Display device and backlight unit

Abstract

A display device and a backlight unit are provided. The display device includes a display panel, a backlight unit providing light to the display panel, and a conversion sheet between the backlight unit and the display panel. The conversion sheet includes at least one conversion pattern configured such that a top portion of the conversion pattern has a larger area than a bottom portion of the conversion pattern. The at least one conversion pattern includes at least one first conversion layer having a first refractive index and at least one second conversion layer having a second refractive index different from the first refractive index, which are alternately stacked.

Description

Technical Field

[0001] Embodiments relate to a display device and a backlight unit, and more particularly, for example but not limited to, to a display device and a backlight unit capable of shifting a wavelength of blue light harmful to humans to a wavelength of blue light harmless to humans while maintaining the brightness of the blue light. Background Art

[0002] Long-term use of electronic devices including display devices leads to increased exposure to blue light. Increased blue light exposure is associated with adverse human health effects, including dry eyes, sleep disturbances, increased eye fatigue, and visual display terminal (VDT) syndrome. As user awareness and demand for healthcare electronic devices are reconsidered and increased, the development of display devices that can reduce harmful blue light is underway.

[0003] The description provided in this discussion of related art section should not be assumed to be prior art simply because it is mentioned in or associated with the description of the related art section. The discussion of related art section may include information that describes one or more aspects of the subject technology, and the descriptions in this section do not limit the present invention. Summary of the invention

[0004] When a conventional blue light filter layer is used, the brightness of the blue light is reduced or minimized, and a large color change occurs due to the low cut-off characteristic. Therefore, the inventors of the present disclosure have invented a display device that is capable of shifting a blue light wavelength that is harmful to humans to a blue light wavelength that is harmless to humans while maintaining the brightness of the blue light.

[0005] Embodiments may provide a display device including a conversion pattern capable of shifting blue light harmful to humans to blue light harmless to humans.

[0006] Embodiments may provide a display device including blue light quantum dots capable of shifting blue light harmful to humans to blue light harmless to humans and a hollow scatterer.

[0007] An embodiment may provide a display device comprising: a display panel; a backlight unit that provides light to the display panel; and a conversion sheet located between the backlight unit and the display panel, wherein the conversion sheet comprises at least one conversion pattern, the at least one conversion pattern being configured such that a top portion thereof has an area greater than a bottom portion thereof, and the at least one conversion pattern comprising at least one first conversion layer having a first refractive index and at least one second conversion layer having a second refractive index different from the first refractive index that are alternately stacked.

[0008] An embodiment may provide a display device comprising: a display panel; a backlight unit that provides light to the display panel; and a conversion sheet located between the backlight unit and the display panel, wherein the conversion sheet comprises blue light quantum dots, a hollow scatterer, a base layer, and at least one conversion pattern having a refractive index different from that of the base layer, wherein the at least one conversion pattern is configured such that a top portion thereof has an area greater than a bottom portion thereof.

[0009] An embodiment may provide a backlight unit comprising: a plurality of light sources; a light guide plate into which light emitted from the light sources enters; and a prism sheet comprising a prism substrate on the light guide plate and a plurality of prisms on the prism substrate, wherein the prism substrate comprises a first portion having a third refractive index and a second portion having a fourth refractive index that are alternately stacked.

[0010] According to example embodiments, a display device may include a conversion pattern capable of shifting blue light harmful to humans to harmless blue light to reduce or minimize the blue light harmful to humans.

[0011] According to example embodiments, a display device may include blue light quantum dots and hollow scatterers capable of shifting blue light harmful to humans to harmless blue light to reduce or minimize the blue light harmful to humans.

[0012] It is to be understood that both the foregoing general description and the following detailed description of the present disclosure are exemplary and explanatory and are intended to provide further explanation of the disclosure as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] 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:

[0014] Figure 1 shows a configuration of a display device according to an exemplary embodiment;

[0015] Figure 2 shows a configuration of a display device according to another exemplary embodiment;

[0016] Figure 3 shows a cross section of a converter sheet of a display device according to an exemplary embodiment;

[0017] Figure 4 shows a cross section of a converter sheet of a display device according to another exemplary embodiment;

[0018] Figure 5 shows a cross section of a converter sheet of a display device according to yet another exemplary embodiment;

[0019] Figure 6 shows a cross section of a conversion pattern of a converter sheet according to an exemplary embodiment;

[0020] Figure 7 shows a cross section of one of the hollow scatterers of a converter sheet according to an exemplary embodiment;

[0021] Fig. 8A A perspective view showing that the top of a conversion pattern of a conversion sheet according to an exemplary embodiment has a stripe shape;

[0022] Figure 8B A perspective view showing that the top of a conversion pattern of a conversion sheet according to an exemplary embodiment has an island shape;

[0023] Fig. 9 illustrates a cross section of a prism sheet of a backlight unit according to an exemplary embodiment;

[0024] Fig.10 is a graph showing wavelength (nm) and light intensity according to examples and comparative examples; and

[0025] Fig.11 is a graph showing wavelength (nm) and transmittance according to Examples and Comparative Examples.

[0026] Throughout the drawings and detailed description, unless otherwise described, the same reference numerals should be understood to refer to the same elements, features, and structures. The sizes, lengths, and thicknesses of layers, regions, and elements, and descriptions thereof, may be exaggerated for clarity, illustration, and convenience. DETAILED DESCRIPTION

[0027] Reference will now be made in detail to embodiments of the present disclosure, examples of which may be illustrated in the accompanying drawings. The described progression of processing steps and / or operations is an example; however, the order of steps and / or operations is not limited to the order set forth herein, and may be varied as is known in the art, except for steps and / or operations that must occur in a particular order. The names of corresponding elements used in the following description may be selected solely for ease of writing the specification, and therefore may differ from the names used in the actual product.

[0028] In the following description of examples or embodiments of the present disclosure, reference will be made to the accompanying drawings, in which specific examples or embodiments that can be implemented are shown by way of illustration, and in which the same reference numerals and symbols may be used to represent the same or similar parts, even when they are shown in different drawings from each other. In addition, in the following description of examples or embodiments of the present disclosure, when it is determined that the description may make the subject matter in some exemplary embodiments of the present disclosure quite unclear, a detailed description of the well-known functions and components incorporated herein will be omitted. Terms such as "including", "having", "containing", "constituting", "made of" and "formed by..." used herein are generally intended to allow the addition of one or more components, unless such terms are used together with the term "only". As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise.

[0029] Terms such as "first", "second", "A", "B", "(A)", "(B)", "(a)" or "(b)" may be used herein to describe elements of the present disclosure. Each of these terms is not used to define the nature, order, sequence or quantity of the elements, etc., but is only used to distinguish the corresponding element from other elements.

[0030] When it is mentioned that a first element is “connected or coupled to”, “contacts or overlaps”, etc. a second element, it should be interpreted that not only the first element may be “directly connected or coupled to” or “directly contact or overlaps” the second element, but also a third element may be “interposed” between the first element and the second element, or the first element and the second element may be “connected or coupled to”, “contacts or overlaps”, etc. each other via a fourth element. Here, the second element may be included in at least one of two or more elements that are “connected or coupled to”, “contacts or overlaps”, etc. each other.

[0031] When time relative terms such as "after", "subsequently", "next", "before", etc. are used to describe a process or operation of an element or configuration, or a flow or step in an operation, process, or manufacturing method, these terms may be used to describe non-sequential or non-sequential processes or operations unless the terms "directly" or "immediately" are used together.

[0032] Furthermore, when referring to any dimension, relative size, ratio, angle, quantity, etc., the numerical value or corresponding information (e.g., level, range, etc.) of the element or feature should be considered to include a tolerance or error range that may be caused by various factors (e.g., process factors, internal or external influences, noise, etc.), even when no relevant description is specified. In addition, the term "may" fully encompasses all meanings of the term "can".

[0033] Hereinafter, various embodiments will be described in detail with reference to the accompanying drawings.

[0034] Figure 1 A configuration of a display device 10 according to an exemplary embodiment is shown.

[0035] Reference Figure 1 , the display device 10 according to the exemplary embodiment may include, but is not limited to, a backlight unit 100 , a display panel 200 , and a blue light filter layer 300 disposed between the backlight unit 100 and the display panel 200 .

[0036] The backlight unit 100 may include, but is not limited to, a light source 110 providing light to the display panel 200 , a light guide plate 120 disposed on the light source 110 , a prism sheet 130 disposed on the light guide plate 120 , and a diffusion sheet 140 disposed on the prism sheet 130 .

[0037] The light source 110 may provide light which is supplied to the display panel 200 .

[0038] The light source 110 may be, for example, a plurality of light sources.

[0039] The light guide plate 120 having a predetermined thickness may be located on the light source 110 .

[0040] The light guide plate 120 may have, for example, a rectangular shape.

[0041] The material of the light guide plate 120 may be any one of polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), polyethylene naphthalate (PEN), and triacetyl cellulose (CTA) having good transmittance, but is not limited thereto. In addition, other suitable materials having good transmittance are also possible.

[0042] The prism sheet 130 disposed on the light guide plate 120 has a regular array of triangular prisms on a top surface thereof, which can allow light to travel vertically to improve brightness.

[0043] The prism sheet 130 may include a plurality of prisms in, for example, a triangular column shape, but is not limited thereto.

[0044] Each of the plurality of prisms may be shaped such that a width of an upper portion is narrower than a width of a lower portion, but is not limited thereto.

[0045] The prisms can be arranged in a regular array.

[0046] The prism sheet 130 may adjust a path of light supplied from the light source 110 , thereby increasing brightness of the backlight unit 100 .

[0047] For example, Fig. 9 As shown, the prism sheet 130 may include a prism substrate 131 and prisms 132 located on the prism substrate 131 , but is not limited thereto.

[0048] Alternatively, if Fig. 9 As shown, the prism sheet 130 may further include a prism outer portion 133 in addition to the prism base 131 and the prisms 132 , but is not limited thereto.

[0049] When referring to Fig. 9 When described, the prism sheet 130 will be described in more detail.

[0050] The diffusion sheet 140 may diffuse light to provide the light to the display panel 200 .

[0051] The display panel 200 may be disposed on the backlight unit 100 .

[0052] As an example, the display panel 200 may include a liquid crystal layer 220 and a color filter 210 .

[0053] The liquid crystal layer 220 may be disposed on a lower substrate (not shown).

[0054] The color filter 210 may be disposed on an upper substrate (not shown). In some cases, the color filter 210 may be disposed on a lower substrate, and the liquid crystal layer 220 may be located on top of the color filter 210.

[0055] A polarizer (not shown) may be located at the top or bottom of the display panel 200 , but is not limited thereto.

[0056] The polarizer (not shown) may be a horizontal polarizer or a vertical polarizer, but is not limited thereto.

[0057] As an example, the color filter 210 may include a plurality of color filters, such as a first color filter 211, a second color filter 212, and a third color filter 213. In addition, other suitable numbers of color filters are also possible.

[0058] In an example, the first color filter 211 may be a red color filter, the second color filter 212 may be a green color filter, and the third color filter 213 may be a blue color filter, but the present disclosure is not limited thereto. Alternatively, each of the first color filter, the second color filter, and the third color filter may be configured as other color filters (e.g., white, cyan, magenta, or yellow, etc.).

[0059] The blue light filter layer 300 may include a dye (or pigment) and a binder.

[0060] The dye (or pigment) used in the blue light filter layer 300 may be a yellow colorant, but is not limited thereto.

[0061] The blue light filter layer 300 can reduce or minimize the intensity of dangerous blue light that is harmful to humans by cutting off the wavelength range of dangerous blue light. As an example, the blue light filter layer 300 can reduce or minimize the intensity of dangerous blue light that is harmful to humans by cutting off 415nm to 455nm, which is the wavelength range of dangerous blue light, but is not limited thereto. As used herein, the term "cut off" can be interpreted as blocking energy or light.

[0062] Alternatively, Figure 2 Exemplary embodiments of the present invention may provide a conversion sheet 400 that can improve color gamut and brightness and block dangerous blue light that is harmful to humans.

[0063] Figure 2 A configuration of a display device 10 according to another exemplary embodiment is shown.

[0064] Figure 3 A cross section of a converter sheet 400 of a display device 10 according to an exemplary embodiment is shown.

[0065] Reference Figure 2 , the display device 10 according to the exemplary embodiment may include, but is not limited to, a backlight unit 100, a display panel 200, and a conversion sheet 400 disposed between the backlight unit 100 and the display panel 200. Figure 2 In the display device 10 shown in FIG. Figure 1 Substantially the same components are denoted by the same reference numerals, and a detailed description thereof will be omitted or given briefly.

[0066] The conversion sheet 400 can shift the wavelength range of blue light harmful to humans to blue light having a different wavelength range that is harmless to humans without reducing brightness. As an example, the conversion sheet 400 can shift 415nm to 455nm (i.e., the wavelength range of blue light harmful to humans) to blue light having a different wavelength range that is harmless to humans without reducing brightness, but is not limited thereto.

[0067] Reference Figure 3 , the conversion sheet 400 of the display device 10 according to the exemplary embodiment may include at least one conversion pattern 410 , a base layer 420 , blue light quantum dots 430 , a hollow scatterer 440 , and the like.

[0068] Blue light quantum dots 430 and hollow scatterers 440 may be dispersed in the base layer 420 .

[0069] In the at least one conversion pattern 410 , an area of ​​a top portion may be greater than an area of ​​a bottom portion, but is not limited thereto.

[0070] The cross section of at least one conversion pattern 410 may be an inverted trapezoid, such as Figure 3Alternatively, the cross section of at least one conversion pattern 410 may be an inverted triangle, and include any shape in which the area of ​​the top is larger than the area of ​​the bottom.

[0071] The at least one conversion pattern 410 may be disposed to be spaced apart from each other, but is not limited thereto.

[0072] When the conversion patterns 410 are spaced apart from each other, light ① vertically emitted from the light source 110 can propagate to the display panel 200 through the base layer 420 without passing through the conversion patterns 410, so that the path of the light does not change. As a result, the brightness of the light can be prevented from being reduced.

[0073] The height of the conversion pattern 410 may be equal to or lower than the height of the conversion sheet 400. For example, the height of the conversion pattern 410 may be 500 μm or less.

[0074] The base layer 420 may be formed of a transparent polymer, but is not limited thereto.

[0075] The blue light quantum dots 430 and the hollow scatterers 440 may be dispersed on the base layer 420 .

[0076] The blue light quantum dot 430 may be a quantum dot that emits blue light. The emission wavelength of the blue light quantum dot 430 may preferably be in the range of 460 nm to 500 nm, but is not limited thereto.

[0077] On the other hand, the wavelength band of blue light harmful to humans may be within the range of 415 nm to 455 nm, but is not limited thereto.

[0078] A Stokes shift of 5 nm to 10 nm is desired to minimize the ratio of harmless blue light (460 nm to 500 nm) to harmful blue light (415 nm to 455 nm).

[0079] As an example, each blue light quantum dot 430 may include a core 431 and a shell 432 disposed to surround the core 431. Figure 3 4 shows blue light quantum dots 430 each having a structure consisting of a core 431 and a shell 432, but the blue light quantum dot 430 of the present disclosure is not limited to a quantum dot having such a heterogeneous structure and may have a single structure.

[0080] exist Figure 3 , the blue light quantum dot 430 is shown to have a spherical shape, but is not limited thereto, and may have the shape of a pyramidal particle, a multi-arm particle, or a cubic particle, such as a nanoparticle, a nanotube, a nanowire, a nanofiber, or a nanoplatelet.

[0081] When each blue light quantum dot 430 has a structure consisting of a core 431 and a shell 432, the core 431 is basically the part where light emission occurs. The light emission wavelength of the blue light quantum dot is determined by the size of the core 431. In order to receive the quantum confinement effect, the size of the core 431 is generally smaller than the exciton Bohr radius according to the material, and may have an optical band gap at the corresponding size.

[0082] The blue light quantum dots 430 may be semiconductor nanocrystals or metal oxide particles with quantum confinement effect. For example, the blue light quantum dots 430 may include but are not limited to nano semiconductor compounds of II-VI, I-III-VI or III-V groups, but are not limited thereto.

[0083] More specifically, the core 431 and / or the shell 432 of each blue light quantum dot 430 may be a nanocrystal having a core-shell structure, including: Group II to Group VI compound semiconductor nanocrystals such as CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HqS, HgTe and / or combinations thereof; Group III to Group V or Group V such as GaP, GaAs, GaSb, InP, InAs and / or InSb; PbS, PbSe, PbTe and / or combinations thereof. Group IV to Group VI compound semiconductor nanocrystals; nanocrystals such as AgGaS2, AgGaSe2, AgGaTe2, CuInS2, CuInSe2, CuGaS2 and / or CuGaSe2; metal oxide nanoparticles such as ZnO, TiO2 and / or combinations thereof; nanocrystals such as CdSe / ZnSe, CdS / ZnS, ZnSe / ZnS, InP / ZnSZnO / MgO and / or combinations thereof, but not limited thereto. The semiconductor nanoparticles may be doped or undoped with rare earth elements such as Eu, Er, Tb, Tm, Dy or combinations thereof, or doped with transition metal elements such as Mn, Cu, Ag, Al or combinations thereof, but not limited thereto. For example, the core 431 of the blue light quantum dot 430 may be selected from ZnSe, ZnTe, CdSe, CdTe, InP, ZnCdS, Cu x ln 1-x S, Cu x In 1-x Se, Ag x ln 1-x The group consisting of S and combinations thereof, but not limited thereto.

[0084] In addition, the shell 432 of each blue light quantum dot 430 can be selected from ZnS, GaP, CdS, ZnSe, CdS / ZnS, ZnSe / ZnS, ZnS / ZnSe / CdSe, GaP / ZnS, CdS / CdZnS / ZnS, ZnS / CdSZnS, CdS / CdS, CdS / CdZnS / ZnS, CdS / CdS ... x Zn1-x S and combinations thereof, but not limited thereto. The blue light quantum dot 430 may also be an alloy quantum dot (QD) (e.g., CdS x Se 1-x 、CdSe x Te 1-x or Zn x Cd 1-x Se), such as homogeneous alloy QDs or gradient alloy QDs, but not limited thereto.

[0085] Alternatively, each of the blue light quantum dots 430 may further include a ligand 433 in a structure consisting of a core 431 and / or a shell 432 .

[0086] The ligand 433 may be bonded to the surface of the shell 432 of the blue light quantum dot 430 and contained in the blue light quantum dot 430. The ligand 433 may improve the dispersibility of the blue light quantum dot 430 in the base layer 420.

[0087] The hollow scatterers 440 are particles for internal scattering, which can maximize the luminous efficiency of the blue light quantum dots 430 .

[0088] The size of the hollow scatterer 440 may be, but is not limited to, 500 nm to 2000 nm.

[0089] The hollow scatterers 440 may be transparent conductive oxide (TCO) particles, particularly TiO 2 particles, but are not limited thereto.

[0090] Each hollow diffuser 440 has a cavity therein to reduce or minimize transmittance due to its geometric characteristics.

[0091] A plurality of blue light quantum dots 430 and a plurality of hollow scatterers 440 may be dispersed in the base layer 420. The mixing of the blue light quantum dots 430 and the hollow scatterers 440 in the base layer 420 may maximize the luminous efficiency of the blue light quantum dots 430.

[0092] The number of blue light quantum dots 430 and the number of hollow scatterers 440 may be the same or different. Specifically, when the number of blue light quantum dots 430 is different from the number of hollow scatterers 440, the number of hollow scatterers 440 may be greater than the number of blue light quantum dots 430, but is not limited thereto. More specifically, the ratio of the number of blue light quantum dots to the number of hollow scatterers may be 1:10, but is not limited thereto.

[0093] In the conversion sheet 400 , the refractive index of the base layer 420 is different from the refractive index of the at least one conversion pattern 410 , but is not limited thereto.

[0094] As an example, the refractive index of the base layer 420 may be greater than the refractive index of the at least one conversion pattern 410 .

[0095] Because the refractive index of the base layer 420 is greater than the refractive index of at least one conversion pattern 410, when light ② from the light source 110 enters the conversion pattern 410 from the base layer 420, the refraction angle is greater than the incident angle, which can change the path of the light toward the display panel 200. In addition, light ① vertically emitted from the light source 110 can propagate through the base layer 420 to the display panel 200 without passing through the conversion pattern 410, so that the path of the light is not changed.

[0096] The light path may be redirected toward the display panel 200 to prevent a reduction in brightness.

[0097] The refractive index of the base layer may be greater than or equal to 1.8, and the refractive index of the at least one conversion pattern may be less than 1.8, but the present disclosure is not limited thereto.

[0098] Figure 4 A cross section of a converter sheet 400 of a display device according to another exemplary embodiment is shown.

[0099] Reference Figure 4 , a conversion sheet 400 of a display device 10 according to another exemplary embodiment may include at least one conversion pattern 410 and a base layer 420. Figure 4 In the converter sheet 400 shown in FIG. Figure 3 Substantially the same components are denoted by the same reference numerals, and a detailed description thereof will be omitted or given briefly.

[0100] Base layer 420 can be compared with reference Figure 3 The described base layer 420 is substantially the same, and a detailed description thereof will be omitted or given briefly.

[0101] The at least one conversion pattern 410 may be configured such that an area of ​​a top portion is greater than an area of ​​a bottom portion, but is not limited thereto.

[0102] The cross-sectional shape of at least one conversion pattern 410 may be similar to the reference Figure 3 The cross-sectional shape of the at least one conversion pattern 410 described is substantially the same, and a detailed description thereof will be omitted or briefly given.

[0103] At least one conversion pattern 410 may have a multi-layer structure. As an example, at least one conversion pattern 410 may include at least one first conversion layer 411 having a first refractive index and at least one second conversion layer 412 having a second refractive index different from the first refractive index, the first conversion layers 411 and the second conversion layers 412 being alternated.

[0104] The first conversion layer 411 may be located at an end of at least one conversion pattern 410 , and the first refractive index may be greater than the second refractive index, but is not limited thereto. Alternatively, the second conversion layer 412 may be located at an end of at least one conversion pattern 410 .

[0105] The term "end" as used herein refers to the upper end and / or the lower end.

[0106] exist Figure 4 In the embodiment, the end portion in the conversion pattern 410 is disposed from the first conversion layer 411 , but is not necessarily limited thereto, and may be disposed from the second conversion layer 412 .

[0107] The first refractive index may be greater than or equal to 1.6 and the second refractive index may be less than or equal to 1.4, but are not limited thereto.

[0108] At least one of the first conversion layer 411 or the second conversion layer 412 may be, but is not limited to, two or more layers.

[0109] When at least one of the first conversion layer 411 or the second conversion layer 412 is two or more layers, the minimum number of layers of the first conversion layer 411 and the second conversion layer 412 may be three or more layers, but is not limited thereto.

[0110] Specifically, the number of layers of the first conversion layer 411 and the second conversion layer 412 may be 5 or more, but is not limited thereto.

[0111] When the number of layers of the first conversion layer 411 and the second conversion layer 412 is 5 or more, blue light harmful to humans can be efficiently cut off.

[0112] More specifically, the cutoff characteristic may be adjusted according to the thickness and the total number of layers of each of the first conversion layer 411 and the second conversion layer 412 .

[0113] When each of the first conversion layer 411 and the second conversion layer 412 is two or more layers, the thickness of the thickest layer of the two or more first conversion layers and the thickness of the thickest layer of the two or more second conversion layers may each be 5 μm or less, but is not limited thereto.

[0114] When the thickness of each of the first conversion layer 411 and the second conversion layer 412 is 5 μm or less, the conversion pattern 410 having more first conversion layers or second conversion layers of the same height as the conversion pattern 410 may be manufactured.

[0115] In the conversion plate 400 , in order of increasing refractive index, the refractive index of the base layer 420 may be the largest, followed by the first refractive index of the first conversion layer 411 , and the second refractive index of the second conversion layer 412 .

[0116] As an example, the refractive index of the base layer 420 may be greater than or equal to 1.8, the first refractive index of the first conversion layer 411 may be greater than or equal to 1.6 and less than or equal to 1.8, and the second refractive index of the second conversion layer 412 may be less than or equal to 1.4, but the present disclosure is not limited thereto.

[0117] When the refractive index of the base layer, the first refractive index of the first conversion layer, and the second refractive index of the second conversion layer satisfy the above values, blue light harmful to humans can be effectively cut off while preventing the brightness of the blue light from decreasing.

[0118] Figure 5 FIG. 4 shows a cross section of a converter sheet 400 of a display device 10 according to yet another exemplary embodiment. Figure 5 In the converter sheet 400 shown in FIG. Figure 4 Substantially the same components are denoted by the same reference numerals, and a detailed description thereof will be omitted or given briefly.

[0119] Reference Figure 5 , Figure 4 The conversion sheet 400 may further include blue light quantum dots 430 and hollow scatterers 440 .

[0120] Figure 5 The blue light quantum dots 430 and the hollow scatterers 440 can be compared with the reference Figure 3 The described blue light quantum dots 430 and hollow scatterers 440 are substantially the same, and a detailed description thereof will be omitted or briefly given.

[0121] when Figure 4 When the base layer 420 further includes blue light quantum dots 430 and hollow scatterers 440, as in Figure 5 In the case of the conversion sheet 400, the conversion pattern 410 can effectively cut off the blue light harmful to humans while preventing the brightness from being reduced, and shift the blue light harmful to humans to the blue light harmless to humans through the Stokes shift.

[0122] also, Figure 5 The conversion sheet 400 can prevent color change due to high cutoff.

[0123] Referenced above Figures 3 to 5 Various modifications of the conversion plate 400 are described. Figure 6 and Figure 7 The conversion pattern 410 and the hollow scatterer 440 of the conversion sheet 400 are described.

[0124] Figure 6 A cross section of a conversion pattern 410 of a converter sheet 400 according to an exemplary embodiment is shown.

[0125] The conversion pattern 410 may have a multi-layer structure including, but not limited to, alternately stacked first conversion layers 411 having a first refractive index and second conversion layers 412 having a second refractive index different from the first refractive index.

[0126] In the conversion pattern 410 , the number of layers of the first conversion layer 411 and the second conversion layer 412 may be, but is not limited to, five layers.

[0127] The conversion pattern 410 may be configured such that one layer of the first conversion layers 411 is located at an end of the conversion pattern, but is not limited thereto. Alternatively, one layer of the second conversion layers 412 may be located at an end of the conversion pattern.

[0128] The height H1 of each layer in the first conversion layer 411 and the height H2 of each layer in the second conversion layer 412 may be the same or different.

[0129] The heights of the first conversion layers 411 within the conversion patterns 410 may be different from each other. Specifically, the height H1 of the first conversion layer 411 may be 5 μm or less, but is not limited thereto.

[0130] In addition, the heights of the second conversion layers 412 in the conversion patterns 410 may be different from each other. In particular, the height H2 of the second conversion layer 412 may be 5 μm or less, but is not limited thereto.

[0131] The area S1 of the top of the conversion pattern 410 may be greater than the area S2 of the bottom, but is not limited thereto.

[0132] Figure 7 A cross section of one of the hollow scatterers 440 of the converter sheet 400 according to an exemplary embodiment is shown.

[0133] Reference Figure 7 Each hollow diffuser 440 has a cavity volume 2×D2 which is a value obtained by subtracting twice the thickness of the hollow diffuser 440 from the diameter D1 of the hollow diffuser 440 to reduce or minimize the transmittance of the hollow diffuser 440 .

[0134] The diameter D1 of each hollow scatterer 440 may be, but is not limited to, 500 nm to 2000 nm.

[0135] The thickness (D2) of each hollow scatterer 440 may be, but is not limited to, 50 nm to 200 nm.

[0136] Materials and references of hollow diffuser 440 Figure 3 The hollow diffusers 440 described are substantially the same. The hollow diffusers 440 may be transparent conductive oxide (TCO) particles, particularly TiO2 particles, but are not limited thereto.

[0137] exist Figure 7, the hollow scatterer 440 is shown to have a spherical shape, but is not limited thereto, and may have the shape of a conical particle, a multi-arm particle, or a cubic particle, such as a nanoparticle, a nanotube, a nanowire, a nanofiber, or a nanoplatelet.

[0138] Referenced above Figure 6 and Figure 7 The conversion pattern 410 and the hollow scatterer 440 of the conversion plate 400 are described. Fig. 8A and Figure 8B The geometry of the top portion of the conversion pattern 410 of the converter sheet 400 is described.

[0139] Fig. 8A A perspective view showing that the top of a conversion pattern 410 of a conversion sheet 400 according to an exemplary embodiment has a stripe shape.

[0140] Reference Fig. 8A , the conversion patterns 410 in the conversion sheet 400 are arranged in the form of partitions so as to be spaced apart from each other, so that when viewed in a top view, the top of the conversion pattern 410 may appear in the form of a strip, but is not limited thereto. Alternatively, as Figure 8B As shown, when viewed in a top view, the top of the conversion pattern 410 may appear in the form of an island.

[0141] The conversion pattern 410 of the conversion sheet 400 may be configured such that an area of ​​a top portion is larger than an area of ​​a bottom portion, but is not limited thereto.

[0142] Figure 8B A perspective view showing that the top of a conversion pattern 410 of a conversion sheet 400 according to an exemplary embodiment has an island shape.

[0143] Reference Figure 8B , when viewed in a plan view, the top of the conversion pattern 410 in the conversion sheet 400 may appear in the form of an island, but is not limited thereto.

[0144] The top portion of the conversion pattern 410 is Fig. 8A and Figure 8B It is shown as a stripe or island shape, but is not limited thereto, and may be a diagonal line shape or a grid shape.

[0145] The conversion pattern 410 is Fig. 8A and Figure 8B , so that its top and bottom have the same shape, but not limited thereto, and the top and bottom may have different shapes. For example, when the top and bottom have different shapes, the top may have a circular shape, and the bottom may have an elliptical shape. In another example, the top may have a polygonal shape, and the bottom may have a circular shape.

[0146] In the above, the conversion sheet 400 for cutting off dangerous blue light has been described. The prism sheet 130 will be described below, which may have the same or similar function as the conversion sheet 400.

[0147] Fig. 9 A cross section of a prism sheet 130 of a backlight unit 100 according to an exemplary embodiment is shown.

[0148] The prism sheet 130 may be Figure 1 The prism sheet 130 described is substantially the same.

[0149] Reference Fig. 9 , the prism sheet 130 can be Example 1, Example 2, or Example 3.

[0150] Referring to Example 1, the prism sheet 130 may include a prism substrate 131 and a plurality of prisms 132 on the prism substrate 131 .

[0151] The prism base 131 may be located on the light guide plate 120 .

[0152] The prism substrate 131 may include first portions 131 a and second portions 131 b that are alternately stacked, the first portions 131 a having a third refractive index, and the second portions 131 b having a fourth refractive index different from the third refractive index.

[0153] The third refractive index can be compared with the reference Figure 4 The first refractive index of the first conversion layer described is substantially the same, and the fourth refractive index may be the same as that of the reference Figure 4 The second refractive index of the second conversion layer described is substantially the same, but the present disclosure is not limited thereto. In this case, the third refractive index may be greater than or equal to 1.6, and the fourth refractive index may be less than or equal to 1.4, but is not limited thereto. Such refractive indices may have different values.

[0154] The material of the first portion 131a can be the same as that of the reference Figure 4 The material of the first conversion layer 411 described above is substantially the same, and the material of the second portion 131b may be the same as that of the reference Figure 4 The material of the second conversion layer 412 described above is substantially the same, but the present disclosure is not limited thereto. In addition, the first portion 131a and the second portion 131b may include the same Figure 4 The materials described are different materials.

[0155] When the prism substrate 131 has a structure in which first portions 131a having a third refractive index and second portions 131b having a fourth refractive index different from the third refractive index are alternately stacked, the prism substrate 131 can effectively cut off dangerous blue light (e.g., 415nm to 455nm) that is harmful to humans.

[0156] The prism substrate 131 shown in Example 2, which is substantially the same as the prism substrate 131 shown in Example 1, is denoted by the same reference numerals, and a detailed description thereof will be omitted or briefly given. Referring to Example 2, each of the plurality of prisms 132 may include a first portion 132a and a second portion 132b alternately stacked, the first portion 132a having a third refractive index, and the second portion 132b having a fourth refractive index different from the third refractive index.

[0157] The material of the first portion 132a can be the same as that of the reference Figure 4 The material of the first conversion layer 411 described above is substantially the same, and the material of the second portion 132b may be the same as that of the reference Figure 4 The material of the second conversion layer 412 described above is substantially the same, but the present disclosure is not limited thereto. In addition, the first portion 132a and the second portion 132b may include the same Figure 4 The materials described are different materials.

[0158] Referring to Example 3, the prism sheet 130 of Example 3 may further include a prism outer portion 133 in addition to the prism base 131 and the prisms 132. In the prism sheet 130 shown in Example 3, components substantially the same as those in Example 1 are denoted by the same reference numerals, and detailed descriptions thereof will be omitted or briefly given.

[0159] The prism outer 133 may be located on the light guide plate 120 , and may be disposed on at least some areas of the prism 132 .

[0160] The prism outer portion 133 may include first portions 133 a and second portions 133 b that are alternately stacked, the first portions 133 a having a third refractive index, and the second portions 133 b having a fourth refractive index different from the third refractive index.

[0161] The material of the first portion 133a can be the same as that of the reference Figure 4 The material of the first conversion layer 411 described above is substantially the same, and the material of the second portion 133b may be the same as that of the reference Figure 4 The material of the second conversion layer 412 described above is substantially the same, but the present disclosure is not limited thereto. The first portion 133a and the second portion 133b may include the same Figure 4 The materials described are different materials.

[0162] When the prism sheet 130 is according to Example 2 or Example 3, the effect of the prism sheet 130 may be substantially the same as that of the prism sheet 130 of Example 1.

[0163] Fig. 9 The prism sheet 130 shown can be used for Figure 1 and Figure 2When the prism substrate 131 is provided as in Example 1, Example 2, or Example 3 and the conversion sheet 400 is provided between the backlight unit 100 and the display panel 200, dangerous blue light harmful to humans can be cut off more effectively.

[0164] The prism sheet 130 is Fig. 9 2 is shown as having a single layer, but is not limited thereto, and may be provided with multiple layers.

[0165] In other words, the prism sheet 130 may be, but is not necessarily limited to, a multi-layer, and may be disposed between the light guide plate 120 and the diffusion sheet 140 .

[0166] When the prism sheet 130 includes a plurality of layers, one of Example 1, Example 2, and Example 3 may be located on each layer, but is not limited thereto.

[0167] In one example, when the prism sheet 130 has two layers, Example 1 and Example 2 may be located on the two layers, respectively, but is not limited thereto.

[0168] In another example, when the prism sheet 130 has two layers, Example 1 may be located on both layers, but is not limited thereto. Alternatively, when the prism sheet 130 has two layers, Example 2 may be located on both layers, but is not limited thereto. Furthermore, when the prism sheet 130 has two layers, Example 3 may be located on both layers, but is not limited thereto.

[0169] According to the thickness of each layer of the prism sheet 130 and the total number of layers, the characteristic of cutting off blue light harmful to humans may be adjusted.

[0170] I. Measurement of Stokes shift, dangerous blue ratio and brightness efficiency

[0171] Table 1 below shows the wavelength λ at which the intensity of blue light measured from the display device according to Comparative Example 1, Comparative Example 2 and Example is maximized. max (nm), dangerous blue ratio (%), CIE xyY and luminous efficiency (%).

[0172] Comparative Example 1 is a display device without using a conversion plate or a blue light filter layer.

[0173] Comparative Example 2 is a display device having a blue light filter layer 300 disposed between the backlight unit 100 and the display panel 200. Figure 1 shown.

[0174] An example is a display device having a conversion sheet 400 disposed between a backlight unit 100 and a display panel 200, such as Figure 2 shown.

[0175] The dangerous blue ratio (%) and the luminous efficiency (%) were analyzed by the following method.

[0176] 1. Dangerous blue ratio (%) = {definite integral value of light intensity as a continuous function in the closed interval (415nm, 455nm) / definite integral value of light intensity as a continuous function in the closed interval (400nm, 500nm)} x 100 (%)}

[0177] 2. Brightness efficiency (%) = (brightness / brightness of comparative example 1) x 100 (%)

[0178] [Table 1]

[0179]

[0180] Referring to Table 1, it can be seen that when the blue light filter layer is used as in Comparative Example 2, the wavelength at which the blue light has the maximum intensity is the same as in Comparative Example 1, and no Stokes shift occurs.

[0181] In contrast, the example shows that a Stokes shift has occurred and the blue light has a wavelength λ of maximum intensity. max Shifted by 5nm.

[0182] Reference Fig.10 , it can be seen that, compared with the comparative examples (ie, comparative example 1 and comparative example 2), Stokes shift has occurred in the example.

[0183] Furthermore, comparing Comparative Example 1, Comparative Example 2, and Example, it can be seen that the dangerous blue ratio, which is the percentage of blue light harmful to humans, has been reduced from 36.8% to 19.5% or 11.5%.

[0184] This shows that Comparative Example 2 ( Figure 1 ) and examples of blue light filtering layers (such as Figure 2 The conversion film (shown) is effective in reducing blue light that is harmful to humans.

[0185] In addition, since the example has a Figure 1 ) has a lower dangerous blue ratio, so it can be seen that the example (such as Figure 2 The effect of the conversion film of Example 2 (as shown) on reducing blue light harmful to humans is greater than that of Comparative Example 2 (as shown Figure 1 A blue light filter layer is shown.

[0186] Furthermore, when Comparative Example 1, Comparative Example 2, and Example are compared in the CIE xyY color space, it can be seen that, unlike Comparative Example 1, Comparative Example 2 has color variations due to different y and Y values.

[0187] In contrast, when Comparative Example 1 and Example are compared, it can be seen that the values ​​of x, y, and Y in CIE xyY are substantially the same, and there is almost no color change.

[0188] The result of almost no color shift indicates that the color reproduction efficiency has been improved.

[0189] With respect to luminance efficiency, Comparative Example 2 shows that luminance is significantly reduced.

[0190] In contrast, compared with Comparative Example 2, Example 2 shows a slight decrease in brightness.

[0191] Therefore, exemplary embodiments of the present disclosure provide a display device capable of shifting a wavelength of blue light harmful to humans to a wavelength of blue light harmless to humans while maintaining the brightness of the blue light.

[0192] II. Cut-off measurement

[0193] Table 2 below shows the results of measuring T90-T10 of the display devices according to Comparative Example 2 and the example to compare the cutoff characteristics of blue light harmful to humans.

[0194] T90-T10 = wavelength at 90% transmittance - wavelength at 10% transmittance (nm)

[0195] [Table 2]

[0196] <![CDATA[λ(T 90 -T 10 )(nm)]]> Comparative Example 2 32 Example 5

[0197] When comparing Comparative Example 2 and Example as shown in Table 2 above, it can be seen that Comparative Example 2 has a larger T90-T10 value of 32 nm, while Example has a smaller value of 5 nm.

[0198] Reference Fig.11 , it can be seen that the transmittance of the comparative example (ie, comparative example 2 in Table 2) decreases moderately from 90% to 10%, while that of the example decreases sharply from 90% to 10%.

[0199] These results show that the transmittance of the example sharply decreases around 455 nm, which is the upper limit of blue light harmful to humans, and thus blue light (eg, 415 nm to 455 nm) harmful to humans can be efficiently cut off.

[0200] In contrast, it can be seen that the comparative example cannot effectively cut off blue light that is harmful to humans.

[0201] Therefore, in the display device according to the exemplary embodiment of the present disclosure, dangerous blue light that is harmful to humans may be cut off more effectively.

[0202] The above-mentioned embodiment will be briefly described below.

[0203] A display device according to an exemplary embodiment includes: a display panel; a backlight unit that provides light to the display panel; and a conversion sheet located between the backlight unit and the display panel, wherein the conversion sheet includes at least one conversion pattern, the at least one conversion pattern is configured so that a top portion of the conversion pattern has a larger area than a bottom portion of the conversion pattern, and the at least one conversion pattern includes at least one first conversion layer having a first refractive index and at least one second conversion layer having a second refractive index different from the first refractive index that are alternately stacked.

[0204] The at least one first conversion layer may be located at an end of the at least one conversion pattern, and the first refractive index may be greater than the second refractive index.

[0205] The first refractive index may be greater than or equal to 1.6, and the second refractive index may be less than or equal to 1.4.

[0206] At least one of the first conversion layer or the second conversion layer may include two or more conversion layers.

[0207] Each of the thickness of the thickest first conversion layer among the two or more first conversion layers and the thickness of the thickest second conversion layer among the two or more second conversion layers may be 5 μm or less.

[0208] The backlight unit may include: a plurality of light sources; a light guide plate into which light emitted from the light sources enters; and a prism sheet including a prism substrate on the light guide plate and a plurality of prisms on the prism substrate, wherein the prism substrate includes a first portion having a third refractive index and a second portion having a fourth refractive index that are alternately stacked.

[0209] The prism sheet may include a plurality of prisms in a triangular column shape.

[0210] The backlight unit may further include a diffusion sheet disposed on the prism sheet.

[0211] The converter may also include blue light quantum dots and hollow scatterers.

[0212] The conversion sheet may further include a base layer, and the blue light quantum dots and the hollow scatterers are dispersed in the base layer.

[0213] The number of hollow scatterers can be greater than the number of blue light quantum dots.

[0214] Each of the blue light quantum dots may include a core, a shell, and a ligand bound to a surface of the shell.

[0215] A top portion of at least one conversion pattern may have a stripe shape.

[0216] A top of at least one conversion pattern may have an island shape.

[0217] At least one conversion pattern may be disposed to be spaced apart from each other.

[0218] A display device according to an exemplary embodiment includes: a display panel; a backlight unit that provides light to the display panel; and a conversion sheet located between the backlight unit and the display panel, wherein the conversion sheet includes blue light quantum dots, a hollow scatterer, a base layer, and at least one conversion pattern having a second refractive index different from a first refractive index of the base layer, wherein at least one conversion pattern is configured so that its top has an area greater than its bottom.

[0219] The first refractive index of the base layer may be greater than the second refractive index of the at least one conversion pattern.

[0220] The first refractive index of the base layer may be greater than or equal to 1.8, and the second refractive index of the at least one conversion pattern may be less than 1.8.

[0221] The backlight unit may include: a plurality of light sources; a light guide plate into which light emitted from the light sources enters; and a prism sheet including a prism substrate on the light guide plate and a plurality of prisms on the prism substrate, wherein the prism substrate includes a first portion having a third refractive index and a second portion having a fourth refractive index that are alternately stacked.

[0222] Each of the plurality of prisms may include a first portion having a third refractive index and a second portion having a fourth refractive index different from the third refractive index, which are alternately stacked.

[0223] The number of hollow scatterers can be greater than the number of blue light quantum dots.

[0224] A top portion of at least one conversion pattern may have a stripe shape.

[0225] A top of at least one conversion pattern may have an island shape.

[0226] According to an exemplary embodiment, a backlight unit includes: a plurality of light sources; a light guide plate into which light emitted from the light sources enters; and a prism sheet including a prism substrate on the light guide plate and a plurality of prisms on the prism substrate, wherein the prism substrate includes a first portion having a third refractive index and a second portion having a fourth refractive index that are alternately stacked.

[0227] Each of the prisms may include alternately stacked first portions having a third refractive index and second portions having a fourth refractive index different from the third refractive index.

[0228] The backlight unit may further include a prism outer portion on the light guide plate and disposed on at least some areas of the prism, wherein the prism outer portion includes alternately stacked first portions having a third refractive index and second portions having a fourth refractive index different from the third refractive index.

[0229] The above description has been presented to enable any person skilled in the art to make and use the technical concepts of the present disclosure, and has been provided in the context of specific applications and their requirements. Various modifications, additions and substitutions to the described embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. The above description and accompanying drawings provide examples of the technical concepts of the present disclosure for illustrative purposes only. That is, the disclosed embodiments are intended to illustrate the scope of the technical concepts of the present disclosure.

[0230] CROSS-REFERENCE TO RELATED APPLICATIONS

[0231] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0120678, filed on September 11, 2023, which is hereby incorporated by reference in its entirety for all purposes as if fully set forth herein.

Claims

1. A display device, comprising: Display panel; a backlight unit, the backlight unit providing light to the display panel; as well as a conversion sheet, the conversion sheet being located between the backlight unit and the display panel, The conversion sheet includes at least one conversion pattern, and the at least one conversion pattern is configured such that a top portion of the conversion pattern has a larger area than a bottom portion of the conversion pattern, and The at least one conversion pattern includes at least one first conversion layer having a first refractive index and at least one second conversion layer having a second refractive index different from the first refractive index, which are alternately stacked.

2. The display device according to claim 1, wherein: The at least one first conversion layer is located at an end of the at least one conversion pattern, and the first refractive index is greater than the second refractive index.

3. The display device according to claim 1, wherein: The first refractive index is greater than or equal to 1.6, and the second refractive index is less than or equal to 1.

4.

4. The display device according to claim 1, wherein: At least one of the first conversion layer or the second conversion layer includes two or more conversion layers.

5. The display device according to claim 4, wherein: Each of the thickness of the thickest first conversion layer among the two or more first conversion layers and the thickness of the thickest second conversion layer among the two or more second conversion layers is 5 μm or less.

6. The display device according to claim 1, wherein: The backlight unit comprises: Multiple light sources; a light guide plate into which light emitted from the light source enters; and a prism sheet, the prism sheet comprising a prism base located on the light guide plate and a plurality of prisms located on the prism base, The prism substrate includes a first portion having a third refractive index and a second portion having a fourth refractive index which are alternately stacked.

7. The display device according to claim 6, wherein: The prism sheet includes the plurality of prisms in a triangular column shape.

8. The display device according to claim 6, wherein: The backlight unit further includes a diffusion sheet disposed on the prism sheet.

9. The display device according to claim 1, wherein: The conversion plate also includes blue light quantum dots and hollow scatterers.

10. The display device according to claim 9, wherein: The conversion plate further includes a base layer, and the blue light quantum dots and the hollow scatterers are dispersed in the base layer.

11. The display device according to claim 9, wherein: The number of the hollow scatterers is greater than the number of the blue light quantum dots.

12. The display device according to claim 9, wherein: Each of the blue light quantum dots includes a core, a shell, and a ligand bonded to a surface of the shell.

13. The display device according to claim 1, wherein: A top portion of the at least one conversion pattern has a stripe shape.

14. The display device according to claim 1, wherein: A top portion of the at least one conversion pattern has an island shape.

15. The display device according to claim 1, wherein: The at least one conversion pattern is disposed to be spaced apart from each other.

16. A display device, comprising: Display panel; a backlight unit, the backlight unit providing light to the display panel; as well as a conversion sheet, the conversion sheet being located between the backlight unit and the display panel, The conversion sheet includes blue light quantum dots, hollow scatterers, a base layer, and at least one conversion pattern having a second refractive index different from a first refractive index of the base layer. The at least one conversion pattern is configured such that a top portion of the conversion pattern has a larger area than a bottom portion of the conversion pattern.

17. The display device according to claim 16, wherein: The first refractive index of the base layer is greater than the second refractive index of the at least one conversion pattern.

18. The display device according to claim 16, wherein: The first refractive index of the base layer is greater than or equal to 1.8, and the second refractive index of the at least one conversion pattern is less than 1.

8.

19. The display device according to claim 16, wherein: The backlight unit comprises: Multiple light sources; a light guide plate into which light emitted from the light source enters; and a prism sheet, the prism sheet comprising a prism base located on the light guide plate and a plurality of prisms located on the prism base, The prism substrate includes a first portion having a third refractive index and a second portion having a fourth refractive index which are alternately stacked.

20. The display device according to claim 19, wherein: Each of the plurality of prisms includes a first portion having the third refractive index and a second portion having the fourth refractive index different from the third refractive index, which are alternately stacked.

21. The display device according to claim 16, wherein: The number of the hollow scatterers is greater than the number of the blue light quantum dots.

22. The display device according to claim 16, wherein: A top portion of the at least one conversion pattern has a stripe shape.

23. The display device according to claim 16, wherein: A top portion of the at least one conversion pattern has an island shape.

24. A backlight unit, comprising: Multiple light sources; a light guide plate, into which light emitted from the light source enters; as well as a prism sheet, the prism sheet comprising a prism base located on the light guide plate and a plurality of prisms located on the prism base, The prism substrate includes a first portion having a third refractive index and a second portion having a fourth refractive index which are alternately stacked.

25. The backlight unit according to claim 24, wherein: Each of the prisms includes a first portion having the third refractive index and a second portion having the fourth refractive index different from the third refractive index, which are alternately stacked.

26. The backlight unit according to claim 24, further comprising a prism outer portion, the prism outer portion being located on the light guide plate and disposed on at least some areas of the prism, wherein: The prism outer portion includes alternately stacked first portions having the third refractive index and second portions having the fourth refractive index different from the third refractive index.

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