JP2015149217A - fluorescent light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescent light source device having high heat exhaust efficiency of a wavelength conversion member and accordingly, having high light emission efficiency.SOLUTION: A fluorescent light source device of this invention comprises: a heat radiation base; a plate-like wavelength conversion member made of a fluorescent material, which is arranged along the surface of the base; and an excitation light source which makes excitation light be incident on the wavelength conversion member. In the fluorescent light source device, the fluorescent material constituting the wavelength conversion member is made by containing light emitting substance in a base material made of ceramics, absorption coefficient of the excitation light of the wavelength conversion member is 1[mm] or less, the excitation light made incident on the wavelength conversion member is absorbed by the fluorescent material while advancing in the wavelength conversion member. It is preferable that in the fluorescent light source device of this invention, a light passage length until 90% of the excitation light is absorbed in a light passage where the excitation light made incident on the wavelength conversion member advances, is 7.7 mm or greater.

Description

  The present invention relates to a fluorescent light source device. More specifically, the present invention relates to a fluorescence light source device including a wavelength conversion member that emits fluorescence by irradiating excitation light from an excitation light source.

2. Description of the Related Art Conventionally, as a fluorescent light source device, a fluorescent light source device that includes a laser light source and a wavelength conversion member formed by a phosphor excited by laser light from the laser light source, and emits light of a desired color. It is known (for example, refer to Patent Document 1).
Specifically, Patent Document 1 discloses a projector apparatus shown in FIG. In this projector device, green region fluorescence comprising a laser light source 60 that emits laser light oscillating in the blue region as a green light source, a fluorescence wheel 64, and a wheel motor 69 for rotating the fluorescence wheel 64. A fluorescent light source device that emits light is used. The fluorescent wheel 64 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 60.
In FIG. 8, 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.
In such a fluorescent light source device, when the wavelength conversion member layer of the fluorescent wheel 64 is irradiated with laser light that oscillates in the blue region, green light is emitted.

Patent Document 2 proposes a fixed fluorescent light source device that does not have a rotation mechanism.
Specifically, as shown in FIG. 9, excitation is performed by laser light from a laser light source on an aluminum nitride substrate 72 placed on a heat dissipation plate 74 made of metal, on which a heat sink for heat dissipation 75 is formed. A wavelength conversion member 71 made of a phosphor (YAG sintered body) is made of barium sulfate and joined via a thermal expansion absorption layer 73 that relaxes the difference in thermal expansion coefficient between aluminum nitride and the phosphor. Discloses a fluorescent light source device fixed to a laser light source.

However, since a bright projector device requires a high-intensity light source that emits a large amount of light from a small area, it is necessary to increase the intensity [W / mm ² ] of the laser light incident on the phosphor serving as the light source. Usually, the absorption coefficient of the excitation light of the phosphor is about 10 [mm ⁻¹ ] or more, and the laser light is absorbed relatively locally in the vicinity of the incident surface of the phosphor. In the apparatus, there is a problem that it is difficult to efficiently exhaust the heat generated with the absorption of the laser light. If this heat exhaust efficiency is low, the phosphor itself cannot be suppressed from being heated, and as a result, the light emission efficiency is lowered due to temperature quenching of the phosphor itself.
In particular, a phosphor emitting fluorescence in the red region is a big problem because it has a large energy loss due to Stokes shift that occurs at the time of wavelength conversion and also has a large rate of decrease in luminous efficiency due to temperature quenching.

JP 2011-13316 A JP 2011-198560 A

  The present invention has been made based on the above circumstances, and an object of the present invention is to provide a fluorescent light source device in which the wavelength conversion member has high heat exhaust efficiency, and thus has high light emission efficiency.

The fluorescent light source device of the present invention includes a base for heat dissipation, a plate-like wavelength conversion member made of a phosphor arranged along the surface of the base, and an excitation light source that makes excitation light incident on the wavelength conversion member In the fluorescent light source device consisting of
The phosphor constituting the wavelength conversion member is a material in which a luminescent substance is contained in a base material made of ceramics, and the absorption coefficient of excitation light of the wavelength conversion member is 1 [mm ⁻¹ ] or less,
The excitation light incident on the wavelength conversion member is absorbed by the phosphor while traveling through the wavelength conversion member.

  In the fluorescent light source device of the present invention, it is preferable that an optical path length until 90% of the excitation light is absorbed is 7.7 mm or more in an optical path in which the excitation light incident on the wavelength conversion member travels. .

  In the fluorescent light source device of the present invention, it is preferable that the optical path of the excitation light in the wavelength conversion member has a plurality of reflection points reflected on a plurality of surfaces of the wavelength conversion member.

  In the fluorescence light source device of the present invention, it is preferable that the phosphor contained in the wavelength conversion member contains Pr or Sm.

  In the fluorescent light source device of the present invention, the excitation light source is a blue LD, an incident surface of excitation light is provided on a side peripheral surface of the wavelength conversion member, and the excitation light from the excitation light source passes through the collimator lens. It is preferably incident on the incident surface.

  In the fluorescent light source device of the present invention, the one having a low excitation light absorption coefficient is used as the wavelength conversion member, so that the absorption of the excitation light is gradually performed over a long optical path. That is, since the absorption of the excitation light is performed dispersively rather than locally, the heat generation location can also be dispersed throughout the wavelength conversion member. Accordingly, since a wide area of the wavelength conversion member can contribute to exhaust heat, the exhaust heat efficiency is high, and only a part of the phosphor constituting the wavelength conversion member is suppressed from being overheated and fluorescent. The occurrence of temperature quenching of the body is suppressed, and as a result, high luminous efficiency is obtained.

It is a top view which shows the outline of the structure in an example of the fluorescence light source device of the 1st Embodiment of this invention in the state which abbreviate | omitted the excitation light source. It is the XX sectional view taken on the line of FIG. It is a graph which shows the relationship between the absorption coefficient of the excitation light of a wavelength conversion member, and the optical path length until 90% of excitation light is absorbed. It is a top view which shows the outline of a structure in an example of the fluorescence light source device of the 2nd Embodiment of this invention. It is a top view which shows the outline of the structure in an example of the fluorescence light source device of the 3rd Embodiment of this invention in the state which abbreviate | omitted the base. It is a top view which shows the outline of a structure in an example of the fluorescence light source device of the 4th Embodiment of this invention. It is a right view of the fluorescence light source device of FIG. 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.

<First Embodiment>
FIG. 1 is a plan view showing an outline of the configuration of an example of the fluorescent light source device according to the first embodiment of the present invention in a state where an excitation light source is omitted, and FIG. 2 is a cross-sectional view taken along the line XX of FIG. It is.
As shown in FIG. 1, the fluorescent light source device includes a rectangular base 21 for heat dissipation, and, for example, a rectangular plate-shaped wavelength conversion member 20 made of a phosphor arranged along the surface of the base 21. An excitation light source (not shown) that causes the excitation light L1 to enter the wavelength conversion member 20 is provided.
In this fluorescent light source device, an inclined surface 20A is formed continuously on one surface of the surface (the upper surface in FIG. 2) and the side peripheral surface of the wavelength conversion member 20, and the inclined surface 20A is used as an incident surface for excitation light. Yes. The surface of the wavelength conversion member 20 is provided with a fluorescent reflector 24 having a rectangular opening 24H that reflects fluorescence toward the wavelength conversion member 20, and is exposed through the opening 24H on the surface of the wavelength conversion member 20. The area to function functions as a light exit surface.
A light reflector 25 that reflects fluorescence and excitation light toward the wavelength conversion member 20 is formed on the back surface (the lower surface in FIG. 2) of the wavelength conversion member 20. A light reflector that reflects fluorescence and excitation light toward the wavelength conversion member 20 may also be provided on the side peripheral surface of the wavelength conversion member 20.
Furthermore, for example, heat radiating fins (not shown) are arranged on the back surface of the base 21.

  The excitation light source only needs to be able to excite the phosphor in the wavelength conversion member 20, and examples of the excitation light source include blue LD (laser diode that emits light in the blue region) and blue LED (light in the blue region). For example, a light emitting diode).

  The material constituting the base 21 is CuW (Cu and W of Cu and W so that the heat from the back surface of the base 21 can be easily exhausted and the thermal stress on the wavelength conversion member 20 is small. A material that is excellent in thermal conductivity and has a small difference in thermal expansion coefficient from the wavelength conversion member 20 such as a pseudo alloy) or ALC (a composite material of Al and C) is used.

The phosphor constituting the wavelength conversion member 20 is obtained by adding an arbitrary amount of rare earth such as Ce, Pr, Sm as a luminescent substance to a ceramic sintered body such as YAG, LuAG, Y ₂ O ₃ .
In particular, Pr or Sm that emits fluorescence in the red region is preferably used as the light-emitting substance.

In the present invention, the absorption coefficient of the excitation light L1 of the wavelength conversion member 20 is 1 [mm ⁻¹ ] or less.
By making the absorption coefficient of the excitation light L1 of the wavelength conversion member 20 smaller, the excitation in the optical path along which the excitation light L1 incident on the wavelength conversion member 20 travels (hereinafter also referred to as “excitation light optical path”). The optical path length until 90% of the light L1 is absorbed (hereinafter also referred to as “90% absorption optical path length”) can be 7.7 mm or more.

The smaller the absorption coefficient of the excitation light L1 of the wavelength conversion member, the longer the 90% absorption optical path length.
The relationship between the absorption coefficient of the excitation light L1 of the wavelength conversion member and the 90% absorption optical path length is shown in the following Table 1 and the graph of FIG.

  The excitation light optical path in the wavelength conversion member 20 may have a plurality of reflection points that are reflected on a plurality of surfaces of the wavelength conversion member 20. By having such a configuration, a long excitation light optical path can be secured even in the small wavelength conversion member 20.

  The thickness of the wavelength conversion member 20 is, for example, 0.1 to 2.0 mm.

  Each of the fluorescent reflector 24 and the light reflector 25 may be a metal film or a dielectric multilayer film having a high reflectivity such as Ag formed on the surface of the wavelength conversion member 20, and the wavelength conversion member. What was formed as a member separate from 20 may be arranged.

  In this fluorescent light source device, from the viewpoint of suppressing the thermal resistance between the wavelength conversion member 20 and the base 21 low, the light reflector 25 and the base 21 are joined by solder, a heat conductive sheet, conductive grease, or the like. It is preferable to be bonded through the layer 28.

  Specifically, one example of the dimension example of the fluorescent light source device according to the first embodiment is 10 mm in the horizontal width (left-right direction in FIG. 1) and 8 mm in the vertical width (vertical direction in FIG. 1). The thickness is 0.8 mm, the horizontal width of the wavelength conversion member 20 (the horizontal direction in FIG. 1) is 6 mm, the vertical width (the vertical direction in FIG. 1) is 6 mm, and the horizontal width of the opening 24H (the horizontal direction in FIG. 1) is 3 mm. The vertical width (vertical direction in FIG. 1) is 2 mm, the angle of the inclined surface 20A that is the incident surface of the excitation light is 60 ° with respect to the surface of the wavelength conversion member 20, and from the surface of the base 21 to the surface of the wavelength conversion member 20 The total thickness is 1.2 mm.

  In the fluorescent light source device described above, the excitation light L1 emitted from the excitation light source is irradiated substantially perpendicularly to the inclined surface 20A that is the incident surface of the wavelength conversion member 20 on which the excitation light is incident. Then, the excitation light L1 incident on the wavelength conversion member 20 travels while being reflected by the front and back surfaces of the wavelength conversion member 20, and is gradually absorbed by the phosphor in the excitation light optical path. The fluorescence L2 is emitted by being excited. The fluorescence L2 is emitted from the opening 24H to the outside of the fluorescence light source device.

  In such a fluorescent light source device, the wavelength conversion member 20 having a low absorption coefficient of the excitation light L1 is used, so that the absorption of the excitation light L1 is gradually performed over a long excitation light optical path. That is, since the excitation light L1 is absorbed not locally but on the wavelength conversion member 20, the location where heat is generated can be dispersed throughout the wavelength conversion member 20. Therefore, since the wide area | region of the said wavelength conversion member 20 can be contributed to exhaust heat, it becomes a thing with high heat exhaust efficiency, and it is suppressed that only a part of fluorescent substance which comprises this wavelength conversion member 20 is overheated. Thus, the occurrence of temperature quenching of the phosphor is suppressed, and as a result, high luminous efficiency can be obtained.

<Second Embodiment>
The fluorescent light source device according to the second embodiment of the present invention has a pentagonal plate shape in which the wavelength conversion member has a substantially rectangular shape in plan view, and one corner of the wavelength conversion member is notched. . That is, as shown in FIG. 4, the wavelength conversion member 30 includes two long surfaces 30A and 30B that are parallel to each other extending in the longitudinal direction, and two short surfaces 30C and 30D that are perpendicular to these and parallel to each other. Of these surfaces, a plate-like one having a side peripheral surface composed of an inclined surface 30E continuous with a long surface 30A and a short surface 30C perpendicular to each other. The inclined surface 30E functions as an excitation light incident surface, and the short surface 30D not adjacent to the inclined surface 30E functions as a light emitting surface.
A fluorescent reflector 34 that reflects fluorescence toward the wavelength conversion member 30 is provided on the short surface 30 </ b> C and the inclined surface 30 </ b> E constituting the side peripheral surface of the wavelength conversion member 30.
A blue LD is used as the excitation light source 10, and between the excitation light source 10 and the wavelength conversion member 30, a collimating lens 15 that makes the excitation light L3 from the excitation light source 10 enter the inclined surface 30E as parallel light substantially perpendicularly. Is provided.
Except for the above configuration, the fluorescent light source device according to the first embodiment has the same configuration.

  Specifically, one example of the dimension example of the fluorescent light source device according to the second embodiment will be described. The length of the wavelength conversion member 30 in the longitudinal direction (the length in the left-right direction in FIG. 4) is 6 mm, The length (length in the vertical direction in FIG. 4) is 3 mm, the thickness is 2 mm, and the angle of the inclined surface 30E that is the incident surface of the excitation light is 45 ° with respect to the long surface 30A.

  In such a fluorescent light source device according to the second embodiment, substantially perpendicular to the inclined surface 30E that is the incident surface of the excitation light disposed on one end side in the longitudinal direction of the wavelength conversion member 30, and The excitation light L3 is irradiated so that the long surface 30B not adjacent to the inclined surface 30E is incident at an angle θ larger than the critical angle. Then, the excitation light L3 incident on the wavelength conversion member 30 travels through the wavelength conversion member 30 while being totally reflected by the long surfaces 30A and 30B on the side peripheral surface and, if necessary, the short surface 30D. The light is gradually absorbed by the phosphor in the optical path, and the phosphor L4 is emitted when the phosphor is excited. The fluorescence L4 is emitted to the outside of the fluorescence light source device from the short surface 30D disposed on the other end side in the longitudinal direction of the wavelength conversion member 30.

  According to such a fluorescent light source device according to the second embodiment, the same effect as that of the fluorescent light source device according to the first embodiment can be obtained.

<Third Embodiment>
The fluorescent light source device according to the third embodiment of the present invention is a plate-like one in which the shape of the wavelength conversion member is rectangular in plan view. That is, as shown in FIG. 5, the wavelength conversion member 40 is composed of two long surfaces 40A and 40B extending in the longitudinal direction and parallel to each other, and two short surfaces 40C and 40D perpendicular to these and parallel to each other. It is a plate-shaped thing which has a surrounding side surface.
In this fluorescent light source device, on the side peripheral surface of the wavelength conversion member 40, the entire surface excluding the specific region 40α constituting one end portion in the longitudinal direction of the long surface 40A that functions as the incident surface of the excitation light and the entire long surface 40B. A light reflector 45 that reflects fluorescence and excitation light toward the wavelength conversion member 40 is provided. In addition, a fluorescent reflector 44 that reflects fluorescence toward the wavelength conversion member 40 is provided on the entire short surface 40C adjacent to the specific region 40α that functions as the incident surface of the excitation light.
The specific area 40α of the long surface 40A functions as an excitation light incident surface, and the short surface 40D not adjacent to the specific region 40α functions as a light emission surface.
Except for the above configuration, the fluorescent light source device according to the second embodiment has the same configuration.

  Specifically, an example of a dimension example of the fluorescent light source device according to the third embodiment is described. The length of the wavelength conversion member 40 in the longitudinal direction (the length in the left-right direction in FIG. 5) is 9 mm, The length (vertical length in FIG. 5) is 3 mm, and the thickness is 2 mm.

  In such a fluorescent light source device according to the third embodiment, the wavelength conversion member 40 is arbitrarily set to be approximately perpendicular to the specific region 40α that is the incident surface of the excitation light disposed on one end side in the longitudinal direction. The excitation light L5 is irradiated at an angle. Then, the excitation light L5 incident on the wavelength conversion member 40 is directed toward the short surface 40D while being reflected by the light reflector 45 provided on the long surfaces 40A and 40B on the side peripheral surfaces in the wavelength conversion member 40. It proceeds and is gradually absorbed by the phosphor in the excitation light path, and the phosphor is excited to emit fluorescence L6. The fluorescence L6 is emitted to the outside of the fluorescence light source device from the short surface 40D disposed on the other end side in the longitudinal direction of the wavelength conversion member 40. The fluorescence emitted in the direction opposite to the short surface 40D, which is the light emitting surface, of the fluorescent light L6 is reflected by the fluorescent reflector 44 provided on the short surface 40C facing the short surface 40D, so that the short surface 40D is short. The light is emitted from the surface 40D.

According to the fluorescent light source device according to the third embodiment as described above, the same effects as those of the fluorescent light source device according to the first embodiment can be obtained.
Further, by adjusting the incident angle of the excitation light L5, the reflectance of the light reflector 45, the dimensions of the wavelength conversion member 40, etc., 90% absorption is achieved even when the absorption coefficient of the excitation light L5 of the wavelength conversion member 40 is extremely small. Since the optical path length can be reliably increased, a high degree of freedom in design can be obtained.

<Fourth embodiment>
In the fluorescent light source device according to the fourth embodiment of the present invention, the wavelength conversion member has a quadrangular frustum shape and a substantially plate shape. That is, as shown in FIGS. 6 and 7, the wavelength conversion member 50 includes a rectangular bottom surface 50D that functions as a light emitting surface, a rectangular top surface 50C that is opposed to the bottom surface 50C and that is smaller than the bottom surface 50D, and these It consists of four slopes 50A, 50B, 50E, 50F formed between the two. The four inclined surfaces 50A, 50B, 50E, and 50F are inclined so that at least one of them is separated from the normal line of the bottom surface 50D so as to be closer to the bottom surface 50D.
Of the four slopes 50A, 50B, 50E, and 50F, the areas of the two slopes 50E and 50F that face each other are larger than the two slopes 50A and 50B that face each other. The member 50 has a substantially plate shape with non-uniform thickness. Further, one of the two slopes 50E and 50F having a large area is the installation surface on the base 21.
In this fluorescent light source device, a fluorescent reflector 54 that reflects fluorescence toward the wavelength conversion member 50 is provided on the entire surface of the wavelength conversion member 50 except the bottom surface 50D that functions as a light emission surface. In addition, excitation light is applied to the entire surface of the slopes 50A and 50B, the top face 50C, and the bottom face 50D, which are side circumferential surfaces of the wavelength conversion member 50, except for the specific region 50α that constitutes one end adjacent to the top face 50C of the slope 50A. A light reflector 55 that reflects toward the wavelength conversion member 50 is provided.
The specific area 50α of the inclined surface 50A functions as an incident surface for excitation light, and the bottom surface 50D not adjacent to the specific area 50α functions as a light emission surface.
Except for the above configuration, the fluorescent light source device according to the third embodiment has the same configuration.

  Specifically, an example of dimensions of the fluorescent light source device according to the fourth embodiment is shown. The width of the base 21 (the horizontal direction in FIG. 6) is 12 mm, and the vertical width (the vertical direction in FIG. 6) is 7 mm. The thickness is 0.8 mm, the distance between the top surface 50C and the bottom surface 50D of the wavelength conversion member 50 (the length in the left-right direction in FIG. 6) is 8 mm, and the length in the width direction of the top surface 50C (the vertical direction in FIG. 6). The length in the width direction of the bottom surface 50D (length in the vertical direction in FIG. 6) is 3 mm, and the thickness in the direction perpendicular to the base 21 on the top surface 50C (the length perpendicular to the paper surface in FIG. 6). 1.5 mm, the thickness of the bottom surface 50D in the direction perpendicular to the base 21 (length perpendicular to the paper surface of FIG. 6) is 2 mm, and the width of the specific region 50α of the slope 50A (length in the left-right direction in FIG. 6) is 2 mm. It is.

  In such a fluorescent light source device according to the fourth embodiment, the excitation light L7 is irradiated at an arbitrary angle substantially perpendicular to the specific region 50α at one end of the wavelength conversion member 50. Then, the excitation light L7 incident on the wavelength conversion member 50 travels toward the bottom surface 50D while being reflected by the light reflector 55 provided on the inclined surfaces 50A and 50B facing each other in the wavelength conversion member 50, The light is gradually absorbed by the phosphor in the excitation light path, and the phosphor is excited to emit fluorescence. This fluorescence is emitted from the bottom surface 50D of the wavelength conversion member 50 to the outside of the fluorescence light source device. In addition, the fluorescence emitted in the direction different from the bottom surface 50D that is the light emitting surface of the fluorescence is emitted from the bottom surface 50D by being reflected by the fluorescent reflector 54 provided on the entire surface except the bottom surface 50D. The

According to such a fluorescent light source device according to the fourth embodiment, the same effects as those of the fluorescent light source device according to the third embodiment can be obtained.
Further, since the inclined surfaces 50A and 50B and / or the inclined surfaces 50E and 50F facing each other are not parallel to each other, it is possible to prevent the obtained fluorescence from being repeatedly reflected and confined in the wavelength conversion member 50. The extraction efficiency can be increased.

  The embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment. For example, a cylindrical lens is added after the collimating lens 15 and excitation light is applied to a thin phosphor. It is possible to make various changes such as providing the incident surface of the excitation light on the surface facing the light emitting surface.

<Example 1>
A fluorescent light source device having the shape shown in FIG. 1 was produced. This fluorescent light source device is referred to as device [1]. Specifically, it is as follows.
Excitation light source: Blue LD (peak wavelength 450 nm)
・ Base: Width: 10mm, Length: 8mm, Thickness: 0.8mm
-Phosphor: YAG (Ce: 0.005 mol%)
・ Wavelength conversion member: Width: 6 mm, Length: 6 mm, Width of opening: 3 mm, Length: 2 mm, Angle of slope of excitation light incident surface to wavelength conversion member surface: 60 °, surface of base Total thickness from the surface of the wavelength conversion member to 1.2 mm:
-Absorption coefficient of excitation light of wavelength conversion member; 0.3 mm [mm ^-1 ]
・ 90% absorption optical path length: 7.7mm

<Example 2>
A fluorescent light source device having the shape shown in FIG. 4 was produced. This fluorescent light source device is referred to as device [2]. Specifically, it is as follows.
Excitation light source: Blue LD (peak wavelength 450 nm)
・ Base: Width: 8mm, Length: 7mm, Thickness: 0.8mm
-Phosphor: YAG (Ce: 0.005 mol%)
Wavelength conversion member: length in the longitudinal direction: 6 mm, length in the width direction: 3 mm, thickness: 2 mm, angle with respect to the long surface of the inclined surface that is the incident surface of the excitation light: 45 °
-Absorption coefficient of excitation light of wavelength conversion member; 0.3 mm [mm ^-1 ]
・ 90% absorption optical path length: 7.7mm

<Example 3>
A fluorescent light source device having the shape shown in FIG. 5 was produced. This fluorescent light source device is referred to as device [3]. Specifically, it is as follows.
Excitation light source: Blue LD (peak wavelength: 440 nm)
・ Base: Width: 12mm, Length: 7mm, Thickness: 0.8mm
-Phosphor: YAG (Pr: 0.6 mol%)
-Wavelength conversion member: length in the longitudinal direction: 9 mm, length in the width direction: 3 mm, thickness: 2 mm
-Absorption coefficient of excitation light of wavelength conversion member; 0.1 mm [mm ^-1 ]
・ 90% absorption optical path length: 23mm

<Example 4>
A fluorescent light source device having the shape shown in FIG. 6 was produced. This fluorescent light source device is referred to as device [4]. Specifically, it is as follows.
Excitation light source: Blue LD (peak wavelength: 440 nm)
・ Base: Width: 12mm, Length: 6mm, Thickness: 0.8mm
-Phosphor: YAG (Pr: 0.6 mol%)
Wavelength conversion member: distance between top surface and bottom surface: 9 mm, length in the width direction of the top surface: 2 mm, length in the width direction of the bottom surface: 3 mm, thickness in the direction perpendicular to the base on the top surface: 1.5 mm , Thickness in the direction perpendicular to the base at the bottom: 2 mm, width of the specific area: 2 mm
-Absorption coefficient of excitation light of wavelength conversion member; 0.1 mm [mm ^-1 ]
・ 90% absorption optical path length: 23mm

  The relative fluorescence intensity of the fluorescent light source devices [1] to [4] was measured. The results are shown in Table 2. The calculation was performed using the fluorescence intensity of the fluorescent light source device [2] according to Example 2 as the reference (1.0).

DESCRIPTION OF SYMBOLS 10 Excitation light source 15 Collimating lens 20 Wavelength conversion member 20A Slope 21 Base 24 Fluorescence reflector 24H Opening part 25 Light reflector 28 Bonding layer 30 Wavelength conversion members 30A, 30B Long surface 30C, 30D Short surface 30E Slope 34 Fluorescent reflector 40 Wavelength conversion member 40A, 40B Long surface 40C, 40D Short surface 40α Specific region 44 Fluorescent reflector 45 Light reflector 50 Wavelength conversion member 50A, 50B, 50E, 50F Slope 50C Top surface 50D Bottom surface 50α Specific region 54 Fluorescent reflector 55 Light Reflector 60 Laser light source 61 Collimate lens 62 Red light source 63A, 63B, 63C, 64A, 64B, 64C Condensing lens 64 Fluorescent wheel 65 Dichroic mirror 66 Light guide device incident lens 67 Reflective mirror 68 Light guide device 69 Wheel motor 71 Wavelength conversion Member 72 Aluminum nitride substrate 73 Expansion absorbing layer 74 heat dissipation plate 75 heat sink for radiating heat

Claims (5)

In a fluorescent light source device comprising a base for heat dissipation, a plate-like wavelength conversion member made of a phosphor, arranged along the surface of the base, and an excitation light source that makes excitation light incident on the wavelength conversion member,
The phosphor constituting the wavelength conversion member is a material in which a luminescent substance is contained in a base material made of ceramics, and the absorption coefficient of excitation light of the wavelength conversion member is 1 [mm ⁻¹ ] or less,
Excitation light incident on the wavelength conversion member is absorbed by the phosphor while traveling through the wavelength conversion member.   2. The fluorescence according to claim 1, wherein an optical path length until 90% of the excitation light is absorbed is 7.7 mm or more in an optical path in which the excitation light incident on the wavelength conversion member travels. Light source device.   The fluorescent light source device according to claim 2, wherein the optical path of the excitation light in the wavelength conversion member has a plurality of reflection points reflected on a plurality of surfaces of the wavelength conversion member.   The fluorescent light source device according to claim 2, wherein the phosphor contained in the wavelength conversion member contains Pr or Sm. The excitation light source is a blue LD, an excitation light incident surface is provided on a side peripheral surface of the wavelength conversion member, and excitation light from the excitation light source is incident on the incident surface via a collimator lens. The fluorescent light source device according to claim 2.

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