LED package having improved color gamut, and display panel comprising same

Abstract

The present invention relates to an LED package having an improved color gamut and, more specifically, to an LED package for achieving a wide color gamut in a display device, the LED package comprising: a phosphor composition part containing a red phosphor; and a light-emitting device including blue light and green light, thereby enabling realization of a wide color gamut.

Description

LED package with an enhanced color reproduction range, display panel including the same

[0001] The present invention relates to an LED package having an enhanced color reproduction range, and more specifically, to an LED package for a wide range of color reproduction of a display device, comprising a phosphor composition part including a red phosphor and a light-emitting element including blue light and green light, thereby enabling a wide range of color reproduction.

[0002] Backlight units of flat-panel displays, such as LCD TVs, primarily use LED light sources as the light source for the backlight unit. A typical LED package includes a cavity for mounting a light-emitting element, leads for connecting the light-emitting element to an external electrical circuit, bonding wires for electrical connection between the light-emitting element and the leads, and a molding portion that protects the LED chip by being molded within the cavity using a transparent resin material such as epoxy or silicone.

[0003] Semiconductor devices containing compounds such as GaN and AlGaN have wide and easily adjustable band gap energies, so they are used in various ways, such as light-emitting diodes and various other diodes.

[0004] In particular, light-emitting diodes (LEDs) using group 3-5 or group 2-6 compound semiconductor materials can realize various colors such as red, green, blue, and ultraviolet light through the development of thin-film growth technology and device materials, and can also realize high-efficiency white light by using fluorescent materials or combining colors, and have the advantages of low power consumption, semi-permanent lifespan, fast response speed, safety, and environmental friendliness compared to conventional light sources such as fluorescent lamps and incandescent lamps.

[0005] Methods for realizing white light using such light-emitting devices include using a single chip and using a multi-chip.

[0006] More specifically, when white light is implemented with a single chip, there is a method of obtaining white light by using light emitted from a blue LED to excite at least one phosphor, and a method of combining a phosphor on a blue or ultraviolet (UV) light-emitting diode chip, and when white light is implemented with a multi-chip, there is a method of obtaining white light by combining three types of chips of RGB (Red, Green, Blue).

[0007] Currently, the display market is seeing growth in the OLED sector due to its high color quality and color reproduction rate. To meet this growing demand, technical alternatives to LED light sources are facing the technical requirement to significantly improve color reproduction rates compared to existing technologies.

[0008] Efforts to overcome the color reproduction rate of LCD display devices have continued since the 2020s by incorporating inks and materials utilizing additional quantum dot materials into light guide plates, prism sheets, and diffusion sheets, but this has led to an increase in the price of LCD TVs and caused complexity in the structure of LCD TVs.

[0009] Furthermore, in order to overcome these issues, some quantum dot LED packages have been developed by incorporating quantum dot materials into LED packages; however, they have not yet been commercialized because they have failed to overcome the reliability issues under high temperature and high humidity conditions, which are limitations of quantum dot materials.

[0010] Under these circumstances, currently commercialized white light LED packages are formed and used with a structure consisting of a combination of a 'blue light emitting element (compound semiconductor) + green light phosphor + red light phosphor,' but they have the limitations described below.

[0011] To improve the color reproduction rate of LED light sources, the color realization range of the white light source of the LED must be enhanced, and currently, LED packages formed by mixing green light phosphors and red light phosphors on a blue light chip are being used.

[0012] Figure 1 is a diagram showing the color reproduction range of a conventional LED package.

[0013] Figure 1 is a Yxy color coordinate, where the two-dot dashed line represents the defined color space of CIE1931, the thick solid line represents the NTSC color reproduction range, and the normal solid line represents the color reproduction range of a conventional LED package.

[0014] Conventional LED packages produce white light using a combination of a green phosphor and a red phosphor in a blue light-emitting element, but the color reproduction rate (NTSC) of the white light source produced in this way is about 90%, which is very low compared to OLED.

[0015] Referring to Fig. 1, it can be seen that in order to improve the color reproduction rate in a conventional LED package, the emission wavelength of the green phosphor must be shifted to a wider area, as indicated by the arrow in Fig. 1, that is, from a wavelength of 550 nm to around 530 to 545 nm, in order to satisfy a more improved color reproduction range.

[0016] However, conventional green phosphors do not shift their emission wavelength toward a wider range as shown in Fig. 1, making it difficult to improve color reproduction rate; therefore, the development of a new technology to solve this problem is necessary. The present invention is related to this.

[0017] The technical problem that the present invention aims to solve is to secure improved wide-range color reproduction in an LED package for wide-range color reproduction of a display device by shifting green light from a wavelength of 550 nm to a wavelength of 530 to 545 nm in order to improve the color reproduction rate in a conventional LED package.

[0018] The technical problems of the present invention are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art from the description below.

[0019] The LED package having an enhanced color reproduction range according to the present invention for solving the above technical problem is an LED package for wide-range color reproduction of a display device, and may include a phosphor composition part including a red phosphor and a light-emitting element including blue light and green light.

[0020] In some embodiments of the present invention, the wavelength band of the blue light may be in the range of 430 to 450 nm.

[0021] In some embodiments of the present invention, the wavelength band of the green light may be in the range of 530 to 550 nm.

[0022] In some embodiments of the present invention, the light-emitting element may include a blue light-emitting layer and a green light-emitting layer between a P-type GaN layer and an N-type GaN layer.

[0023] In some embodiments of the present invention, an interference reduction layer may be included between the blue emission layer and the green emission layer.

[0024] In some embodiments of the present invention, the wavelength band of the red phosphor may be in the range of 610 to 650 nm and the full width at half maximum may be 50 nm or less.

[0025] The display panel of the present invention for solving the above technical problem may include an LED package for wide range color reproduction.

[0026] The LED package having an enhanced color reproduction range according to the present invention can satisfy a color reproduction range of 100% according to DCI standards and 97% according to NTSC standards in the color space defined by CIE1931 by forming a display device using an LED package that includes a phosphor composition part including a red phosphor and a light-emitting element including blue light and green light simultaneously. With a 6-7% improvement in color reproduction range compared to conventional LED packages, the performance of display devices using backlights can be dramatically improved, and manufacturing costs can be lowered by avoiding the need for a complex structure or the use of expensive quantum dot materials.

[0027] Figure 1 is a diagram showing the color reproduction range of a conventional LED package.

[0028] FIG. 2 is a cross-sectional view of an LED package according to one embodiment of the present invention.

[0029] FIG. 3 is a perspective view showing a light-emitting element according to FIG. 2.

[0030] Figure 4 is a diagram showing the characteristics of the blue light of the light-emitting element according to Figure 2.

[0031] Figure 5 is a diagram showing the characteristics of the green light of the light-emitting element according to Figure 2.

[0032] Figure 6 is a diagram showing the frequency characteristics of a light-emitting element according to Figure 2.

[0033] Figure 7 is a diagram showing the color reproduction range of the LED package of the present invention.

[0034] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0035] "And / or" includes each of the mentioned items and all combinations of one or more.

[0036] The terms used herein are for describing embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, "comprising" and / or "comprising" does not exclude the presence or addition of one or more other components, steps, actions, and / or elements to the mentioned components, steps, actions, and / or elements.

[0037] Furthermore, throughout the specification, when a part is described as being "connected" to another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly" or "electrically connected" with other members or elements in between.

[0038] Additionally, throughout the specification, the description that each layer (film), region, pattern, or structure is formed "on" or "under" the substrate, each layer (film), region, pad, or pattern includes both direct formation and formation through another layer. The criteria for "on" or "under" each layer are described based on the drawings.

[0039] In addition, expressions such as 'first, second,' etc., to distinguish multiple compositions

[0040] It is an expression used solely for that purpose and does not limit the order or other characteristics between the components.

[0041] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0042] FIG. 2 is a cross-sectional view of an LED package according to one embodiment of the present invention, and FIG. 3 is a perspective view showing a light-emitting element according to FIG. 2.

[0043] Referring to FIG. 2 and FIG. 3, the LED package (100) according to the present invention is an LED package for wide-range color reproduction of a display device and may include a phosphor composition part (30) including a red phosphor (31) and a light-emitting element (70) including blue light and green light.

[0044] The phosphor composition part (30) may include a red phosphor (31), and the red phosphor (31) may include one or more types of phosphors. For example, the red phosphor (31) may include a KSF phosphor (chemical formula K2SiF6 : Mn4+).

[0045] The wavelength band of the red phosphor (31) is in the range of 610 to 650 nm, and the full width at half maximum may be 50 nm or less.

[0046] Referring to FIG. 2, an LED package (100) according to one embodiment of the present invention may include a body (11), a plurality of lead frames (21, 23), a phosphor composition part (30), and a light-emitting element (70).

[0047] The body (11) can be formed of a material having a reflectance higher than the transmittance for a wavelength emitted by a light-emitting element (70), such as a material having a reflectance of 70% or more.

[0048] The body (11) may include a silicone-based, epoxy-based, or plastic material as a resin-based insulating material, or may be formed of a thermosetting resin or a material with high heat resistance and high light resistance.

[0049] The body (11) may include a cavity that is recessed to a predetermined depth from the upper surface of the body (11) and has an open top. The cavity has a width that gradually widens as it rises, which can improve light emission efficiency.

[0050] A plurality of lead frames, such as first and second lead frames (21, 23), may be disposed on the body (11). A portion of the first lead frame (21) and the second lead frame (23) may be exposed to the outside of the body (11) and may be mounted and connected on a circuit board to receive power.

[0051] The first lead frame (21) and the second lead frame (23) may include at least one of a conductive metal material, for example, titanium (Ti), copper (Cu), nickel (Ni), gold (Au), chromium (Cr), tantalum (Ta), platinum (Pt), tin (Sn), silver (Ag), and phosphorus (P).

[0052] A light-emitting element (70) may be disposed in the center of the lower part of the cavity, and the light-emitting element (70) may be connected to the lead frame (21, 23) by a connecting member (27). The connecting member (27) may include a conductive material, such as a metal wire.

[0053] Referring to FIG. 3, a light-emitting element (70) according to one embodiment of the present invention may include a P-pole contact layer (71), a P-type GaN layer (72), a blue light emission layer (73), an interference reduction layer (74), a green light emission layer (75), an N-type GaN layer (78), and an N-pole contact layer (79).

[0054] The P-pole contact layer (71) and the N-pole contact layer (79) can be connected to the first lead frame (21) and the second lead frame (23) by a connecting member (27), and the first lead frame (21) and the second lead frame (23) can be connected to the power terminal and the ground terminal on the circuit board, respectively.

[0055] The P-type GaN layer (72) can provide a void necessary for the flow of current for light emission, and the N-type GaN layer (78) can provide electrons necessary for the flow of current for light emission.

[0056] The blue light emitting layer (73) is a multiple quantum structure layer that emits blue light, and the green light emitting layer (75) is a multiple quantum structure layer that emits green light.

[0057] The interference reduction layer (74) can reduce interference between the multiple quantum structure layer emitting blue light and the multiple quantum structure layer emitting green light.

[0058] The wavelength range of the blue light of the light-emitting element (70) formed in this way is in the range of 430 to 450 nm, and the wavelength range of the green light may be in the range of 530 to 550 nm.

[0059] Figure 4 is a diagram showing the characteristics of blue light of a light-emitting element according to Figure 2, where the horizontal axis represents frequency in nm and the vertical axis represents light output in mW or full width in nm.

[0060] Referring to Figure 4, the output of blue light decreases from 750mW to 720mW (solid line) as the wavelength changes from 435nm to 460nm, and the full width at half maximum increases from 16.5nm to 19.5nm (dashed line).

[0061] It can be confirmed that the impact on color reproduction is not significant because the decrease in luminance and the increase in full width are not substantial.

[0062] Figure 5 is a diagram showing the characteristics of green light of a light-emitting element according to Figure 2, where the horizontal axis represents frequency in nm and the vertical axis represents light output in mW or full width in nm.

[0063] Referring to Figure 5, the output of green light decreases from 140mW to 115mW (solid line) as the wavelength changes from 525nm to 540nm, and the full width at half maximum increases from 29nm to 34.5nm (dashed line).

[0064] Since the decrease in output is significant as the wavelength increases, the necessity of limiting the wavelength used can be confirmed.

[0065] The wavelength band of the green light of the light-emitting element (70) formed in this way may be in the range of 530 to 550 nm.

[0066] Therefore, the wavelength band of the green light of the light-emitting element (70) can be used as the light-emitting element (70) of the present invention while accepting a reduction in brightness in the range of 530 to 550 nm.

[0067] However, if such a reduction in the brightness of the green light cannot be accepted, the wavelength band of the green light can be managed to be a narrower range, namely 530 to 535 nm, to form a light-emitting element (70).

[0068] Figure 6 is a diagram showing the frequency characteristics of a light-emitting element according to Figure 2, where the horizontal axis represents frequency in nm and the vertical axis represents light output.

[0069] In this case, the dashed line represents the characteristics of a conventional light-emitting element, and the solid line represents the characteristics of a light-emitting element according to one embodiment of the present invention.

[0070] As previously mentioned, in a conventional LED package, in order to improve color reproduction, the emission wavelength of green light must be shifted to a wider area (shifted from light with a wavelength of 550 nm to light with a wavelength of 530 to 550 nm), as indicated by the arrow in FIG. 1. Referring to FIG. 6, it can be seen that the green light according to the present invention shifts from light with a wavelength of 550 nm to light with a wavelength of 540 nm.

[0071] In addition, since a smaller full width at half maximum is advantageous for reproducing a wide range of colors, it can be confirmed that the full width at half maximum of the green light of the LED package according to the present invention is reduced from 55 nm to 32 nm, thereby contributing to reproducing a wide range of colors.

[0072] As such, it can be seen that the green light of the LED package according to the present invention acts favorably for color reproduction over a wide range of both wavelength and full width at half maximum.

[0073] FIG. 7 is a diagram showing the color reproduction range of an LED package according to the present invention. FIG. 7 is a Yxy color coordinate, where the two-dot dashed line represents the color space defined by CIE1931, the thick solid line represents the NTSC color reproduction range, the normal solid line represents the color reproduction range of a conventional LED package, and the dotted line represents the color reproduction range of an LED package according to the present invention.

[0074] In addition, the xy color coordinates and color reproduction range in the display state are shown in the table below.

[0075]

[0076] DISPLAY Status Red Green Blue NTSC(%) xy xy xy The present invention 0.659 30.290 10.210 70.668 90.156 30.03 189 6.8 Conventional 0.657 60.290 70.256 70.659 40.156 90.04 68 9.4

[0077] Referring to Figure 7 and Table 1, it can be seen that conventional LED packages have a low color reproduction rate (NTSC) of approximately 90% for white light sources. In the LED package according to the present invention, it can be seen that the emission wavelength of green light is shifted to a wider direction, that is, from light with a wavelength of 550 nm to light with a wavelength of 530 to 540 nm, as indicated by the arrow in Figure 1.

[0078] The LED package according to the present invention has a color reproduction rate (NTSC) of approximately 97% for a white light source, and it can be confirmed that the color reproduction rate is significantly improved by 7% compared to conventional LED packages, thereby achieving a groundbreaking improvement in color reproduction over a wide range.

[0079] Thus, the LED package having an improved color reproduction range according to the present invention can significantly improve the performance of a display device using a backlight by forming a display device using an LED package that includes a phosphor composition including a red phosphor and a light-emitting element including blue light and green light simultaneously, with a color reproduction range improved by about 6 to 7% compared to a conventional LED package.

[0080] A plurality of LED packages having an enhanced color reproduction range according to the present invention may be arrayed on a substrate, and optical members such as a light guide plate, a prism sheet, and a diffusion sheet may be disposed on the light path of the light-emitting element package.

[0081] Additionally, it may be implemented as a light source device including an LED package according to the present invention. The light source device may include a bottom cover, a reflector disposed on the bottom cover, a light-emitting module that emits light and includes a semiconductor element, a light guide plate disposed in front of the reflector and guiding the light emitted from the light-emitting module forward, an optical sheet including prism sheets disposed in front of the light guide plate, a display panel disposed in front of the optical sheet, an image signal output circuit connected to the display panel and supplying an image signal to the display panel, and a color filter disposed in front of the display panel. Here, the bottom cover, the reflector, the light-emitting module, the light guide plate, and the optical sheet may form a backlight unit.

[0082] Although the present invention has been described with respect to some embodiments as above, those skilled in the art will recognize that it may be implemented in other forms while maintaining the technical spirit and essential features of the invention.

[0083] The scope of the rights of the present invention shall be determined primarily by the claims; however, all modifications or variations derived from configurations directly derived from the descriptions in the claims, as well as configurations equivalent thereto, shall be interpreted as being included within the scope of the rights of the present invention.

Claims

1. As an LED package for wide-range color reproduction of a display device, Phosphor composition part including a red phosphor; and An LED package including a light-emitting element including blue light and green light.

2. In Paragraph 1, An LED package in which the wavelength band of the blue light is in the range of 430 to 450 nm.

3. In Paragraph 1, An LED package in which the wavelength band of the above green light is in the range of 530 to 550 nm.

4. In Paragraph 1, The above light-emitting element is an LED package comprising a blue emission layer and a green emission layer between a P-type GaN layer and an N-type GaN layer.

5. In Paragraph 4, An LED package comprising an interference reduction layer between the blue emission layer and the green emission layer.

6. In Paragraph 1, An LED package having a wavelength band of the above red phosphor in the range of 610 to 650 nm and a full width at half maximum of 50 nm or less.

7. A display panel comprising an LED package according to any one of claims 1 to 6.

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