base layer and arranged to correspond to the plurality of LED packages, respectively.

[0006] JP 2002 231037 A describes an illumination device comprising a light-emitting surface and a plurality of near-point light sources, for example, LEDs, and is suitable for backlighting a liquid crystal display such as an LCD screen or a flat light-emitting device. For the illumination device, a plurality of cavities are formed on a light guide plate, and point light sources are housed in the respective cavities. A second layer is located at a distance of, for example, 0.1 mm from the light guide plate, and there is a gap between them.

[0007] WO 2012 / 091255 A1 describes a display device comprising a display panel and a backlight unit with a light source arranged on a rear side of the display panel to provide light. In one example, the backlight unit comprises a light guide layer and a light conversion layer bonded to a bottom side of an optical film. The light guide layer is provided as an air layer.

[0008] US 2018 / 0031759 A1 describes a light source module comprising a substrate, a plurality of light barriers on a surface of the substrate and spaced apart from each other, a plurality of light source packages on the surface of the substrate and positioned between the plurality of light barriers, and a total reflection induction layer on the plurality of light source packages. In one example, a light guide plate is arranged on the total reflection induction layer. In a comparative example, an optical module comprises a substrate, a light-emitting chip, and a lens portion surrounding the light-emitting chip. A gap is formed between the lens portion and the light guide plate. SHORT SUMMARY

[0009] It is an object of the present disclosure to provide a backlight unit that can reduce manufacturing costs and a display device provided therewith.

[0010] Furthermore, it is an object of the present disclosure to provide a backlight unit that can implement improved image quality and a display device provided therewith.

[0011] These objects are achieved by the subject matter of the independent claim. Further advantageous embodiments and refinements are described in the respective dependent claims.

[0012] Within the context of the present invention, a front side of a display device may be defined as a surface of the display device from which the display device emits light and / or displays an image. A front direction may be defined as a direction perpendicular to the front side. Similarly, a rear direction may be defined as the direction opposite to the front direction. A thickness of the display device and / or an element of the display device or the backlight unit for the display device may be defined with respect to the front direction. A width thereof may be defined according to a direction perpendicular to the front direction.When an element is described as being "behind" or "below" another element, the element is positioned along the rearward direction relative to the other element, whereas when an element is described as being "in front" or "above" another element, the element is positioned along the forward direction relative to the other element. Furthermore, a "top" or "front" of an element is a surface facing in the forward direction, whereas a "bottom" or "back" of an element is a surface facing in the rearward direction.

[0013] According to one aspect, a backlight unit for a display device comprises: a substrate, a plurality of light-emitting devices disposed on the substrate, a light source protection layer disposed on the plurality of light-emitting devices, wherein an air gap is disposed between a top surface of the substrate and a bottom surface of the light source protection layer and between the light-emitting devices; a light conversion layer disposed on the light source protection layer; and a phosphor film disposed on the light conversion layer.

[0014] A further air gap may be arranged between the light conversion layer and the light source protection layer.

[0015] The backlight unit may comprise at least one reflector disposed on the substrate. The air gap may be disposed between a top surface of the reflector and the bottom surface of the light source protection layer.

[0016] The at least one reflector may include a plurality of holes. At least one of the plurality of light-emitting devices may be arranged in a hole.

[0017] The light source protection layer may include a first resin layer covering the light-emitting devices. The light source protection layer may include a transparent film disposed on the first resin layer.

[0018] The first resin layer and the transparent film may be made of the same material and / or may have the same density.

[0019] The backlight unit may further comprise a bead layer disposed on the transparent film. The bead layer may include a first bead and a second bead with different refractive indices.

[0020] The first resin layer may be disposed in a hole of the reflector. A top surface of the first resin layer may be positioned higher than the top surface of the reflector.

[0021] The phosphor film may include a first region and a second region. A distance between the first region and one of the plurality of light-emitting devices may be greater than a distance between the second region and the one light-emitting device.

[0022] The air gap may be arranged on the top side of the reflector corresponding to the second region.

[0023] The light source protective layer may include a pattern having unevennesses on an upper surface of the light source protective layer corresponding to the first region.

[0024] The light source protective layer may include a pattern of unevenness on the underside of the light source protective layer corresponding to the first region.

[0025] The light source protection layer may include a second resin layer disposed on the upper side of the reflector corresponding to the first region.

[0026] The second resin layer may be in direct contact with the transparent element and the reflector so that no air gap is formed in the region where the second resin layer is arranged.

[0027] The second resin layer and the transparent film may be made of the same material and / or may have the same density.

[0028] The backlight unit may further comprise an optical layer disposed on the phosphor film.

[0029] The light conversion layer may include a plurality of light conversion patterns each arranged at positions corresponding to the plurality of light-emitting devices.

[0030] The light conversion pattern may be configured to adjust an emission direction of the light emitted from the light-emitting device.

[0031] The light conversion pattern may have a central portion having a thickness greater than the thickness of a peripheral portion thereof.

[0032] The light conversion pattern may be arranged in a region where an intensity of the light emitted by the light-emitting devices is strongest.

[0033] Furthermore, a display device according to one aspect of the present invention comprises a display panel; and a backlight unit as described above. The backlight unit may be arranged behind the display panel and may be configured to radiate light onto the display panel.

[0034] According to one aspect, there is provided a backlight unit comprising a light emitting section including a plurality of light-emitting devices arranged on a substrate, and a light source protection layer arranged on the plurality of light-emitting devices, wherein an air gap is arranged between a top surface of the substrate and a bottom surface of the light source protection layer, a light conversion layer having a plurality of light conversion patterns each arranged at positions corresponding to the plurality of light-emitting devices, and a phosphor film arranged on the light conversion layer.

[0035] The light source protection layer may include a first resin layer covering the light-emitting devices. The light source protection layer may include a transparent film disposed on the first resin layer and the substrate.

[0036] The backlight unit may further include at least one reflector having a plurality of holes in the substrate. The air gap may be arranged between a top surface of the reflector and the bottom surface of the light source protection layer.

[0037] The first resin layer may be disposed in the hole. A top surface of the first resin layer may be positioned higher than the top surface of the reflector.

[0038] The air gap may be arranged on the top side of the reflector corresponding to a second region of a first region and the second region of the phosphor film.

[0039] The light source protective layer may include a pattern of unevenness on an upper surface of the light source protective layer corresponding to a first region of the first region and a second region of the phosphor film.

[0040] The light source protective layer may include a pattern of unevenness on the underside of the light source protective layer corresponding to a first region of the first region and a second region of the phosphor film.

[0041] The reflector may include a second resin layer disposed on top of the reflector corresponding to a first region of the first region and a second region of the phosphor film.

[0042] The backlight unit may further comprise an optical layer disposed on the phosphor film.

[0043] The light conversion pattern may be configured to adjust an emission direction of the light emitted from the light-emitting device.

[0044] The light conversion pattern may have a central portion which is the thickest.

[0045] The light conversion pattern may be arranged in an area where the intensity of the light emitted by the light-emitting devices is strongest.

[0046] The first resin layer and the transparent film can have the same density.

[0047] The backlight unit may further comprise a bead layer disposed on the transparent film. The bead layer may include a first bead and a second bead having different refractive indices from each other.

[0048] According to another aspect, a display device includes a display panel and a backlight unit disposed below the display panel and irradiating light onto the display panel. The backlight unit may be a backlight unit as previously discussed. The backlight unit may include a light-emitting portion including a plurality of light-emitting devices disposed on a substrate, a light source protection layer disposed on the plurality of light-emitting devices, an air gap disposed between a top surface of the substrate and a bottom surface of the light source protection layer, a light conversion layer having a plurality of light conversion patterns each disposed at positions corresponding to the plurality of light-emitting devices, and a phosphor film disposed on the light conversion layer.

[0049] According to another aspect, a display device is provided that includes a display panel and a backlight unit. The backlight unit may be a backlight unit as previously disclosed. The backlight unit may include a light-emitting portion including a plurality of light-emitting devices arranged on a substrate, a light source protection layer arranged on the plurality of light-emitting devices, an air gap being arranged between a top surface of the substrate and a bottom surface of the light source protection layer, a light conversion layer having a plurality of light conversion patterns each arranged at positions corresponding to the plurality of light-emitting devices, and a phosphor film arranged on the light conversion layer.

[0050] The light source protection layer may include a first resin layer covering the light-emitting devices. The light source protection layer may include a transparent film disposed on the first resin layer and the substrate.

[0051] The backlight unit may further include at least one reflector having a plurality of holes in the substrate. The air gap may be arranged between a top surface of the reflector and the bottom surface of the light source protection layer.

[0052] The first resin layer may be disposed in the hole. A top surface of the first resin layer may be positioned higher than the top surface of the reflector.

[0053] The air gap may be arranged on the top side of the reflector corresponding to a second region of a first region and the second region of the phosphor film.

[0054] The light source protective layer may include a pattern of unevenness on an upper surface of the light source protective layer corresponding to a first region of the first region and a second region of the phosphor film.

[0055] The light source protective layer may include a pattern of asperities on the underside of the light source protective layer corresponding to a first region of the first region and a second region of the phosphor film.

[0056] The reflector may include a second resin layer disposed on top of the reflector corresponding to a first region of the first region and a second region of the phosphor film.

[0057] The backlight unit may further comprise an optical layer disposed on the phosphor film.

[0058] The light conversion pattern may be configured to adjust an emission direction of the light emitted from the light-emitting device.

[0059] The light conversion pattern may have a central portion which is the thickest.

[0060] The light conversion pattern may be arranged in an area where the intensity of the light emitted by the light-emitting devices is strongest.

[0061] The first resin layer and the transparent film can have the same density.

[0062] The backlight unit may further comprise a bead layer disposed on the transparent film. The bead layer may include a first bead and a second bead having different refractive indices from each other.

[0063] According to the embodiments of the present disclosure, it is possible to provide a backlight unit that can reduce manufacturing costs and a display device provided therewith.

[0064] Furthermore, according to the embodiments of the present disclosure, it is possible to provide a backlight unit that can implement improved image quality and a display device including the same. DESCRIPTION OF THE DRAWINGS

[0065] The above and other objects, features and advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a structural diagram illustrating a display device according to embodiments of the present disclosure; Fig. 2 is a cross-sectional view illustrating a display device according to embodiments of the present disclosure; Fig. 3 is a view showing a path of light traveling in a backlight unit according to embodiments of the present disclosure; Fig. 4 is a view showing a path of light traveling in the backlight unit according to embodiments of the present disclosure; Fig. 5A, Fig. 5B and Fig. 5C are schematic views illustrating a method of forming an air gap in a backlight unit according to embodiments of the present disclosure; Fig. 6A is a cross-sectional view schematically showing a backlight unit according to embodiments of the present disclosure; Fig. 6B is an enlarged view of a portion of the backlight unit as shown in Fig. 6A is shown; Fig. 7 and Fig. 8 are cross-sectional views showing a backlight unit according to the embodiment of the present disclosure; Fig. 9 is a set of cross-sectional views schematically illustrating various shapes of the patterns arranged on a transparent film included in the backlight unit; Fig. 10 is a plan view showing a portion of a light source protective layer on which a predetermined pattern is formed; Fig. 11 is a cross-sectional view illustrating a backlight unit according to embodiments of the present disclosure; Fig. 12 is a perspective view illustrating a reflector applied in a backlight unit according to embodiments of the present disclosure; Fig. 13 is a view schematically showing a first embodiment of the structure of a backlight unit according to the embodiments of the present disclosure; and Fig. 14A and Fig. 14B are views illustrating an example of the structure according to the position of the light conversion patterns included in the backlight unit shown in Fig. 13 is shown. DETAILED DESCRIPTION

[0066] In the following description of examples or embodiments of the present disclosure, reference is made to the accompanying drawings, in which, for illustrative purposes, specific examples or embodiments that may be implemented are shown, and in which the same reference numbers and characters may be used to designate the same or similar components even though they are shown in different accompanying drawings. Furthermore, in the following description of examples or embodiments of the present disclosure, detailed descriptions of well-known functions and components included herein are omitted when it is determined that the description may make the subject matter in some embodiments of the present disclosure rather unclear. The terms used herein, such as"Including," "having," "containing," "constituting," and "comprising" are generally intended to allow for the addition of other components unless the terms are used with the term "only." As used herein, the singular forms are intended to include the plural forms unless the context clearly indicates otherwise.

[0067] Terms such as "first," "second," "A," "B," "(a)," or "(b)" may be used herein to describe the elements of the present disclosure. Each of these terms is not used to define the nature, order, sequence, or number of the elements, etc., but is used merely to distinguish the corresponding element from other elements.

[0068] When it is mentioned that a first element is “connected or coupled” to a second element, a second element “overlaps,” etc., it should be interpreted that not only can the first element be “directly connected or coupled” to the second element or the second element “directly overlap,” but also a third element can be “interposed” between the first and second elements, or the first and second elements can be “connected or coupled” to each other via a fourth element, “overlap,” etc. Here, the second element can be included in at least one of two or more elements that are “connected or coupled,” “overlap,” etc., to each other.

[0069] When time-relative terms such as "after," "subsequent," "next," "before," and the like are used to describe processes or operations of elements or configurations or sequences or steps in methods of operation, processing, or manufacturing, these expressions may be used to describe non-consecutive or non-sequential processes or operations unless the term "direct" or "immediate" is also used.

[0070] When mentioning any dimensions, relative sizes, etc., it should also be considered that numerical values for elements or characteristics, or corresponding information (e.g., level, range, etc.), include a tolerance or error range that may be caused by various factors (e.g., process factors, internal or external influences, noise, etc.), even if no relevant description is specified. Furthermore, the term "may" fully encompasses all meanings of the term "can."

[0071] Fig. 1 is a structural diagram illustrating a display device according to embodiments of the present disclosure.

[0072] In Fig. 1, the display device 10 according to embodiments of the present disclosure may include a display panel 100 having an active area (A / A) and a non-active area (N / A), and a gate driver 120, a data driver 130, and a controller 140 for driving the display panel 100.

[0073] A plurality of gate lines GL and a plurality of data lines DL may be arranged on the display panel 100, and at least one sub-pixel SP may be arranged in a region where the gate line GL and the data line DL intersect. Furthermore, the display panel 100 may be composed of a liquid crystal panel, which may include at least one pixel electrode, at least one common electrode, and at least one liquid crystal layer disposed between the at least one pixel electrode and the at least one common electrode. The liquid crystal layer may be configured to cause its molecular arrangement to change in response to the voltages applied to the pixel electrode and the common electrode, so as to block or transmit light through the liquid crystal layer to display an image.

[0074] Gate driver 120 may be configured to be controlled by controller 140 and to perform drive timing control of a plurality of sub-pixels SP by sequentially outputting scan signals to the plurality of gate lines GL arranged on display panel 100. Gate driver 120 may include at least one gate driver integrated circuit (GDIC) and may be arranged on either one side or both sides of display panel 100 according to a driving scheme used.

[0075] Each gate driver integrated circuit can be connected to a bonding pad of the display panel 100 using the automatic film bonding (TAB) or chip-on-glass (COG) process, or can be implemented in a gate-in-panel (GIP) type to be disposed directly on the display panel 100, or it can be integrated into the display panel 100, as required by the circumstances. Furthermore, the gate driver integrated circuit can be implemented using a chip-on-film (COF) process, in which the circuit is adapted to be mounted on a film bonded to the display panel 100.

[0076] Data driver 130 may be configured to receive the image data from controller 140 and convert the received image data into a sequence of analog data voltages. Data driver 130 may be configured to output a data voltage to each data line DL in accordance with the timing at which the scanning signals are applied through gate line GL, so that each subpixel SP can display the brightness according to the image data.

[0077] The data driver 130 may include at least one source driver integrated circuit (SDIC), which may include, but is not limited to, a shift register, a latch, a digital-to-analog converter, and an output buffer.

[0078] Each source driver integrated circuit may be configured to be connected to a bonding pad of the display panel 100 using the automatic film bonding (TAB) or the chip-on-glass (COG) process, or may be disposed directly on the display panel 100. Furthermore, each source driver integrated circuit may be implemented using the chip-on-film (COF) process, in which each source driver integrated circuit may be mounted on a film bonded to the display panel 100 and electrically connected to the display panel 100 through the wiring in the film.

[0079] The controller 140 may be configured to supply various control signals to the gate driver 120 and the data driver 130 to control the operation of the gate driver 120 and the data driver 130. The controller 140 may be mounted on a circuit board or, preferably, a flexible circuit board, and may be electrically connected to the gate driver 120 and the data driver 130 through this circuit board. The controller 140 may be configured to control the gate driver 120 to adaptively output the scanning signals according to the operation timing to be implemented in each frame. Furthermore, the controller 140 may be configured to convert externally received image data in accordance with a data signal format usable in the data driver 130 and then output the converted image data DATA to the data driver 130. The controller 140 may further be configured to receive data from any external source (e.g.,a host system) to receive various timing signals, such as a vertical synchronization signal VSYNC, a horizontal synchronization signal HSYNC, an input data enable signal DE, and a clock signal CLK, along with the image data.

[0080] Then, the controller 140 may be configured to generate various control signals using the various timing signals received from the external source to supply them to the gate driver 120 and the data driver 130. To control the gate driver 120, the controller 140 may typically be configured, for example, to provide various gate control signals GCS, including, for example, a gate start pulse GSP, a gate shift clock GSC, a gate output enable signal GOE, etc. Here, the gate start pulse GSP may be configured to control the operation start timing of at least one gate driver integrated circuit constituting the gate driver 121.

[0081] The gate shift clock GSC may be a clock signal typically input to at least one gate driver integrated circuit for controlling the shift timing of the scanning signals. The gate output enable signal GOE may be configured to specify the timing information of the at least one gate driver integrated circuit.

[0082] To control the data driver 130, the controller 140 may be further configured to output various data control signals DCS, including, for example, a source start pulse SSP, a source sampling clock SSC, a source output enable signal SOE, etc. Here, the source start pulse SSP may be configured to control the data sampling start timing of at least one source driver integrated circuit constituting the data driver 130. The source sampling clock SSC may be a clock signal for controlling the data sampling timing in each source driver integrated circuit. Furthermore, the source output enable signal SOE may be configured to control the output timing of the data driver 130.

[0083] Then, the display device 10 may be further configured to include an integrated power management circuit to supply different voltages and / or currents to the display panel 100, the gate driver 120, the data driver 130, etc., or to control these different voltages and / or currents to be supplied to them.

[0084] Fig. 2 is a cross-sectional view illustrating a display device according to embodiments of the present disclosure.

[0085] In Fig. 2, the display device 10 according to embodiments of the present disclosure may include a display panel 100 and a backlight unit 200 disposed below the display panel 100 and supplying light to the display panel 100.

[0086] Some structural elements may be arranged between the backlight unit 200 and the display panel 100, and the display panel 100 may be arranged on the backlight unit 200 by means of, for example, a guide plate 400, a foam pad 500, and others, but the arrangement is not limited thereto.

[0087] The backlight unit 200 may include a cover base 300 to accommodate optical elements and the like that form the backlight unit 200.

[0088] The substrate 210 may be arranged on the cover base 300, and a plurality of light-emitting devices 211 may be arranged on the substrate 210. The light-emitting device 211 may be, for example, a light-emitting diode (LED), or may be a small mini-LED or a micro-LED, and this light-emitting device 211 may have a flip-chip structure. The flip-chip structure of the light-emitting device 211 may be arranged in such a way that the chip-type light-emitting device 211 is mounted on the substrate 210, thereby making it possible to reduce the thickness of the backlight unit 200 and thus provide a light source with a wider range of light emission angles and better luminous efficiency.

[0089] The light-emitting device 211 can emit light in a white wavelength band or emit light in a specific wavelength band (e.g., a blue wavelength band), as required by the circumstances. The substrate 210 can be a printed circuit board.

[0090] Furthermore, a light source protection layer 215 may be disposed on the substrate 210 on which the plurality of light-emitting devices 211 are disposed. The light source protection layer 215 may include a transparent member. The light source protection layer 215 may further include PET (polyethylene terephthalate). The light source protection layer 215 may be configured to protect the plurality of light-emitting devices 211 and provide a function for diffusing the light emitted by the light-emitting devices 211.

[0091] A light conversion layer 216 may be disposed on the light source protection layer 215. The light conversion layer 216 may be configured to cause scattering, reflection, or diffraction of the light emitted by the light-emitting device 211. Furthermore, the light conversion layer 216 may be configured to transmit some of the light emitted by the light-emitting devices 211. The light conversion layer 216 may be composed of a light control sheet that can transmit a portion of the light. The light conversion layer 216 may be configured to prevent hot spots from being generated in the backlight unit 200. The light conversion layer 216 may include a plurality of light conversion patterns 216p, wherein the light conversion patterns 216p may be arranged to overlap each of the plurality of light-emitting devices 211.

[0092] The light conversion pattern 216p can adjust an emission direction of the light emitted by the light-emitting device 211, e.g., cause some of the light emitted by the light-emitting device 211 to undergo scattering, reflection, or diffraction. Furthermore, the light conversion pattern 216p can cause some of the light emitted by the light-emitting device 211 to transmit. The light conversion pattern 216p can be a light control pattern that can transmit a portion of the light. The light conversion pattern 216p causes the light emitted by the light-emitting devices 211 to undergo scattering, reflection, diffraction, and / or transmission, so that the light conversion layer 216 can make the luminance of the backlight unit 200 uniform.

[0093] The light conversion pattern 216p may be arranged to overlap the light-emitting device 211, and thus the light conversion pattern 216p may be arranged in a region where the intensity of the light emitted by the light-emitting device 211 is the strongest. Therefore, it makes it possible to reduce the luminance deviation between the region where the light-emitting device 211 is arranged (i.e., a region with a larger amount of light) and the region between the light-emitting devices 211 (i.e., a region with a smaller amount of light). Additionally, an air gap may be formed between the light conversion patterns 216p.

[0094] The light conversion layer 216 may contain a light conversion material, and the light conversion patterns 216p of the light conversion layer 216 may further contain a light conversion material. The light conversion material may contain titanium dioxide (TiO2). Furthermore, the light conversion material may be white, although not limited thereto.

[0095] As a result, the light conversion layer 216 can reduce luminance variation, making it possible to suppress the occurrence of so-called "mura" in any edge region of the light-emitting devices 211 in the backlight unit 200, which causes the displayed screen characteristics to become non-uniform, such as a spotty state. Consequently, the luminance of the light emitted by the backlight unit 200 can be more uniform.

[0096] A phosphor film 217 may be disposed on the light conversion layer 216. The phosphor film 217 may contain a phosphor and generate light emission by the light irradiated onto the phosphor film 217. If the light incident on the phosphor film 217 is blue light, the light passing through the phosphor film 217 may be converted into white light by the light emitted by the phosphor.

[0097] The light conversion pattern 216p is illustrated as being arranged adjacent to the light source protection layer 215, but the arrangement is not limited thereto, and the light conversion pattern 216p may be arranged adjacent to the phosphor film 217.

[0098] Additionally, a reflective film may be applied to the substrate 210. The reflective film may contain a white pigment, although not limited thereto. The reflective film may cause the substrate 210 to experience light reflection to further increase the light output of the backlight unit 200. Furthermore, at least one reflector 212 may be disposed on the substrate 210.

[0099] The reflector 212 may be configured to cause reflection of the light scattered by the light source protection layer 215 so that it is emitted toward the phosphor film 217, thereby making the luminance of the backlight unit 200 more uniform.

[0100] Furthermore, an adhesive film 219 may be disposed between the light source protection layer 215 and the light conversion layer 216. The adhesive film 219 may be made of an optically transparent adhesive film (OCA film). The adhesive film 219 serves to enable the light conversion layer 216 to be attached to the light source protection layer 215.

[0101] Fig. 3 is a view showing the path of light traveling in a backlight unit according to embodiments of the present disclosure.

[0102] In Fig. 3, some of the light emitted by the light-emitting device 211 is allowed to pass through the light conversion pattern 216p of the light conversion layer 216 and then through the phosphor film 217 disposed on the light conversion layer 216. Then, the light passing through the phosphor film 217 can be evenly irradiated onto the display panel 100 through an optical layer 218.

[0103] Some of the light emitted from the light-emitting device 211 is caused to be reflected or scattered by the light conversion layer 216p to travel to the reflector 212, and then reflected again by the reflector 212 to pass through the phosphor film 217. The intensity of the light emitted perpendicular to the phosphor film 217 from the light-emitting device 211 becomes relatively weak, while the intensity of the light emitted toward the area between the light-emitting devices 211 becomes relatively stronger, so that the luminance of the light from the backlight unit 200 can be made more uniform.

[0104] However, when the number of light-emitting devices 211 included in the backlight unit 200 is reduced or the area of a screen portion displaying an image in the display panel 100 increases, the distance between the light-emitting devices 211 widens. Consequently, when the distance between the light-emitting devices 211 becomes further apart, the length of the reflector 212 can be increased.

[0105] A light-emitting surface of the phosphor film 217 may be divided into two sections, ie, a first region A1 and a second region A2. The first region A1 is defined to be located at a position farther from the light-emitting device 211 than the second region A2. In other words, the second region A2 is located closer to the light-emitting device 211 than the first region A1. Furthermore, the first region A1 may correspond to the central portion of the reflector 212 located between the light-emitting devices 211.

[0106] Then, as the distance between the light-emitting devices 211 becomes longer, a problem often arises that the intensity of the emitted light in the first region A1 of the phosphor film 217 becomes weak, so that the luminance of the backlight unit 200 becomes uneven even if the light is caused to undergo reflection from the reflector 212. Consequently, it often leads to a problem that it is difficult for a designer of the backlight unit to reduce the number of light-emitting devices 211 arranged on the substrate 210.

[0107] In other words, because most of the light incident on the reflector 212 is reflected toward the phosphor film 217 in the second area A2, the light incident on the phosphor film 217 corresponding to the first area A1 may be very weak or absent. Therefore, a problem that the luminance becomes uneven may remain unsolved.

[0108] Fig. 4 is a view showing a path traveled by light in the backlight unit according to embodiments of the present disclosure.

[0109] In Fig. 4, some of the light emitted by the light-emitting device 211 may now pass through the light conversion pattern 216p of the light conversion layer 216 and then pass through the phosphor film 217 disposed on the light conversion layer 216. Then, some of the light emitted by the light-emitting device 211 may be reflected or scattered in the light conversion pattern 216p, and may continue to pass through the phosphor film 217 after being reflected again by the reflector 212.

[0110] Consequently, the intensity of the light emitted perpendicular to the phosphor film 217 into the light-emitting device 211 becomes relatively weak, while the intensity of the light emitted to the area between the light-emitting devices 211 becomes relatively strong compared to the light emitted perpendicular to the phosphor film 217, so that the luminance of the backlight unit 200 can become more uniform.

[0111] According to embodiments of the present disclosure, an air gap may be provided between a top surface of the reflector 212 and the light source protection layer 215. The light radiated onto the reflector 212 may be reflected by the air gap to travel toward the phosphor film 217 again. At the boundary between the light source protection layer 215 and the light conversion layer 216, the light is caused to undergo total internal reflection. Furthermore, the light conversion layer 216 may be disposed such that a portion where no light conversion pattern 216p is disposed is spaced from the light source protection layer 215 due to the presence of the light conversion pattern 216p, and an air gap is formed in the spaced portion.Accordingly, the boundary between the light source protection layer 215 and the light conversion layer 216 can be a boundary between the light source protection layer 215 and the air gap. Furthermore, due to such total internal reflection, the distance the light travels in a first direction F1 can be further increased.

[0112] As the distance the light emitted from the light-emitting device 211 travels in the first direction F1 increases, the light can be irradiated onto the first region A1 of the phosphor film 217, so that the above-mentioned problem of uneven luminance in the backlight unit 200 can be effectively solved. Therefore, even if the distance between the light-emitting devices 211 increases, it becomes possible to prevent uneven luminance from being generated in the backlight unit 200, so that the number of light-emitting devices 211 arranged on the substrate 210 can be reduced, and thus the manufacturing cost of the display device 10 can be greatly reduced.

[0113] The Fig. 5A, Fig. 5B and Fig. 5C are schematic views illustrating a method of forming the air gap in the backlight unit according to embodiments of the present disclosure.

[0114] As in Fig. 5A, at least one light-emitting device 211 and at least one reflector 212 may be arranged on the substrate 210. The reflector 212 may include a plurality of holes, as shown in Fig. 12, wherein the reflector 212 may be arranged on the substrate 210 in such a manner that the light-emitting device 211 may be arranged in each hole.

[0115] Then, as in Fig. 5B, a first resin layer 215r1 may be disposed in the hole. The top surface of the first resin layer 215r1 may be located at a higher position than the top surface of the reflector 212. Therefore, the first resin layer 215r1 may be formed to protrude from the reflector 212. Additionally, the first resin layer 215r1 may contain a transparent resin.

[0116] Further, a transparent element (or a transparent film) 215p may be arranged as shown in Fig. 5C. The transparent member 215p may be made of a plastic film. The first resin layer 215r1 and the transparent member 215p may form the light source protection layer 215. The transparent member 215p may be made of, but is not limited to, PET (polyethylene terephthalate). Although it is illustrated here that there is a boundary between the first resin layer 215r1 and the transparent member 215p, the present disclosure is not limited thereto, and the first resin layer 215r1 and the transparent member 215p may be formed of a transparent material and / or the same material so that their boundary does not appear visible. In addition, the first resin layer 215r1 and the transparent member 215p may have the same density.

[0117] Because the first resin layer 215r1 is formed to protrude from the top surface of the reflector 212, the top surface of the first resin layer 215r1 is higher than the top surface of the reflector 212, so that the first resin layer 215r1 can be configured to support the transparent member 215p.

[0118] Accordingly, the first resin layer 215r1 may be in close contact with the transparent member 215p at a position overlapping the light-emitting device 211.

[0119] The first resin layer 215r1 and the transparent member 215p may be included in the light source protection layer 215.

[0120] On the other hand, a predetermined gap may be formed between the top surface of the reflector 212 and the bottom surface of the transparent member 215p, and the predetermined gap may be an air gap. Thus, the air gap may be located between the top surface of the reflector 212 and the bottom surface of the transparent member 215p. Because the light source protection layer 215 includes the first resin layer 215r1 and the transparent member 215p, the air gap may be located between the top surface of the reflector 212 and the bottom surface of the light source protection layer 215. Furthermore, the light source protection layer 215 may be attached to the light-emitting device 211 via the first resin layer 215r1.

[0121] Fig. 6A is a cross-sectional view schematically showing the backlight unit according to the embodiments of the present disclosure, while Fig. 6B is an enlarged view of a portion of the backlight unit as shown in Fig. 6A is shown.

[0122] In the Fig. 6A and Fig. 6B, the arrangement can now be manufactured such that no air gap is arranged on the reflector 212 at a position corresponding to the first area A1 of the phosphor film 217. Consequently, total internal reflection is not generated in the central portion of the reflector 212, which is arranged between the light-emitting devices 211, so that the reflector 212 can cause reflection of the light toward the display panel 100 (or toward the phosphor film 217).

[0123] The occurrence of such total internal reflection may cause a problem that the light irradiation onto the phosphor film 217 is not effective. However, if total internal reflection is not generated in the central portion of the reflector 212, the light can be irradiated onto the first region A1 of the phosphor film 217, thereby effectively preventing luminance unevenness. A second resin layer 215r2 may be formed on the central portion X of the reflector 212, and a transparent member 215p may be disposed on the second resin layer 215r2. The second resin layer 215r2 may be in contact with the transparent member 215p to support the transparent member 215p.Therefore, in the region where the second resin layer 215r2 is disposed on the reflector 212, the second resin layer 215r2 and the transparent member 215p are in contact with each other, so that no air gap is formed in a region where the second resin layer 215r2 is disposed on the reflector 212.

[0124] Although it is illustrated that a boundary exists between the second resin layer 215r2 and the transparent element 215p, the arrangement is not limited thereto. The second resin layer 215r2 and the transparent element 215p may contain a transparent material and / or may contain the same material so that such a boundary between the second resin layer 215r2 and the transparent element 215p is not visible. Additionally, the second resin layer 215r2 and the transparent element 215p may have the same density.

[0125] The Fig. 7 and Fig. 8 are cross-sectional views showing a backlight unit according to the embodiment of the present disclosure, and Fig. 9 is a set of cross-sectional views schematically illustrating various shapes of patterns arranged on a transparent film included in the backlight unit.

[0126] As in Fig. As shown in Figure 7, by forming a pattern containing unevenness on the upper side of the transparent member 215p, the arrangement can be manufactured such that no total reflection occurs at a position corresponding to the first region A1 of the phosphor film 217. In other words, total reflection in the first region A1 is prevented by the patterns. As shown in Fig. Further, as shown in Figure 8, such a pattern including unevenness may be formed on the underside of the light source protection layer to prevent total reflection from occurring at a position corresponding to the first region A1 of the phosphor film 217. Total reflection can be prevented by the pattern by scattering the light passing through the transparent member 215p.

[0127] As shown in the exemplary patterns (a) to (d) according to Fig. As illustrated in Figure 9, the patterns arranged on the top or bottom of the transparent element 215p may be formed in an intaglio or embossed form on the transparent element 215p, wherein the cross-sectional shape of the patterns may advantageously be semicircular or triangular, although the shape of the patterns is not limited thereto. Furthermore, a pearl layer 215f may be printed on the transparent element 215p, as shown in (e) of Fig. 9, the bead layer 215f may include a plurality of beads. The beads included in the bead layer 215f may include at least one selected from the group consisting of polymethyl methacrylate (PMMA), polybutyl methacrylate (PBMA), polystyrene, and silicon. The plurality of beads may include a first bead and a second bead having different refractive indices from each other. The refractive index of the first bead and the second bead may be between 1.45 and 1.55. Furthermore, the average diameter of the beads may range from 1 to 15 µm. The shape of the beads may be circular or oval, but the size and shape of the beads 215f are not limited thereto.

[0128] The beads may be arranged on the transparent element 215p, and an adhesive material, such as a resin, may be arranged beneath the beads so that the beads can be secured to the transparent element 215p. Consequently, these beads may serve to scatter the light passing through the transparent element 215p, which is arranged beneath the beads, to prevent total internal reflection from being generated at the transparent element 215p.

[0129] Furthermore, titanium dioxide (TiO2) can be printed in a circular or oval shape or other shape on the transparent element 215p. Therefore, titanium dioxide (TiO2) can prevent total internal reflection from being generated at the transparent element 215p.

[0130] Fig. 10 is a plan view showing a portion of a light source protective layer on which a specific pattern is formed.

[0131] In Fig. 10, the light source protection layer 215 may be transparent so that the light-emitting devices 211a to 211d arranged below the light source protection layer 215 can be seen from the outside. These four light-emitting devices 211a to 211d may be arranged at a certain distance from the bottom of the light source protection layer 215.

[0132] The above pattern may include a first pattern 215p1 and a second pattern 215p2, wherein the first pattern 215p1 may be arranged between a first light-emitting device 211a and a second light-emitting device 211b, and between a third light-emitting device 211c and a fourth light-emitting device 211d, between the first light-emitting device 211a and the third light-emitting device 211c, and between the second light-emitting device 211b and the fourth light-emitting device 211d. Furthermore, the first pattern 215p1 may be arranged between the first light-emitting device 211a and the fourth light-emitting device 211d. Furthermore, the second pattern 215p2 may be arranged within a virtual rectangle whose vertices correspond to the respective positions of the four light-emitting devices 211a to 211d.The first pattern 215p1 and the second pattern 215p2 may have differences in the height and area of the bumps. In other words, the height and area of the bumps of the first pattern 215p1 may be smaller than the height and area of the bumps of the second pattern 215p2, although the shape of the bumps is not limited thereto. Furthermore, the second pattern 215p2 may have a larger number of patterns per unit area in the central portion (a portion far from the light-emitting device), while having a smaller number of patterns per unit area as it progresses toward the outer portion (a portion closer to the light-emitting device).

[0133] Although the first pattern 215p1 and the second pattern 215p2 are both formed on the light source protection layer 215 here, the arrangement as disclosed is not limited thereto, and either the first pattern 215p1 or the second pattern 215p2 may be formed on the light source protection layer 215.

[0134] Fig. 11 is a cross-sectional view illustrating the backlight unit according to embodiments of the present disclosure.

[0135] In Fig. 11, the light-emitting devices 211 may be arranged on the substrate 210. Furthermore, an air gap may be arranged between the light-emitting devices 211 on the substrate 210. That is, the reflector 212 is not arranged on the substrate 210, and consequently, the thickness of the light source protection layer 215 may be thicker than the thickness of the light source protection layer 215, as shown in FIGS. Fig. 4, Fig. 6A, Fig. 7 and Fig. 8 is shown.

[0136] In the backlight unit 200, the air gap disposed on the substrate can cause total internal reflection at the air gap and at the boundary between the light source protection layer 215 and the light conversion layer 216. Furthermore, if the thickness of the light source protection layer 215 is relatively thick, the light can be more widely scattered within the light source protection layer 215.

[0137] The formation of such an air gap on the substrate 210 can form a first resin layer covering the light-emitting device 211 arranged on the substrate 210, wherein a transparent element can be arranged on the first resin layer. The transparent element can be in close contact with the resin layer in the upper portion of the first resin layer, but the portion where no resin layer is formed can be a certain distance from the substrate 210, since the first resin layer is formed to support the transparent element. Consequently, an air gap can be formed between the bottom surface of the transparent element and the top surface of the substrate 210. The transparent element and the first resin layer can be included in the light source protection layer 215. The Fig. 9 may advantageously be formed on the transparent element and / or a second resin layer may be arranged between the light-emitting devices 211, as shown in Fig. 6B. Then, the second resin layer can be brought into contact with the transparent member so that no air gap is formed between the second resin layer and the light-emitting devices 211. The first resin layer, the second resin layer, and the transparent member can have the same density, although they are not limited thereto. The embodiment according to Fig. 11 may be combined with other embodiments as disclosed herein.

[0138] Fig. 12 is a perspective view illustrating the reflector applied in the backlight unit according to embodiments of the present disclosure.

[0139] In Fig. 12, the reflector 212 may be arranged correspondingly to the substrate 210. The reflector 212 may include a plurality of holes. The light-emitting device 211 may be arranged in the center of the hole. Although the shape of the hole is shown as circular, it is not limited to this.

[0140] Fig. 13 schematically shows a first embodiment of the structure of the backlight unit according to the embodiments of the present disclosure. The embodiment according to Fig. 13 may be combined with other embodiments as disclosed herein.

[0141] In Fig. 13, the substrate 210 may be arranged on a cover base 300, wherein the substrate 210 may be attached to the cover base 300 by means of an adhesive tape 210a arranged between the cover base 300 and the substrate 210.

[0142] A plurality of light-emitting devices 211 may be arranged on the substrate 210, wherein at least one reflector 212 may be arranged in at least a portion of a region other than the region in which the light-emitting devices 211 are arranged.

[0143] Here, the light-emitting device 211 may be, for example, a light-emitting diode (LED), which may further include a light-emitting element 211a having an n-type semiconductor layer, an activation layer, and a p-type semiconductor layer, and an electrode 211b. A light source protection layer 215 may be disposed on the plurality of light-emitting devices 211 and the reflectors 212. A light conversion layer 216 having a light conversion pattern 216p thereon may be disposed at a position corresponding to the light-emitting device 211 on the light source protection layer 215. Further, a phosphor film 217, an optical layer 218, and others may be disposed on the light conversion layer 216.

[0144] The light conversion pattern 216p arranged on the underside of the light conversion layer 216 can be implemented by enabling a specific material with specific light conversion properties to be printed onto the light conversion layer 216, preferably, for example, by printing a specific pattern of a TiO2-containing ink onto the light conversion layer 216. Furthermore, the light conversion pattern 216p arranged on the underside of the light conversion layer 216 can be formed either from a single layer or in a multi-layer structure. That is, the light conversion pattern 216p arranged on the underside of the light conversion layer 216 can be formed from at least three layers, as shown in Fig. 13. This light conversion pattern 216p can be implemented by printing the light conversion material three times on the light conversion layer 216, gradually narrowing the area of the printed light conversion material. Furthermore, the light conversion pattern 216p can be formed on the light-emitting device 211 by inverting the light conversion layer 216 on which the light conversion pattern 216p is disposed, and then disposing the light conversion layer 216 on the light source protection layer 215.

[0145] Therefore, the area of the light conversion pattern 216p may be gradually narrowed downward from the bottom of the light conversion layer 216, and the thickness in the central portion of the light conversion pattern 216p may be larger than the thickness in its edge portion, peripheral portion, or outer portion.

[0146] In other words, since the intensity of the light output in the vertical direction from the light-emitting device 211 is the largest, the central portion of the light conversion pattern 216p can be made thicker, although it is not limited thereto.

[0147] As described above, the arrangement of the light conversion pattern 216p on the light-emitting device 211 allows at least part of the light output from the light-emitting device 211 to be blocked in the vertical direction to prevent a hot spot from occurring in an area where the light-emitting device 211 is arranged. The light conversion layer 216, on which the light conversion pattern 216p is arranged, may be attached to the light source protection layer 215 by an adhesive film 219. At this point, the adhesive film 219 may be arranged on at least some of an area, excluding the area where the light conversion pattern 216p is arranged, on the underside of the light conversion layer 216.

[0148] Therefore, the adhesive film 219 may not be disposed in the area where the light conversion pattern 216p is disposed, and an air gap may be provided between the light conversion pattern 216p and the light source protection layer 215. Further, a side portion of the light conversion pattern 216p and the adhesive film 219 may be spaced apart from each other. Since the air gap is provided between the light conversion pattern 216p and the light source protection layer 215, the light output in the lateral direction of the light conversion pattern 216p may be caused to be reflected by the air gap. That is, the light output in the lateral direction of the light conversion pattern 216p may be emitted through the air layer with a low refractive index at a large refractive angle or reflected by the air layer.Furthermore, the light reflected from the air layer is reflected again by the reflector 212 and then output, thereby increasing the luminous efficiency while assisting the light conversion function of the light conversion pattern 216p.

[0149] As described above, it is possible to increase the luminous efficiency of the backlight unit while preventing the occurrence of hot spots by the structure in which the light conversion elements 211p and the air gaps are arranged at the positions corresponding to the light-emitting devices 211. Furthermore, the light conversion patterns 216p arranged below the light conversion layer 216 may be arranged in a different structure according to their arranged positions.

[0150] The Fig. 14A and Fig. 14B illustrate examples of the light-emitting structures according to the positions of the light conversion patterns included in the backlight unit as shown in Fig. 13 is shown.

[0151] First, Fig. 14A, which illustrates examples of the luminance appearing by the backlight unit 200 according to the structure of the light conversion patterns 216p, the example <ex1>represents the luminance measured when the light conversion patterns 216p are arranged in a certain regular pattern of the structure, whereas the example <ex2>represents the luminance measured when the light conversion patterns 216p are arranged in a different pattern of the structure according to the positions at which the light conversion patterns 216p are arranged.

[0152] As in the example <ex1>after Fig. 14A, the luminance in the outer region of the backlight unit 200 may appear lower than that of its central region when the light conversion pattern 216pa arranged in the outer region of the backlight unit 200 and the light conversion pattern 216pd arranged in its central region are substantially similar to each other in their structures.

[0153] In other words, because the outer region of the backlight unit 200 has a relatively small number of light-emitting devices 211 that supply light to the corresponding outer region, the outer region of the backlight unit 200 may have a lower quality of luminance compared to the central region of the backlight unit 200 if the light conversion patterns 216p having the same level of light conversion characteristics are arranged thereon.

[0154] Therefore, it is possible to prevent deterioration of the luminance in the outer region of the backlight unit 200 by arranging the light conversion pattern 216pa in the outer region of the backlight unit 200 in a different structure than the light conversion pattern 216pa in its central region, as in the example <ex2>after Fig. 14A, thus making the overall luminance on the display device more uniform.

[0155] As an example, the light conversion patterns 216p may be arranged such that the thickness T1 of the light conversion pattern 216pa arranged in the outer region of the backlight unit 200 is smaller than the thickness T2 of the light conversion pattern 216pd arranged in its central region.

[0156] Alternatively or additionally, the light conversion pattern 216p may be arranged such that the area W1 of the thickest portion in the light conversion pattern 216pb located adjacent to the outer region of the backlight unit 200 is smaller than the area W2 of the thickest portion in the light conversion pattern 216pa located in the central region. In other words, the light conversion patterns 216p may be arranged such that the portion with higher blocking properties has a smaller area in the light conversion patterns 216pa and 216pb located in the outer region of the backlight unit 200 or in a region adjacent to the outer region.

[0157] Furthermore, the light conversion patterns 216p may be arranged so that the thickness of the light conversion pattern 216p gradually decreases, or the area of the thickest portion in the light conversion pattern 216p gradually decreases as it moves from the central region to the outer region of the backlight unit 200. As is apparent from the foregoing, the portion with higher blocking properties in the light conversion patterns 216pa and 216pb arranged in the outer region of the backlight unit 200 or in a region adjacent to the outer region may be arranged to have a smaller area.

[0158] In addition, in some cases, the light conversion patterns 216p may be arranged in such a different pattern that the distance between the light-emitting devices 211 or the number of the light-emitting devices 211 in the central region and the outer region of the backlight unit 200 may be different from each other.

[0159] In Fig. 14B shows another example of the structure in which the light conversion patterns 216p are arranged on a bottom surface of the light conversion layer 216.

[0160] Here, the pitch between the light-emitting devices 211 arranged in the outer region of the backlight unit 200 may be narrower than the pitch between the light-emitting devices 211 arranged in the central region of the backlight unit 200. In other words, these light-emitting devices 211 may be arranged in a denser structure in the outer region of the backlight unit 200, so that the display device can display a more uniform luminance in both the central region and the outer region of the backlight unit 200.

[0161] Because the light conversion patterns 216p arranged on the lower surface of the light conversion layer 216 are each arranged at a position corresponding to the light-emitting device 211, the distance between the light conversion patterns 216p arranged in the outer region of the backlight unit 200 may be different from that between the light conversion patterns 216p arranged in its central region.

[0162] As an example, the distance D1 in a first direction of the light conversion patterns 216p arranged in the outer region of the backlight unit 200 may be smaller than the distance D2 in the first direction of the light conversion patterns 216p arranged in its central region. Similarly, the distance D3 in a second direction of the light conversion patterns 216p arranged in the outer region of the backlight unit 200 may be smaller than the distance D4 in the second direction of the light conversion patterns 216p arranged in its central region.

[0163] At this point, the size and thickness of the light conversion patterns 216p arranged in the outer region of the backlight unit 200 may be different from those of the light conversion patterns 216p arranged in the central region of the backlight unit 200.

[0164] As in Fig. 14B, for example, the size S1 of the light conversion patterns 216pe and 216pf arranged in the outer region of the backlight unit 200 may be smaller than the size S2 of the light conversion pattern 216pg arranged in the central region of the backlight unit 200.

[0165] Furthermore, the light conversion patterns 216p may have a multi-layer structure as described above, wherein the thickness of the light conversion patterns 216pe and 216pf arranged in the outer region of the backlight unit 200 or the region of its thickest portion may be smaller than the thickness of the light conversion pattern 216pg arranged in the central region of the backlight unit 200 or the region of its thickest portion.

[0166] In other words, by making the size of the light conversion patterns 216pe and 216pf arranged in the outer region of the backlight unit 200 smaller, the light conversion patterns can be arranged in correspondence with the light-emitting devices 211 arranged at a closer pitch. This consequently makes it possible to prevent the occurrence of a hot spot at the position corresponding to the light-emitting device 211 in the outer region of the backlight unit 200.

[0167] Moreover, the light conversion pattern makes it possible to reduce a blocked level of the light emitted from the light-emitting device 211 in the outer region of the backlight unit 200, thereby increasing the amount of light emission and preventing deterioration of the luminance in the outer region of the backlight unit 200, thus making it possible to display a more uniform luminance over an entire region of the backlight unit 200.

[0168] As described above, by arranging the structure of the light conversion pattern 216p in a different patterned structure for each region of the backlight unit 200, it is possible to prevent deterioration of the luminance in the outer region of the backlight unit 200 and improve the uniformity of the luminance.

[0169] Furthermore, by using the above-mentioned structure of the arrangement of the light conversion patterns 216p, it is possible to prevent the occurrence of hot spots in the backlight unit 200 and improve its luminance uniformity.

[0170] According to various embodiments of the present disclosure, by causing diffraction of the light emitted in the vertical direction of the light-emitting device 211, it is also possible to provide a solution to improve the image quality of the backlight unit 200 and increase its luminous efficiency.

Claims

[1] A backlight unit (200) for a display device, the backlight unit comprising: a substrate (210); a plurality of light-emitting devices (211) arranged on the substrate (210); a light source protection layer (215) disposed on the plurality of light-emitting devices (211), wherein an air gap is disposed between a top surface of the substrate (210) and a bottom surface of the light source protection layer (215) and between the light-emitting devices (211); a light conversion layer (216) disposed on the light source protection layer (215), the light conversion layer (216) comprising a plurality of light conversion patterns (216p) each disposed at positions corresponding to the plurality of light-emitting devices (211); and a phosphor film (217) arranged on the light conversion layer (216), wherein the light source protection layer (215) includes a first resin layer (215r1) covering the light-emitting devices (211) and a transparent film (215p) disposed on the first resin layer (215r1). [2] The backlight unit according to claim 1, wherein a further air gap is arranged between the light conversion layer (216) and the light source protection layer (215). [3] The backlight unit according to claim 1 or 2, wherein the air gap is arranged between the light-emitting devices (211) on the substrate (210). [4] The backlight unit according to claim 1 or 2, further comprising at least one reflector (212) arranged on the substrate (210), wherein the air gap is arranged between a top surface of the reflector (212) and the bottom surface of the light source protection layer (215). [5] The backlight unit of claim 4, wherein the at least one reflector (212) includes a plurality of holes, wherein at least one of the plurality of light-emitting devices (211) is arranged in a hole. [6] The backlight unit according to any preceding claim, wherein the first resin layer (215r1) and the transparent film (215p) are made of the same material and / or have the same density. [7] The backlight unit according to any preceding claim, further comprising a bead layer (215f) disposed on the transparent film (215p), the bead layer (215f) including a first bead and a second bead having different refractive indices. [8] A backlight unit according to any one of claims 5 to 7 when dependent on claim 4, wherein the first resin layer (215r1) is disposed in a hole of the reflector (212) and an upper surface of the first resin layer (215r1) is positioned higher than the upper surface of the reflector (212). [9] A backlight unit according to any one of claims 5 to 8 when dependent on claim 4, wherein the phosphor film (217) includes a first region (A1) and a second region (A2), wherein a distance between the first region (A1) and one of the plurality of light-emitting devices (211) is greater than a distance between the second region (A2) and the one light-emitting device (211), and wherein the air gap is arranged on the upper side of the reflector (212) corresponding to the second region (A2), and / or wherein the light source protective layer (215) includes a pattern with unevenness on an upper surface of the light source protective layer (215) corresponding to the first region (A1), and / or wherein the light source protective layer (215) contains a pattern with unevenness on the underside of the light source protective layer (215) corresponding to the first region (A1), and / or wherein the light source protection layer (215) includes a second resin layer (215r2) disposed on the upper side of the reflector (212) corresponding to the first region (A1). [10] The backlight unit according to claim 9, wherein the second resin layer (215r2) is in direct contact with the transparent film (215p) and the reflector (212) so that no air gap is formed in the region where the second resin layer (215r2) is disposed. [11] The backlight unit according to claim 9 or 10, wherein the second resin layer (215r2) and the transparent film (215p) are made of the same material and / or have the same density. [12] A backlight unit according to any one of the preceding claims, further comprising an optical layer (218) disposed on the phosphor film (217). [13] The backlight unit according to any one of the preceding claims, wherein the light conversion patterns (216p) are configured to adjust an emission direction of the light emitted from the light-emitting device (211). [14] A backlight unit according to any preceding claim, wherein the light conversion patterns (216p) have a central portion having a thickness greater than a thickness of a peripheral portion thereof. [15] A backlight unit according to any one of the preceding claims, wherein the light conversion patterns (216p) are arranged in a region in which an intensity of the light emitted from the light-emitting devices (211) is the strongest. [16] Display device comprising: a scoreboard; and a backlight unit according to any one of the preceding claims.

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