JP5971148B2 - Fluorescent light source device - Google Patents

Description

  The present invention relates to a fluorescent light source device, and more particularly to a fluorescent light source device including a wavelength conversion member made of a phosphor excited by excitation light such as laser light.

Conventionally, as a green light source used in a projector device, a fluorescent light source device including a laser light source and a wavelength conversion member made of a phosphor excited by laser light from the laser light source is known (for example, a patent) Reference 1).
Specifically, in Patent Document 1, as shown in FIG. 7, as a green light source of a projector device, a laser light source 51 that emits laser light oscillating in a blue region, a fluorescent wheel 52, and the fluorescent wheel 52 are rotated. A fluorescent light source device including a wheel motor 53 is used. The fluorescent wheel 52 of the fluorescent light source device is formed by forming a wavelength conversion member layer made of a phosphor excited by the laser light on a base material that transmits the laser light from the laser light source 51.
In FIG. 7, 61 is a collimating lens, and 62 is a red light source composed of a red light emitting diode. Reference numerals 63A, 63B, 63C, 64A, 64B, and 64C denote condensing lenses. Reference numeral 65 denotes a dichroic mirror that transmits light from the green light source and reflects light from the red light source. Reference numeral 66 denotes a light guide device incident lens. Reference numeral 67 denotes a reflection mirror, and reference numeral 68 denotes a light guide device.

  However, there is a problem that the configuration of the drive system of the fluorescent wheel 52 including the wheel motor 53 is complicated, and a long service life cannot be obtained for the wheel motor 53 due to deterioration of the constituent members.

On the other hand, as a fluorescent light source device, a fixed type device having no rotation mechanism has been proposed (for example, see Patent Document 2).
Specifically, in Patent Document 2, as shown in FIG. 8, a wavelength conversion member 71 made of a phosphor (YAG sintered body) excited by laser light from a laser light source is made of barium sulfate on a substrate 72. There is disclosed a fluorescent light source device that is bonded via a thermal expansion absorption layer 73 and in which this bonded body is fixedly provided with respect to a laser light source.
In FIG. 8, 74 is a heat radiating plate made of metal, and 75 is a heat radiating heat sink.

  However, in such a fluorescent light source device, when the laser light is irradiated onto the wavelength conversion member 71 made of a YAG sintered body, the laser light is back-scattered on the surface of the wavelength conversion member 71. Is not sufficiently taken into the wavelength conversion member 71, and as a result, there is a problem that high luminous efficiency cannot be obtained.

JP 2011-13316 A JP 2011-198560 A

  The present invention has been made based on the above circumstances, and its purpose is to suppress backscattering of the excitation light when the wavelength conversion member is irradiated with the excitation light, and to convert the wavelength. An object of the present invention is to provide a fluorescent light source device that is excellent in the efficiency of taking out fluorescence from the inside of a member and as a result, can obtain high luminous efficiency.

The fluorescent light source device of the present invention is a fluorescent light source device comprising a wavelength conversion member by a phosphor excited by excitation light,
The excitation light receiving surface of the wavelength conversion member is formed with a periodic structure in which substantially cone-shaped projections are periodically arranged, and the period of the periodic structure causes diffraction of fluorescence emitted from the phosphor. Is the size of the range that occurs,
A light reflecting film made of a dielectric multilayer film is formed on the back surface of the wavelength conversion member.

  In the fluorescent light source device of the present invention, it is preferable that a peripheral side surface of the wavelength conversion member is surrounded by a reflection surface.

  In the fluorescent light source device of the present invention, it is preferable that the reflection surface surrounding the peripheral side surface of the wavelength conversion member is a diffuse reflection surface.

According to the fluorescent light source device of the present invention, basically, the excitation light receiving surface of the wavelength conversion member has a periodic structure in which substantially cone-shaped convex portions are periodically arranged. When excitation light is irradiated to the light, backscattering of the excitation light is suppressed, and as a result, high luminous efficiency is obtained.
In addition, since the period of the periodic structure formed on the excitation light receiving surface of the wavelength conversion member is within a range in which the diffraction of the fluorescence emitted from the phosphor is generated, the fluorescence emitted from the phosphor can be reduced. The light can be emitted to the outside with high efficiency, and as a result, higher luminous efficiency can be obtained.
And, since the light reflecting film made of the dielectric multilayer film is formed on the back surface of the wavelength conversion member, the fluorescence generated inside the wavelength conversion member can be taken out with high efficiency. High luminous efficiency can be obtained.

  Further, according to the fluorescent light source device having the configuration in which the peripheral side surface of the wavelength conversion member is surrounded by the reflection surface, the fluorescence emitted from the peripheral side surface of the wavelength conversion member is reflected by the reflection surface and the inside of the wavelength conversion member Thus, the fluorescence generated inside the wavelength conversion member can be extracted with higher efficiency.

  Further, according to the fluorescent light source device configured such that the reflection surface surrounding the peripheral side surface of the wavelength conversion member is a diffuse reflection surface, when the fluorescence emitted from the peripheral side surface of the wavelength conversion member is returned to the inside of the wavelength conversion member Since the direction is changed by diffuse reflection and the light is easily extracted in the front direction (excitation light receiving surface direction) of the wavelength conversion member, the fluorescence generated inside the wavelength conversion member can be extracted with higher efficiency.

It is explanatory drawing which shows the outline of a structure in an example of the fluorescence light source device of this invention. It is sectional drawing for description which shows the structure of the fluorescence light emission member in the fluorescence light source device shown in FIG. It is the figure which showed macroscopically the change of the refractive index of the medium which the said excitation light propagates when excitation light injects in the direction perpendicular | vertical to the surface of a fluorescent member, (a) is an enlarged view of a part of fluorescent member (B) is a graph showing a macroscopic relationship between the position in the direction perpendicular to the surface of the fluorescent member and the refractive index. It is explanatory drawing which shows typically the reflection and diffraction which arise in fluorescence on the surface of a fluorescent member. It is sectional drawing for description which shows the structure of the fluorescence light emission member in the other example of the fluorescence light source device of this invention. It is sectional drawing for description which shows the structure of the fluorescence light emission member in the further another example of the fluorescence light source device of this invention. It is explanatory drawing which shows an example of a structure of the conventional fluorescence light source device. It is explanatory drawing which shows the other example of a structure of the conventional fluorescence light source device.

Hereinafter, embodiments of the fluorescent light source device of the present invention will be described.
FIG. 1 is an explanatory diagram showing an outline of the configuration of an example of the fluorescent light source device of the present invention, and FIG. 2 is an explanatory sectional view showing the configuration of a fluorescent light emitting member in the fluorescent light source device shown in FIG.
As shown in FIG. 1, this fluorescent light source device includes a laser diode 10 that emits light in a blue region, and excitation that is laser light emitted from the laser diode 10 that is disposed opposite to the laser diode 10. And a fluorescent light emitting member 20 having a wavelength conversion member made of a fluorescent member 22 formed of a phosphor that is excited by light L and emits fluorescent light L1 in the green region.
A collimator lens 15 that emits the excitation light L incident from the laser diode 10 as a parallel light beam is disposed at a position close to the laser diode 10 between the laser diode 10 and the fluorescent light emitting member 20. A dichroic mirror 16 that transmits the excitation light L from the laser diode 10 and reflects the fluorescence L1 from the fluorescent light emitting member 20 is disposed between the collimator lens 15 and the fluorescent light emitting member 20. For example, it is arranged in a posture inclined at an angle of 45 °.
In FIG. 1, the light of one laser diode 10 is used. However, there are a plurality of laser diodes 10, a condensing lens is disposed in front of the fluorescent light emitting member 20, and the fluorescent light emitting member 20 is irradiated with the condensed light. It may be. In addition, the excitation light is not limited to the light from the laser diode 10, and may be one that collects the light from the LED as long as it can excite the phosphor in the fluorescent light emitting member 20, and further, mercury, Light from a lamp enclosing xenon or the like may be used. When a light source having a width in the emission wavelength such as a lamp or LED is used, the wavelength of the excitation light is the main emission wavelength region. However, the present invention is not limited to this.

As shown in FIG. 2, the fluorescent light emitting member 20 includes a rectangular substrate 21 and a wavelength conversion member made of, for example, a rectangular plate-like fluorescent member 22 provided on the surface of the substrate 21. In the fluorescent light emitting member 20 of this example, the surface of the wavelength conversion member (the upper surface in FIG. 2) is the excitation light receiving surface. The surface of the wavelength conversion member functions as an excitation light receiving surface and also functions as a light emitting surface. And the conical convex part 23a (refer FIG. 3) which becomes small diameter according to the direction which goes to a surface from a back surface on the excitation light light-receiving surface of a wavelength conversion member, ie, the surface of the fluorescent member 22 in this example, is periodically arranged. Thus formed periodic structure 23 (see FIG. 3) is formed. Moreover, the reflection member 28 is formed in the surrounding side surface of the wavelength conversion member so that the reflection surface may oppose the surrounding side surface. Further, for example, heat radiating fins (not shown) are arranged on the back surface of the substrate 21.
A light reflecting film 24 made of a dielectric multilayer film is formed on the back surface (lower surface in FIG. 2) of the wavelength conversion member (in this example, the fluorescent member 22).

  As a material constituting the substrate 21, an aluminum substrate or the like via a heat radiation adhesive in which metal fine powder is mixed into a resin can be used. Moreover, the thickness of the board | substrate 21 is 0.5-1.0 mm, for example. Further, the aluminum substrate may have a function of a heat radiating fin.

  The fluorescent member 22 is composed of a single crystal or polycrystalline phosphor. The thickness of the fluorescent member 22 is, for example, 0.05 to 2.0 mm.

The single crystal phosphor constituting the fluorescent member 22 can be obtained, for example, by the Czochralski method. Specifically, the seed crystal is brought into contact with the melted raw material in the crucible, and in this state, the seed crystal is pulled up in the vertical direction while rotating the seed crystal to grow the single crystal on the seed crystal. The body is obtained.
Moreover, the polycrystalline fluorescent substance which comprises the fluorescent member 22 can be obtained as follows, for example. First, raw materials such as a base material, an activator, and a firing aid are pulverized by a ball mill or the like to obtain raw material fine particles of submicron or less. Next, the raw material fine particles are sintered by, for example, a slip casting method. Thereafter, a polycrystalline phosphor having a porosity of 0.5% or less, for example, is obtained by subjecting the obtained sintered body to hot isostatic pressing.

  Specific examples of the phosphor constituting the fluorescent member 22 include YAG: Ce, YAG: Pr, YAG: Sm, and LuAG: Ce. In such a phosphor, the rare earth element doping amount is about 0.5 mol%.

The periodic structure 23 formed on the surface of the fluorescent member 22 has a configuration in which substantially cone-shaped convex portions 23a (see FIG. 3) having a small diameter in a direction from the back surface to the surface are periodically arranged.
In the present invention, the period of the periodic structure means a distance (nm) between convex portions adjacent to each other in the periodic structure.
As described above, the periodic structure 23 is formed on the excitation light receiving surface of the wavelength conversion member (in this example, the surface of the fluorescent member 22), thereby preventing the excitation light L from being reflected on the surface of the fluorescent member 22. Or it can be suppressed. Such an action occurs for the following reason.
FIG. 3 is a macroscopic view showing a change in the refractive index of the medium through which the excitation light L propagates when the excitation light L is incident in a direction perpendicular to the surface of the fluorescent member 22. FIG. It is sectional drawing which expands and shows a part of fluorescent member 22, (b) is a graph which shows the macro relationship between the position in a direction perpendicular | vertical with respect to the surface of the fluorescent member 22, and a refractive index. As shown in FIG. 3, when the excitation light L is irradiated from the air (refractive index is 1) onto the surface of the fluorescent member 22 (refractive index is N ₁ ), the conical structure 23 constituting the periodic structure 23 is formed. Since the light is incident from a direction inclined with respect to the tapered surface of the convex portion 23a, when viewed macroscopically, the refractive index of the medium through which the excitation light L propagates starts from 1 in a direction perpendicular to the surface of the fluorescent member 22. It will gradually change to N ₁ . Therefore, since there is substantially no interface on the surface of the fluorescent member 22 where the refractive index changes rapidly, it is possible to prevent or suppress the excitation light L from being reflected on the surface of the fluorescent member 22.
On the other hand, when the periodic structure 23 is not formed, the inclined surface is regarded as a boundary surface between two media having different refractive indexes, so that reflected light is generated according to the refractive index difference.

The period d of the periodic structure 23 is set to the size of the range (Bragg's condition) where diffraction of the fluorescence L1 emitted from the phosphor constituting the fluorescent member 22 occurs. Specifically, the period d of the periodic structure 23 indicates the peak wavelength of the fluorescence L1 emitted from the phosphor, and the refractive index of the material constituting the periodic structure 23 (the phosphor constituting the fluorescent member 22 in the illustrated example). The value divided by (hereinafter referred to as “optical length”) or a value in the vicinity of the optical length.
By satisfying this condition, the fluorescence L1 emitted from the phosphor constituting the fluorescent member 22 can be emitted from the surface of the fluorescent member 22 to the outside with high efficiency. More specifically, as shown in FIG. 4, when the incident angle θI of the fluorescence L1 generated in the fluorescent member 22 with respect to the surface of the fluorescent member 22 (interface between the fluorescent member 22 and air) is less than the critical angle. Is extracted from the surface of the fluorescent member 22 to the outside without reflection as transmitted light L2 that passes through the surface of the fluorescent member 22. Further, when the incident angle θI of the fluorescence L1 with respect to the surface of the fluorescent member 22 is equal to or larger than the critical angle, for example, when the surface of the fluorescent member 22 is a flat surface, the fluorescent L1 is totally reflected on the surface of the fluorescent member 22. Therefore, the reflected light L3 goes to the inside of the fluorescent member 22 and cannot be taken out from the surface of the fluorescent member 22. However, when the periodic structure 23 having the period d that satisfies the above condition is formed on the surface of the fluorescent member 22, the fluorescence L <b> 1 is diffracted by the periodic structure 23 on the surface of the fluorescent member 22. As a result, the -1st-order diffracted light L4 is emitted from the surface of the fluorescent member 22 at an emission angle θm (θm <θI) and extracted outside.

  Further, the ratio [h / d] (aspect ratio) of the height h of the convex portion 23a to the period d in the periodic structure 23 is 0.2 or more, preferably 0.2 to 1.5, and particularly preferably. Is 0.5 to 1.0. When the aspect ratio [h / d] is less than 0.2, the diffraction region in the height direction becomes narrow, and sufficient light extraction efficiency by diffraction cannot be obtained.

  Such a periodic structure 23 can be formed by a nanoimprint method and a dry etching process. Specifically, a resist is applied to the surface of the fluorescent member 22 by, for example, a spin coat method, and then a resist coating film is patterned by, for example, a nanoimprint method. Thereafter, the exposed structure on the surface of the fluorescent member 22 is dry-etched to form the periodic structure 23.

The light reflecting film 24 formed on the back surface of the fluorescent member 22 is made of a dielectric multilayer film.
Specifically, it has a two-layer structure of Ag + increased reflection protective film (SiO ₂ or Al ₂ O ₃ ), a structure in which silica (SiO ₂ ) layers and titania (TiO ₂ ) layers are alternately laminated, or nitriding An aluminum (AlN) layer and an aluminum oxide (Al ₂ O ₃ ) layer are alternately laminated. Examples of the material for the layers constituting the dielectric multilayer film include AlN, SiO ₂ , SiN, and ZrO _2. , SiO, TiO ₂ , Ta ₂ O ₃ , Nb ₂ O _{5 and the} like.
For example, in a dielectric multilayer film of a combination of SiO ₂ / Ta ₂ O ₃ , SiO ₂ / Nb ₂ O ₅ , SiO ₂ / TiO ₂ , the refractive indexes of TiO ₂ , Nb ₂ O ₅ and Ta ₂ O ₃ are is in the order of _{TiO 2> Nb 2 O 5>} Ta 2 O 3, the total thickness of the SiO ₂ becomes thinner when the dielectric multilayer film of a combination of SiO ₂ / TiO _2. For this reason, the thermal resistance of the dielectric multilayer film is lowered and the heat conduction is improved.
For this reason, it is preferable to use an aluminum nitride (AlN) layer and an aluminum oxide (Al ₂ O ₃ ) layer that are alternately stacked. When a dielectric multilayer film in which aluminum nitride (AlN) layers and aluminum oxide (Al ₂ O ₃ ) layers are alternately stacked is used, the thermal conductivity of the dielectric multilayer film is further improved. For this reason, the temperature rise of the wavelength conversion member can be suppressed, and accordingly, the light amount decrease due to the temperature quenching can be suppressed.

Since the light reflecting film 24 made of the dielectric multilayer film is formed on the back surface of the wavelength conversion member, the dielectric multilayer film has a higher reflectance than the silver single layer film. Compared with the case where it consists of a single layer film of silver, the fluorescence generated inside the wavelength conversion member can be extracted with high efficiency.
In addition, the dielectric multilayer film is not affected by sulfidation or oxidation as compared with a silver single layer film, and therefore does not require a protective film made of SiO ₂ or the like. For this reason, it becomes possible to take a simple structure and high weather resistance is obtained. Therefore, it is possible to prevent the efficiency of extracting the fluorescence generated inside the wavelength conversion member from decreasing.

For example, when the light reflecting film 24 is made of a dielectric multilayer film of a combination of SiO ₂ / TiO ₂ , the total number is 69 layers, and the total thickness of the layers made of SiO ₂ is as follows. Is 3.3 μm, the total layer thickness of TiO ₂ is 1.8 μm, the thickness of the dielectric multilayer film is 5 μm, and the reflectance can be 98% or more in the wavelength range of 425 nm to 600 nm. .

Further, the fluorescent light emitting member 20 is formed by vapor deposition on the entire back surface (the lower surface in FIG. 2) of the light reflecting film 24 from the viewpoint of bonding property to the substrate 21, for example, Cr / Ni / Au = It is preferable that the bonding member layer 25 is formed through a vapor deposition film (not shown) such as 30 nm / 500 nm / 500 nm or Ti / Ni / Au = 30 nm / 500 nm / 500 nm. At this time, using Ti rather than Cr as the adhesion film with the light reflecting film 24 (dielectric multilayer film) improves the adhesion with the dielectric multilayer film.
The joining member layer 25 may be formed of solder, silver (Ag) sintered material, silver (Ag) epoxy adhesive, or the like. At this time, when the joining member layer 25 is made of solder, a film of Ti / Pt / Au = 30 nm / 500 nm / 500 nm is formed as a film in contact with the joining member layer 25 in the vapor deposition film. , Pt can further suppress the Sn diffusion of the solder, and as a result, the long-term reliability of the bonding member layer 25 can be ensured. Furthermore, when using solder with a higher melting point, Ti / Pt may be laminated, and Au may be laminated as the final film.

  In the fluorescent light emitting member 20, the reflection member 28 is formed on the peripheral side surface of the wavelength conversion member so that the reflection surface 28a faces the peripheral side surface, and in particular, the reflection surface 28a is a diffuse reflection surface. It is preferable.

In the present invention, the reflection member may be formed in contact with the wavelength conversion member, or may be formed in a state separated from the peripheral side surface of the wavelength conversion member, as shown in FIG. In FIG. 5, the reflecting member is denoted by reference numeral 38.
The reflecting member preferably has at least the same height as the wavelength conversion member (see FIG. 5), but may be configured higher than the wavelength conversion member as shown in FIG. By setting it as such a structure, a laser beam can be reliably irradiated to the excitation light light-receiving surface of a wavelength conversion member. In FIG. 6, the reflecting member is denoted by reference numeral 48.

As the reflecting member when the reflecting surface 28a is a specular reflecting surface, for example, a cylindrical specular reflecting member can be used. As the cylindrical specular reflection member, an inner peripheral surface of a cylindrical glass having a thin film made of silver, a high-luminance aluminum plate, an Ag + intensity reflection protective film (SiO ₂ or Al ₂ O ₃ ), the surface of an aluminum plate For example, a plurality of reflectors, such as a dielectric multilayer film formed thereon, may be combined in a square tube shape and bonded with an adhesive such as an epoxy resin.
These cylindrical mirror reflecting members can be fixed on the substrate 21 by an adhesive layer 26 made of silicone resin, epoxy resin, ceramic or the like.
The adhesive layer 26 for fixing the cylindrical specular reflection member may be formed from the material of the reflection member 28 described below. When the cylindrical specular reflection member is fixed with such a reflective material, the fluorescence incident on the adhesive layer 26 is also diffusely reflected, and the fluorescence can be extracted with high efficiency. In addition, since the direction of light is changed even when the light reenters the wavelength conversion member, fluorescence can be extracted with high efficiency.

When the reflecting surface 28a is a diffuse reflecting surface, the reflecting member is cured by dispersing aluminum oxide (Al ₂ O ₃ ), titania (TiO ₂ ) or barium sulfate of several microns to nano order in silicone or glass paste. Or fired product.
In the case where the reflecting member is in contact with the wavelength conversion member, the material can be formed by curing or baking after coating the material in contact with the peripheral side surface of the wavelength conversion member.
Further, when the reflecting member is separated from the wavelength converting member, it is cured or baked in a state where the above materials are separately formed in an appropriate shape, and a silicone resin, an epoxy resin, a ceramic, a low melting glass It can be formed by fixing on the substrate 21 with an adhesive layer 26 made of sol-gel or the like.

  The reflectance of the reflecting surface 28a is preferably 98% or more.

Since the reflection member 28 is provided so as to surround the peripheral side surface of the wavelength conversion member, the fluorescence emitted from the peripheral side surface of the wavelength conversion member is reflected by the reflection surface 28a and returned to the inside of the wavelength conversion member. Therefore, fluorescence generated inside the wavelength conversion member can be extracted with higher efficiency.
Further, since the reflection surface 28a is a diffuse reflection surface, the direction of the fluorescence emitted from the peripheral side surface of the wavelength conversion member is changed by diffuse reflection when returning to the inside of the wavelength conversion member, and the wavelength conversion member. Therefore, the fluorescence generated inside the wavelength conversion member can be extracted with higher efficiency.

In the fluorescent light source device described above, the excitation light L that is the laser light in the blue region emitted from the laser diode 10 is converted into a parallel light beam by the collimator lens 15. Thereafter, the excitation light L passes through the dichroic mirror 16 and is irradiated substantially perpendicularly to the excitation light receiving surface of the wavelength conversion member, that is, the surface of the fluorescent member 22. And in the fluorescent member 22, the fluorescent substance which comprises the said fluorescent member 22 is excited, and fluorescence L1 is radiated | emitted. The fluorescence L1 is emitted from the surface of the fluorescent member 22, reflected by the dichroic mirror 16 in the vertical direction, and then emitted to the outside of the fluorescent light source device.
In addition, although the laser beam radiated | emitted from the laser diode 10 was used as excitation light of this embodiment, excitation light is not restricted to the light of the laser diode 10, What is necessary is just what can excite a fluorescent substance. For example, LED light may be collected, or light from a discharge lamp in which mercury, xenon gas, or the like is sealed may be used.

In such a fluorescent light source device, the periodic structure 23 is basically formed on the surface of the fluorescent member 22 that is the excitation light receiving surface of the wavelength conversion member. For this reason, when the excitation light L is irradiated to the excitation light receiving surface of the wavelength conversion member, backscattering of the excitation light L is suppressed, and as a result, high luminous efficiency is obtained.
Further, the period d of the periodic structure 23 is set to the size of the range in which diffraction of the fluorescence L1 emitted from the phosphor L1 constituting the fluorescent member 22 occurs. Thereby, the fluorescence L1 emitted from the phosphor can be taken out with high efficiency, and as a result, higher luminous efficiency can be obtained.
Since the light reflecting film 24 made of a dielectric multilayer film is formed on the back surface of the fluorescent member 22, the fluorescence generated inside the fluorescent material can be taken out with high efficiency. High luminous efficiency can be obtained.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made.
For example, the wavelength conversion member is not limited to being formed only of a fluorescent member, and the wavelength conversion member is formed on the surface of a plate-like fluorescent member on which the periodic structure is not formed. The periodic structure layers thus formed may be laminated. In the fluorescent light emitting member of such an example, the surface of the periodic structure layer is the excitation light receiving surface.
The periodic structure formed on the surface of the periodic structure layer may have the same shape as the periodic structure 23 formed on the surface of the fluorescent member 22 in the fluorescent light source device shown in FIG.
As a material constituting the periodic structure layer, a material having a refractive index higher than that of the fluorescent member is preferably used. By configuring the periodic structure layer with such a material, when the fluorescence is incident on the periodic structure layer from the fluorescent member, the angle of the fluorescence in the periodic structure layer becomes smaller than the incident angle, and the emission surface Since it approaches the normal direction, the fluorescence is more easily extracted.
The configuration of the substrate, the fluorescent member, the light reflecting film, the bonding member layer, and the reflecting member is the same as that of the fluorescent light source device shown in FIG. 1 except that the periodic structure is not directly formed on the surface of the fluorescent member.

  Moreover, the structure of the whole fluorescence light source device is not limited to what is shown in FIG. 1, A various structure is employable.

  Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto.

[Example 1]
According to the configuration shown in FIG. 2, a fluorescent light-emitting member [A1] having the following specifications was produced.
[Substrate (21)]
Material: Aluminum substrate, Dimensions: 25 mm (length) x 25 mm (width) x 1 mm (thickness)
[Fluorescent member (22)]
Material: LuAG Refractive index = 1.83, excitation wavelength = 445 nm, fluorescence wavelength = 535 nm), dimensions: 1.7 mm (length) × 3.0 mm (width) × 130 μm (thickness)
[Periodic structure (23)]
Convex part (23a) shape: conical, period (d) = 600 nm, convex part (26a) height (h) = 600 nm (aspect ratio [h / d] = 1.0)
[Light Reflecting Film (24)]
Material: Dielectric multilayer film of a combination of SiO ₂ / TiO ₂ , total 69 layers (total thickness of SiO ₂ layer 3.3 μm, total thickness of TiO ₂ layer 1.8 μm) Reflectance in the wavelength range of 425 nm to 600 nm 99% or more.

[Example 2]
In Example 1, a fluorescent light emitting member [A2] having the same configuration and specifications as the fluorescent light emitting member [A1] was prepared except that the reflectance of the dielectric multilayer film was set to 98%.

[Comparative Example 1]
In Example 1, a fluorescent light-emitting member [B1] having the same configuration and specifications as the fluorescent light-emitting member [A1] was prepared except that the light-reflecting film on the back surface was a single-layer film of 96% reflectance. did.

[Comparative Example 2]
In Comparative Example 1, a fluorescent light emitting member having the same configuration and specifications as the fluorescent light emitting member [B1] except that the light reflecting film on the back surface is a single layer film of Ag / Pd / Cu alloy having a reflectance of 94% [B2] was produced.

  Excitation light having a peak wavelength of 445 nm is irradiated on each of the excitation light receiving surfaces (surfaces of the fluorescence member) of the fluorescent light emitting members [A1], [A2], [B1], and [B2]. The reflectance and the fluorescence extraction efficiency from the fluorescent member were measured. The results are shown in Table 1.

  From the above results, when the light reflecting film formed on the back surface of the fluorescent member is made of a dielectric multilayer film, the light from the fluorescent member is compared with the case where the light reflecting film made of silver is formed. It was confirmed that the extraction efficiency can be increased.

DESCRIPTION OF SYMBOLS 10 Laser diode 15 Collimator lens 16 Dichroic mirror 20 Fluorescent light emitting member 21 Substrate 22 Fluorescent member 23 Periodic structure 23a Protruding part 24 Light reflecting film 25 Bonding member layer 26 Adhesive layers 28, 38, 48 Reflecting member 28a Reflecting surface L Excitation light L1 Fluorescence L2 Transmitted light L3 Reflected light L4 First-order diffracted light 51 Laser light source 52 Fluorescent wheel 53 Wheel motor 61 Collimating lens 62 Red light source 63A, 63B, 63C, 64A, 64B, 64C Condensing lens 65 Dichroic mirror 66 Light guide device incident lens 67 Reflective mirror 68 Light guide device 71 Wavelength conversion member 72 Substrate 73 Thermal expansion absorption layer 74 Heat radiation plate 75 Heat radiation heat sink

Claims (3)

A fluorescent light source device comprising a wavelength conversion member made of a phosphor excited by excitation light,
The excitation light receiving surface of the wavelength conversion member is formed with a periodic structure in which substantially cone-shaped projections are periodically arranged, and the period of the periodic structure causes diffraction of fluorescence emitted from the phosphor. Is the size of the range that occurs,
A fluorescent light source device, wherein a light reflection film made of a dielectric multilayer film is formed on the back surface of the wavelength conversion member.   The fluorescent light source device according to claim 1, wherein a peripheral side surface of the wavelength conversion member is surrounded by a reflection surface. The fluorescent light source device according to claim 2, wherein the reflection surface surrounding the peripheral side surface of the wavelength conversion member is a diffuse reflection surface.

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