Light-emitting element and lighting device comprising this element

Abstract

A light-emitting element (10) comprising: a base plate (101); a first light-emitting diode (102), a second light-emitting diode (103), and a third light-emitting diode (104), each arranged on the base plate (101), wherein the light-emitting diode (102), the second light-emitting diode (103), and the third light-emitting diode (104) are capable of emitting a first blue light having a wavelength in the range of 410 nm to 450 nm, a second blue light having a wavelength in the range of 450 nm to 470 nm, and a third blue light having a wavelength in the range of 460 nm to 490 nm, respectively; and three phosphor layers (105) each covering a surface of the first light-emitting diode (102), a surface of the second light-emitting diode (103) and a surface of the third light-emitting diode (104), wherein the three phosphor layers (105) are excited by the first blue light, the second blue light and the third blue light, respectively, after absorbing the first blue light, the second blue light and the third blue light, respectively, to emit predetermined lights, such that when the predetermined lights are mixed with each other, the light-emitting element (10) emits a white light.

Description

[0001] The present disclosure relates to a light-emitting element and a lighting device, and more particularly to a light-emitting element capable of emitting white light and a lighting device including the light-emitting element and capable of adjusting the color and brightness of the light.

[0002] Fig. Figure 1 is a spectral diagram of white light emitted by a conventional light-emitting element. The aforementioned white light has a continuous spectrum, a wavelength of 380 nm to 780 nm, and a hue that can be modulated into reddish white light, yellowish white light, or bluish white light depending on the color temperature. Since the white light emitted by the conventional light-emitting element does not have a bluish-green hue (see arrow in Fig.1), the color rendering indices R9 and R12 generally do not exceed 90, which means that this white light cannot simulate sunlight. Therefore, experts are striving to develop a light-emitting element capable of emitting white light that simulates sunlight.

[0003] Fig. Figure 2 is a CIE chromaticity diagram showing the color coordinates of two light-emitting elements in a conventional lighting device. That is, the conventional lighting device typically includes a first light-emitting element with a low color temperature and a second light-emitting element with a high color temperature. As shown in Fig.2, the color coordinates of the first light-emitting element and the second light-emitting element are represented by the coordinates 91 and 92, respectively. By adjusting the brightness of the first light-emitting element and / or the second light-emitting element, the color temperature of a resulting mixed light moves along a line connecting the coordinate 91 and the coordinate 92 (i.e., the color temperature shown in Fig. 1), whereby the conventional lighting device can emit light with a predetermined color temperature.

[0004] However, in the CIE chromaticity diagram of the aforementioned conventional lighting device, only the two endpoints of the line connecting the coordinate 91 of the first light-emitting element and the coordinate 92 of the second light-emitting element lie on a blackbody radiation locus 80 (i.e., the curve representing the color temperature of a light source similar to sunlight), while other line segments of this line, in particular the central light segment, lie relatively far from the blackbody radiation locus 80. In other words, the color temperature of the resulting mixed light determined based on the CIE chromaticity diagram differs significantly from the color temperature of actual sunlight.

[0005] An object of the present disclosure is therefore to provide a light-emitting element and a lighting device including the light-emitting element that can overcome at least one of the disadvantages of the prior art.

[0006] According to one aspect of the present disclosure, the light-emitting element comprises a bottom plate, a first light-emitting diode, a second light-emitting diode, a third light-emitting diode, and three phosphor layers. The first light-emitting diode, the second light-emitting diode, and the third light-emitting diode are each arranged on the bottom plate and are capable of emitting a first blue light having a wavelength in the range of 410 nm to 450 nm, a second blue light having a wavelength in the range of 450 nm to 470 nm, and a third blue light having a wavelength in the range of 460 nm to 490 nm, respectively. The three phosphor layers each cover a surface of the first light-emitting diode, a surface of the second light-emitting diode, and a surface of the third light-emitting diode. The three phosphor layers are formed after the first blue light, the second blue light, and the third blue light are absorbed by the first blue light, the second blue light, and the third blue light, respectively.the third blue light is excited to emit predetermined lights respectively, so that the light-emitting element emits a white light when the predetermined lights are mixed together.

[0007] According to another aspect of the present disclosure, the lighting device comprises a light source unit and a control unit. The light source unit comprises at least three of the aforementioned light-emitting elements. In a CIE chromaticity diagram, the color coordinates of the at least three light-emitting elements are defined as a first coordinate, a second coordinate, and a third coordinate, respectively. The at least three light-emitting elements have different correlated color temperatures. In the CIE chromaticity diagram, a first line has three line segments, each of which connects two corresponding coordinates of the first, second, and third coordinates. The first line intersects a blackbody radiation locus and encloses and defines a first color region. A portion of the blackbody radiation locus is located within the first color region.In the CIE chromaticity diagram, a color coordinate of a light mixed by the at least three light-emitting elements is defined as a mixed light coordinate. The control unit is electrically connected to the light source unit such that the mixed light coordinate moves within the first color range when the light source unit supplies electrical energy to the light source unit to control the brightness of each of the at least three light-emitting elements.

[0008] Further features and advantages of the present disclosure will become apparent from the following detailed description of the embodiment(s) with reference to the accompanying drawings. It should be noted that various features may not be drawn to scale. Fig.Figure 1 is a spectral diagram illustrating the changes in relative light intensity at different wavelengths of white light emitted from a conventional light-emitting element. Fig. 2 is a CIE chromaticity diagram showing the color coordinates of a first light-emitting element and a second light-emitting element of a conventional lighting device. Fig. 3 is a block diagram showing the configuration of a lighting device according to a first embodiment of the present disclosure. Fig. 4 is a schematic view showing the arrangement of the light-emitting elements of the lighting device according to the first embodiment of the present disclosure. Fig. 5 is a schematic view showing the configuration of one of the light-emitting elements. Fig.6 is a spectral diagram illustrating changes in relative light intensity at different wavelengths of a white light emitted from the light-emitting element of the lighting device. Fig. 7 is a diagram showing changes in correlated color temperature at different ambient temperatures of a white light emitted from the light-emitting element according to the first embodiment and a white light emitted from the conventional light-emitting element. Fig. 8 is a graph showing changes in the color rendering index R9 at different ambient temperatures of a white light emitted from the light-emitting element according to the first embodiment and a white light emitted from the conventional light-emitting element. Fig.9 is a graph showing changes in the color rendering index R12 at different ambient temperatures of a white light emitted from the light-emitting element according to the first embodiment and a white light emitted from the conventional light-emitting element. Fig. 10 is a CIE chromaticity diagram showing the color coordinates of a first white light source group, a second white light source group, and a third white light source group of the lighting device according to the first embodiment of the present disclosure. Fig. 11 is a block diagram showing the configuration of a lighting device according to a second embodiment of the present disclosure. Fig.12 is a CIE chromaticity diagram showing the color coordinates of the first white light source group, the second white light source group, and the third white light source group, as well as the color coordinates of a red light source group, a green light source group, and a blue light source group of the lighting device according to the second embodiment of the present disclosure.

[0009] Before describing the present disclosure in more detail, it should be noted that, where appropriate, reference numerals or end portions of reference numerals have been repeated in the figures to identify corresponding or analogous elements which may optionally have similar characteristics.

[0010] It should be noted that, for clarity of description, spatially relative terms such as "top," "bottom," "upper," "lower," "upon," "above," "over," "downward," "upward," and the like may be used throughout the disclosure while referring to the features illustrated in the drawings. The features may be oriented differently (e.g., rotated 90 degrees or in other orientations), and the spatially relative terms used herein may be interpreted accordingly.

[0011] Referring to the Fig. 3 and Fig.4, a lighting device according to a first embodiment of the present disclosure includes a light source unit 1, a control unit 2 electrically connected to the light source unit 1, and a substrate 3 on which the light source unit 1 is disposed. Examples of lighting devices may include photographic lamps, recessed ceiling lamps, desk lamps, plant cultivation lamps, etc.

[0012] The light source unit 1 comprises a first white light source group 11, a second white light source group 12 and a third white light source group 13, which are capable of emitting white light (see Fig.3). In other words, in the first embodiment, each of the first white light source group 11, the second white light source group 12, and the third white light source group 13 is configured to emit white light. The first white light source group 11, the second white light source group 12, and the third white light source group 13 have different correlated color temperatures. Each of the first white light source group 11, the second white light source group 12, and the third white light source group 13 includes a plurality of light-emitting elements 10 (see Fig.4). The light-emitting elements 10 of the first white light source group 11, the light-emitting elements 10 of the second white light source group 12, and the light-emitting elements 10 of the third white light source group 13 are arranged offset on the substrate 3 in an overall slightly circular pattern. The offset arrangement of the light-emitting elements 10 of the first white light source group 11, the second white light source group 12, and the third white light source group 13 enables uniform mixing of the light emitted by these light-emitting elements 10. It should be noted that the orientation and overall pattern of the light-emitting elements 10 are not limited to a specific arrangement. In certain embodiments, the orientation and overall pattern of the light-emitting elements 10 may differ from those shown in Fig.4. Note that the number of light-emitting elements 10 in each of the first white light source group 11, the second white light source group 12, and the third white light source group 13 can be changed according to actual requirements. In certain embodiments, each of the first white light source group 11, the second white light source group 12, and the third white light source group 13 includes only one light-emitting element 10, that is, the light source unit 1 includes three light-emitting elements 10 corresponding to the first white light source group 11, the second white light source group 12, and the third white light source group 13.

[0013] Referring to Fig.5, each of the light-emitting elements 10 comprises a base plate 101, a first light-emitting diode 102, a second light-emitting diode 103, and a third light-emitting diode 104, each arranged on the base plate 101, and three phosphor layers 105, each covering a surface of the light-emitting diode 102, a surface of the second light-emitting diode 103, and a surface of the third light-emitting diode 104. The first light-emitting diode 102, the second light-emitting diode 103, and the third light-emitting diode 104 are essentially light-emitting diode components.More specifically, the first light-emitting diode 102 is capable of emitting a first blue light with a wavelength in the range of 410 nm to 450 nm, the second light-emitting diode 103 is capable of emitting a second blue light with a wavelength in the range of 450 nm to 470 nm, and the third light-emitting element 104 is capable of emitting a third blue light with a wavelength in the range of 460 nm to 490 nm (not shown in the figures). The first blue light, the second blue light, and the third blue light each have a color temperature in the range of 2700 K to 7500 K.

[0014] The three phosphor layers 105 contain phosphor powders of different colors. The types and composition ratio of the phosphor powders vary depending on the wavelengths of the first blue light, the second blue light, and the third blue light emitted by the first light-emitting diode 102, the second light-emitting diode 103, and the third light-emitting diode 104, respectively, and can be adjusted as needed.

[0015] Referring to Fig.6, the three phosphor layers 105, after absorbing the first blue light, the second blue light, and the third blue light, respectively, are excited by the first blue light, the second blue light, and the third blue light to emit predetermined lights, respectively, so that when the predetermined lights are mixed with each other, the light-emitting element 10 emits a white light having a sufficient bluish-green hue, whereby the white light can simulate sunlight.

[0016] With the above configuration, the white light emitted by the light-emitting element 10 has a very high color rendering index (CRI) (i.e., a quantitative measurement of the ability of a light source to display the real colors of objects, abbreviated as CRI). Specifically, the white light emitted by the light-emitting element 10 has a color rendering index R1 to R15 of more than 90. In particular, when the light-emitting element 10 has a correlated color temperature of 5886 K, the white light emitted by the light-emitting element 10 has color rendering indices R9 and R12 of more than 93, which improves the effect of reproducing the real colors of objects. The measured values of the color rendering indices Ra and R1 to R15 for the white light emitted from the light-emitting element 10 of this embodiment at the correlated color temperature of 5886 K are shown in Table 1 below. Table 1 Color rendering index Ra R1 R2 R3 R4 R5 R6 R7 Measured value 98 99 99 96 97 99 98 97 Color rendering index R8 R9 R10 R11 R12 R13 R14 R15 Measured value 97 99 96 98 96 99 97 98

[0017] Fig. 7 is a graph showing changes in the correlated color temperature at different ambient temperatures of a white light emitted from the light-emitting element 10 according to the first embodiment and a white light emitted from a conventional light-emitting element. The change in the correlated color temperature of the white light emitted from the light-emitting element 10 according to the first embodiment is represented by a solid line therein, while the change in the correlated color temperature of the white light emitted from the conventional light-emitting element is represented by a dashed line therein. As in Fig.7, the correlated color temperature of the white light emitted from the light-emitting element 10 according to the first embodiment is significantly less affected by the ambient temperature compared to the correlated color temperature of the white light emitted from the conventional light-emitting element.

[0018] Fig.8 is a graph showing changes in the color rendering index R9 at different ambient temperatures of a white light emitted from the light-emitting element 10 according to the first embodiment and a white light emitted from the conventional light-emitting element. The change in the color rendering index R9 of the white light emitted from the light-emitting element 10 according to the first embodiment is represented by a solid line therein, while the change in the color rendering index R9 of the white light emitted from the conventional light-emitting element is represented by a dashed line therein. As in Fig.8, the color rendering index R9 of the white light emitted from the light-emitting element 10 is constantly greater than 91 at an ambient temperature in the range of 30°C to 90°C, which indicates that the color rendering index R9 of the white light emitted from the light-emitting element 10 according to the first embodiment is significantly less affected by the ambient temperature compared to the color rendering index R9 of the white light emitted from the conventional light-emitting element.

[0019] Fig.9 is a graph showing changes in the color rendering index R12 at different ambient temperatures of a white light emitted from the light-emitting element according to the first embodiment and a white light emitted from the conventional light-emitting element, wherein the change in the color rendering index R12 of the white light emitted from the light-emitting element 10 according to the first embodiment is represented by a solid line therein, while the change in the color rendering index R12 of the white light emitted from the conventional light-emitting element is represented by a dashed line therein. As in Fig. As shown in Fig. 9, the color rendering index R12 of the white light emitted by the light-emitting element 10 is constantly greater than 91 at an ambient temperature in the range of 30°C to 90°C.

[0020] According to the Fig. 3, Fig. 4 and Fig.10, in a CIE chromaticity diagram, the chromaticity coordinate of the light-emitting element(s) 10 in the first white light source group 11 is defined as a first coordinate 112, the chromaticity coordinate of the light-emitting element(s) 10 in the second white light source group 12 is defined as a second coordinate 122, and the chromaticity coordinate of the light-emitting element(s) 10 in the third white light source group 13 is defined as a third coordinate 132. In this embodiment, the CIE chromaticity diagram is a CIE 1976 chromaticity diagram. Since the light-emitting element(s) 10 in the first white light source group 11, the light-emitting element(s) 10 in the second white light source group 12, and the light-emitting element(s) 10 in the third white light source group 13 are each a CIE 1976 chromaticity diagram, the chromaticity coordinate of the light-emitting element(s) 10 in the first white light source group 11, the light-emitting element(s) 10 in the second white light source group 12, and the light-emitting element(s) 10 in the third white light source group 13 are each a CIE 1976 chromaticity diagram.the light-emitting elements 10 in the third white light source group 13 have different correlated color temperatures, the first coordinate 112, the second coordinate 122 and the third coordinate 132 represent different correlated color temperatures. As in . Fig.10, in the CIE chromaticity diagram, a first line having three first line segments, each of which connects two corresponding ones of the first coordinate 112, the second coordinate 122, and the third coordinate 132, intersects a blackbody radiation locus 41. At least two of the first coordinate 112, the second coordinate 122, and the third coordinate 132 are not located on the blackbody radiation locus 41. In this embodiment, the first coordinate 112, the second coordinate 122, and the third coordinate 132 are not located on the blackbody radiation locus 41. However, if one of the first coordinate 112 and the third coordinate 132 is located on the blackbody radiation locus 41, the object of the present disclosure can be achieved.

[0021] According to the present disclosure, the correlated color temperature of the first coordinate 112 ranges from 1600 K to 2600 K, the correlated color temperature of the second coordinate 122 ranges from 2600 K to 4500 K, and the correlated color temperature of the third coordinate 132 ranges from 8000 K to 20000 K. In other words, the correlated color temperature of the light-emitting element(s) 10 in the first white light source group 11 ranges from 1600 K to 2600 K, the correlated color temperature of the light-emitting element(s) 10 in the second white light source group 12 ranges from 2600 K to 4500 K, and the correlated color temperature of the light-emitting element(s) 10 in the third white light source group 13 ranges from 8000 K to 20000 K. In this embodiment, as in Fig.10, the correlated color temperature of the light-emitting elements 10 in the first white light source group 11 is 1800 K, the correlated color temperature of the light-emitting element(s) 10 in the second white light source group 12 is 3500 K, and the correlated color temperature of the light-emitting element(s) 10 in the third white light source group 13 is 10000 K.

[0022] As in Fig.10, the first line intersects the blackbody radiation locus 41 at two intersection points 18, and the color temperature of one of the two intersection points 18 (i.e., the intersection point 18 closer to the first coordinate 112) is not greater than 1800 K, while the color temperature of the other of the two intersection points 18 (i.e., the intersection point 18 closer to the third coordinate 132) is not less than 10000 K. In other words, a light mixed by the first white light source group 11, the second white light source group 12, and the third white light source group 13 has a correlated color temperature in the range of 1800 K to 10000 K. As shown in Fig.10, in this embodiment, the color temperature of one of the two intersection points 18 (i.e., the intersection point 18 closer to the first coordinate 112) is not greater than 2200 K, while the color temperature of the other of the two intersection points 18 (i.e., the intersection point 18 closer to the third coordinate 132) is not less than 8500 K. Furthermore, in this embodiment, one of the three first line segments connecting the first coordinate 112 and the third coordinate 132 intersects the blackbody radiation location 41 at the two intersection points 18, but is not limited thereto. In other embodiments, the intersection points 18 are the locations where each two of the three first line segments intersect the blackbody radiation location 41.The first line connecting the first coordinates 112, the second coordinates 122, and the third coordinates 132 encloses and defines a first color range 42, and a portion of the blackbody radiation locus 41 is located within the first color range 42. That is, the portion of the blackbody radiation locus 41 located within the first color range 42 serves as a target for light adjustment. As shown in FIG. Fig. 10, in the CIE chromaticity diagram, a color coordinate of a light mixed by the light-emitting element(s) 10 in the first white light source group 11, the light-emitting element(s) 10 in the second white light source group 12, and the light-emitting element(s) 10 in the third white light source group 13 is defined as a mixed light coordinate 17.

[0023] The control unit 2 is electrically connected to the light source unit 1, so that when the control unit 2 supplies electrical energy (e.g., electric current) to the light source unit 1 to control the brightness of each of the first white light source unit group 11, the second white light source unit group 12, and the third white light source unit group 13, the mixed light coordinate 17 moves within the first color range 42 in accordance with the change in brightness thereof, thereby enabling the mixing of lights with different correlated color temperatures ranging from 1800 K to 10000 K. An example of the control unit 2 includes a combination of a microprocessor, a storage device such as a memory, and a current driver.The control unit 2 is capable of outputting a drive current to the first white light source group 11, the second white light source group 12, and the third white light source group 13 according to a predetermined algorithm to control their brightness. The predetermined algorithm, obtained based on the spectra of the first white light source group 11, the second white light source group 12, and the third white light source group 13, is used to determine the power distribution between the first white light source group 11, the second white light source group 12, and the third white light source group 13 (e.g., a power ratio of the first white light source group 11, the second white light source group 12, and the third white light source group 13 is 35:63:3) corresponding to a target color temperature of the mixed light (e.g., 3000 K).Such a predetermined algorithm is stored in the control unit 2 in the form of a function or a table to indicate the relationship between the target color temperature of the mixed light and the power ratios of the first, second, and third white light source groups 11, 12, 13. For example, if a power of 300 W is determined to be applied to the light source unit 1, this power can be distributed to the first white light source group 11 (35%), the second white light source group 12 (63%), and the third white light source group 13 (3%) according to the aforementioned power ratio to emit the mixed light with the predetermined color temperature (3000 K). Therefore, the brightness of the light emitted by the first, second, and third white light source groups 11, 12, 13 can be varied by the power distributed to the first, second, and third white light source groups 11, 12, 13.

[0024] In this embodiment, the percentages of the power ratio of the first white light source group 11, the second white light source group 12, and the third white light source group 13 for each of the correlated color temperatures of the mixed light determined by the algorithm are shown in Table 2 below.

[0025] As shown in Table 2, the D uvvalue (i.e., a color deviation between the color coordinate and the blackbody radiation locus 41) for each of the mixed lights among the correlated color temperatures of 2000 K to 8500 K (i.e., the target color temperatures) is in the range of -0.0005 to 0.0005, and the color rendering index (CRI) value (i.e., a quantitative measurement of the ability of a light source to represent the real colors of objects) for the same is greater than 95. In this embodiment, the mixed light coordinate 17 of the light mixed by the first white light source group 11, the second white light source group 12, and the third white light source group 13 is located on or near the blackbody radiation locus 41. Thus, the light mixed by the light source unit 1 is highly similar to sunlight, thus achieving the effect of reproducing the real colors of objects. Table 2 Correlated color temperature First white light source group 1800 K Second white light source group 3500K Third white light source group 10000 K D uv -Value CRI value 2000K 96% 1% 3% 0.0002 95.23 2200K 86% 13% 2% 0.0000 97.57 2400K 74% 26% 1% -0.0001 97.77 2600K 59% 40% 1% -0.0001 97.83 2700K 53% 47% 2% 0.0000 97.92 2800K 47% 53% 2% -0.0001 97.94 3000K 35% 63% 3% 0.0000 97.94 3200K 27%s 69% 6% 0.0000 97.76 3400K 20% 73% 8% 0.0001 97.72 3600K 15% 76% 11% -0.0001 97.57 3800K 11% 77% 14% 0.0001 97.62 4000K 8% 77% 18% 0.0000 97.58 4200K 5% 75% 22% 0.0001 97.66 4300K 4% 75% 23% 0.0001 97.67 4500K 2% 71% 27% 0.0000 97.67 4700K 1% 68% 31% 0.0001 97.79 4900K 0% 66% 37% 0.0001 97.89 5000K 0% 64% 38% 0.0000 97.99 5300K 0% 55% 46% -0.0001 97.91 5600K 0% 48% 53% -0.0002 97.78 5700K 0% 46% 56% -0.0002 97.70 6000K 0% 40% 62% -0.0001 97.62 6500K 0% 31% 71% -0.0001 97.37 7000K 1% 21% 80% -0.0001 97.27 7500K 2% 14% 85% 0.0000 97.35 8000K 4% 7% 92% 0.0000 97.27 8500K 5% 2% 94% 0.0000 97.45 9000K 4% 0% 99% 0.0017 98.36 9500K 2% 0% 100% 0.0031 98.26 10000K 0% 0% 103% 0.0042 97.47

[0026] The lighting device according to a second embodiment of the present disclosure will be described with reference to Fig. 11 and Fig. 12. The configuration of the lighting device of the second embodiment is substantially similar to that of the lighting device of the first embodiment, except that in the second embodiment, the light source unit 1 further includes a red light source group 14, a green light source group 15, and a blue light source group 16 (see Fig.11), each capable of emitting red light, green light, and blue light. That is, in the second embodiment, in addition to the first white light source group 11, the second white light source group 12, and the third white light source group 13, each emitting white light, the red light source group 14, the green light source group 15, and the blue light source group 16, each emitting red light, green light, and blue light, are also included. The red light source group 14 includes a plurality of red LEDs (not shown), the green light source group 15 includes a plurality of green LEDs (not shown), and the blue light source group 16 includes a plurality of blue LEDs (not shown).In addition, the red light source group 14, the green light source group 15 and the blue light source group 16 are each configured to emit a monochromatic light having a full width at half maximum (FWHM) in the range of 5 nm to 30 nm.

[0027] In this embodiment, the red light source group 14, the green light source group 15, and the blue light source group 16 are electrically connected to the control unit 2, so that when the control unit 2 supplies electrical power to the light source unit 1, the red light source group 14, the green light source group 15, and the blue light source group 16 each receive currents of different values, so that the brightness of the monochromatic light emitted from each of the red light source group 14, the green light source group 15, and the blue light source group 16 can be changed by the control unit 2.

[0028] In the CIE chromaticity diagram according to Fig.12 is the color coordinate of the red light source group 14 as the fourth coordinate 141, the color coordinate of the green light source group 15 as the fifth coordinate 151 and the color coordinate of the blue light source group 16 as the sixth coordinate 161 . As in Fig. 12, a second line has three second line segments, each of which connects two corresponding coordinates of the fourth coordinate 141, the fifth coordinate 151, and the sixth coordinate 161. The second line encloses and defines a second color region 43, and an area of the second color region 43 is larger than an area of the first color region 42.

[0029] In practical applications, the power ratio of the first white light source group 11, the second white light source group 12, and the third white light source group 13 is first adjusted by the control unit 2 so that the light control unit 1 supplies a mixed light serving as the basic light, the color coordinate of which is close to the blackbody radiation location 41. Subsequently, the power ratio of the red light source group 14, the green light source group 15, and the blue light source group 16 is adjusted by the control unit 2 as needed to adjust the color and brightness of the basic light. Thus, the lighting device of the second embodiment can be used for various purposes, such as photography, etc.For example, when the illumination device of this embodiment is used in photography to simulate a reddish sunset-like light, a basic light whose color coordinate is close to the blackbody radiation locus 41 is first obtained, and then the brightness of the red light source group 14 is adjusted according to the desired saturation of a red light, whereby the illumination device can emit the reddish sunset-like light after the red light is added to the basic light.

[0030] In summary, by including the first light-emitting diode 102, the second light-emitting diode 103, and the third light-emitting diode 104, which emit a first blue light having a wavelength in the range of 410 nm to 450 nm, a second blue light having a wavelength in the range of 450 nm to 470 nm, and a third blue light having a wavelength in the range of 460 nm to 490 nm, respectively, the three phosphor layers 105, after absorbing the first blue light, the second blue light, and the third blue light, are excited by the first blue light, the second blue light, and the third blue light, respectively, to emit predetermined lights, respectively, so that when the predetermined lights are mixed with each other, the light-emitting element 10 of the present disclosure emits a white light having a sufficient bluish-green hue, whereby the white light can simulate sunlight.

[0031] By including the light-emitting elements 10 with different correlated color temperatures and a portion of the blackbody radiation locus 41 located within the first color range 42 in the CIE chromaticity diagram, and with the brightness of each of the light-emitting elements 10 controlled by the control unit 2, the mixed light coordinate 17 of a light mixed by the light-emitting elements 10 is located at or near the blackbody radiation locus 41 within the first color range 42. Thus, the light emitted by the light source unit 1 of the lighting device of the present disclosure is substantially similar to sunlight. As such, the lighting device of the present disclosure achieves the effect of reproducing the real colors of objects.

[0032] Furthermore, by further incorporating the red, green, and blue light source groups 14, 15, 16 and obtaining the basic light whose color coordinate is close to the blackbody radiation locus 41, the power ratio of the red, green, and blue light source groups 14, 15, 16 is adjusted as needed to adjust the color and brightness of the basic light. Therefore, the color saturation of an emitted light obtained after light mixing can be improved, taking into account that this emitted light has a good color rendering property. As such, the lighting device of the present disclosure is suitable for use in photography or other applications in various environments.

[0033] In the above description, for purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiment(s). However, one skilled in the art will appreciate that one or more other embodiments may be practiced without some of these specific details. It should also be understood that reference throughout this description to "an embodiment," "embodiment," an embodiment by ordinal number, etc., means that a particular feature, structure, or characteristic may be included in the practice of the disclosure. In the description, various features are sometimes grouped into a single embodiment, figure, or description to streamline the disclosure and facilitate understanding of various inventive aspects; this does not imply that each of these features must be practiced with the presence of all other features.In other words, if the implementation of one or more features or specific details does not interfere with the implementation of one or more other features or specific details, then the one or more features may be singled out and implemented alone without the other or other features or specific details. It should further be noted that one or more features or specific details from one embodiment may be practiced together with one or more features or specific details from another embodiment where appropriate in the practice of the disclosure.

Claims

[1] A light-emitting element (10) comprising: a base plate (101); a first light-emitting diode (102), a second light-emitting diode (103), and a third light-emitting diode (104), each arranged on the base plate (101), wherein the light-emitting diode (102), the second light-emitting diode (103), and the third light-emitting diode (104) are capable of emitting a first blue light having a wavelength in the range of 410 nm to 450 nm, a second blue light having a wavelength in the range of 450 nm to 470 nm, and a third blue light having a wavelength in the range of 460 nm to 490 nm, respectively; and three phosphor layers (105) each covering a surface of the first light-emitting diode (102), a surface of the second light-emitting diode (103) and a surface of the third light-emitting diode (104), wherein the three phosphor layers (105) are excited by the first blue light, the second blue light and the third blue light, respectively, after absorbing the first blue light, the second blue light and the third blue light, respectively, to emit predetermined lights, such that when the predetermined lights are mixed with each other, the light-emitting element (10) emits a white light. [2] The light-emitting element (10) according to claim 1, wherein the first blue light, the second blue light and the third blue light each have a color temperature in the range of 2700 K to 7500 K. [3] The light-emitting element (10) according to claim 1, wherein the white light emitted by the light-emitting element (10) has a color rendering index R9 of more than 91 at an ambient temperature in the range of 30°C to 90°C. [4] The light-emitting element (10) according to claim 1, wherein the white light emitted by the light-emitting element (10) has a color rendering index R12 of more than 91 at an ambient temperature in the range of 30°C to 90°C. [5] A lighting device comprising: a light source unit (1) having at least three light-emitting elements (10), each of which is designed according to claim 1, wherein in a CIE chromaticity diagram, the color coordinates of the at least three light-emitting elements (10) are each defined as a first coordinate (112), a second coordinate (122) and a third coordinate (132), the at least three light-emitting elements (10) have different correlated color temperatures, in the CIE chromaticity diagram, a first line has three line segments, each of which connects two corresponding coordinates of the first coordinate (112), the second coordinate (122) and the third coordinate (132), the first line intersecting a blackbody radiation locus (41) and enclosing and defining a first color region (42), a part of the blackbody radiation locus (41) lying within the first color region (42), in the CIE chromaticity diagram, a color coordinate of a light mixed by the at least three light-emitting elements (10) is defined as a mixed light coordinate (17); and a control unit (2) electrically connected to the light source unit (1) such that when the control unit (2) supplies electrical energy to the light source unit (1) to control the brightness of each of the at least three light-emitting elements (10), the mixed light coordinate (17) moves within the first color range (42). [6] The lighting device according to claim 5, wherein at least two of the first coordinate (112), the second coordinate (122) and the third coordinate (132) do not lie on the blackbody radiation location (41). [7] Lighting device according to claim 5, wherein the first coordinate (112), the second coordinate (122) and the third coordinate (132) do not lie on the blackbody radiation location (41). [8] Lighting device according to claim 5, wherein the first line intersects the blackbody radiation location (41) at two intersection points (18), wherein a color temperature of one of the two intersection points (18) is not greater than 1800 K and the color temperature of the other of the two intersection points (18) is not less than 10000 K [9] Lighting device according to claim 5, wherein one of the three first line segments connecting the first coordinate (112) and the third coordinate (132) intersects the blackbody radiation location (41) at two intersection points (18), wherein a color temperature of one of the two intersection points (18) is not greater than 1800 K and the color temperature of the other of the two intersection points (18) is not less than 10000 K. [10] The lighting device according to claim 5, wherein a correlated color temperature of the first coordinate (112) is in the range of 1600 K to 2600 K. [11] The lighting device of claim 10, wherein a correlated color temperature of the second coordinate (122) is in the range of 2600 K to 4500 K. [12] The lighting device of claim 11, wherein a correlated color temperature of the third coordinate (132) is in the range of 8000 K to 20000 K. [13] The lighting device according to claim 5, further comprising a substrate (3), wherein the at least three light-emitting elements (10) are arranged in a staggered orientation on the substrate (3). [14] The lighting device according to claim 5, wherein the light source unit (1) further comprises a red light source group (14), a green light source group (15), and a blue light source group (16) capable of emitting red light, green light, and blue light, respectively, wherein the red light source group (14), the green light source group (15), and the blue light source group (16) are electrically connected to the control unit (2), so that when the control unit (2) supplies the electrical power to the light source unit (1), the brightness of each of the red light source group (14), the green light source group (15), and the blue light source group (16) can be changed by the control unit (2). [15] Lighting device according to claim 14, wherein in the CIE chromaticity diagram, the color coordinates of the red light source group (14), the green light source group (15) and the blue light source group (16) are defined as a fourth coordinate (141), a fifth coordinate (151) and a sixth coordinate (161), respectively, a second line has three second line segments, each of which connects two corresponding coordinates of the fourth coordinate (141), the fifth coordinate (151) and the sixth coordinate (161) and encloses and defines a second color area (43), and an area of the second color area (43) is larger than an area of the first color area (42).

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