JP2014153527A - Fluorescent light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescent light source device that, when a wavelength changing member is irradiated with exciting light, not only restrains backward scattering of the exciting light but also externally emits at high efficiency fluorescent light generated within the wavelength changing member, and therefore can achieve high luminous efficiency.SOLUTION: A fluorescent light source device is provided with a wavelength changing member, consisting of a fluorescent substance excited by exciting light; the wavelength changing member has a front face side periodic structure formed on its front face, which is supposed to be the exciting light receiving face, and a rear face side periodic structure on the rear face, on whose outside a light reflecting face is disposed.

Description

  The present invention relates to a fluorescent light source device that emits fluorescence from a phosphor by exciting the phosphor with excitation light.

For example, as a green light source used in a projector, a fluorescent light source device that emits green light from the phosphor by irradiating the phosphor with laser light is conventionally known. As an example of such a fluorescent light source device, a wavelength conversion member in which a phosphor is coated on the surface of a rotating wheel is provided, and the wavelength conversion is performed by irradiating the wavelength conversion member with laser light in a blue region. A fluorescent light source device that generates light in a green region in a phosphor in a member is known (see Patent Document 1).
However, in the fluorescent light source device using the wavelength conversion member provided with the rotating wheel, the motor part that rotationally drives the rotating wheel is likely to be deteriorated and troubled, and the configuration of the drive system itself is complicated. There is a problem.

As another example of the fluorescent light source device, for example, as shown in FIG. 9, the YAG is formed on the surface of the substrate 62 made of an AIN sintered body having the heat radiation fins 64 provided on the back surface through the barium sulfate layer 63. In the fluorescent member 61, a fluorescent member 61 made of a sintered body is provided, and the fluorescent member 61 in the wavelength converting member is irradiated with laser light in a blue region as excitation light. A fluorescent light source device that generates light in a green region is known (see Patent Document 2).
However, such a fluorescent light source device has a problem that high luminous efficiency cannot be obtained.
Specifically, when the excitation light is irradiated onto the fluorescent member 61, the excitation light is back-scattered on the surface of the fluorescent member 61, so that the excitation light is not sufficiently taken into the fluorescent member 61. There's a problem. In addition, among the fluorescence generated by the phosphor in the fluorescent member 61, the fluorescent light whose incident angle with respect to the interface between the fluorescent member 61 and the air exceeds the critical angle is confined in the fluorescent member 61, so that the fluorescent light is efficiently used. There is a problem that you can not.

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 can emit fluorescence generated inside a member to the outside with high efficiency, and thus 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 wavelength conversion member has a surface-side periodic structure formed on a surface that is an excitation light receiving surface, a back-side periodic structure is formed on the back surface, and a light reflecting surface is provided outside the back surface. Features.

  In the fluorescent light source device of the present invention, it is preferable that the period of the surface-side periodic structure is a size within a range where diffraction of fluorescence emitted from the phosphor occurs.

  In the fluorescent light source device of the present invention, it is preferable that the period of the back-side periodic structure has a size within a range where diffraction of fluorescence emitted from the phosphor occurs.

  In the fluorescent light source device of the present invention, it is preferable that the wavelength conversion member is entirely made of a fluorescent member containing a phosphor.

In the fluorescent light source device of the present invention, the wavelength conversion member includes a fluorescent member containing a phosphor, a surface-side periodic structure layer having a periodic structure on the surface, formed on the surface of the fluorescent member, And at least one periodic structure layer of the back-side periodic structure layer having a periodic structure on the back surface, preferably formed on the back surface of the fluorescent member.
In the fluorescent light source device of the present invention having such a configuration, the refractive index of the periodic structure layer formed on the fluorescent member is preferably equal to or higher than the refractive index of the fluorescent member.

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 wavelength conversion member has a surface-side periodic structure formed on the surface to be an excitation light receiving surface, a back surface is a light diffusion surface formed by a rough surface, and a light reflection surface is provided outside the back surface. It is characterized by.

In the fluorescent light source device of the present invention, since the surface-side periodic structure is formed on the excitation light receiving surface of the wavelength conversion member, the backscattering of the excitation light is suppressed when the wavelength conversion member is irradiated with the excitation light. As a result, the excitation light can be sufficiently taken into the wavelength conversion member.
In addition, a light reflecting surface is provided outside the back surface of the wavelength conversion member, and the back surface is provided with a back surface-side periodic structure, or a light diffusing surface is formed by a rough surface. It is said that. For this reason, the fluorescence emitted from the phosphor inside the wavelength conversion member is reflected on the light reflection surface at a different angle on the back surface, so that the fluorescence is prevented from being confined inside the wavelength conversion member.
Therefore, according to the fluorescence light source device of the present invention, the excitation light can be sufficiently taken into the wavelength conversion member, and the fluorescence generated in the wavelength conversion member can be emitted to the outside with high efficiency. High luminous efficiency can be obtained.

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 wavelength conversion member in the fluorescence light source device of FIG. It is explanatory drawing which shows typically the modification of the surface side periodic structure in a wavelength conversion member. 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 the wavelength conversion member which consists of fluorescent members, (a) is wavelength conversion It is sectional drawing which expands and shows a part of member, (b) is a graph which shows the macro relationship of the position and refractive index in the direction perpendicular | vertical with respect to the surface of a wavelength conversion member. It is sectional drawing for description which shows the structure of the wavelength conversion 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 wavelength conversion member in the further another example of the fluorescence light source device of this invention. It is sectional drawing for description which shows the structure of the wavelength conversion member in the further another example of the fluorescence light source device of this invention. It is a graph which shows the relationship between the reflectance of the light in the back surface of the wavelength conversion member obtained in Experimental example 2, and the light extraction efficiency of the said wavelength conversion member. It is sectional drawing for description which shows the structure of the wavelength conversion member in the conventional fluorescence light source device.

  Hereinafter, embodiments of the fluorescent light source device of the present invention will be described.

(First embodiment)
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 wavelength conversion member in the fluorescent light source device of FIG.
As shown in FIG. 1, the 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 that is excited by the light L and emits the 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 wavelength conversion member in the fluorescent light emitting member 20 is provided 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 ° with respect to the 15 optical axes.
Here, in FIG. 1, the light of one laser diode 10 is used, but there are a plurality of laser diodes 10, a condenser lens is disposed in front of the wavelength conversion member in the fluorescent light emitting member 20, and the condensed light is The form which irradiates a wavelength conversion member may be sufficient. Further, 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 wavelength conversion member, and further, mercury or xenon. The light from the lamp in which etc. were enclosed may be sufficient. 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 is provided with a wavelength conversion member made of a substantially rectangular plate-like fluorescent member 21 on the surface of a rectangular substrate 31 (upper surface in FIG. 2).
The fluorescent light emitting member 20 is arranged so that the surface (the upper surface in FIG. 2) of the fluorescent member 21 faces the laser diode 10, and the surface is an excitation light receiving surface and a fluorescent light emitting surface. ing.
Further, a light reflecting film 33 made of, for example, silver is provided on each of the back surface (lower surface in FIG. 2) and side surfaces of the fluorescent member 21. As described above, the light reflecting film 33 is formed on the back surface and the side surface of the fluorescent member 21, so that the light reflecting surface is provided outside the back surface and the side surface of the fluorescent member 21. Further, on the back surface of the substrate 31, for example, heat radiation fins (not shown) are arranged.

In the fluorescent member 21 constituting the wavelength conversion member, convex portions (hereinafter also referred to as “surface-side convex portions”) 23 are periodically arranged on the excitation light receiving surface, that is, the surface of the fluorescent member 21. A surface-side periodic structure 22 is formed. Further, on the back surface of the wavelength conversion member, that is, on the back surface of the fluorescent member 21, a back surface side periodic structure 25 in which convex portions (hereinafter also referred to as “back surface side convex portions”) 26 are periodically arranged is formed. .
Here, in this specification, the “periodic structure” means that periodic structures (convex portions 23 and 26 in FIG. 2) having a convex shape having a smaller diameter from the front surface to the back surface are periodically arranged. The resulting structure is shown.

  The fluorescent member 21 is composed of a single crystal or polycrystalline phosphor. The thickness of the fluorescent member 21 is, for example, 0.05 to 2.0 mm.

The single crystal phosphor constituting the fluorescent member 21 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 21 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 21 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%.

As shown in FIG. 2, it is preferable that the surface side convex part 23 which comprises the surface side periodic structure 22 formed in the surface of the fluorescent member 21 is a substantially cone shape.
Specifically, the substantially conical shape related to the surface-side convex portion 23 is a weight shape as shown in FIG. 2 (conical shape in FIG. 2) or a frustum shape as shown in FIG. 3 (conical shape in FIG. 3). State). Here, when the shape of the surface-side convex part 23 is a frustum shape, the dimension (maximum dimension) a of the upper bottom part 24a is less than the wavelength of the excitation light L. For example, when the shape of the convex portion 24 is a truncated cone shape and the wavelength of the excitation light L is 445 nm, the dimension (outer diameter) of the upper bottom portion 24a of the convex portion 24 having the truncated cone shape is 100 nm.

By making the shape of the surface side convex part 23 into a substantially pyramid shape, it is possible to prevent or suppress the excitation light L from being reflected on the surface of the fluorescent member 21. Such an action occurs for the following reason.
FIG. 4 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 21. FIG. It is sectional drawing which expands and shows typically a part of fluorescent member 21, (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 21, and a refractive index. . As shown in FIG. 4, when the excitation light L is irradiated from the air (refractive index is 1) onto the surface of the fluorescent member 21 (refractive index is N ₁ ), the surface constituting the surface-side periodic structure 22 The light is incident from a direction inclined with respect to the tapered surface of the side convex portion 23. Therefore, when viewed macroscopically, the refractive index of the medium through which the excitation light L propagates gradually changes from 1 to N ₁ in the direction perpendicular to the surface of the fluorescent member 21. Therefore, since the surface of the fluorescent member 21 has substantially no interface 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 21.

Moreover, in the substantially cone-shaped surface side convex part 23 which comprises the surface side periodic structure 22, it is preferable that the inclination angle (angle formed by a side surface and a bottom face) of a taper surface (side surface) is 11 degrees or more.
When the inclination angle of the taper surface is less than 11 °, the taper surface is regarded as a boundary surface between two media having different refractive indexes, and thus there is a possibility that reflected light is generated according to the difference in refractive index. is there.

In the surface-side periodic structure 22, the period d <b> 1 is preferably in a range (Bragg condition) in which diffraction of the fluorescence L <b> 1 emitted from the phosphor constituting the fluorescent member 21 occurs.
Specifically, the period d1 of the surface-side periodic structure 22 indicates the peak wavelength of the fluorescence L1 emitted from the phosphor, and the material constituting the surface-side periodic structure 22 (the phosphor constituting the fluorescent member 21 in FIG. 2). ) Divided by the refractive index (hereinafter referred to as “optical length”) or a value that is several times the optical length.
In the present invention, the period of the periodic structure means a distance (center distance) (nm) between convex portions adjacent to each other in the periodic structure.

By setting the period d1 of the surface-side periodic structure 22 to be in a range in which the diffraction of the fluorescence L1 generated in the fluorescent member 21 is generated, the fluorescence L1 can be emitted from the surface of the fluorescent member 21 to the outside with high efficiency. .
More specifically, the fluorescence L1 generated in the fluorescent member 21 is the surface of the fluorescent member 21 when the incident angle with respect to the surface of the fluorescent member 21 (interface between the fluorescent member 21 and air) is less than the critical angle. As a transmitted light that passes through the fluorescent member 21, the light is taken out from the surface of the fluorescent member 21 without reflection. Further, when the incident angle of the fluorescence L1 with respect to the surface of the fluorescent member 21 is equal to or larger than the critical angle, for example, when the surface of the fluorescent member is a flat surface, the fluorescence is totally reflected on the surface of the fluorescent member and wavelength conversion is performed. Since it goes to the inside of the member, it cannot be taken out from the surface of the fluorescent member. However, when the surface-side periodic structure 22 having the period d1 that satisfies the above conditions is formed on the surface of the fluorescent member 21, the fluorescence L1 is diffracted by the surface-side periodic structure 22 on the surface of the fluorescent member 21. It becomes. As a result, the -1st order diffracted light is emitted from the surface of the fluorescent member 21 and taken out to the outside.

Moreover, it is preferable that the aspect ratio which is ratio (h1 / d1) of the height h1 of the surface side convex part 23 with respect to the period d1 in the surface side periodic structure 22 is 0.2 or more.
When this ratio (h1 / d1) is less than 0.2, the diffraction region in the height direction becomes narrow, so that sufficient light extraction efficiency by diffraction cannot be obtained.

  Such a surface-side periodic structure 22 can be formed by a nanoimprint method and a dry etching process. Specifically, a resist is applied to the surface of the fluorescent member having a flat surface by, for example, spin coating, and then the resist coating film is patterned by, for example, nanoimprinting. Then, the surface side periodic structure 21 is formed by performing the dry etching process to the exposed area | region in the surface of a fluorescent member.

  The back surface side convex part 26 which comprises the back surface side periodic structure 25 formed in the surface of the fluorescent member 21 is cone shape.

Moreover, it is preferable that the period d2 of the back surface side periodic structure 25 is a size of a range (Bragg condition) in which diffraction of the fluorescence L1 emitted from the phosphor constituting the fluorescent member 21 occurs.
Specifically, the period d2 of the back-side periodic structure 25 indicates the peak wavelength of the fluorescence L1 emitted from the phosphor, and the material constituting the back-side periodic structure 25 (the phosphor constituting the fluorescent member 21 in FIG. 2). ) Divided by the refractive index (optical length), or a value several times the optical length.
By satisfying this condition, in the fluorescence L1 that occurs in the fluorescent member 21 and is incident on the surface of the fluorescent member 21, the amount of the fluorescent L1 whose incident angle is less than the critical angle can be increased. Therefore, the fluorescence L1 generated in the fluorescent member 21 can be emitted from the surface of the fluorescent member 21 to the outside with high efficiency.
More specifically, the fluorescence L1 that occurs in the fluorescent member 21 and has an incident angle with respect to the back surface (the interface between the fluorescent member 21 and the light reflecting film 33) of the fluorescent member 21 is greater than or equal to the critical angle. By forming the back surface side periodic structure 25 having the period d2 that satisfies the above-mentioned conditions on the back surface, diffraction is generated by the back surface side periodic structure 25 on the back surface. The −1st-order diffracted light is reflected toward the surface of the fluorescent member 21 by the light reflecting film 33 on the back surface of the fluorescent member 21 so as to be along the normal direction (perpendicular to the surface of the fluorescent member 21). Thus, since the minus first-order diffracted light of the fluorescence L1 generated by diffraction by the back-side periodic structure 25 is incident on the surface of the fluorescent member 21 so that the incident angle is less than the critical angle, the fluorescent member 21 In the fluorescence L1 incident on the surface, the amount of the fluorescence L1 whose incident angle is less than the critical angle becomes large.

  Such a back-side periodic structure 25 can be formed by a nanoimprint method and a dry etching process, similarly to the front-side periodic structure 22. Specifically, a resist is applied to the back surface of the fluorescent member having a flat back surface by, for example, spin coating, and then the resist coating film is patterned by, for example, nanoimprinting. Then, the back surface side periodic structure 25 is formed by performing the dry etching process to the exposed area | region in the back surface of a fluorescent member.

  As a material constituting the substrate 31, an aluminum substrate or the like through a heat radiation adhesive in which metal fine powder is mixed into a resin can be used. Moreover, the thickness of the board | substrate 31 is 0.5-1.0 mm, for example. Further, the aluminum substrate may have a function of a heat radiating fin.

  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 in the fluorescent light emitting member 20, that is, the surface of the fluorescent member 21. And in the fluorescent member 21, the fluorescent substance which comprises the said fluorescent member 21 is excited, and fluorescence L1 is radiated | emitted. The fluorescence L1 is emitted from the fluorescence emission surface of the wavelength conversion member, that is, the surface of the fluorescence member 21, reflected in the vertical direction by the dichroic mirror 16, and then emitted to the outside of the fluorescence light source device.

In this fluorescent light source device, the surface-side periodic structure 22 is formed on the surface of the fluorescent member 21 that is the excitation light receiving surface of the wavelength conversion member. For this reason, when the surface of the fluorescent member 21 is irradiated with the excitation light L, backscattering of the excitation light L is suppressed, and as a result, the excitation light L can be taken into the fluorescent member 21 with high efficiency.
In addition, a back side periodic structure 25 is formed on the back side of the fluorescent member 21 on which the light reflecting film 33 is provided. Therefore, the fluorescence L1 emitted from the phosphor in the fluorescent member 21 and incident on the back surface of the fluorescent member 21 is reflected at a different angle on the back surface. Therefore, the directivity of the fluorescence L1 that is repeatedly reflected in the fluorescent member 21 can be set to a direction perpendicular to the surface of the fluorescent member 21 that is the fluorescent emission surface of the wavelength conversion member. As a result, since the fluorescence L1 is suppressed from being confined in the fluorescence member 21, the fluorescence L1 can be extracted from the surface of the fluorescence member 21 to the outside with high efficiency.
In addition, since the period d1 of the front-side periodic structure 21 and the period d2 of the back-side periodic structure 25 are set to a size in which the diffraction of the fluorescence L1 generated in the fluorescent member 21 is generated, the fluorescence can be more efficiently generated. L1 can be taken out from the surface of the fluorescent member 21.
Therefore, according to this fluorescent light source device, the excitation light L can be sufficiently taken into the wavelength conversion member, and the fluorescence L1 generated inside the wavelength conversion member can be emitted to the outside with high efficiency. High luminous efficiency can be obtained.

(Second Embodiment)
FIG. 5 is a cross-sectional view illustrating the configuration of the wavelength conversion member in another example of the fluorescent light source device of the present invention.
In this fluorescent light source device, the wavelength conversion member 40 constituting the fluorescent light emitting member 20 is provided on a rectangular substrate 31 as shown in FIG. The wavelength converting member 40 includes a rectangular plate-like fluorescent member 41, a surface-side periodic structure layer 42 formed on the surface of the fluorescent member 41 (upper surface in FIG. 5), and the back surface of the fluorescent member 41 (FIG. 5). And a back-side periodic structure layer 44 formed on the lower surface. A surface-side periodic structure 43 is formed on the surface of the surface-side periodic structure layer 42, and the surface-side periodic structure 43 has conical convex portions (surface-side convex portions) 43 a periodically arranged. It will be. The back-side periodic structure layer 44 has a back-side periodic structure 45 formed on the back side, and the back-side periodic structure 45 has periodically arranged conical convex portions (back-side convex portions) 45a. It has been made.
In the wavelength conversion member 40, the surface (the upper surface in FIG. 5) of the surface-side periodic structure layer 42 is an excitation light receiving surface and a fluorescence emitting surface.
Further, a light reflecting film 33 made of, for example, silver is provided on each of the side surface of the fluorescent member 41, the back surface (the lower surface in FIG. 5), and the side surface of the back-side periodic structure layer 44. As described above, the light reflecting film 33 is formed on the side surface of the fluorescent member 41, the back surface and the side surface of the back surface side periodic structure layer 44, thereby providing a light reflecting surface on the outside of the back surface and the side surface of the wavelength conversion member 40. ing. Further, on the back surface of the substrate 31, for example, heat radiation fins (not shown) are arranged. The configurations of the substrate 31 and the fluorescent member 41 are the same as those of the fluorescent light source device of FIG. 1 except that the periodic structure is not directly formed on the front and back surfaces of the fluorescent member 41.

The surface side convex part 43a which comprises the surface side periodic structure 43 formed in the surface of the surface side periodic structure layer 42 is substantially the same as the surface side periodic structure 22 in the wavelength conversion member 20 of the fluorescence light source device of FIG. A conical shape is preferred. By making the shape of the front-side convex portion 43a into a substantially weight shape, the excitation light L can be taken into the wavelength conversion member 20 with higher efficiency.
In the surface-side periodic structure 43 formed on the surface of the surface-side periodic structure layer 42, the period d1 has a size within a range where diffraction of fluorescence emitted from the phosphor constituting the fluorescent member 41 occurs. Is preferred. By satisfying such conditions, the fluorescence emitted from the phosphor constituting the fluorescent member 41 can be extracted from the surface of the surface-side periodic structure layer 42 to the outside with high efficiency.
The aspect ratio, which is the ratio of the height h1 of the convex portion 43a to the period d1 in the surface-side periodic structure 43 of the surface-side periodic structure layer 42, is the surface-side period in the wavelength conversion member 20 of the fluorescent light source device shown in FIG. Similar to structure 43.

  The back-side periodic structure 45 formed on the surface of the back-side periodic structure layer 44 has a period d2 having a size within a range in which diffraction of fluorescence emitted from the phosphor constituting the fluorescent member 41 occurs. Is preferred. By satisfying such conditions, the fluorescence emitted from the phosphor constituting the fluorescent member 41 can be extracted from the surface of the surface-side periodic structure layer 42 to the outside with high efficiency.

As a material constituting the front-side periodic structure layer 42 and the back-side periodic structure layer 44 (hereinafter collectively referred to as “periodic structure layer”), the refractive index is the value of the refractive index of the fluorescent member 41. It is preferable to use the above. According to the structure of the periodic structure layer made of a material having a refractive index higher than the refractive index value of the fluorescent member 41, the fluorescence incident on the interface between the fluorescent member 41 and the periodic structure layer is transmitted through the interface. Causes refraction. For this reason, the fluorescence generated inside the wavelength conversion member 40 is changed not only on the back surface of the wavelength conversion member 40 but also on the interface between the fluorescent member 41 and the periodic structure layer, and its direction is the normal direction (surface Since it approaches (perpendicular to the surface of the side periodic structure layer 42), it is suppressed that the fluorescence is confined inside the wavelength conversion member 40.
Further, by using a material having a higher refractive index than that of the fluorescent member 41 as the material of the periodic structure layer, it is possible to form a periodic structure having a small period. Therefore, since the convex portion constituting the periodic structure can be designed with a small height even if the aspect ratio is large, the periodic structure can be easily formed. For example, when a nanoprint method is used, a mold (template) can be easily produced or imprinted. At this time, since the energy for exciting the phosphor in the wavelength conversion member 40 in which the periodic structure is formed has an excitation density of about 5 W / mm ² or more, the material constituting the periodic structure layer is an inorganic material. It is desirable.

As a material constituting the periodic structure layer, titania (refractive index 2.2), zirconia (refractive index 1.8), silicon nitride (refractive index 2.0), or the like can be used.
The thickness of the periodic structure layer is, for example, 0.1 to 1.0 μm.

  The periodic structure layer can be formed using a sol-gel method and a nanoimprint method. Specifically, a sol-like material containing an alkoxide such as titanium or zirconium is applied to the surface of the fluorescent member 41 by, for example, a spin coating method, and a heat treatment is performed while pressing a mold (template) mold, After releasing from the mold, heat treatment is performed. By this heat treatment, the reaction (hydrolysis and condensation polymerization) proceeds and a periodic structure layer made of an inorganic material is formed.

  In the fluorescent light source device described above, the excitation light that is the laser light in the blue region emitted from the laser diode is converted into parallel rays by the collimator lens. Thereafter, the excitation light passes through the dichroic mirror and is irradiated substantially perpendicularly to the excitation light receiving surface of the wavelength conversion member 40 in the fluorescent light emitting member, that is, the surface of the surface-side periodic structure layer 42, and the surface-side periodic structure. The light enters the fluorescent member 41 through the body layer 42. And in the fluorescent member 41, the fluorescent substance which comprises this fluorescent member 41 is excited. Thereby, fluorescence is emitted in the fluorescent member 41. The fluorescence is emitted from the fluorescence emission surface of the wavelength conversion member 40, that is, the surface of the surface-side periodic structure layer 42, reflected in the vertical direction by the dichroic mirror, and then emitted to the outside of the fluorescence light source device.

In this fluorescent light source device, the surface-side periodic structure layer 42 is provided on the surface of the fluorescent member 41 in the wavelength conversion member 40, and the surface of the surface-side periodic structure layer 42 forms an excitation light receiving surface. Yes. A surface-side periodic structure 43 is formed on the surface of the surface-side periodic structure layer 42. Therefore, when the wavelength conversion member 40 is irradiated with excitation light, backscattering of the excitation light is suppressed, and as a result, the excitation light can be taken into the wavelength conversion member 40 with high efficiency.
Further, on the back surface of the fluorescent member 41, a back surface side periodic structure layer 44 in which a back surface side periodic structure 45 is formed is provided, and the light reflection film 33 is provided on the back surface of the back surface side periodic structure body layer 44. ing. Therefore, the fluorescence emitted from the phosphor inside the wavelength conversion member 40 and incident on the back surface is reflected at a different angle on the back surface. Therefore, the directionality of the fluorescence that is repeatedly reflected in the wavelength conversion member 40 can be set to a direction perpendicular to the fluorescence emission surface of the wavelength conversion member 40. As a result, since the fluorescence is confined inside the wavelength conversion member 40, the fluorescence can be extracted from the surface of the wavelength conversion member 40 to the outside with high efficiency.
Further, since the period d1 of the front-side periodic structure 43 and the period d2 of the back-side periodic structure 45 are set to a size within a range where fluorescence diffraction occurring inside the wavelength conversion member 40 is generated, the efficiency is further increased. The fluorescence can be taken out from the surface of the wavelength conversion member 40.
Further, as the material constituting the periodic structure layer (the front-side periodic structure layer 42 and the back-side periodic structure layer 44), a material having a refractive index higher than the refractive index value of the fluorescent member 41 is used. Since the fluorescence incident on the interface between the fluorescent member 41 and the periodic structure layer is refracted, the direction of the fluorescence approaches the normal direction, so that the fluorescent material 41 is efficiently taken out from the surface of the surface-side periodic structure layer 42.
Therefore, according to the fluorescence light source device of FIG. 5, the excitation light can be sufficiently taken into the wavelength conversion member 40 and the fluorescence generated inside the wavelength conversion member 40 can be emitted to the outside with high efficiency. Therefore, high luminous efficiency can be obtained.

(Third embodiment)
In the fluorescent light source device according to the third embodiment, in the wavelength conversion member by the phosphor excited by the excitation light, the surface side periodic structure is formed on the surface that is the excitation light receiving surface, and the back surface is formed by the rough surface The light diffusing surface is provided, and a light reflecting film is provided outside the back surface.
Here, in this specification, the “rough surface” means rough surface treatment such as mechanical polishing (specifically, for example, blasting) and chemical polishing (specifically, for example, etching). It is the uneven surface formed by.

  As a specific example of the fluorescent light source device according to the third embodiment, for example, in the fluorescent light source device of FIG. 1 according to the first embodiment, the back surface of the fluorescent member constituting the wavelength conversion member is formed by a rough surface. Except for the light diffusing surface thus formed, one having the same configuration as that of the fluorescent light source device of FIG.

  In the fluorescent light source device described above, the excitation light, which is the laser light in the blue region emitted from the laser diode, is converted into parallel rays by the collimator lens. Thereafter, the excitation light passes through the dichroic mirror and is irradiated substantially perpendicularly to the excitation light receiving surface of the wavelength conversion member, that is, the surface of the fluorescent member. And in the wavelength conversion member, the fluorescent substance which comprises the fluorescent member in the said wavelength conversion member is excited, and fluorescence is emitted. The fluorescence is emitted from the fluorescence emission surface of the wavelength conversion member, that is, the surface of the fluorescence member, reflected in the vertical direction by the dichroic mirror, and then emitted to the outside of the fluorescence light source device.

In the fluorescent light source device according to the third embodiment, the surface-side periodic structure is formed on the surface of the fluorescent member that is the excitation light receiving surface of the wavelength conversion member. Therefore, when excitation light is irradiated to the fluorescent member, backscattering of the excitation light is suppressed, and as a result, the excitation light can be taken into the fluorescent member with high efficiency.
Further, the back surface of the fluorescent member provided with the light reflecting film is a light diffusion surface formed by a rough surface. Therefore, the fluorescence emitted from the phosphor in the fluorescent member and incident on the back surface of the fluorescent member is reflected at various angles. Therefore, the directionality of the fluorescence that is repeatedly reflected in the wavelength conversion member 20 can be set to a direction perpendicular to the surface of the fluorescence member that is the fluorescence emission surface of the wavelength conversion member. As a result, since the fluorescence is confined inside the fluorescent member, the fluorescent light can be taken out from the surface of the fluorescent member with high efficiency.
Therefore, according to the fluorescence light source device according to the third embodiment, the excitation light can be sufficiently taken into the wavelength conversion member, and the fluorescence generated inside the wavelength conversion member can be efficiently emitted to the outside. Since it can radiate | emit, high luminous efficiency is 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, in the fluorescent light source devices of the first embodiment and the second embodiment, the back surface-side periodic structure in the wavelength conversion member has a convex portion having a convex shape that decreases in diameter from the front surface toward the back surface. If it is, it will not be limited to what has a substantially cone-shaped convex part, You may have a convex part of another structure.
Specifically, the wavelength conversion member constituting the fluorescent light source device according to the first embodiment and the second embodiment has a hemispherical convex portion as shown in FIG. You may have.
Here, in the fluorescent light source device of FIG. 6, in the wavelength conversion member made of the fluorescent member 51 that constitutes the fluorescent light emitting member 20, the shape of the convex part (front side convex part) 52 a that constitutes the back side periodic structure 52 is hemispherical. Except for this, the configuration is the same as that of the fluorescent light source device of FIG.

  In the fluorescent light source device of FIG. 6, the period d <b> 2 of the back surface side periodic structure 52 is preferably in a range in which the diffraction of fluorescence emitted from the phosphor constituting the fluorescent member 51 occurs. By satisfying such conditions, the fluorescence emitted from the phosphor constituting the fluorescent member 51 can be extracted from the surface of the wavelength conversion member 50 to the outside with high efficiency.

Further, in the fluorescent light source device according to the first embodiment, the second embodiment, and the third embodiment, light transmittance is provided on the back surface where the back surface side periodic structure in the wavelength conversion member is formed. A member (hereinafter also referred to as a “stack member”) may be provided continuously, and the light reflection surface may be provided in a state of being separated from the back surface of the wavelength conversion member (see FIG. 7).
In this stacking member, a periodic structure that conforms to the periodic structure on the back surface side of the wavelength conversion member is formed on the surface located on the back surface side of the wavelength conversion member, and the wavelength is determined by the light-transmitting bonding member. It is joined to the conversion member 40. In addition, the stacking member has a refractive index different from that of the member on which the back-side periodic structure is formed so that refraction occurs on the back surface of the wavelength conversion member 40 (interface between the wavelength conversion member and the stacking member). It is said.
Specifically, in the fluorescent light source device of FIG. 7, the product made of the fluorescent member by the bonding member is provided on the back surface of the wavelength conversion member 40 having the fluorescent member 41, the front-side periodic structure layer 42, and the back-side periodic structure layer 44. A heavy member 47 is joined, and a stacked body of the wavelength conversion member 40 and the stacked member 47 is provided on a rectangular substrate 31. Further, a light reflecting film 33 made of, for example, silver is provided on each of the back surface (lower surface in FIG. 7) and the side surface of the joined body of the wavelength conversion member 40 and the stacking member 47. As described above, the light reflecting film 33 is formed on the back surface and the side surface of the joined body of the wavelength converting member 40 and the stacking member 47, so that the light reflecting surface is provided outside the back surface of the wavelength converting member 40. . Further, on the back surface of the substrate 31, for example, heat radiation fins (not shown) are arranged.
In this fluorescent light source device, the light reflecting film is not provided on the back surface of the back-side periodic structure layer 44 in the wavelength converting member 40, and the wavelength converting member 40 is provided with the light reflecting film 33 on the back surface and the side surface. Except for being provided on the rectangular substrate 31 with the stacking member 47 interposed, it has the same configuration as the fluorescent light source device of FIG. Moreover, the structure of the stacking member 47 made of a fluorescent member is the same as that of the fluorescent light source device of FIG. 1 except that the periodic structure is not formed on the back surface of the stacking member 47.

In the fluorescence light source device of FIG. 7, when the wavelength conversion member 40 is irradiated with excitation light, the excitation light is incident on the fluorescence member 41 of the wavelength conversion member 40 and is transmitted through the wavelength conversion member 40. Light is incident on the stacking member 47. Thereby, fluorescence (hereinafter also referred to as “first fluorescence”) is generated inside the wavelength conversion member 40, and fluorescence (hereinafter also referred to as “second fluorescence”) is also generated within the stacking member 47. Occurs.
Then, when the first fluorescence is incident on the interface between the back surface of the wavelength conversion member 40 and the stacking member 47, a part of the first fluorescence is reflected at a different angle on the interface, and the other part is reflected on the interface. By being transmitted, it is refracted and incident on the stacking member 47. Further, when the second fluorescence is incident on the interface between the back surface of the wavelength conversion member 40 and the stacking member 47, a part of the second fluorescence is reflected at a different angle at the interface, and the other part is reflected at the interface. By being transmitted, the light is refracted and incident on the wavelength conversion member 40.
As described above, the first fluorescence and the second fluorescence are generated at the interface between the stacking member 47 and the back-side periodic structure layer 44 and / or the fluorescent member 41 and the periodic structure layer (the front-side periodic structure layer 42 and The light enters the surface of the wavelength conversion member 40 through the interface with the back-side periodic structure layer 44). Therefore, the first fluorescent light and the second fluorescent light are changed in angle by passing through the interface in the wavelength conversion member 40, and thus are incident on the surface of the wavelength conversion member 40 at various angles. The trapping inside the conversion member 40 is suppressed.

In the fluorescent light source device according to the second embodiment, as shown in FIG. 5, the wavelength conversion member is limited to a configuration having a fluorescent member, a front-side periodic structure layer, and a back-side periodic structure layer. However, as long as it has at least one of the front-side periodic structure layer and the back-side periodic structure layer together with the fluorescent member, it may have other structures.
Specifically, the wavelength conversion member constituting the fluorescent light source device according to the second embodiment includes, for example, a fluorescent member and a surface-side periodic structure layer, and the surface of the surface-side periodic structure layer is excited light. The light receiving surface may have a configuration in which a back surface side periodic structure is formed on the back surface of the fluorescent member and a light reflecting film is provided. Further, it comprises a fluorescent member and a back-side periodic structure layer, a surface-side periodic structure is formed on the surface of the fluorescent member to serve as an excitation light receiving surface, and a light reflecting film is provided on the back surface of the back-side periodic structure layer. The thing of the structure provided may be sufficient.

In the fluorescent light source device according to the third embodiment, the wavelength conversion member is made of a fluorescent member, and the surface of the fluorescent member is an excitation light receiving surface and the back surface is a light diffusion surface formed by a rough surface. The structure is not limited to this, and the surface side periodic structure is formed on the surface that is the excitation light receiving surface, and the light diffusion surface formed by a rough surface on the back surface has other structures. May be.
Specifically, the wavelength conversion member constituting the fluorescent light source device according to the third embodiment includes, for example, a fluorescent member and a surface-side periodic structure layer, and the surface of the surface-side periodic structure layer is excited. The light receiving surface may be a light diffusing surface in which the back surface of the fluorescent member is a rough surface, and a light reflecting film may be provided. Also, a fluorescent member and a back surface side rough surface layer formed on the back surface of the fluorescent member, and the back surface of the back surface side rough surface layer is a light diffusion surface formed by a rough surface. There may be.

  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, experimental examples of the present invention will be described.

(Experimental example 1)
Based on the configuration shown in FIG. 5, a wavelength conversion member A having a surface-side periodic structure with the following specifications was produced.
[Substrate (31)]
Material: Aluminum substrate, Dimensions: 25 mm (length) x 25 mm (width) x 1 mm (thickness)
[Fluorescent member (41)]
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)
[Surface-side periodic structure layer (42)]
Material: silicon nitride (refractive index = 2.0), dimensions: 1.7 mm (length) x 3.0 mm (width) x 500 nm (thickness)
[Surface-side periodic structure (43)]
Convex part (43a) shape: conical, period (d1) = 268 nm, convex part (43a) height (h1) = 500 nm (ratio of convex part (43a) height (h1) to period (d1) (H1 / d1) = 2.0)
[Light Reflecting Film (33)]
Material: Silver, Thickness: 110nm

  Moreover, the wavelength conversion member B of the structure and specification similar to the wavelength conversion member A was produced except not having provided the surface side periodic structure body layer.

The excitation light receiving surface (surface of the periodic structure layer) of the wavelength conversion member A and the excitation light receiving surface (surface of the fluorescent member) of the wavelength conversion member B are each irradiated with excitation light having a peak wavelength of 445 nm. The light reflectance at the light receiving surface was measured.
As a result, in the wavelength conversion member A, the reflectance is 0.4%, whereas in the wavelength conversion member B, the reflectance is 15%, and in the wavelength conversion member A, the excitation light is behind. It was confirmed that scattering was sufficiently suppressed.

(Experimental example 2)
A wavelength conversion member C having the following specifications was produced according to the configuration shown in FIG.
[Substrate (31)]
Material: Aluminum substrate, Dimensions: 25 mm (length) x 25 mm (width) x 1 mm (thickness)
[Fluorescent member (21)]
Material: LuAG: Ce (refractive index = 1.85, excitation wavelength = 450 nm, fluorescence wavelength = 530 nm), dimensions: 1.7 mm (length) × 3.0 mm (width) × 130 μm (thickness)
Surface-side periodic structure (23): shape of convex part (23): conical, period (d1) = 292 nm, ratio of height (h1) of convex part (23) to period (d1) (h1 / d1) = 2.0
Back surface side periodic structure (25): shape of convex part (26): hemisphere with radius 0.015 mm, period (d2) = 0.03 mm, height of convex part (26) (h) = 0.01 nm
[Light Reflecting Film (33)]
Material: Silver, Thickness: 110nm

  Moreover, except not having provided the surface side periodic structure layer, while producing the wavelength conversion member D of the structure and specification similar to the wavelength conversion member C, and having not provided the back surface side periodic structure layer, A wavelength conversion member E having the same configuration and specifications as the wavelength conversion member C was produced.

Excitation light having a peak wavelength of 445 nm is irradiated to each of the wavelength conversion member C, the wavelength conversion member D, and the excitation light receiving surface (the surface of the fluorescent member) of the wavelength conversion member E, and the fluorescence emission surface (the surface of the fluorescent member) The light extraction efficiency and the light reflectance (back surface reflectance) on the back surface (back surface of the fluorescent member) were measured. The results are shown in FIG. In FIG. 8, the measurement value related to the wavelength conversion member C is shown by a triangular plot, the measurement value related to the wavelength conversion member D is shown by a rhombus plot, and the measurement value related to the wavelength conversion member E is shown by a square plot.
As a result, in the wavelength conversion member C, it was confirmed that the light extraction efficiency was sufficiently improved because the back surface side periodic structure was provided.
In this wavelength conversion member C, for example, the light extraction efficiency when the back surface reflectance is 98% is 84.7%, and the light extraction efficiency when the back surface reflectance is 98% is 67.5%. Compared to a certain wavelength conversion member E, the extraction efficiency is 1.25 times.

DESCRIPTION OF SYMBOLS 10 Laser diode 15 Collimator lens 16 Dichroic mirror 20 Fluorescent light emitting member 21 Fluorescent member 22 Surface side periodic structure 23 Convex part (surface side convex part)
24a Upper bottom part 25 Back surface side periodic structure 26 Convex part (back surface side convex part)
31 Substrate 33 Light Reflective Film 40 Wavelength Conversion Member 41 Fluorescent Member 42 Surface-side Periodic Structure Layer 43 Surface-side Periodic Structure 43a Convex Part (surface-side convex part)
44 Back side periodic structure layer 45 Back side periodic structure 45a Convex part (back side convex part)
47 Stacking Member 51 Fluorescent Member 52 Back Side Periodic Structure 52a Protrusion (Back Side Convex)
61 Fluorescent member 62 Substrate 63 Barium sulfate layer 64 Heat dissipation fin

Claims (7)

A fluorescent light source device comprising a wavelength conversion member made of a phosphor excited by excitation light,
The wavelength conversion member has a surface-side periodic structure formed on a surface that is an excitation light receiving surface, a back-side periodic structure is formed on the back surface, and a light reflecting surface is provided outside the back surface. A fluorescent light source device.   2. The fluorescent light source device according to claim 1, wherein the period of the surface-side periodic structure is a size within a range where diffraction of fluorescence emitted from the phosphor is generated.   3. The fluorescent light source device according to claim 1, wherein a period of the back-side periodic structure is a size in a range where diffraction of fluorescence emitted from the phosphor occurs.   The fluorescent light source device according to any one of claims 1 to 3, wherein the wavelength conversion member is entirely made of a fluorescent member containing a phosphor.   The wavelength conversion member is formed on a fluorescent member containing a phosphor, a surface-side periodic structure layer having a periodic structure on the surface, formed on the surface of the fluorescent member, and a back surface of the fluorescent member. The fluorescent light source device according to any one of claims 1 to 3, further comprising at least one periodic structure layer of the back-side periodic structure layer having a periodic structure on the back surface.   The fluorescent light source device according to claim 5, wherein a refractive index of the periodic structure layer formed on the fluorescent member is equal to or higher than a refractive index of the fluorescent member. A fluorescent light source device comprising a wavelength conversion member made of a phosphor excited by excitation light,
The wavelength conversion member has a surface-side periodic structure formed on the surface to be an excitation light receiving surface, a back surface is a light diffusion surface formed by a rough surface, and a light reflection surface is provided outside the back surface. A fluorescent light source device.

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