Lighting device

Abstract

To provide a lighting device which can easily control the color rendering of light.SOLUTION: A lighting device 10 comprises: a first light emission device 1a; a plurality of second light emission devices 1b; and a control part 7. The first light emission device 1a has a first peak wavelength in a wavelength region of 360 to 430nm, and has a first light emission spectrum in which the light intensity continuously reduces as directed to each of a shorter wavelength and a longer wavelength than the first peak wavelength. Each of the plurality of second light emission devices has a second peak wavelength in a wavelength region of 360 to 430nm, a third peak wavelength in a wavelength region from a longer wavelength than the second peak wavelength to 750nm, and a second light emission spectrum in which the light intensity continuously reduces as directed to a shorter wavelength than the second peak wavelength and a longer wavelength than the third peak wavelength. The control part 7 controls the first light emission device 1a and the plurality of second light emission devices 1b. The third peak wavelengths in the plurality of second light emission devices 1b are difference.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] This disclosure relates to a lighting device. [Background technology]

[0002] In recent years, lighting devices that use semiconductor light-emitting diodes (LEDs) as light sources have been replaced by fluorescent lamps and incandescent bulbs. Furthermore, lighting devices that use light-emitting diodes as light sources are also used for visual inspection of painted surfaces on products such as home appliances and automobiles.

[0003] Semiconductor light-emitting elements have a narrow wavelength band for their synchrotron radiation and can only emit light of a single color. To obtain white light as illumination, multiple semiconductor light-emitting elements with different wavelength bands for their synchrotron radiation are prepared, and white light is achieved by mixing the colors of the multiple synchrotron radiation sources. Alternatively, multiple phosphors that emit fluorescence with different wavelength bands when excited by the same wavelength of light are prepared, and white light is achieved by mixing the synchrotron radiation from the semiconductor light-emitting elements with the fluorescence emitted by the multiple phosphors excited by the synchrotron radiation from the semiconductor light-emitting elements. By using such color mixing methods, light sources with spectra other than white light can be produced according to the purpose (see Japanese Patent Publication No. 2015-126160).

[0004] However, the technology disclosed in Patent Document 1 did not describe or even anticipate the control of the luminescence intensity and emission spectrum of the lighting device. [Overview of the Initiative]

[0005] An illumination device according to one embodiment of the present disclosure comprises a first light-emitting device, a plurality of second light-emitting devices, and a control unit. The first light-emitting device has a first emission spectrum having a first peak wavelength in the wavelength region of 360 to 430 nm, and in which the light intensity decreases continuously as the wavelength approaches shorter and longer wavelengths, respectively, than the first peak wavelength. Each of the plurality of second light-emitting devices has a second peak wavelength in the wavelength region of 360 to 430 nm, and a third peak wavelength in the wavelength region from longer wavelengths than the second peak wavelength to 750 nm, and in which the light intensity decreases continuously as the wavelength approaches shorter wavelengths than the second peak wavelength and longer wavelengths than the third peak wavelength, respectively, and has a second emission spectrum. The control unit controls the first light-emitting device and the plurality of second light-emitting devices. Each of the plurality of second light-emitting devices has a different third peak wavelength.

[0006] Furthermore, in one embodiment of the present disclosure, the emission spectrum has an excitation peak wavelength in the 360 ​​nm to 430 nm wavelength region and an emission peak wavelength in the 610 nm to 730 nm wavelength region. In addition, when the light intensity at the emission peak wavelength is set to 1, the relative light intensity at the excitation peak wavelength is 0.05 to 0.3, the relative light intensity in the 440 nm to 480 nm region is 0.1 or less, and the light intensity in the wavelength region from 480 nm to the emission peak wavelength increases continuously. [Brief explanation of the drawing]

[0007] [Figure 1] This is an external perspective view of a light-emitting device according to an embodiment of the present disclosure. [Figure 2] This is a cross-sectional view of the light-emitting device shown in Figure 1, when it is cut along the plane indicated by the dashed line. [Figure 3] Figure 2 is a magnified view of the light-emitting device shown. [Figure 4] This is a graph showing the emission spectrum of each light-emitting device in the embodiments of this disclosure. [Figure 5] This is a graph showing the spectrum of externally emitted light in the lighting device of the embodiment of the present disclosure. [Figure 6]This is a graph showing the spectrum of externally emitted light in an embodiment of the present disclosure of a light-emitting device and / or illumination device. [Figure 7] This is a graph showing the spectrum of externally emitted light in an embodiment of the present disclosure of a light-emitting device and / or illumination device. [Figure 8] This is a graph showing the spectrum of externally emitted light in an embodiment of the present disclosure of a light-emitting device and / or illumination device. [Figure 9] This is an external perspective view of a lighting device equipped with a light-emitting device according to an embodiment of this disclosure. [Figure 10] This is an exploded perspective view of a lighting device according to an embodiment of the present disclosure. [Figure 11] This is a perspective view showing the light-transmitting substrate removed from the housing of the lighting device according to the present disclosure. [Figure 12] This is a diagram showing the configuration of a lighting device according to an embodiment of the present disclosure. [Figure 13] This is a cross-sectional view showing the configuration of a lighting device according to another embodiment of the present disclosure. [Modes for carrying out the invention]

[0008] The light-emitting device and lighting device according to the embodiments of this disclosure will be described below with reference to the drawings.

[0009] <Configuration of light-emitting device and illumination device> Figure 1 is an external perspective view of a light-emitting device according to an embodiment of the present disclosure. Figure 2 is a cross-sectional view of the light-emitting device shown in Figure 1 when it is cut along a plane indicated by dashed lines. Figure 12 is a configuration diagram of a lighting device according to an embodiment of the present disclosure. In these figures, the lighting device 10 comprises a first light-emitting device 1a, a plurality of second light-emitting devices 1b, and a control unit 7. The first light-emitting device 1a and the second light-emitting devices 1b each comprise a substrate 2, a light-emitting element 3, a frame 4, a sealing member 5, and a wavelength conversion member 6.

[0010] The light-emitting element 3 is located on the substrate 2. The frame 4 is located on the substrate 2, surrounding the light-emitting element 3. The sealing member 5 is filled into the inner space enclosed by the frame 4, leaving a portion of the upper part of the space enclosed by the frame 4 vacant. The wavelength conversion member 6 is housed within the frame 4, along the upper surface of the sealing member 5, in the upper part of the inner space enclosed by the frame 4. The light-emitting element 3 is, for example, an LED (Light Emitting Diode) or an LD (Laser Diode), which emits light outward when electrons and holes in a pn junction using a semiconductor recombine.

[0011] The substrate 2 is a substrate mainly composed of an insulating material, which is, for example, a ceramic material such as alumina or mullite, or a glass ceramic material. Alternatively, it is composed of a composite material obtained by mixing several of these materials. Furthermore, the substrate 2 can be a polymer resin in which metal oxide fine particles that can adjust the thermal expansion of the substrate 2 are dispersed.

[0012] At least the upper surface or interior of the substrate 2 is provided with wiring conductors that electrically conduct electricity between the inside and outside of the substrate 2. The wiring conductors are made of conductive materials such as tungsten, molybdenum, manganese, or copper. If the substrate 2 is made of a ceramic material, for example, a metal paste obtained by adding an organic solvent to powder such as tungsten is printed in a predetermined pattern onto a ceramic green sheet that will become the substrate 2. After this, multiple ceramic green sheets are laminated and fired to obtain the substrate. In addition, a plating layer of, for example, nickel or gold is formed on the surface of the wiring conductors to prevent oxidation. Furthermore, a metal reflective layer may be positioned on the upper surface of the substrate 2, spaced apart from the wiring conductors and the plating layer, in order to efficiently reflect light upwards on the substrate 2. The metal reflective layer is made of, for example, aluminum, silver, gold, copper, or platinum.

[0013] The light-emitting element 3 is mounted on the main surface of the substrate 2. The light-emitting element 3 is electrically connected via, for example, a brazing material or solder, on a plating layer adhered to the surface of a wiring conductor formed on the upper surface of the substrate 2. The light-emitting element 3 has a translucent substrate and a semiconductor light layer formed on the translucent substrate. The translucent substrate may be any substrate as long as it can grow the semiconductor light layer using a chemical vapor deposition method such as metalorganic vapor phase epitaxy or molecular beam epitaxy. As the material used for the translucent substrate, for example, sapphire, gallium nitride, aluminum nitride, zinc oxide, zinc selenide, silicon carbide, silicon or zirconium diboride can be used. The thickness of the translucent substrate is, for example, 50 μm or more and 1000 μm or less.

[0014] The semiconductor light layer is composed of a first semiconductor layer formed on the translucent substrate, a light-emitting layer formed on the first semiconductor layer, and a second semiconductor layer formed on the light-emitting layer. The first semiconductor layer, the light-emitting layer, and the second semiconductor layer can use, for example, group III nitride semiconductors, group III-V semiconductors such as gallium phosphide or gallium arsenide, or group III nitride semiconductors such as gallium nitride, aluminum nitride or indium nitride. The thickness of the first semiconductor layer is, for example, 1 μm or more and 5 μm or less, the thickness of the light-emitting layer is, for example, 25 nm or more and 150 nm or less, and the thickness of the second semiconductor layer is, for example, 50 nm or more and 600 nm or less. Further, the light-emitting element 3 configured as such can emit excitation light in a wavelength range of, for example, 280 nm or more and 450 nm or less.

[0015] The frame body 4 is made of, for example, a ceramic material such as aluminum oxide, titanium oxide, zirconium oxide or yttrium oxide, or a porous material, or a resin material mixed with a powder composed of a metal oxide such as aluminum oxide, titanium oxide, zirconium oxide or yttrium oxide. The frame body 4 is connected to the main surface of the substrate 2 via, for example, a resin, a brazing material or solder. The frame body 4 is provided on the main surface of the substrate 2 so as to surround the light-emitting element 3 with a gap therebetween. Further, the inclined inner wall surface of the frame body 4 is formed so as to expand outward as it moves away from the main surface of the substrate 2. And the inner wall surface of the frame body 4 functions as a reflection surface for the excitation light emitted from the light-emitting element 3. In addition, when the shape of the inner wall surface of the frame body 4 is circular in plan view, the light emitted from the light-emitting element 3 can be uniformly reflected outward by the reflection surface.

[0016] Further, for the inclined inner wall surface of the frame body 4, for example, a metal layer made of tungsten, molybdenum, manganese, etc. and a plating layer made of nickel, gold, etc. covering the metal layer may be formed on the inner peripheral surface of the frame body 4 made of a sintered material. This plating layer has a function of reflecting the light emitted by the light-emitting element 3. Note that the inclination angle of the inner wall surface of the frame body 4 is set at an angle of, for example, 55 degrees or more and 70 degrees or less with respect to the main surface of the substrate 2.

[0017] The inner space surrounded by the substrate 2 and the frame body 4 is filled with a light-transmissive sealing member 5. The sealing member 5 seals the light-emitting element 3 and extracts the light emitted from the inside of the light-emitting element 3 to the outside. Further, it has a function of allowing the light extracted to the outside of the light-emitting element 3 to pass through. The sealing member 5 is filled in the inner space surrounded by the substrate 2 and the frame body 4 while leaving a part of the space surrounded by the frame body 4. The sealing member 5 is made of, for example, a light-transmissive insulating resin such as a silicone resin, an acrylic resin or an epoxy resin, or a light-transmissive glass material. The refractive index of the sealing member 5 is set at, for example, 1.4 or more and 1.6 or less.

[0018] The wavelength conversion member 6 is located in the upper part of the inner space enclosed by the substrate 2 and the frame 4, along the upper surface of the sealing member 5. The wavelength conversion member 6 is formed to fit within the frame 4. The wavelength conversion member 6 has the function of converting the wavelength of light emitted by the light-emitting element 3. That is, light emitted from the light-emitting element 3 enters the interior of the wavelength conversion member 6 through the sealing member 5. At that time, the phosphor contained inside is excited by the light emitted from the light-emitting element 3 and emits fluorescence from the phosphor. It also transmits and radiates a portion of the light from the light-emitting element 3. The wavelength conversion member 6 is made of a translucent insulating resin such as fluororesin, silicone resin, acrylic resin, or epoxy resin, or a translucent glass material, and the phosphor is contained in the insulating resin or glass material. The phosphor is uniformly dispersed in the wavelength conversion member 6. The phosphor contained in the light-emitting element 3 and the wavelength conversion member 6 is selected so that the emission spectrum of the light emitted from the light-emitting device 1 becomes the emission spectrum shown in Figure 4.

[0019] As shown in Figure 5, the first light-emitting device 1a of the embodiment of this disclosure uses a light-emitting element 3 whose first peak wavelength λ1 is in the range of 360 to 430 nm. The second light-emitting device 1b uses a light-emitting element 3 that emits excitation light whose second peak wavelength λ2 is in the range of 360 to 430 nm. In other words, the second peak wavelength λ2 is the peak wavelength of the excitation light. Furthermore, the second light-emitting device 1b may have a third peak wavelength λ3 in the wavelength range from a longer wavelength than the second peak wavelength λ2 to 750 nm when the excitation light is irradiated onto a phosphor, for example, the third peak wavelength λ3 is emitted in the wavelength range of 410 to 750 nm. In this case, each of the multiple second light-emitting devices 1b uses at least a part of different phosphors. A phosphor that emits blue fluorescence, a phosphor that emits blue-green fluorescence, a phosphor that emits green fluorescence, a phosphor that emits red fluorescence, and a phosphor that emits fluorescence in the near-infrared region may be used. Alternatively, these phosphors may be mixed together.

[0020] Each phosphor is, for example, a blue phosphor is BaMgAl 10 O 17: Eu, (Sr, Ca, Ba) 10 (PO4)6Cl2: Eu, (Sr, Ba) 10 (PO4)6Cl2: Eu, a phosphor showing cyan color, is (Sr, Ba, Ca)5(PO4)3Cl: Eu, Sr4Al 14 O 25 : Eu. Phosphors showing green color are SrSi2(O, Cl)2N2: Eu, (Sr, Ba, Mg)2SiO4: Eu 2+ , ZnS: Cu, Al, Zn2SiO4: Mn. As phosphors showing red color, there are Y2O2S: Eu, Y2O3: Eu, SrCaClAlSiN3: Eu 2+ , CaAlSiN3: Eu, CaAlSi(ON)3: Eu. A phosphor showing the near-infrared region is 3Ga5O 12 : Cr.

[0021] As shown in FIGS. 12 to 13, the lighting device 10 according to an embodiment of the present disclosure includes the above-described first light-emitting device 1a, a second light-emitting device 1b, and a control unit 7. Hereinafter, it will be described with reference to the drawings. In the lighting device 10, the emission spectrum of the light emitted from the first light-emitting device 1a is defined as the first emission spectrum, and the emission spectrum of the light emitted from the second light-emitting device 1b is defined as the second emission spectrum. Further, the control unit 7 controls the first light-emitting device 1a and the second light-emitting device 1b. The emission spectrum of the light synthesized from the first emission spectrum and the second emission spectrum controlled by the control unit 7, that is, the emission spectrum of the light emitted from the lighting device 10 is defined as the third emission spectrum.

[0022] The control unit 7 controls the dimming rate for each light-emitting device. The dimming rate refers to the ratio of the voltage value and / or current value based on the power applied to each light-emitting device, that is, the rated current value and / or rated voltage value. In the case of a configuration using PWM control, it refers to the duty ratio of the voltage and / or current. As a result, the luminous flux output from each light-emitting device can be adjusted.

[0023] For example, the control unit 7 can adjust the light intensity emitted from the first light-emitting device 1a and / or the second light-emitting device 1b. Light intensity (light intensity) refers to the illuminance of light incident on the photosensitive surface, i.e., the incident light flux per unit area. The light intensity of each light-emitting device can be adjusted to any value between 0 and 1, with the maximum light intensity being 1. For example, by adjusting in increments of 0.1 or 0.01, the ratio of the light intensity emitted from each light-emitting device can be adjusted to produce light of various colors. Furthermore, if the first light-emitting device 1a and the second light-emitting device 1b have multiple light-emitting elements, as shown in Figure 13, the circuit of the light-emitting device 1 can be adjusted to determine which light-emitting element receives the voltage, and how much voltage or current is applied.

[0024] Furthermore, if the lighting device 10 has a first light-emitting device 1a and a second light-emitting device 1b having a second peak wavelength λ2, as shown in Figure 12, it is possible to adjust which light-emitting device is activated and which light-emitting device's emission intensity is increased. In other words, the third emission spectrum of the lighting device 10 is a combination of the first emission spectrum, which is the spectrum of light emitted from the first light-emitting device 1a, and the second emission spectrum, which is the spectrum of light emitted from the second light-emitting device 1b. The intensity of the first emission spectrum can be adjusted by adjusting the voltage or current applied to the first light-emitting device 1a, and the intensity of the second emission spectrum can be adjusted by adjusting the voltage or current applied to the second light-emitting device 1b. The emission spectrum of light emitted from the lighting device 10 under these controlled conditions is the third emission spectrum. At this time, the control unit 7 also adjusts which light-emitting device is selected.

[0025] More specifically, the control unit 7 can select the first light-emitting device 1a as the light-emitting device to be emitted, and can also control which of the multiple second light-emitting devices 1b to emit light based on the first emission spectrum. Furthermore, the control unit 7 can select a light-emitting device from among the first light-emitting device 1a and the multiple second light-emitting devices 1b to serve as a reference for controlling the dimming rate, and control the dimming rate of each light-emitting device based on the dimming rate of the reference light-emitting device. In this case, the control unit 7 may set a first dimming rate for the first light-emitting device 1a and control the dimming rates of the multiple second light-emitting devices 1b based on the first dimming rate. Alternatively, the control unit 7 may select a second light-emitting device 1b from among the multiple second light-emitting devices 1b that has a peak wavelength that results in the maximum light intensity in the wavelength range from a wavelength longer than the second peak wavelength λ2 to 750 nm, and set a second dimming rate for this second light-emitting device 1b. Then, based on the second dimming rate, it may control the dimming rates of the first light-emitting device 1a and the other multiple second light-emitting devices 1b.

[0026] Furthermore, the control unit 7 may control the first light-emitting device 1a and / or the second light-emitting device 1b based on signals and information received from an external source, such as wirelessly. The control unit 7 may also include a CPU or other arithmetic unit and memory.

[0027] The illumination device 10 according to the embodiment of this disclosure comprises a first light-emitting device 1a, a plurality of second light-emitting devices 1b, and a control unit 7. The first light-emitting device 1a has a first emission spectrum having a first peak wavelength λ1 in the wavelength region of 360 to 430 nm, and in which the light intensity continuously decreases in the range of 360 to 750 nm as it moves toward shorter and longer wavelengths, respectively, than the first peak wavelength. Continuously decreasing light intensity means that there is no maximum value in the emission spectrum in the decreasing interval of the wavelength region. In the measurement results of the emission spectrum, minute peaks and valleys that constitute measurement errors are not considered to identify the peak wavelength.

[0028] Each of the multiple second light-emitting devices 1b has a second peak wavelength λ2 in the wavelength region of 360 to 430 nm, and a third peak wavelength λ3 in the wavelength region up to 750 nm, with a second emission spectrum in which the light intensity decreases continuously as the wavelength moves toward wavelengths shorter than the second peak wavelength λ2 and longer than the third peak wavelength λ3, respectively. In this case, the illumination device 10 has multiple second light-emitting devices 1b. The third peak wavelength λ3 of each of the multiple second light-emitting devices 1b is preferably different wavelengths in the wavelength region of at least 430 nm to 750 nm.

[0029] As described above, the control unit 7 can select which light-emitting device to emit light from among the first light-emitting device 1a and the plurality of second light-emitting devices 1b. The control unit 7 can also control the dimming rate of each of the first light-emitting device 1a and the plurality of second light-emitting devices 1b. In other words, the control unit 7 can control the third emission spectrum of the lighting device 10 by controlling which light-emitting device emits light and at what brightness that device emits light. This makes it possible to control each light-emitting device having a spectrum with a different peak wavelength. Therefore, the third emission spectrum can be changed according to various applications.

[0030] Furthermore, the third peak wavelength λ3 of each of the multiple second light-emitting devices 1b are different wavelengths, and the full width at half maximum (FMAX) at each of the third peak wavelengths λ3 of the multiple second light-emitting devices 1b may increase as the wavelength increases. When reproducing visible light such as the solar spectrum, it is necessary to reproduce longer wavelength regions. For this reason, increasing the FMAX as the wavelength increases makes dimming easier. In this case, the third peak wavelengths λ3 of each of the multiple second light-emitting devices 1b may be separated by at least 10 nm or more. In an illumination device having emission spectra with different peak wavelengths, the smaller the wavelength region in which the respective emission spectra overlap, the wider the wavelength range over which the illumination can be emitted.

[0031] Furthermore, when the dimming rate of the first light-emitting device 1a is the same as the dimming rate of at least one second light-emitting device 1b, the light intensity at the second peak wavelength λ2 corresponding to this second light-emitting device 1b may be 25% or less of the light intensity at the first peak wavelength λ1. In other words, when the dimming rates of the first light-emitting device 1a and the second light-emitting device 1b are the same, the light intensity in the 360-430 nm range may be highest for the first light-emitting device 1a. In this case, if the peak wavelengths of the excitation light from multiple second light-emitting devices 1b (second peak wavelength λ2) overlap with the first peak wavelength λ1, the influence of the second peak wavelength λ2 can be reduced. This makes it easier to dim light in the violet region corresponding to 360-430 nm.

[0032] Furthermore, the third emission spectrum may have peak wavelengths at the positions of the first peak wavelength λ1, the second peak wavelength λ2, and multiple third peak wavelengths λ3. Since the emission spectrum of the lighting device 10 is the emission spectrum of the combined light emitted from the first light-emitting device 1a and multiple second light-emitting devices 1b, the magnitude of the light intensity changes depending on the dimming rate of each light-emitting device. In this case, the further apart the third peak wavelengths λ3 of the multiple second light-emitting devices 1b are, the smaller the overlap of the light at each peak wavelength and the more independent the peak positions are. When this configuration is satisfied, the third emission spectrum of the light emitted as the lighting device 10 has a peak wavelength at the same wavelength as the third peak wavelength λ3 in each of the multiple second light-emitting devices 1b. Here, small overlap means that when the two target third peak wavelengths λ3 overlap, if the light intensity at the overlapping boundary wavelength is less than 50% of the light intensity at the higher of the target third peak wavelengths λ3, then the peak of the third emission spectrum is located at the same wavelength as the third peak wavelength λ3 of the second light-emitting device 1b. By selecting multiple second light-emitting devices 1b in this manner in the control unit 7, the illumination device 10 can easily adjust the reproduction of light having the peak wavelength of the third emission spectrum at the peak wavelength of each light-emitting device.

[0033] Conversely, the third emission spectrum may have a peak wavelength in the wavelength region between two third peak wavelengths λ3, in addition to the first peak wavelength λ1 and the second peak wavelength λ2. This is because the closer the third peak wavelengths λ3 of the multiple second light-emitting devices 1b are to each other, the greater the overlap of light around each third peak wavelength λ3. Therefore, the third emission spectrum has a peak at the wavelength with the greatest overlap of light. In this case, the second emission spectra are overlapping. Here, overlapping means that when the two target third peak wavelengths λ3 overlap, if the light intensity at the overlapping boundary wavelength is 50% or more of the light intensity at the higher of the target third peak wavelengths λ3, then the peak of the third emission spectrum is located at a wavelength between the third peak wavelengths λ3 of the multiple target second light-emitting devices 1b. By selecting multiple second light-emitting devices 1b in this way in the control unit 7, the illumination device 10 can easily adjust the reproduction of light having a peak wavelength of the third emission spectrum in addition to the peak wavelength of each light-emitting device.

[0034] Furthermore, the first peak wavelength λ1 and the second peak wavelength λ2 may be the same or different. In addition, the second peak wavelength λ2 of each of the multiple second light-emitting devices 1b, i.e., the wavelength of the excitation light, may be the same or different. Note that the same peak wavelength means that the difference in peak wavelengths is less than 2 nm. This means that the wavelength error of light-emitting devices with the same peak wavelength setting is less than 2 nm. When the first peak wavelength λ1 and the second peak wavelength λ2 are the same peak wavelength, the color unevenness and color variation of the light emitted from the illumination device can be reduced because their respective peak wavelengths are the same. In this case, the full width at half maximum (FWHM) of each of the multiple second light-emitting devices 1b at the second peak wavelength λ2 may be the same. When the FWHM of each second peak wavelength λ2 is the same, color unevenness in the excitation light wavelength range can be reduced.

[0035] Figure 4 shows an example where the lighting device 10 has a first light-emitting device 1a and seven types of second light-emitting devices 1b, and displays the emission spectra of each when the dimming rate is 100%. For example, the first light-emitting device 1a emits light having a first peak wavelength in the wavelength range of 360 to 430 nm. The second light-emitting device 1b has a light-emitting element that emits a second peak wavelength in the 360 ​​to 430 nm range, and when this is used as excitation light to irradiate a phosphor, it further emits light having a third peak wavelength. For example, among the second light-emitting devices 1b, the one having a third peak wavelength λ3 in the wavelength region from the second peak wavelength λ2 to 480 nm is designated as the second light-emitting device A, the one having a third peak wavelength λ3 in the wavelength region of 440 to 520 nm is designated as the second light-emitting device B, the one having a third peak wavelength λ3 in the wavelength region of 480 to 570 nm is designated as the second light-emitting device C, the one having a third peak wavelength λ3 in the wavelength region of 520 to 620 nm is designated as the second light-emitting device D, the one having a third peak wavelength λ3 in the wavelength region of 550 to 650 nm is designated as the second light-emitting device E, the one having a third peak wavelength λ3 in the wavelength region of 580 to 690 nm is designated as the second light-emitting device F, and the one having a third peak wavelength λ3 in the wavelength region of 620 to 730 nm is designated as the second light-emitting device G.

[0036] Figure 5 shows that when the dimming rate of the first light-emitting device 1a is 2%, the dimming rate of the second light-emitting device A is 10%, the dimming rate of the second light-emitting device B is 25%, the dimming rate of the second light-emitting device C is 30%, the dimming rate of the second light-emitting device D is 20%, the dimming rate of the second light-emitting device E is 10%, the dimming rate of the second light-emitting device F is 25%, and the dimming rate of the second light-emitting device G is 20%, a spectrum close to D50, which is the standard spectrum of sunlight during the day, can be obtained. Furthermore, when the dimming rate of the first light-emitting device 1a is 2%, the dimming rate of the second light-emitting device A is 80%, the dimming rate of the second light-emitting device B is 40%, the dimming rate of the second light-emitting device C is 20%, the dimming rate of the second light-emitting device D is 5%, the dimming rate of the second light-emitting device E is 5%, the dimming rate of the second light-emitting device F is 0% (off), and the dimming rate of the second light-emitting device G is 0% (off), a spectrum close to blue can be produced, which can also be made to approximate the spectrum of sunlight in water.

[0037] In this configuration, various colors of light can be emitted by controlling the dimming rate of multiple second light-emitting devices 1b.

[0038] Furthermore, the light-emitting device 1 according to the embodiment of this disclosure can emit highly color-rendering light that approximates the spectrum of sunlight by adjusting the dimming rate of each light-emitting device. That is, the difference between the light intensity in the spectrum of sunlight and the light intensity in the third emission spectrum of the lighting device 10 according to the embodiment of this disclosure can be reduced, and a lighting device 10 that can emit light approximating the spectrum of sunlight can be manufactured.

[0039] The lighting device 10 of the embodiments of this disclosure is used for lighting indoors, such as inside a building or house. For example, it may consist of a single set of a first light-emitting device 1a and a plurality of second light-emitting devices 1b, or it may be configured with a plurality of such devices arranged in a row. For example, if it is a lighting device for a living space, it can create a lighting environment that is similar to sunlight, even indoors. Also, if it is used as a lighting device for inspecting the appearance of painted items, such as passenger cars, it can create an inspection environment that is similar to sunlight, even indoors. By irradiating light that is close to the spectrum of sunlight even indoors, it is possible to make the colors appear closer to what is seen under sunlight (improved color rendering), and when performing color inspections, inspections can be performed more accurately and in a state closer to the actual usage environment.

[0040] Furthermore, as part of controlling the lighting to approximate the sunlight described in this disclosure, the lighting may be controlled to continuously change the sunlight from morning to evening. By continuously changing the sunlight from morning to evening, it is possible to synchronize with the human body's internal rhythm. In this case, for example, to reproduce morning, the dimming rate of the blue light can be increased to emit high color temperature light. To reproduce evening, the dimming rate of the red light can be increased to emit low color temperature light. At this time, the dimming rate can also be adjusted so that the average color rendering index Ra is 85 or higher.

[0041] Furthermore, as shown in Figures 6 to 8, the illumination device 10 and light-emitting device 1 in this disclosure can reproduce the light of a Japanese candle (color temperature: 1800 to 2100K) as low color temperature light. Specifically, one of the multiple second light-emitting devices 1b may have a peak wavelength in the wavelength range of 610 to 730 nm. In this case, only the second light-emitting device 1b under these conditions should be made to emit light by the control unit 7. In this case, the emission spectrum of the second light-emitting device 1b may have a relative light intensity of 0.05 to 0.3 at the peak wavelength and a relative light intensity of 0.1 or less at 440 nm to 480 nm.

[0042] Furthermore, by adjusting the light emission intensity of multiple second light-emitting devices 1b with the control unit 7, light that reproduces that of a Japanese candle having a peak wavelength A in the 610-730 nm wavelength range under the following conditions may be emitted. These conditions are that the relative light intensity at the second peak wavelength is 0.05-0.3, the relative light intensity at 440 nm-480 nm is 0.1 or less, and the light intensity in the wavelength range from 480 nm to the peak wavelength A increases continuously. In this case, the dimming ratio may be set low for second light-emitting devices B-E, for example, to less than 20%, and high for second light-emitting devices F and G, for example, to 50% or more.

[0043] <Lighting and illumination devices for recreating traditional Japanese candles> As described above, the lighting device 10 may include a light-emitting device 1 that reproduces the light of a Japanese candle among a plurality of light-emitting devices 1, or it may reproduce the light of a Japanese candle by controlling the dimming rate of the plurality of light-emitting devices 1. Furthermore, the emission spectra shown in Figures 6 to 8 are not those of the lighting device 10, but are possessed by the light-emitting devices 1 themselves, and the light emitted from the light-emitting devices 1 can also reproduce the light of a Japanese candle.

[0044] When the light-emitting device 1 itself reproduces the light of a Japanese candle, the light-emitting device 1 has a light-emitting element 3 and a wavelength conversion member 6. Furthermore, the emission spectrum of the light emitted from the lighting device 10 or the light-emitting device 1 emits light that is specified by an emission spectrum having an emission peak wavelength in the wavelength region of 610 nm to 730 nm and an excitation peak wavelength in the wavelength region of 360 nm to 430 nm. Also, when the light intensity at the emission peak wavelength is set to 1, the relative light intensity at the excitation peak wavelength is 0.05 to 0.3, and the relative light intensity in the 440 nm to 480 nm range is 0.1 or less. Furthermore, the light intensity in the wavelength region from 480 nm to the emission peak wavelength increases continuously.

[0045] The wavelength conversion member 6 may comprise a plurality of phosphors 60. The phosphors 60 convert light having a peak wavelength (excitation peak wavelength λe) in the 360 ​​nm to 430 nm wavelength range into light having a peak wavelength (emission peak wavelength λL) in the 610 nm to 730 nm wavelength range. The wavelength conversion member 6 is positioned to convert the light emitted by the light-emitting element 3 into light having a peak wavelength in the 610 nm to 730 nm wavelength range. Note that the 610 nm to 730 nm wavelength range is included in the visible light region.

[0046] The phosphor 60 may include a phosphor having a peak wavelength in the 600 nm to 660 nm wavelength range. Examples of phosphors having a peak wavelength in the 600 nm to 660 nm wavelength range include phosphors that exhibit red color. Examples of red-colored phosphors include Y2O2S:Eu, Y2O3:Eu, and SrCaClAlSiN3:Eu. 2+ CaAlSiN3:Eu, or CaAlSi(ON)3:Eu can be used. The red phosphor converts light incident on the wavelength conversion member 6 into light having a peak wavelength in the 600nm to 660nm wavelength range and emits the converted light. In addition to the red phosphor described above, the wavelength conversion member 6 may also contain, for example, a phosphor that exhibits a color in the near-infrared region and has a peak wavelength in the 680nm to 800nm ​​wavelength range. Examples of phosphors exhibiting a color in the near-infrared region include 3Ga5O 12Examples include Cr. By selecting one of these phosphors, or by combining several of them, a phosphor 60 having an emission peak wavelength λL in the range of 610 nm to 730 nm can be obtained.

[0047] This disclosure does not require the inclusion of phosphors of other colors. By not including phosphors of other colors, it is possible to reproduce red light with an emission peak wavelength λL in the 610nm to 730nm range. In particular, in this disclosure, in addition to not including phosphors of other colors, the relative light intensity in the blue wavelength region described later is small (0.1 or less), so the reproduction rate of red light with an emission peak wavelength λL in the 610nm to 730nm range can be improved compared to when using a blue-emitting LED. Note that other phosphors as described above may be included in trace amounts to the extent that they do not affect the emission peak wavelength λL. By including trace amounts of phosphors other than red, it is possible to make the color closer to a natural color.

[0048] The peak wavelengths mentioned above and those described later refer to the wavelength at which the spectrum shows a maximum value, that is, the wavelength at the peak within the spectrum's cycle of valleys and peaks. However, when a phosphor emits various colors, the spectrum may have minute peaks and valleys. Such minute peaks and valleys are not used when determining the peak wavelength. In other words, for example, a maximum value where the width from valley to valley is 20 nm or less may not be considered a peak.

[0049] <Emission spectrum of lighting and light-emitting devices for recreating Japanese candles> As described above, the emission spectra of the illumination device 10 and light-emitting device 1 of this disclosure have an excitation peak wavelength λe in the wavelength region of 360 nm to 430 nm and an emission peak wavelength λL in the wavelength region of 610 nm to 730 nm. In this case, when the light intensity at the emission peak wavelength λL is set to 1, it is preferable that the relative light intensity at the excitation peak wavelength λe is 0.05 to 0.3, and the relative light intensity in the 440 nm to 480 nm region is 0.1 or less. Furthermore, it is preferable that the light intensity in the wavelength region from 480 nm to the emission peak wavelength λL increases continuously. The excitation peak wavelength λe is the excitation light of the light-emitting device 3. If the relative light intensity of the excitation light is 0.05 to 0.3, even if direct purple light is emitted to the outside as stray light, it will have little effect on the color of the light to be emitted. In addition, the emission intensity can be sufficiently maintained. Furthermore, because the relative light intensity in the 440nm to 480nm range is 0.1 or less, it contains almost no blue light as perceived by humans, thus minimizing the impact on the color of the emitted light and improving the reproduction rate of the desired light. In addition, because the light intensity in the wavelength range from 480nm to the emission peak wavelength λL increases continuously, there is no peak wavelength in this wavelength range, allowing for the favorable reproduction of colors near the emission peak wavelength λL.

[0050] Here, the continuous increase in light intensity in the wavelength range from 480 nm to the emission peak wavelength λL means, for example, that the spectrum does not have a maximum value in the wavelength range from 480 nm to the emission peak wavelength λL. As mentioned above, the spectrum may have small peaks and troughs, but such small peaks and troughs do not need to be used when identifying the maximum value in this context.

[0051] The emission spectra of the lighting device 10 and light-emitting device 1 according to the first to third embodiments of this disclosure will be described in detail with reference to Figures 6 to 8. Note that the lighting device 10 and the light-emitting device 1 according to the first to third embodiments differ in the materials and quantities constituting the phosphor 60. The emission spectrum is measured using spectroscopy, for example, by a spectrophotometer. The lighting device 10 and light-emitting device 1 according to the first to third embodiments are devices that emit light that mimics the color of candlelight. Therefore, Figures 6 to 8 show a comparison between the measured values ​​of candlelight and the measured values ​​of each embodiment. More specifically, candle (1) shows the measured value when the candlelight is bright and flickering, candle (2) shows the measured value when the candlelight is quiet and stable, and candle (3) shows the measured value when the candlelight is dim and flickering. Furthermore, each embodiment shows (1) a reproduction of light when it is bright and fluctuating, (2) a reproduction of light when it is quiet and stable, and (3) a reproduction of light when it is dim and fluctuating.Hereafter, the emission peak wavelength λL in each embodiment will be λL1 in the first embodiment, λL2 in the second embodiment, and λL3 in the third embodiment.

[0052] (First Embodiment) As shown in Figure 6, the emission spectrum of the first embodiment has an emission peak wavelength λL1 in the wavelength region of 610 nm to 650 nm. Note that in Figure 6, the emission peak wavelength λL1 is located around 630 nm. The emission peak wavelength λL1 corresponds to the wavelength of light emitted by the phosphor 60. When the emission peak wavelength λL1 is located in the wavelength region of 610 nm to 650 nm, the phosphor 60 mainly contains the red phosphor 60 described above. In this embodiment, the relative light intensity at the second peak wavelength λ2 is approximately 0.26, and the relative light intensity in the 440 nm to 480 nm range is 0.1 or less. As a result, it contains almost no blue light as perceived by humans, thus reducing the influence on the color of the emitted light and improving the reproduction rate of the desired light. Furthermore, the light intensity in the wavelength region from 480 nm to the emission peak wavelength λL1 (around 630 nm) increases continuously, and there is no peak wavelength in this range. Therefore, it is possible to reproduce colors near the emission peak wavelength λL1, that is, colors in the range of 610 nm to 650 nm. The illumination device 10 and light-emitting device 1 according to the first embodiment can achieve brighter light with a more pronounced red color compared to other embodiments.

[0053] (Second Embodiment) As shown in Figure 7, the emission spectrum of the second embodiment has an emission peak wavelength λL2 in the wavelength region of 620 nm to 670 nm. Note that in Figure 7, the emission peak wavelength λL2 is located around 645 nm. The emission peak wavelength λL2 corresponds to the wavelength of light emitted by the phosphor 60. When the emission peak wavelength λL2 is located in the wavelength region of 620 nm to 670 nm, the phosphor 60 mainly contains the red phosphor 60 described above. In this embodiment, the relative light intensity at the second peak wavelength λL2 is approximately 0.25, and the relative light intensity in the 440 nm to 480 nm range is 0.09 or less. As a result, it contains almost no blue light as perceived by humans, thus reducing the influence on the color of the emitted light and improving the reproduction rate of the desired light. Furthermore, the light intensity in the wavelength region from 480 nm to the emission peak wavelength λL2 (around 645 nm) increases continuously, and there is no peak wavelength in this range. Therefore, it is possible to reproduce colors near the emission peak wavelength λL2, that is, 620nm to 670nm. In particular, the lighting device 10 and light-emitting device 1 according to the second embodiment can be made to have a good balance of brightness and a color temperature close to that of candlelight.

[0054] (Third embodiment) As shown in Figure 8, the emission spectrum of the third embodiment has an emission peak wavelength λL3 in the wavelength region of 690 nm to 730 nm. Note that in Figure 8, the emission peak wavelength λL3 is located around 715 nm. The emission peak wavelength λL3 corresponds to the wavelength of light emitted by the phosphor 60. When the emission peak wavelength λL3 is located in the wavelength region of 690 nm to 730 nm, the phosphor 60 mainly contains phosphors 60 with the colors in the near-infrared region as described above. In this embodiment, the relative light intensity at the second peak wavelength λ2 is approximately 0.06, and the relative light intensity at 440 nm to 480 nm is 0.08 or less. As a result, it contains almost no blue light as perceived by humans, thus reducing the influence on the color of the emitted light and improving the reproduction rate of the desired light. Furthermore, the light intensity in the wavelength region from 480 nm to the emission peak wavelength λL3 (around 715 nm) increases continuously, and there is no peak wavelength in this range. Therefore, it is possible to reproduce colors near the emission peak wavelength λL3, that is, colors in the range of 690nm to 730nm. The illumination device 10 and the light-emitting device 1 according to the third embodiment can realize light that is in line with the measured values ​​of candle light, that is, light with a high reproducibility, as shown in Figure 8.

[0055] As described above, the emission spectrum of the light emitted by the illumination device 10 and light-emitting device 1 of this disclosure contains almost no blue light that humans perceive, thus minimizing the influence of blue light on the color of the emitted light. Furthermore, it is possible to improve the reproduction rate of the desired light color (red). In particular, when the objective is to reproduce the light of a candle with a color temperature of 2000K, the light-emitting device 1 of the second embodiment can reproduce light that is closer to candle light in terms of the balance between brightness and color temperature reproduction rate.

[0056] <Color rendering properties of lighting and light-emitting devices> The color rendering properties of the lighting device 10 and light-emitting device 1 related to this disclosure will be described below.

[0057] "Color rendering index" is one of the indicators used to evaluate the quality of a light source. It quantifies how colors appear using natural light as a reference, and the color rendering index is expressed as a color rendering score. The color rendering score can be expressed as the average color rendering score Ra, special color rendering scores R9, R10, R11, R12, R13, R14, R15, etc. For example, light sources with an average color rendering score Ra=100 are the sun and an incandescent light bulb.

[0058] The lighting device 10 and light-emitting device 1 according to this disclosure can realize a light-emitting device 1 with excellent color rendering, having an average color rendering index Ra of 85 or higher. For example, the lighting device 10 and light-emitting device 1 of the first embodiment have an average color rendering index Ra of 88.0, the lighting device 10 and light-emitting device 1 of the second embodiment have an average color rendering index Ra of 88.1, and the lighting device 10 and light-emitting device 1 of the third embodiment have an average color rendering index Ra of 88.4.

[0059] <Color temperature of lighting and light-emitting devices> Color temperature is a numerical representation of the color of light emitted by a light source, and is expressed in units of K (Kelvin). A low color temperature means that the light emitted by the light source is reddish in color. A high color temperature means that the light emitted by the light source is bluish in color. For example, the color temperature of light emitted by an incandescent light bulb is approximately 2800K. For example, the color temperature of daylight white light is approximately 4200K.

[0060] The light identified by the emission spectrum of the illumination device 10 and light-emitting device 1 according to the first embodiment has a color temperature of 2083K. The light identified by the emission spectrum of the illumination device 10 and light-emitting device 1 according to the second embodiment has a color temperature of 1964K. The light identified by the emission spectrum of the illumination device 10 and light-emitting device 1 according to the third embodiment has a color temperature of 1825K.

[0061] The emission spectra of the lighting device 10 and light-emitting device 1 according to the first to third embodiments show a range of approximately 2000K, from 1800K to 2100K, including measurement variations, and can reproduce a warm red color similar to that of a Japanese candle.

[0062] Furthermore, a lighting device 10 equipped with at least one light-emitting device 1 that reproduces the light of a Japanese candle may also be equipped with a control unit 7 that adjusts the intensity (dimming rate) of the light from the light-emitting device 1, similar to the configuration described above. The control unit 7 can adjust the intensity of the light emitted from the light-emitting device 1 by controlling the current value flowing through the light-emitting device 1. The control unit 7 can also adjust the light emitted from the light-emitting device 1 to appear fluctuating by changing the dimming rate over time or by randomly changing the dimming rate. The control unit 7 may be attached together with the wiring board 12, or the lighting device 10 may be equipped with a receiving unit that sends commands to the part that controls the current on the wiring board 12, etc., via wireless communication from an external source.

[0063] In this way, because the lighting device 10 has a control unit 7 that can control dimming, it is possible to reproduce light with varying intensity (brightness and darkness) even with light of the same color temperature.

[0064] <Examples of lighting device usage> The lighting device 10 disclosed herein can reproduce the light of a candle (Japanese candle). For example, the lighting device 10 can be used to illuminate pillars, Japanese paintings, walls, etc., in temples, allowing users to experience the colors seen under candlelight. Furthermore, by adjusting the intensity of the light, it is possible to reproduce the flickering of a candle flame.

[0065] Furthermore, the lighting device 10 may be used not only indoors, such as inside a building or house, but also outdoors.

[0066] <Lighting system configuration> As shown in Figures 9 to 11, the lighting device 10 comprises a long housing 11 with an opening at the top, multiple light-emitting devices 1 arranged in a line along the longitudinal direction inside the housing 11, a long wiring board 12 on which the multiple light-emitting devices 1 are mounted, and a long translucent substrate 13 supported by the housing 11 and closing the opening of the housing 11.

[0067] The housing 11 has the function of holding the translucent substrate 13 and the function of dissipating the heat emitted by the light-emitting device 1 to the outside. The housing 11 is made of a metal such as aluminum, copper or stainless steel, plastic or resin, for example. The housing 11 has a bottom portion 21a that extends in the longitudinal direction, and is erected from both ends of the bottom portion 21a in the width direction. Furthermore, it has a pair of support portions 21b that extend in the longitudinal direction, and consists of a long main body portion 21 that is open on the top and both sides in the longitudinal direction, and two lid portions 22 that close the openings on one and the other side in the longitudinal direction of the main body portion 21, respectively. The upper part of each support portion 21b on the inside of the housing 11 is provided with a holding portion formed so that recesses for holding the translucent substrate 13 are facing each other along the longitudinal direction. The length of the housing 11 in the longitudinal direction is set to, for example, 100 mm or more and 2000 mm or less.

[0068] The wiring board 12 is fixed to the bottom surface inside the housing 11. The wiring board 12 is a printed circuit board such as a rigid board, a flexible board, or a rigid-flexible board. The wiring pattern of the wiring board 12 and the wiring pattern of the substrate 2 in the light-emitting device 1 are electrically connected via solder or conductive adhesive. A signal from the wiring board 12 is transmitted to the light-emitting element 3 via the substrate 2, causing the light-emitting element 3 to emit light. Power is supplied to the wiring board 12 via wiring from an external power supply.

[0069] The translucent substrate 13 is made of a material that transmits light emitted from the light-emitting device 1, and is composed of a light-transmitting material such as acrylic resin or glass. The translucent substrate 13 is a rectangular plate, and its length in the longitudinal direction is set to, for example, 98 mm or more and 1998 mm or less. The translucent substrate 13 is inserted into the recesses formed in each of the support parts 21b described above through an opening on one or the other side in the longitudinal direction of the main body 21. Thereafter, by sliding it along the longitudinal direction, it is supported by a pair of support parts 21b at a position away from the multiple light-emitting devices 1. The lighting device 10 is then constructed by closing the openings on one and the other side in the longitudinal direction of the main body 21 with the cover part 22.

[0070] The above-described lighting device 10 is a linear lighting device in which multiple light-emitting devices 1 are arranged in a straight line, but it is not limited to this and may also be a surface lighting device in which multiple light-emitting devices 1 are arranged in a matrix or staggered grid pattern.

[0071] In the embodiments of the present disclosure, each of the second light-emitting devices 1b of the lighting device 10 includes, as described above, one or more of the five types of phosphors consisting of a phosphor that emits blue fluorescence, a phosphor that emits blue-green fluorescence, a phosphor that emits green fluorescence, a phosphor that emits red fluorescence, and a phosphor that emits fluorescence in the near-infrared region as a phosphor contained in one wavelength conversion member 6. However, the invention is not limited to this, and two types of wavelength conversion members may be provided. When two types of wavelength conversion members are provided, the first wavelength conversion member may contain different phosphors dispersed in it, or phosphors dispersed in different combinations in it, and the second wavelength conversion member may contain different phosphors dispersed in it. Furthermore, these two wavelength conversion members may be provided in one light-emitting device, and the light emitted after passing through each wavelength conversion member may be mixed. In this way, the color rendering of the emitted light can be easily controlled.

[0072] This disclosure is not limited to the examples of the embodiments described above, and various modifications, such as numerical values, are possible. The various combinations of feature parts in this embodiment are not limited to the examples of the embodiments described above. [Explanation of symbols]

[0073] 1. Light-emitting device 1a First light-emitting device 1b Second light-emitting device 10 Lighting devices 11 cabinets 12 Wiring board 13 Translucent substrate 2 circuit boards 21 Main body 21a bottom 21b Support part 22 Lid 3 Light-emitting elements 4 Frame 5 Sealing member 6 Wavelength conversion component 60 Phosphors 7 Control Unit λ1 First peak wavelength λ2 Second peak wavelength λ3 Third peak wavelength λe excitation peak wavelength λL emission peak wavelength

Claims

1. A first light-emitting device comprising a first excitation light source and a first phosphor, which emits light having a first peak wavelength, A second light-emitting device that emits light having a second peak wavelength that is longer than the first peak wavelength, A third light-emitting device that emits light having a third peak wavelength in the wavelength region of 610 nm to 730 nm, which is longer wavelength than the second peak wavelength, The system comprises a control unit that controls the first light-emitting device, the second light-emitting device, and the third light-emitting device, A lighting device in which the full width at half maximum of the third peak wavelength is greater than the full width at half maximum of the second peak wavelength.

2. A first light-emitting device comprising a first excitation light source and a first phosphor, which emits light having a first peak wavelength, A second light-emitting device that emits light having a second peak wavelength that is longer than the first peak wavelength, A third light-emitting device that emits light having a third peak wavelength in the wavelength region of 610 nm to 730 nm, which is longer wavelength than the second peak wavelength, A fourth light-emitting device having a fourth emission spectrum that includes a fourth peak wavelength on a shorter wavelength side than the first light-emitting device, A lighting device comprising a control unit for controlling the first light-emitting device, the second light-emitting device, the third light-emitting device, and the fourth light-emitting device.

3. The lighting device according to claim 2, wherein when the dimming rate of the fourth light-emitting device is the same as the dimming rate of at least one of the first light-emitting device, the second light-emitting device, or the third light-emitting device, the light intensity at the first peak wavelength of the first light-emitting device, the light intensity at the second peak wavelength of the second light-emitting device, or the light intensity at the third peak wavelength of the third light-emitting device, controlled at the same dimming rate as the dimming rate of the fourth light-emitting device, is 25% or less of the light intensity at the peak wavelength of the fourth light-emitting device.

4. A first light-emitting device comprising a first excitation light source and a first phosphor, which emits light having a first peak wavelength, A second light-emitting device that emits light having a second peak wavelength that is longer than the first peak wavelength, A third light-emitting device that emits light having a third peak wavelength in the wavelength region of 610 nm to 730 nm, which is longer wavelength than the second peak wavelength, The system comprises a control unit that controls the first light-emitting device, the second light-emitting device, and the third light-emitting device, The control unit selects a light-emitting device from among the first light-emitting device, the second light-emitting device, and the third light-emitting device to be used as a reference for controlling the dimming rate, and controls the dimming rate of each light-emitting device based on the dimming rate of the reference light-emitting device.

5. A first light-emitting device comprising a first excitation light source and a first phosphor, which emits light having a first peak wavelength, A second light-emitting device that emits light having a second peak wavelength that is longer than the first peak wavelength, A third light-emitting device that emits light having a third peak wavelength in the wavelength region of 610 nm to 730 nm, which is longer wavelength than the second peak wavelength, The system comprises a control unit that controls the first light-emitting device, the second light-emitting device, and the third light-emitting device, The control unit sets the dimming rate of the third light-emitting device and controls the dimming rates of the first light-emitting device and the second light-emitting device based on the dimming rate of the third light-emitting device, in a lighting device.

6. A first light-emitting device comprising a first excitation light source and a first phosphor, which emits light having a first peak wavelength, A second light-emitting device that emits light having a second peak wavelength that is longer than the first peak wavelength, A third light-emitting device that emits light having a third peak wavelength in the wavelength region of 610 nm to 730 nm, which is longer wavelength than the second peak wavelength, The system comprises a control unit that controls the first light-emitting device, the second light-emitting device, and the third light-emitting device, A lighting device in which the full width at half maximum (FWHM) of the first peak wavelength, the FWHM of the second peak wavelength, and the FWHM of the third peak wavelength are the same.

7. A first light-emitting device comprising a first excitation light source and a first phosphor, which emits light having a first peak wavelength, A second light-emitting device that emits light having a second peak wavelength that is longer than the first peak wavelength, A third light-emitting device that emits light having a third peak wavelength in the wavelength region of 610 nm to 730 nm, which is longer wavelength than the second peak wavelength, The system comprises a control unit that controls the first light-emitting device, the second light-emitting device, and the third light-emitting device, A lighting device in which the full width at half maximum (FWHM) of the third peak wavelength is greater than the FWHM of the second peak wavelength, and the FWHM of the second peak wavelength is greater than the FWHM of the first peak wavelength.

8. The first light-emitting device emits light having the first peak wavelength in the wavelength range of 440 to 520 nm. The illumination device according to any one of claims 1 to 7, wherein the second light-emitting device emits light having the second peak wavelength in the wavelength region of 480 to 570 nm.

9. The second light-emitting device includes a second excitation light source and a second phosphor that emits light at a longer wavelength than the first phosphor. The illumination apparatus according to any one of claims 1 to 8, wherein the third light-emitting device includes a third excitation light source and a third phosphor that emits light at a longer wavelength than the second phosphor.

10. The first phosphor emits light having the first peak wavelength in the wavelength range of 440 to 520 nm. The second phosphor emits light having the second peak wavelength in the wavelength range of 480 to 570 nm. The lighting device according to claim 9, wherein the third phosphor emits light having the third peak wavelength in the wavelength region of 610 to 730 nm.

11. The illumination device according to any one of claims 1 to 10, wherein the emission spectrum of the illumination device has an emission peak wavelength in the wavelength region of 610 nm to 730 nm, and the light intensity in the wavelength region from 480 nm to the emission peak wavelength increases continuously.

12. The lighting device according to any one of claims 1 to 11, wherein the control unit selects from the first light-emitting device, the second light-emitting device, and the third light-emitting device to emit light.

13. The lighting device according to any one of claims 1 to 12, wherein the control unit controls the dimming rate of each of the first light-emitting device, the second light-emitting device, and the third light-emitting device.

14. The illumination device according to any one of claims 1 to 13, wherein the first peak wavelength, the second peak wavelength, and the third peak wavelength are separated from each other by at least 10 nm.

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