Light source device
The light source device efficiently dissipates heat using transparent and metal members with higher thermal conductivity than the phosphor, addressing cooling performance and complexity issues, ensuring stable light output and simplicity.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- OXIDE
- Filing Date
- 2024-12-23
- Publication Date
- 2026-07-03
Smart Images
Figure 2026111247000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a light source device capable of exciting a phosphor element with excitation light and emitting light emitted from the phosphor element.
Background Art
[0002] Conventional light source devices are disclosed in, for example, Patent Documents 1 to 5.
[0003] In Patent Document 1, while rotating a ring-shaped fluorescent wheel in which phosphor particles are solidified with resin at high speed, by irradiating the fluorescent wheel with laser light as excitation light, while suppressing the temperature rise of the fluorescent wheel, A light source device for obtaining fluorescent light from a fluorescent wheel is disclosed. However, in the light source device described in Patent Document 1, it causes the device to be enlarged and complicated, and such a large and complicated light source device causes great restrictions when applied to a system.
[0004] In Patent Document 2, a light source device for obtaining fluorescent light from a wavelength conversion member by irradiating the wavelength conversion member in which phosphor particles are solidified with an inorganic binder with LED light as excitation light is disclosed. In the light source device described in Patent Document 2, by using an inorganic binder, the heat resistance of the wavelength conversion member itself is improved. However, when heat accumulation progresses in the wavelength conversion member due to heat generation of the phosphor particles, the light emission performance of the phosphor particles disappears, and it is difficult to use in a high-energy environment.
[0005] In Patent Document 3, it is disclosed that by making the ratio of the thickness of the phosphor element to the average particle diameter of the phosphor particles less than 30 and further using sapphire having high thermal conductivity as a base material, the temperature rise of the phosphor layer can be suppressed. Further, in Patent Document 4, it is disclosed that a cooling mechanism by a heat sink directly contacting the base material is provided using a glass substrate as the base material. Further, in Patent Document 5, a method of immersing the phosphor in a cooling medium is disclosed.
Prior Art Documents
Patent Documents
[0006] [Patent Document 1] Japanese Patent Publication No. 2015-94777 [Patent Document 2] Japanese Patent Publication No. 2015-90887 [Patent Document 3] International release WO2017 / 126440 [Patent Document 4] Japanese Patent Publication No. 2012-169049 [Patent Document 5] Japanese Patent Publication No. 2015-184434 [Overview of the project] [Problems that the invention aims to solve]
[0007] However, the methods described in Patent Documents 3 and 4 have the problem of not being able to obtain sufficient cooling performance. Furthermore, the method described in Patent Document 5 requires a mechanism to prevent leakage of the cooling medium, which can be a major constraint when applying it to a system.Therefore, it is desirable to provide a light source device that can obtain sufficient cooling performance with a simple configuration. [Means for solving the problem]
[0008] A light source device according to one embodiment of the present invention comprises a phosphor element having a light incident surface and a light emission surface facing each other, and a light source unit capable of irradiating the light incident surface with incident excitation light, which is excitation light capable of exciting the phosphor element. This light source device further comprises a first transparent member and a second transparent member arranged facing each other with the phosphor element in between, and a first metal member and a second metal member arranged facing each other with the phosphor element, the first transparent member and the second transparent member in between. The first transparent member is in contact with the light incident surface. The second transparent member is in contact with the light emission surface. The first metal member is in contact with the first transparent member. The second metal member is in contact with the second transparent member. The first transparent member, the second transparent member, the first metal member and the second metal member have a thermal conductivity higher than that of the phosphor element. [Effects of the Invention]
[0009] According to one embodiment of the present invention, a first transparent member in contact with the light incident surface, a second transparent member in contact with the light emission surface, a first metal member in contact with the first transparent substrate, and a second metal member in contact with the second transparent substrate are made of materials having a thermal conductivity higher than that of the phosphor element. Therefore, compared to the case where these members are not provided, the heat generated by the phosphor element can be efficiently dissipated to the outside through these members. Here, these members have a simpler configuration compared to mechanisms for rotating the phosphor element at high speed or mechanisms for immersing the phosphor element in a cooling medium. Furthermore, these members function as heat sinks for the phosphor element. Therefore, sufficient cooling performance can be obtained with a simple configuration. [Brief explanation of the drawing]
[0010] [Figure 1] Figure 1 is a diagram showing a schematic configuration example of a light source device according to one embodiment of the present invention. [Figure 2] Figure 2 is a magnified view of a part of the light source device shown in Figure 1. [Figure 3] Figure 3 shows an example of the relationship between numerical aperture (NA) and aperture diameter in the light source device shown in Figure 1. [Figure 4] Figure 4 is a diagram showing a schematic configuration example of a light source device according to comparative example a. [Figure 5] Figure 5 is a diagram showing an example of the relationship between the power of the incident excitation light and the amount of combined light for the light source device according to the embodiment and the light source device according to the comparative example. [Figure 6] Figure 6 shows an example of the relationship between the power of the incident excitation light and the spectral output ratio of the light source device according to the embodiment and the light source device according to the comparative example. [Figure 7] Figure 7 shows a modified example of the schematic configuration of the light source device shown in Figure 1. [Modes for carrying out the invention]
[0011] Hereinafter, embodiments for implementing the present invention will be described in detail with reference to the drawings. The following description is a specific example of the present invention, and the present invention is not limited to the following aspects. Also, the present invention is not limited to the arrangement, dimensions, dimensional ratios, etc. of each component shown in each figure.
[0012] <1. Background> Conventional light source devices are disclosed in, for example, Patent Documents 1 to 5.
[0013] Patent Document 1 discloses a light source device that irradiates a ring-shaped fluorescent wheel in which phosphor particles are solidified with resin with laser light as excitation light while rotating the fluorescent wheel at high speed, thereby suppressing the temperature rise of the fluorescent wheel and obtaining fluorescent light from the fluorescent wheel. However, in the light source device described in Patent Document 1, the device becomes large and complex, and such a large and complex light source device causes great restrictions when applied to a system. >
[0014] Patent Document 2 discloses a light source device that irradiates a wavelength conversion member in which phosphor particles are solidified with an inorganic binder with LED light as excitation light to obtain fluorescent light from the wavelength conversion member. In the light source device described in Patent Document 2, the heat resistance of the wavelength conversion member itself is improved by using an inorganic binder. However, if heat accumulation progresses in the wavelength conversion member due to heat generation of the phosphor particles, the light emission performance of the phosphor particles disappears, and it is difficult to use in a high-energy environment.
[0015] Patent Document 3 discloses that by setting the ratio of the thickness of the phosphor element to the average particle diameter of the phosphor particles to less than 30 and further using sapphire having high thermal conductivity as a base material, the temperature rise of the phosphor layer can be suppressed. Patent Document 4 discloses providing a cooling mechanism by a heat sink directly contacting the base material using a glass substrate as the base material. Patent Document 5 discloses a method of immersing the phosphor in a cooling medium.
[0016] However, the methods described in Patent Documents 3 and 4 have a problem that sufficient cooling performance cannot be obtained. Also, the method described in Patent Document 5 requires a mechanism for preventing leakage of the cooling medium, which can be a major limitation when applied to a system. Therefore, as a result of intensive studies, the inventor of the present application conceived an invention that can obtain sufficient cooling performance with a simple configuration.
[0017] Hereinafter, modes for carrying out the present invention will be described in detail with reference to the drawings. The following description is a specific example of the present invention, and the present invention is not limited to the following aspects. Also, the present invention is not limited to the arrangement, dimensions, dimensional ratios, etc. of each component shown in each figure.
[0018] <2. Embodiment> [Configuration] The configuration of a light source device 100 according to an embodiment of the present invention will be described. FIG. 1 shows a schematic configuration example of the light source device 100. The light source device 100 includes, for example, as shown in FIG. 1, a light source unit 110, a phosphor element 120, a housing unit 130, and lenses 140 and 150. The light source unit 110 corresponds to a specific example of the "light source unit" according to an embodiment of the present disclosure. The phosphor element 120 corresponds to a specific example of the "phosphor element" according to an embodiment of the present disclosure. The lens 140 corresponds to a specific example of the "condensing lens" according to an embodiment of the present disclosure. The lens 150 corresponds to a specific example of the "collimating lens" according to an embodiment of the present disclosure.
[0019] The light source unit 110 is capable of emitting excitation light (incident excitation light La) that can excite the phosphor contained in the phosphor element 120. The light source unit 110 is capable of incident the incident excitation light La on the light incident surface Sa of the phosphor element 120 at an angle parallel to the normal to the light incident surface Sa of the phosphor element 120. In other words, the optical axis AX of the incident excitation light La is orthogonal to the light incident surface Sa. The light source unit 110 is composed of, for example, a semiconductor laser that emits the incident excitation light La. The wavelength of the incident excitation light La is a wavelength within the visible wavelength range, for example, a wavelength within the blue wavelength range. The wavelength of the incident excitation light La is not limited to a wavelength within the blue wavelength range, but is a wavelength that can excite the phosphor contained in the phosphor element 120.
[0020] The phosphor element 120 is composed of a phosphor. Examples of phosphor material systems include single-crystal materials, eutectic materials, or inorganic compound materials with a garnet structure containing aluminum and oxygen, to which one or more rare earth elements are added. The phosphor element 120 may also be a sintered body formed by solidifying powdered phosphor through sintering. When the phosphor contained in the phosphor element 120 is irradiated with incident excitation light La, it is excited by the irradiated incident excitation light La and is capable of emitting fluorescent light Lc. When the phosphor contained in the phosphor element 120 is composed of the above-mentioned materials, the wavelength of the fluorescent light Lc is in a wavelength range longer than the wavelength of the excitation light.
[0021] The phosphor element 120 is a flat plate-shaped element having a light incident surface Sa and a light emission surface Sb that face each other. Both the light incident surface Sa and the light emission surface Sb are, for example, mirror surfaces. In the phosphor element 120, when incident excitation light La is incident on the light incident surface Sa, the phosphor contained in the phosphor element 120 is excited by the incident excitation light La, and fluorescent light Lc is emitted from the phosphor. The fluorescent light Lc is emitted from the light emission surface Sb. In the phosphor element 120, when incident excitation light La is incident on the light incident surface Sa, not only is fluorescent light Lc emitted from the phosphor, but heat is also emitted from the phosphor. The heat emitted from the phosphor is dissipated to the outside through the housing 130. The size of the phosphor element 120 is larger than the diameter of the irradiation spot of the incident excitation light La that irradiates the phosphor element 120. The phosphor element 120 has a thickness that allows it to produce the necessary color as a composite light Ld, which is the light transmitted through the phosphor element 120 (transmitted excitation light Lb) and the fluorescent light Lc emitted from the phosphor element 120, from the incident excitation light La.
[0022] The housing section 130 supports the phosphor element 120 and is capable of housing the phosphor element 120. The housing section 130 has transparent members 131, 132 and metal members 133, 134, 135. The phosphor element 120 is arranged in the space surrounded by the transparent members 131, 132 and the metal members 133, 134, 135. Transparent member 131 corresponds to a specific example of the "first transparent member" according to one embodiment of the present disclosure. Transparent member 132 corresponds to a specific example of the "second transparent member" according to one embodiment of the present disclosure. Metal member 134 corresponds to a specific example of the "first metal member" according to one embodiment of the present disclosure. Metal member 135 corresponds to a specific example of the "second metal member" according to one embodiment of the present disclosure.
[0023] The transparent members 131 and 132 are positioned facing each other with the phosphor element 120 in between. In the transparent members 131 and 132, both the light incident surface and the light emission surface are, for example, mirror surfaces. The metal members 134 and 135 are positioned facing each other with the phosphor element 120 and the transparent members 131 and 132 in between. The metal member 133 supports the phosphor element 120, the transparent members 131 and 132, and the metal members 134 and 135. The transparent member 131 is in contact with the light incident surface Sa. The transparent member 132 is in contact with the light emission surface Sb. The metal member 134 is in contact with the surface of the transparent member 131 opposite to the phosphor element 120 side. The metal member 135 is in contact with the surface of the transparent member 132 opposite to the phosphor element 120 side. The transparent member 131 is bonded to the metal member 134 by contact or bonding. The transparent member 132 is bonded to the metal member 135 by contact or bonding. The metal member 133 is bonded to the edges of the metal members 134 and 135.
[0024] The transparent members 131, 132 and the metal members 133, 134, 135 have a higher thermal conductivity than the phosphor contained in the phosphor element 120. The transparent members 131, 132 are, for example, sapphire plates (thermal conductivity approximately 25 W / cmK) or diamond plates (thermal conductivity approximately 33.2 W / cmK). The metal members 133, 134, 135 are, for example, made of an aluminum alloy or a copper alloy. Therefore, the housing 130 functions as a heat sink capable of absorbing the heat emitted from the phosphor element 120 and dissipating it to the outside.
[0025] Lens 140 is capable of irradiating the incident excitation light La onto the light incident surface Sa of the phosphor element 120. Lens 140 is positioned opposite the aperture Ha, which will be described later. When the incident excitation light La incident on lens 140 is divergent light, lens 140 is composed of, for example, a lens α that aligns the incident excitation light La and a lens β that focuses the light that has been aligned by lens α. Lens β is positioned such that its focal length is equal to, or approximately equal to, the distance between lens β and the center of the phosphor element 120 in the thickness direction.
[0026] Lens 150 is capable of combining transmitted excitation light Lb and fluorescence light Lc, and outputting the resulting combined light Ld to the outside as output light. Lens 150 is capable of collimating transmitted excitation light Lb and fluorescence light Lc. The combined light Ld is made into parallel light by lens 150. Lens 150 is positioned opposite the aperture Hb described later. Lens 150 is positioned on the path of transmitted excitation light Lb. Lens 150 is positioned so that its optical axis coincides with the optical axis of lens 140. Lens 150 is positioned so that its focal length is equal to, or approximately equal to, the distance between lens 150 and the center of the phosphor element 120 in the thickness direction. Lenses 140 and 150 have equal focal lengths and numerical apertures (NA).
[0027] Figure 3 shows an example of the relationship between the numerical aperture (NA) and the aperture diameter D in the light source device 100. The metal member 134 is provided with an aperture Ha at a location corresponding to the optical path of the incident excitation light La, as shown in Figures 1 and 2. Furthermore, the metal member 135 is provided with an aperture Hb at a location corresponding to the optical path of the transmitted excitation light Lb, as shown in Figures 1 and 2. Aperture Ha corresponds to a specific example of the "first aperture" according to one embodiment of this disclosure. Aperture Hb corresponds to a specific example of the "second aperture" according to one embodiment of this disclosure. The edges of apertures Ha and Hb are circular in shape. The aperture diameter D (diameter) of aperture Hb satisfies the following relationship. When NA = 0.45, the aperture diameter D must be greater than 1 mm. This ensures that the components of the transmitted excitation light Lb and fluorescence light Lc that can be incident on the lens 150 are not blocked by the metal member 135. D>2×f×tan(sin -1 (NA)) D: Aperture diameter of aperture Hb f: Focal length of lens 140, 150 NA: Numerical aperture of lens 140, 150
[0028] [effect] Next, the effects of the phosphor element 1 according to this embodiment will be explained in comparison with a comparative example.
[0029] Figure 4 shows a schematic configuration example of the light source device 200 according to comparative example a. The light source device 200 includes, for example, a light source unit 210, a phosphor element 220, a support unit 230, and lenses 240, 250, as shown in Figure 4.
[0030] The light source unit 210 is capable of emitting excitation light (incident excitation light L1) that can excite the phosphor contained in the phosphor element 220. The light source unit 210 is capable of irradiating the incident excitation light L1 to the light incident surface of the phosphor element 220 at an angle parallel to the normal to the light incident surface of the phosphor element 220. The light source unit 210 is composed of, for example, a semiconductor laser that emits the incident excitation light L1. The wavelength of the incident excitation light L1 is a wavelength within the visible wavelength range, for example, a wavelength within the blue wavelength range.
[0031] The phosphor element 220 is composed of a phosphor. Examples of phosphor material systems include single-crystal materials, eutectic materials, or inorganic compound materials with a garnet structure containing aluminum and oxygen, to which one or more rare earth elements are added. The phosphor element 220 may also be a sintered body obtained by solidifying powdered phosphor through sintering. When the phosphor contained in the phosphor element 220 is irradiated with incident excitation light L1, it is excited by the irradiated incident excitation light L1 and is able to emit fluorescent light L3. When the phosphor contained in the phosphor element 220 is composed of the above-mentioned materials, the wavelength of the fluorescent light L3 is in a wavelength range longer than the wavelength of the excitation light.
[0032] In the phosphor element 220, when incident excitation light L1 strikes the light incident surface, the phosphor contained in the phosphor element 220 is excited by the incident excitation light L1, and fluorescent light L3 is emitted from the phosphor. The fluorescent light L3 is emitted from the light emission surface. In the phosphor element 220, when incident excitation light L1 strikes the light incident surface, not only is fluorescent light L3 emitted from the phosphor, but heat is also emitted from the phosphor. The heat emitted from the phosphor is dissipated to the outside through the support part 230.
[0033] The light-emitting surface of the phosphor element 220 is rough. As a result, the light that propagates within the phosphor element 220 from the incident excitation light L1 is scattered by the rough light-emitting surface. Consequently, the light that passes through the phosphor element 220 from the incident excitation light L1 (transmitted excitation light L2) is scattered and emitted to the outside. A portion of the transmitted excitation light L2 and the fluorescence light L3 emitted from the phosphor element 220 are combined by the lens 250 and emitted to the outside as combined light L4.
[0034] The support portion 230 is capable of supporting the phosphor element 220. The support portion 230 has a transparent member 231 and a metal member 232. The phosphor element 220 is bonded to the transparent member 231. The transparent member 231 is bonded to the metal member 232. The metal member 232 is provided with an opening H1. The opening H1 is provided at a location corresponding to the optical path of the incident excitation light L1.
[0035] Lens 240 is capable of irradiating the light incident surface of the phosphor element 220 with incident excitation light L1. Lens 250 is capable of combining a portion of the transmitted excitation light L2 and the fluorescent light L3, and outputting the resulting combined light L4 to the outside as output light.
[0036] Figure 5 shows an example of the relationship between the power of the incident excitation light and the amount of combined light for the light source device 100 according to the embodiment and the light source devices according to comparative examples a and b. In the light source device 100 according to the embodiment, diamond plates were used as transparent members 131 and 132, and copper alloys were used as metal members 133, 134, and 135. The light source device according to comparative example b is equivalent to the light source device according to comparative example a, in which the support part 230 is omitted. In the light source device according to comparative example a, a diamond plate was used as the transparent member 231, and a copper alloy was used as the metal member 232.
[0037] In the light source device according to Comparative Example b, a decrease in output light intensity due to heat occurred at 500 mW. In the light source device according to Comparative Example a, a decrease in output light intensity due to heat occurred at 700 mW. In the light source device 100 according to the Example, no decrease in output light intensity was observed even at 1000 mW. From this, it can be seen that the light source device 100 according to the Example is able to efficiently dissipate the heat emitted from the phosphor element 120 by the containment section 130, and is capable of handling high-intensity incident excitation light La.
[0038] Figure 6 shows an example of the relationship between the incident excitation light power and the spectral output ratio for the light source device 100 according to the embodiment and the light source devices according to comparative examples a and b. The spectral output ratio is a value obtained by dividing the transmitted excitation light power by the fluorescence light power. When the incident excitation light power increases, heat is generated from the phosphor, and the temperature of the phosphor rises. This leads to a decrease in fluorescence light power and a decrease in the phosphor's absorption rate, causing the transmitted excitation light power to increase. As a result, the spectral output ratio changes with increasing incident excitation light power. This trend can also be seen in Figure 6.
[0039] In the light source device according to Comparative Example b, the change in spectral output ratio was 0.6 / W. In the light source device according to Comparative Example a, the change in spectral output ratio was 0.4 / W. In the light source device 100 according to the Example, the change in spectral output ratio was 0.1 / W, and there was almost no change in the spectral output ratio. A small change in spectral output ratio means that there is little color shift (chromaticity change) of the synthesized light. From this, it can be seen that in the light source device 100 according to the Example, the heat emitted from the phosphor element 120 is efficiently discharged by the containment section 130, and there is little change in the chromaticity of the output light.
[0040] From the above, in the light source device 100 according to this embodiment, the heat emitted from the phosphor element 120 can be efficiently dissipated by the housing section 130, making it possible to handle high-intensity incident excitation light La, and also reducing the change in chromaticity of the output light. Furthermore, in the light source device 100 according to this embodiment, the housing section 130, which functions as a heat sink, has a simpler configuration compared to mechanisms that rotate the phosphor element at high speed or mechanisms that immerse the phosphor element in a cooling medium. Therefore, sufficient cooling performance can be obtained with a simple configuration.
[0041] Furthermore, in this embodiment, the aperture diameter D of the aperture Hb of the metal member 135 satisfies the above-described relation. As a result, the components of the transmitted excitation light Lb and fluorescence light Lc that can enter the lens 150 are not blocked by the metal member 135. Consequently, a decrease in the power of the composite light Ld due to vignetting by the metal member 135 can be prevented. In addition, in this embodiment, both the light incident surface Sa and the light exit surface Sb are mirror surfaces, and furthermore, in the transparent members 131 and 132, both the light incident surface and the light exit surface are mirror surfaces, so that light scattering on these surfaces can be suppressed. Consequently, a decrease in the power of the composite light Ld due to vignetting by the metal member 135 can be prevented more effectively.
[0042] <3. Variant> In the above embodiment, the light source device 100 may further include, for example, an optical fiber 160 that optically couples the light source unit 110 and the lens 140, and an optical fiber 170 that optically couples with the lens 150, as shown in Figure 7. In this case, the light source device 100 can be used as a light source for various applications.
[0043] Figure 7 shows an example in which lens 140 is composed of lens 141 having the same function as lens α described above and lens 142 having the same function as lens β described above. Also, Figure 7 shows an example in which lens 150 is composed of lens 151 having the same function as lens α described above and lens 152 having the same function as lens β described above.
[0044] Furthermore, the light source device 100 can be applied to various fields such as laser displays, laser illumination, projection mapping, and medical applications. Examples of laser displays include laser projectors, laser TVs, and head-mounted displays. Examples of laser illumination include light sources for microscopes, vehicle headlamps, indoor indirect lighting, and light sources for plant factories. Examples of medical applications include light sources for endoscopes and laser scalpels. [Explanation of Symbols]
[0045] 100,200...Light source device, 110,210...Light source unit, 120,220...Phosphor element, 130...Housing unit, 131,132,231...Transparent member, 133,134,135,232...Metal member, 140,141,142,150,151,152...Lens, 160,170...Optical fiber, AX...Optical axis, D...Aperture diameter, d...Distance, f...Focal length, Ha,Hb,H1...Aperture, La,L1...Incident excitation light, Lb,L2...Transmitted excitation light, Lc,L3...Fluorescent light, Ld,L4...Synthesized light.
Claims
1. A phosphor element having a light-incident surface and a light-emitting surface facing each other, A light source unit capable of irradiating the light incident surface with incident excitation light, which is excitation light capable of exciting the phosphor element, A first transparent member and a second transparent member are arranged facing each other with the aforementioned phosphor element in between, The phosphor element, the first transparent member, and the second transparent member are arranged opposite each other with the first metal member and the second metal member in between. Equipped with, The first transparent member is in contact with the light incident surface, The second transparent member is in contact with the light-emitting surface, The first metal member is in contact with the first transparent substrate. The second metal member is in contact with the second transparent substrate. The first transparent member, the second transparent member, the first metal member, and the second metal member have a thermal conductivity higher than that of the phosphor element. Light source device.
2. The first transparent member and the second transparent member are sapphire plates or diamond plates. The light source device according to claim 1.
3. The first metal member is provided with a first aperture at a location corresponding to the optical path of the incident excitation light, The second metal member is provided with a second aperture at a location corresponding to the optical path of the transmitted excitation light that has passed through the phosphor element, among the incident excitation light. The light source device is A focusing lens is positioned opposite the first aperture and capable of focusing the incident excitation light onto the light incident surface. A collimating lens is positioned opposite the second aperture and capable of collimating the transmitted excitation light and the fluorescent light. It also has A light source device according to claim 1 or claim 2.
4. In the aforementioned focusing lens and collimating lens, the focal length and numerical aperture are equal to each other. The light source device according to claim 3.
5. The diameter of the second opening satisfies the following relationship. The light source device according to claim 4. 52×0×100 －１ (PO)) D: Diameter of the second opening f: Focal length of the condensing lens and the collimating lens NA: Numerical aperture of the condensing lens and the collimating lens.