JP2015122447A - Light-emitting device and illumination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an effect of suppressing degradation of a wavelength conversion member when an emission end part of a light guide part is made close to the wavelength conversion member.SOLUTION: The light-emitting device includes: a light guide part (5) emitting light propagating through a light propagation part formed of a material whose base material is a material having transparency; and a wavelength conversion member (6). A tip part (5a), which is an end part of the light-emission side of the light propagation part has a configuration in which a diameter of a cross section perpendicular to a direction of light propagation is monotonously increasing when approaching to the wavelength conversion member (6) side.

Description

  The present invention relates to a light-emitting device that uses wavelength-converted light generated by irradiating a wavelength conversion member as illumination light, and an illumination device including the light-emitting device.

  In recent years, a semiconductor light emitting device such as a semiconductor laser (LD) is used as an excitation light source, and wavelength conversion light generated by irradiating the wavelength conversion member with excitation light generated from these excitation light sources is used as illumination light. Research on light-emitting devices has become active.

  As an example of such a light emitting device, there is a light source device disclosed in Patent Document 1. As shown in FIG. 7 (a), this apparatus includes: a light guide emitting end portion that is a portion that emits excitation light guided by a light guide; and a pumping light diffusing means such as a concave lens; and a wavelength conversion member. Optimizing the distance, the effective area of the excitation light diffusing means, the range of the wavelength conversion area of the wavelength conversion member, and the like increase the use efficiency of the excitation light.

  Another example is a semiconductor light emitting device disclosed in Patent Document 2. In this apparatus, as shown in FIG. 7 (b), an opening is formed substantially at the center of the upper surface of the cap body and penetrates the inside and outside of the cap body, and the wall surface of the opening forms an inclined portion. The opening width of the opening has a tapered shape that increases from the light incident portion in accordance with the traveling direction of the light, so that the light emitted from the LD element is efficiently emitted out of the semiconductor light emitting device.

  Another example is a light emitting device disclosed in Patent Document 3. In this apparatus, as shown in FIG. 7C, the light guide and at least a part of the light guide tip member are covered with the wavelength conversion member.

JP 2010-81957 A (released on April 15, 2010) JP 2008-153617 A (released July 3, 2008) JP 2006-253099 A (published September 21, 2006)

  However, the conventional techniques as described above have the following problems. For example, in the apparatus described in Patent Document 1, an optical medium different from the light guide, such as air or a concave lens, surrounded by a tapered holding member is provided between the light guide emission end portion and the wavelength conversion member. It is an existing space. Therefore, the irradiation efficiency of the excitation light to the wavelength conversion member is reduced due to the presence of another optical medium such as a concave lens or air between the wavelength conversion member and the light guide exit end. There is a problem. Further, in the apparatus described in Patent Document 2, since the distance between the LD element that emits the excitation light and the wavelength conversion member is large and there is a region where air exists, the wavelength conversion member for the excitation light is not affected. There is a problem that the incidence efficiency (or irradiation efficiency) is lowered. In order to solve the above-described problems, it is preferable that the light guide emission end and the LD element be as close as possible to the wavelength conversion member. However, in the techniques of these documents, the diameter of the cross section of the light emitting point of the light guide or LD element is considerably smaller than the size of the wavelength conversion member, so the light guide emission end or LD element is used as the wavelength conversion member. If approached as it is, the excitation light is concentrated on a part of the wavelength conversion member, which may cause deterioration of the wavelength conversion member.

  Next, Patent Document 3 describes that the area of the end surface of the light guide tip member is increased in order to increase the contact area between the light guide tip member and the wavelength conversion member. However, in the apparatus described in this document, the diameter of the cross section of the light guide that is perpendicular to the light traveling direction remains considerably smaller than the size of the wavelength conversion member. Since it is connected to the wavelength conversion member, the excitation light is concentrated on a part of the wavelength conversion member, which may cause deterioration of the wavelength conversion member.

  The present invention has been made in view of the above-described problems, and its purpose is to improve the effect of suppressing deterioration of the wavelength conversion member when the exit end of the light guide unit is brought close to the wavelength conversion member. An object of the present invention is to provide a light-emitting device that can be used.

  In order to solve the above problems, a light-emitting device according to one embodiment of the present invention includes a light propagation portion formed using a material using a light-transmitting material as a base material, and propagates through the light propagation portion. A light guide part that emits light, and a wavelength conversion member that converts a wavelength of light emitted from the light guide part, and an emission end part that is an end part on the light emission side of the light propagation part is light The diameter of the cross section perpendicular to the traveling direction is monotonously increased as it approaches the wavelength conversion member side.

  According to one aspect of the present invention, there is an effect of improving the effect of suppressing deterioration of the wavelength conversion member when the exit end portion of the light guide portion is brought close to the wavelength conversion member.

It is sectional drawing which shows the structure of the light-emitting device which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the light-emitting device which concerns on a comparative example, (a) is sectional drawing which shows the structure of the light-emitting device which concerns on the comparative example 1, (b) is the structure of the light-emitting device which concerns on the comparative example 2. It is sectional drawing shown. It is sectional drawing which shows the structure of the light-emitting device which concerns on Embodiment 2 of this invention. It is a figure which shows the structure of the light-emitting device which concerns on Embodiment 3 of this invention, and the optical characteristic of the said light-emitting device, (a) is sectional drawing which shows the structure of the said light-emitting device, (b) is the said It is a graph which shows the relationship between the light output of an excitation light source, and the total luminous flux of the light output from the said light-emitting device regarding a light-emitting device. It is a figure which shows the structure of the light-emitting device which concerns on Embodiment 4 of this invention, and the optical characteristic of the light-emitting device which concerns on Embodiment 1, 3, and 4 of this invention, (a) is light emission which concerns on the said Embodiment 4. It is sectional drawing which shows the structure of an apparatus, (b) is related with the light-emitting device which concerns on the said Embodiment 1, 3, and 4, and shows the relationship between the light output of an excitation light source, and the total light beam output from these light-emitting devices. It is a graph to show. It is a figure which shows the structure of the illuminating device which concerns on Embodiment 5 and its modification of this invention, (a) is sectional drawing which shows the structure of the illuminating device which concerns on the said Embodiment 5, (b) is the said It is sectional drawing which shows the structure of the illuminating device which concerns on a modification. It is a figure which shows the structure of the conventional light-emitting device, (a) is sectional drawing which shows the structure of an example of the conventional light-emitting device, (b) is sectional drawing which shows the structure of another example, (c) And (d) is sectional drawing which shows the structure of another example.

  An embodiment embodying the present invention will be described below with reference to FIGS. Hereinafter, descriptions of configurations other than those described in the specific embodiment may be omitted as necessary, but when described in other embodiments, the configurations are the same. For convenience of explanation, members having the same functions as those shown in each embodiment are given the same reference numerals, and the explanation thereof is omitted as appropriate.

[Embodiment 1: Light-emitting device 10]
First, based on FIG. 1, the structure of the light-emitting device (illuminating device) 10 which concerns on Embodiment 1 of this invention is demonstrated. FIG. 1 is a cross-sectional view showing the structure of the light emitting device 10. The light emitting device 10 of this embodiment uses a semiconductor laser (LD) as an excitation light source, and wavelength converted light (fluorescence) generated by irradiating the wavelength conversion member with excitation light (laser light) generated from the excitation light source. It is a light-emitting device which uses as an illumination light. As shown in FIG. 1, the light emitting device 10 includes an excitation light source 1, an optical fiber 2, a covering portion 4, a light guide portion 5, a wavelength conversion member 6, and a reflector (reflecting mirror) 7.

(Excitation light source 1)
The excitation light source 1 is a device that generates excitation light, and includes at least one LD. Although only one LD may be used, it is easier to use a plurality of LDs in order to obtain a high-power laser beam. The oscillation wavelength of the LD of the present embodiment is a wavelength in the wavelength range of 440 nm to 460 nm (blue region), but is not limited thereto. For example, the oscillation wavelength of the LD may be a wavelength in the wavelength range of 370 nm to 420 nm (near ultraviolet region to blue-violet region), and has an emission peak wavelength in the wavelength range from the near ultraviolet region to blue region (350 nm to 460 nm or less). Anything is fine. Further, the optical output of the LD of the present embodiment is 1.2 W, the operating voltage is 4.7 V, and the operating current is 0.8 A.

  In addition, although the excitation light source 1 of this embodiment is comprised from LD, the excitation light source 1 may be comprised from light sources other than LD. A high output LED (Light Emitting Diode) chip may be used instead of the LD.

(Optical fiber 2)
The optical fiber 2 is a light guide member that guides the excitation light output from the excitation light source 1 to the light guide unit 5. The excitation light source 1 is optically connected to the light guide unit 5 through the optical fiber 2. The base material of the optical fiber 2 is quartz glass (silicon oxide acid; refractive index 1.45 to 1.48), and a dopant is added as necessary. The optical fiber 2 has a two-layer structure in which an inner core is covered with a clad having a refractive index lower than that of the core. The refractive index of the core is 1.463 to 1.467, and the refractive index of the cladding is 1.45 to 1.46. The optical fiber 2 of the present embodiment has a structure in which the core diameter is 114 μm, the cladding diameter is 125 μm, and the numerical aperture NA (Numerical Aperture) is 0.20. It is not limited to those.

  Moreover, although the shape of the cross section perpendicular | vertical with respect to the advancing direction of the optical fiber 2 of this embodiment is circular, the shape of a cross section is not limited to this. For example, the cross-sectional shape may be a rectangle or the like. In the light emitting device 10 of the present embodiment, the distance between the wavelength conversion member 6 and the excitation light source 1 (semiconductor laser) is separated by the optical fiber 2. As a result, since the heat generation in the wavelength conversion member 6 and the excitation light source 1 can be separated, the wavelength conversion member 6 is not affected by the heat generation of the excitation light source 1. Thereby, the magnitude | size of the light-emitting device 10 whole except the excitation light source 1 can be made small.

(Coating part 4, light guide part 5)
The light guide part 5 has a core (light propagation part) 5b in the center, and guides the excitation light received from the optical fiber 2 to the tip part (emission end part, light propagation part) 5a of the light guide part 5. It is a light guide member. The tip 5a is optically connected to the core 5b. The light guide 5 is made of a material having a light-transmitting material as a base material (for example, quartz glass), and a dopant is added to the base material as necessary. The base material of the light guide 5 may be a resin material other than inorganic glass such as quartz, but it is preferable to make the difference in refractive index between the resin material and the wavelength conversion member 6 as small as possible. The light guide 5 has a two-layer structure in which the core 5b is covered with a clad 5c having a refractive index lower than that of the core 5b. Similar to the optical fiber 2 described above, the core 5b has a refractive index of 1.463 to 1.467, and the cladding 5c has a refractive index of 1.45 to 1.46. The front end portion 5a is a portion from which excitation light guided by the core 5b of the light guide portion 5 is emitted, and the refractive index thereof is 1.463 to 1.467.

  As shown in FIG. 1, the tip 5a has a structure (reflector structure) that monotonously increases as the diameter of the cross section perpendicular to the light traveling direction approaches the wavelength conversion member 6 side. For this reason, the spot diameter of the light guided to the front-end | tip part 5a can be expanded. Thereby, even if the front end 5a is brought close to the wavelength conversion member 6, it is possible to suppress the concentration of the excitation light partially in a narrow range of a part of the wavelength conversion member 6. Can be suppressed. As described above, it is possible to improve the effect of suppressing deterioration of the wavelength conversion member 6 when the distal end portion 5a is brought close to the wavelength conversion member 6.

  Next, for example, in the light emitting device having the structure as in Comparative Example 1 shown in FIG. 2A, even when the wavelength conversion member is irradiated with the excitation light, a part of the excitation light is reflected by the wavelength conversion member. There is a problem in that it returns to the rear in the traveling direction of the illumination light, and the luminous efficiency of the light emitting device is lowered. Further, in the light emitting device of Comparative Example 1, the fluorescence from the phosphor in the wavelength conversion member also travels not only forward but also backward in the traveling direction of the illumination light, so that the light extraction efficiency as the light emitting device is reduced. There is also a problem that it ends up.

  On the other hand, in the light emitting device 10 of the present embodiment, the light guide unit 5 side is obtained by combining the reflector structure of the tip portion 5a described above and the interface between the covering unit 4 and the light guide unit 5 being a mirror surface. The wavelength-converted light (fluorescence) and the excitation light that have returned to the above are reflected so that the illumination light of the light emitting device 10 can be easily emitted forward in the traveling direction. For this reason, the light emission efficiency as a light-emitting device and the light extraction efficiency can be improved.

  Next, as shown in FIG. 1, the end surface (light guide unit end surface SUF3) on the front end portion 5a side of the present embodiment is a light irradiation side surface (light emitting unit surface SUF2) to which the excitation light of the wavelength conversion member 6 is irradiated. ). For this reason, the irradiation of excitation light caused by the distance between the wavelength conversion member 6 and the tip 5a being separated, or the presence of another optical system or the like between the wavelength conversion member and the emission end. A decrease in efficiency (or incident efficiency) can be suppressed. More specifically, the light guide part end surface SUF3 of the tip part 5a of the present embodiment is in contact with the light emitting part surface SUF2 of the wavelength conversion member 6. Or the front-end | tip part 5a is inserted toward the inside of the wavelength conversion member 6 from the light emission part surface SUF2 side of the wavelength conversion member 6. FIG. Thereby, the loss of light at the interface between the wavelength conversion member 6 (light emitting part surface SUF2) and the tip part 5a (light guide part end surface SUF3) is reduced.

  Next, the covering portion 4 covers the periphery of the side surface along the optical axis direction of the light guide portion 5. The material of the covering portion 4 is preferably a material having high thermal conductivity and good light reflectivity. For example, a metal material such as Al can be exemplified. Thereby, the periphery of the side surface along the optical axis direction of the light guide portion 5 can be thermally connected to a heat sink 9 described later to enhance heat dissipation. Further, by covering the light guide part 6 with the cover part 4, the interface (cover part surface SUF1) between the cover part 4 and the light guide part 5 serves as a mirror, and the return light (excitation) from the wavelength conversion member 6 Light or wavelength-converted light) is easily incident on the wavelength conversion member 6 again.

(Wavelength conversion member 6)
The wavelength conversion member 6 is a member that converts the wavelength of incident light (excitation light) and emits light having a wavelength different from that of the incident light. The wavelength conversion member 6 of the present embodiment is obtained by sealing a phosphor with a sealing agent (or holding member). In the present embodiment, a Ca-α-SiAlON: Eu phosphor (sialon phosphor) that emits yellow to orange light is used.

α-Sialon is a material that has been studied as a high-temperature structural material because it has high hardness, high strength, and excellent heat resistance. The crystals are solid solution having the same crystal structure as silicon α- nitride, the general formula _{Si 12- (m + n) Al} (m + n) O n N 16-n (m + n <12,0 <m, n <11; m, There are two voids in the unit structure consisting of 28 atoms represented by (n is an integer), and various metals can enter and dissolve therein. A phosphor is obtained by dissolving a rare earth element. When calcium (Ca) and europium (Eu) are dissolved, a longer wavelength than the YAG: Ce phosphor, which is the most commonly used yellow-emitting phosphor (hereinafter simply referred to as “yellow phosphor”). Ca-α-SiAlON: Eu phosphor having good characteristics of emitting light in the yellow to orange range. White light (pseudo white) is output as a mixture of the orange light emission and the blue color of the laser light emitted from the excitation light source 1, and light emission of a good bulb color can be obtained.

  Although the shape of the wavelength conversion member 6 is not specifically limited, For example, a disk-shaped thing can be used. In this example, a disk-shaped one having a thickness of 0.5 to 3 mm was used. The mixing amount of the phosphor with respect to the sealing agent (the base material of the wavelength conversion member 6) was adjusted so that the color temperature as the light emitting device was about 3000K.

  The sealant (the base material of the wavelength conversion member 6) is preferably an inorganic glass such as quartz glass (silicon oxide; refractive index: 1.45 to 1.48) that does not contain an organic component, but has an extremely high output. As long as excitation light at high light density is not used, a resin such as silicone resin or organic hybrid glass may be used.

  The deterioration of the wavelength conversion member 6 is considered to be mainly caused by the deterioration of the phosphor sealing agent (for example, silicone resin) contained in the wavelength conversion member 6. That is, the sialon phosphor generates fluorescence with an efficiency of 60 to 80% when irradiated with laser light, but the rest is released as heat. It is considered that the sealant deteriorates due to this heat. Therefore, as the sealant, a sealant with high heat resistance is preferable. In order to reduce the difference in refractive index between the light guide 5 and the wavelength conversion member 6, it is preferable that the base material of the light guide 5 and the sealant are made of the same material. Therefore, in the wavelength conversion member 6 of the present embodiment, quartz glass that has high heat resistance and is the same material as the base material of the light guide unit 5 is used as a sealant. Thereby, while improving the heat resistance of the wavelength conversion member 6, the refractive index difference of the light guide part 5 and the wavelength conversion member 6 can be made small, and the loss of the light in the interface of the wavelength conversion member 6 and the light guide part 5 is lost. Can be reduced. As described above, it is possible to suppress the deterioration of the wavelength conversion member 6 and the decrease in the irradiation efficiency of the excitation light with respect to the wavelength conversion member 6.

  Next, in general, white (or pseudo-white) light used as illumination light is a mixture of three colors of R (red), G (green), and B (blue), or two types satisfying a complementary color relationship. This can be achieved by mixing colors. For example, white (or pseudo-white) light can be realized by mixing the color of the fluorescence emitted from the phosphor included in the wavelength conversion member 6 and the color of the laser light emitted from the excitation light source 1. More specifically, the light emitting device 10 of this embodiment is a color mixture of the yellow fluorescent light emitted from the yellow phosphor included in the wavelength conversion member 6 and the blue color of the laser light emitted from the excitation light source 1. Thus, white light (pseudo white) is output. As described above, in this embodiment, the α-SiAlON: Eu phosphor is used as the yellow phosphor, but the type of the phosphor is not limited to this.

  For example, the wavelength conversion member 6 includes a blue light emitting phosphor (hereinafter simply referred to as “blue phosphor”), a green light emitting phosphor (hereinafter simply referred to as “green phosphor”), and a red light emitting phosphor (hereinafter simply referred to as “ Red phosphor ”) may be dispersed in a sealant. When a green phosphor and a red phosphor are used as the phosphor included in the wavelength conversion member 6, white light is output in a mixed color with the blue of the laser light emitted from the excitation light source 1. In this case, white light with higher color rendering can be obtained.

  Moreover, you may use the laser beam of a near ultraviolet region to a blue-violet region (370 nm or more and 420 nm or less) for the excitation light source 1, As a fluorescent substance contained in the wavelength conversion member 6 in this case, a blue fluorescent substance, a green fluorescent substance, By using the red phosphor, white light is output in a color mixture with the blue-violet laser light emitted from the excitation light source 1. In this case, good white light with higher color rendering can be obtained.

  In addition, the light irradiation side surface (light emitting unit surface SUF2) on which the light of the wavelength conversion member 6 of the present embodiment is irradiated is joined to the bottom portion near the focal point of the light reflecting concave surface of the reflector 7 described later. For this reason, the wavelength conversion member 6 has a disk-like shape (or a shape for sealing the bottom) along the shape of the light reflecting concave surface in the vicinity of the bottom of the light reflecting concave surface of the reflector 7. Since the wavelength conversion member 6 and the reflector 7 are integrated by the above, the extraction efficiency of the light from the wavelength conversion member 6 can be improved.

(Reflector 7)
The reflector 7 forms a light bundle that travels within a predetermined solid angle by reflecting a part of the wavelength-converted light (fluorescence) emitted from the wavelength conversion member 6. That is, the reflector 7 reflects the fluorescence from the wavelength conversion member 6 to form a light beam that travels forward (in the optical axis direction) of the light emitting device 10. The reflector 7 is, for example, a curved surface (cup-shaped curved surface) member having a metal thin film formed on the surface thereof, has a light reflecting concave surface that reflects light, and travels in the traveling direction of reflected fluorescence (illumination light). It is open.

<Effect of the light emitting device 10>
Here, in order to verify the effect of the light emitting device 10 of the present embodiment, the light emitting device of the comparative example was prototyped, and the effect of the light emitting device 10 and the effect of the light emitting device of the comparative example were compared. The comparison result will be described.

  The light emitting device of Comparative Example 1 shown in FIG. 2A differs from the light emitting device 10 in that no light guide member exists between the LD element and the wavelength conversion member. For this reason, in the light-emitting device of Comparative Example 1, in the light-emitting device 10, the tip 5a has a reflector structure, the difference in refractive index between the light guide 5 and the wavelength conversion member 6, and the tip 5a. However, the merit obtained from the point which is contacting the wavelength conversion member 6 or inserted in the wavelength conversion member 6 cannot be enjoyed.

  On the other hand, the light emitting device of Comparative Example 2 shown in FIG. 2B is different from the light emitting device 10 in that the tip portion 5a does not have a reflector structure. That is, in the light emitting device of Comparative Example 2, the advantage obtained from the point that the tip portion 5a of the light emitting device 10 has a reflector structure cannot be enjoyed.

  Table 1 below shows the result of comparing the total luminous flux of the illumination light emitted from the light-emitting device 10 of Embodiment 1 with reference to the total luminous flux of the illumination light emitted from the light-emitting device of Comparative Example 1, and Comparative Example 2 The result of having compared the total luminous flux of the illumination light emitted from the light emitting device 10 of Embodiment 1 on the basis of the total luminous flux of the illumination light emitted from the light emitting device is shown. The light output of the LD, which is an excitation light source, was the same output. In Embodiment 1, the total luminous flux was improved by 1.5 times compared to Comparative Example 1. Further, in Embodiment 1, the total luminous flux was improved 1.3 times compared to Comparative Example 2. From this comparison result, it is understood that the total luminous flux of the illumination light can be remarkably improved by making the tip portion 5a a reflector structure.

<Relationship between problems of conventional technology and effects of light emitting device 10>
In the light source device described in Patent Document 1 described above (see FIG. 7A), the sealant that seals the phosphor of the wavelength conversion member is a silicone resin (refractive index is 1.4). For this reason, even if a concave lens as excitation light diffusing means is provided between the light guide exit end and the wavelength conversion member, the sealant deteriorates quickly if the light output (power) of the excitation light is increased. There is a problem that. However, in the light emitting device 10 of this embodiment, as described above, the phosphor sealing agent in the wavelength conversion member 6 is quartz glass. The phosphor is an oxynitride phosphor. For this reason, even if the optical output of the laser beam is increased, it is difficult to deteriorate.

  Next, in the light source device described in Patent Document 1, a space surrounded by a tapered holding member is provided between the light guide emitting end and the wavelength conversion member. Therefore, the presence of a concave lens or air between the wavelength conversion member and the light guide exit end, the light guide exit end, air, and the refractive index of each of the wavelength conversion member (silicone resin; refractive index 1.4) The problem is that the irradiation efficiency of the excitation light to the wavelength conversion member decreases due to the difference being significant, the distance between the light guide exit end and the wavelength conversion member being separated, etc. There is a point. Further, in the semiconductor light source device described in Patent Document 2 described above (see FIG. 7B), the distance between the LD element that emits the excitation light and the wavelength conversion member is separated, and air or wavelength conversion is performed. Since there is a region (≧ 1.4) having a significantly different refractive index, such as a region where the member is present, there is a problem that the incident efficiency of the excitation light to the wavelength conversion member is low. Furthermore, in the light emitting device described in Patent Document 3 described above (see FIG. 7C), the sealing agent for sealing the phosphor of the wavelength conversion member is made of an inorganic material such as an epoxy resin, a silicone resin, and glass. Although illustrated, nothing is mentioned about the refractive index difference between the light guide unit 5 and the wavelength conversion unit 6.

  On the other hand, in the light emitting device 10 of the present embodiment, the wavelength conversion member 6 and the base material of the light guide 5 and the phosphor sealing material of the wavelength conversion member 6 are made of the same quartz (silicon oxide). Since the refractive index difference of the light guide unit 5 is reduced, it is possible to suppress a decrease in irradiation efficiency due to the significant difference in the refractive index. Further, in the light emitting device 10 of the present embodiment, the light guide part end surface SUF3 of the tip part 5a is brought into contact with the light emitting part surface SUF2 of the wavelength conversion member 6, or the tip part 5a is contacted with the light emitting part surface of the wavelength conversion member 6. It is inserted into the wavelength conversion member 6 from the SUF 2. For this reason, the loss of light at the interface between the wavelength conversion member 6 and the tip 5a can be reduced.

  Next, in the semiconductor light emitting device described in Patent Document 2 described above (see FIG. 7B), since the distance between the light incident portion of the inclined portion of the opening and the LD element is large, the light incident portion is There is a problem in that the probability that the excitation light and fluorescence that have returned to the LD element side will return to the wavelength conversion unit side again decreases. However, in the light emitting device 10 of the present embodiment, as described above, the wavelength conversion member 6 and the tip portion 5a are brought close to each other, and the tip portion 5a has a reflector structure. Light (fluorescence and excitation light) can be reflected and emitted forward in the optical axis direction. Further, Patent Document 3 describes that the area of the end surface of the light guide tip member is increased in order to increase the contact area with the wavelength conversion member, but the light guide emission end portion has a reflector structure. Therefore, the above-described effect of reflecting the return light of the light emitting device 10 of this embodiment cannot be obtained. Moreover, in the light-emitting device described in the same document, as in the light-emitting device 10 of the present embodiment, nothing is described about the viewpoint of integrating the wavelength conversion member with the reflector. For this reason, in the light-emitting device described in the document, the light extraction efficiency from the wavelength conversion member may be lower than that of the light-emitting device 10 of the present embodiment.

[Embodiment 2: Light-emitting device 20]
Next, based on FIG. 3, the structure of the light-emitting device (illuminating device) 20 which concerns on Embodiment 2 of this invention is demonstrated. FIG. 3 is a cross-sectional view showing the structure of the light emitting device 20. In the light emitting device 20 of the present embodiment, the light emitting side end surface (light guide unit end surface SUF3) of the tip 5a has a convex curved surface (convex surface) that protrudes near the center to form a convex 5b. Thus, it is different from the light emitting device 10 of Embodiment 1 described above. In addition, since the other structure of the light-emitting device 20 is the same as that of the light-emitting device 10, description is abbreviate | omitted here.

(Tip 5a)
In this embodiment, the front-end | tip part 5a is inserted toward the inside from the light emission part surface SUF2 side of the wavelength conversion member 6. FIG. Thereby, the loss of light at the interface between the wavelength conversion member 6 and the tip 5a is reduced. Moreover, in this embodiment, the light guide part end surface SUF3 of the front-end | tip part 5a makes the convex curved surface (convex surface) which the center vicinity protrudes, and forms the convex part 5b. Thereby, the contact area of the front-end | tip part 5a and the wavelength conversion member 6 is increased rather than the light-emitting device 10. FIG. Therefore, the density of the excitation light irradiated to the wavelength conversion member 6 is reduced, the heat dissipation of the wavelength conversion member is slightly improved, and the decrease in the irradiation efficiency of the excitation light on the wavelength conversion member 6 can be further suppressed. In addition, in this embodiment, although the shape of the convex part 5b is made into the convex curved surface shape, it is not limited to this. For example, the shape of the convex portion 5b may be a truncated cone shape, a truncated pyramid shape, a conical shape, a truncated pyramid shape, or the like.

<Effect of the light emitting device 20>
Here, in order to verify the effect of the light-emitting device 20 of the present embodiment, each of the light-emitting devices 10 and 20 of the first and second embodiments is prototyped, and the effect exhibited by the light-emitting device 10, the effect exhibited by the light-emitting device 20, The comparison results will be described below.

  Table 2 below shows the result of comparing the maximum luminous flux of the illumination light emitted from the light emitting device 20 of the second embodiment with the maximum luminous flux of the illumination light emitted from the light emitting device of the first embodiment as a reference. The light output of the LD, which is an excitation light source, was the same output. In the second embodiment, the maximum luminous flux is improved 1.05 times compared to the first embodiment. From this comparison result, it can be seen that the maximum luminous flux of the illumination light can be improved by about 5% as compared with the light emitting device 10 only by making the light guide part end surface SUF3 of the tip part 5a convex.

[Embodiment 3: Light-emitting device 30]
Next, based on (a) of FIG. 4, the structure of the light-emitting device (illuminating device) 30 which concerns on Embodiment 3 of this invention is demonstrated. FIG. 4A is a cross-sectional view illustrating the structure of the light emitting device 30. The light emitting device 30 according to the present embodiment is the light emitting device according to the first embodiment described above in that the heat conductive member 8 having translucency is provided on the end surface (light guide unit end surface SUF3) on the distal end portion 5a side. 10 and different.

  Furthermore, the excitation light source 1 used in the third embodiment includes five excitation light sources in order to increase the light output of the LD, and includes the light emitting device 30 or the light emitting device 10 and the bundle fiber 2 according to FIG. It is different from the light emitting device 10 of the first embodiment described above in that it is optically connected. In addition, since the other structure of the light-emitting device 30 is the same as that of the light-emitting device 10, description is abbreviate | omitted here.

(Thermal conductive member 8)
As shown in FIG. 4A, the heat conductive member 8 of the present embodiment is disposed between the light guide unit end surface SUF3 and the light emitting unit surface SUF2, and is sandwiched between these surfaces. Yes. The thermally conductive member 8 is a member having a high thermal conductivity. In this embodiment, a sapphire (Al ₂ O ₃ ; thermal conductivity 42 W / m · K) plate is used. However, the material of the heat conductive member 8 is not limited to this, and may be magnesia (MgO) or the like. By using the above materials, a thermal conductivity of 20 W / m · K or more can be realized.

  The thermal conductivity of the thermal conductive member 8 is higher than the thermal conductivity of 1.4 to 1.5 W / m · K of the sealing material of the wavelength conversion member 6 and the quartz glass that is the base material of the light guide unit 5. It is preferable. Thereby, the heat dissipation of the wavelength conversion member 6 can be improved. As a result, even if the optical output of the LD is increased, the wavelength conversion member 6 does not deteriorate.

  Moreover, the heat conductive member 8 is comprised with the material which has translucency, permeate | transmits the excitation light radiate | emitted from the front-end | tip part 5a, and is made to irradiate the wavelength conversion member 6. FIG. In order to suppress a decrease in the irradiation efficiency of the excitation light with respect to the wavelength conversion member 6, it is preferable that the refractive index differences of the heat conductive member 8, the wavelength conversion member 6, and the light guide unit 5 are small. In this embodiment, the heat conductive member 8 is a sapphire plate, and its refractive index is 1.75. Respective refractive indexes of the wavelength conversion member 6 and the light guide portion 5 are about 1.45 to 1.48, assuming that they are substantially equal to the base material. The refractive index of the sapphire plate (1.75) is the refractive index of each of the wavelength conversion member 6 and the light guide 5, and the refractive index of quartz glass (1.45-1.48) and the optical fiber 2 (core; 1.463 to 1.467, cladding; 1.45 to 1.46), which is about 0.3 higher than the refractive index. However, as compared with the case where air (refractive index = 1.0) is interposed between the wavelength conversion member and the LD element as in the light emitting device of Comparative Example 1 shown in FIG. Less than half, the impact is reduced.

  Further, according to the heat conductive member 8 having high heat conductivity, the tip 5a and the wavelength conversion member 6 can be thermally connected, and the heat generated in the wavelength conversion member 6 can be released, so that the wavelength conversion member can be released. The heat dissipation of 6 can be improved. For this reason, deterioration of the wavelength conversion member 6 can be suppressed even if the optical output of the excitation light is increased. The thickness of the heat conductive member 8 (approximately equal to the distance between the light emitting unit surface SUF2 and the light guide unit end surface SUF3) is more preferably 0.2 mm or more and 1.5 mm or less. If it is 0.2 mm or more, the heat radiation of the wavelength conversion member 6 can be sufficiently performed, and deterioration of the wavelength conversion member 6 can be prevented. On the other hand, when the heat conductive member 8 exceeds 1.5 mm, the rate at which the excitation light irradiated toward the heat conductive member 8 is absorbed by the heat conductive member 8 increases, and the utilization efficiency of the excitation light is increased. Is significantly reduced. In addition, by bonding the heat conductive member 8 to the wavelength conversion member 6 with an appropriate thickness as described above, an extremely strong laser beam that particularly generates heat at the wavelength conversion member 6 greatly exceeds 1 W (Watt). Even if it irradiates, the heat_generation | fever is rapidly and efficiently thermally radiated and it can prevent that the heat conductive member 8 and the wavelength conversion member 6 are damaged (deteriorated).

<Effect of light emitting device 30>
Here, in order to verify the effect of the light-emitting device 30 of the present embodiment, each of the light-emitting devices 10 and 30 of the first and third embodiments is prototyped, and the effect exhibited by the light-emitting device 10, the effect exhibited by the light-emitting device 30, The comparison results will be described below. FIG. 4B is a graph showing the relationship between the light output (W) of the excitation light source (LD) and the total luminous flux ratio of the light output from the light emitting devices 10 and 30 with respect to the light emitting devices 10 and 30. Yes (the total luminous flux of the light emitting device 10 when the light output of the LD is 3 W is 1.0). As shown in the figure, the light emitting device 30 of the present embodiment has a degree of linearity in the graph showing the relationship between the light output of the LD and the total luminous flux even if the light output of the LD increases. Is small. On the other hand, in the light emitting device 10, the linearity of the graph is significantly broken from the vicinity of the light output of the LD exceeding 3W. As described above, according to the light emitting device 30 of the present embodiment, compared with the light emitting device 10 of the first embodiment, even if the light output of the LD is increased, it is possible to emit illumination light with a high luminous flux corresponding thereto. I understand. For example, when the light output of the LD is 5 W, the total luminous flux of the light emitting device 30 is remarkably high at about 1.3 times the total luminous flux of the light emitting device 10.

[Embodiment 4: Light-emitting device 40]
Next, based on (a) of FIG. 5, the structure of the light-emitting device (illuminating device) 40 which concerns on Embodiment 4 of this invention is demonstrated. FIG. 5A is a cross-sectional view showing the structure of the light emitting device 40. In the light emitting device 40 of the present embodiment, the concentration of the phosphor contained in the wavelength conversion member 6a is higher than the concentration of the phosphor contained in the wavelength conversion member 6 of the light emitting device 30, and the illumination light of the wavelength conversion member 6a. The thickness d2 with respect to the traveling direction is different from the light emitting device 30 of Embodiment 3 described above in that the wavelength conversion member 6 of the light emitting device 30 is thinner than the thickness d1 with respect to the traveling direction of the illumination light. The excitation light source 1 uses five LDs as in the third embodiment. Since the other configuration of the light emitting device 40 is the same as that of the light emitting device 30 (or the light emitting device 10) in the third embodiment, the description thereof is omitted here.

(Wavelength conversion member 6a)
In the light emitting device 40 of this embodiment, the thickness d2 of the wavelength conversion member 6 is about 0.02 to 0.2 mm, which is thinner than the thickness d1 of the wavelength conversion member 6. The mixing amount of the phosphor with respect to the sealing agent (the base material of the wavelength conversion member 6) was adjusted so that the color temperature as the light emitting device was about 3000K. The amount of phosphor mixed per unit volume of the wavelength conversion member increases as the wavelength conversion member is thinner.

  The thermal conductivity (= about 20 W / m · K) of the oxynitride phosphor is higher than that of quartz glass (thermal conductivity = about 1.4 W / m · K) which is a sealing agent for sealing the phosphor. Since the phosphor concentration is high and the wavelength conversion member is thin, the thermal conductivity to the heat conductive member 8 is increased, the heat generation from the wavelength conversion member can be suppressed, and the excitation light with higher output can be suppressed. Irradiation is possible.

<Effect of light emitting device 40>
Here, in order to verify the effect of the light-emitting device 40 of the present embodiment, each of the light-emitting devices 10, 30, and 40 of Embodiments 1, 3, and 4 was prototyped and the effects exhibited by each light-emitting device were compared. The comparison result will be described. FIG. 5B shows the relationship between the light output (W) of the excitation light source (LD) and the total luminous flux ratio of the light output from the light emitting devices 10, 30, 40 with respect to the light emitting devices 10, 30, 40. (The total luminous flux of the light emitting device 10 when the light output of the LD is 3 W is 1.0). As shown in the figure, in the light emitting device 40 of this embodiment, even when the light output of the LD increases, the linearity of the graph showing the relationship between the light output of the LD and the total luminous flux is hardly broken. On the other hand, in the light emitting device 10, the linearity of the graph is significantly broken from the light output of the LD from around 3 W. On the other hand, in the light emitting device 30, the linearity of the graph is more gradual than that of the light emitting device 10, but the linearity of the graph is slightly broken from around 4 W. As described above, according to the light emitting device 40 of the present embodiment, compared with the light emitting devices 10 and 30 of the first and third embodiments, even if the light output of the LD is increased, the illumination light with a high luminous flux corresponding thereto is emitted. You can see that For example, when the light output of the LD is 5 W, the total luminous flux of the light emitting device 40 is about 1.6 times that of the light emitting device 10 and about 1.25 times that of the light emitting device 30. .

[Embodiment 5: Lighting device 50a]
Next, based on (a) of FIG. 6, the structure of the light-emitting device (illuminating device) 50a which concerns on Embodiment 5 of this invention is demonstrated.

  The illuminating device 50a of this embodiment is configured to include any one of the above-described light emitting devices of Embodiments 10 to 40 and the heat sink 9, and is applied to an illuminating device such as a spotlight. In the illuminating device 50a of this embodiment, the distance between the wavelength conversion members 6 and 6a and the excitation light source 1 (semiconductor laser) is separated by the optical fiber 2. As a result, since the heat generation in the wavelength conversion members 6 and 6a and the excitation light source 1 can be separated, the wavelength conversion members 6 and 6a need not be affected by the heat generation in the excitation light source 1. Thereby, the magnitude | size of the whole light-emitting device part (light-emitting devices 10-40) including the heat sink 9 (lamp) except the excitation light source 1 can be made small. Moreover, in the illuminating device 50a of this embodiment, the circumference | surroundings of the cross-sectional direction of the light guide part 5 are further thermally connected to the heat sink 9, and heat dissipation is improved.

[Modification: Lighting device 50b]
A configuration in which a plurality of excitation light sources 1 are provided and optically connected to any one of the light emitting devices 10 to 40 by a bundle fiber 2a as in the illumination device 50b of the modified example illustrated in FIG. 6B may be employed. . In this modification, the number of excitation light sources 1 is three, but the number of excitation light sources 1 may be two or more. Thereby, the light output of the illumination light of the illuminating device 50b can be easily increased without changing the size of the entire light emitting device portion (light emitting devices 10 to 40) including the heat sink 9 (lamp).

[Summary]
The light emitting device (10 to 40) according to the first aspect of the present invention includes a light propagation portion formed of a material having a light-transmitting material as a base material, and emits light propagated through the light propagation portion. A light guide part (5) and a wavelength conversion member (6) for converting the wavelength of light emitted from the light guide part, and an emission end part (end part on the light emission side of the light propagation part) The tip 5a) has a structure that monotonously increases as the diameter of the cross section perpendicular to the light traveling direction approaches the wavelength conversion member side.

  According to the said structure, the light guide part has the light propagation part formed with the material which uses as a base material the material which has translucency. In addition, an emission end portion that is an end portion on the light emission side of the light propagation portion has a structure that monotonously increases as the diameter of the cross section perpendicular to the light traveling direction approaches the wavelength conversion member side. For this reason, the spot diameter of the light guided to the exit end can be enlarged. As a result, even if the emission end portion is brought close to the wavelength conversion member, it is possible to suppress the concentration of the excitation light from being partially concentrated in a narrow range of a part of the wavelength conversion member, thereby suppressing deterioration of the wavelength conversion member. Can do. As described above, it is possible to improve the effect of suppressing the deterioration of the wavelength conversion member when the exit end of the light guide unit is brought close to the wavelength conversion member.

  In the light emitting device according to aspect 2 of the present invention, in the above aspect 1, the end face of the emission end portion may be in contact with the wavelength conversion member.

  According to the said structure, the loss of the light in the interface of a wavelength conversion member and an output edge part can be reduced, and the fall of the irradiation efficiency of the excitation light with respect to a wavelength conversion member can be suppressed.

  The light-emitting device according to aspect 3 of the present invention is the light-emitting device according to aspect 1, in which the emission end is inserted from the side of the light irradiation side irradiated with the light of the wavelength conversion member toward the inside of the wavelength conversion member. May be.

  According to the said structure, the loss of the light in the interface of a wavelength conversion member and an output edge part can be reduced, and the fall of the irradiation efficiency of the excitation light with respect to a wavelength conversion member can be suppressed.

  In the light emitting device according to aspect 4 of the present invention, in any one of the above aspects 1 to 3, the base material of the wavelength conversion member and the base material of the light guide section may be the same material.

  According to the said structure, the loss of the light in the interface of a wavelength conversion member and an output edge part can be reduced, and the fall of the irradiation efficiency of the excitation light with respect to a wavelength conversion member can be suppressed.

  The light-emitting device which concerns on aspect 5 of this invention in any one of the said aspects 1-4 may have the coating | coated part which has light reflectivity and coat | covers the said light guide part.

  According to the said structure, the interface of a coating | coated part and a light guide part plays the role of a mirror, and as above-mentioned, the exit end part has the diameter of the cross section perpendicular | vertical to the advancing direction of light, and approaches the wavelength conversion member side. Therefore, the return light (excitation light or wavelength converted light) from the wavelength conversion member can easily enter the wavelength conversion member again. For this reason, the light emission efficiency as a light-emitting device and the light extraction efficiency can be improved.

  The light emitting device according to aspect 6 of the present invention is the light emitting device according to any one of aspects 1 to 5, wherein the end surface of the light guide portion on the emission end portion side is configured by a convex surface protruding toward the wavelength conversion member. May be.

  According to the said structure, a contact area with a wavelength conversion member can be increased rather than when the end surface at the side of the output end part of a light guide part is a plane. For this reason, the density of the excitation light irradiated to the wavelength conversion member is reduced, the heat dissipation of the wavelength conversion member is improved, and the irradiation efficiency of the excitation light to the wavelength conversion member can be improved.

  In the light emitting device according to aspect 7 of the present invention, in the aspect 1, a heat conductive member having translucency may be provided on an end surface of the light guide portion on the emission end portion side.

  According to the above configuration, the wavelength conversion member can be thermally connected to the end face of the light guide portion on the emission end side, and the heat generated in the wavelength conversion member can be released, so the heat dissipation of the wavelength conversion member is improved. be able to. For this reason, deterioration of the wavelength conversion member can be suppressed even if the optical output of the excitation light is increased.

  An illuminating device according to aspect 8 of the present invention includes the light-emitting device according to any one of aspects 1 to 7, and a reflecting mirror having a light reflecting concave surface that reflects light emitted from the wavelength conversion member. The surface on the light irradiation side where the light of the wavelength conversion member is irradiated may be bonded to the bottom near the focal point of the light reflecting concave surface.

  According to the above configuration, since the wavelength conversion member and the bottom near the focal point of the light reflecting concave surface are integrated, the light extraction efficiency from the wavelength conversion member can be increased.

[Additional Notes]
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment.

  The present invention can be applied to light-emitting devices and lighting devices, particularly lighting devices such as spotlights.

DESCRIPTION OF SYMBOLS 1 Excitation light source 4 Covering part 5 Light guide part 5a Tip part (output end part, light propagation part)
5b Core (light propagation part)
6, 6a Wavelength conversion member 7 Reflector (reflector)
8 Thermally conductive members 10 to 40 Light emitting device (lighting device)
50a Illuminating device 50b Illuminating device SUF1 Cover surface SUF2 Light emitting surface SUF3 Light guide end surface (convex surface)

Claims (8)

A light propagation part formed of a material having a light-transmitting material as a base material, and a light guide part that emits light propagated through the light propagation part;
A wavelength conversion member that converts the wavelength of light emitted from the light guide unit,
The exit end, which is the end on the light exit side of the light propagation part, has a structure in which the diameter of the cross section perpendicular to the light traveling direction increases monotonously as it approaches the wavelength conversion member side. A light emitting device characterized.   The light emitting device according to claim 1, wherein an end face of the emission end portion is in contact with the wavelength conversion member.   2. The light emitting device according to claim 1, wherein the emission end portion is inserted toward the inside of the wavelength conversion member from a light irradiation side surface irradiated with light of the wavelength conversion member. .   The light emitting device according to any one of claims 1 to 3, wherein the base material of the wavelength conversion member and the base material of the light guide section are the same material.   5. The light emitting device according to claim 1, further comprising a covering portion that has light reflectivity and covers the light guide portion.   6. The light emitting device according to claim 1, wherein an end surface of the light guide portion on the emission end portion side is formed by a convex surface protruding toward the wavelength conversion member. apparatus.   The light emitting device according to claim 1, wherein a heat conductive member having translucency is provided on an end face of the light guide portion on the emission end portion side. A light emitting device according to any one of claims 1 to 7,
A reflecting mirror having a light reflecting concave surface that reflects the light emitted from the wavelength conversion member, and
The illumination device, wherein a surface of the wavelength conversion member on which light is irradiated is joined to a bottom near the focal point of the light reflecting concave surface.

Images