Color liquid crystal display and display backlight

Abstract

The present invention relates to a display backlight comprising: an excitation source for generating light of a wavelength having a maximum intensity in the range of 445 nm to 465 nm; and a light transmissive medium comprising: K2SiF6: Mn4 + or K2GeF6: Mn4 + for generating light of a wavelength having a maximum intensity in the range of 610 nm to 650 nm; and a green phosphor for generating light of a wavelength having a maximum intensity in the range of 525 nm to 545 nm; wherein the green phosphor has a general composition and a crystal structure MA2S4: Eu, where M is at least one of Mg, Ca, Sr, and Ba, and A is at least one of Ga, A1, In, La, and Y.

Description

Technical Field

[0001] The present invention relates to color liquid crystal displays (LCDs), and in particular, to backlight arrangements for operating high color gamut color LCDs. Background Art

[0002] Color LCDs are used in various electronic devices including televisions, computer monitors, laptop computers, tablet computers, and smart phones. As is well known, most color LCDs include a liquid crystal (LC) display panel and a white light emitting backlight for operating the display panel.

[0003] The present invention is directed to improving the color gamut of LCD backlights and color LCDs, wherein the color gamut refers to the entire range of colors that a display can produce. The present invention is further directed to improving the luminous efficiency of LCD backlights and color LCDs. Summary of the invention

[0004] Embodiments of the present invention are directed to color LCD and display backlights that include red and green photoluminescent materials (such as phosphors, quantum dots, organic dyes, or combinations thereof) that, when excited by excitation light (typically blue light), generate white light for operating the display.

[0005] According to one or more embodiments, a backlight is provided that includes a europium-activated sulfide phosphor. The europium-activated sulfide phosphor may have a general composition based on MA2S4:Eu, where M is at least one of Mg, Ca, Sr, and Ba, and A is at least one of Ga, Al, In, La, and Y. In some embodiments, the europium-activated sulfide phosphor includes strontium, gallium, and sulfur and has a general composition and a crystal structure SrGa2S4:Eu. In some embodiments, the europium-activated sulfide phosphor has a general composition (M)(A)2S4:Eu,M',A', where M is at least one of Mg, Ca, Sr, and Ba; M' is at least one of Li, Na, and K; A is at least one of Ga, Al, and In; and A' is at least one of Si, Ge, La, Y, and Ti. In this chemical formula, the dopants Eu, M', and A' may be present in substitutional or interstitial positions. In some embodiments, the europium activated sulfide phosphor may have a composition (M,M')(A,A')2S4:Eu, wherein M is at least one of Mg, Ca, Sr, and Ba; M' is at least one of Li, Na, and K; A is at least one of Ga, Al, In, La, and Y; and A' is at least one of Si, Ge, and Ti; wherein in the MA2S4 crystal lattice, M' replaces M and A' replaces A. The red photoluminescent material and / or the europium activated sulfide phosphor may include a wavelength conversion layer that is positioned remotely from one or more light emitting devices that include an excitation source (typically a blue LED) for generating excitation light. In other embodiments, one or both of the red photoluminescent material and / or the europium activated sulfide phosphor may be positioned in the one or more light emitting devices. Typically, the wavelength conversion layer constitutes part of the backlight, but it may be considered to constitute part of the display. The wavelength conversion layer, typically comprising a film, has dimensions corresponding to the dimensions of the display. The wavelength conversion layer may be combined with or used to replace the diffusion layer of known displays / backlights.The red photoluminescent material may include phosphor materials, quantum dots, organic dyes, and combinations thereof.

[0006] According to one or more embodiments, a display backlight includes: an excitation source for generating blue excitation light having a dominant emission wavelength in the range of 445 nm to 465 nm; a red photoluminescent material having a peak emission wavelength in the range of 610 nm to 650 nm; a europium activated sulfide phosphor having a peak emission wavelength in the range of 525 nm to 545 nm; and a wavelength conversion layer positioned remote from the excitation source, wherein the wavelength conversion layer includes at least one of the red photoluminescent material and the europium activated sulfide phosphor. In some embodiments, the europium activated sulfide phosphor generates light having a peak emission wavelength in the range of 535 nm to 540 nm. A particular benefit of using a europium activated sulfide phosphor is that this can improve the luminous efficiency of the backlight / display. The europium activated sulfide phosphor advantageously includes strontium (Sr), gallium (Ga) and sulfur (S). In some embodiments, the europium activated sulfide phosphor has a general composition and crystal structure of SrGa2S4:Eu. The sulfide phosphor may further include elements such as alkaline earth metals or halogens and may be coated to improve its reliability.

[0007] In some embodiments, the europium activated sulfide phosphor is positioned in the wavelength conversion layer remote from one or more light emitting devices including the excitation source. Since some europium activated sulfide phosphors (more specifically, SrGa2S4:Eu) may have thermal quenching issues, positioning such phosphor materials in the wavelength conversion layer remote from the light emitting device (LED chip) provides a lower operating temperature environment for the phosphor, which can improve thermal quenching issues. Another benefit of positioning the europium activated sulfide phosphor in a separate wavelength conversion layer and positioning the red photoluminescent material in the one or more light emitting devices (i.e., both red and green are not positioned in the same physical location) is that this can improve the luminous efficiency of the backlight. The increase in luminous efficiency is due in part to the relative size difference between the light emitting device(s) (small area) and the wavelength conversion layer (large area), and this area difference can minimize the absorption of green light by the red photoluminescent material in the light emitting device(s). In addition, by positioning the green europium-activated sulfide phosphor in the wavelength conversion layer downstream of the (several) light-emitting devices, longer wavelength (lower energy) red light that cannot excite the europium-activated sulfide phosphor will be able to pass through the wavelength conversion layer with little or no absorption, thereby improving the luminous efficiency.

[0008] In an embodiment, the red photoluminescent material may include a manganese activated fluoride phosphor. In some embodiments, the manganese activated fluoride phosphor includes a composition of K2SiF6:Mn 4+ (KSF) manganese activated potassium hexafluorosilicate phosphor or composition K2GeF6:Mn 4+(KGF) of manganese-activated potassium hexafluorogermanate phosphor. The manganese-activated fluoride phosphor may include a phosphor of the following composition: K2TiF6:Mn 4+ 、K2SnF6:Mn 4+ 、Na2TiF6:Mn 4+ 、Na2ZrF6:Mn 4+ 、Cs2SiF6:Mn 4+ 、Cs2TiF6:Mn 4+ 、Rb2SiF6:Mn 4+ 、Rb2TiF6:Mn 4+ 、K3ZrF7:Mn 4+ 、K3NbF7:Mn 4+ 、K3TaF7:Mn 4+ 、K3GdF6:Mn 4 + 、K3LaF6:Mn 4+ or K3YF6:Mn 4+ . When a manganese activated fluoride phosphor is used, more particularly (but not exclusively) KSF and / or KGF, it is preferably included in the one or more light emitting devices containing the excitation source. A particular benefit of including the KSF or KGF phosphor in the (several) light emitting devices is a substantial reduction in phosphor usage compared to including the KSF or KGF phosphor in the wavelength conversion layer. KSF and KGF have low blue light (excitation) absorption efficiency requiring the use of high material solids loadings. In large color LCDs such as televisions, computers and tablet computers, the use of such materials in large area wavelength conversion layers can be extremely expensive. In an embodiment of the present invention, the europium activated sulfide phosphor and the red photoluminescent material are positioned in the wavelength conversion layer.

[0009] In various embodiments of the present invention, a backlight including a red photoluminescent material and a green europium activated sulfide phosphor may have an emission spectrum that includes at least 95% of the color gamut of the NTSC (National Television System Committee) and / or at least 100% of the color gamut of the DCI-P3 (Digital Cinema Initiative) RGB color space standard. This color gamut is comparable to that of QD-based (cadmium-free) backlights and exceeds known backlights composed of KSF and β-SiAlON. In this patent specification, a high color gamut backlight and / or color display refers to a backlight / display that is capable of producing at least 95% of the NTSC and / or at least 100% of the DCI-P3 RGB color space standard.

[0010] In various embodiments, the backlight may have an emission spectrum including red, green and blue light emission peaks, wherein the red light peak has chromaticity coordinates CIE x=0.6700 to 0.6950, CIE y=0.3300 to 0.2950; the green light peak has chromaticity coordinates CIE x=0.1950 to 0.2950, ​​CIE y=0.7250 to 0.6250; and the blue light peak has chromaticity coordinates CIE x=0.1600 to 0.1400, CIE y=0.0180 to 0.0600.

[0011] In various embodiments including a wavelength conversion layer, the wavelength conversion layer comprises a separate film manufactured separately from other components of the backlight. In other embodiments, the photoluminescent wavelength conversion layer can be manufactured as part of another component of the backlight or display, for example, it can be deposited directly onto, i.e., in direct contact with, a component of the backlight or display.

[0012] In various embodiments, the backlight of the present invention may include an edge-lit or direct-lit arrangement.

[0013] In an edge-lit arrangement, the backlight further comprises a light guide, and the light emitting device is configured to couple light into at least one edge of the light guide and the wavelength conversion layer is disposed adjacent to the light guide. In some embodiments, the wavelength conversion layer is in direct contact with the light guide. To increase emission brightness, the backlight may further comprise a brightness enhancement film (BEF) and the wavelength conversion layer is disposed between the light guide and the brightness enhancement film. The wavelength conversion layer may be in direct contact with the BEF.

[0014] In some edge-lit arrangements, the backlight may further include a light reflective surface and the wavelength conversion layer is disposed between the light reflective surface and the light guide.The wavelength conversion layer may be in direct contact with the light guide or in direct contact with the light reflective surface.

[0015] In a direct-lit arrangement, the backlight may further include a brightness enhancement film (BEF) and the wavelength conversion layer is disposed adjacent to the brightness enhancement film. The wavelength conversion layer may be in direct contact with the BEF.

[0016] In various embodiments of the present invention, the wavelength conversion layer may further include particles of light scattering material. The inclusion of particles of light scattering material may increase the uniformity of light emission from the wavelength conversion layer and may eliminate the need for a separate light diffusion layer as is commonly used in known displays. Additionally, combining particles of light scattering material with the red or green photoluminescent material of the wavelength conversion layer may result in increased light generation of the photoluminescent wavelength conversion layer and a substantial reduction in the amount of photoluminescent material required to generate a given color of light by up to 40%. In view of the relatively high cost of photoluminescent materials, the inclusion of light scattering material may result in a significant reduction in the manufacturing cost of larger displays such as tablet computers, laptop computers, TVs, and monitors. Additionally, the light emitting device may further include particles of light scattering material.

[0017] The light scattering material may include, for example, particles of zinc oxide (ZnO), silicon dioxide (SiO2), titanium dioxide (TiO2), magnesium oxide (MgO), barium sulfate (BaSO4), aluminum oxide (Al2O3), or a combination thereof. The light scattering material particles may have an average diameter such that they scatter more excitation light than the red or green light generated by photoluminescence. In some embodiments, the light diffusing material particles have an average diameter (D50) of 200 nm or less, typically 100 nm to 150 nm.

[0018] According to one or more embodiments, a backlight is provided in which the red and green photoluminescent materials are positioned at different physical locations along the light path of the backlight / display. For example, one of the red and green photoluminescent materials may be positioned within the one or more light emitting devices including the excitation source and the other photoluminescent material is positioned in a photoluminescent wavelength conversion layer located remotely from the one or more light emitting devices. In a preferred embodiment, the red photoluminescent material is positioned within the one or more light emitting devices and the green photoluminescent material is positioned within the photoluminescent wavelength conversion layer. In other embodiments, the red and green photoluminescent materials may be positioned in respective wavelength conversion layers or within respective light emitting devices. The red and green photoluminescent materials may include phosphor materials, quantum dots, organic dyes, and combinations thereof.

[0019] According to one or more embodiments, a display backlight includes: one or more light emitting devices including an excitation source for generating blue excitation light having a dominant emission wavelength in the range of 445 nm to 465 nm and a red photoluminescent material having a peak emission wavelength in the range of 610 nm to 650 nm; and a wavelength conversion layer positioned remotely from the light emitting devices; the wavelength conversion layer including a green photoluminescent material having a peak emission wavelength in the range of 525 nm to 545 nm. A particular benefit of positioning the red photoluminescent material in the one or more light emitting devices and positioning the green photoluminescent material in a separate wavelength conversion layer (i.e., both red and green are not positioned in the same physical location) is that this can increase the luminous efficiency of the backlight. As discussed above, the luminous efficiency increase is due in part to the size difference between the light emitting device(s) (small area) and the wavelength conversion layer (large area) and this area difference can minimize the absorption of green light by the red photoluminescent material in the light emitting device(s). Additionally, positioning a green europium activated sulfide phosphor in the wavelength conversion layer downstream of the light emitting device(s) enables longer wavelength red light to pass through the wavelength conversion layer with little or no absorption, thereby improving light emission efficiency. In such an arrangement, the green photoluminescent material may include a β-SiAlON phosphor and the red photoluminescent material may include, for example, a phosphor having the composition MSe 1-x S x :Eu based IIA / IIB group selenide sulfide phosphor, wherein M is at least one of Mg, Ca, Sr, Ba and Zn and 0 <x<1.0。

[0020] The green photoluminescent material advantageously comprises a europium activated sulfide phosphor. The europium activated sulfide phosphor may have a general composition based on MA2S4:Eu, wherein M is at least one of Mg, Ca, Sr, and Ba, and A is at least one of Ga, Al, In, La, and Y. In some embodiments, the europium activated sulfide phosphor comprises strontium, gallium, and sulfur and may have a general composition and a crystal structure SrGa2S4:Eu. In some embodiments, the europium activated sulfide phosphor has a general composition (M)(A)2S4:Eu,M',A', wherein M is at least one of Mg, Ca, Sr, and Ba; M' is at least one of Li, Na, and K; A is at least one of Ga, Al, and In; and A' is at least one of Si, Ge, La, Y, and Ti. In this chemical formula, the dopants Eu, M', and A' may be present in substitutional or interstitial positions. In some embodiments, the europium activated sulfide phosphor may have a composition (M,M')(A,A')2S4:Eu, wherein M is at least one of Mg, Ca, Sr, and Ba; M' is at least one of Li, Na, and K; A is at least one of Ga, Al, In, La, and Y; and A' is at least one of Si, Ge, and Ti; wherein in the MA2S4 crystal lattice, M' replaces M and A' replaces A. The sulfide phosphor may further include elements such as alkaline earth metals or halogens. A particular benefit of using europium activated sulfide phosphors is that this can improve luminous efficiency. Since SrGa2S4:Eu may have thermal quenching issues, locating this phosphor material in the wavelength conversion layer at a remote location of the light emitting device (LED chip) provides a lower operating temperature environment for the phosphor, which can improve thermal quenching issues.

[0021] Additionally or alternatively, the green photoluminescent material may include quantum dot material.

[0022] In an embodiment, the red photoluminescent material may include a manganese activated fluoride phosphor. In some embodiments, the manganese activated fluoride phosphor includes a composition of K2SiF6:Mn 4+ (KSF) manganese activated potassium hexafluorosilicate phosphor or composition K2GeF6:Mn 4+A manganese-activated potassium hexafluorogermanate phosphor (KGF) is used in the wavelength conversion layer. A particular benefit of using the KSF or KGF phosphor in the light emitting device(s) is that the use of red phosphor is substantially reduced compared to including the KSF or KGF phosphor in the wavelength conversion layer. KSF and KGF have low blue light (excitation) absorption efficiency requiring the use of high material solids loading. In large color LCDs such as televisions, computers and tablet computers, it would be extremely expensive to use such materials in the large area wavelength conversion layer. A further advantage of using the SrGa2S4:Eu phosphor in the wavelength conversion layer is that it is avoided from chemically reacting with the KSF or KGF phosphor. In other embodiments, the manganese-activated fluoride phosphor may include a phosphor selected from a composition of the group consisting of: K2TiF6:Mn 4+ 、K2SnF6:Mn 4+ 、Na2TiF6:Mn 4+ 、Na2ZrF6:Mn 4+ 、Cs2SiF6:Mn 4+ 、Cs2TiF6:Mn 4+ 、Rb2SiF6:Mn 4+ 、Rb2TiF6:Mn 4+ 、K3ZrF7:Mn 4+ 、K3NbF7:Mn 4+ 、K3TaF7:Mn 4+ 、K3GdF6:Mn 4+ 、K3LaF6:Mn 4+ or K3YF6:Mn 4+ .

[0023] In various embodiments of the present invention, a backlight including a manganese activated fluoride red phosphor and a green sulfide phosphor may have an emission spectrum that includes at least 95% of the color gamut of the NTSC (National Television System Committee) and / or at least 100% of the color gamut of the DCI-P3 (Digital Cinema Initiative) RGB color space standard. This color gamut is comparable to that of QD-based (cadmium-free) backlights and exceeds the color gamut of known backlights composed of KSF and β-SiAlON. In this patent specification, a high color gamut backlight and / or color display refers to a backlight / display that is capable of producing at least 95% of the NTSC and / or at least 100% of the DCI-P3 RGB color space standard.

[0024] In various embodiments, the backlight may have an emission spectrum including red, green, and blue emission peaks.

[0025] The red light peak has chromaticity coordinates CIE x=0.6700 to 0.6950, CIE y=0.3300 to 0.2950; the green light peak has chromaticity coordinates CIE x=0.1950 to 0.2950, ​​CIE y=0.7250 to 0.6250; and the blue light peak has chromaticity coordinates CIE x=0.1600 to 0.1400, CIE y=0.0180 to 0.0600.

[0026] In various embodiments, the wavelength conversion layer comprises a separate film manufactured separately from other components of the backlight. In other embodiments, the photoluminescent wavelength conversion layer may be manufactured as part of another component of the backlight or display, for example, it may be deposited directly onto, i.e., in direct contact with, a component of the backlight or display.

[0027] In various embodiments, the backlight of the present invention may include an edge-lit or direct-lit arrangement.

[0028] In an edge-lit arrangement, the backlight further comprises a light guide, and the light emitting device is configured to couple light into at least one edge of the light guide and the wavelength conversion layer is disposed adjacent to the light guide. In some embodiments, the wavelength conversion layer is in direct contact with the light guide. To increase emission brightness, the backlight may further comprise a brightness enhancement film (BEF) and the wavelength conversion layer is disposed between the light guide and the brightness enhancement film. The wavelength conversion layer may be in direct contact with the BEF.

[0029] In some edge-lit arrangements, the backlight may further include a light reflective surface and the wavelength conversion layer is disposed between the light reflective surface and the light guide.The wavelength conversion layer may be in direct contact with the light guide or in direct contact with the light reflective surface.

[0030] In a direct-lit arrangement, the backlight may further include a brightness enhancement film (BEF) and the wavelength conversion layer is disposed adjacent to the brightness enhancement film. The wavelength conversion layer may be in direct contact with the BEF.

[0031] In various embodiments of the present invention, the wavelength conversion layer may further include particles of light scattering material. The inclusion of particles of light scattering material may increase the uniformity of light emission from the wavelength conversion layer and may eliminate the need for a separate light diffusing layer as is commonly used in known displays. Additionally, combining particles of light scattering material with the red or green photoluminescent material of the wavelength conversion layer may result in increased light generation of the photoluminescent wavelength conversion layer and a substantial reduction in the amount of photoluminescent material required to generate a given color of light by up to 40%. In view of the relatively high cost of photoluminescent materials, the inclusion of light scattering material may result in a significant reduction in the manufacturing cost of larger displays such as tablet computers, laptop computers, TVs, and monitors. Additionally, the light emitting device may further include particles of light scattering material.

[0032] The light scattering material may include, for example, particles of zinc oxide (ZnO), silicon dioxide (SiO2), titanium dioxide (TiO2), magnesium oxide (MgO), barium sulfate (BaSO4), aluminum oxide (Al2O3), or a combination thereof. The light scattering material particles may have an average diameter such that they scatter more excitation light than the red or green light generated by photoluminescence. In some embodiments, the light diffusing material particles have an average diameter (D50) of 200 nm or less, typically 100 nm to 150 nm.

[0033] According to one or more embodiments, a display backlight is considered, comprising: a light emitting device, comprising an excitation source for generating blue excitation light having a main emission wavelength in the range of 445 nm to 465 nm and a composition of K2SiF6:Mn 4+ a manganese-activated potassium hexafluorosilicate phosphor; and a wavelength conversion layer positioned at a remote location of the light-emitting device and comprising a green photoluminescent material having a peak emission wavelength in the range of 525 nm to 545 nm, the green photoluminescent material comprising strontium, gallium and sulfur, having a general composition and a crystal structure of SrGa2S4:Eu.

[0034] The green photoluminescent material in the wavelength conversion layer may include a europium-activated sulfide phosphor including strontium, gallium, and sulfur.

[0035] The europium-activated sulfide phosphor may have a general composition and crystal structure of SrGa2S4:Eu.

[0036] According to one or more embodiments, a display backlight is considered, comprising: a light emitting device comprising an excitation source for generating blue excitation light having a main emission wavelength in the range of 445nm to 465nm and a red photoluminescent material having a peak emission wavelength in the range of 610nm to 650nm; and a wavelength conversion layer positioned at a remote location of the light emitting device; the wavelength conversion layer comprising a green photoluminescent material having a peak emission wavelength in the range of 525nm to 545nm, the green photoluminescent material comprising a quantum dot material. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] For a better understanding of the present invention, embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a schematic cross-sectional illustration of a color LCD according to an embodiment of the present invention;

[0038] Figure 2 yes Figure 1 A schematic cross-sectional illustration of a front panel of a color LCD;

[0039] Figure 3 yes Figure 1 Schematic diagram of a unit pixel of a color filter panel of a color LCD;

[0040] Figure 4 The filter characteristics and transmittance versus wavelength of the red, green and blue filter elements of the color filter plate of the color LCD display according to the embodiment of the present invention are shown;

[0041] Figure 5 yes Figure 1 A schematic cross-sectional illustration of a backplane of a color LCD;

[0042] Figure 6 is a cross-sectional side view of a light emitting device according to an embodiment of the present invention;

[0043] Figure 7 yes Figure 1 Schematic cross-sectional illustration of an edge-lit backlight for a color LCD of , wherein the photoluminescent layer is positioned between the light guide and the BEF (brightness enhancement film);

[0044] Figure 8 is a schematic cross-sectional illustration of an edge-lit backlight according to an embodiment of the present invention, wherein a photoluminescent layer is positioned between a light guide and a light reflective layer;

[0045] Fig. 9 is a schematic exploded cross-sectional illustration of a direct-illumination backlight according to an embodiment of the present invention;

[0046] Fig.10The emission spectrum, intensity (au) versus wavelength (nm) of a light emitting device according to an embodiment of the present invention is shown;

[0047] Fig.11 The emission spectrum, intensity (au) versus wavelength (nm) of the photoluminescence wavelength conversion layer according to an embodiment of the present invention is shown;

[0048] Fig.12 shows the emission spectra, intensity (au) versus wavelength (nm), of a backlight according to an embodiment of the present invention before and after BEF;

[0049] Fig.13 Showing NTSC standard 1931 CIE color coordinates and RGB color coordinates of a backlight according to some embodiments;

[0050] Fig.14 Showing the emission spectra, Intensity (au) versus Wavelength (nm) of backlight BL.2 (tuned to DCI-P3 white point) before and after AUO color filter; and

[0051] Fig.15 Shown is the emission spectrum, Intensity (au) versus Wavelength (nm) of backlight BL.3 (tuned to DCI-P3 white point) before and after AUO color filter. DETAILED DESCRIPTION

[0052] Embodiments of the present invention are directed to color LCD backlights that include red- and green-emitting photoluminescent materials (e.g., phosphors, quantum dots, and / or organic dyes) that, when excited by excitation light (typically blue light), generate a combined white light output for operating the display.

[0053] According to some embodiments of the present invention, a backlight includes a europium activated sulfide phosphor, such as, for example, a europium activated sulfide phosphor based on the general composition of MA2S4:Eu, where M is at least one of Mg, Ca, Sr, and Ba, and A is at least one of Ga, Al, In, La, and Y. In some embodiments, the europium activated sulfide phosphor has a general composition and crystal structure of SrGa2S4:Eu. The sulfide phosphor may further include elements such as halogens and may be coated to improve its reliability. The red photoluminescent material and / or the europium activated sulfide phosphor may include a wavelength conversion layer that is positioned remotely from one or more light emitting devices that include an excitation source (typically a blue LED) for generating excitation light. In other embodiments, one or both of the red photoluminescent material and / or the europium activated sulfide phosphor may be positioned in the one or more light emitting devices. Typically, the wavelength conversion layer forms part of the backlight, but it may be considered to form part of the display. Typically, the wavelength conversion layer, which comprises a film, has dimensions corresponding to the dimensions of the display. The wavelength conversion layer may be combined with or used to replace the diffusion layer of a known display / backlight. The red photoluminescent material may include phosphor materials, quantum dots, organic dyes and combinations thereof.

[0054] According to other embodiments of the present invention, a backlight includes positioning red and green photoluminescent materials at different physical locations along the light path of the backlight / display. For example, the red and green photoluminescent materials may be positioned within separate components of the backlight, i.e., at separate physical locations, where one photoluminescent material is positioned in a light-emitting package containing an excitation source (typically a blue LED) and the other photoluminescent material is positioned in a photoluminescent wavelength conversion layer located remotely from the light-emitting package. "Remotely" in this specification means that the two components are spatially separated to (for example) reduce heat transfer between the components. The components may be separated by air or a light-transmitting medium. In a preferred embodiment, the red photoluminescent material is positioned within the one or more light-emitting devices and the green photoluminescent material is positioned within the photoluminescent wavelength conversion layer. In other embodiments, the red and green photoluminescent materials may be positioned in the respective wavelength conversion layers or within the respective light-emitting devices. A particular benefit of locating the red photoluminescent material in the one or more light emitting devices and the green photoluminescent material in a separate wavelength converting layer is that this can increase the light emitting efficiency of the backlight.

[0055] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which are provided as illustrative examples of the present invention to enable those skilled in the art to practice the present invention. It should be noted that the following figures and examples are not intended to limit the scope of the present invention to a single embodiment, but other embodiments can be made by exchanging some or all of the described or illustrated elements. In addition, although some elements of the present invention can be partially or completely implemented using known components, only the parts of such known components required for understanding the present invention will be described and the detailed description of other parts of such known components will be omitted to avoid making the present invention unclear. In this specification, the embodiment showing a single array member should not be considered as restrictive; specifically, unless otherwise expressly provided herein, the present invention is intended to cover other embodiments comprising a plurality of identical components, and vice versa. In addition, unless expressly stated in itself, the applicant is not intended to consider any term in this specification or claims to have an abnormal or special meaning. In addition, the present invention covers the current and future known equivalents of the known components mentioned in this specification by way of illustration. Throughout this specification, the same reference numerals are used to indicate similar features.

[0056] refer to Figure 1 , which shows a schematic cross-sectional view of a light-transmitting color LCD (liquid crystal display) 100 formed according to an embodiment of the present invention. The color LCD 100 includes an LC (liquid crystal) display panel 102 and a display backlight 104. The backlight 104 ( Figures 7 to 9 ) is operable to generate white light 140 for operating the LC display panel 102.

[0057] LC display panel

[0058] like Figure 1 As shown in , the LC display panel 102 includes a transparent (light-transmitting) front (light-emitting / image-emitting) plate 106 , a transparent backplate 108 , and liquid crystal (LC) 110 filling the volume between the frontplate 106 and the backplate 108 .

[0059] like Figure 2 , the front plate 106 may include a glass plate 112 having a first polarizing filter layer 116 on its upper surface (i.e., the surface of the plate including the viewing surface 114 of the display). Optionally, the outermost viewing surface of the front plate may further include an anti-reflective layer 118. The glass plate 112 may further include a color filter plate 120 and a light-transmitting common electrode plane 122 (e.g., transparent indium tin oxide ITO) on its underside (i.e., the surface of the front plate 106 facing the liquid crystal (LC) 110).

[0060] The color filter panel 120 includes an array of sub-pixel filter elements 124, 126, 128 that transmit red (R), green (G), and blue (B) light. Each unit pixel 130 of the display includes a group of three sub-pixel filter elements 124, 126, 128. Figure 3 1 is a schematic diagram of a unit pixel 130 of a color filter plate 120. As shown, each RGB sub-pixel 124, 126, 128 includes a corresponding color filter pigment (usually an organic dye) that allows only light corresponding to the color of the sub-pixel to pass through. The RGB sub-pixel elements 124, 126, 128 may be deposited on a glass plate 112 with an opaque partition / wall (black matrix) 132 between each of the sub-pixels 124, 126, 128. The black matrix 132 may be formed as a metal (such as, for example, chromium) grid mask to define the sub-pixels 124, 126, 128 and provide an opaque gap between the sub-pixels and the unit pixel 130. To minimize reflections from the black matrix, a double layer of Cr and CrOx may be used, but the layers may of course include materials other than Cr and CrOx. Methods including photolithography may be used to pattern a black matrix film that may be sputter-deposited below or above the photoluminescent material. Figure 4 Demonstrating the filtering characteristics and transmittance versus wavelength of the red (R), green (G) and blue (B) filter elements of Hisense filter panels optimized for TV applications.

[0061] refer to Figure 5 , the backplane 108 may include a glass plate 134 having a TFT (thin film transistor) layer 136 on its upper surface (the surface facing the LC). The TFT layer 136 includes a TFT array in which there is a transistor corresponding to each individual color sub-pixel 124, 126, 128 of each unit pixel 130. Each TFT is operable to selectively control the passage of light through its corresponding sub-pixel. A second polarization filter layer 138 is provided on the lower surface of the glass plate 134. The polarization directions of the two polarization filters 116 and 138 are aligned perpendicularly to each other.

[0062] Backlight

[0063] The backlight 104 is operable to generate and emit light from a front light emitting surface 142 (an upper surface facing the rear of the display panel, Figure 7 ) white light 140 to operate the LC display panel 102.

[0064] Backlight: Light-emitting device

[0065] Figure 61 is a schematic cross-sectional illustration of a light emitting device 146 according to some embodiments. The light emitting device 146 is operable to generate composite light comprising a combination of: blue excitation light; and one of red photoluminescent light (peak emission wavelength 610nm to 650nm) or green photoluminescent light (peak emission wavelength 530nm to 545nm).

[0066] like Figure 6 , the device 146 may include a blue-emitting GaN LED chip 42 (dominant emission wavelength 445nm to 465nm) (preferably 445nm to 455nm) housed within a package. A recess 48 of a low temperature co-fired ceramic (LTCC) may be included, for example, which is configured to receive one or more LED chips 42. The package further includes electrical connectors 50 and 52, which also define corresponding electrode contact pads 54 and 56 on the bottom of the recess 48. The LED chip 42 may be mounted to a thermally conductive pad 58 positioned on the bottom of the recess 48 using, for example, an adhesive or solder. Bonding wires 60 and 62 are used to electrically connect the electrode pads of the LED chip to the corresponding electrode contact pads 54 and 56 on the bottom of the package and a light-transmitting (transparent) polymer material 64 (typically silicone) loaded with a photoluminescent material (e.g., phosphor) is used to completely fill the recess 48 so that the exposed surface of the LED chip 42 is covered by the phosphor / polymer material mixture. To enhance the emission brightness of the device, the walls of the groove 48 may be inclined and have a light reflective surface. According to the present invention, the photoluminescent material comprises a green or red emitting photoluminescent material. In a preferred embodiment, the red or green photoluminescent material comprises a narrow band phosphor. In operation, the light emitting device 146 generates a composite light 148 comprising a combination of: blue excitation light from the LED chip 42; and photoluminescent light generated by the photoluminescent material in response to excitation by the blue excitation light. Depending on the photoluminescent material present in the light emitting device, the photoluminescent light may be green or red.

[0067] like Figure 7 , the backlight 104 may include an edge-lit arrangement containing a light guide (waveguide) 144, with one or more light emitting devices 146 positioned along one or more edges of the light guide 144. As indicated, the light guide 144 may be flat; however, in some embodiments, it may be tapered (wedge-shaped) to facilitate light emission from a front emitting surface (e.g., Figure 7 The light emitting device 146 is configured so that, in operation, it generates a composite light 148 that is coupled into one or more edges of the light guide 144 and then guided by total internal reflection throughout the volume of the light guide 144 and ultimately emitted from the front surface of the light guide 144 (the upper surface facing the display panel 102). Figure 7As shown in FIG. 1 and to prevent light from escaping the backlight 104, the rear surface of the light guide 144 (the lower surface as shown) may include a light reflective layer (surface) 150, such as VikuitiTM ESR (Enhanced Spectral Reflector) film from 3M.

[0068] A photoluminescence wavelength conversion layer 152 and a brightness enhancement film (BEF) 154 are provided on the front light emitting surface (the upper surface as shown) of the light guide 144. Figure 7 In the illustrated embodiment, the photoluminescence wavelength conversion layer 152 is disposed between the light guide 144 and the BEF 154 .

[0069] Backlight: Brightness Enhancement Film (BEF)

[0070] The brightness enhancement film (BEF), also known as a prism sheet, includes a precision microstructured optical film and controls the emission of light 140 from the backlight within a fixed angle (typically 70 degrees), thereby increasing the luminous efficiency of the backlight. Typically, the BEF includes an array of microprisms on the light-emitting surface of the film and can increase the brightness by 40% to 60%. The BEF 154 may include a single BEF or a combination of multiple BEFs, and an even greater brightness increase may be achieved in the latter case. Examples of suitable BEFs include VikuitiTM BEFII from 3M or a prism sheet from MNTech. In some embodiments, the BEF 154 may include a multifunctional prism sheet (MFPS) that integrates a prism sheet with a diffuser film and may have a higher luminous efficiency than an ordinary prism sheet. In some embodiments, the BEF 154 may include a microlens film prism sheet (MLFPS), such as a microlens film prism sheet purchased from MNTech.

[0071] Backlight: Photoluminescent wavelength conversion layer

[0072] For the sake of brevity, in the following description, the photoluminescent wavelength conversion layer will be referred to as a “photoluminescent layer”.

[0073] The photoluminescent layer 152 contains a red or green emitting photoluminescent material and in operation converts at least a portion of the blue excitation light of the composite light 148 generated by the device 146 to produce a white light emission product 140 for operating the LC display panel 104. More specifically, the photoluminescent layer 152 contains a red emitting (peak emission wavelength λ ) photoluminescent material that is excitable by blue light. pe = 600nm to 650nm) photoluminescent material or green light emitting (peak emission wavelength λ pe =530nm to 545nm) photoluminescent materials. The combination of photoluminescent generated light 158 ​​and composite light 148 results in white light emission product 140. To optimize the efficiency and color gamut of the display, the red and green emitting photoluminescent materials are selected so that their peak emission (PE) wavelengths λ pePreferably, the green light emitting photoluminescent material has a peak emission wavelength λ pe ≈535nm. To maximize display color gamut and efficiency, the red-emitting and / or green-emitting photoluminescent materials present in light emitting device 146 and photoluminescent layer 152 preferably include narrow-band photoluminescent materials having an emission peak including a FWHM (full width at half maximum) of about 50nm or less.

[0074] The red and green emitting photoluminescent materials may include phosphor materials, quantum dots (QDs), organic dyes, or combinations thereof. For purposes of illustration only, the present description refers specifically to photoluminescent materials embodied as phosphor materials. Phosphor materials may include inorganic and organic phosphor materials. Inorganic phosphors may include aluminate, silicate, phosphate, borate, sulfate, chloride, fluoride, or nitride phosphor materials. As is well known, phosphor materials are doped with rare earth elements known as activators. Activators typically include divalent europium, cerium, or tetravalent manganese. Dopants such as halogens may be incorporated into the crystal lattice either substitutionally or interstitially and may, for example, reside on lattice sites of a host material and / or reside interstitially within the host material.

[0075] Red-emitting phosphor materials

[0076] In this patent specification, a red-emitting phosphor refers to a phosphor material that generates light having a peak emission wavelength in the range of 610 nm to 650 nm (i.e., in the orange to red region of the visible spectrum). Preferably, the red-emitting phosphor is a narrow-band phosphor material and has a half-width emission intensity of less than about 50 nm. Examples of red-emitting phosphor materials suitable for use in the light-emitting device 146 and the photoluminescent layer 152 are given in Table 1.

[0077]

[0078] Narrow-band red phosphors: manganese-activated fluoride phosphors

[0079] An example of a manganese activated fluoride phosphor is manganese activated potassium hexafluorosilicate phosphor (KSF) - K2SiF6:Mn 4+ An example of such a phosphor is NR6931 KSF phosphor from Intermatrix, Inc. of Fremont, California, USA, which has a peak emission wavelength of about 632 nm. The KSF phosphor can be excited by blue excitation light and generates a phosphor having a peak emission wavelength (λ) between about 631 nm and about 632 nm. pe ) and a FWHM of about 5 nm to about 10 nm (depending on how it is measured, i.e., whether the width considers a single peak or two peaks). Other manganese-activated phosphors may include K2GeF6:Mn 4+ 、K2TiF6:Mn4+ , K2SnF6:Mn 4+ , Na2TiF6:Mn 4+ , Na2ZrF6:Mn 4+ , Cs2SiF6:Mn 4+ , Cs2TiF6:Mn 4+ , Rb2SiF6:Mn 4+ , Rb2TiF6:Mn 4+ , K3ZrF7:Mn 4+ , K3NbF7:Mn 4+ , K3TaF7:Mn 4+ , K3GdF6:Mn 4+ , K3LaF6:Mn 4+ or K3YF6:Mn 4+ .

[0080] Narrow-band red phosphors: Group IIA / IIB selenium sulfide-based phosphors

[0081] Examples of phosphor materials based on group IIA / IIB selenide sulfides have the composition MSe1-xSx:Eu, where M is at least one of Mg, Ca, Sr, Ba, and Zn and 0 < x < 1.0. A specific example of such a phosphor material is the CSS phosphor (CaSe 1-x S x :Eu). Details of the CSS phosphor are provided in co-pending U.S. patent application Ser. No. 15 / 282,551, filed Sep. 30, 2016, the entire content of which is incorporated herein by reference. The CSS narrowband red phosphor described in U.S. patent application Ser. No. 15 / 282,551 can be used in the present invention. The peak emission wavelength of the CSS phosphor can be tuned from 600 nm to 650 nm by varying the S / Se ratio in the composition and exhibits a narrowband red emission spectrum with a FWHM in the range of about 48 nm to about 60 nm (longer wavelengths generally have larger FWHM values).

[0082] Green light emitting phosphor materials

[0083] In this patent specification, a green-emitting phosphor refers to a phosphor material that generates light having a peak emission wavelength in the range of 525 nm to 545 nm (i.e., in the green region of the visible spectrum). In some embodiments, the green-emitting phosphor generates light having a peak emission wavelength in the range of 535 nm to 540 nm. Preferably, the green-emitting phosphor is a narrowband phosphor material and has a full width at half maximum emission intensity of less than about 50 nm. Examples of green-emitting phosphor materials suitable for use in the light-emitting device 146 and the photoluminescent layer 152 are given in Table 2.

[0084]

[0085]

[0086]

[0087] Green emitting phosphor material: Green sulfide phosphor

[0088] An example of a green sulfide phosphor material has a general composition based on MA2S4:Eu, where M is at least one of Mg, Ca, Sr, and Ba, and A is at least one of Ga, Al, In, La, and Y. To improve reliability, the phosphor particles may be coated with one or more oxides selected from the group of materials consisting of aluminum oxide, silicon oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and chromium oxide. An example of such a phosphor is the NBG phosphor from Intermatrix, Inc. of Fremont, California, USA, which has a peak emission wavelength between about 535 nm and about 540 nm. Details of green fluoride phosphors are provided in co-pending PCT patent publication No. WO2018 / 080936, published on May 3, 2018, the entire text of which is incorporated herein by reference. The green fluoride phosphors described in PCT patent publication WO2018 / 080936 can be used in the present invention. For example, a narrow-band green phosphor may have a composition (M)(A)2S4:Eu, M', A', wherein M is at least one of Mg, Ca, Sr, and Ba; M' is at least one of Li, Na, and K; A is at least one of Ga, Al, and In; and A' is at least one of Si, Ge, La, Y, and Ti. In the latter formula, the dopants Eu, M', and A' may be present in substitutional positions, although other incorporation options, such as interstitial positions, are also contemplated. Furthermore, a green sulfide phosphor may have a composition (M, M')(A, A')2S4:Eu, wherein M is at least one of Mg, Ca, Sr, and Ba; M' is at least one of Li, Na, and K; A is at least one of Ga, Al, In, La, and Y; and A' is at least one of Si, Ge, and Ti; wherein in the MA2S4 crystal lattice, M' replaces M and A' replaces A. Specific substitution positions are identified in the latter formula, but alternative substitution positions are contemplated; for example, it is contemplated that for doping Li and Si, the following structure could provide alternative substitution positions for Li: Sr(Ga 1-2x Si x Li 2x )2S4:Eu, wherein M is at least one of Mg, Ca, Sr and Ba; and A is at least one of Ga, Al, In, La and Y; wherein 0 <x<0.1。

[0089] Quantum Dot (QD) Materials

[0090] Quantum dots (QDs) are portions of matter (e.g., semiconductors) whose excitons are confined in all three spatial dimensions that can be excited by radiant energy to emit light of a specific wavelength or range of wavelengths. QDs may include different materials, such as cadmium selenide (CdSe). The color of the light generated by the QDs is achieved through quantum confinement effects associated with the nanocrystalline structure of the QDs. The energy level of each QD is directly related to the physical size of the QD. For example, larger QDs (e.g., red QDs) can absorb and emit photons with relatively lower energy (i.e., relatively longer wavelengths). On the other hand, green QDs (which have smaller sizes) can absorb and emit photons with relatively higher energy (shorter wavelengths). Examples of suitable QDs may include CdZnSeS (cadmium zinc selenide), Cd x Zn 1-x Se (cadmium zinc selenide), CdSe x S 1-x (cadmium sulfide selenide), CdTe (cadmium telluride), CdTe x S 1-x (cadmium telluride sulfide), InP (indium phosphide), In x Ga 1-x P (Indium Gallium Phosphide), InAs (Indium Arsenide), CuInS2 (Copper Indium Sulfide), CuInSe2 (Copper Indium Selenide), CuInS x Se 2-x (Copper Indium Sulfide Selenide), CuIn x Ga 1-x S2 (Copper Indium Gallium Sulfide), CuIn x Ga 1-x Se2 (copper indium gallium selenide), CuIn x Al 1-x Se2 (copper indium aluminum selenide), CuGaS2 (copper gallium sulfide) and CuInS 2x ZnS 1-x(Copper Indium Zinc Sulfide). QD materials may include core / shell nanocrystals containing different materials in an onion-like structure. For example, the above exemplary materials may be used as the core material of the core / shell nanocrystals. The optical properties of the core nanocrystals in one material may be altered by growing an epitaxial shell of another material. Depending on the requirements, the core / shell nanocrystals may have a single shell or multiple shells. The shell material may be selected based on energy gap engineering. For example, the shell material may have an energy gap greater than the core material so that the shell of the nanocrystal may separate the surface of the optically active core from its surrounding medium. For cadmium-based QDs (e.g., CdSeQDs), the following chemical formulas may be used to synthesize core / shell quantum dots: CdSe / ZnS, CdSe / CdS, CdSe / ZnSe, CdSe / CdS / ZnS, or CdSe / ZnSe / ZnS. Similarly, for CuInS2 quantum dots, the following chemical formulas can be used to synthesize core / shell nanocrystals: CuInS2 / ZnS, CuInS2 / CdS, CuInS2 / CuGaS2, CuInS2 / CuGaS2 / ZnS, and so on.

[0091] Examples of suitable quantum dot compositions are given in Table 3

[0092]

[0093]

[0094] There are various ways to implement a backlight according to the present invention. For example, as described above, in some embodiments, a red-emitting photoluminescent material may be positioned in the light emitting device 146 and a green-emitting photoluminescent material may be positioned in the photoluminescent layer 152. In other embodiments, a green-emitting photoluminescent material may be positioned in the light emitting device 146 and a red-emitting photoluminescent material may be positioned in the photoluminescent layer 152. It is contemplated that in other embodiments both red-emitting and green-emitting photoluminescent materials may be positioned in the photoluminescent layer 152. It will be appreciated that in such an arrangement, the light emitting device 146 need not include red-emitting and green-emitting photoluminescent materials and the light emitting device 146 may generate only blue excitation light. In some arrangements, the red-emitting and green-emitting photoluminescent materials may be incorporated into the photoluminescent layer 152 as a mixture. In other arrangements, the red-emitting and green-emitting photoluminescent materials may be incorporated into separate respective photoluminescent layers. In the context of this specification, “photoluminescent layer” encompasses both single layers and multiple layers, ie, “photoluminescent layer” comprises “several photoluminescent layers.” Regardless of the location of the red and green photoluminescent materials, the photoluminescent layer may be implemented in many ways.

[0095] In some embodiments, the photoluminescent layer 152 is disposed adjacent to the BEF 154. When an inorganic phosphor material is used, a red- or green-emitting phosphor in particle form may be incorporated as a mixture into a curable light-transmitting liquid binder material and the mixture may be deposited as a uniform layer on a light-transmitting substrate using, for example, screen printing or slot die coating. In some embodiments, the BEF 154 may include a light-transmitting substrate and the photoluminescent layer 152 may be deposited directly onto the BEF 154. In this patent specification, "direct deposition" means "in direct contact with...", i.e., there are no intervening layers or air gaps between the layers. When screen printing is used to deposit the photoluminescent layer, the light-transmitting binder material may include, for example, a light-transmitting UV-curable acrylic adhesive, such as UVA4103 transparent substrate from Lianda Technology, Waterloo, Indiana, USA. The advantage of depositing the photoluminescent layer directly onto the BEF is that this may increase light emission from the backlight by eliminating the air interface between the photoluminescent layer and the BEF. Otherwise, this air interface may cause light to be more likely to be internally reflected within the photoluminescent layer and reduce light coupling into the BEF.

[0096] In other embodiments, the photoluminescent layer 152 may be fabricated as a separate film and the resulting film disposed between the light guide 144 and the BEF 154. Fabricating the photoluminescent layer separately may be advantageous when the lower surface of the BEF 154 includes a pattern of features or surface texture.

[0097] For example, in one arrangement, a red or green emitting phosphor and a light transmissive material are deposited as a uniform layer, such as by screen printing, onto a light transmissive film such as, for example, mylar. TM In other embodiments, a red-emitting or green-emitting phosphor may be incorporated into a film and distributed homogeneously throughout the film, which may then be applied to the BEF 154.

[0098] In other embodiments, the photoluminescent layer 152 may be disposed adjacent to the light guide 144. Figure 7 1, a photoluminescent layer 152 is disposed between the light guide 144 and the BEF 154 adjacent to the front emitting surface of the light guide 144 (the upper surface facing the display panel as shown). In some embodiments, the photoluminescent layer 152 may be deposited directly onto the front emitting surface of the light guide 144. An advantage of depositing the photoluminescent layer directly onto the front surface of the light guide is that this may increase the total light emission from the backlight by eliminating an air interface between the light guide and the photoluminescent layer. If such an air interface is present, it may reduce coupling of light from the light guide into the photoluminescent layer and reduce the total light emission from the backlight.

[0099] In other embodiments, the photoluminescent layer 152 may be fabricated as a separate film and the resulting film then applied to the front emitting surface of the light guide 144. This arrangement may be advantageous when the front emitting surface of the light guide 144 includes a pattern of features or texture for aiding uniform light extraction from the light guide.

[0100] In other embodiments and Figure 8 , the photoluminescent layer 152 is disposed between the rear surface of the light guide 144 (the lower surface as shown) and the light reflective layer 150. In some embodiments, the photoluminescent layer 152 may be deposited directly onto the rear surface of the light guide 144. An advantage of depositing the photoluminescent layer directly onto the rear surface of the light guide is that this may increase the total light emission from the backlight by eliminating an air interface between the light guide and the photoluminescent layer. If such an air interface is present, it may reduce coupling of light from the light guide into the photoluminescent layer and reduce the total light emission from the backlight.

[0101] In other embodiments, the photoluminescent layer 152 may be deposited directly onto the light reflective layer 150. An advantage of depositing the photoluminescent layer directly onto the light reflective layer 150 is that this may increase the total light emission from the backlight by eliminating an air interface between the photoluminescent layer and the light reflective layer. If such an air interface is present, it may reduce the reflection of the reverse guided light in the direction toward the light emitting surface 142 of the backlight.

[0102] In still other embodiments, the photoluminescent layer 152 may be fabricated as a separate film and the resulting film then applied to the rear surface of the light guide 144. This arrangement may be advantageous when the rear emitting surface of the light guide 144 includes a pattern of textured features for assisting in uniform light extraction from the light guide.

[0103] An advantage of having a photoluminescent layer compared to known displays utilizing white LEDs is that due to the light diffusing properties of the phosphor material this can eliminate the need for a separate light diffusing layer and associated interface losses and thereby increase display efficiency and reduce production costs.

[0104] However, due to the isotropic nature of photoluminescent light generation, photoluminescent light 158 ​​passing through the red or green emitting phosphor in the photoluminescent layer will be emitted in all directions including towards the light guide 144. To reduce the likelihood of this light reaching the light guide 144, the backlight may further include a light diffusing layer disposed between the photoluminescent layer 152 and the light guide 144.

[0105] Although in the foregoing embodiments the backlight is a side-lit arrangement utilizing a light guide, the present invention may be used in a direct-lit backlight including an array of light emitting devices disposed above the surface of an LC display panel. Fig. 9This embodiment is illustrated in which an array of light emitting devices 146 containing one of a red or green emitting phosphor is provided on a bottom 160 of a light reflective enclosure 162 and a separate photoluminescent layer 152 is provided on the enclosure.

[0106] In any of the described embodiments ( Figures 6 to 8 ), the photoluminescent layer 152 may further incorporate particles of a light scattering (diffusing) material, preferably zinc oxide (ZnO). The light diffusing material may include silicon dioxide (SiO2), titanium dioxide (TiO2), magnesium oxide (MgO), barium sulfate (BaSO4), aluminum oxide (Al2O3), or a combination thereof. The inclusion of a light scattering material may increase the uniformity of light emission from the photoluminescent layer and may eliminate the need for a separate light diffusing layer. Additionally, combining particles of the light scattering material with a red or green emitting phosphor may result in increased light generation by the photoluminescent layer and a substantial reduction in the amount of photoluminescent material required to generate a given color of light, by up to 40%. In view of the relatively high cost of phosphor materials, the inclusion of an inexpensive light scattering material may result in a significant reduction in the manufacturing cost of larger displays, such as tablet computers, laptop computers, TVs, and monitors. Further details of an exemplary method of implementing scattering particles are described in U.S. Pat. No. 8,610,340, issued Dec. 17, 2013, the entirety of which is incorporated herein by reference. The size of the light scattering particles may be selected to scatter relatively more excitation light than light generated by the phosphor.In some embodiments, the light scattering material particles have an average diameter (D50) of 200 nm or less, typically 100 nm to 150 nm.

[0107] As described above, due to the isotropic nature of photoluminescent light generation, photoluminescent light 158 ​​will be emitted in all directions, including in a direction toward light guide 144. To reduce the likelihood of this light reaching light guide 144, the backlight may, in some embodiments, further include a light diffusing layer disposed between photoluminescent layer 152 and light guide 144, even if photoluminescent layer 152 already includes a light scattering material. In other embodiments, photoluminescent layer 152 and the light diffusing layer may be fabricated as separate films and the films then applied to each other.

[0108] Example Color Display Backlight

[0109] Table 4 lists the details of a preferred example backlight according to the present invention for use in a high color gamut LCD television.

[0110] An example backlight preferably includes Figure 7 The side-lit configuration described in .

[0111]

[0112] In the example designated BL.1, the red-emitting phosphor comprises the composition K2SiF6:Mn 4+ (KSF), peak emission wavelength λ pe =632nm narrow band red emitting manganese activated potassium hexafluorosilicate phosphor and positioned in light emitting device 146. Light emitting device 146 includes a 7020 cavity package containing two 300mW GaN LED chips with a dominant emission wavelength of about 453nm. The KSF phosphor is incorporated and homogeneously distributed in a UV curable light transmissive silicone encapsulant (e.g., Dow Corning OE-6370HF optical encapsulant) and the mixture is deposited in the cavity recess to cover the LED chips.

[0113] In BL.1, the green-emitting phosphor comprises a composition of SrGa2S4:Eu, a peak wavelength λ pe =536nm narrow band green emitting strontium gallium sulfide phosphor and positioned in the photoluminescent layer 152. The green emitting phosphor is incorporated and homogeneously distributed in a UV curable light transmissive acrylic binder (UVA4103 from STAR Technology) and the mixture is screen printed as a layer of about 50μm thickness on an about 140μm light transmissive PET (polyethylene terephthalate) film.

[0114] Fig.10 The emission spectrum, intensity (au) versus wavelength (nm), of the light emitting device 146 of BL.1 is shown.

[0115] Fig.11 The emission spectrum, intensity (au) versus wavelength (nm), of the photoluminescent wavelength conversion layer 152 of BL.1 is shown.

[0116] Fig.12 Shown is the emission spectrum, intensity (au) versus wavelength (nm) of backlight BL.1 before and after BEF154.

[0117] Fig.13 The 1931 CIE color coordinates and RGB color coordinates of the NTSC (National Television System Committee) Colorimetry 1953 (CIE1931) standard of the backlight BL.1 are shown.

[0118] Table 5 lists the optical characteristics of backlight BL.1. AUO (AU Optronics Corp.) high color gamut color filter characteristics are used to calculate the red, green, and blue emission spectra of an LCD display incorporating backlight BL.1. As can be seen from Table 5, backlight BL.1 according to the present invention can produce light with a 100.7% color gamut (area) of NTSC and a 104.7% color gamut of the DCI-P3 RGB color space standard. For comparison, known high color gamut LCD displays using phosphors have a DCI-P3 of about 99% to about 100%. More specifically, tests have shown that the backlight according to the present invention has an emission spectrum including red, green and blue light emission peaks, wherein the red light peak has chromaticity coordinates CIE x=0.6700 to 0.6950, CIEy=0.3300 to 0.2950; the green light peak has chromaticity coordinates CIE x=0.1950 to 0.2950, ​​CIE y=0.7250 to 0.6250; and the blue light peak has chromaticity coordinates CIE x=0.1600 to 0.1400, CIE y=0.0180 to 0.0600.

[0119]

[0120]

[0121] Table 6 lists the optical characteristics of backlight BL.2. AUO (AU Optronics Corporation) high color gamut color filter characteristics are used to calculate the red, green, and blue emission spectra of an LCD display incorporating backlight BL.2. As can be seen from Table 6, backlight BL.2 according to the present invention can produce light with a color gamut (area) of 102.2% of NTSC and 106.6% of the DCI-P3 RGB color space standard. Fig.14 The emission spectra, intensity (au) versus wavelength (nm), of backlight BL.2 (tuned to the DCI-P3 white point) before and after the AUO color filter 120 are shown.

[0122]

[0123]

[0124] Table 7 lists the optical characteristics of backlight BL.3. AUO (AU Optronics Corporation) high color gamut color filter characteristics are used to calculate the red, green, and blue emission spectra of an LCD display incorporating backlight BL.3. As can be seen from Table 7, backlight BL.3 according to the present invention can generate light with a color gamut (area) of 112.3% of NTSC and 117.2% of the DCI-P3 RGB color space standard. Fig.15The emission spectra, intensity (au) versus wavelength (nm), of backlight BL.3 (tuned to the DCI-P3 white point) before and after the AUO color filter 120 are shown.

[0125]

[0126]

[0127] More specifically, tests have shown that the backlight according to the present invention has an emission spectrum including red, green and blue light emission peaks, wherein the red light peak has chromaticity coordinates CIE x=0.6700 to 0.6950, CIE y=0.3300 to 0.2950; the green light peak has chromaticity coordinates CIE x=0.1950 to 0.2950, ​​CIE y=0.7250 to 0.6250; and the blue light peak has chromaticity coordinates CIE x=0.1600 to 0.1400, CIE y=0.0180 to 0.0600.

[0128] Table 8 lists RGB color space values ​​of NTSC (National Television System Committee) Colorimetry 1953 (CIE 1931) and DCI-P3 (Digital Cinema Initiative) RGB color space standards.

[0129]

[0130]

[0131] It will be appreciated that the invention is not limited to the particular embodiments described but that variations can be made within the scope of the invention.

[0132] For example, while in the aforementioned embodiments, one or both of the red-emitting and / or green-emitting photoluminescent materials are positioned in a photoluminescent layer, it is contemplated that in further embodiments the red-emitting and / or green-emitting photoluminescent materials are positioned in one or more light-emitting devices thereby eliminating the need for a photoluminescent layer. It has been found that this arrangement is particularly advantageous when the green-emitting photoluminescent material comprises a europium-activated sulfide phosphor. Furthermore, it is also advantageous when the red-emitting photoluminescent material comprises a manganese-activated fluoride phosphor. In some arrangements, the red-emitting and green-emitting photoluminescent materials may be incorporated into the same light-emitting device in the form of a mixture or into separate locations / layers in the same light-emitting device. In other arrangements, the red-emitting and green-emitting photoluminescent materials may be positioned in separate respective light-emitting devices. The inventors have found that this arrangement may increase luminous efficiency and provide the advantages of reduced complexity, ease of manufacture, and reduced manufacturing costs.

[0133] Reference Numbers

[0134] 42: LED chips

[0135] 44: Upper body

[0136] 46: Lower body

[0137] 48: Groove

[0138] 50: Electrical connector

[0139] 52: Electrical connector

[0140] 54: Contact

[0141] 56: Contact pad

[0142] 58: Thermal pad

[0143] 60: Bonding line

[0144] 62: Bonding line

[0145] 100: Color LCD

[0146] 102: LC display panel

[0147] 104: Side-lit backlight

[0148] 106: Front panel

[0149] 108: Back panel

[0150] 110: Liquid crystal (LC)

[0151] 112: Glass Plate

[0152] 114: Watch Surface

[0153] 116: First polarization filter layer

[0154] 118: Anti-reflective layer

[0155] 120: Color filter

[0156] 122: Light-transmitting common electrode plane

[0157] 124: Red sub-pixel filter element

[0158] 126: Green sub-pixel filter element 128: Blue sub-pixel filter element

[0159] 130: Unit pixel

[0160] 132: Opaque separator / black matrix

[0161] 134: Glass Plate

[0162] 136: TFT

[0163] 138: Second polarization filter layer

[0164] 140: White Light

[0165] 142: Backlight luminous surface

[0166] 144: Light Guide

[0167] 146: Light-emitting device

[0168] 148: Composite Light

[0169] 150: Light reflection layer

[0170] 152: Photoluminescence wavelength conversion layer (photoluminescence layer)

[0171] 154: Brightness Enhancement Film (BEF)

[0172] 156: Light diffusion layer

[0173] 158: Photoluminescence

[0174] 160: Bottom of light-reflecting enclosure

[0175] 162: Light reflecting enclosure

[0176] It will be appreciated that the following clauses form part of the disclosure of the invention defined herein. More particularly, the invention may be defined by a combination of features of the clauses as will be detailed below, and the clauses may be used to amend a combination of features within the claims of the present application.

[0177] 1. A display backlight, comprising:

[0178] an excitation source for generating blue excitation light having a main emission wavelength in the range of 445 nm to 465 nm;

[0179] A red photoluminescent material having a peak emission wavelength in the range of 610 nm to 650 nm; and

[0180] Europium activated sulfide phosphor having a peak emission wavelength in the range of 525 nm to 545 nm.

[0181] 2. A backlight according to claim 1, wherein the europium activated sulfide phosphor has a general composition and a crystal structure of MA2S4:Eu, wherein M is at least one of Mg, Ca, Sr and Ba, and A is at least one of Ga, Al, In, La and Y.

[0182] 3. A backlight according to clause 1 or clause 2, wherein the europium activated sulfide phosphor has a general composition and a crystal structure of SrGa2S4:Eu.

[0183] 4. A backlight according to any preceding clause, further comprising a wavelength conversion layer positioned remotely from the excitation source, wherein the wavelength conversion layer comprises at least one of the red photoluminescent material and the europium activated sulfide phosphor.

[0184] 5. The backlight of clause 4, wherein the europium activated sulfide phosphor is positioned in the wavelength conversion layer.

[0185] 6. The backlight of clause 4 or clause 5, wherein the wavelength conversion layer comprises the red photoluminescent material and the europium activated sulfide phosphor.

[0186] 7. A backlight according to any preceding clause, wherein the red photoluminescent material comprises a manganese-activated fluoride phosphor.

[0187] 8. The backlight according to clause 7, wherein the manganese-activated fluoride phosphor comprises the composition K2SiF6:Mn 4 + Manganese-activated potassium hexafluorosilicate phosphor.

[0188] 9. The backlight according to clause 7, wherein the manganese-activated fluoride phosphor comprises the composition K2GeF6:Mn 4 + Manganese-activated potassium hexafluorogermanate phosphor.

[0189] 10. The backlight of clause 7, wherein the manganese-activated fluoride phosphor comprises a phosphor of a composition selected from the group consisting of: K2TiF6:Mn 4+ 、K2SnF6:Mn 4+ 、Na2TiF6:Mn 4+ 、Na2ZrF6:Mn 4+ 、Cs2SiF6:Mn 4+ 、Cs2TiF6:Mn 4+ 、Rb2SiF6:Mn 4+ 、Rb2TiF6:Mn 4+ 、K3ZrF7:Mn 4+ 、K3NbF7:Mn 4+ 、K3TaF7:Mn 4+ 、K3GdF6:Mn 4+ 、K3LaF6:Mn 4+ or K3YF6:Mn 4+ .

[0190] 11. A backlight according to any preceding clause, wherein the red photoluminescent material is positioned in a light emitting device comprising the excitation source.

[0191] 12. A backlight according to any preceding clause, wherein the backlight has an emission spectrum that encompasses at least 95% of the color gamut of the NTSC RGB color space standard.

[0192] 13. A backlight according to any preceding clause, wherein the backlight has an emission spectrum that includes at least 100% of the color gamut of the DCI-P3 RGB color space standard.

[0193] 14. A backlight according to any of the preceding clauses, wherein the backlight has an emission spectrum including red, green and blue light emission peaks, wherein the red light peak has chromaticity coordinates CIE x=0.6700 to 0.6950, CIE y=0.3300 to 0.2950; the green light peak has chromaticity coordinates CIE x=0.1950 to 0.2950, ​​CIE y=0.7250 to 0.6250; and the blue light peak has chromaticity coordinates CIE x=0.1600 to 0.1400, CIE y=0.0180 to 0.0600.

[0194] 15. The backlight of any of clauses 4 to 14, further comprising a light guide, wherein the excitation source is configured to couple light into at least one edge of the light guide and wherein the wavelength conversion layer is disposed adjacent a surface of the wave guide.

[0195] 16. The backlight of clause 15, wherein the wavelength converting layer is in direct contact with the light guide.

[0196] 17. The backlight of clause 15 or clause 16, further comprising a brightness enhancement film, wherein the wavelength conversion layer is disposed between the light guide and the brightness enhancement film.

[0197] 18. The backlight of clause 17, wherein the wavelength conversion layer is in direct contact with the brightness enhancement film.

[0198] 19. The backlight of clause 15 or clause 16, further comprising a light reflective surface, wherein the wavelength converting layer is disposed between the light reflective surface and the light guide.

[0199] 20. The backlight of clause 19, wherein the wavelength converting layer is in direct contact with the light reflecting surface.

[0200] 21. The backlight of any of clauses 4 to 16, further comprising a brightness enhancement film and wherein the wavelength conversion layer is disposed adjacent to the brightness enhancement film.

[0201] 22. The backlight of claim 21, wherein the wavelength conversion layer is in direct contact with the brightness enhancement film.

[0202] 23. A backlight according to any of clauses 4 to 22, wherein the wavelength converting layer comprises particles of light scattering material.

[0203] 24. A backlight according to claim 23, wherein the light scattering material particles are selected from the group consisting of: zinc oxide (ZnO); silicon dioxide (SiO2); titanium dioxide (TiO2); magnesium oxide (MgO); barium sulfate (BaSO4); aluminum oxide (Al2O3) and combinations thereof.

[0204] 25. A backlight according to clause 23 or clause 24, wherein the particles of light scattering material have an average diameter of 200 nm or less.

[0205] 26. A backlight according to any one of clauses 23 to 25, wherein the particles of light scattering material have an average diameter of 100 nm to 150 nm.

[0206] 27. A display backlight, comprising:

[0207] A light emitting device comprising an excitation source for generating blue excitation light having a main emission wavelength in the range of 445 nm to 465 nm and a red photoluminescent material having a peak emission wavelength in the range of 610 nm to 650 nm; and

[0208] A wavelength conversion layer is positioned remotely from the light emitting device; the wavelength conversion layer includes a green photoluminescent material having a peak emission wavelength in the range of 525 nm to 545 nm.

[0209] 28. The backlight of clause 27, wherein the green photoluminescent material comprises a europium activated sulfide phosphor.

[0210] 29. A backlight according to clause 28, wherein the europium activated sulfide phosphor has a general composition and a crystal structure of MA2S4:Eu, wherein M is at least one of Mg, Ca, Sr and Ba, and A is at least one of Ga, Al, In, La and Y.

[0211] 30. The backlight of clause 28 or clause 29, wherein the europium activated sulfide phosphor has a general composition and crystal structure of SrGa2S4:Eu.

[0212] 31. The backlight of clause 27, wherein the green photoluminescent material comprises a quantum dot material.

[0213] 32. A backlight according to any one of clauses 27 to 31, wherein the red photoluminescent material comprises a manganese activated fluoride phosphor.

[0214] 33. A backlight according to clause 32, wherein the manganese-activated fluoride phosphor comprises the composition K2SiF6:Mn 4+ Manganese-activated potassium hexafluorosilicate phosphor.

[0215] 34. The backlight of clause 32, wherein the manganese-activated fluoride phosphor comprises the composition K2GeF6:Mn 4+ Manganese-activated potassium hexafluorogermanate phosphor.

[0216] 35. The backlight of clause 32, wherein the manganese-activated fluoride phosphor comprises a phosphor of a composition selected from the group consisting of: K2TiF6:Mn 4+ 、K2SnF6:Mn 4+ 、Na2TiF6:Mn 4+ 、Na2ZrF6:Mn 4+ 、Cs2SiF6:Mn 4+ 、Cs2TiF6:Mn 4+ 、Rb2SiF6:Mn 4+ 、Rb2TiF6:Mn 4+ 、K3ZrF7:Mn 4+ 、K3NbF7:Mn 4+ 、K3TaF7:Mn 4 + 、K3GdF6:Mn 4+ 、K3LaF6:Mn 4+ or K3YF6:Mn 4+ .

[0217] 36. A backlight according to any of clauses 27 to 35, wherein the backlight has an emission spectrum that encompasses at least 95% of the color gamut of the NTSCRGB color space standard.

[0218] 37. A backlight as described in any of clauses 27 to 36, wherein the backlight has an emission spectrum that includes at least 100% of the color gamut of the DCI-P3 RGB color space standard.

[0219] 38. A backlight according to any one of clauses 27 to 37, wherein the backlight has an emission spectrum including red, green and blue light emission peaks, wherein the red light peak has chromaticity coordinates CIE x=0.6700 to 0.6950, CIE y=0.3300 to 0.2950; the green light peak has chromaticity coordinates CIE x=0.1950 to 0.2950, ​​CIE y=0.7250 to 0.6250; and the blue light peak has chromaticity coordinates CIE x=0.1600 to 0.1400, CIE y=0.0180 to 0.0600.

[0220] 39. A backlight according to any of clauses 27 to 38, further comprising a light guide, wherein the light emitting device is configured to couple light into at least one edge of the light guide and wherein the wavelength conversion layer is disposed adjacent to a surface of the waveguide.

[0221] 40. The backlight of clause 39, wherein the wavelength converting layer is in direct contact with the light guide.

[0222] 41. The backlight of clause 39 or clause 40, further comprising a brightness enhancement film, wherein the wavelength conversion layer is disposed between the light guide and the brightness enhancement film.

[0223] 42. The backlight of clause 41, wherein the wavelength conversion layer is in direct contact with the brightness enhancement film.

[0224] 43. The backlight of clause 39 or clause 40, further comprising a light reflective surface, wherein the wavelength converting layer is disposed between the light reflective surface and the light guide.

[0225] 44. The backlight of clause 43, wherein the wavelength converting layer is in direct contact with the light reflecting surface.

[0226] 45. The backlight of clause 27, further comprising a brightness enhancement film and wherein the wavelength conversion layer is disposed adjacent to the brightness enhancement film.

[0227] 46. ​​The backlight of clause 45, wherein the wavelength converting layer is in direct contact with the brightness enhancement film.

[0228] 47. A backlight according to any of clauses 27 to 46, wherein the wavelength converting layer comprises particles of light scattering material.

[0229] 48. A backlight according to claim 47, wherein the light scattering material particles are selected from the group consisting of: zinc oxide (ZnO); silicon dioxide (SiO2); titanium dioxide (TiO2); magnesium oxide (MgO); barium sulfate (BaSO4); aluminum oxide (Al2O3) and combinations thereof.

[0230] 49. A backlight according to clause 47 or clause 48, wherein the particles of light scattering material have an average diameter of 200 nm or less.

[0231] 50. A backlight according to any one of clauses 47 to 49, wherein the particles of light scattering material have an average diameter of 100 nm to 150 nm.

[0232] 51. A display backlight, comprising:

[0233] A light emitting device comprising an excitation source for generating blue excitation light having a main emission wavelength in the range of 445 nm to 465 nm and a manganese-activated potassium hexafluorosilicate phosphor of the composition K2SiF6:Mn4+; and

[0234] A wavelength conversion layer is positioned remotely from the light emitting device and includes a europium activated sulfide phosphor having a peak emission wavelength in the range of 525 nm to 545 nm.

[0235] 52. A backlight according to clause 51, wherein the europium activated sulfide phosphor has a general composition and a crystal structure MA2S4:Eu, wherein M is at least one of Mg, Ca, Sr and Ba, and A is at least one of Ga, Al, In, La and Y.

[0236] 53. A backlight according to clause 51 or clause 52, wherein the europium activated sulfide phosphor has a general composition and a crystal structure of SrGa2S4:Eu.

[0237] 54. A backlight as described in any of clauses 51 to 53, wherein the backlight has an emission spectrum that includes at least 95% of the color gamut of the NTSCRGB color space standard.

[0238] 55. A backlight as described in any of clauses 51 to 54, wherein the backlight has an emission spectrum that includes at least 100% of the color gamut of the DCI-P3 RGB color space standard.

[0239] 56. A backlight according to any one of clauses 51 to 55, wherein the backlight has an emission spectrum including red, green and blue light emission peaks, wherein the red light peak has chromaticity coordinates CIE x=0.6700 to 0.6950, CIE y=0.3300 to 0.2950; the green light peak has chromaticity coordinates CIE x=0.1950 to 0.2950, ​​CIE y=0.7250 to 0.6250; and the blue light peak has chromaticity coordinates CIE x=0.1600 to 0.1400, CIE y=0.0180 to 0.0600.

[0240] 57. A display backlight, comprising:

[0241] A light emitting device comprising an excitation source for generating blue excitation light having a main emission wavelength in the range of 445 nm to 465 nm and a red photoluminescent material having a peak emission wavelength in the range of 610 nm to 650 nm; and

[0242] A wavelength conversion layer is positioned remotely from the light emitting device, the wavelength conversion layer comprising a green photoluminescent material having a peak emission wavelength in the range of 525 nm to 545 nm, the green photoluminescent material comprising a quantum dot material.

Claims

1. A display backlight, characterized in that: include: an excitation source for generating light having a wavelength of maximum intensity in the range of 445 nm to 465 nm; and A light-transmitting medium, comprising: K2SiF6:Mn 4+ or K2GeF6:Mn 4+ , for generating light having a wavelength of maximum intensity in the range of 610 nm to 650 nm; and A green phosphor for producing light with a wavelength having a maximum intensity in the range of 525nm to 545nm; wherein the green phosphor has a general composition and a crystal structure MA2S4:Eu, wherein M is at least one of Mg, Ca, Sr and Ba, and A is at least one of Ga, Al, In, La and Y.

2. The display backlight according to claim 1, characterized in that: The K2SiF6:Mn 4+ Or the K2GeF6:Mn 4+ and the green phosphor may be incorporated into the light-transmitting medium as a mixture.

3. The display backlight according to claim 1, characterized in that: The K2SiF6:Mn 4+ Or the K2GeF6:Mn 4+ and the green phosphor may be incorporated into the light-transmitting medium as respective separate layers.

4. The display backlight according to claim 2 or 3, characterized in that: The display backlight includes a package that accommodates the excitation source and the light-transmitting medium.

5. The display backlight according to claim 2 or 3, characterized in that: The green phosphor is used to generate light having a wavelength with a maximum intensity within a range of 530 nm to 545 nm, or to generate light having a wavelength with a maximum intensity within a range of 535 nm to 540 nm, or to generate light having a wavelength with a maximum intensity of 535 nm.

6. The display backlight according to claim 2 or 3, characterized in that: The green phosphor has the following general composition: (M)(A)2S4:Eu,M',A', wherein M is at least one of Mg, Ca, Sr and Ba; M' is at least one of Li, Na and K; A is at least one of Ga, Al and In; and A' is at least one of Si, Ge, La, Y and Ti; or (M,M')(A,A')2S4:Eu, wherein M is at least one of Mg, Ca, Sr and Ba; M' is at least one of Li, Na and K; A is at least one of Ga, Al, In, La and Y; and A' is at least one of Si, Ge and Ti; wherein in the MA2S4 crystal lattice, M' replaces M and A' replaces A; or SrGa2S4:Eu.

7. The display backlight according to claim 2 or 3, characterized in that: The display backlight is used to generate light with an emission spectrum including red light, green light and blue light emission peaks; wherein the red light peak has chromaticity coordinates CIE x=0.6700~0.6950, CIE y=0.3300~0.2950; the green light peak has chromaticity coordinates CIE x=0.1950~0.2950, ​​CIE y=0.7250~0.6250; the blue light peak has chromaticity coordinates CIE x=0.1600~0.1400, CIE y=0.0180~0.0600.

8. The display backlight according to claim 2 or 3, characterized in that: The display backlight has an emission spectrum with a color gamut that includes at least one of: at least 95% of the NTSC RGB color space standard, and at least 100% of the DCI-P3 RGB color space standard.

9. A display backlight, characterized in that: include: an excitation source for generating light having a wavelength of maximum intensity in the range of 445 nm to 465 nm; and Wavelength conversion phosphor film, comprising: A light-transmitting medium, comprising: K2SiF6:Mn 4+ or K2GeF6:Mn 4+ , for generating light having a wavelength of maximum intensity in the range of 610 nm to 650 nm; and A green phosphor for producing light having a wavelength with a maximum intensity in the range of 525 nm to 545 nm; wherein the green phosphor has a general composition and a crystal structure of MA2S4:Eu, wherein M is at least one of Mg, Ca, Sr and Ba, and A is at least one of Ga, Al, In, La and Y; Wherein, the wavelength conversion phosphor film is located at a remote location from the excitation source.

10. The display backlight according to claim 9, characterized in that: The K2SiF6:Mn 4+ Or the K2GeF6:Mn 4+ and the green phosphor may be incorporated into the light-transmitting medium as a mixture.

11. The display backlight according to claim 9, characterized in that: The K2SiF6:Mn 4+ Or the K2GeF6:Mn 4+ and the green phosphor may be incorporated into the light-transmitting medium as respective separate layers.

12. The display backlight according to claim 10 or 11, characterized in that: The green phosphor is used to generate light having a wavelength with a maximum intensity within a range of 530 nm to 545 nm, or to generate light having a wavelength with a maximum intensity within a range of 535 nm to 540 nm, or to generate light having a wavelength with a maximum intensity of 535 nm.

13. The display backlight according to claim 10 or 11, characterized in that: The green phosphor has the following general composition: (M)(A)2S4:Eu,M',A', wherein M is at least one of Mg, Ca, Sr and Ba; M' is at least one of Li, Na and K; A is at least one of Ga, Al and In; and A' is at least one of Si, Ge, La, Y and Ti; or (M,M')(A,A')2S4:Eu, wherein M is at least one of Mg, Ca, Sr and Ba; M' is at least one of Li, Na and K; A is at least one of Ga, Al, In, La and Y; and A' is at least one of Si, Ge and Ti; wherein in the MA2S4 crystal lattice, M' replaces M and A' replaces A; or SrGa2S4:Eu.

14. The display backlight according to claim 10 or 11, characterized in that: The display backlight also includes a light guide, wherein the excitation source is configured to couple light into at least one edge of the light guide and wherein the wavelength conversion phosphor film is disposed adjacent a surface of the light guide.

15. The display backlight according to claim 10 or 11, characterized in that: The display backlight also includes a brightness enhancement film, wherein the wavelength conversion phosphor film is disposed adjacent to the brightness enhancement film or the wavelength conversion phosphor film is in direct contact with the brightness enhancement film.

16. The display backlight according to claim 10 or 11, characterized in that: The display backlight is used to generate light with an emission spectrum including red light, green light and blue light emission peaks; wherein the red light peak has a chromaticity coordinate CIEx=0.6700~0.6950, CIE y=0.3300~0.2950; the chromaticity coordinate of the green light peak is CIE x=0.1950~0.2950, ​​CIE y=0.7250~0.6250; the chromaticity coordinate of the blue light peak is CIE x=0.1600~0.1400, CIE y=0.0180~0.0600.

17. The display backlight according to claim 10 or 11, characterized in that: The display backlight has an emission spectrum with a color gamut that includes at least one of: at least 95% of the NTSC RGB color space standard, and at least 100% of the DCI-P3 RGB color space standard.

Images