JP2013161889A - Light-emitting device, vehicular headlamp, and color adjusting method of light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust the color of illumination light while suppressing the generation of color unevenness.SOLUTION: A headlamp 1a related to one embodiment of this invention includes: a semiconductor laser element 2; and a light-emitting portion 5 including at least a first fluorescent body and a second fluorescent. The semiconductor laser element 2 changes the wavelength of a laser beam in a wavelength area in which an absorption wavelength area of the first fluorescent body and an absorption wavelength area of the second fluorescent area are superimposed with each other.

Description

  The present invention relates to a light emitting device that uses fluorescence generated by irradiating a fluorescent material with excitation light as illumination light, a vehicle headlamp, and a color adjustment method for the light emitting device.

  2. Description of the Related Art In recent years, semiconductor light emitting devices such as light emitting diodes (LEDs) and semiconductor laser devices (LDs) are provided as excitation light sources, and excitation light generated from these excitation light sources is emitted to a light emitting unit including a phosphor. Research on an illuminating device using fluorescence generated by irradiation as illumination light has been actively performed.

  As a technique related to such an illumination device, for example, Patent Document 1 includes a yellow LED 10 having a low color temperature and a blue LED 11 having a high color temperature, as shown in FIG. An illumination device 12 that adjusts the color of illumination light by mixing emitted yellow light and blue light is disclosed.

JP 2010-272536 A (published on December 02, 2010)

Naoto Kijima, “All about White LED Lighting Technology”, Industrial Research Committee, 2009, Chapter 3, Tsunemasa Taguchi Ichiro Nakanishi, “Phosphors for White LED Applications”, Japan Society of Applied Physics, 2011, Applied Physics Vol. 80, No. 4

  However, since the illumination device 12 disclosed in Patent Document 1 is configured to adjust the color of illumination light by mixing light of different colors emitted from a plurality of LEDs (light emitting units), the resulting illumination is obtained. Color unevenness occurs in light. Therefore, in the illumination device 12 disclosed in Patent Document 1, a diffusion plate or the like is necessary to prevent this color unevenness.

  Further, in the lighting device 12 disclosed in Patent Document 1, as shown in FIG. 14B, a circuit for changing the current value of the blue LED 11 is necessary, and there is a problem that the device configuration becomes complicated. is there.

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to make it possible to adjust the color of illumination light while suppressing the occurrence of color unevenness with a more simplified apparatus configuration. Is to realize a simple light emitting device. Another object of the present invention is to realize a color adjustment method for a light emitting device capable of adjusting the color of illumination light while suppressing the occurrence of color unevenness.

  In order to solve the above problems, a light emitting device according to the present invention includes an excitation light source that emits excitation light, a first phosphor that emits fluorescence by absorbing the excitation light emitted from the excitation light source, and A light emitting unit including at least a second phosphor that emits fluorescence having a peak wavelength different from that of the first phosphor, and the excitation light source includes an absorption wavelength region of the first phosphor and the second phosphor. The wavelength of the excitation light is changed in a wavelength region where the absorption wavelength regions of the phosphors overlap each other.

  In the above configuration, the light emitting unit includes at least a first phosphor and a second phosphor that emits fluorescence having a peak wavelength different from that of the first phosphor, and the excitation light source is the first phosphor. The wavelength of the excitation light is changed in a wavelength region where the absorption wavelength region and the absorption wavelength region of the second phosphor overlap each other.

  Here, the luminous efficiency of the phosphor changes for each type of phosphor according to the wavelength of the excitation light irradiated. For this reason, the absorption wavelength region of the first phosphor and the absorption wavelength region of the second phosphor overlap each other with respect to the wavelength of the excitation light applied to the light emitting unit including at least the first phosphor and the second phosphor. By changing in the wavelength region, the ratio of the fluorescence emitted from the first phosphor and the fluorescence emitted from the second phosphor changes, so that the color of the illumination light emitted from the light emitting unit is adjusted. Can do.

  As described above, according to the above configuration, the color of the illumination light emitted from a single light emitting unit can be adjusted by controlling the wavelength of the excitation light. Compared with a configuration in which the light emitted from the light emitting unit is mixed to adjust the color of the illumination light, the device configuration can be simplified and the occurrence of color unevenness can be suppressed.

  Therefore, according to said structure, the light-emitting device which can adjust the color of illumination light can be implement | achieved with the more simplified apparatus structure, suppressing generation | occurrence | production of a color nonuniformity.

  Moreover, in the light emitting device according to the present invention, the excitation light source includes the absorption edge of the first phosphor or the absorption edge of the second phosphor and the wavelength near the absorption edge in the overlapping wavelength region. In the region, it is preferable to change the wavelength of the excitation light.

  In general, when a phosphor is excited in the wavelength region of the absorption edge, the luminous efficiency of the phosphor changes greatly.

  According to the above configuration, the excitation light source has the wavelength of the excitation light in the wavelength region of the first fluorescent material or the second fluorescent material, and in the wavelength region in the vicinity of the absorption edge, among the overlapping wavelength regions. Therefore, it is possible to change the color of the illumination light emitted from the light emitting section efficiently by largely changing the light emission efficiency of either the first phosphor or the second phosphor.

  Further, according to the above configuration, the excitation light source can adjust the color of the illumination light emitted from the light emitting unit by changing the wavelength of the excitation light in a narrow wavelength region among the overlapping wavelength regions. As a result, a mechanism for changing the wavelength of the excitation light can be simplified.

  Further, in the light emitting device according to the present invention, the first phosphor emits fluorescence having a shorter peak wavelength than the second phosphor, and the excitation light source includes the overlapping wavelength region, It is preferable to change the wavelength of the excitation light in the absorption edge on the longest wave side of the first phosphor and the wavelength region near the absorption edge.

  In general, it is known that when the phosphor is excited in the wavelength region of the absorption edge, the luminous efficiency of the phosphor changes greatly.

  According to the above configuration, the excitation light source changes the wavelength of the excitation light in the absorption region of the first phosphor and the wavelength region in the vicinity of the absorption region in the overlapping wavelength region. The luminous efficiency of the illumination light emitted from the light emitting section can be changed efficiently.

  Moreover, according to said structure, the wavelength of excitation light in the absorption edge in the longest wave side of the 1st fluorescent substance which emits fluorescence whose peak wavelength is shorter than a 2nd fluorescent substance, and the wavelength range of the said absorption edge vicinity For example, when a blue phosphor is used as the first phosphor and a yellow phosphor is used as the second phosphor, near ultraviolet light is used as the excitation light, and the fluorescence emitted from the blue phosphor is yellow. Since the illumination light color can be easily changed by changing relative to the fluorescence emitted from the phosphor, it is preferable from the viewpoint of implementation.

  In the light emitting device according to the present invention, it is preferable that the excitation light source is a semiconductor light emitting element, and further includes a temperature adjusting unit that adjusts a temperature of the semiconductor light emitting element.

  The above configuration further includes a temperature adjustment unit that adjusts the temperature of the semiconductor light emitting element, which is an excitation light source, so that the wavelength of the excitation light is changed by adjusting the temperature of the semiconductor light emitting element by the temperature adjustment unit. be able to.

  For example, it is possible to control the wavelength of the excitation light to be shortened by lowering the temperature of the semiconductor light emitting element by the temperature adjusting unit.

  Therefore, according to said structure, the wavelength of the excitation light radiate | emitted from a single excitation light source can be changed.

  In the light-emitting device according to the present invention, it is preferable that the excitation light source includes a plurality of light sources that emit excitation light having different wavelengths, and the plurality of light sources selectively emit the excitation light having different wavelengths. .

  In the above configuration, the excitation light source includes a plurality of light sources that emit excitation light with different wavelengths, and the plurality of light sources selectively emit excitation light with different wavelengths.

  Therefore, according to said structure, the wavelength of the excitation light radiate | emitted from an excitation light source can be changed by selectively driving a some light source and emitting the excitation light of a different wavelength.

  Moreover, according to said structure, since the wavelength of the excitation light irradiated to a light emission part can be changed greatly, the color of illumination light can be changed significantly.

  In the light emitting device according to the present invention, the excitation light is preferably laser light.

  According to the above configuration, it becomes easy to install the excitation light source and the light emitting unit including the phosphor apart from each other, so that conduction of heat generated in the excitation light source to the light emitting unit is suppressed, and the temperature of the light emitting unit is reduced. A decrease in luminous efficiency of the phosphor due to the rise can be suppressed. In general, phosphors show a decrease in luminous efficiency as the temperature rises, but by placing the excitation light source and the light emitting part apart, the influence of heat generated by the excitation light source is not given to the light emitting part, The temperature of the excitation light source can be controlled.

  Further, by using laser light as the excitation light, the excitation light can be focused on a small spot and irradiated onto the light emitting portion. Therefore, it is possible to realize a light emitting part (point light source) with a small size and high brightness as compared with a conventional device including an LED as a light emitting part, and the color of illumination light emitted from this small light emitting part. Can be adjusted.

  The vehicle headlamp according to the present invention includes the light-emitting device in order to solve the above problems.

  According to said structure, the vehicle headlamp which can adjust the color of illumination light can be implement | achieved, suppressing generation | occurrence | production of a color nonuniformity with the more simplified apparatus structure.

  Thus, for example, when it is raining or foggy, it is possible to prevent illumination light from being irregularly reflected by irradiating illumination light with a relatively low color temperature that contains a relatively long wavelength component. Can be improved. On the other hand, visibility can be improved by irradiating illumination light having a high color temperature and containing a relatively large amount of short wavelength components in fine weather.

  In order to solve the above-described problem, a color adjusting method for a light-emitting device according to the present invention absorbs excitation light emitted from an excitation light source and emits fluorescence, and the first phosphor. Is a color adjustment method for a light-emitting device including a light-emitting unit including at least a second phosphor that emits fluorescence having different peak wavelengths, wherein the absorption wavelength region of the first phosphor and the second fluorescence And a wavelength control step of changing the wavelength of the excitation light in a wavelength region where the absorption wavelength region of the body overlaps each other.

  According to said method, the color adjustment method of the light-emitting device which can adjust the color of illumination light can be implement | achieved, suppressing generation | occurrence | production of color unevenness.

  As described above, the light-emitting device according to the present invention includes an excitation light source that emits excitation light and the excitation light emitted from the excitation light source in order to solve the above-described problem. A light emitting section including at least a first phosphor that absorbs and emits fluorescence, and a second phosphor that emits fluorescence having a peak wavelength different from that of the first phosphor; The wavelength of the excitation light is changed in a wavelength region where the absorption wavelength region of the first phosphor and the absorption wavelength region of the second phosphor overlap each other.

  The color adjustment method for a light emitting device according to the present invention includes an excitation light emitting step for emitting excitation light, and a first phosphor that emits fluorescence by absorbing the excitation light emitted in the excitation light emitting step. A light emitting step that emits a light emitting unit including at least a second phosphor that emits fluorescence having a peak wavelength different from that of the first phosphor, an absorption wavelength region of the first phosphor, and the second phosphor And a wavelength control step of changing the wavelength of the excitation light in a wavelength region where the absorption wavelength regions of the phosphors overlap each other.

  Therefore, according to the present invention, there is an effect that it is possible to realize a light emitting device and a color adjustment method for the light emitting device that can adjust the color of illumination light while suppressing the occurrence of color unevenness.

1 is a cross-sectional view illustrating a schematic configuration of a headlamp according to Embodiment 1. FIG. FIG. 2 is an enlarged cross-sectional view showing the Peltier unit shown in FIG. 1. It is a graph which shows the excitation spectrum and emission spectrum of a fluorescent substance, (a) shows the spectrum of a blue fluorescent substance, (b) shows the spectrum of a green fluorescent substance, (c) shows the spectrum of a yellow fluorescent substance. , (D) shows the spectrum of the red phosphor. It is a table | surface which shows the result of having simulated the change of the color temperature (color tint) of illumination light when changing the wavelength of the laser beam irradiated to the light emission part containing a blue fluorescent substance and a yellow fluorescent substance. It is a table | surface which shows the result of having simulated the change of the color temperature (color tint) of illumination light when changing the wavelength of the laser beam irradiated to the light emission part containing a blue fluorescent substance and a yellow fluorescent substance. It is a flowchart which shows an example of the flow of a process in the headlamp shown by FIG. It is a table | surface which shows the change of the wavelength of a laser beam, and the color temperature (color tint) of illumination light when the temperature of the semiconductor laser element shown by FIG. 1 is changed. It is sectional drawing which shows the 1st modification of the headlamp shown by FIG. It is sectional drawing which shows the 2nd modification of the headlamp shown by FIG. FIG. 10 is a cross-sectional view showing a third modification of the headlamp shown in FIG. 1. 6 is a cross-sectional view illustrating a schematic configuration of a headlamp according to a second embodiment. FIG. 12 is a flowchart illustrating an example of a process flow in the headlamp illustrated in FIG. 11. 12 is a table showing changes in the wavelength of laser light and the color temperature (color) of illumination light when the semiconductor laser element shown in FIG. 11 is switched. (A) And (b) is a perspective view which shows schematic structure of the conventional lighting equipment.

Embodiment 1
An embodiment of a light emitting device according to the present invention will be described below with reference to FIGS. In the present embodiment, an automobile headlamp (vehicle headlamp) including the light emitting device according to the present invention will be described as an example.

  However, the light-emitting device according to the present invention can also be applied to a headlamp other than an automobile or other lighting devices.

<Configuration of headlamp 1a>
First, the configuration of the headlamp 1a according to the present embodiment will be described with reference to FIGS. The headlamp 1a uses, as illumination light, fluorescence generated by irradiating the light emitting unit 5 including phosphor with laser light emitted from the semiconductor laser element 2.

  FIG. 1 is a cross-sectional view showing a schematic configuration of a headlamp 1a according to the present embodiment, and FIG. 2 is an enlarged view showing a Peltier unit 3 shown in FIG. As shown in FIG. 1, the headlamp 1 a includes a semiconductor laser element (excitation light source) 2, a Peltier unit (temperature adjusting unit) 3, a lens 4, a light emitting unit 5, a parabolic mirror 6, and a metal base 8. And. Hereinafter, the structure of each part with which the headlamp 1a is provided is demonstrated.

(Semiconductor laser element 2)
The semiconductor laser element 2 is a semiconductor light emitting element that functions as an excitation light source that emits laser light (excitation light). The semiconductor laser element 2 may have one light emitting point per chip, or may have a plurality of light emitting points per chip. The wavelength of the laser beam emitted from the semiconductor laser element 2 is, for example, 380 nm (blue violet) to 480 nm (blue), but is not limited thereto, and is appropriately selected according to the type of phosphor included in the light emitting unit 5. Is done.

  Instead of the semiconductor laser element 2, a light emitting diode (LED) or the like can be used as an excitation light source.

(Peltier unit 3)
The Peltier unit 3 is for changing the wavelength of the laser light emitted from the semiconductor laser element 2. Specifically, the Peltier unit 3 changes the wavelength of the laser beam emitted from the semiconductor laser element 2 by controlling the temperature of the semiconductor laser element 2.

  As shown in FIG. 2, the Peltier unit 3 includes a heat sink 31, a Peltier element 32, a heat radiating unit 33, and a cooling fan 34.

  The heat sink 31 is made of a material having high thermal conductivity such as aluminum, and efficiently exchanges heat with the semiconductor laser element 2 disposed on the heat sink 31.

  The Peltier element 32 is an element that absorbs heat on one surface and generates heat on the other surface, and can change the endothermic surface and the heat generating surface by changing the direction of the flowing current. The Peltier element 32 is disposed between the heat sink 31 and the heat radiating part 33, and exchanges heat between the semiconductor laser element 2 and the heat radiating part 33 by controlling the current value of the Peltier element 32. be able to.

  The heat radiating section 33 radiates heat received from the heat radiating surface of the Peltier element 32 to the atmosphere. The heat radiating part 33 is made of a material having high thermal conductivity, and can efficiently exchange heat with the Peltier element 32. Moreover, the several fin is formed in the thermal radiation part 33, and the thermal radiation efficiency is improved by increasing the contact area with air | atmosphere.

  The cooling fan 34 cools the heat radiating part 33. Specifically, the cooling fan 34 improves the heat radiation efficiency in the heat radiating part 33 by cooling the heat radiating part 33 by applying wind to the heat radiating part 33.

  By controlling the Peltier unit 3 having such a configuration, the wavelength of the laser light emitted from the semiconductor laser element 2 can be changed. As will be described later, the wavelength of the laser light emitted from the semiconductor laser element 2 changes according to the temperature of the semiconductor laser element 2. Therefore, for example, by reducing the temperature of the semiconductor laser element 2 by the Peltier unit 3, it is possible to perform control such as shortening the wavelength of the laser light emitted from the semiconductor laser element 2.

  The operation of each part of the headlamp 1a including the Peltier unit 3 is controlled by a control unit (not shown). Further, although the Peltier unit 3 is used as a temperature adjusting unit for adjusting the temperature of the semiconductor laser element 2, a water cooling method, a compressor, or the like may be used instead of the Peltier unit 3.

(Lens 4)
The lens 4 adjusts the irradiation range of the laser light emitted from the semiconductor laser element 2. Specifically, the lens 4 adjusts the irradiation range of the laser light according to the size of the light emitting unit 5 so that the laser light emitted from the semiconductor laser element 2 is appropriately irradiated to the light emitting unit 5. (For example, reduction).

(Light emitting part 5)
The light emitting part 5 receives the laser light emitted from the semiconductor laser element 2 and emits fluorescence (illumination light). The light emitting unit 5 includes at least two kinds of phosphors (first phosphor and second phosphor) that absorb the laser beam irradiated by the semiconductor laser element 2 and emit fluorescence. Specifically, the light emitting unit 5 includes at least a first phosphor that emits fluorescence by absorbing laser light, and a second phosphor that emits fluorescence having a peak wavelength different from that of the first phosphor. It is.

  The light-emitting portion 5 includes phosphor particles dispersed on the inside of a sealing material, phosphor particles solidified, or a substrate made of a material having high thermal conductivity. Such as those deposited. Since the light emitting unit 5 converts the laser light into fluorescence, it can be said to be a wavelength conversion element.

  The light emitting unit 5 is disposed on the metal base 8 and at a substantially focal position of the parabolic mirror 6. Therefore, the fluorescence emitted from the light emitting unit 5 is reflected on the reflection curved surface of the parabolic mirror 6 so that the optical path is controlled, and the illumination light can be efficiently collected far away. Note that an antireflection structure for preventing the reflection of the laser beam may be formed on the upper surface of the light emitting unit 5.

The phosphor contained in the light emitting unit 5 includes an oxynitride phosphor (for example, sialon phosphor) or a III-V group compound semiconductor nanoparticle phosphor (for example, indium phosphorus: InP).
Alternatively, a YAG phosphor can be used. These phosphors have high heat resistance against high-power (and / or light density) laser light emitted from the semiconductor laser element 2, and are optimal for laser illumination light sources. However, the phosphor of the light emitting unit 5 is not limited to the above-described phosphor, and may be another phosphor such as a nitride phosphor.

Specifically, as the phosphor included in the light emitting section 5, for example, a blue phosphor (BaMgAl ₁₀ O ₁₇ : Eu, (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu, LaAl (SiAl) ₆ N ₉ O: Ce), green phosphor (Ba ₃ Si ₆ O ₁₂ N ₂ : Eu), β-sialon: Eu, Y ₃ (Al, Ga) ₅ O ₁₂ : Ce), yellow Phosphor (Y ₃ Al ₅ O ₁₂ : Ce, Ca _x (Si, Al) ₁₂ (O, N) ₁₆ : Eu,), red phosphor (CaAlSiN ₃ : Eu, (Sr _0.8 Ca _0.2 ) AlSiN ₃ : Eu) and the like.

  The law stipulates that the illumination light of the headlamp 1a must be white having a predetermined range of chromaticity. For this reason, the light emitting unit 5 includes a phosphor selected so that the illumination light is white.

  For example, it is possible to obtain white illumination light by including a blue phosphor (first phosphor) and a yellow phosphor (second phosphor) in the light emitting unit 5 and irradiating near-ultraviolet laser light. it can.

  Further, by irradiating the light emitting unit 5 including the blue phosphor and the yellow phosphor with laser light having a long wavelength, illumination light having excellent visibility in rainy weather can be obtained. Alternatively, by irradiating the light emitting unit 5 including the blue phosphor and the yellow phosphor with laser light having a short wavelength, it is possible to obtain illumination light having excellent visibility in fine weather.

  In addition, the fluorescent substance contained in the light emission part 5 is not restricted to two types, Three or more types may be sufficient. For example, blue, green, and red phosphors may be included in the light emitting unit 5 and white light illumination light may be realized by irradiating a 405 nm laser beam.

(Parabolic mirror 6)
The parabolic mirror 6 reflects the illumination light emitted from the light emitting unit 5 and forms a light beam that travels within a predetermined solid angle. For example, the parabolic mirror 6 may be a member having a metal thin film formed on the surface thereof or a metal member.

  The parabolic mirror 6 has at least a part of a partial curved surface obtained by cutting a curved surface (parabolic curved surface) formed by rotating the parabola with the axis of symmetry of the parabola as a rotational axis by a plane including the rotational axis. , Included in its reflective surface. When the parabolic mirror 6 is viewed from the front, the opening 6a (illumination light exit) is semicircular.

  The semiconductor laser element 2 is disposed outside the parabolic mirror 6, and the parabolic mirror 6 is provided with a window portion 7 that transmits or passes laser light. The window 7 may be an opening or may include a transparent member that can transmit laser light. For example, a transparent plate provided with a filter that transmits laser light and reflects white light (fluorescence of the light emitting unit 5) may be provided as the window unit 7. According to this configuration, the fluorescence of the light emitting unit 5 can be prevented from leaking from the window unit 7.

  A part that is not a parabola may be included in a part of the parabola mirror 6. Further, instead of the parabolic mirror 6 having the semicircular opening 6a, a parabolic mirror having a closed circular opening or a part including the parabolic mirror may be used. Alternatively, an elliptical mirror or a hemispherical mirror may be used.

(Metal base 8)
The metal base 8 is a plate-like support member that supports the light emitting unit 5 and is made of metal (for example, aluminum or silver). Therefore, the metal base 8 has a high thermal conductivity and can efficiently dissipate the heat generated in the light emitting unit 5.

  In addition, the support member which supports the light emission part 5 is not limited to what consists of metals, The member containing materials (glass, sapphire, etc.) with high heat conductivity other than a metal may be sufficient. However, the surface of the metal base 8 that comes into contact with the light emitting portion 5 preferably functions as a reflecting surface. Since the surface is a reflecting surface, the fluorescence can be reflected by the reflecting surface and directed toward the parabolic mirror 6. Further, the laser light that has not been converted into fluorescence can be reflected by the reflection surface and directed again into the light emitting unit 5 to be converted into fluorescence.

  Since the metal base 8 is covered by the parabolic mirror 6, it can be said that the metal base 8 has a surface facing the reflection curved surface (parabolic curved surface) of the parabolic mirror 6. It is preferable that the surface of the metal base 8 on the side where the light emitting unit 5 is provided is substantially parallel to the rotation axis of the paraboloid of the parabolic mirror 6 and substantially includes the rotation axis.

<Principle of color adjustment of illumination light>
Next, the principle of color adjustment of illumination light in the headlamp 1a will be described with reference to FIGS.

FIG. 3 is a graph showing an excitation spectrum (dotted line) and an emission spectrum (solid line) of the phosphor, wherein (a) shows the spectrum of the blue phosphor (BaMgAl ₁₀ O ₁₇ : Eu), and (b) shows the green color. The spectrum of the phosphor (Ba3Si ₆ O ₁₂ N ₂ : Eu) is shown, (c) is the spectrum of the yellow phosphor (Y ₃ Al ₅ O ₁₂ : Ce), and (d) is the red phosphor (CaAlSiN ₃ : The spectra of Eu and (Sr _0.8 Ca _0.2 ) AlSiN ₃ : Eu) are shown. 3A and 3B are cited from Non-Patent Document 1, and FIGS. 3C and 3D are cited from Non-Patent Document 2.

  As shown in FIGS. 3A to 3D, the excitation spectrum of the phosphor is different for each type of phosphor, and changes according to the wavelength of the laser beam (excitation light). Therefore, the emission intensity of the fluorescence emitted from each phosphor can be controlled by changing the wavelength of the laser beam.

  Therefore, for example, when the light emitting unit 5 includes a blue phosphor and a yellow phosphor, the wavelength of the laser light is changed in a wavelength region where the absorption wavelength regions of the blue phosphor and the yellow phosphor overlap with each other, whereby the blue fluorescence Since the ratio of the fluorescence emitted from the body and the fluorescence emitted from the yellow phosphor changes, the color of the illumination light emitted from the light emitting unit 5 can be adjusted.

  In addition, by exciting the phosphor with laser light corresponding to the wavelength region of the absorption edge in the excitation spectrum of the phosphor, the emission intensity (luminescence efficiency) of the phosphor greatly changes. Here, the absorption edge refers to a wavelength region in which the emission intensity of the phosphor greatly changes when the excitation wavelength is changed. For example, in the case of the blue phosphor shown in FIG. 3A, the amount of change in emission intensity in the excitation spectrum in the wavelength region near 250 nm and in the vicinity of 400 nm is large. Therefore, the emission intensity of the blue phosphor changes greatly by changing the wavelength of the laser light in the vicinity of 250 nm or 400 nm. Thus, by changing the wavelength of the laser light in the wavelength region near the absorption edge and near the absorption edge of the phosphor, the emission intensity of the phosphor can be changed efficiently.

  Therefore, for example, when the light emitting unit 5 includes a blue phosphor and a yellow phosphor, the absorption end of the blue phosphor or the yellow phosphor out of the wavelength regions where the absorption wavelength regions of the blue phosphor and the yellow phosphor overlap each other. By changing the wavelength of the laser light in the absorption edge of the light source and in the wavelength region near the absorption edge, the light emission intensity of either the blue phosphor or the yellow phosphor is greatly changed and emitted from the light emitting unit 5. The color of the illumination light can be adjusted.

  Specifically, the fluorescence emitted from the blue phosphor is changed by changing the wavelength of the near-ultraviolet laser light in the absorption edge on the longest wave side of the blue phosphor and the wavelength region near the absorption edge (near 400 nm). Since the ratio can be mainly changed, the color of the illumination light emitted from the light emitting unit 5 can be adjusted efficiently.

4 and 5 show the results of simulating changes in the color temperature (color) of the illumination light when the wavelength of the laser light applied to the light emitting unit 5 including the blue phosphor and the yellow phosphor is changed. It is a table | surface which shows. FIG. 4 shows a simulation result when BaMgAl ₁₀ O ₁₇ : Eu is used as the blue phosphor and Ca _x (Si, Al) ₁₂ (O, N) ₁₆ : Eu is used as _the yellow phosphor. The simulation results are shown when LaAl (SiAl) ₆ N ₉ O: Ce is used as the blue phosphor and Ca _x (Si, Al) ₁₂ (O, N) ₁₆ : Eu is used as _the yellow phosphor.

As shown in FIG. 4, when BaMgAl ₁₀ O ₁₇ : Eu is used as the blue phosphor and Ca _x (Si, Al) ₁₂ (O, N) ₁₆ : Eu is used as _the yellow phosphor, the wavelength of the laser beam is 390 nm. By changing to ˜415 nm, the color of the illumination light emitted from the light emitting unit 5 can be changed from day white (color temperature: 4760K) to warm white (color temperature: 3430K).

In addition, as shown in FIG. 5, when using LaAl (SiAl) ₆ N ₉ O: Ce as the blue phosphor and Ca _x (Si, Al) ₁₂ (O, N) ₁₆ : Eu as _the yellow phosphor, By changing the wavelength of the laser light from 390 nm to 415 nm, the color of the illumination light emitted from the light emitting unit 5 can be changed from daylight color (color temperature: 5740 K) to white color (color temperature: 4270 K).

  In this way, the color of the illumination light emitted from the single light emitting unit 5 is changed by changing the wavelength of the laser light from 390 nm to 415 nm which is the wavelength region near the absorption edge and near the absorption edge of the blue phosphor. Can be changed. This is included in the illumination light emitted from the light emitting unit 5 because the emission intensity of the blue phosphor has changed greatly by changing the wavelength of the laser light in the absorption region of the blue phosphor and the wavelength region near the absorption end. This is because the ratio of the blue component to be changed has changed.

  Note that the change in color temperature shown in FIGS. 4 and 5 is an example, and the light is emitted from the light emitting unit 5 by changing the wavelength band of the laser light to be changed, the type of phosphor, the blending ratio of the phosphor, and the like. The illumination light can be adjusted to a desired color.

  For example, in addition to a combination of a blue phosphor and a yellow phosphor, a blue phosphor, a green phosphor, and a red phosphor may be combined. Further, even when the light emitting unit 5 does not include a blue phosphor, laser light in the wavelength region near the absorption edge and the absorption edge of any one of the plurality of phosphors included in the light emitting unit 5 The color of the illumination light can be adjusted by changing the wavelength of.

<Processing in the headlamp 1a>
Next, processing in the headlamp 1a (color adjustment method of the light emitting device) will be described with reference to FIGS. FIG. 6 is a flowchart showing an example of a process flow in the headlamp 1a.

  As shown in FIG. 6, when receiving an instruction to turn on the headlamp 1a, the control unit (not shown) drives the semiconductor laser element 2 to emit laser light (S1). Specifically, the control unit causes the semiconductor laser element 2 to emit laser light by supplying power to the semiconductor laser element 2. At this time, the laser beam may be emitted while controlling the Peltier unit 3 and keeping the temperature of the semiconductor laser element 2 constant.

  Next, the light emitting unit 5 is caused to emit light by irradiating the light emitting unit 5 with laser light emitted from the semiconductor laser element 2 (S2). Thereby, the illumination light emitted from the light emitting unit 5 is reflected and collected by the parabolic mirror 6 and then irradiated from the opening 6a.

  Next, when receiving an instruction to adjust the color of the illumination light, the control unit controls the Peltier unit 3 to change the wavelength of the laser light emitted from the semiconductor laser element 2 (S3: wavelength control step). ). Specifically, the control unit drives the Peltier unit 3 to change the temperature of the semiconductor laser element 2. Thereby, the wavelength of the laser beam emitted from the semiconductor laser element 2 can be changed.

FIG. 7 is a table showing changes in the wavelength of the laser light and the color temperature (color) of the illumination light when the temperature of the semiconductor laser element 2 is changed. In FIG. 7, a blue phosphor (BaMgAl ₁₀ O ₁₇ : Eu), a green phosphor (Ba ₃ Si ₆ O ₁₂ N ₂ : Eu), and a yellow phosphor (Ca _x (Si, Al) ₁₂ (O, N) ) ₁₆ : Eu) is a value in the case of irradiating the light emitting part 5 blended at a mass ratio of 16: 1: 8 with laser light.

  As shown in FIG. 7, when the controller drives the Peltier unit 3 to change the temperature of the semiconductor laser element 2 from 60 ° C. to 20 ° C., the wavelength of the laser light emitted from the semiconductor laser element 2 is It changes from 413 nm to 410 nm.

  Therefore, by controlling the Peltier unit 3 to change the temperature of the semiconductor laser element 2 in the range of 20 ° C. to 60 ° C., the color of the illumination light emitted from the light emitting unit 5 is white (color temperature: 4030K). ) To warm white (color temperature: 3760K).

  As described above, according to the headlamp 1 a, the color of the illumination light emitted from the single light emitting unit 5 can be adjusted by controlling the temperature of the semiconductor laser element 2.

  Note that the flowchart shown in FIG. 6 shows a method of adjusting the color of the illumination light in a state where the illumination light is irradiated, but the present invention is not limited to this. For example, the Peltier unit control step (S3) may be performed simultaneously with the emission step (S1) or before the emission step (S1). Thereby, in the light emission step (S2), illumination light adjusted to a desired color can be irradiated.

<Overview of Embodiment 1>
As described above, the headlamp 1a according to this embodiment includes the semiconductor laser element 2 that emits laser light, the blue phosphor that emits fluorescence by absorbing the laser light emitted from the semiconductor laser element 2, and the blue phosphor. And a Peltier unit 3 that adjusts the temperature of the semiconductor laser element 2, and the semiconductor laser element 2 has an absorption wavelength region of the blue phosphor. The wavelength of the laser light is changed in a wavelength region where the absorption wavelength region of the yellow phosphor overlaps with each other.

  According to the headlamp 1 a, the color of the illumination light emitted from the single light emitting unit 5 can be adjusted by controlling the temperature of the semiconductor laser element 2. Therefore, as compared with a conventional configuration in which light emitted from a plurality of light emitting units (LEDs) is mixed to adjust the color of illumination light, the device configuration can be simplified and color unevenness can be reduced. Occurrence can be suppressed.

  Therefore, according to the present embodiment, it is possible to realize the headlamp 1a capable of adjusting the color of the illumination light while suppressing the occurrence of color unevenness with a more simplified device configuration.

  Thereby, for example, when it is raining or foggy, illumination light having a relatively long wavelength can be irradiated to prevent irregular reflection of the illumination light and improve visibility. On the other hand, visibility can be improved by irradiating illumination light having a relatively short wavelength in fine weather.

  In addition, according to the present embodiment, since the laser light can be focused and irradiated onto the light emitting unit 5, the size of the light emitting unit 5 can be reduced as compared with the configuration using the conventional LED, and the brightness can be increased. A simple headlamp 1a can be realized.

  In the above description, the semiconductor laser element 2 is used as the excitation light source, but an LED may be used. In this case, for example, the light emitting unit 5 including the phosphor provided on the LED chip serving as the excitation light source is disposed at the focal position of the parabolic mirror 6, and the temperature of the LED chip is controlled, thereby coloring the illumination light. Can be adjusted.

<Modification>
Next, modified examples of the headlamp 1a according to the present embodiment will be described with reference to FIGS. In the following modifications 1 to 3, a configuration in which fluorescence (illumination light) is projected using a projection lens 9 instead of the parabolic mirror 6 will be described.

(Modification 1)
FIG. 8 is a cross-sectional view showing a first modification of the headlamp 1a shown in FIG. The headlamp 1A shown in FIG. 8 is provided with a projection lens 9 instead of the parabolic mirror 6, and the bottom surface 5b of the light emitting unit 5 is irradiated with laser light, and fluorescence is emitted from the top surface 5a facing the bottom surface 5b. 1 is mainly different from the headlamp 1a shown in FIG. 1 in that the transmission type light emission principle is used.

  As shown in FIG. 8, the headlamp 1 </ b> A includes a semiconductor laser element 2, a Peltier unit 3, a lens 4, a light emitting unit 5, a projection lens 9, and a transparent plate 13.

  The projection lens 9 transmits a fluorescent light emitted from the light emitting unit 5 and refracts the fluorescent light to form a light bundle that travels within a predetermined solid angle. By using the projection lens 9 instead of the parabolic mirror 6, the headlamp 1A can be downsized.

  In the headlamp 1 </ b> A, the light emitting unit 5 is disposed on a transparent plate 13 such as glass so as to overlap the focal position of the projection lens 9, and laser light is applied to the bottom surface 5 b of the light emitting unit 5 through the transparent plate 13. Is irradiated.

  In the headlamp 1A, the light emitting unit 5 receives laser light incident from the bottom surface 5b in contact with the transparent plate 13, and emits fluorescence from the top surface 5a facing the bottom surface 5b toward the projection lens 9. The projection lens 9 transmits illumination light that travels within a predetermined solid angle by transmitting the fluorescence emitted from the light emitting unit 5 and refracting the fluorescence.

  As described above, according to the first modification, the projection type headlamp 1A capable of adjusting the color of the illumination light while suppressing the occurrence of color unevenness can be realized with a more simplified device configuration. .

(Modification 2)
FIG. 9 is a cross-sectional view showing a second modification of the headlamp 1a shown in FIG. In FIG. 9, the semiconductor laser element 2, the Peltier unit 3, and the lens 4 are omitted.

  The headlamp 1B shown in FIG. 9 uses a reflection-type light emission principle in which the upper surface 5a of the light emitting unit 5 is irradiated with laser light, and fluorescence is emitted from the upper surface 5a irradiated with the laser light. This is mainly different from the headlamp 1A using the transmission type light emission principle shown in FIG.

  As shown in FIG. 9, the headlamp 1 </ b> B includes a light emitting unit 5, a projection lens 9, and a metal base 14.

  The metal base 14 supports the light emitting unit 5, and has a function of radiating heat generated in the light emitting unit 5 when irradiated with laser light through a contact surface in contact with the light emitting unit 5. For this reason, it is preferable to use a metal material such as aluminum or silver, which easily conducts heat, for the metal base 14, but the type is not particularly limited as long as the material has high heat conductivity.

  Further, the surface of the metal base 14 that comes into contact with the light emitting portion 5 is subjected to reflection processing, and functions as a reflection surface. Therefore, the laser light incident from the upper surface 5a of the light emitting unit 5 can be directed again to the inside of the light emitting unit 5 by being reflected by the reflecting surface, so that the utilization efficiency of the laser light can be improved.

  In the headlamp 1B, the light emitting unit 5 receives laser light incident from the upper surface 5a and emits fluorescence from the upper surface 5a toward the projection lens 9. The projection lens 9 irradiates illumination light that travels within a predetermined solid angle by transmitting the fluorescence emitted from the light emitting unit 5 and refracting the fluorescence.

  As described above, according to the second modification, the projection type headlamp 1B using the reflection type light emission principle can be realized.

(Modification 3)
FIG. 10 is a cross-sectional view showing a third modification of the headlamp 1a shown in FIG. In FIG. 10, the semiconductor laser element 2, the Peltier unit 3, and the lens 4 are not shown.

  The headlamp 1C shown in FIG. 10 is further provided with an elliptical mirror 15 in addition to the projection lens 9 in order to accurately project the fluorescence emitted from the light emitting unit 5, in that the headlamp shown in FIG. Mainly different from 1B.

  As shown in FIG. 10, the headlamp 1 </ b> C includes a light emitting unit 5, a projection lens 9, a metal base 14, and an elliptical mirror 15.

  The elliptical mirror 15 has a first focal point f1 and a second focal point f2, and the light emitting unit 5 is disposed on the metal base 14 so that the center of the light emitting unit 5 is located at the first focal point f1. ing.

  The projection lens 9 is provided so that the position of the focal point of the projection lens 9 and the position of the second focal point f2 of the elliptical mirror 15 overlap.

  In the headlamp 1C, the fluorescence emitted from the light emitting unit 5 disposed at the first focal point f1 is reflected by the elliptical mirror 15 toward the second focal point f2. Then, the projection lens 9 irradiates illumination light that travels within a predetermined solid angle by transmitting the fluorescence that has passed through the second focal point f2 and refracting the fluorescence. At this time, it can be considered that the virtual light source exists at the second focal point f2 of the elliptical mirror 15, that is, the focal point of the projection lens 9, and the illumination light from the virtual light source is projected.

  As described above, according to the third modification, by arranging the light emitting unit 5, the projection lens 9, the metal base 14, and the elliptical mirror 15 according to the above positional relationship, it is possible to efficiently collect fluorescence. In addition, a projection type headlamp 1C that can efficiently radiate the condensed light to the outside can be realized.

[Embodiment 2]
The following will describe another embodiment of the light emitting device according to the present invention with reference to FIGS. For convenience of explanation, members having the same functions as those in the drawings explained in the first embodiment are given the same reference numerals and explanations thereof are omitted.

  The headlamp 1b according to the present embodiment is different from the headlamp 1b according to the first embodiment in that the color of irradiated light is adjusted using two semiconductor laser elements 2a and 2b (excitation light source, semiconductor light emitting element, and light source). Mainly different.

<Configuration of headlamp 1b>
First, the configuration of the headlamp 1b according to the present embodiment will be described with reference to FIG.

  FIG. 11 is a cross-sectional view showing a schematic configuration of the headlamp 1b according to the present embodiment. As shown in FIG. 11, the headlamp 1 b includes semiconductor laser elements 2 a and 2 b, a lens 4, a light emitting unit 5, a parabolic mirror 6, and a metal base 8.

(Semiconductor laser elements 2a and 2b)
The semiconductor laser elements 2a and 2b are semiconductor light emitting elements that function as an excitation light source that emits laser light (excitation light). The semiconductor laser elements 2a and 2b respectively emit laser beams having different wavelengths. For example, the wavelength of the laser light emitted from the semiconductor laser element 2a is 410 nm, and the wavelength of the laser light emitted from the semiconductor laser element 2b is 401 nm. However, the type of phosphor contained in the light emitting unit 5 is not limited thereto. It is appropriately selected depending on.

  Note that an optical fiber may be connected to the semiconductor laser elements 2a and 2b, and laser light may be emitted from the emission end of the optical fiber. Thereby, since the arrangement position of the semiconductor laser elements 2a and 2b can be changed, the degree of freedom in device design can be improved.

(Lens 4)
The lenses 4 are respectively arranged corresponding to the semiconductor laser elements 2a and 2b, and adjust the irradiation range of the laser light emitted from the semiconductor laser elements 2a and 2b. Specifically, the lens 4 adjusts the irradiation range of the laser light to the size of the light emitting unit 5 so that the laser light emitted from the semiconductor laser elements 2 a and 2 b is appropriately irradiated to the light emitting unit 5. Adjust (for example, reduce). It should be noted that the irradiation range of each laser beam emitted from the semiconductor laser elements 2a and 2b can be adjusted by one lens 4.

(Parabolic mirror 6)
The parabolic mirror 6 reflects the fluorescence generated by the semiconductor laser element 2a or the semiconductor laser element 2b and forms a light beam (illumination light) that travels within a predetermined solid angle. The semiconductor laser elements 2 a and 2 b are disposed outside the parabolic mirror 6, and the parabolic mirror 6 is provided with a window portion 7 that transmits or passes laser light. The window 7 may be provided with two windows 7 corresponding to the two semiconductor laser elements 2a and 2b, respectively, or one window 7 common to the two semiconductor laser elements 2a and 2b. It may be provided.

<Processing in the headlamp 1b>
Next, processing in the headlamp 1b (coloring adjustment method of the light emitting device) will be described with reference to FIGS. FIG. 12 is a flowchart illustrating an example of a process flow in the headlamp 1b.

  As shown in FIG. 12, when receiving an instruction to turn on the headlamp 1a, the control unit (not shown) drives the semiconductor laser element 2a to emit laser light (S1).

  Next, the light emitting unit 5 is caused to emit light by irradiating the light emitting unit 5 with laser light emitted from the semiconductor laser element 2a (S2). Thereby, the illumination light emitted from the light emitting unit 5 is reflected and collected by the parabolic mirror 6 and then irradiated from the opening 6a.

  Next, when the control unit receives an instruction to adjust the color of the illumination light, the control unit switches driving of the semiconductor laser elements 2a and 2b (S13: wavelength control step). Specifically, the control unit stops the driving of the semiconductor laser element 2a and simultaneously drives the semiconductor laser element 2b to emit laser light.

  Note that although the flowchart shown in FIG. 12 shows a method for adjusting the color of the illumination light in a state where the illumination light is irradiated, the present invention is not limited to this. For example, the semiconductor laser switching step (S13) may be performed simultaneously with the emission step (S1) or before the emission step (S1). Thereby, in the light emission step (S2), illumination light adjusted to a desired color can be irradiated.

FIG. 13 is a table showing changes in the wavelength of the laser light and the color temperature (color) of the illumination light when the semiconductor laser elements 2a and 2b are switched. In FIG. 13, a blue phosphor (BaMgAl ₁₀ O ₁₇ : Eu), a green phosphor (Ba ₃ Si ₆ O ₁₂ N ₂ : Eu), and a yellow phosphor (Ca _x (Si, Al) ₁₂ (O, N) ) ₁₆ : Eu) is a value in the case of irradiating the light emitting part 5 blended at a mass ratio of 16: 1: 8 with laser light.

  As shown in FIG. 13, when the control unit switches the driving from the semiconductor laser element 2a to the semiconductor laser element 2b, the wavelength of the laser light irradiated to the light emitting unit 5 changes from 410 nm to 401 nm.

  Therefore, by changing the drive from the semiconductor laser element 2a to the semiconductor laser element 2b, the color of the illumination light emitted from the light emitting unit 5 is changed from white (color temperature: 4030K) to day white (color temperature: 5760K). Can be made.

  Thus, according to the headlamp 1b, the color of the illumination light emitted from the single light emitting unit 5 is adjusted by switching the driving of the semiconductor laser elements 2a and 2b that respectively emit laser beams having different wavelengths. can do.

  Further, according to the headlamp 1b, the wavelength of the laser light irradiated to the light emitting unit 5 is greatly changed compared to the configuration in which the temperature of the semiconductor laser element 2 is controlled as in the headlamp 1a according to the first embodiment. Can change the color of the illumination light.

<Overview of Embodiment 2>
As described above, the headlamp 1b according to this embodiment has the semiconductor laser elements 2a and 2b that selectively emit laser beams having different wavelengths and the laser beams emitted from the semiconductor laser element 2a or the semiconductor laser element 2b. A light emitting section 5 including at least a blue phosphor that absorbs and emits fluorescence and a yellow phosphor that emits fluorescence having a peak wavelength different from that of the first phosphor, and the semiconductor laser elements 2a and 2b are blue phosphors. In the wavelength region where the absorption wavelength region of the yellow phosphor and the absorption wavelength region of the yellow phosphor overlap each other, different wavelengths of laser light are selectively emitted.

  According to the headlamp 1b, the color of the illumination light emitted from the single light emitting unit 5 can be adjusted by selectively switching the driving of the semiconductor laser elements 2a and 2b. Therefore, as compared with a conventional configuration in which light emitted from a plurality of light emitting units (LEDs) is mixed to adjust the color of illumination light, the device configuration can be simplified and color unevenness can be reduced. Occurrence can be suppressed.

  Therefore, according to the present embodiment, it is possible to realize the headlamp 1b capable of adjusting the color of the illumination light while suppressing the occurrence of color unevenness with a more simplified device configuration.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and the embodiments can be obtained by appropriately combining technical means disclosed in different embodiments. The form is also included in the technical scope of the present invention.

  For example, a configuration in which a plurality of semiconductor laser elements are provided and the color of illumination light is adjusted by controlling the temperature of each semiconductor laser element may be employed.

[Supplement]
The light emitting device according to the present invention can also be expressed as follows. That is, when the light emitting device according to the present invention excites a plurality of phosphors having different emission wavelengths with a semiconductor light emitting element, the excitation wavelength is near the absorption edge at the shortest wavelength among the absorption edges of the phosphors contained. It is characterized by adjusting the color of the extracted illumination light by changing.

  The light-emitting device according to the present invention is characterized in that the excitation wavelength is changed by changing the temperature of the semiconductor light-emitting element.

  The light-emitting device according to the present invention is characterized in that a plurality of semiconductor elements having different excitation wavelengths are used and the excitation wavelength is changed.

  In the light-emitting device according to the present invention, the semiconductor light-emitting element is a laser.

  The light emitting device according to the present invention can be suitably applied to a lighting device, particularly a headlamp for a vehicle or the like.

1a Headlamp (light emitting device / vehicle headlamp)
1b Headlamp (light emitting device / vehicle headlamp)
1A Headlamp (light emitting device / vehicle headlamp)
1B Headlamp (light emitting device / vehicle headlamp)
1C Headlamp (light emitting device / vehicle headlamp)
2 Semiconductor laser element (excitation light source / semiconductor light emitting element)
2a Semiconductor laser element (excitation light source, semiconductor light emitting element, light source)
2b Semiconductor laser element (excitation light source / semiconductor light emitting element / light source)
3 Peltier unit (temperature adjustment unit)
DESCRIPTION OF SYMBOLS 5 Light emission part 6 Parabolic mirror 9 Projection lens 13 Transparent plate 14 Metal base 15 Elliptical mirror 31 Heat sink 32 Peltier element 33 Heat radiation part 34 Cooling fan S1 Output step S2 Light emission step S3 Peltier unit control step (wavelength control step)
S13 Semiconductor laser element switching step (wavelength control step)
f1 first focus f2 second focus

Claims (8)

An excitation light source that emits excitation light;
Light emission including at least a first phosphor that emits fluorescence by absorbing the excitation light emitted from the excitation light source, and a second phosphor that emits fluorescence having a peak wavelength different from that of the first phosphor. With
The light-emitting device, wherein the excitation light source changes the wavelength of the excitation light in a wavelength region where an absorption wavelength region of the first phosphor and an absorption wavelength region of the second phosphor overlap each other.   The excitation light source changes the wavelength of the excitation light in the wavelength region near the absorption edge and the absorption edge of the first phosphor or the absorption edge of the second phosphor among the overlapping wavelength regions. The light-emitting device according to claim 1. The first phosphor emits fluorescence having a shorter peak wavelength than the second phosphor,
The excitation light source changes a wavelength of the excitation light in an absorption edge on the longest wave side of the first phosphor and a wavelength area in the vicinity of the absorption edge among the overlapping wavelength ranges. The light emitting device according to claim 1. The excitation light source is a semiconductor light emitting element,
The light-emitting device according to claim 1, further comprising a temperature adjustment unit that adjusts a temperature of the semiconductor light-emitting element. As the excitation light source, comprising a plurality of light sources that emit excitation light of different wavelengths,
4. The light-emitting device according to claim 1, wherein the plurality of light sources selectively emit the excitation light having different wavelengths. 5.   6. The light emitting device according to claim 1, wherein the excitation light is laser light.   A vehicle headlamp comprising the light-emitting device according to claim 1. A light emitting unit including at least a first phosphor that emits fluorescence by absorbing excitation light emitted from an excitation light source, and a second phosphor that emits fluorescence having a peak wavelength different from that of the first phosphor; A color adjustment method for a light emitting device comprising
And a wavelength control step of changing a wavelength of the excitation light in a wavelength region where the absorption wavelength region of the first phosphor and the absorption wavelength region of the second phosphor overlap each other. Color adjustment method.

Images